The kernel’s command-line parameters — The Linux Kernel 5.18.5-gnu-1 documentation

# The kernel’s command-line parameters

The following is a consolidated list of the kernel parameters as implemented by the __setup(), early_param(), core_param() and module_param() macros and sorted into English Dictionary order (defined as ignoring all punctuation and sorting digits before letters in a case insensitive manner), and with descriptions where known.

The kernel parses parameters from the kernel command line up to “`--`“; if it doesn’t recognize a parameter and it doesn’t contain a ‘.’, the parameter gets passed to init: parameters with ‘=’ go into init’s environment, others are passed as command line arguments to init. Everything after “`--`” is passed as an argument to init.

Module parameters can be specified in two ways: via the kernel command line with a module name prefix, or via modprobe, e.g.:

    (kernel command line) usbcore.blinkenlights=1
    (modprobe command line) modprobe usbcore blinkenlights=1

Parameters for modules which are built into the kernel need to be specified on the kernel command line. modprobe looks through the kernel command line (/proc/cmdline) and collects module parameters when it loads a module, so the kernel command line can be used for loadable modules too.

Hyphens (dashes) and underscores are equivalent in parameter names, so:

    log_buf_len=1M print-fatal-signals=1

can also be entered as:

    log-buf-len=1M print_fatal_signals=1

Double-quotes can be used to protect spaces in values, e.g.:

    param="spaces in here"

## cpu lists:

Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, nohz_full, irqaffinity, rcu_nocbs. The format of this list is:

> <cpu number>,…,<cpu number>

or

> <cpu number>-<cpu number> (must be a positive range in ascending order)

or a mixture

<cpu number>,…,<cpu number>-<cpu number>

Note that for the special case of a range one can split the range into equal sized groups and for each group use some amount from the beginning of that group:

> <cpu number>-<cpu number>:<used size>/<group size>

For example one can add to the command line following parameter:

> isolcpus=1,2,10-20,100-2000:2/25

where the final item represents CPUs 100,101,125,126,150,151,…

The value “N” can be used to represent the numerically last CPU on the system, i.e “foo_cpus=16-N” would be equivalent to “16-31” on a 32 core system.

Keep in mind that “N” is dynamic, so if system changes cause the bitmap width to change, such as less cores in the CPU list, then N and any ranges using N will also change. Use the same on a small 4 core system, and “16-N” becomes “16-3” and now the same boot input will be flagged as invalid (start > end).

The special case-tolerant group name “all” has a meaning of selecting all CPUs, so that “nohz_full=all” is the equivalent of “nohz_full=0-N”.

The semantics of “N” and “all” is supported on a level of bitmaps and holds for all users of `bitmap_parse()`.

This document may not be entirely up to date and comprehensive. The command “modinfo -p ${modulename}” shows a current list of all parameters of a loadable module. Loadable modules, after being loaded into the running kernel, also reveal their parameters in /sys/module/${modulename}/parameters/. Some of these parameters may be changed at runtime by the command `echo -n ${value} > /sys/module/${modulename}/parameters/${parm}`.

The parameters listed below are only valid if certain kernel build options were enabled and if respective hardware is present. The text in square brackets at the beginning of each description states the restrictions within which a parameter is applicable:

    ACPI    ACPI support is enabled.
    AGP     AGP (Accelerated Graphics Port) is enabled.
    ALSA    ALSA sound support is enabled.
    APIC    APIC support is enabled.
    APM     Advanced Power Management support is enabled.
    ARM     ARM architecture is enabled.
    ARM64   ARM64 architecture is enabled.
    AX25    Appropriate AX.25 support is enabled.
    CLK     Common clock infrastructure is enabled.
    CMA     Contiguous Memory Area support is enabled.
    DRM     Direct Rendering Management support is enabled.
    DYNAMIC_DEBUG Build in debug messages and enable them at runtime
    EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
    EFI     EFI Partitioning (GPT) is enabled
    EIDE    EIDE/ATAPI support is enabled.
    EVM     Extended Verification Module
    FB      The frame buffer device is enabled.
    FTRACE  Function tracing enabled.
    GCOV    GCOV profiling is enabled.
    HW      Appropriate hardware is enabled.
    IA-64   IA-64 architecture is enabled.
    IMA     Integrity measurement architecture is enabled.
    IOSCHED More than one I/O scheduler is enabled.
    IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
    IPV6    IPv6 support is enabled.
    ISAPNP  ISA PnP code is enabled.
    ISDN    Appropriate ISDN support is enabled.
    ISOL    CPU Isolation is enabled.
    JOY     Appropriate joystick support is enabled.
    KGDB    Kernel debugger support is enabled.
    KVM     Kernel Virtual Machine support is enabled.
    LIBATA  Libata driver is enabled
    LP      Printer support is enabled.
    LOOP    Loopback device support is enabled.
    M68k    M68k architecture is enabled.
                    These options have more detailed description inside of
                    Documentation/m68k/kernel-options.rst.
    MDA     MDA console support is enabled.
    MIPS    MIPS architecture is enabled.
    MOUSE   Appropriate mouse support is enabled.
    MSI     Message Signaled Interrupts (PCI).
    MTD     MTD (Memory Technology Device) support is enabled.
    NET     Appropriate network support is enabled.
    NUMA    NUMA support is enabled.
    NFS     Appropriate NFS support is enabled.
    OF      Devicetree is enabled.
    OSS     OSS sound support is enabled.
    PV_OPS  A paravirtualized kernel is enabled.
    PARIDE  The ParIDE (parallel port IDE) subsystem is enabled.
    PARISC  The PA-RISC architecture is enabled.
    PCI     PCI bus support is enabled.
    PCIE    PCI Express support is enabled.
    PCMCIA  The PCMCIA subsystem is enabled.
    PNP     Plug & Play support is enabled.
    PPC     PowerPC architecture is enabled.
    PPT     Parallel port support is enabled.
    PS2     Appropriate PS/2 support is enabled.
    RAM     RAM disk support is enabled.
    RISCV   RISCV architecture is enabled.
    RDT     Intel Resource Director Technology.
    S390    S390 architecture is enabled.
    SCSI    Appropriate SCSI support is enabled.
                    A lot of drivers have their options described inside
                    the Documentation/scsi/ sub-directory.
    SECURITY Different security models are enabled.
    SELINUX SELinux support is enabled.
    APPARMOR AppArmor support is enabled.
    SERIAL  Serial support is enabled.
    SH      SuperH architecture is enabled.
    SMP     The kernel is an SMP kernel.
    SPARC   Sparc architecture is enabled.
    SWSUSP  Software suspend (hibernation) is enabled.
    SUSPEND System suspend states are enabled.
    TPM     TPM drivers are enabled.
    TS      Appropriate touchscreen support is enabled.
    UMS     USB Mass Storage support is enabled.
    USB     USB support is enabled.
    USBHID  USB Human Interface Device support is enabled.
    V4L     Video For Linux support is enabled.
    VMMIO   Driver for memory mapped virtio devices is enabled.
    VGA     The VGA console has been enabled.
    VT      Virtual terminal support is enabled.
    WDT     Watchdog support is enabled.
    XT      IBM PC/XT MFM hard disk support is enabled.
    X86-32  X86-32, aka i386 architecture is enabled.
    X86-64  X86-64 architecture is enabled.
                    More X86-64 boot options can be found in
                    Documentation/x86/x86_64/boot-options.rst.
    X86     Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
    X86_UV  SGI UV support is enabled.
    XEN     Xen support is enabled
    XTENSA  xtensa architecture is enabled.

In addition, the following text indicates that the option:

    BUGS=   Relates to possible processor bugs on the said processor.
    KNL     Is a kernel start-up parameter.
    BOOT    Is a boot loader parameter.

Parameters denoted with BOOT are actually interpreted by the boot loader, and have no meaning to the kernel directly. Do not modify the syntax of boot loader parameters without extreme need or coordination with <The Linux/x86 Boot Protocol>.

There are also arch-specific kernel-parameters not documented here. See for example <AMD64 Specific Boot Options>.

Note that ALL kernel parameters listed below are CASE SENSITIVE, and that a trailing = on the name of any parameter states that that parameter will be entered as an environment variable, whereas its absence indicates that it will appear as a kernel argument readable via /proc/cmdline by programs running once the system is up.

The number of kernel parameters is not limited, but the length of the complete command line (parameters including spaces etc.) is limited to a fixed number of characters. This limit depends on the architecture and is between 256 and 4096 characters. It is defined in the file ./include/asm/setup.h as COMMAND_LINE_SIZE.

Finally, the [KMG] suffix is commonly described after a number of kernel parameter values. These ‘K’, ‘M’, and ‘G’ letters represent the _binary_ multipliers ‘Kilo’, ‘Mega’, and ‘Giga’, equaling 2^10, 2^20, and 2^30 bytes respectively. Such letter suffixes can also be entirely omitted:

            acpi=           [HW,ACPI,X86,ARM64]
                            Advanced Configuration and Power Interface
                            Format: { force | on | off | strict | noirq | rsdt |
                                      copy_dsdt }
                            force -- enable ACPI if default was off
                            on -- enable ACPI but allow fallback to DT [arm64]
                            off -- disable ACPI if default was on
                            noirq -- do not use ACPI for IRQ routing
                            strict -- Be less tolerant of platforms that are not
                                    strictly ACPI specification compliant.
                            rsdt -- prefer RSDT over (default) XSDT
                            copy_dsdt -- copy DSDT to memory
                            For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
                            are available

                            See also Documentation/power/runtime_pm.rst, pci=noacpi

            acpi_apic_instance=     [ACPI, IOAPIC]
                            Format: <int>
                            2: use 2nd APIC table, if available
                            1,0: use 1st APIC table
                            default: 0

            acpi_backlight= [HW,ACPI]
                            { vendor | video | native | none }
                            If set to vendor, prefer vendor-specific driver
                            (e.g. thinkpad_acpi, sony_acpi, etc.) instead
                            of the ACPI video.ko driver.
                            If set to video, use the ACPI video.ko driver.
                            If set to native, use the device's native backlight mode.
                            If set to none, disable the ACPI backlight interface.

            acpi_force_32bit_fadt_addr
                            force FADT to use 32 bit addresses rather than the
                            64 bit X_* addresses. Some firmware have broken 64
                            bit addresses for force ACPI ignore these and use
                            the older legacy 32 bit addresses.

            acpica_no_return_repair [HW, ACPI]
                            Disable AML predefined validation mechanism
                            This mechanism can repair the evaluation result to make
                            the return objects more ACPI specification compliant.
                            This option is useful for developers to identify the
                            root cause of an AML interpreter issue when the issue
                            has something to do with the repair mechanism.

            acpi.debug_layer=       [HW,ACPI,ACPI_DEBUG]
            acpi.debug_level=       [HW,ACPI,ACPI_DEBUG]
                            Format: <int>
                            CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
                            debug output.  Bits in debug_layer correspond to a
                            _COMPONENT in an ACPI source file, e.g.,
                                #define _COMPONENT ACPI_EVENTS
                            Bits in debug_level correspond to a level in
                            ACPI_DEBUG_PRINT statements, e.g.,
                                ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
                            The debug_level mask defaults to "info".  See
                            Documentation/firmware-guide/acpi/debug.rst for more information about
                            debug layers and levels.

                            Enable processor driver info messages:
                                acpi.debug_layer=0x20000000
                            Enable AML "Debug" output, i.e., stores to the Debug
                            object while interpreting AML:
                                acpi.debug_layer=0xffffffff acpi.debug_level=0x2
                            Enable all messages related to ACPI hardware:
                                acpi.debug_layer=0x2 acpi.debug_level=0xffffffff

                            Some values produce so much output that the system is
                            unusable.  The "log_buf_len" parameter may be useful
                            if you need to capture more output.

            acpi_enforce_resources= [ACPI]
                            { strict | lax | no }
                            Check for resource conflicts between native drivers
                            and ACPI OperationRegions (SystemIO and SystemMemory
                            only). IO ports and memory declared in ACPI might be
                            used by the ACPI subsystem in arbitrary AML code and
                            can interfere with legacy drivers.
                            strict (default): access to resources claimed by ACPI
                            is denied; legacy drivers trying to access reserved
                            resources will fail to bind to device using them.
                            lax: access to resources claimed by ACPI is allowed;
                            legacy drivers trying to access reserved resources
                            will bind successfully but a warning message is logged.
                            no: ACPI OperationRegions are not marked as reserved,
                            no further checks are performed.

            acpi_force_table_verification   [HW,ACPI]
                            Enable table checksum verification during early stage.
                            By default, this is disabled due to x86 early mapping
                            size limitation.

            acpi_irq_balance [HW,ACPI]
                            ACPI will balance active IRQs
                            default in APIC mode

            acpi_irq_nobalance [HW,ACPI]
                            ACPI will not move active IRQs (default)
                            default in PIC mode

            acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
                            Format: <irq>,<irq>...

            acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
                            use by PCI
                            Format: <irq>,<irq>...

            acpi_mask_gpe=  [HW,ACPI]
                            Due to the existence of _Lxx/_Exx, some GPEs triggered
                            by unsupported hardware/firmware features can result in
                            GPE floodings that cannot be automatically disabled by
                            the GPE dispatcher.
                            This facility can be used to prevent such uncontrolled
                            GPE floodings.
                            Format: <byte> or <bitmap-list>

            acpi_no_auto_serialize  [HW,ACPI]
                            Disable auto-serialization of AML methods
                            AML control methods that contain the opcodes to create
                            named objects will be marked as "Serialized" by the
                            auto-serialization feature.
                            This feature is enabled by default.
                            This option allows to turn off the feature.

            acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
                               kernels.

            acpi_no_static_ssdt     [HW,ACPI]
                            Disable installation of static SSDTs at early boot time
                            By default, SSDTs contained in the RSDT/XSDT will be
                            installed automatically and they will appear under
                            /sys/firmware/acpi/tables.
                            This option turns off this feature.
                            Note that specifying this option does not affect
                            dynamic table installation which will install SSDT
                            tables to /sys/firmware/acpi/tables/dynamic.

            acpi_no_watchdog        [HW,ACPI,WDT]
                            Ignore the ACPI-based watchdog interface (WDAT) and let
                            a native driver control the watchdog device instead.

            acpi_rsdp=      [ACPI,EFI,KEXEC]
                            Pass the RSDP address to the kernel, mostly used
                            on machines running EFI runtime service to boot the
                            second kernel for kdump.

            acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
                            Format: To spoof as Windows 98: ="Microsoft Windows"

            acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
                            of 2 which is mandated by ACPI 6) as the supported ACPI
                            specification revision (when using this switch, it may
                            be necessary to carry out a cold reboot _twice_ in a
                            row to make it take effect on the platform firmware).

            acpi_osi=       [HW,ACPI] Modify list of supported OS interface strings
                            acpi_osi="string1"      # add string1
                            acpi_osi="!string2"     # remove string2
                            acpi_osi=!*             # remove all strings
                            acpi_osi=!              # disable all built-in OS vendor
                                                      strings
                            acpi_osi=!!             # enable all built-in OS vendor
                                                      strings
                            acpi_osi=               # disable all strings

                            'acpi_osi=!' can be used in combination with single or
                            multiple 'acpi_osi="string1"' to support specific OS
                            vendor string(s).  Note that such command can only
                            affect the default state of the OS vendor strings, thus
                            it cannot affect the default state of the feature group
                            strings and the current state of the OS vendor strings,
                            specifying it multiple times through kernel command line
                            is meaningless.  This command is useful when one do not
                            care about the state of the feature group strings which
                            should be controlled by the OSPM.
                            Examples:
                              1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
                                 to 'acpi_osi="Windows 2000" acpi_osi=!', they all
                                 can make '_OSI("Windows 2000")' TRUE.

                            'acpi_osi=' cannot be used in combination with other
                            'acpi_osi=' command lines, the _OSI method will not
                            exist in the ACPI namespace.  NOTE that such command can
                            only affect the _OSI support state, thus specifying it
                            multiple times through kernel command line is also
                            meaningless.
                            Examples:
                              1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
                                 FALSE.

                            'acpi_osi=!*' can be used in combination with single or
                            multiple 'acpi_osi="string1"' to support specific
                            string(s).  Note that such command can affect the
                            current state of both the OS vendor strings and the
                            feature group strings, thus specifying it multiple times
                            through kernel command line is meaningful.  But it may
                            still not able to affect the final state of a string if
                            there are quirks related to this string.  This command
                            is useful when one want to control the state of the
                            feature group strings to debug BIOS issues related to
                            the OSPM features.
                            Examples:
                              1. 'acpi_osi="Module Device" acpi_osi=!*' can make
                                 '_OSI("Module Device")' FALSE.
                              2. 'acpi_osi=!* acpi_osi="Module Device"' can make
                                 '_OSI("Module Device")' TRUE.
                              3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
                                 equivalent to
                                 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
                                 and
                                 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
                                 they all will make '_OSI("Windows 2000")' TRUE.

            acpi_pm_good    [X86]
                            Override the pmtimer bug detection: force the kernel
                            to assume that this machine's pmtimer latches its value
                            and always returns good values.

            acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
                            Format: { level | edge | high | low }

            acpi_skip_timer_override [HW,ACPI]
                            Recognize and ignore IRQ0/pin2 Interrupt Override.
                            For broken nForce2 BIOS resulting in XT-PIC timer.

            acpi_sleep=     [HW,ACPI] Sleep options
                            Format: { s3_bios, s3_mode, s3_beep, s4_hwsig,
                                      s4_nohwsig, old_ordering, nonvs,
                                      sci_force_enable, nobl }
                            See Documentation/power/video.rst for information on
                            s3_bios and s3_mode.
                            s3_beep is for debugging; it makes the PC's speaker beep
                            as soon as the kernel's real-mode entry point is called.
                            s4_hwsig causes the kernel to check the ACPI hardware
                            signature during resume from hibernation, and gracefully
                            refuse to resume if it has changed. This complies with
                            the ACPI specification but not with reality, since
                            Windows does not do this and many laptops do change it
                            on docking. So the default behaviour is to allow resume
                            and simply warn when the signature changes, unless the
                            s4_hwsig option is enabled.
                            s4_nohwsig prevents ACPI hardware signature from being
                            used (or even warned about) during resume.
                            old_ordering causes the ACPI 1.0 ordering of the _PTS
                            control method, with respect to putting devices into
                            low power states, to be enforced (the ACPI 2.0 ordering
                            of _PTS is used by default).
                            nonvs prevents the kernel from saving/restoring the
                            ACPI NVS memory during suspend/hibernation and resume.
                            sci_force_enable causes the kernel to set SCI_EN directly
                            on resume from S1/S3 (which is against the ACPI spec,
                            but some broken systems don't work without it).
                            nobl causes the internal blacklist of systems known to
                            behave incorrectly in some ways with respect to system
                            suspend and resume to be ignored (use wisely).

            acpi_use_timer_override [HW,ACPI]
                            Use timer override. For some broken Nvidia NF5 boards
                            that require a timer override, but don't have HPET

            add_efi_memmap  [EFI; X86] Include EFI memory map in
                            kernel's map of available physical RAM.

            agp=            [AGP]
                            { off | try_unsupported }
                            off: disable AGP support
                            try_unsupported: try to drive unsupported chipsets
                                    (may crash computer or cause data corruption)

            ALSA            [HW,ALSA]
                            See Documentation/sound/alsa-configuration.rst

            alignment=      [KNL,ARM]
                            Allow the default userspace alignment fault handler
                            behaviour to be specified.  Bit 0 enables warnings,
                            bit 1 enables fixups, and bit 2 sends a segfault.

            align_va_addr=  [X86-64]
                            Align virtual addresses by clearing slice [14:12] when
                            allocating a VMA at process creation time. This option
                            gives you up to 3% performance improvement on AMD F15h
                            machines (where it is enabled by default) for a
                            CPU-intensive style benchmark, and it can vary highly in
                            a microbenchmark depending on workload and compiler.

                            32: only for 32-bit processes
                            64: only for 64-bit processes
                            on: enable for both 32- and 64-bit processes
                            off: disable for both 32- and 64-bit processes

            alloc_snapshot  [FTRACE]
                            Allocate the ftrace snapshot buffer on boot up when the
                            main buffer is allocated. This is handy if debugging
                            and you need to use tracing_snapshot() on boot up, and
                            do not want to use tracing_snapshot_alloc() as it needs
                            to be done where GFP_KERNEL allocations are allowed.

            allow_mismatched_32bit_el0 [ARM64]
                            Allow execve() of 32-bit applications and setting of the
                            PER_LINUX32 personality on systems where only a strict
                            subset of the CPUs support 32-bit EL0. When this
                            parameter is present, the set of CPUs supporting 32-bit
                            EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
                            and hot-unplug operations may be restricted.

                            See Documentation/arm64/asymmetric-32bit.rst for more
                            information.

            amd_iommu=      [HW,X86-64]
                            Pass parameters to the AMD IOMMU driver in the system.
                            Possible values are:
                            fullflush - Deprecated, equivalent to iommu.strict=1
                            off       - do not initialize any AMD IOMMU found in
                                        the system
                            force_isolation - Force device isolation for all
                                              devices. The IOMMU driver is not
                                              allowed anymore to lift isolation
                                              requirements as needed. This option
                                              does not override iommu=pt
                            force_enable - Force enable the IOMMU on platforms known
                                           to be buggy with IOMMU enabled. Use this
                                           option with care.

            amd_iommu_dump= [HW,X86-64]
                            Enable AMD IOMMU driver option to dump the ACPI table
                            for AMD IOMMU. With this option enabled, AMD IOMMU
                            driver will print ACPI tables for AMD IOMMU during
                            IOMMU initialization.

            amd_iommu_intr= [HW,X86-64]
                            Specifies one of the following AMD IOMMU interrupt
                            remapping modes:
                            legacy     - Use legacy interrupt remapping mode.
                            vapic      - Use virtual APIC mode, which allows IOMMU
                                         to inject interrupts directly into guest.
                                         This mode requires kvm-amd.avic=1.
                                         (Default when IOMMU HW support is present.)

            amijoy.map=     [HW,JOY] Amiga joystick support
                            Map of devices attached to JOY0DAT and JOY1DAT
                            Format: <a>,<b>
                            See also Documentation/input/joydev/joystick.rst

            analog.map=     [HW,JOY] Analog joystick and gamepad support
                            Specifies type or capabilities of an analog joystick
                            connected to one of 16 gameports
                            Format: <type1>,<type2>,..<type16>

            apc=            [HW,SPARC]
                            Power management functions (SPARCstation-4/5 + deriv.)
                            Format: noidle
                            Disable APC CPU standby support. SPARCstation-Fox does
                            not play well with APC CPU idle - disable it if you have
                            APC and your system crashes randomly.

            apic=           [APIC,X86] Advanced Programmable Interrupt Controller
                            Change the output verbosity while booting
                            Format: { quiet (default) | verbose | debug }
                            Change the amount of debugging information output
                            when initialising the APIC and IO-APIC components.
                            For X86-32, this can also be used to specify an APIC
                            driver name.
                            Format: apic=driver_name
                            Examples: apic=bigsmp

            apic_extnmi=    [APIC,X86] External NMI delivery setting
                            Format: { bsp (default) | all | none }
                            bsp:  External NMI is delivered only to CPU 0
                            all:  External NMIs are broadcast to all CPUs as a
                                  backup of CPU 0
                            none: External NMI is masked for all CPUs. This is
                                  useful so that a dump capture kernel won't be
                                  shot down by NMI

            autoconf=       [IPV6]
                            See Documentation/networking/ipv6.rst.

            show_lapic=     [APIC,X86] Advanced Programmable Interrupt Controller
                            Limit apic dumping. The parameter defines the maximal
                            number of local apics being dumped. Also it is possible
                            to set it to "all" by meaning -- no limit here.
                            Format: { 1 (default) | 2 | ... | all }.
                            The parameter valid if only apic=debug or
                            apic=verbose is specified.
                            Example: apic=debug show_lapic=all

            apm=            [APM] Advanced Power Management
                            See header of arch/x86/kernel/apm_32.c.

            arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
                            Format: <io>,<irq>,<nodeID>

            arm64.nobti     [ARM64] Unconditionally disable Branch Target
                            Identification support

            arm64.nopauth   [ARM64] Unconditionally disable Pointer Authentication
                            support

            arm64.nomte     [ARM64] Unconditionally disable Memory Tagging Extension
                            support

            ataflop=        [HW,M68k]

            atarimouse=     [HW,MOUSE] Atari Mouse

            atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
                            EzKey and similar keyboards

            atkbd.reset=    [HW] Reset keyboard during initialization

            atkbd.set=      [HW] Select keyboard code set
                            Format: <int> (2 = AT (default), 3 = PS/2)

            atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
                            keyboards

            atkbd.softraw=  [HW] Choose between synthetic and real raw mode
                            Format: <bool> (0 = real, 1 = synthetic (default))

            atkbd.softrepeat= [HW]
                            Use software keyboard repeat

            audit=          [KNL] Enable the audit sub-system
                            Format: { "0" | "1" | "off" | "on" }
                            0 | off - kernel audit is disabled and can not be
                                enabled until the next reboot
                            unset - kernel audit is initialized but disabled and
                                will be fully enabled by the userspace auditd.
                            1 | on - kernel audit is initialized and partially
                                enabled, storing at most audit_backlog_limit
                                messages in RAM until it is fully enabled by the
                                userspace auditd.
                            Default: unset

            audit_backlog_limit= [KNL] Set the audit queue size limit.
                            Format: <int> (must be >=0)
                            Default: 64

            bau=            [X86_UV] Enable the BAU on SGI UV.  The default
                            behavior is to disable the BAU (i.e. bau=0).
                            Format: { "0" | "1" }
                            0 - Disable the BAU.
                            1 - Enable the BAU.
                            unset - Disable the BAU.

            baycom_epp=     [HW,AX25]
                            Format: <io>,<mode>

            baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
                            Format: <io>,<mode>
                            See header of drivers/net/hamradio/baycom_par.c.

            baycom_ser_fdx= [HW,AX25]
                            BayCom Serial Port AX.25 Modem (Full Duplex Mode)
                            Format: <io>,<irq>,<mode>[,<baud>]
                            See header of drivers/net/hamradio/baycom_ser_fdx.c.

            baycom_ser_hdx= [HW,AX25]
                            BayCom Serial Port AX.25 Modem (Half Duplex Mode)
                            Format: <io>,<irq>,<mode>
                            See header of drivers/net/hamradio/baycom_ser_hdx.c.

            blkdevparts=    Manual partition parsing of block device(s) for
                            embedded devices based on command line input.
                            See Documentation/block/cmdline-partition.rst

            boot_delay=     Milliseconds to delay each printk during boot.
                            Values larger than 10 seconds (10000) are changed to
                            no delay (0).
                            Format: integer

            bootconfig      [KNL]
                            Extended command line options can be added to an initrd
                            and this will cause the kernel to look for it.

                            See Documentation/admin-guide/bootconfig.rst

            bert_disable    [ACPI]
                            Disable BERT OS support on buggy BIOSes.

            bgrt_disable    [ACPI][X86]
                            Disable BGRT to avoid flickering OEM logo.

            bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
            bttv.radio=     Most important insmod options are available as
                            kernel args too.
            bttv.pll=       See Documentation/admin-guide/media/bttv.rst
            bttv.tuner=

            bulk_remove=off [PPC]  This parameter disables the use of the pSeries
                            firmware feature for flushing multiple hpte entries
                            at a time.

            c101=           [NET] Moxa C101 synchronous serial card

            cachesize=      [BUGS=X86-32] Override level 2 CPU cache size detection.
                            Sometimes CPU hardware bugs make them report the cache
                            size incorrectly. The kernel will attempt work arounds
                            to fix known problems, but for some CPUs it is not
                            possible to determine what the correct size should be.
                            This option provides an override for these situations.

            carrier_timeout=
                            [NET] Specifies amount of time (in seconds) that
                            the kernel should wait for a network carrier. By default
                            it waits 120 seconds.

            ca_keys=        [KEYS] This parameter identifies a specific key(s) on
                            the system trusted keyring to be used for certificate
                            trust validation.
                            format: { id:<keyid> | builtin }

            cca=            [MIPS] Override the kernel pages' cache coherency
                            algorithm.  Accepted values range from 0 to 7
                            inclusive. See arch/mips/include/asm/pgtable-bits.h
                            for platform specific values (SB1, Loongson3 and
                            others).

            ccw_timeout_log [S390]
                            See Documentation/s390/common_io.rst for details.

            cgroup_disable= [KNL] Disable a particular controller or optional feature
                            Format: {name of the controller(s) or feature(s) to disable}
                            The effects of cgroup_disable=foo are:
                            - foo isn't auto-mounted if you mount all cgroups in
                              a single hierarchy
                            - foo isn't visible as an individually mountable
                              subsystem
                            - if foo is an optional feature then the feature is
                              disabled and corresponding cgroup files are not
                              created
                            {Currently only "memory" controller deal with this and
                            cut the overhead, others just disable the usage. So
                            only cgroup_disable=memory is actually worthy}
                            Specifying "pressure" disables per-cgroup pressure
                            stall information accounting feature

            cgroup_no_v1=   [KNL] Disable cgroup controllers and named hierarchies in v1
                            Format: { { controller | "all" | "named" }
                                      [,{ controller | "all" | "named" }...] }
                            Like cgroup_disable, but only applies to cgroup v1;
                            the blacklisted controllers remain available in cgroup2.
                            "all" blacklists all controllers and "named" disables
                            named mounts. Specifying both "all" and "named" disables
                            all v1 hierarchies.

            cgroup.memory=  [KNL] Pass options to the cgroup memory controller.
                            Format: <string>
                            nosocket -- Disable socket memory accounting.
                            nokmem -- Disable kernel memory accounting.

            checkreqprot    [SELINUX] Set initial checkreqprot flag value.
                            Format: { "0" | "1" }
                            See security/selinux/Kconfig help text.
                            0 -- check protection applied by kernel (includes
                                    any implied execute protection).
                            1 -- check protection requested by application.
                            Default value is set via a kernel config option.
                            Value can be changed at runtime via
                                    /sys/fs/selinux/checkreqprot.
                            Setting checkreqprot to 1 is deprecated.

            cio_ignore=     [S390]
                            See Documentation/s390/common_io.rst for details.
            clk_ignore_unused
                            [CLK]
                            Prevents the clock framework from automatically gating
                            clocks that have not been explicitly enabled by a Linux
                            device driver but are enabled in hardware at reset or
                            by the bootloader/firmware. Note that this does not
                            force such clocks to be always-on nor does it reserve
                            those clocks in any way. This parameter is useful for
                            debug and development, but should not be needed on a
                            platform with proper driver support.  For more
                            information, see Documentation/driver-api/clk.rst.

            clock=          [BUGS=X86-32, HW] gettimeofday clocksource override.
                            [Deprecated]
                            Forces specified clocksource (if available) to be used
                            when calculating gettimeofday(). If specified
                            clocksource is not available, it defaults to PIT.
                            Format: { pit | tsc | cyclone | pmtmr }

            clocksource=    Override the default clocksource
                            Format: <string>
                            Override the default clocksource and use the clocksource
                            with the name specified.
                            Some clocksource names to choose from, depending on
                            the platform:
                            [all] jiffies (this is the base, fallback clocksource)
                            [ACPI] acpi_pm
                            [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
                                    pxa_timer,timer3,32k_counter,timer0_1
                            [X86-32] pit,hpet,tsc;
                                    scx200_hrt on Geode; cyclone on IBM x440
                            [MIPS] MIPS
                            [PARISC] cr16
                            [S390] tod
                            [SH] SuperH
                            [SPARC64] tick
                            [X86-64] hpet,tsc

            clocksource.arm_arch_timer.evtstrm=
                            [ARM,ARM64]
                            Format: <bool>
                            Enable/disable the eventstream feature of the ARM
                            architected timer so that code using WFE-based polling
                            loops can be debugged more effectively on production
                            systems.

            clocksource.max_cswd_read_retries= [KNL]
                            Number of clocksource_watchdog() retries due to
                            external delays before the clock will be marked
                            unstable.  Defaults to two retries, that is,
                            three attempts to read the clock under test.

            clocksource.verify_n_cpus= [KNL]
                            Limit the number of CPUs checked for clocksources
                            marked with CLOCK_SOURCE_VERIFY_PERCPU that
                            are marked unstable due to excessive skew.
                            A negative value says to check all CPUs, while
                            zero says not to check any.  Values larger than
                            nr_cpu_ids are silently truncated to nr_cpu_ids.
                            The actual CPUs are chosen randomly, with
                            no replacement if the same CPU is chosen twice.

            clocksource-wdtest.holdoff= [KNL]
                            Set the time in seconds that the clocksource
                            watchdog test waits before commencing its tests.
                            Defaults to zero when built as a module and to
                            10 seconds when built into the kernel.

            clearcpuid=BITNUM[,BITNUM...] [X86]
                            Disable CPUID feature X for the kernel. See
                            arch/x86/include/asm/cpufeatures.h for the valid bit
                            numbers. Note the Linux specific bits are not necessarily
                            stable over kernel options, but the vendor specific
                            ones should be.
                            Also note that user programs calling CPUID directly
                            or using the feature without checking anything
                            will still see it. This just prevents it from
                            being used by the kernel or shown in /proc/cpuinfo.
                            Also note the kernel might malfunction if you disable
                            some critical bits.

            cma=nn[MG]@[start[MG][-end[MG]]]
                            [KNL,CMA]
                            Sets the size of kernel global memory area for
                            contiguous memory allocations and optionally the
                            placement constraint by the physical address range of
                            memory allocations. A value of 0 disables CMA
                            altogether. For more information, see
                            kernel/dma/contiguous.c

            cma_pernuma=nn[MG]
                            [ARM64,KNL,CMA]
                            Sets the size of kernel per-numa memory area for
                            contiguous memory allocations. A value of 0 disables
                            per-numa CMA altogether. And If this option is not
                            specificed, the default value is 0.
                            With per-numa CMA enabled, DMA users on node nid will
                            first try to allocate buffer from the pernuma area
                            which is located in node nid, if the allocation fails,
                            they will fallback to the global default memory area.

            cmo_free_hint=  [PPC] Format: { yes | no }
                            Specify whether pages are marked as being inactive
                            when they are freed.  This is used in CMO environments
                            to determine OS memory pressure for page stealing by
                            a hypervisor.
                            Default: yes

            coherent_pool=nn[KMG]   [ARM,KNL]
                            Sets the size of memory pool for coherent, atomic dma
                            allocations, by default set to 256K.

            com20020=       [HW,NET] ARCnet - COM20020 chipset
                            Format:
                            <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]

            com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
                            Format: <io>[,<irq>]

            com90xx=        [HW,NET]
                            ARCnet - COM90xx chipset (memory-mapped buffers)
                            Format: <io>[,<irq>[,<memstart>]]

            condev=         [HW,S390] console device
            conmode=

            console=        [KNL] Output console device and options.

                    tty<n>  Use the virtual console device <n>.

                    ttyS<n>[,options]
                    ttyUSB0[,options]
                            Use the specified serial port.  The options are of
                            the form "bbbbpnf", where "bbbb" is the baud rate,
                            "p" is parity ("n", "o", or "e"), "n" is number of
                            bits, and "f" is flow control ("r" for RTS or
                            omit it).  Default is "9600n8".

                            See Documentation/admin-guide/serial-console.rst for more
                            information.  See
                            Documentation/networking/netconsole.rst for an
                            alternative.

                    uart[8250],io,<addr>[,options]
                    uart[8250],mmio,<addr>[,options]
                    uart[8250],mmio16,<addr>[,options]
                    uart[8250],mmio32,<addr>[,options]
                    uart[8250],0x<addr>[,options]
                            Start an early, polled-mode console on the 8250/16550
                            UART at the specified I/O port or MMIO address,
                            switching to the matching ttyS device later.
                            MMIO inter-register address stride is either 8-bit
                            (mmio), 16-bit (mmio16), or 32-bit (mmio32).
                            If none of [io|mmio|mmio16|mmio32], <addr> is assumed
                            to be equivalent to 'mmio'. 'options' are specified in
                            the same format described for ttyS above; if unspecified,
                            the h/w is not re-initialized.

                    hvc<n>  Use the hypervisor console device <n>. This is for
                            both Xen and PowerPC hypervisors.

                    { null | "" }
                            Use to disable console output, i.e., to have kernel
                            console messages discarded.
                            This must be the only console= parameter used on the
                            kernel command line.

                    If the device connected to the port is not a TTY but a braille
                    device, prepend "brl," before the device type, for instance
                            console=brl,ttyS0
                    For now, only VisioBraille is supported.

            console_msg_format=
                            [KNL] Change console messages format
                    default
                            By default we print messages on consoles in
                            "[time stamp] text\n" format (time stamp may not be
                            printed, depending on CONFIG_PRINTK_TIME or
                            `printk_time' param).
                    syslog
                            Switch to syslog format: "<%u>[time stamp] text\n"
                            IOW, each message will have a facility and loglevel
                            prefix. The format is similar to one used by syslog()
                            syscall, or to executing "dmesg -S --raw" or to reading
                            from /proc/kmsg.

            consoleblank=   [KNL] The console blank (screen saver) timeout in
                            seconds. A value of 0 disables the blank timer.
                            Defaults to 0.

            coredump_filter=
                            [KNL] Change the default value for
                            /proc/<pid>/coredump_filter.
                            See also Documentation/filesystems/proc.rst.

            coresight_cpu_debug.enable
                            [ARM,ARM64]
                            Format: <bool>
                            Enable/disable the CPU sampling based debugging.
                            0: default value, disable debugging
                            1: enable debugging at boot time

            cpuidle.off=1   [CPU_IDLE]
                            disable the cpuidle sub-system

            cpuidle.governor=
                            [CPU_IDLE] Name of the cpuidle governor to use.

            cpufreq.off=1   [CPU_FREQ]
                            disable the cpufreq sub-system

            cpufreq.default_governor=
                            [CPU_FREQ] Name of the default cpufreq governor or
                            policy to use. This governor must be registered in the
                            kernel before the cpufreq driver probes.

            cpu_init_udelay=N
                            [X86] Delay for N microsec between assert and de-assert
                            of APIC INIT to start processors.  This delay occurs
                            on every CPU online, such as boot, and resume from suspend.
                            Default: 10000

            cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
                            Format:
                            <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

            crashkernel=size[KMG][@offset[KMG]]
                            [KNL] Using kexec, Linux can switch to a 'crash kernel'
                            upon panic. This parameter reserves the physical
                            memory region [offset, offset + size] for that kernel
                            image. If '@offset' is omitted, then a suitable offset
                            is selected automatically.
                            [KNL, X86-64] Select a region under 4G first, and
                            fall back to reserve region above 4G when '@offset'
                            hasn't been specified.
                            See Documentation/admin-guide/kdump/kdump.rst for further details.

            crashkernel=range1:size1[,range2:size2,...][@offset]
                            [KNL] Same as above, but depends on the memory
                            in the running system. The syntax of range is
                            start-[end] where start and end are both
                            a memory unit (amount[KMG]). See also
                            Documentation/admin-guide/kdump/kdump.rst for an example.

            crashkernel=size[KMG],high
                            [KNL, X86-64] range could be above 4G. Allow kernel
                            to allocate physical memory region from top, so could
                            be above 4G if system have more than 4G ram installed.
                            Otherwise memory region will be allocated below 4G, if
                            available.
                            It will be ignored if crashkernel=X is specified.
            crashkernel=size[KMG],low
                            [KNL, X86-64] range under 4G. When crashkernel=X,high
                            is passed, kernel could allocate physical memory region
                            above 4G, that cause second kernel crash on system
                            that require some amount of low memory, e.g. swiotlb
                            requires at least 64M+32K low memory, also enough extra
                            low memory is needed to make sure DMA buffers for 32-bit
                            devices won't run out. Kernel would try to allocate at
                            at least 256M below 4G automatically.
                            This one let user to specify own low range under 4G
                            for second kernel instead.
                            0: to disable low allocation.
                            It will be ignored when crashkernel=X,high is not used
                            or memory reserved is below 4G.

            cryptomgr.notests
                            [KNL] Disable crypto self-tests

            cs89x0_dma=     [HW,NET]
                            Format: <dma>

            cs89x0_media=   [HW,NET]
                            Format: { rj45 | aui | bnc }

            csdlock_debug=  [KNL] Enable debug add-ons of cross-CPU function call
                            handling. When switched on, additional debug data is
                            printed to the console in case a hanging CPU is
                            detected, and that CPU is pinged again in order to try
                            to resolve the hang situation.
                            0: disable csdlock debugging (default)
                            1: enable basic csdlock debugging (minor impact)
                            ext: enable extended csdlock debugging (more impact,
                                 but more data)

            dasd=           [HW,NET]
                            See header of drivers/s390/block/dasd_devmap.c.

            db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
                            (one device per port)
                            Format: <port#>,<type>
                            See also Documentation/input/devices/joystick-parport.rst

            debug           [KNL] Enable kernel debugging (events log level).

            debug_boot_weak_hash
                            [KNL] Enable printing [hashed] pointers early in the
                            boot sequence.  If enabled, we use a weak hash instead
                            of siphash to hash pointers.  Use this option if you are
                            seeing instances of '(___ptrval___)') and need to see a
                            value (hashed pointer) instead. Cryptographically
                            insecure, please do not use on production kernels.

            debug_locks_verbose=
                            [KNL] verbose locking self-tests
                            Format: <int>
                            Print debugging info while doing the locking API
                            self-tests.
                            Bitmask for the various LOCKTYPE_ tests. Defaults to 0
                            (no extra messages), setting it to -1 (all bits set)
                            will print _a_lot_ more information - normally only
                            useful to lockdep developers.

            debug_objects   [KNL] Enable object debugging

            no_debug_objects
                            [KNL] Disable object debugging

            debug_guardpage_minorder=
                            [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
                            parameter allows control of the order of pages that will
                            be intentionally kept free (and hence protected) by the
                            buddy allocator. Bigger value increase the probability
                            of catching random memory corruption, but reduce the
                            amount of memory for normal system use. The maximum
                            possible value is MAX_ORDER/2.  Setting this parameter
                            to 1 or 2 should be enough to identify most random
                            memory corruption problems caused by bugs in kernel or
                            driver code when a CPU writes to (or reads from) a
                            random memory location. Note that there exists a class
                            of memory corruptions problems caused by buggy H/W or
                            F/W or by drivers badly programing DMA (basically when
                            memory is written at bus level and the CPU MMU is
                            bypassed) which are not detectable by
                            CONFIG_DEBUG_PAGEALLOC, hence this option will not help
                            tracking down these problems.

            debug_pagealloc=
                            [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
                            enables the feature at boot time. By default, it is
                            disabled and the system will work mostly the same as a
                            kernel built without CONFIG_DEBUG_PAGEALLOC.
                            Note: to get most of debug_pagealloc error reports, it's
                            useful to also enable the page_owner functionality.
                            on: enable the feature

            debugfs=        [KNL] This parameter enables what is exposed to userspace
                            and debugfs internal clients.
                            Format: { on, no-mount, off }
                            on:     All functions are enabled.
                            no-mount:
                                    Filesystem is not registered but kernel clients can
                                    access APIs and a crashkernel can be used to read
                                    its content. There is nothing to mount.
                            off:    Filesystem is not registered and clients
                                    get a -EPERM as result when trying to register files
                                    or directories within debugfs.
                                    This is equivalent of the runtime functionality if
                                    debugfs was not enabled in the kernel at all.
                            Default value is set in build-time with a kernel configuration.

            debugpat        [X86] Enable PAT debugging

            decnet.addr=    [HW,NET]
                            Format: <area>[,<node>]
                            See also Documentation/networking/decnet.rst.

            default_hugepagesz=
                            [HW] The size of the default HugeTLB page. This is
                            the size represented by the legacy /proc/ hugepages
                            APIs.  In addition, this is the default hugetlb size
                            used for shmget(), mmap() and mounting hugetlbfs
                            filesystems.  If not specified, defaults to the
                            architecture's default huge page size.  Huge page
                            sizes are architecture dependent.  See also
                            Documentation/admin-guide/mm/hugetlbpage.rst.
                            Format: size[KMG]

            deferred_probe_timeout=
                            [KNL] Debugging option to set a timeout in seconds for
                            deferred probe to give up waiting on dependencies to
                            probe. Only specific dependencies (subsystems or
                            drivers) that have opted in will be ignored. A timeout of 0
                            will timeout at the end of initcalls. This option will also
                            dump out devices still on the deferred probe list after
                            retrying.

            dell_smm_hwmon.ignore_dmi=
                            [HW] Continue probing hardware even if DMI data
                            indicates that the driver is running on unsupported
                            hardware.

            dell_smm_hwmon.force=
                            [HW] Activate driver even if SMM BIOS signature does
                            not match list of supported models and enable otherwise
                            blacklisted features.

            dell_smm_hwmon.power_status=
                            [HW] Report power status in /proc/i8k
                            (disabled by default).

            dell_smm_hwmon.restricted=
                            [HW] Allow controlling fans only if SYS_ADMIN
                            capability is set.

            dell_smm_hwmon.fan_mult=
                            [HW] Factor to multiply fan speed with.

            dell_smm_hwmon.fan_max=
                            [HW] Maximum configurable fan speed.

            dfltcc=         [HW,S390]
                            Format: { on | off | def_only | inf_only | always }
                            on:       s390 zlib hardware support for compression on
                                      level 1 and decompression (default)
                            off:      No s390 zlib hardware support
                            def_only: s390 zlib hardware support for deflate
                                      only (compression on level 1)
                            inf_only: s390 zlib hardware support for inflate
                                      only (decompression)
                            always:   Same as 'on' but ignores the selected compression
                                      level always using hardware support (used for debugging)

            dhash_entries=  [KNL]
                            Set number of hash buckets for dentry cache.

            disable_1tb_segments [PPC]
                            Disables the use of 1TB hash page table segments. This
                            causes the kernel to fall back to 256MB segments which
                            can be useful when debugging issues that require an SLB
                            miss to occur.

            stress_slb      [PPC]
                            Limits the number of kernel SLB entries, and flushes
                            them frequently to increase the rate of SLB faults
                            on kernel addresses.

            disable=        [IPV6]
                            See Documentation/networking/ipv6.rst.

            hardened_usercopy=
                            [KNL] Under CONFIG_HARDENED_USERCOPY, whether
                            hardening is enabled for this boot. Hardened
                            usercopy checking is used to protect the kernel
                            from reading or writing beyond known memory
                            allocation boundaries as a proactive defense
                            against bounds-checking flaws in the kernel's
                            copy_to_user()/copy_from_user() interface.
                    on      Perform hardened usercopy checks (default).
                    off     Disable hardened usercopy checks.

            disable_radix   [PPC]
                            Disable RADIX MMU mode on POWER9

            radix_hcall_invalidate=on  [PPC/PSERIES]
                            Disable RADIX GTSE feature and use hcall for TLB
                            invalidate.

            disable_tlbie   [PPC]
                            Disable TLBIE instruction. Currently does not work
                            with KVM, with HASH MMU, or with coherent accelerators.

            disable_cpu_apicid= [X86,APIC,SMP]
                            Format: <int>
                            The number of initial APIC ID for the
                            corresponding CPU to be disabled at boot,
                            mostly used for the kdump 2nd kernel to
                            disable BSP to wake up multiple CPUs without
                            causing system reset or hang due to sending
                            INIT from AP to BSP.

            disable_ddw     [PPC/PSERIES]
                            Disable Dynamic DMA Window support. Use this
                            to workaround buggy firmware.

            disable_ipv6=   [IPV6]
                            See Documentation/networking/ipv6.rst.

            disable_mtrr_cleanup [X86]
                            The kernel tries to adjust MTRR layout from continuous
                            to discrete, to make X server driver able to add WB
                            entry later. This parameter disables that.

            disable_mtrr_trim [X86, Intel and AMD only]
                            By default the kernel will trim any uncacheable
                            memory out of your available memory pool based on
                            MTRR settings.  This parameter disables that behavior,
                            possibly causing your machine to run very slowly.

            disable_timer_pin_1 [X86]
                            Disable PIN 1 of APIC timer
                            Can be useful to work around chipset bugs.

            dis_ucode_ldr   [X86] Disable the microcode loader.

            dma_debug=off   If the kernel is compiled with DMA_API_DEBUG support,
                            this option disables the debugging code at boot.

            dma_debug_entries=<number>
                            This option allows to tune the number of preallocated
                            entries for DMA-API debugging code. One entry is
                            required per DMA-API allocation. Use this if the
                            DMA-API debugging code disables itself because the
                            architectural default is too low.

            dma_debug_driver=<driver_name>
                            With this option the DMA-API debugging driver
                            filter feature can be enabled at boot time. Just
                            pass the driver to filter for as the parameter.
                            The filter can be disabled or changed to another
                            driver later using sysfs.

            driver_async_probe=  [KNL]
                            List of driver names to be probed asynchronously.
                            Format: <driver_name1>,<driver_name2>...

            drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
                            Broken monitors, graphic adapters, KVMs and EDIDless
                            panels may send no or incorrect EDID data sets.
                            This parameter allows to specify an EDID data sets
                            in the /lib/firmware directory that are used instead.
                            Generic built-in EDID data sets are used, if one of
                            edid/1024x768.bin, edid/1280x1024.bin,
                            edid/1680x1050.bin, or edid/1920x1080.bin is given
                            and no file with the same name exists. Details and
                            instructions how to build your own EDID data are
                            available in Documentation/admin-guide/edid.rst. An EDID
                            data set will only be used for a particular connector,
                            if its name and a colon are prepended to the EDID
                            name. Each connector may use a unique EDID data
                            set by separating the files with a comma.  An EDID
                            data set with no connector name will be used for
                            any connectors not explicitly specified.

            dscc4.setup=    [NET]

            dt_cpu_ftrs=    [PPC]
                            Format: {"off" | "known"}
                            Control how the dt_cpu_ftrs device-tree binding is
                            used for CPU feature discovery and setup (if it
                            exists).
                            off: Do not use it, fall back to legacy cpu table.
                            known: Do not pass through unknown features to guests
                            or userspace, only those that the kernel is aware of.

            dump_apple_properties   [X86]
                            Dump name and content of EFI device properties on
                            x86 Macs.  Useful for driver authors to determine
                            what data is available or for reverse-engineering.

            dyndbg[="val"]          [KNL,DYNAMIC_DEBUG]
            <module>.dyndbg[="val"]
                            Enable debug messages at boot time.  See
                            Documentation/admin-guide/dynamic-debug-howto.rst
                            for details.

            nopku           [X86] Disable Memory Protection Keys CPU feature found
                            in some Intel CPUs.

            <module>.async_probe [KNL]
                            Enable asynchronous probe on this module.

            early_ioremap_debug [KNL]
                            Enable debug messages in early_ioremap support. This
                            is useful for tracking down temporary early mappings
                            which are not unmapped.

            earlycon=       [KNL] Output early console device and options.

                            When used with no options, the early console is
                            determined by stdout-path property in device tree's
                            chosen node or the ACPI SPCR table if supported by
                            the platform.

                    cdns,<addr>[,options]
                            Start an early, polled-mode console on a Cadence
                            (xuartps) serial port at the specified address. Only
                            supported option is baud rate. If baud rate is not
                            specified, the serial port must already be setup and
                            configured.

                    uart[8250],io,<addr>[,options]
                    uart[8250],mmio,<addr>[,options]
                    uart[8250],mmio32,<addr>[,options]
                    uart[8250],mmio32be,<addr>[,options]
                    uart[8250],0x<addr>[,options]
                            Start an early, polled-mode console on the 8250/16550
                            UART at the specified I/O port or MMIO address.
                            MMIO inter-register address stride is either 8-bit
                            (mmio) or 32-bit (mmio32 or mmio32be).
                            If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
                            to be equivalent to 'mmio'. 'options' are specified
                            in the same format described for "console=ttyS<n>"; if
                            unspecified, the h/w is not initialized.

                    pl011,<addr>
                    pl011,mmio32,<addr>
                            Start an early, polled-mode console on a pl011 serial
                            port at the specified address. The pl011 serial port
                            must already be setup and configured. Options are not
                            yet supported.  If 'mmio32' is specified, then only
                            the driver will use only 32-bit accessors to read/write
                            the device registers.

                    liteuart,<addr>
                            Start an early console on a litex serial port at the
                            specified address. The serial port must already be
                            setup and configured. Options are not yet supported.

                    meson,<addr>
                            Start an early, polled-mode console on a meson serial
                            port at the specified address. The serial port must
                            already be setup and configured. Options are not yet
                            supported.

                    msm_serial,<addr>
                            Start an early, polled-mode console on an msm serial
                            port at the specified address. The serial port
                            must already be setup and configured. Options are not
                            yet supported.

                    msm_serial_dm,<addr>
                            Start an early, polled-mode console on an msm serial
                            dm port at the specified address. The serial port
                            must already be setup and configured. Options are not
                            yet supported.

                    owl,<addr>
                            Start an early, polled-mode console on a serial port
                            of an Actions Semi SoC, such as S500 or S900, at the
                            specified address. The serial port must already be
                            setup and configured. Options are not yet supported.

                    rda,<addr>
                            Start an early, polled-mode console on a serial port
                            of an RDA Micro SoC, such as RDA8810PL, at the
                            specified address. The serial port must already be
                            setup and configured. Options are not yet supported.

                    sbi
                            Use RISC-V SBI (Supervisor Binary Interface) for early
                            console.

                    smh     Use ARM semihosting calls for early console.

                    s3c2410,<addr>
                    s3c2412,<addr>
                    s3c2440,<addr>
                    s3c6400,<addr>
                    s5pv210,<addr>
                    exynos4210,<addr>
                            Use early console provided by serial driver available
                            on Samsung SoCs, requires selecting proper type and
                            a correct base address of the selected UART port. The
                            serial port must already be setup and configured.
                            Options are not yet supported.

                    lantiq,<addr>
                            Start an early, polled-mode console on a lantiq serial
                            (lqasc) port at the specified address. The serial port
                            must already be setup and configured. Options are not
                            yet supported.

                    lpuart,<addr>
                    lpuart32,<addr>
                            Use early console provided by Freescale LP UART driver
                            found on Freescale Vybrid and QorIQ LS1021A processors.
                            A valid base address must be provided, and the serial
                            port must already be setup and configured.

                    ec_imx21,<addr>
                    ec_imx6q,<addr>
                            Start an early, polled-mode, output-only console on the
                            Freescale i.MX UART at the specified address. The UART
                            must already be setup and configured.

                    ar3700_uart,<addr>
                            Start an early, polled-mode console on the
                            Armada 3700 serial port at the specified
                            address. The serial port must already be setup
                            and configured. Options are not yet supported.

                    qcom_geni,<addr>
                            Start an early, polled-mode console on a Qualcomm
                            Generic Interface (GENI) based serial port at the
                            specified address. The serial port must already be
                            setup and configured. Options are not yet supported.

                    efifb,[options]
                            Start an early, unaccelerated console on the EFI
                            memory mapped framebuffer (if available). On cache
                            coherent non-x86 systems that use system memory for
                            the framebuffer, pass the 'ram' option so that it is
                            mapped with the correct attributes.

                    linflex,<addr>
                            Use early console provided by Freescale LINFlexD UART
                            serial driver for NXP S32V234 SoCs. A valid base
                            address must be provided, and the serial port must
                            already be setup and configured.

            earlyprintk=    [X86,SH,ARM,M68k,S390]
                            earlyprintk=vga
                            earlyprintk=sclp
                            earlyprintk=xen
                            earlyprintk=serial[,ttySn[,baudrate]]
                            earlyprintk=serial[,0x...[,baudrate]]
                            earlyprintk=ttySn[,baudrate]
                            earlyprintk=dbgp[debugController#]
                            earlyprintk=pciserial[,force],bus:device.function[,baudrate]
                            earlyprintk=xdbc[xhciController#]

                            earlyprintk is useful when the kernel crashes before
                            the normal console is initialized. It is not enabled by
                            default because it has some cosmetic problems.

                            Append ",keep" to not disable it when the real console
                            takes over.

                            Only one of vga, efi, serial, or usb debug port can
                            be used at a time.

                            Currently only ttyS0 and ttyS1 may be specified by
                            name.  Other I/O ports may be explicitly specified
                            on some architectures (x86 and arm at least) by
                            replacing ttySn with an I/O port address, like this:
                                    earlyprintk=serial,0x1008,115200
                            You can find the port for a given device in
                            /proc/tty/driver/serial:
                                    2: uart:ST16650V2 port:00001008 irq:18 ...

                            Interaction with the standard serial driver is not
                            very good.

                            The VGA and EFI output is eventually overwritten by
                            the real console.

                            The xen option can only be used in Xen domains.

                            The sclp output can only be used on s390.

                            The optional "force" to "pciserial" enables use of a
                            PCI device even when its classcode is not of the
                            UART class.

            edac_report=    [HW,EDAC] Control how to report EDAC event
                            Format: {"on" | "off" | "force"}
                            on: enable EDAC to report H/W event. May be overridden
                            by other higher priority error reporting module.
                            off: disable H/W event reporting through EDAC.
                            force: enforce the use of EDAC to report H/W event.
                            default: on.

            ekgdboc=        [X86,KGDB] Allow early kernel console debugging
                            ekgdboc=kbd

                            This is designed to be used in conjunction with
                            the boot argument: earlyprintk=vga

                            This parameter works in place of the kgdboc parameter
                            but can only be used if the backing tty is available
                            very early in the boot process. For early debugging
                            via a serial port see kgdboc_earlycon instead.

            edd=            [EDD]
                            Format: {"off" | "on" | "skip[mbr]"}

            efi=            [EFI]
                            Format: { "debug", "disable_early_pci_dma",
                                      "nochunk", "noruntime", "nosoftreserve",
                                      "novamap", "no_disable_early_pci_dma" }
                            debug: enable misc debug output.
                            disable_early_pci_dma: disable the busmaster bit on all
                            PCI bridges while in the EFI boot stub.
                            nochunk: disable reading files in "chunks" in the EFI
                            boot stub, as chunking can cause problems with some
                            firmware implementations.
                            noruntime : disable EFI runtime services support
                            nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
                            attribute may cause the kernel to reserve the
                            memory range for a memory mapping driver to
                            claim. Specify efi=nosoftreserve to disable this
                            reservation and treat the memory by its base type
                            (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
                            novamap: do not call SetVirtualAddressMap().
                            no_disable_early_pci_dma: Leave the busmaster bit set
                            on all PCI bridges while in the EFI boot stub

            efi_no_storage_paranoia [EFI; X86]
                            Using this parameter you can use more than 50% of
                            your efi variable storage. Use this parameter only if
                            you are really sure that your UEFI does sane gc and
                            fulfills the spec otherwise your board may brick.

            efi_fake_mem=   nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
                            Add arbitrary attribute to specific memory range by
                            updating original EFI memory map.
                            Region of memory which aa attribute is added to is
                            from ss to ss+nn.

                            If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
                            is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
                            attribute is added to range 0x100000000-0x180000000 and
                            0x10a0000000-0x1120000000.

                            If efi_fake_mem=8G@9G:0x40000 is specified, the
                            EFI_MEMORY_SP(0x40000) attribute is added to
                            range 0x240000000-0x43fffffff.

                            Using this parameter you can do debugging of EFI memmap
                            related features. For example, you can do debugging of
                            Address Range Mirroring feature even if your box
                            doesn't support it, or mark specific memory as
                            "soft reserved".

            efivar_ssdt=    [EFI; X86] Name of an EFI variable that contains an SSDT
                            that is to be dynamically loaded by Linux. If there are
                            multiple variables with the same name but with different
                            vendor GUIDs, all of them will be loaded. See
                            Documentation/admin-guide/acpi/ssdt-overlays.rst for details.

            eisa_irq_edge=  [PARISC,HW]
                            See header of drivers/parisc/eisa.c.

            elanfreq=       [X86-32]
                            See comment before function elanfreq_setup() in
                            arch/x86/kernel/cpu/cpufreq/elanfreq.c.

            elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
                            Specifies physical address of start of kernel core
                            image elf header and optionally the size. Generally
                            kexec loader will pass this option to capture kernel.
                            See Documentation/admin-guide/kdump/kdump.rst for details.

            enable_mtrr_cleanup [X86]
                            The kernel tries to adjust MTRR layout from continuous
                            to discrete, to make X server driver able to add WB
                            entry later. This parameter enables that.

            enable_timer_pin_1 [X86]
                            Enable PIN 1 of APIC timer
                            Can be useful to work around chipset bugs
                            (in particular on some ATI chipsets).
                            The kernel tries to set a reasonable default.

            enforcing       [SELINUX] Set initial enforcing status.
                            Format: {"0" | "1"}
                            See security/selinux/Kconfig help text.
                            0 -- permissive (log only, no denials).
                            1 -- enforcing (deny and log).
                            Default value is 0.
                            Value can be changed at runtime via
                            /sys/fs/selinux/enforce.

            erst_disable    [ACPI]
                            Disable Error Record Serialization Table (ERST)
                            support.

            ether=          [HW,NET] Ethernet cards parameters
                            This option is obsoleted by the "netdev=" option, which
                            has equivalent usage. See its documentation for details.

            evm=            [EVM]
                            Format: { "fix" }
                            Permit 'security.evm' to be updated regardless of
                            current integrity status.

            failslab=
            fail_usercopy=
            fail_page_alloc=
            fail_make_request=[KNL]
                            General fault injection mechanism.
                            Format: <interval>,<probability>,<space>,<times>
                            See also Documentation/fault-injection/.

            fb_tunnels=     [NET]
                            Format: { initns | none }
                            See Documentation/admin-guide/sysctl/net.rst for
                            fb_tunnels_only_for_init_ns

            floppy=         [HW]
                            See Documentation/admin-guide/blockdev/floppy.rst.

            force_pal_cache_flush
                            [IA-64] Avoid check_sal_cache_flush which may hang on
                            buggy SAL_CACHE_FLUSH implementations. Using this
                            parameter will force ia64_sal_cache_flush to call
                            ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.

            forcepae        [X86-32]
                            Forcefully enable Physical Address Extension (PAE).
                            Many Pentium M systems disable PAE but may have a
                            functionally usable PAE implementation.
                            Warning: use of this parameter will taint the kernel
                            and may cause unknown problems.

            ftrace=[tracer]
                            [FTRACE] will set and start the specified tracer
                            as early as possible in order to facilitate early
                            boot debugging.

            ftrace_boot_snapshot
                            [FTRACE] On boot up, a snapshot will be taken of the
                            ftrace ring buffer that can be read at:
                            /sys/kernel/tracing/snapshot.
                            This is useful if you need tracing information from kernel
                            boot up that is likely to be overridden by user space
                            start up functionality.

            ftrace_dump_on_oops[=orig_cpu]
                            [FTRACE] will dump the trace buffers on oops.
                            If no parameter is passed, ftrace will dump
                            buffers of all CPUs, but if you pass orig_cpu, it will
                            dump only the buffer of the CPU that triggered the
                            oops.

            ftrace_filter=[function-list]
                            [FTRACE] Limit the functions traced by the function
                            tracer at boot up. function-list is a comma-separated
                            list of functions. This list can be changed at run
                            time by the set_ftrace_filter file in the debugfs
                            tracing directory.

            ftrace_notrace=[function-list]
                            [FTRACE] Do not trace the functions specified in
                            function-list. This list can be changed at run time
                            by the set_ftrace_notrace file in the debugfs
                            tracing directory.

            ftrace_graph_filter=[function-list]
                            [FTRACE] Limit the top level callers functions traced
                            by the function graph tracer at boot up.
                            function-list is a comma-separated list of functions
                            that can be changed at run time by the
                            set_graph_function file in the debugfs tracing directory.

            ftrace_graph_notrace=[function-list]
                            [FTRACE] Do not trace from the functions specified in
                            function-list.  This list is a comma-separated list of
                            functions that can be changed at run time by the
                            set_graph_notrace file in the debugfs tracing directory.

            ftrace_graph_max_depth=<uint>
                            [FTRACE] Used with the function graph tracer. This is
                            the max depth it will trace into a function. This value
                            can be changed at run time by the max_graph_depth file
                            in the tracefs tracing directory. default: 0 (no limit)

            fw_devlink=     [KNL] Create device links between consumer and supplier
                            devices by scanning the firmware to infer the
                            consumer/supplier relationships. This feature is
                            especially useful when drivers are loaded as modules as
                            it ensures proper ordering of tasks like device probing
                            (suppliers first, then consumers), supplier boot state
                            clean up (only after all consumers have probed),
                            suspend/resume & runtime PM (consumers first, then
                            suppliers).
                            Format: { off | permissive | on | rpm }
                            off --  Don't create device links from firmware info.
                            permissive -- Create device links from firmware info
                                    but use it only for ordering boot state clean
                                    up (sync_state() calls).
                            on --   Create device links from firmware info and use it
                                    to enforce probe and suspend/resume ordering.
                            rpm --  Like "on", but also use to order runtime PM.

            fw_devlink.strict=<bool>
                            [KNL] Treat all inferred dependencies as mandatory
                            dependencies. This only applies for fw_devlink=on|rpm.
                            Format: <bool>

            gamecon.map[2|3]=
                            [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
                            support via parallel port (up to 5 devices per port)
                            Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
                            See also Documentation/input/devices/joystick-parport.rst

            gamma=          [HW,DRM]

            gart_fix_e820=  [X86-64] disable the fix e820 for K8 GART
                            Format: off | on
                            default: on

            gcov_persist=   [GCOV] When non-zero (default), profiling data for
                            kernel modules is saved and remains accessible via
                            debugfs, even when the module is unloaded/reloaded.
                            When zero, profiling data is discarded and associated
                            debugfs files are removed at module unload time.

            goldfish        [X86] Enable the goldfish android emulator platform.
                            Don't use this when you are not running on the
                            android emulator

            gpio-mockup.gpio_mockup_ranges
                            [HW] Sets the ranges of gpiochip of for this device.
                            Format: <start1>,<end1>,<start2>,<end2>...
            gpio-mockup.gpio_mockup_named_lines
                            [HW] Let the driver know GPIO lines should be named.

            gpt             [EFI] Forces disk with valid GPT signature but
                            invalid Protective MBR to be treated as GPT. If the
                            primary GPT is corrupted, it enables the backup/alternate
                            GPT to be used instead.

            grcan.enable0=  [HW] Configuration of physical interface 0. Determines
                            the "Enable 0" bit of the configuration register.
                            Format: 0 | 1
                            Default: 0
            grcan.enable1=  [HW] Configuration of physical interface 1. Determines
                            the "Enable 0" bit of the configuration register.
                            Format: 0 | 1
                            Default: 0
            grcan.select=   [HW] Select which physical interface to use.
                            Format: 0 | 1
                            Default: 0
            grcan.txsize=   [HW] Sets the size of the tx buffer.
                            Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
                            Default: 1024
            grcan.rxsize=   [HW] Sets the size of the rx buffer.
                            Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
                            Default: 1024

            hardlockup_all_cpu_backtrace=
                            [KNL] Should the hard-lockup detector generate
                            backtraces on all cpus.
                            Format: 0 | 1

            hashdist=       [KNL,NUMA] Large hashes allocated during boot
                            are distributed across NUMA nodes.  Defaults on
                            for 64-bit NUMA, off otherwise.
                            Format: 0 | 1 (for off | on)

            hcl=            [IA-64] SGI's Hardware Graph compatibility layer

            hd=             [EIDE] (E)IDE hard drive subsystem geometry
                            Format: <cyl>,<head>,<sect>

            hest_disable    [ACPI]
                            Disable Hardware Error Source Table (HEST) support;
                            corresponding firmware-first mode error processing
                            logic will be disabled.

            highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
                            size of <nn>. This works even on boxes that have no
                            highmem otherwise. This also works to reduce highmem
                            size on bigger boxes.

            highres=        [KNL] Enable/disable high resolution timer mode.
                            Valid parameters: "on", "off"
                            Default: "on"

            hlt             [BUGS=ARM,SH]

            hpet=           [X86-32,HPET] option to control HPET usage
                            Format: { enable (default) | disable | force |
                                    verbose }
                            disable: disable HPET and use PIT instead
                            force: allow force enabled of undocumented chips (ICH4,
                                    VIA, nVidia)
                            verbose: show contents of HPET registers during setup

            hpet_mmap=      [X86, HPET_MMAP] Allow userspace to mmap HPET
                            registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.

            hugetlb_cma=    [HW,CMA] The size of a CMA area used for allocation
                            of gigantic hugepages. Or using node format, the size
                            of a CMA area per node can be specified.
                            Format: nn[KMGTPE] or (node format)
                                    <node>:nn[KMGTPE][,<node>:nn[KMGTPE]]

                            Reserve a CMA area of given size and allocate gigantic
                            hugepages using the CMA allocator. If enabled, the
                            boot-time allocation of gigantic hugepages is skipped.

            hugepages=      [HW] Number of HugeTLB pages to allocate at boot.
                            If this follows hugepagesz (below), it specifies
                            the number of pages of hugepagesz to be allocated.
                            If this is the first HugeTLB parameter on the command
                            line, it specifies the number of pages to allocate for
                            the default huge page size. If using node format, the
                            number of pages to allocate per-node can be specified.
                            See also Documentation/admin-guide/mm/hugetlbpage.rst.
                            Format: <integer> or (node format)
                                    <node>:<integer>[,<node>:<integer>]

            hugepagesz=
                            [HW] The size of the HugeTLB pages.  This is used in
                            conjunction with hugepages (above) to allocate huge
                            pages of a specific size at boot.  The pair
                            hugepagesz=X hugepages=Y can be specified once for
                            each supported huge page size. Huge page sizes are
                            architecture dependent.  See also
                            Documentation/admin-guide/mm/hugetlbpage.rst.
                            Format: size[KMG]

            hugetlb_free_vmemmap=
                            [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
                            enabled.
                            Allows heavy hugetlb users to free up some more
                            memory (7 * PAGE_SIZE for each 2MB hugetlb page).
                            Format: { on | off (default) }

                            on:  enable the feature
                            off: disable the feature

                            Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y,
                            the default is on.

                            This is not compatible with memory_hotplug.memmap_on_memory.
                            If both parameters are enabled, hugetlb_free_vmemmap takes
                            precedence over memory_hotplug.memmap_on_memory.

            hung_task_panic=
                            [KNL] Should the hung task detector generate panics.
                            Format: 0 | 1

                            A value of 1 instructs the kernel to panic when a
                            hung task is detected. The default value is controlled
                            by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
                            option. The value selected by this boot parameter can
                            be changed later by the kernel.hung_task_panic sysctl.

            hvc_iucv=       [S390]  Number of z/VM IUCV hypervisor console (HVC)
                                    terminal devices. Valid values: 0..8
            hvc_iucv_allow= [S390]  Comma-separated list of z/VM user IDs.
                                    If specified, z/VM IUCV HVC accepts connections
                                    from listed z/VM user IDs only.

            hv_nopvspin     [X86,HYPER_V] Disables the paravirt spinlock optimizations
                                          which allow the hypervisor to 'idle' the
                                          guest on lock contention.

            keep_bootcon    [KNL]
                            Do not unregister boot console at start. This is only
                            useful for debugging when something happens in the window
                            between unregistering the boot console and initializing
                            the real console.

            i2c_bus=        [HW]    Override the default board specific I2C bus speed
                                    or register an additional I2C bus that is not
                                    registered from board initialization code.
                                    Format:
                                    <bus_id>,<clkrate>

            i8042.debug     [HW] Toggle i8042 debug mode
            i8042.unmask_kbd_data
                            [HW] Enable printing of interrupt data from the KBD port
                                 (disabled by default, and as a pre-condition
                                 requires that i8042.debug=1 be enabled)
            i8042.direct    [HW] Put keyboard port into non-translated mode
            i8042.dumbkbd   [HW] Pretend that controller can only read data from
                                 keyboard and cannot control its state
                                 (Don't attempt to blink the leds)
            i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
            i8042.nokbd     [HW] Don't check/create keyboard port
            i8042.noloop    [HW] Disable the AUX Loopback command while probing
                                 for the AUX port
            i8042.nomux     [HW] Don't check presence of an active multiplexing
                                 controller
            i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
                                 controllers
            i8042.notimeout [HW] Ignore timeout condition signalled by controller
            i8042.reset     [HW] Reset the controller during init, cleanup and
                                 suspend-to-ram transitions, only during s2r
                                 transitions, or never reset
                            Format: { 1 | Y | y | 0 | N | n }
                            1, Y, y: always reset controller
                            0, N, n: don't ever reset controller
                            Default: only on s2r transitions on x86; most other
                            architectures force reset to be always executed
            i8042.unlock    [HW] Unlock (ignore) the keylock
            i8042.kbdreset  [HW] Reset device connected to KBD port
            i8042.probe_defer
                            [HW] Allow deferred probing upon i8042 probe errors

            i810=           [HW,DRM]

            i915.invert_brightness=
                            [DRM] Invert the sense of the variable that is used to
                            set the brightness of the panel backlight. Normally a
                            brightness value of 0 indicates backlight switched off,
                            and the maximum of the brightness value sets the backlight
                            to maximum brightness. If this parameter is set to 0
                            (default) and the machine requires it, or this parameter
                            is set to 1, a brightness value of 0 sets the backlight
                            to maximum brightness, and the maximum of the brightness
                            value switches the backlight off.
                            -1 -- never invert brightness
                             0 -- machine default
                             1 -- force brightness inversion

            icn=            [HW,ISDN]
                            Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]

            ide-core.nodma= [HW] (E)IDE subsystem
                            Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
                            .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
                            .cdrom .chs .ignore_cable are additional options
                            See Documentation/ide/ide.rst.

            ide-generic.probe-mask= [HW] (E)IDE subsystem
                            Format: <int>
                            Probe mask for legacy ISA IDE ports.  Depending on
                            platform up to 6 ports are supported, enabled by
                            setting corresponding bits in the mask to 1.  The
                            default value is 0x0, which has a special meaning.
                            On systems that have PCI, it triggers scanning the
                            PCI bus for the first and the second port, which
                            are then probed.  On systems without PCI the value
                            of 0x0 enables probing the two first ports as if it
                            was 0x3.

            ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
                            Claim all unknown PCI IDE storage controllers.

            idle=           [X86]
                            Format: idle=poll, idle=halt, idle=nomwait
                            Poll forces a polling idle loop that can slightly
                            improve the performance of waking up a idle CPU, but
                            will use a lot of power and make the system run hot.
                            Not recommended.
                            idle=halt: Halt is forced to be used for CPU idle.
                            In such case C2/C3 won't be used again.
                            idle=nomwait: Disable mwait for CPU C-states

            idxd.sva=       [HW]
                            Format: <bool>
                            Allow force disabling of Shared Virtual Memory (SVA)
                            support for the idxd driver. By default it is set to
                            true (1).

            idxd.tc_override= [HW]
                            Format: <bool>
                            Allow override of default traffic class configuration
                            for the device. By default it is set to false (0).

            ieee754=        [MIPS] Select IEEE Std 754 conformance mode
                            Format: { strict | legacy | 2008 | relaxed }
                            Default: strict

                            Choose which programs will be accepted for execution
                            based on the IEEE 754 NaN encoding(s) supported by
                            the FPU and the NaN encoding requested with the value
                            of an ELF file header flag individually set by each
                            binary.  Hardware implementations are permitted to
                            support either or both of the legacy and the 2008 NaN
                            encoding mode.

                            Available settings are as follows:
                            strict  accept binaries that request a NaN encoding
                                    supported by the FPU
                            legacy  only accept legacy-NaN binaries, if supported
                                    by the FPU
                            2008    only accept 2008-NaN binaries, if supported
                                    by the FPU
                            relaxed accept any binaries regardless of whether
                                    supported by the FPU

                            The FPU emulator is always able to support both NaN
                            encodings, so if no FPU hardware is present or it has
                            been disabled with 'nofpu', then the settings of
                            'legacy' and '2008' strap the emulator accordingly,
                            'relaxed' straps the emulator for both legacy-NaN and
                            2008-NaN, whereas 'strict' enables legacy-NaN only on
                            legacy processors and both NaN encodings on MIPS32 or
                            MIPS64 CPUs.

                            The setting for ABS.fmt/NEG.fmt instruction execution
                            mode generally follows that for the NaN encoding,
                            except where unsupported by hardware.

            ignore_loglevel [KNL]
                            Ignore loglevel setting - this will print /all/
                            kernel messages to the console. Useful for debugging.
                            We also add it as printk module parameter, so users
                            could change it dynamically, usually by
                            /sys/module/printk/parameters/ignore_loglevel.

            ignore_rlimit_data
                            Ignore RLIMIT_DATA setting for data mappings,
                            print warning at first misuse.  Can be changed via
                            /sys/module/kernel/parameters/ignore_rlimit_data.

            ihash_entries=  [KNL]
                            Set number of hash buckets for inode cache.

            ima_appraise=   [IMA] appraise integrity measurements
                            Format: { "off" | "enforce" | "fix" | "log" }
                            default: "enforce"

            ima_appraise_tcb [IMA] Deprecated.  Use ima_policy= instead.
                            The builtin appraise policy appraises all files
                            owned by uid=0.

            ima_canonical_fmt [IMA]
                            Use the canonical format for the binary runtime
                            measurements, instead of host native format.

            ima_hash=       [IMA]
                            Format: { md5 | sha1 | rmd160 | sha256 | sha384
                                       | sha512 | ... }
                            default: "sha1"

                            The list of supported hash algorithms is defined
                            in crypto/hash_info.h.

            ima_policy=     [IMA]
                            The builtin policies to load during IMA setup.
                            Format: "tcb | appraise_tcb | secure_boot |
                                     fail_securely | critical_data"

                            The "tcb" policy measures all programs exec'd, files
                            mmap'd for exec, and all files opened with the read
                            mode bit set by either the effective uid (euid=0) or
                            uid=0.

                            The "appraise_tcb" policy appraises the integrity of
                            all files owned by root.

                            The "secure_boot" policy appraises the integrity
                            of files (eg. kexec kernel image, kernel modules,
                            firmware, policy, etc) based on file signatures.

                            The "fail_securely" policy forces file signature
                            verification failure also on privileged mounted
                            filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
                            flag.

                            The "critical_data" policy measures kernel integrity
                            critical data.

            ima_tcb         [IMA] Deprecated.  Use ima_policy= instead.
                            Load a policy which meets the needs of the Trusted
                            Computing Base.  This means IMA will measure all
                            programs exec'd, files mmap'd for exec, and all files
                            opened for read by uid=0.

            ima_template=   [IMA]
                            Select one of defined IMA measurements template formats.
                            Formats: { "ima" | "ima-ng" | "ima-sig" }
                            Default: "ima-ng"

            ima_template_fmt=
                            [IMA] Define a custom template format.
                            Format: { "field1|...|fieldN" }

            ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
                            Format: <min_file_size>
                            Set the minimal file size for using asynchronous hash.
                            If left unspecified, ahash usage is disabled.

                            ahash performance varies for different data sizes on
                            different crypto accelerators. This option can be used
                            to achieve the best performance for a particular HW.

            ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
                            Format: <bufsize>
                            Set hashing buffer size. Default: 4k.

                            ahash performance varies for different chunk sizes on
                            different crypto accelerators. This option can be used
                            to achieve best performance for particular HW.

            init=           [KNL]
                            Format: <full_path>
                            Run specified binary instead of /sbin/init as init
                            process.

            initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
                            for working out where the kernel is dying during
                            startup.

            initcall_blacklist=  [KNL] Do not execute a comma-separated list of
                            initcall functions.  Useful for debugging built-in
                            modules and initcalls.

            initramfs_async= [KNL]
                            Format: <bool>
                            Default: 1
                            This parameter controls whether the initramfs
                            image is unpacked asynchronously, concurrently
                            with devices being probed and
                            initialized. This should normally just work,
                            but as a debugging aid, one can get the
                            historical behaviour of the initramfs
                            unpacking being completed before device_ and
                            late_ initcalls.

            initrd=         [BOOT] Specify the location of the initial ramdisk

            initrdmem=      [KNL] Specify a physical address and size from which to
                            load the initrd. If an initrd is compiled in or
                            specified in the bootparams, it takes priority over this
                            setting.
                            Format: ss[KMG],nn[KMG]
                            Default is 0, 0

            init_on_alloc=  [MM] Fill newly allocated pages and heap objects with
                            zeroes.
                            Format: 0 | 1
                            Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.

            init_on_free=   [MM] Fill freed pages and heap objects with zeroes.
                            Format: 0 | 1
                            Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.

            init_pkru=      [X86] Specify the default memory protection keys rights
                            register contents for all processes.  0x55555554 by
                            default (disallow access to all but pkey 0).  Can
                            override in debugfs after boot.

            inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
                            Format: <irq>

            int_pln_enable  [X86] Enable power limit notification interrupt

            integrity_audit=[IMA]
                            Format: { "0" | "1" }
                            0 -- basic integrity auditing messages. (Default)
                            1 -- additional integrity auditing messages.

            intel_iommu=    [DMAR] Intel IOMMU driver (DMAR) option
                    on
                            Enable intel iommu driver.
                    off
                            Disable intel iommu driver.
                    igfx_off [Default Off]
                            By default, gfx is mapped as normal device. If a gfx
                            device has a dedicated DMAR unit, the DMAR unit is
                            bypassed by not enabling DMAR with this option. In
                            this case, gfx device will use physical address for
                            DMA.
                    strict [Default Off]
                            Deprecated, equivalent to iommu.strict=1.
                    sp_off [Default Off]
                            By default, super page will be supported if Intel IOMMU
                            has the capability. With this option, super page will
                            not be supported.
                    sm_on
                            Enable the Intel IOMMU scalable mode if the hardware
                            advertises that it has support for the scalable mode
                            translation.
                    sm_off
                            Disallow use of the Intel IOMMU scalable mode.
                    tboot_noforce [Default Off]
                            Do not force the Intel IOMMU enabled under tboot.
                            By default, tboot will force Intel IOMMU on, which
                            could harm performance of some high-throughput
                            devices like 40GBit network cards, even if identity
                            mapping is enabled.
                            Note that using this option lowers the security
                            provided by tboot because it makes the system
                            vulnerable to DMA attacks.

            intel_idle.max_cstate=  [KNL,HW,ACPI,X86]
                            0       disables intel_idle and fall back on acpi_idle.
                            1 to 9  specify maximum depth of C-state.

            intel_pstate=   [X86]
                            disable
                              Do not enable intel_pstate as the default
                              scaling driver for the supported processors
                            passive
                              Use intel_pstate as a scaling driver, but configure it
                              to work with generic cpufreq governors (instead of
                              enabling its internal governor).  This mode cannot be
                              used along with the hardware-managed P-states (HWP)
                              feature.
                            force
                              Enable intel_pstate on systems that prohibit it by default
                              in favor of acpi-cpufreq. Forcing the intel_pstate driver
                              instead of acpi-cpufreq may disable platform features, such
                              as thermal controls and power capping, that rely on ACPI
                              P-States information being indicated to OSPM and therefore
                              should be used with caution. This option does not work with
                              processors that aren't supported by the intel_pstate driver
                              or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
                            no_hwp
                              Do not enable hardware P state control (HWP)
                              if available.
                            hwp_only
                              Only load intel_pstate on systems which support
                              hardware P state control (HWP) if available.
                            support_acpi_ppc
                              Enforce ACPI _PPC performance limits. If the Fixed ACPI
                              Description Table, specifies preferred power management
                              profile as "Enterprise Server" or "Performance Server",
                              then this feature is turned on by default.
                            per_cpu_perf_limits
                              Allow per-logical-CPU P-State performance control limits using
                              cpufreq sysfs interface

            intremap=       [X86-64, Intel-IOMMU]
                            on      enable Interrupt Remapping (default)
                            off     disable Interrupt Remapping
                            nosid   disable Source ID checking
                            no_x2apic_optout
                                    BIOS x2APIC opt-out request will be ignored
                            nopost  disable Interrupt Posting

            iomem=          Disable strict checking of access to MMIO memory
                    strict  regions from userspace.
                    relaxed

            iommu=          [X86]
                    off
                    force
                    noforce
                    biomerge
                    panic
                    nopanic
                    merge
                    nomerge
                    soft
                    pt              [X86]
                    nopt            [X86]
                    nobypass        [PPC/POWERNV]
                            Disable IOMMU bypass, using IOMMU for PCI devices.

            iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices.
                            Format: { "0" | "1" }
                            0 - Try to allocate a 32-bit DMA address first, before
                              falling back to the full range if needed.
                            1 - Allocate directly from the full usable range,
                              forcing Dual Address Cycle for PCI cards supporting
                              greater than 32-bit addressing.

            iommu.strict=   [ARM64, X86] Configure TLB invalidation behaviour
                            Format: { "0" | "1" }
                            0 - Lazy mode.
                              Request that DMA unmap operations use deferred
                              invalidation of hardware TLBs, for increased
                              throughput at the cost of reduced device isolation.
                              Will fall back to strict mode if not supported by
                              the relevant IOMMU driver.
                            1 - Strict mode.
                              DMA unmap operations invalidate IOMMU hardware TLBs
                              synchronously.
                            unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
                            Note: on x86, strict mode specified via one of the
                            legacy driver-specific options takes precedence.

            iommu.passthrough=
                            [ARM64, X86] Configure DMA to bypass the IOMMU by default.
                            Format: { "0" | "1" }
                            0 - Use IOMMU translation for DMA.
                            1 - Bypass the IOMMU for DMA.
                            unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.

            io7=            [HW] IO7 for Marvel-based Alpha systems
                            See comment before marvel_specify_io7 in
                            arch/alpha/kernel/core_marvel.c.

            io_delay=       [X86] I/O delay method
                    0x80
                            Standard port 0x80 based delay
                    0xed
                            Alternate port 0xed based delay (needed on some systems)
                    udelay
                            Simple two microseconds delay
                    none
                            No delay

            ip=             [IP_PNP]
                            See Documentation/admin-guide/nfs/nfsroot.rst.

            ipcmni_extend   [KNL] Extend the maximum number of unique System V
                            IPC identifiers from 32,768 to 16,777,216.

            irqaffinity=    [SMP] Set the default irq affinity mask
                            The argument is a cpu list, as described above.

            irqchip.gicv2_force_probe=
                            [ARM, ARM64]
                            Format: <bool>
                            Force the kernel to look for the second 4kB page
                            of a GICv2 controller even if the memory range
                            exposed by the device tree is too small.

            irqchip.gicv3_nolpi=
                            [ARM, ARM64]
                            Force the kernel to ignore the availability of
                            LPIs (and by consequence ITSs). Intended for system
                            that use the kernel as a bootloader, and thus want
                            to let secondary kernels in charge of setting up
                            LPIs.

            irqchip.gicv3_pseudo_nmi= [ARM64]
                            Enables support for pseudo-NMIs in the kernel. This
                            requires the kernel to be built with
                            CONFIG_ARM64_PSEUDO_NMI.

            irqfixup        [HW]
                            When an interrupt is not handled search all handlers
                            for it. Intended to get systems with badly broken
                            firmware running.

            irqpoll         [HW]
                            When an interrupt is not handled search all handlers
                            for it. Also check all handlers each timer
                            interrupt. Intended to get systems with badly broken
                            firmware running.

            isapnp=         [ISAPNP]
                            Format: <RDP>,<reset>,<pci_scan>,<verbosity>

            isolcpus=       [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
                            [Deprecated - use cpusets instead]
                            Format: [flag-list,]<cpu-list>

                            Specify one or more CPUs to isolate from disturbances
                            specified in the flag list (default: domain):

                            nohz
                              Disable the tick when a single task runs.

                              A residual 1Hz tick is offloaded to workqueues, which you
                              need to affine to housekeeping through the global
                              workqueue's affinity configured via the
                              /sys/devices/virtual/workqueue/cpumask sysfs file, or
                              by using the 'domain' flag described below.

                              NOTE: by default the global workqueue runs on all CPUs,
                              so to protect individual CPUs the 'cpumask' file has to
                              be configured manually after bootup.

                            domain
                              Isolate from the general SMP balancing and scheduling
                              algorithms. Note that performing domain isolation this way
                              is irreversible: it's not possible to bring back a CPU to
                              the domains once isolated through isolcpus. It's strongly
                              advised to use cpusets instead to disable scheduler load
                              balancing through the "cpuset.sched_load_balance" file.
                              It offers a much more flexible interface where CPUs can
                              move in and out of an isolated set anytime.

                              You can move a process onto or off an "isolated" CPU via
                              the CPU affinity syscalls or cpuset.
                              <cpu number> begins at 0 and the maximum value is
                              "number of CPUs in system - 1".

                            managed_irq

                              Isolate from being targeted by managed interrupts
                              which have an interrupt mask containing isolated
                              CPUs. The affinity of managed interrupts is
                              handled by the kernel and cannot be changed via
                              the /proc/irq/* interfaces.

                              This isolation is best effort and only effective
                              if the automatically assigned interrupt mask of a
                              device queue contains isolated and housekeeping
                              CPUs. If housekeeping CPUs are online then such
                              interrupts are directed to the housekeeping CPU
                              so that IO submitted on the housekeeping CPU
                              cannot disturb the isolated CPU.

                              If a queue's affinity mask contains only isolated
                              CPUs then this parameter has no effect on the
                              interrupt routing decision, though interrupts are
                              only delivered when tasks running on those
                              isolated CPUs submit IO. IO submitted on
                              housekeeping CPUs has no influence on those
                              queues.

                            The format of <cpu-list> is described above.

            iucv=           [HW,NET]

            ivrs_ioapic     [HW,X86-64]
                            Provide an override to the IOAPIC-ID<->DEVICE-ID
                            mapping provided in the IVRS ACPI table. For
                            example, to map IOAPIC-ID decimal 10 to
                            PCI device 00:14.0 write the parameter as:
                                    ivrs_ioapic[10]=00:14.0

            ivrs_hpet       [HW,X86-64]
                            Provide an override to the HPET-ID<->DEVICE-ID
                            mapping provided in the IVRS ACPI table. For
                            example, to map HPET-ID decimal 0 to
                            PCI device 00:14.0 write the parameter as:
                                    ivrs_hpet[0]=00:14.0

            ivrs_acpihid    [HW,X86-64]
                            Provide an override to the ACPI-HID:UID<->DEVICE-ID
                            mapping provided in the IVRS ACPI table. For
                            example, to map UART-HID:UID AMD0020:0 to
                            PCI device 00:14.5 write the parameter as:
                                    ivrs_acpihid[00:14.5]=AMD0020:0

            js=             [HW,JOY] Analog joystick
                            See Documentation/input/joydev/joystick.rst.

            nokaslr         [KNL]
                            When CONFIG_RANDOMIZE_BASE is set, this disables
                            kernel and module base offset ASLR (Address Space
                            Layout Randomization).

            kasan_multi_shot
                            [KNL] Enforce KASAN (Kernel Address Sanitizer) to print
                            report on every invalid memory access. Without this
                            parameter KASAN will print report only for the first
                            invalid access.

            keepinitrd      [HW,ARM]

            kernelcore=     [KNL,X86,IA-64,PPC]
                            Format: nn[KMGTPE] | nn% | "mirror"
                            This parameter specifies the amount of memory usable by
                            the kernel for non-movable allocations.  The requested
                            amount is spread evenly throughout all nodes in the
                            system as ZONE_NORMAL.  The remaining memory is used for
                            movable memory in its own zone, ZONE_MOVABLE.  In the
                            event, a node is too small to have both ZONE_NORMAL and
                            ZONE_MOVABLE, kernelcore memory will take priority and
                            other nodes will have a larger ZONE_MOVABLE.

                            ZONE_MOVABLE is used for the allocation of pages that
                            may be reclaimed or moved by the page migration
                            subsystem.  Note that allocations like PTEs-from-HighMem
                            still use the HighMem zone if it exists, and the Normal
                            zone if it does not.

                            It is possible to specify the exact amount of memory in
                            the form of "nn[KMGTPE]", a percentage of total system
                            memory in the form of "nn%", or "mirror".  If "mirror"
                            option is specified, mirrored (reliable) memory is used
                            for non-movable allocations and remaining memory is used
                            for Movable pages.  "nn[KMGTPE]", "nn%", and "mirror"
                            are exclusive, so you cannot specify multiple forms.

            kgdbdbgp=       [KGDB,HW] kgdb over EHCI usb debug port.
                            Format: <Controller#>[,poll interval]
                            The controller # is the number of the ehci usb debug
                            port as it is probed via PCI.  The poll interval is
                            optional and is the number seconds in between
                            each poll cycle to the debug port in case you need
                            the functionality for interrupting the kernel with
                            gdb or control-c on the dbgp connection.  When
                            not using this parameter you use sysrq-g to break into
                            the kernel debugger.

            kgdboc=         [KGDB,HW] kgdb over consoles.
                            Requires a tty driver that supports console polling,
                            or a supported polling keyboard driver (non-usb).
                             Serial only format: <serial_device>[,baud]
                             keyboard only format: kbd
                             keyboard and serial format: kbd,<serial_device>[,baud]
                            Optional Kernel mode setting:
                             kms, kbd format: kms,kbd
                             kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]

            kgdboc_earlycon=        [KGDB,HW]
                            If the boot console provides the ability to read
                            characters and can work in polling mode, you can use
                            this parameter to tell kgdb to use it as a backend
                            until the normal console is registered. Intended to
                            be used together with the kgdboc parameter which
                            specifies the normal console to transition to.

                            The name of the early console should be specified
                            as the value of this parameter. Note that the name of
                            the early console might be different than the tty
                            name passed to kgdboc. It's OK to leave the value
                            blank and the first boot console that implements
                            read() will be picked.

            kgdbwait        [KGDB] Stop kernel execution and enter the
                            kernel debugger at the earliest opportunity.

            kmac=           [MIPS] Korina ethernet MAC address.
                            Configure the RouterBoard 532 series on-chip
                            Ethernet adapter MAC address.

            kmemleak=       [KNL] Boot-time kmemleak enable/disable
                            Valid arguments: on, off
                            Default: on
                            Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
                            the default is off.

            kprobe_event=[probe-list]
                            [FTRACE] Add kprobe events and enable at boot time.
                            The probe-list is a semicolon delimited list of probe
                            definitions. Each definition is same as kprobe_events
                            interface, but the parameters are comma delimited.
                            For example, to add a kprobe event on vfs_read with
                            arg1 and arg2, add to the command line;

                                  kprobe_event=p,vfs_read,$arg1,$arg2

                            See also Documentation/trace/kprobetrace.rst "Kernel
                            Boot Parameter" section.

            kpti=           [ARM64] Control page table isolation of user
                            and kernel address spaces.
                            Default: enabled on cores which need mitigation.
                            0: force disabled
                            1: force enabled

            kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
                            Default is 0 (don't ignore, but inject #GP)

            kvm.eager_page_split=
                            [KVM,X86] Controls whether or not KVM will try to
                            proactively split all huge pages during dirty logging.
                            Eager page splitting reduces interruptions to vCPU
                            execution by eliminating the write-protection faults
                            and MMU lock contention that would otherwise be
                            required to split huge pages lazily.

                            VM workloads that rarely perform writes or that write
                            only to a small region of VM memory may benefit from
                            disabling eager page splitting to allow huge pages to
                            still be used for reads.

                            The behavior of eager page splitting depends on whether
                            KVM_DIRTY_LOG_INITIALLY_SET is enabled or disabled. If
                            disabled, all huge pages in a memslot will be eagerly
                            split when dirty logging is enabled on that memslot. If
                            enabled, eager page splitting will be performed during
                            the KVM_CLEAR_DIRTY ioctl, and only for the pages being
                            cleared.

                            Eager page splitting currently only supports splitting
                            huge pages mapped by the TDP MMU.

                            Default is Y (on).

            kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface.
                                       Default is false (don't support).

            kvm.nx_huge_pages=
                            [KVM] Controls the software workaround for the
                            X86_BUG_ITLB_MULTIHIT bug.
                            force   : Always deploy workaround.
                            off     : Never deploy workaround.
                            auto    : Deploy workaround based on the presence of
                                      X86_BUG_ITLB_MULTIHIT.

                            Default is 'auto'.

                            If the software workaround is enabled for the host,
                            guests do need not to enable it for nested guests.

            kvm.nx_huge_pages_recovery_ratio=
                            [KVM] Controls how many 4KiB pages are periodically zapped
                            back to huge pages.  0 disables the recovery, otherwise if
                            the value is N KVM will zap 1/Nth of the 4KiB pages every
                            period (see below).  The default is 60.

            kvm.nx_huge_pages_recovery_period_ms=
                            [KVM] Controls the time period at which KVM zaps 4KiB pages
                            back to huge pages. If the value is a non-zero N, KVM will
                            zap a portion (see ratio above) of the pages every N msecs.
                            If the value is 0 (the default), KVM will pick a period based
                            on the ratio, such that a page is zapped after 1 hour on average.

            kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
                            Default is 1 (enabled)

            kvm-amd.npt=    [KVM,AMD] Disable nested paging (virtualized MMU)
                            for all guests.
                            Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.

            kvm-arm.mode=
                            [KVM,ARM] Select one of KVM/arm64's modes of operation.

                            none: Forcefully disable KVM.

                            nvhe: Standard nVHE-based mode, without support for
                                  protected guests.

                            protected: nVHE-based mode with support for guests whose
                                       state is kept private from the host.
                                       Not valid if the kernel is running in EL2.

                            Defaults to VHE/nVHE based on hardware support. Setting
                            mode to "protected" will disable kexec and hibernation
                            for the host.

            kvm-arm.vgic_v3_group0_trap=
                            [KVM,ARM] Trap guest accesses to GICv3 group-0
                            system registers

            kvm-arm.vgic_v3_group1_trap=
                            [KVM,ARM] Trap guest accesses to GICv3 group-1
                            system registers

            kvm-arm.vgic_v3_common_trap=
                            [KVM,ARM] Trap guest accesses to GICv3 common
                            system registers

            kvm-arm.vgic_v4_enable=
                            [KVM,ARM] Allow use of GICv4 for direct injection of
                            LPIs.

            kvm_cma_resv_ratio=n [PPC]
                            Reserves given percentage from system memory area for
                            contiguous memory allocation for KVM hash pagetable
                            allocation.
                            By default it reserves 5% of total system memory.
                            Format: <integer>
                            Default: 5

            kvm-intel.ept=  [KVM,Intel] Disable extended page tables
                            (virtualized MMU) support on capable Intel chips.
                            Default is 1 (enabled)

            kvm-intel.emulate_invalid_guest_state=
                            [KVM,Intel] Disable emulation of invalid guest state.
                            Ignored if kvm-intel.enable_unrestricted_guest=1, as
                            guest state is never invalid for unrestricted guests.
                            This param doesn't apply to nested guests (L2), as KVM
                            never emulates invalid L2 guest state.
                            Default is 1 (enabled)

            kvm-intel.flexpriority=
                            [KVM,Intel] Disable FlexPriority feature (TPR shadow).
                            Default is 1 (enabled)

            kvm-intel.nested=
                            [KVM,Intel] Enable VMX nesting (nVMX).
                            Default is 0 (disabled)

            kvm-intel.unrestricted_guest=
                            [KVM,Intel] Disable unrestricted guest feature
                            (virtualized real and unpaged mode) on capable
                            Intel chips. Default is 1 (enabled)

            kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
                            CVE-2018-3620.

                            Valid arguments: never, cond, always

                            always: L1D cache flush on every VMENTER.
                            cond:   Flush L1D on VMENTER only when the code between
                                    VMEXIT and VMENTER can leak host memory.
                            never:  Disables the mitigation

                            Default is cond (do L1 cache flush in specific instances)

            kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
                            feature (tagged TLBs) on capable Intel chips.
                            Default is 1 (enabled)

            l1d_flush=      [X86,INTEL]
                            Control mitigation for L1D based snooping vulnerability.

                            Certain CPUs are vulnerable to an exploit against CPU
                            internal buffers which can forward information to a
                            disclosure gadget under certain conditions.

                            In vulnerable processors, the speculatively
                            forwarded data can be used in a cache side channel
                            attack, to access data to which the attacker does
                            not have direct access.

                            This parameter controls the mitigation. The
                            options are:

                            on         - enable the interface for the mitigation

            l1tf=           [X86] Control mitigation of the L1TF vulnerability on
                                  affected CPUs

                            The kernel PTE inversion protection is unconditionally
                            enabled and cannot be disabled.

                            full
                                    Provides all available mitigations for the
                                    L1TF vulnerability. Disables SMT and
                                    enables all mitigations in the
                                    hypervisors, i.e. unconditional L1D flush.

                                    SMT control and L1D flush control via the
                                    sysfs interface is still possible after
                                    boot.  Hypervisors will issue a warning
                                    when the first VM is started in a
                                    potentially insecure configuration,
                                    i.e. SMT enabled or L1D flush disabled.

                            full,force
                                    Same as 'full', but disables SMT and L1D
                                    flush runtime control. Implies the
                                    'nosmt=force' command line option.
                                    (i.e. sysfs control of SMT is disabled.)

                            flush
                                    Leaves SMT enabled and enables the default
                                    hypervisor mitigation, i.e. conditional
                                    L1D flush.

                                    SMT control and L1D flush control via the
                                    sysfs interface is still possible after
                                    boot.  Hypervisors will issue a warning
                                    when the first VM is started in a
                                    potentially insecure configuration,
                                    i.e. SMT enabled or L1D flush disabled.

                            flush,nosmt

                                    Disables SMT and enables the default
                                    hypervisor mitigation.

                                    SMT control and L1D flush control via the
                                    sysfs interface is still possible after
                                    boot.  Hypervisors will issue a warning
                                    when the first VM is started in a
                                    potentially insecure configuration,
                                    i.e. SMT enabled or L1D flush disabled.

                            flush,nowarn
                                    Same as 'flush', but hypervisors will not
                                    warn when a VM is started in a potentially
                                    insecure configuration.

                            off
                                    Disables hypervisor mitigations and doesn't
                                    emit any warnings.
                                    It also drops the swap size and available
                                    RAM limit restriction on both hypervisor and
                                    bare metal.

                            Default is 'flush'.

                            For details see: Documentation/admin-guide/hw-vuln/l1tf.rst

            l2cr=           [PPC]

            l3cr=           [PPC]

            lapic           [X86-32,APIC] Enable the local APIC even if BIOS
                            disabled it.

            lapic=          [X86,APIC] Do not use TSC deadline
                            value for LAPIC timer one-shot implementation. Default
                            back to the programmable timer unit in the LAPIC.
                            Format: notscdeadline

            lapic_timer_c2_ok       [X86,APIC] trust the local apic timer
                            in C2 power state.

            libata.dma=     [LIBATA] DMA control
                            libata.dma=0      Disable all PATA and SATA DMA
                            libata.dma=1      PATA and SATA Disk DMA only
                            libata.dma=2      ATAPI (CDROM) DMA only
                            libata.dma=4      Compact Flash DMA only
                            Combinations also work, so libata.dma=3 enables DMA
                            for disks and CDROMs, but not CFs.

            libata.ignore_hpa=      [LIBATA] Ignore HPA limit
                            libata.ignore_hpa=0       keep BIOS limits (default)
                            libata.ignore_hpa=1       ignore limits, using full disk

            libata.noacpi   [LIBATA] Disables use of ACPI in libata suspend/resume
                            when set.
                            Format: <int>

            libata.force=   [LIBATA] Force configurations.  The format is comma-
                            separated list of "[ID:]VAL" where ID is
                            PORT[.DEVICE].  PORT and DEVICE are decimal numbers
                            matching port, link or device.  Basically, it matches
                            the ATA ID string printed on console by libata.  If
                            the whole ID part is omitted, the last PORT and DEVICE
                            values are used.  If ID hasn't been specified yet, the
                            configuration applies to all ports, links and devices.

                            If only DEVICE is omitted, the parameter applies to
                            the port and all links and devices behind it.  DEVICE
                            number of 0 either selects the first device or the
                            first fan-out link behind PMP device.  It does not
                            select the host link.  DEVICE number of 15 selects the
                            host link and device attached to it.

                            The VAL specifies the configuration to force.  As long
                            as there's no ambiguity shortcut notation is allowed.
                            For example, both 1.5 and 1.5G would work for 1.5Gbps.
                            The following configurations can be forced.

                            * Cable type: 40c, 80c, short40c, unk, ign or sata.
                              Any ID with matching PORT is used.

                            * SATA link speed limit: 1.5Gbps or 3.0Gbps.

                            * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
                              udma[/][16,25,33,44,66,100,133] notation is also
                              allowed.

                            * [no]ncq: Turn on or off NCQ.

                            * [no]ncqtrim: Turn off queued DSM TRIM.

                            * nohrst, nosrst, norst: suppress hard, soft
                              and both resets.

                            * rstonce: only attempt one reset during
                              hot-unplug link recovery

                            * dump_id: dump IDENTIFY data.

                            * atapi_dmadir: Enable ATAPI DMADIR bridge support

                            * disable: Disable this device.

                            If there are multiple matching configurations changing
                            the same attribute, the last one is used.

            memblock=debug  [KNL] Enable memblock debug messages.

            load_ramdisk=   [RAM] [Deprecated]

            lockd.nlm_grace_period=P  [NFS] Assign grace period.
                            Format: <integer>

            lockd.nlm_tcpport=N     [NFS] Assign TCP port.
                            Format: <integer>

            lockd.nlm_timeout=T     [NFS] Assign timeout value.
                            Format: <integer>

            lockd.nlm_udpport=M     [NFS] Assign UDP port.
                            Format: <integer>

            lockdown=       [SECURITY]
                            { integrity | confidentiality }
                            Enable the kernel lockdown feature. If set to
                            integrity, kernel features that allow userland to
                            modify the running kernel are disabled. If set to
                            confidentiality, kernel features that allow userland
                            to extract confidential information from the kernel
                            are also disabled.

            locktorture.nreaders_stress= [KNL]
                            Set the number of locking read-acquisition kthreads.
                            Defaults to being automatically set based on the
                            number of online CPUs.

            locktorture.nwriters_stress= [KNL]
                            Set the number of locking write-acquisition kthreads.

            locktorture.onoff_holdoff= [KNL]
                            Set time (s) after boot for CPU-hotplug testing.

            locktorture.onoff_interval= [KNL]
                            Set time (s) between CPU-hotplug operations, or
                            zero to disable CPU-hotplug testing.

            locktorture.shuffle_interval= [KNL]
                            Set task-shuffle interval (jiffies).  Shuffling
                            tasks allows some CPUs to go into dyntick-idle
                            mode during the locktorture test.

            locktorture.shutdown_secs= [KNL]
                            Set time (s) after boot system shutdown.  This
                            is useful for hands-off automated testing.

            locktorture.stat_interval= [KNL]
                            Time (s) between statistics printk()s.

            locktorture.stutter= [KNL]
                            Time (s) to stutter testing, for example,
                            specifying five seconds causes the test to run for
                            five seconds, wait for five seconds, and so on.
                            This tests the locking primitive's ability to
                            transition abruptly to and from idle.

            locktorture.torture_type= [KNL]
                            Specify the locking implementation to test.

            locktorture.verbose= [KNL]
                            Enable additional printk() statements.

            logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
                            Format: <irq>

            loglevel=       All Kernel Messages with a loglevel smaller than the
                            console loglevel will be printed to the console. It can
                            also be changed with klogd or other programs. The
                            loglevels are defined as follows:

                            0 (KERN_EMERG)          system is unusable
                            1 (KERN_ALERT)          action must be taken immediately
                            2 (KERN_CRIT)           critical conditions
                            3 (KERN_ERR)            error conditions
                            4 (KERN_WARNING)        warning conditions
                            5 (KERN_NOTICE)         normal but significant condition
                            6 (KERN_INFO)           informational
                            7 (KERN_DEBUG)          debug-level messages

            log_buf_len=n[KMG]      Sets the size of the printk ring buffer,
                            in bytes.  n must be a power of two and greater
                            than the minimal size. The minimal size is defined
                            by LOG_BUF_SHIFT kernel config parameter. There is
                            also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
                            that allows to increase the default size depending on
                            the number of CPUs. See init/Kconfig for more details.

            logo.nologo     [FB] Disables display of the built-in Linux logo.
                            This may be used to provide more screen space for
                            kernel log messages and is useful when debugging
                            kernel boot problems.

            lp=0            [LP]    Specify parallel ports to use, e.g,
            lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
            lp=reset                first parallel port). 'lp=0' disables the
            lp=auto                 printer driver. 'lp=reset' (which can be
                                    specified in addition to the ports) causes
                                    attached printers to be reset. Using
                                    lp=port1,port2,... specifies the parallel ports
                                    to associate lp devices with, starting with
                                    lp0. A port specification may be 'none' to skip
                                    that lp device, or a parport name such as
                                    'parport0'. Specifying 'lp=auto' instead of a
                                    port specification list means that device IDs
                                    from each port should be examined, to see if
                                    an IEEE 1284-compliant printer is attached; if
                                    so, the driver will manage that printer.
                                    See also header of drivers/char/lp.c.

            lpj=n           [KNL]
                            Sets loops_per_jiffy to given constant, thus avoiding
                            time-consuming boot-time autodetection (up to 250 ms per
                            CPU). 0 enables autodetection (default). To determine
                            the correct value for your kernel, boot with normal
                            autodetection and see what value is printed. Note that
                            on SMP systems the preset will be applied to all CPUs,
                            which is likely to cause problems if your CPUs need
                            significantly divergent settings. An incorrect value
                            will cause delays in the kernel to be wrong, leading to
                            unpredictable I/O errors and other breakage. Although
                            unlikely, in the extreme case this might damage your
                            hardware.

            ltpc=           [NET]
                            Format: <io>,<irq>,<dma>

            lsm.debug       [SECURITY] Enable LSM initialization debugging output.

            lsm=lsm1,...,lsmN
                            [SECURITY] Choose order of LSM initialization. This
                            overrides CONFIG_LSM, and the "security=" parameter.

            machvec=        [IA-64] Force the use of a particular machine-vector
                            (machvec) in a generic kernel.
                            Example: machvec=hpzx1

            machtype=       [Loongson] Share the same kernel image file between
                            different yeeloong laptops.
                            Example: machtype=lemote-yeeloong-2f-7inch

            max_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory greater
                            than or equal to this physical address is ignored.

            maxcpus=        [SMP] Maximum number of processors that an SMP kernel
                            will bring up during bootup.  maxcpus=n : n >= 0 limits
                            the kernel to bring up 'n' processors. Surely after
                            bootup you can bring up the other plugged cpu by executing
                            "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
                            only takes effect during system bootup.
                            While n=0 is a special case, it is equivalent to "nosmp",
                            which also disables the IO APIC.

            max_loop=       [LOOP] The number of loop block devices that get
            (loop.max_loop) unconditionally pre-created at init time. The default
                            number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
                            of statically allocating a predefined number, loop
                            devices can be requested on-demand with the
                            /dev/loop-control interface.

            mce             [X86-32] Machine Check Exception

            mce=option      [X86-64] See Documentation/x86/x86_64/boot-options.rst

            md=             [HW] RAID subsystems devices and level
                            See Documentation/admin-guide/md.rst.

            mdacon=         [MDA]
                            Format: <first>,<last>
                            Specifies range of consoles to be captured by the MDA.

            mds=            [X86,INTEL]
                            Control mitigation for the Micro-architectural Data
                            Sampling (MDS) vulnerability.

                            Certain CPUs are vulnerable to an exploit against CPU
                            internal buffers which can forward information to a
                            disclosure gadget under certain conditions.

                            In vulnerable processors, the speculatively
                            forwarded data can be used in a cache side channel
                            attack, to access data to which the attacker does
                            not have direct access.

                            This parameter controls the MDS mitigation. The
                            options are:

                            full       - Enable MDS mitigation on vulnerable CPUs
                            full,nosmt - Enable MDS mitigation and disable
                                         SMT on vulnerable CPUs
                            off        - Unconditionally disable MDS mitigation

                            On TAA-affected machines, mds=off can be prevented by
                            an active TAA mitigation as both vulnerabilities are
                            mitigated with the same mechanism so in order to disable
                            this mitigation, you need to specify tsx_async_abort=off
                            too.

                            Not specifying this option is equivalent to
                            mds=full.

                            For details see: Documentation/admin-guide/hw-vuln/mds.rst

            mem=nn[KMG]     [HEXAGON] Set the memory size.
                            Must be specified, otherwise memory size will be 0.

            mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
                            Amount of memory to be used in cases as follows:

                            1 for test;
                            2 when the kernel is not able to see the whole system memory;
                            3 memory that lies after 'mem=' boundary is excluded from
                             the hypervisor, then assigned to KVM guests.
                            4 to limit the memory available for kdump kernel.

                            [ARC,MICROBLAZE] - the limit applies only to low memory,
                            high memory is not affected.

                            [ARM64] - only limits memory covered by the linear
                            mapping. The NOMAP regions are not affected.

                            [X86] Work as limiting max address. Use together
                            with memmap= to avoid physical address space collisions.
                            Without memmap= PCI devices could be placed at addresses
                            belonging to unused RAM.

                            Note that this only takes effects during boot time since
                            in above case 3, memory may need be hot added after boot
                            if system memory of hypervisor is not sufficient.

            mem=nn[KMG]@ss[KMG]
                            [ARM,MIPS] - override the memory layout reported by
                            firmware.
                            Define a memory region of size nn[KMG] starting at
                            ss[KMG].
                            Multiple different regions can be specified with
                            multiple mem= parameters on the command line.

            mem=nopentium   [BUGS=X86-32] Disable usage of 4MB pages for kernel
                            memory.

            memchunk=nn[KMG]
                            [KNL,SH] Allow user to override the default size for
                            per-device physically contiguous DMA buffers.

            memhp_default_state=online/offline
                            [KNL] Set the initial state for the memory hotplug
                            onlining policy. If not specified, the default value is
                            set according to the
                            CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
                            option.
                            See Documentation/admin-guide/mm/memory-hotplug.rst.

            memmap=exactmap [KNL,X86] Enable setting of an exact
                            E820 memory map, as specified by the user.
                            Such memmap=exactmap lines can be constructed based on
                            BIOS output or other requirements. See the memmap=nn@ss
                            option description.

            memmap=nn[KMG]@ss[KMG]
                            [KNL, X86, MIPS, XTENSA] Force usage of a specific region of memory.
                            Region of memory to be used is from ss to ss+nn.
                            If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
                            which limits max address to nn[KMG].
                            Multiple different regions can be specified,
                            comma delimited.
                            Example:
                                    memmap=100M@2G,100M#3G,1G!1024G

            memmap=nn[KMG]#ss[KMG]
                            [KNL,ACPI] Mark specific memory as ACPI data.
                            Region of memory to be marked is from ss to ss+nn.

            memmap=nn[KMG]$ss[KMG]
                            [KNL,ACPI] Mark specific memory as reserved.
                            Region of memory to be reserved is from ss to ss+nn.
                            Example: Exclude memory from 0x18690000-0x1869ffff
                                     memmap=64K$0x18690000
                                     or
                                     memmap=0x10000$0x18690000
                            Some bootloaders may need an escape character before '$',
                            like Grub2, otherwise '$' and the following number
                            will be eaten.

            memmap=nn[KMG]!ss[KMG]
                            [KNL,X86] Mark specific memory as protected.
                            Region of memory to be used, from ss to ss+nn.
                            The memory region may be marked as e820 type 12 (0xc)
                            and is NVDIMM or ADR memory.

            memmap=<size>%<offset>-<oldtype>+<newtype>
                            [KNL,ACPI] Convert memory within the specified region
                            from <oldtype> to <newtype>. If "-<oldtype>" is left
                            out, the whole region will be marked as <newtype>,
                            even if previously unavailable. If "+<newtype>" is left
                            out, matching memory will be removed. Types are
                            specified as e820 types, e.g., 1 = RAM, 2 = reserved,
                            3 = ACPI, 12 = PRAM.

            memory_corruption_check=0/1 [X86]
                            Some BIOSes seem to corrupt the first 64k of
                            memory when doing things like suspend/resume.
                            Setting this option will scan the memory
                            looking for corruption.  Enabling this will
                            both detect corruption and prevent the kernel
                            from using the memory being corrupted.
                            However, its intended as a diagnostic tool; if
                            repeatable BIOS-originated corruption always
                            affects the same memory, you can use memmap=
                            to prevent the kernel from using that memory.

            memory_corruption_check_size=size [X86]
                            By default it checks for corruption in the low
                            64k, making this memory unavailable for normal
                            use.  Use this parameter to scan for
                            corruption in more or less memory.

            memory_corruption_check_period=seconds [X86]
                            By default it checks for corruption every 60
                            seconds.  Use this parameter to check at some
                            other rate.  0 disables periodic checking.

            memory_hotplug.memmap_on_memory
                            [KNL,X86,ARM] Boolean flag to enable this feature.
                            Format: {on | off (default)}
                            When enabled, runtime hotplugged memory will
                            allocate its internal metadata (struct pages)
                            from the hotadded memory which will allow to
                            hotadd a lot of memory without requiring
                            additional memory to do so.
                            This feature is disabled by default because it
                            has some implication on large (e.g. GB)
                            allocations in some configurations (e.g. small
                            memory blocks).
                            The state of the flag can be read in
                            /sys/module/memory_hotplug/parameters/memmap_on_memory.
                            Note that even when enabled, there are a few cases where
                            the feature is not effective.

                            This is not compatible with hugetlb_free_vmemmap. If
                            both parameters are enabled, hugetlb_free_vmemmap takes
                            precedence over memory_hotplug.memmap_on_memory.

            memtest=        [KNL,X86,ARM,M68K,PPC,RISCV] Enable memtest
                            Format: <integer>
                            default : 0 <disable>
                            Specifies the number of memtest passes to be
                            performed. Each pass selects another test
                            pattern from a given set of patterns. Memtest
                            fills the memory with this pattern, validates
                            memory contents and reserves bad memory
                            regions that are detected.

            mem_encrypt=    [X86-64] AMD Secure Memory Encryption (SME) control
                            Valid arguments: on, off
                            Default (depends on kernel configuration option):
                              on  (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y)
                              off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n)
                            mem_encrypt=on:         Activate SME
                            mem_encrypt=off:        Do not activate SME

                            Refer to Documentation/virt/kvm/amd-memory-encryption.rst
                            for details on when memory encryption can be activated.

            mem_sleep_default=      [SUSPEND] Default system suspend mode:
                            s2idle  - Suspend-To-Idle
                            shallow - Power-On Suspend or equivalent (if supported)
                            deep    - Suspend-To-RAM or equivalent (if supported)
                            See Documentation/admin-guide/pm/sleep-states.rst.

            meye.*=         [HW] Set MotionEye Camera parameters
                            See Documentation/admin-guide/media/meye.rst.

            mfgpt_irq=      [IA-32] Specify the IRQ to use for the
                            Multi-Function General Purpose Timers on AMD Geode
                            platforms.

            mfgptfix        [X86-32] Fix MFGPT timers on AMD Geode platforms when
                            the BIOS has incorrectly applied a workaround. TinyBIOS
                            version 0.98 is known to be affected, 0.99 fixes the
                            problem by letting the user disable the workaround.

            mga=            [HW,DRM]

            min_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory below this
                            physical address is ignored.

            mini2440=       [ARM,HW,KNL]
                            Format:[0..2][b][c][t]
                            Default: "0tb"
                            MINI2440 configuration specification:
                            0 - The attached screen is the 3.5" TFT
                            1 - The attached screen is the 7" TFT
                            2 - The VGA Shield is attached (1024x768)
                            Leaving out the screen size parameter will not load
                            the TFT driver, and the framebuffer will be left
                            unconfigured.
                            b - Enable backlight. The TFT backlight pin will be
                            linked to the kernel VESA blanking code and a GPIO
                            LED. This parameter is not necessary when using the
                            VGA shield.
                            c - Enable the s3c camera interface.
                            t - Reserved for enabling touchscreen support. The
                            touchscreen support is not enabled in the mainstream
                            kernel as of 2.6.30, a preliminary port can be found
                            in the "bleeding edge" mini2440 support kernel at
                            https://repo.or.cz/w/linux-2.6/mini2440.git

            mitigations=
                            [X86,PPC,S390,ARM64] Control optional mitigations for
                            CPU vulnerabilities.  This is a set of curated,
                            arch-independent options, each of which is an
                            aggregation of existing arch-specific options.

                            off
                                    Disable all optional CPU mitigations.  This
                                    improves system performance, but it may also
                                    expose users to several CPU vulnerabilities.
                                    Equivalent to: nopti [X86,PPC]
                                                   kpti=0 [ARM64]
                                                   nospectre_v1 [X86,PPC]
                                                   nobp=0 [S390]
                                                   nospectre_v2 [X86,PPC,S390,ARM64]
                                                   spectre_v2_user=off [X86]
                                                   spec_store_bypass_disable=off [X86,PPC]
                                                   ssbd=force-off [ARM64]
                                                   l1tf=off [X86]
                                                   mds=off [X86]
                                                   tsx_async_abort=off [X86]
                                                   kvm.nx_huge_pages=off [X86]
                                                   no_entry_flush [PPC]
                                                   no_uaccess_flush [PPC]
                                                   mmio_stale_data=off [X86]

                                    Exceptions:
                                                   This does not have any effect on
                                                   kvm.nx_huge_pages when
                                                   kvm.nx_huge_pages=force.

                            auto (default)
                                    Mitigate all CPU vulnerabilities, but leave SMT
                                    enabled, even if it's vulnerable.  This is for
                                    users who don't want to be surprised by SMT
                                    getting disabled across kernel upgrades, or who
                                    have other ways of avoiding SMT-based attacks.
                                    Equivalent to: (default behavior)

                            auto,nosmt
                                    Mitigate all CPU vulnerabilities, disabling SMT
                                    if needed.  This is for users who always want to
                                    be fully mitigated, even if it means losing SMT.
                                    Equivalent to: l1tf=flush,nosmt [X86]
                                                   mds=full,nosmt [X86]
                                                   tsx_async_abort=full,nosmt [X86]
                                                   mmio_stale_data=full,nosmt [X86]

            mminit_loglevel=
                            [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
                            parameter allows control of the logging verbosity for
                            the additional memory initialisation checks. A value
                            of 0 disables mminit logging and a level of 4 will
                            log everything. Information is printed at KERN_DEBUG
                            so loglevel=8 may also need to be specified.

            mmio_stale_data=
                            [X86,INTEL] Control mitigation for the Processor
                            MMIO Stale Data vulnerabilities.

                            Processor MMIO Stale Data is a class of
                            vulnerabilities that may expose data after an MMIO
                            operation. Exposed data could originate or end in
                            the same CPU buffers as affected by MDS and TAA.
                            Therefore, similar to MDS and TAA, the mitigation
                            is to clear the affected CPU buffers.

                            This parameter controls the mitigation. The
                            options are:

                            full       - Enable mitigation on vulnerable CPUs

                            full,nosmt - Enable mitigation and disable SMT on
                                         vulnerable CPUs.

                            off        - Unconditionally disable mitigation

                            On MDS or TAA affected machines,
                            mmio_stale_data=off can be prevented by an active
                            MDS or TAA mitigation as these vulnerabilities are
                            mitigated with the same mechanism so in order to
                            disable this mitigation, you need to specify
                            mds=off and tsx_async_abort=off too.

                            Not specifying this option is equivalent to
                            mmio_stale_data=full.

                            For details see:
                            Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst

            module.sig_enforce
                            [KNL] When CONFIG_MODULE_SIG is set, this means that
                            modules without (valid) signatures will fail to load.
                            Note that if CONFIG_MODULE_SIG_FORCE is set, that
                            is always true, so this option does nothing.

            module_blacklist=  [KNL] Do not load a comma-separated list of
                            modules.  Useful for debugging problem modules.

            mousedev.tap_time=
                            [MOUSE] Maximum time between finger touching and
                            leaving touchpad surface for touch to be considered
                            a tap and be reported as a left button click (for
                            touchpads working in absolute mode only).
                            Format: <msecs>
            mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
                            reporting absolute coordinates, such as tablets
            mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
                            reporting absolute coordinates, such as tablets

            movablecore=    [KNL,X86,IA-64,PPC]
                            Format: nn[KMGTPE] | nn%
                            This parameter is the complement to kernelcore=, it
                            specifies the amount of memory used for migratable
                            allocations.  If both kernelcore and movablecore is
                            specified, then kernelcore will be at *least* the
                            specified value but may be more.  If movablecore on its
                            own is specified, the administrator must be careful
                            that the amount of memory usable for all allocations
                            is not too small.

            movable_node    [KNL] Boot-time switch to make hotplugable memory
                            NUMA nodes to be movable. This means that the memory
                            of such nodes will be usable only for movable
                            allocations which rules out almost all kernel
                            allocations. Use with caution!

            MTD_Partition=  [MTD]
                            Format: <name>,<region-number>,<size>,<offset>

            MTD_Region=     [MTD] Format:
                            <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]

            mtdparts=       [MTD]
                            See drivers/mtd/parsers/cmdlinepart.c

            multitce=off    [PPC]  This parameter disables the use of the pSeries
                            firmware feature for updating multiple TCE entries
                            at a time.

            onenand.bdry=   [HW,MTD] Flex-OneNAND Boundary Configuration

                            Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]

                            boundary - index of last SLC block on Flex-OneNAND.
                                       The remaining blocks are configured as MLC blocks.
                            lock     - Configure if Flex-OneNAND boundary should be locked.
                                       Once locked, the boundary cannot be changed.
                                       1 indicates lock status, 0 indicates unlock status.

            mtdset=         [ARM]
                            ARM/S3C2412 JIVE boot control

                            See arch/arm/mach-s3c/mach-jive.c

            mtouchusb.raw_coordinates=
                            [HW] Make the MicroTouch USB driver use raw coordinates
                            ('y', default) or cooked coordinates ('n')

            mtrr_chunk_size=nn[KMG] [X86]
                            used for mtrr cleanup. It is largest continuous chunk
                            that could hold holes aka. UC entries.

            mtrr_gran_size=nn[KMG] [X86]
                            Used for mtrr cleanup. It is granularity of mtrr block.
                            Default is 1.
                            Large value could prevent small alignment from
                            using up MTRRs.

            mtrr_spare_reg_nr=n [X86]
                            Format: <integer>
                            Range: 0,7 : spare reg number
                            Default : 1
                            Used for mtrr cleanup. It is spare mtrr entries number.
                            Set to 2 or more if your graphical card needs more.

            n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card

            netdev=         [NET] Network devices parameters
                            Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
                            Note that mem_start is often overloaded to mean
                            something different and driver-specific.
                            This usage is only documented in each driver source
                            file if at all.

            nf_conntrack.acct=
                            [NETFILTER] Enable connection tracking flow accounting
                            0 to disable accounting
                            1 to enable accounting
                            Default value is 0.

            nfsaddrs=       [NFS] Deprecated.  Use ip= instead.
                            See Documentation/admin-guide/nfs/nfsroot.rst.

            nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
                            See Documentation/admin-guide/nfs/nfsroot.rst.

            nfsrootdebug    [NFS] enable nfsroot debugging messages.
                            See Documentation/admin-guide/nfs/nfsroot.rst.

            nfs.callback_nr_threads=
                            [NFSv4] set the total number of threads that the
                            NFS client will assign to service NFSv4 callback
                            requests.

            nfs.callback_tcpport=
                            [NFS] set the TCP port on which the NFSv4 callback
                            channel should listen.

            nfs.cache_getent=
                            [NFS] sets the pathname to the program which is used
                            to update the NFS client cache entries.

            nfs.cache_getent_timeout=
                            [NFS] sets the timeout after which an attempt to
                            update a cache entry is deemed to have failed.

            nfs.idmap_cache_timeout=
                            [NFS] set the maximum lifetime for idmapper cache
                            entries.

            nfs.enable_ino64=
                            [NFS] enable 64-bit inode numbers.
                            If zero, the NFS client will fake up a 32-bit inode
                            number for the readdir() and stat() syscalls instead
                            of returning the full 64-bit number.
                            The default is to return 64-bit inode numbers.

            nfs.max_session_cb_slots=
                            [NFSv4.1] Sets the maximum number of session
                            slots the client will assign to the callback
                            channel. This determines the maximum number of
                            callbacks the client will process in parallel for
                            a particular server.

            nfs.max_session_slots=
                            [NFSv4.1] Sets the maximum number of session slots
                            the client will attempt to negotiate with the server.
                            This limits the number of simultaneous RPC requests
                            that the client can send to the NFSv4.1 server.
                            Note that there is little point in setting this
                            value higher than the max_tcp_slot_table_limit.

            nfs.nfs4_disable_idmapping=
                            [NFSv4] When set to the default of '1', this option
                            ensures that both the RPC level authentication
                            scheme and the NFS level operations agree to use
                            numeric uids/gids if the mount is using the
                            'sec=sys' security flavour. In effect it is
                            disabling idmapping, which can make migration from
                            legacy NFSv2/v3 systems to NFSv4 easier.
                            Servers that do not support this mode of operation
                            will be autodetected by the client, and it will fall
                            back to using the idmapper.
                            To turn off this behaviour, set the value to '0'.
            nfs.nfs4_unique_id=
                            [NFS4] Specify an additional fixed unique ident-
                            ification string that NFSv4 clients can insert into
                            their nfs_client_id4 string.  This is typically a
                            UUID that is generated at system install time.

            nfs.send_implementation_id =
                            [NFSv4.1] Send client implementation identification
                            information in exchange_id requests.
                            If zero, no implementation identification information
                            will be sent.
                            The default is to send the implementation identification
                            information.

            nfs.recover_lost_locks =
                            [NFSv4] Attempt to recover locks that were lost due
                            to a lease timeout on the server. Please note that
                            doing this risks data corruption, since there are
                            no guarantees that the file will remain unchanged
                            after the locks are lost.
                            If you want to enable the kernel legacy behaviour of
                            attempting to recover these locks, then set this
                            parameter to '1'.
                            The default parameter value of '0' causes the kernel
                            not to attempt recovery of lost locks.

            nfs4.layoutstats_timer =
                            [NFSv4.2] Change the rate at which the kernel sends
                            layoutstats to the pNFS metadata server.

                            Setting this to value to 0 causes the kernel to use
                            whatever value is the default set by the layout
                            driver. A non-zero value sets the minimum interval
                            in seconds between layoutstats transmissions.

            nfsd.inter_copy_offload_enable =
                            [NFSv4.2] When set to 1, the server will support
                            server-to-server copies for which this server is
                            the destination of the copy.

            nfsd.nfsd4_ssc_umount_timeout =
                            [NFSv4.2] When used as the destination of a
                            server-to-server copy, knfsd temporarily mounts
                            the source server.  It caches the mount in case
                            it will be needed again, and discards it if not
                            used for the number of milliseconds specified by
                            this parameter.

            nfsd.nfs4_disable_idmapping=
                            [NFSv4] When set to the default of '1', the NFSv4
                            server will return only numeric uids and gids to
                            clients using auth_sys, and will accept numeric uids
                            and gids from such clients.  This is intended to ease
                            migration from NFSv2/v3.

            nmi_backtrace.backtrace_idle [KNL]
                            Dump stacks even of idle CPUs in response to an
                            NMI stack-backtrace request.

            nmi_debug=      [KNL,SH] Specify one or more actions to take
                            when a NMI is triggered.
                            Format: [state][,regs][,debounce][,die]

            nmi_watchdog=   [KNL,BUGS=X86] Debugging features for SMP kernels
                            Format: [panic,][nopanic,][num]
                            Valid num: 0 or 1
                            0 - turn hardlockup detector in nmi_watchdog off
                            1 - turn hardlockup detector in nmi_watchdog on
                            When panic is specified, panic when an NMI watchdog
                            timeout occurs (or 'nopanic' to not panic on an NMI
                            watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
                            To disable both hard and soft lockup detectors,
                            please see 'nowatchdog'.
                            This is useful when you use a panic=... timeout and
                            need the box quickly up again.

                            These settings can be accessed at runtime via
                            the nmi_watchdog and hardlockup_panic sysctls.

            netpoll.carrier_timeout=
                            [NET] Specifies amount of time (in seconds) that
                            netpoll should wait for a carrier. By default netpoll
                            waits 4 seconds.

            no387           [BUGS=X86-32] Tells the kernel to use the 387 maths
                            emulation library even if a 387 maths coprocessor
                            is present.

            no5lvl          [X86-64] Disable 5-level paging mode. Forces
                            kernel to use 4-level paging instead.

            nofsgsbase      [X86] Disables FSGSBASE instructions.

            no_console_suspend
                            [HW] Never suspend the console
                            Disable suspending of consoles during suspend and
                            hibernate operations.  Once disabled, debugging
                            messages can reach various consoles while the rest
                            of the system is being put to sleep (ie, while
                            debugging driver suspend/resume hooks).  This may
                            not work reliably with all consoles, but is known
                            to work with serial and VGA consoles.
                            To facilitate more flexible debugging, we also add
                            console_suspend, a printk module parameter to control
                            it. Users could use console_suspend (usually
                            /sys/module/printk/parameters/console_suspend) to
                            turn on/off it dynamically.

            novmcoredd      [KNL,KDUMP]
                            Disable device dump. Device dump allows drivers to
                            append dump data to vmcore so you can collect driver
                            specified debug info.  Drivers can append the data
                            without any limit and this data is stored in memory,
                            so this may cause significant memory stress.  Disabling
                            device dump can help save memory but the driver debug
                            data will be no longer available.  This parameter
                            is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP
                            is set.

            noaliencache    [MM, NUMA, SLAB] Disables the allocation of alien
                            caches in the slab allocator.  Saves per-node memory,
                            but will impact performance.

            noalign         [KNL,ARM]

            noaltinstr      [S390] Disables alternative instructions patching
                            (CPU alternatives feature).

            noapic          [SMP,APIC] Tells the kernel to not make use of any
                            IOAPICs that may be present in the system.

            noautogroup     Disable scheduler automatic task group creation.

            nobats          [PPC] Do not use BATs for mapping kernel lowmem
                            on "Classic" PPC cores.

            nocache         [ARM]

            noclflush       [BUGS=X86] Don't use the CLFLUSH instruction

            delayacct       [KNL] Enable per-task delay accounting

            nodsp           [SH] Disable hardware DSP at boot time.

            noefi           Disable EFI runtime services support.

            no_entry_flush  [PPC] Don't flush the L1-D cache when entering the kernel.

            noexec          [IA-64]

            noexec          [X86]
                            On X86-32 available only on PAE configured kernels.
                            noexec=on: enable non-executable mappings (default)
                            noexec=off: disable non-executable mappings

            nosmap          [X86,PPC]
                            Disable SMAP (Supervisor Mode Access Prevention)
                            even if it is supported by processor.

            nosmep          [X86,PPC64s]
                            Disable SMEP (Supervisor Mode Execution Prevention)
                            even if it is supported by processor.

            noexec32        [X86-64]
                            This affects only 32-bit executables.
                            noexec32=on: enable non-executable mappings (default)
                                    read doesn't imply executable mappings
                            noexec32=off: disable non-executable mappings
                                    read implies executable mappings

            nofpu           [MIPS,SH] Disable hardware FPU at boot time.

            nofxsr          [BUGS=X86-32] Disables x86 floating point extended
                            register save and restore. The kernel will only save
                            legacy floating-point registers on task switch.

            nohugeiomap     [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.

            nohugevmalloc   [PPC] Disable kernel huge vmalloc mappings.

            nosmt           [KNL,S390] Disable symmetric multithreading (SMT).
                            Equivalent to smt=1.

                            [KNL,X86] Disable symmetric multithreading (SMT).
                            nosmt=force: Force disable SMT, cannot be undone
                                         via the sysfs control file.

            nospectre_v1    [X86,PPC] Disable mitigations for Spectre Variant 1
                            (bounds check bypass). With this option data leaks are
                            possible in the system.

            nospectre_v2    [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
                            the Spectre variant 2 (indirect branch prediction)
                            vulnerability. System may allow data leaks with this
                            option.

            nospec_store_bypass_disable
                            [HW] Disable all mitigations for the Speculative Store Bypass vulnerability

            no_uaccess_flush
                            [PPC] Don't flush the L1-D cache after accessing user data.

            noxsave         [BUGS=X86] Disables x86 extended register state save
                            and restore using xsave. The kernel will fallback to
                            enabling legacy floating-point and sse state.

            noxsaveopt      [X86] Disables xsaveopt used in saving x86 extended
                            register states. The kernel will fall back to use
                            xsave to save the states. By using this parameter,
                            performance of saving the states is degraded because
                            xsave doesn't support modified optimization while
                            xsaveopt supports it on xsaveopt enabled systems.

            noxsaves        [X86] Disables xsaves and xrstors used in saving and
                            restoring x86 extended register state in compacted
                            form of xsave area. The kernel will fall back to use
                            xsaveopt and xrstor to save and restore the states
                            in standard form of xsave area. By using this
                            parameter, xsave area per process might occupy more
                            memory on xsaves enabled systems.

            nohlt           [ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait
                            in do_idle() and not use the arch_cpu_idle()
                            implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
                            to be effective. This is useful on platforms where the
                            sleep(SH) or wfi(ARM,ARM64) instructions do not work
                            correctly or when doing power measurements to evalute
                            the impact of the sleep instructions. This is also
                            useful when using JTAG debugger.

            no_file_caps    Tells the kernel not to honor file capabilities.  The
                            only way then for a file to be executed with privilege
                            is to be setuid root or executed by root.

            nohalt          [IA-64] Tells the kernel not to use the power saving
                            function PAL_HALT_LIGHT when idle. This increases
                            power-consumption. On the positive side, it reduces
                            interrupt wake-up latency, which may improve performance
                            in certain environments such as networked servers or
                            real-time systems.

            no_hash_pointers
                            Force pointers printed to the console or buffers to be
                            unhashed.  By default, when a pointer is printed via %p
                            format string, that pointer is "hashed", i.e. obscured
                            by hashing the pointer value.  This is a security feature
                            that hides actual kernel addresses from unprivileged
                            users, but it also makes debugging the kernel more
                            difficult since unequal pointers can no longer be
                            compared.  However, if this command-line option is
                            specified, then all normal pointers will have their true
                            value printed. This option should only be specified when
                            debugging the kernel.  Please do not use on production
                            kernels.

            nohibernate     [HIBERNATION] Disable hibernation and resume.

            nohz=           [KNL] Boottime enable/disable dynamic ticks
                            Valid arguments: on, off
                            Default: on

            nohz_full=      [KNL,BOOT,SMP,ISOL]
                            The argument is a cpu list, as described above.
                            In kernels built with CONFIG_NO_HZ_FULL=y, set
                            the specified list of CPUs whose tick will be stopped
                            whenever possible. The boot CPU will be forced outside
                            the range to maintain the timekeeping.  Any CPUs
                            in this list will have their RCU callbacks offloaded,
                            just as if they had also been called out in the
                            rcu_nocbs= boot parameter.

            noiotrap        [SH] Disables trapped I/O port accesses.

            noirqdebug      [X86-32] Disables the code which attempts to detect and
                            disable unhandled interrupt sources.

            no_timer_check  [X86,APIC] Disables the code which tests for
                            broken timer IRQ sources.

            noisapnp        [ISAPNP] Disables ISA PnP code.

            noinitrd        [RAM] Tells the kernel not to load any configured
                            initial RAM disk.

            nointremap      [X86-64, Intel-IOMMU] Do not enable interrupt
                            remapping.
                            [Deprecated - use intremap=off]

            nointroute      [IA-64]

            noinvpcid       [X86] Disable the INVPCID cpu feature.

            nojitter        [IA-64] Disables jitter checking for ITC timers.

            no-kvmclock     [X86,KVM] Disable paravirtualized KVM clock driver

            no-kvmapf       [X86,KVM] Disable paravirtualized asynchronous page
                            fault handling.

            no-vmw-sched-clock
                            [X86,PV_OPS] Disable paravirtualized VMware scheduler
                            clock and use the default one.

            no-steal-acc    [X86,PV_OPS,ARM64] Disable paravirtualized steal time
                            accounting. steal time is computed, but won't
                            influence scheduler behaviour

            nolapic         [X86-32,APIC] Do not enable or use the local APIC.

            nolapic_timer   [X86-32,APIC] Do not use the local APIC timer.

            noltlbs         [PPC] Do not use large page/tlb entries for kernel
                            lowmem mapping on PPC40x and PPC8xx

            nomca           [IA-64] Disable machine check abort handling

            nomce           [X86-32] Disable Machine Check Exception

            nomfgpt         [X86-32] Disable Multi-Function General Purpose
                            Timer usage (for AMD Geode machines).

            nonmi_ipi       [X86] Disable using NMI IPIs during panic/reboot to
                            shutdown the other cpus.  Instead use the REBOOT_VECTOR
                            irq.

            nomodeset       Disable kernel modesetting. DRM drivers will not perform
                            display-mode changes or accelerated rendering. Only the
                            system framebuffer will be available for use if this was
                            set-up by the firmware or boot loader.

                            Useful as fallback, or for testing and debugging.

            nomodule        Disable module load

            nopat           [X86] Disable PAT (page attribute table extension of
                            pagetables) support.

            nopcid          [X86-64] Disable the PCID cpu feature.

            norandmaps      Don't use address space randomization.  Equivalent to
                            echo 0 > /proc/sys/kernel/randomize_va_space

            noreplace-smp   [X86-32,SMP] Don't replace SMP instructions
                            with UP alternatives

            nordrand        [X86] Disable kernel use of the RDRAND and
                            RDSEED instructions even if they are supported
                            by the processor.  RDRAND and RDSEED are still
                            available to user space applications.

            noresume        [SWSUSP] Disables resume and restores original swap
                            space.

            no-scroll       [VGA] Disables scrollback.
                            This is required for the Braillex ib80-piezo Braille
                            reader made by F.H. Papenmeier (Germany).

            nosbagart       [IA-64]

            nosep           [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.

            nosgx           [X86-64,SGX] Disables Intel SGX kernel support.

            nosmp           [SMP] Tells an SMP kernel to act as a UP kernel,
                            and disable the IO APIC.  legacy for "maxcpus=0".

            nosoftlockup    [KNL] Disable the soft-lockup detector.

            nosync          [HW,M68K] Disables sync negotiation for all devices.

            nowatchdog      [KNL] Disable both lockup detectors, i.e.
                            soft-lockup and NMI watchdog (hard-lockup).

            nowb            [ARM]

            nox2apic        [X86-64,APIC] Do not enable x2APIC mode.

            cpu0_hotplug    [X86] Turn on CPU0 hotplug feature when
                            CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
                            Some features depend on CPU0. Known dependencies are:
                            1. Resume from suspend/hibernate depends on CPU0.
                            Suspend/hibernate will fail if CPU0 is offline and you
                            need to online CPU0 before suspend/hibernate.
                            2. PIC interrupts also depend on CPU0. CPU0 can't be
                            removed if a PIC interrupt is detected.
                            It's said poweroff/reboot may depend on CPU0 on some
                            machines although I haven't seen such issues so far
                            after CPU0 is offline on a few tested machines.
                            If the dependencies are under your control, you can
                            turn on cpu0_hotplug.

            nps_mtm_hs_ctr= [KNL,ARC]
                            This parameter sets the maximum duration, in
                            cycles, each HW thread of the CTOP can run
                            without interruptions, before HW switches it.
                            The actual maximum duration is 16 times this
                            parameter's value.
                            Format: integer between 1 and 255
                            Default: 255

            nptcg=          [IA-64] Override max number of concurrent global TLB
                            purges which is reported from either PAL_VM_SUMMARY or
                            SAL PALO.

            nr_cpus=        [SMP] Maximum number of processors that an SMP kernel
                            could support.  nr_cpus=n : n >= 1 limits the kernel to
                            support 'n' processors. It could be larger than the
                            number of already plugged CPU during bootup, later in
                            runtime you can physically add extra cpu until it reaches
                            n. So during boot up some boot time memory for per-cpu
                            variables need be pre-allocated for later physical cpu
                            hot plugging.

            nr_uarts=       [SERIAL] maximum number of UARTs to be registered.

            numa=off        [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
                            set up a single NUMA node spanning all memory.

            numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
                            NUMA balancing.
                            Allowed values are enable and disable

            numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
                            'node', 'default' can be specified
                            This can be set from sysctl after boot.
                            See Documentation/admin-guide/sysctl/vm.rst for details.

            ohci1394_dma=early      [HW] enable debugging via the ohci1394 driver.
                            See Documentation/core-api/debugging-via-ohci1394.rst for more
                            info.

            olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
                            Rather than timing out after 20 ms if an EC
                            command is not properly ACKed, override the length
                            of the timeout.  We have interrupts disabled while
                            waiting for the ACK, so if this is set too high
                            interrupts *may* be lost!

            omap_mux=       [OMAP] Override bootloader pin multiplexing.
                            Format: <mux_mode0.mode_name=value>...
                            For example, to override I2C bus2:
                            omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100

            oops=panic      Always panic on oopses. Default is to just kill the
                            process, but there is a small probability of
                            deadlocking the machine.
                            This will also cause panics on machine check exceptions.
                            Useful together with panic=30 to trigger a reboot.

            page_alloc.shuffle=
                            [KNL] Boolean flag to control whether the page allocator
                            should randomize its free lists. The randomization may
                            be automatically enabled if the kernel detects it is
                            running on a platform with a direct-mapped memory-side
                            cache, and this parameter can be used to
                            override/disable that behavior. The state of the flag
                            can be read from sysfs at:
                            /sys/module/page_alloc/parameters/shuffle.

            page_owner=     [KNL] Boot-time page_owner enabling option.
                            Storage of the information about who allocated
                            each page is disabled in default. With this switch,
                            we can turn it on.
                            on: enable the feature

            page_poison=    [KNL] Boot-time parameter changing the state of
                            poisoning on the buddy allocator, available with
                            CONFIG_PAGE_POISONING=y.
                            off: turn off poisoning (default)
                            on: turn on poisoning

            page_reporting.page_reporting_order=
                            [KNL] Minimal page reporting order
                            Format: <integer>
                            Adjust the minimal page reporting order. The page
                            reporting is disabled when it exceeds (MAX_ORDER-1).

            panic=          [KNL] Kernel behaviour on panic: delay <timeout>
                            timeout > 0: seconds before rebooting
                            timeout = 0: wait forever
                            timeout < 0: reboot immediately
                            Format: <timeout>

            panic_print=    Bitmask for printing system info when panic happens.
                            User can chose combination of the following bits:
                            bit 0: print all tasks info
                            bit 1: print system memory info
                            bit 2: print timer info
                            bit 3: print locks info if CONFIG_LOCKDEP is on
                            bit 4: print ftrace buffer
                            bit 5: print all printk messages in buffer
                            bit 6: print all CPUs backtrace (if available in the arch)
                            *Be aware* that this option may print a _lot_ of lines,
                            so there are risks of losing older messages in the log.
                            Use this option carefully, maybe worth to setup a
                            bigger log buffer with "log_buf_len" along with this.

            panic_on_taint= Bitmask for conditionally calling panic() in add_taint()
                            Format: <hex>[,nousertaint]
                            Hexadecimal bitmask representing the set of TAINT flags
                            that will cause the kernel to panic when add_taint() is
                            called with any of the flags in this set.
                            The optional switch "nousertaint" can be utilized to
                            prevent userspace forced crashes by writing to sysctl
                            /proc/sys/kernel/tainted any flagset matching with the
                            bitmask set on panic_on_taint.
                            See Documentation/admin-guide/tainted-kernels.rst for
                            extra details on the taint flags that users can pick
                            to compose the bitmask to assign to panic_on_taint.

            panic_on_warn   panic() instead of WARN().  Useful to cause kdump
                            on a WARN().

            crash_kexec_post_notifiers
                            Run kdump after running panic-notifiers and dumping
                            kmsg. This only for the users who doubt kdump always
                            succeeds in any situation.
                            Note that this also increases risks of kdump failure,
                            because some panic notifiers can make the crashed
                            kernel more unstable.

            parkbd.port=    [HW] Parallel port number the keyboard adapter is
                            connected to, default is 0.
                            Format: <parport#>
            parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
                            0 for XT, 1 for AT (default is AT).
                            Format: <mode>

            parport=        [HW,PPT] Specify parallel ports. 0 disables.
                            Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
                            Use 'auto' to force the driver to use any
                            IRQ/DMA settings detected (the default is to
                            ignore detected IRQ/DMA settings because of
                            possible conflicts). You can specify the base
                            address, IRQ, and DMA settings; IRQ and DMA
                            should be numbers, or 'auto' (for using detected
                            settings on that particular port), or 'nofifo'
                            (to avoid using a FIFO even if it is detected).
                            Parallel ports are assigned in the order they
                            are specified on the command line, starting
                            with parport0.

            parport_init_mode=      [HW,PPT]
                            Configure VIA parallel port to operate in
                            a specific mode. This is necessary on Pegasos
                            computer where firmware has no options for setting
                            up parallel port mode and sets it to spp.
                            Currently this function knows 686a and 8231 chips.
                            Format: [spp|ps2|epp|ecp|ecpepp]

            pata_legacy.all=        [HW,LIBATA]
                            Format: <int>
                            Set to non-zero to probe primary and secondary ISA
                            port ranges on PCI systems where no PCI PATA device
                            has been found at either range.  Disabled by default.

            pata_legacy.autospeed=  [HW,LIBATA]
                            Format: <int>
                            Set to non-zero if a chip is present that snoops speed
                            changes.  Disabled by default.

            pata_legacy.ht6560a=    [HW,LIBATA]
                            Format: <int>
                            Set to 1, 2, or 3 for HT 6560A on the primary channel,
                            the secondary channel, or both channels respectively.
                            Disabled by default.

            pata_legacy.ht6560b=    [HW,LIBATA]
                            Format: <int>
                            Set to 1, 2, or 3 for HT 6560B on the primary channel,
                            the secondary channel, or both channels respectively.
                            Disabled by default.

            pata_legacy.iordy_mask= [HW,LIBATA]
                            Format: <int>
                            IORDY enable mask.  Set individual bits to allow IORDY
                            for the respective channel.  Bit 0 is for the first
                            legacy channel handled by this driver, bit 1 is for
                            the second channel, and so on.  The sequence will often
                            correspond to the primary legacy channel, the secondary
                            legacy channel, and so on, but the handling of a PCI
                            bus and the use of other driver options may interfere
                            with the sequence.  By default IORDY is allowed across
                            all channels.

            pata_legacy.opti82c46x= [HW,LIBATA]
                            Format: <int>
                            Set to 1, 2, or 3 for Opti 82c611A on the primary
                            channel, the secondary channel, or both channels
                            respectively.  Disabled by default.

            pata_legacy.opti82c611a=        [HW,LIBATA]
                            Format: <int>
                            Set to 1, 2, or 3 for Opti 82c465MV on the primary
                            channel, the secondary channel, or both channels
                            respectively.  Disabled by default.

            pata_legacy.pio_mask=   [HW,LIBATA]
                            Format: <int>
                            PIO mode mask for autospeed devices.  Set individual
                            bits to allow the use of the respective PIO modes.
                            Bit 0 is for mode 0, bit 1 is for mode 1, and so on.
                            All modes allowed by default.

            pata_legacy.probe_all=  [HW,LIBATA]
                            Format: <int>
                            Set to non-zero to probe tertiary and further ISA
                            port ranges on PCI systems.  Disabled by default.

            pata_legacy.probe_mask= [HW,LIBATA]
                            Format: <int>
                            Probe mask for legacy ISA PATA ports.  Depending on
                            platform configuration and the use of other driver
                            options up to 6 legacy ports are supported: 0x1f0,
                            0x170, 0x1e8, 0x168, 0x1e0, 0x160, however probing
                            of individual ports can be disabled by setting the
                            corresponding bits in the mask to 1.  Bit 0 is for
                            the first port in the list above (0x1f0), and so on.
                            By default all supported ports are probed.

            pata_legacy.qdi=        [HW,LIBATA]
                            Format: <int>
                            Set to non-zero to probe QDI controllers.  By default
                            set to 1 if CONFIG_PATA_QDI_MODULE, 0 otherwise.

            pata_legacy.winbond=    [HW,LIBATA]
                            Format: <int>
                            Set to non-zero to probe Winbond controllers.  Use
                            the standard I/O port (0x130) if 1, otherwise the
                            value given is the I/O port to use (typically 0x1b0).
                            By default set to 1 if CONFIG_PATA_WINBOND_VLB_MODULE,
                            0 otherwise.

            pata_platform.pio_mask= [HW,LIBATA]
                            Format: <int>
                            Supported PIO mode mask.  Set individual bits to allow
                            the use of the respective PIO modes.  Bit 0 is for
                            mode 0, bit 1 is for mode 1, and so on.  Mode 0 only
                            allowed by default.

            pause_on_oops=
                            Halt all CPUs after the first oops has been printed for
                            the specified number of seconds.  This is to be used if
                            your oopses keep scrolling off the screen.

            pcbit=          [HW,ISDN]

            pcd.            [PARIDE]
                            See header of drivers/block/paride/pcd.c.
                            See also Documentation/admin-guide/blockdev/paride.rst.

            pci=option[,option...]  [PCI] various PCI subsystem options.

                                    Some options herein operate on a specific device
                                    or a set of devices (<pci_dev>). These are
                                    specified in one of the following formats:

                                    [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]*
                                    pci:<vendor>:<device>[:<subvendor>:<subdevice>]

                                    Note: the first format specifies a PCI
                                    bus/device/function address which may change
                                    if new hardware is inserted, if motherboard
                                    firmware changes, or due to changes caused
                                    by other kernel parameters. If the
                                    domain is left unspecified, it is
                                    taken to be zero. Optionally, a path
                                    to a device through multiple device/function
                                    addresses can be specified after the base
                                    address (this is more robust against
                                    renumbering issues).  The second format
                                    selects devices using IDs from the
                                    configuration space which may match multiple
                                    devices in the system.

                    earlydump       dump PCI config space before the kernel
                                    changes anything
                    off             [X86] don't probe for the PCI bus
                    bios            [X86-32] force use of PCI BIOS, don't access
                                    the hardware directly. Use this if your machine
                                    has a non-standard PCI host bridge.
                    nobios          [X86-32] disallow use of PCI BIOS, only direct
                                    hardware access methods are allowed. Use this
                                    if you experience crashes upon bootup and you
                                    suspect they are caused by the BIOS.
                    conf1           [X86] Force use of PCI Configuration Access
                                    Mechanism 1 (config address in IO port 0xCF8,
                                    data in IO port 0xCFC, both 32-bit).
                    conf2           [X86] Force use of PCI Configuration Access
                                    Mechanism 2 (IO port 0xCF8 is an 8-bit port for
                                    the function, IO port 0xCFA, also 8-bit, sets
                                    bus number. The config space is then accessed
                                    through ports 0xC000-0xCFFF).
                                    See http://wiki.osdev.org/PCI for more info
                                    on the configuration access mechanisms.
                    noaer           [PCIE] If the PCIEAER kernel config parameter is
                                    enabled, this kernel boot option can be used to
                                    disable the use of PCIE advanced error reporting.
                    nodomains       [PCI] Disable support for multiple PCI
                                    root domains (aka PCI segments, in ACPI-speak).
                    nommconf        [X86] Disable use of MMCONFIG for PCI
                                    Configuration
                    check_enable_amd_mmconf [X86] check for and enable
                                    properly configured MMIO access to PCI
                                    config space on AMD family 10h CPU
                    nomsi           [MSI] If the PCI_MSI kernel config parameter is
                                    enabled, this kernel boot option can be used to
                                    disable the use of MSI interrupts system-wide.
                    noioapicquirk   [APIC] Disable all boot interrupt quirks.
                                    Safety option to keep boot IRQs enabled. This
                                    should never be necessary.
                    ioapicreroute   [APIC] Enable rerouting of boot IRQs to the
                                    primary IO-APIC for bridges that cannot disable
                                    boot IRQs. This fixes a source of spurious IRQs
                                    when the system masks IRQs.
                    noioapicreroute [APIC] Disable workaround that uses the
                                    boot IRQ equivalent of an IRQ that connects to
                                    a chipset where boot IRQs cannot be disabled.
                                    The opposite of ioapicreroute.
                    biosirq         [X86-32] Use PCI BIOS calls to get the interrupt
                                    routing table. These calls are known to be buggy
                                    on several machines and they hang the machine
                                    when used, but on other computers it's the only
                                    way to get the interrupt routing table. Try
                                    this option if the kernel is unable to allocate
                                    IRQs or discover secondary PCI buses on your
                                    motherboard.
                    rom             [X86] Assign address space to expansion ROMs.
                                    Use with caution as certain devices share
                                    address decoders between ROMs and other
                                    resources.
                    norom           [X86] Do not assign address space to
                                    expansion ROMs that do not already have
                                    BIOS assigned address ranges.
                    nobar           [X86] Do not assign address space to the
                                    BARs that weren't assigned by the BIOS.
                    irqmask=0xMMMM  [X86] Set a bit mask of IRQs allowed to be
                                    assigned automatically to PCI devices. You can
                                    make the kernel exclude IRQs of your ISA cards
                                    this way.
                    pirqaddr=0xAAAAA        [X86] Specify the physical address
                                    of the PIRQ table (normally generated
                                    by the BIOS) if it is outside the
                                    F0000h-100000h range.
                    lastbus=N       [X86] Scan all buses thru bus #N. Can be
                                    useful if the kernel is unable to find your
                                    secondary buses and you want to tell it
                                    explicitly which ones they are.
                    assign-busses   [X86] Always assign all PCI bus
                                    numbers ourselves, overriding
                                    whatever the firmware may have done.
                    usepirqmask     [X86] Honor the possible IRQ mask stored
                                    in the BIOS $PIR table. This is needed on
                                    some systems with broken BIOSes, notably
                                    some HP Pavilion N5400 and Omnibook XE3
                                    notebooks. This will have no effect if ACPI
                                    IRQ routing is enabled.
                    noacpi          [X86] Do not use ACPI for IRQ routing
                                    or for PCI scanning.
                    use_crs         [X86] Use PCI host bridge window information
                                    from ACPI.  On BIOSes from 2008 or later, this
                                    is enabled by default.  If you need to use this,
                                    please report a bug.
                    nocrs           [X86] Ignore PCI host bridge windows from ACPI.
                                    If you need to use this, please report a bug.
                    routeirq        Do IRQ routing for all PCI devices.
                                    This is normally done in pci_enable_device(),
                                    so this option is a temporary workaround
                                    for broken drivers that don't call it.
                    skip_isa_align  [X86] do not align io start addr, so can
                                    handle more pci cards
                    noearly         [X86] Don't do any early type 1 scanning.
                                    This might help on some broken boards which
                                    machine check when some devices' config space
                                    is read. But various workarounds are disabled
                                    and some IOMMU drivers will not work.
                    bfsort          Sort PCI devices into breadth-first order.
                                    This sorting is done to get a device
                                    order compatible with older (<= 2.4) kernels.
                    nobfsort        Don't sort PCI devices into breadth-first order.
                    pcie_bus_tune_off       Disable PCIe MPS (Max Payload Size)
                                    tuning and use the BIOS-configured MPS defaults.
                    pcie_bus_safe   Set every device's MPS to the largest value
                                    supported by all devices below the root complex.
                    pcie_bus_perf   Set device MPS to the largest allowable MPS
                                    based on its parent bus. Also set MRRS (Max
                                    Read Request Size) to the largest supported
                                    value (no larger than the MPS that the device
                                    or bus can support) for best performance.
                    pcie_bus_peer2peer      Set every device's MPS to 128B, which
                                    every device is guaranteed to support. This
                                    configuration allows peer-to-peer DMA between
                                    any pair of devices, possibly at the cost of
                                    reduced performance.  This also guarantees
                                    that hot-added devices will work.
                    cbiosize=nn[KMG]        The fixed amount of bus space which is
                                    reserved for the CardBus bridge's IO window.
                                    The default value is 256 bytes.
                    cbmemsize=nn[KMG]       The fixed amount of bus space which is
                                    reserved for the CardBus bridge's memory
                                    window. The default value is 64 megabytes.
                    resource_alignment=
                                    Format:
                                    [<order of align>@]<pci_dev>[; ...]
                                    Specifies alignment and device to reassign
                                    aligned memory resources. How to
                                    specify the device is described above.
                                    If <order of align> is not specified,
                                    PAGE_SIZE is used as alignment.
                                    A PCI-PCI bridge can be specified if resource
                                    windows need to be expanded.
                                    To specify the alignment for several
                                    instances of a device, the PCI vendor,
                                    device, subvendor, and subdevice may be
                                    specified, e.g., 12@pci:8086:9c22:103c:198f
                                    for 4096-byte alignment.
                    ecrc=           Enable/disable PCIe ECRC (transaction layer
                                    end-to-end CRC checking).
                                    bios: Use BIOS/firmware settings. This is the
                                    the default.
                                    off: Turn ECRC off
                                    on: Turn ECRC on.
                    hpiosize=nn[KMG]        The fixed amount of bus space which is
                                    reserved for hotplug bridge's IO window.
                                    Default size is 256 bytes.
                    hpmmiosize=nn[KMG]      The fixed amount of bus space which is
                                    reserved for hotplug bridge's MMIO window.
                                    Default size is 2 megabytes.
                    hpmmioprefsize=nn[KMG]  The fixed amount of bus space which is
                                    reserved for hotplug bridge's MMIO_PREF window.
                                    Default size is 2 megabytes.
                    hpmemsize=nn[KMG]       The fixed amount of bus space which is
                                    reserved for hotplug bridge's MMIO and
                                    MMIO_PREF window.
                                    Default size is 2 megabytes.
                    hpbussize=nn    The minimum amount of additional bus numbers
                                    reserved for buses below a hotplug bridge.
                                    Default is 1.
                    realloc=        Enable/disable reallocating PCI bridge resources
                                    if allocations done by BIOS are too small to
                                    accommodate resources required by all child
                                    devices.
                                    off: Turn realloc off
                                    on: Turn realloc on
                    realloc         same as realloc=on
                    noari           do not use PCIe ARI.
                    noats           [PCIE, Intel-IOMMU, AMD-IOMMU]
                                    do not use PCIe ATS (and IOMMU device IOTLB).
                    pcie_scan_all   Scan all possible PCIe devices.  Otherwise we
                                    only look for one device below a PCIe downstream
                                    port.
                    big_root_window Try to add a big 64bit memory window to the PCIe
                                    root complex on AMD CPUs. Some GFX hardware
                                    can resize a BAR to allow access to all VRAM.
                                    Adding the window is slightly risky (it may
                                    conflict with unreported devices), so this
                                    taints the kernel.
                    disable_acs_redir=<pci_dev>[; ...]
                                    Specify one or more PCI devices (in the format
                                    specified above) separated by semicolons.
                                    Each device specified will have the PCI ACS
                                    redirect capabilities forced off which will
                                    allow P2P traffic between devices through
                                    bridges without forcing it upstream. Note:
                                    this removes isolation between devices and
                                    may put more devices in an IOMMU group.
                    force_floating  [S390] Force usage of floating interrupts.
                    nomio           [S390] Do not use MIO instructions.
                    norid           [S390] ignore the RID field and force use of
                                    one PCI domain per PCI function

            pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State Power
                            Management.
                    off     Disable ASPM.
                    force   Enable ASPM even on devices that claim not to support it.
                            WARNING: Forcing ASPM on may cause system lockups.

            pcie_ports=     [PCIE] PCIe port services handling:
                    native  Use native PCIe services (PME, AER, DPC, PCIe hotplug)
                            even if the platform doesn't give the OS permission to
                            use them.  This may cause conflicts if the platform
                            also tries to use these services.
                    dpc-native      Use native PCIe service for DPC only.  May
                                    cause conflicts if firmware uses AER or DPC.
                    compat  Disable native PCIe services (PME, AER, DPC, PCIe
                            hotplug).

            pcie_port_pm=   [PCIE] PCIe port power management handling:
                    off     Disable power management of all PCIe ports
                    force   Forcibly enable power management of all PCIe ports

            pcie_pme=       [PCIE,PM] Native PCIe PME signaling options:
                    nomsi   Do not use MSI for native PCIe PME signaling (this makes
                            all PCIe root ports use INTx for all services).

            pcmv=           [HW,PCMCIA] BadgePAD 4

            pd_ignore_unused
                            [PM]
                            Keep all power-domains already enabled by bootloader on,
                            even if no driver has claimed them. This is useful
                            for debug and development, but should not be
                            needed on a platform with proper driver support.

            pd.             [PARIDE]
                            See Documentation/admin-guide/blockdev/paride.rst.

            pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
                            boot time.
                            Format: { 0 | 1 }
                            See arch/parisc/kernel/pdc_chassis.c

            percpu_alloc=   Select which percpu first chunk allocator to use.
                            Currently supported values are "embed" and "page".
                            Archs may support subset or none of the selections.
                            See comments in mm/percpu.c for details on each
                            allocator.  This parameter is primarily for debugging
                            and performance comparison.

            pf.             [PARIDE]
                            See Documentation/admin-guide/blockdev/paride.rst.

            pg.             [PARIDE]
                            See Documentation/admin-guide/blockdev/paride.rst.

            pirq=           [SMP,APIC] Manual mp-table setup
                            See Documentation/x86/i386/IO-APIC.rst.

            plip=           [PPT,NET] Parallel port network link
                            Format: { parport<nr> | timid | 0 }
                            See also Documentation/admin-guide/parport.rst.

            pmtmr=          [X86] Manual setup of pmtmr I/O Port.
                            Override pmtimer IOPort with a hex value.
                            e.g. pmtmr=0x508

            pmu_override=   [PPC] Override the PMU.
                            This option takes over the PMU facility, so it is no
                            longer usable by perf. Setting this option starts the
                            PMU counters by setting MMCR0 to 0 (the FC bit is
                            cleared). If a number is given, then MMCR1 is set to
                            that number, otherwise (e.g., 'pmu_override=on'), MMCR1
                            remains 0.

            pm_debug_messages       [SUSPEND,KNL]
                            Enable suspend/resume debug messages during boot up.

            pnp.debug=1     [PNP]
                            Enable PNP debug messages (depends on the
                            CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
                            via /sys/module/pnp/parameters/debug.  We always show
                            current resource usage; turning this on also shows
                            possible settings and some assignment information.

            pnpacpi=        [ACPI]
                            { off }

            pnpbios=        [ISAPNP]
                            { on | off | curr | res | no-curr | no-res }

            pnp_reserve_irq=
                            [ISAPNP] Exclude IRQs for the autoconfiguration

            pnp_reserve_dma=
                            [ISAPNP] Exclude DMAs for the autoconfiguration

            pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
                            Ranges are in pairs (I/O port base and size).

            pnp_reserve_mem=
                            [ISAPNP] Exclude memory regions for the
                            autoconfiguration.
                            Ranges are in pairs (memory base and size).

            ports=          [IP_VS_FTP] IPVS ftp helper module
                            Default is 21.
                            Up to 8 (IP_VS_APP_MAX_PORTS) ports
                            may be specified.
                            Format: <port>,<port>....

            powersave=off   [PPC] This option disables power saving features.
                            It specifically disables cpuidle and sets the
                            platform machine description specific power_save
                            function to NULL. On Idle the CPU just reduces
                            execution priority.

            ppc_strict_facility_enable
                            [PPC] This option catches any kernel floating point,
                            Altivec, VSX and SPE outside of regions specifically
                            allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
                            There is some performance impact when enabling this.

            ppc_tm=         [PPC]
                            Format: {"off"}
                            Disable Hardware Transactional Memory

            preempt=        [KNL]
                            Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC
                            none - Limited to cond_resched() calls
                            voluntary - Limited to cond_resched() and might_sleep() calls
                            full - Any section that isn't explicitly preempt disabled
                                   can be preempted anytime.

            print-fatal-signals=
                            [KNL] debug: print fatal signals

                            If enabled, warn about various signal handling
                            related application anomalies: too many signals,
                            too many POSIX.1 timers, fatal signals causing a
                            coredump - etc.

                            If you hit the warning due to signal overflow,
                            you might want to try "ulimit -i unlimited".

                            default: off.

            printk.always_kmsg_dump=
                            Trigger kmsg_dump for cases other than kernel oops or
                            panics
                            Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
                            default: disabled

            printk.console_no_auto_verbose=
                            Disable console loglevel raise on oops, panic
                            or lockdep-detected issues (only if lock debug is on).
                            With an exception to setups with low baudrate on
                            serial console, keeping this 0 is a good choice
                            in order to provide more debug information.
                            Format: <bool>
                            default: 0 (auto_verbose is enabled)

            printk.devkmsg={on,off,ratelimit}
                            Control writing to /dev/kmsg.
                            on - unlimited logging to /dev/kmsg from userspace
                            off - logging to /dev/kmsg disabled
                            ratelimit - ratelimit the logging
                            Default: ratelimit

            printk.time=    Show timing data prefixed to each printk message line
                            Format: <bool>  (1/Y/y=enable, 0/N/n=disable)

            processor.max_cstate=   [HW,ACPI]
                            Limit processor to maximum C-state
                            max_cstate=9 overrides any DMI blacklist limit.

            processor.nocst [HW,ACPI]
                            Ignore the _CST method to determine C-states,
                            instead using the legacy FADT method

            profile=        [KNL] Enable kernel profiling via /proc/profile
                            Format: [<profiletype>,]<number>
                            Param: <profiletype>: "schedule", "sleep", or "kvm"
                                    [defaults to kernel profiling]
                            Param: "schedule" - profile schedule points.
                            Param: "sleep" - profile D-state sleeping (millisecs).
                                    Requires CONFIG_SCHEDSTATS
                            Param: "kvm" - profile VM exits.
                            Param: <number> - step/bucket size as a power of 2 for
                                    statistical time based profiling.

            prompt_ramdisk= [RAM] [Deprecated]

            prot_virt=      [S390] enable hosting protected virtual machines
                            isolated from the hypervisor (if hardware supports
                            that).
                            Format: <bool>

            psi=            [KNL] Enable or disable pressure stall information
                            tracking.
                            Format: <bool>

            psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
                            probe for; one of (bare|imps|exps|lifebook|any).
            psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
                            per second.
            psmouse.resetafter=     [HW,MOUSE]
                            Try to reset the device after so many bad packets
                            (0 = never).
            psmouse.resolution=
                            [HW,MOUSE] Set desired mouse resolution, in dpi.
            psmouse.smartscroll=
                            [HW,MOUSE] Controls Logitech smartscroll autorepeat.
                            0 = disabled, 1 = enabled (default).

            pstore.backend= Specify the name of the pstore backend to use

            pt.             [PARIDE]
                            See Documentation/admin-guide/blockdev/paride.rst.

            pti=            [X86-64] Control Page Table Isolation of user and
                            kernel address spaces.  Disabling this feature
                            removes hardening, but improves performance of
                            system calls and interrupts.

                            on   - unconditionally enable
                            off  - unconditionally disable
                            auto - kernel detects whether your CPU model is
                                   vulnerable to issues that PTI mitigates

                            Not specifying this option is equivalent to pti=auto.

            nopti           [X86-64]
                            Equivalent to pti=off

            pty.legacy_count=
                            [KNL] Number of legacy pty's. Overwrites compiled-in
                            default number.

            quiet           [KNL] Disable most log messages

            r128=           [HW,DRM]

            raid=           [HW,RAID]
                            See Documentation/admin-guide/md.rst.

            ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
                            See Documentation/admin-guide/blockdev/ramdisk.rst.

            ramdisk_start=  [RAM] RAM disk image start address

            random.trust_cpu={on,off}
                            [KNL] Enable or disable trusting the use of the
                            CPU's random number generator (if available) to
                            fully seed the kernel's CRNG. Default is controlled
                            by CONFIG_RANDOM_TRUST_CPU.

            random.trust_bootloader={on,off}
                            [KNL] Enable or disable trusting the use of a
                            seed passed by the bootloader (if available) to
                            fully seed the kernel's CRNG. Default is controlled
                            by CONFIG_RANDOM_TRUST_BOOTLOADER.

            randomize_kstack_offset=
                            [KNL] Enable or disable kernel stack offset
                            randomization, which provides roughly 5 bits of
                            entropy, frustrating memory corruption attacks
                            that depend on stack address determinism or
                            cross-syscall address exposures. This is only
                            available on architectures that have defined
                            CONFIG_HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET.
                            Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
                            Default is CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT.

            ras=option[,option,...] [KNL] RAS-specific options

                    cec_disable     [X86]
                                    Disable the Correctable Errors Collector,
                                    see CONFIG_RAS_CEC help text.

            rcu_nocbs[=cpu-list]
                            [KNL] The optional argument is a cpu list,
                            as described above.

                            In kernels built with CONFIG_RCU_NOCB_CPU=y,
                            enable the no-callback CPU mode, which prevents
                            such CPUs' callbacks from being invoked in
                            softirq context.  Invocation of such CPUs' RCU
                            callbacks will instead be offloaded to "rcuox/N"
                            kthreads created for that purpose, where "x" is
                            "p" for RCU-preempt, "s" for RCU-sched, and "g"
                            for the kthreads that mediate grace periods; and
                            "N" is the CPU number. This reduces OS jitter on
                            the offloaded CPUs, which can be useful for HPC
                            and real-time workloads.  It can also improve
                            energy efficiency for asymmetric multiprocessors.

                            If a cpulist is passed as an argument, the specified
                            list of CPUs is set to no-callback mode from boot.

                            Otherwise, if the '=' sign and the cpulist
                            arguments are omitted, no CPU will be set to
                            no-callback mode from boot but the mode may be
                            toggled at runtime via cpusets.

            rcu_nocb_poll   [KNL]
                            Rather than requiring that offloaded CPUs
                            (specified by rcu_nocbs= above) explicitly
                            awaken the corresponding "rcuoN" kthreads,
                            make these kthreads poll for callbacks.
                            This improves the real-time response for the
                            offloaded CPUs by relieving them of the need to
                            wake up the corresponding kthread, but degrades
                            energy efficiency by requiring that the kthreads
                            periodically wake up to do the polling.

            rcutree.blimit= [KNL]
                            Set maximum number of finished RCU callbacks to
                            process in one batch.

            rcutree.dump_tree=      [KNL]
                            Dump the structure of the rcu_node combining tree
                            out at early boot.  This is used for diagnostic
                            purposes, to verify correct tree setup.

            rcutree.gp_cleanup_delay=       [KNL]
                            Set the number of jiffies to delay each step of
                            RCU grace-period cleanup.

            rcutree.gp_init_delay=  [KNL]
                            Set the number of jiffies to delay each step of
                            RCU grace-period initialization.

            rcutree.gp_preinit_delay=       [KNL]
                            Set the number of jiffies to delay each step of
                            RCU grace-period pre-initialization, that is,
                            the propagation of recent CPU-hotplug changes up
                            the rcu_node combining tree.

            rcutree.use_softirq=    [KNL]
                            If set to zero, move all RCU_SOFTIRQ processing to
                            per-CPU rcuc kthreads.  Defaults to a non-zero
                            value, meaning that RCU_SOFTIRQ is used by default.
                            Specify rcutree.use_softirq=0 to use rcuc kthreads.

                            But note that CONFIG_PREEMPT_RT=y kernels disable
                            this kernel boot parameter, forcibly setting it
                            to zero.

            rcutree.rcu_fanout_exact= [KNL]
                            Disable autobalancing of the rcu_node combining
                            tree.  This is used by rcutorture, and might
                            possibly be useful for architectures having high
                            cache-to-cache transfer latencies.

            rcutree.rcu_fanout_leaf= [KNL]
                            Change the number of CPUs assigned to each
                            leaf rcu_node structure.  Useful for very
                            large systems, which will choose the value 64,
                            and for NUMA systems with large remote-access
                            latencies, which will choose a value aligned
                            with the appropriate hardware boundaries.

            rcutree.rcu_min_cached_objs= [KNL]
                            Minimum number of objects which are cached and
                            maintained per one CPU. Object size is equal
                            to PAGE_SIZE. The cache allows to reduce the
                            pressure to page allocator, also it makes the
                            whole algorithm to behave better in low memory
                            condition.

            rcutree.rcu_delay_page_cache_fill_msec= [KNL]
                            Set the page-cache refill delay (in milliseconds)
                            in response to low-memory conditions.  The range
                            of permitted values is in the range 0:100000.

            rcutree.jiffies_till_first_fqs= [KNL]
                            Set delay from grace-period initialization to
                            first attempt to force quiescent states.
                            Units are jiffies, minimum value is zero,
                            and maximum value is HZ.

            rcutree.jiffies_till_next_fqs= [KNL]
                            Set delay between subsequent attempts to force
                            quiescent states.  Units are jiffies, minimum
                            value is one, and maximum value is HZ.

            rcutree.jiffies_till_sched_qs= [KNL]
                            Set required age in jiffies for a
                            given grace period before RCU starts
                            soliciting quiescent-state help from
                            rcu_note_context_switch() and cond_resched().
                            If not specified, the kernel will calculate
                            a value based on the most recent settings
                            of rcutree.jiffies_till_first_fqs
                            and rcutree.jiffies_till_next_fqs.
                            This calculated value may be viewed in
                            rcutree.jiffies_to_sched_qs.  Any attempt to set
                            rcutree.jiffies_to_sched_qs will be cheerfully
                            overwritten.

            rcutree.kthread_prio=    [KNL,BOOT]
                            Set the SCHED_FIFO priority of the RCU per-CPU
                            kthreads (rcuc/N). This value is also used for
                            the priority of the RCU boost threads (rcub/N)
                            and for the RCU grace-period kthreads (rcu_bh,
                            rcu_preempt, and rcu_sched). If RCU_BOOST is
                            set, valid values are 1-99 and the default is 1
                            (the least-favored priority).  Otherwise, when
                            RCU_BOOST is not set, valid values are 0-99 and
                            the default is zero (non-realtime operation).
                            When RCU_NOCB_CPU is set, also adjust the
                            priority of NOCB callback kthreads.

            rcutree.rcu_nocb_gp_stride= [KNL]
                            Set the number of NOCB callback kthreads in
                            each group, which defaults to the square root
                            of the number of CPUs.  Larger numbers reduce
                            the wakeup overhead on the global grace-period
                            kthread, but increases that same overhead on
                            each group's NOCB grace-period kthread.

            rcutree.qhimark= [KNL]
                            Set threshold of queued RCU callbacks beyond which
                            batch limiting is disabled.

            rcutree.qlowmark= [KNL]
                            Set threshold of queued RCU callbacks below which
                            batch limiting is re-enabled.

            rcutree.qovld= [KNL]
                            Set threshold of queued RCU callbacks beyond which
                            RCU's force-quiescent-state scan will aggressively
                            enlist help from cond_resched() and sched IPIs to
                            help CPUs more quickly reach quiescent states.
                            Set to less than zero to make this be set based
                            on rcutree.qhimark at boot time and to zero to
                            disable more aggressive help enlistment.

            rcutree.rcu_kick_kthreads= [KNL]
                            Cause the grace-period kthread to get an extra
                            wake_up() if it sleeps three times longer than
                            it should at force-quiescent-state time.
                            This wake_up() will be accompanied by a
                            WARN_ONCE() splat and an ftrace_dump().

            rcutree.rcu_unlock_delay= [KNL]
                            In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
                            this specifies an rcu_read_unlock()-time delay
                            in microseconds.  This defaults to zero.
                            Larger delays increase the probability of
                            catching RCU pointer leaks, that is, buggy use
                            of RCU-protected pointers after the relevant
                            rcu_read_unlock() has completed.

            rcutree.sysrq_rcu= [KNL]
                            Commandeer a sysrq key to dump out Tree RCU's
                            rcu_node tree with an eye towards determining
                            why a new grace period has not yet started.

            rcuscale.gp_async= [KNL]
                            Measure performance of asynchronous
                            grace-period primitives such as call_rcu().

            rcuscale.gp_async_max= [KNL]
                            Specify the maximum number of outstanding
                            callbacks per writer thread.  When a writer
                            thread exceeds this limit, it invokes the
                            corresponding flavor of rcu_barrier() to allow
                            previously posted callbacks to drain.

            rcuscale.gp_exp= [KNL]
                            Measure performance of expedited synchronous
                            grace-period primitives.

            rcuscale.holdoff= [KNL]
                            Set test-start holdoff period.  The purpose of
                            this parameter is to delay the start of the
                            test until boot completes in order to avoid
                            interference.

            rcuscale.kfree_rcu_test= [KNL]
                            Set to measure performance of kfree_rcu() flooding.

            rcuscale.kfree_rcu_test_double= [KNL]
                            Test the double-argument variant of kfree_rcu().
                            If this parameter has the same value as
                            rcuscale.kfree_rcu_test_single, both the single-
                            and double-argument variants are tested.

            rcuscale.kfree_rcu_test_single= [KNL]
                            Test the single-argument variant of kfree_rcu().
                            If this parameter has the same value as
                            rcuscale.kfree_rcu_test_double, both the single-
                            and double-argument variants are tested.

            rcuscale.kfree_nthreads= [KNL]
                            The number of threads running loops of kfree_rcu().

            rcuscale.kfree_alloc_num= [KNL]
                            Number of allocations and frees done in an iteration.

            rcuscale.kfree_loops= [KNL]
                            Number of loops doing rcuscale.kfree_alloc_num number
                            of allocations and frees.

            rcuscale.nreaders= [KNL]
                            Set number of RCU readers.  The value -1 selects
                            N, where N is the number of CPUs.  A value
                            "n" less than -1 selects N-n+1, where N is again
                            the number of CPUs.  For example, -2 selects N
                            (the number of CPUs), -3 selects N+1, and so on.
                            A value of "n" less than or equal to -N selects
                            a single reader.

            rcuscale.nwriters= [KNL]
                            Set number of RCU writers.  The values operate
                            the same as for rcuscale.nreaders.
                            N, where N is the number of CPUs

            rcuscale.perf_type= [KNL]
                            Specify the RCU implementation to test.

            rcuscale.shutdown= [KNL]
                            Shut the system down after performance tests
                            complete.  This is useful for hands-off automated
                            testing.

            rcuscale.verbose= [KNL]
                            Enable additional printk() statements.

            rcuscale.writer_holdoff= [KNL]
                            Write-side holdoff between grace periods,
                            in microseconds.  The default of zero says
                            no holdoff.

            rcutorture.fqs_duration= [KNL]
                            Set duration of force_quiescent_state bursts
                            in microseconds.

            rcutorture.fqs_holdoff= [KNL]
                            Set holdoff time within force_quiescent_state bursts
                            in microseconds.

            rcutorture.fqs_stutter= [KNL]
                            Set wait time between force_quiescent_state bursts
                            in seconds.

            rcutorture.fwd_progress= [KNL]
                            Specifies the number of kthreads to be used
                            for  RCU grace-period forward-progress testing
                            for the types of RCU supporting this notion.
                            Defaults to 1 kthread, values less than zero or
                            greater than the number of CPUs cause the number
                            of CPUs to be used.

            rcutorture.fwd_progress_div= [KNL]
                            Specify the fraction of a CPU-stall-warning
                            period to do tight-loop forward-progress testing.

            rcutorture.fwd_progress_holdoff= [KNL]
                            Number of seconds to wait between successive
                            forward-progress tests.

            rcutorture.fwd_progress_need_resched= [KNL]
                            Enclose cond_resched() calls within checks for
                            need_resched() during tight-loop forward-progress
                            testing.

            rcutorture.gp_cond= [KNL]
                            Use conditional/asynchronous update-side
                            primitives, if available.

            rcutorture.gp_exp= [KNL]
                            Use expedited update-side primitives, if available.

            rcutorture.gp_normal= [KNL]
                            Use normal (non-expedited) asynchronous
                            update-side primitives, if available.

            rcutorture.gp_sync= [KNL]
                            Use normal (non-expedited) synchronous
                            update-side primitives, if available.  If all
                            of rcutorture.gp_cond=, rcutorture.gp_exp=,
                            rcutorture.gp_normal=, and rcutorture.gp_sync=
                            are zero, rcutorture acts as if is interpreted
                            they are all non-zero.

            rcutorture.irqreader= [KNL]
                            Run RCU readers from irq handlers, or, more
                            accurately, from a timer handler.  Not all RCU
                            flavors take kindly to this sort of thing.

            rcutorture.leakpointer= [KNL]
                            Leak an RCU-protected pointer out of the reader.
                            This can of course result in splats, and is
                            intended to test the ability of things like
                            CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect
                            such leaks.

            rcutorture.n_barrier_cbs= [KNL]
                            Set callbacks/threads for rcu_barrier() testing.

            rcutorture.nfakewriters= [KNL]
                            Set number of concurrent RCU writers.  These just
                            stress RCU, they don't participate in the actual
                            test, hence the "fake".

            rcutorture.nocbs_nthreads= [KNL]
                            Set number of RCU callback-offload togglers.
                            Zero (the default) disables toggling.

            rcutorture.nocbs_toggle= [KNL]
                            Set the delay in milliseconds between successive
                            callback-offload toggling attempts.

            rcutorture.nreaders= [KNL]
                            Set number of RCU readers.  The value -1 selects
                            N-1, where N is the number of CPUs.  A value
                            "n" less than -1 selects N-n-2, where N is again
                            the number of CPUs.  For example, -2 selects N
                            (the number of CPUs), -3 selects N+1, and so on.

            rcutorture.object_debug= [KNL]
                            Enable debug-object double-call_rcu() testing.

            rcutorture.onoff_holdoff= [KNL]
                            Set time (s) after boot for CPU-hotplug testing.

            rcutorture.onoff_interval= [KNL]
                            Set time (jiffies) between CPU-hotplug operations,
                            or zero to disable CPU-hotplug testing.

            rcutorture.read_exit= [KNL]
                            Set the number of read-then-exit kthreads used
                            to test the interaction of RCU updaters and
                            task-exit processing.

            rcutorture.read_exit_burst= [KNL]
                            The number of times in a given read-then-exit
                            episode that a set of read-then-exit kthreads
                            is spawned.

            rcutorture.read_exit_delay= [KNL]
                            The delay, in seconds, between successive
                            read-then-exit testing episodes.

            rcutorture.shuffle_interval= [KNL]
                            Set task-shuffle interval (s).  Shuffling tasks
                            allows some CPUs to go into dyntick-idle mode
                            during the rcutorture test.

            rcutorture.shutdown_secs= [KNL]
                            Set time (s) after boot system shutdown.  This
                            is useful for hands-off automated testing.

            rcutorture.stall_cpu= [KNL]
                            Duration of CPU stall (s) to test RCU CPU stall
                            warnings, zero to disable.

            rcutorture.stall_cpu_block= [KNL]
                            Sleep while stalling if set.  This will result
                            in warnings from preemptible RCU in addition
                            to any other stall-related activity.

            rcutorture.stall_cpu_holdoff= [KNL]
                            Time to wait (s) after boot before inducing stall.

            rcutorture.stall_cpu_irqsoff= [KNL]
                            Disable interrupts while stalling if set.

            rcutorture.stall_gp_kthread= [KNL]
                            Duration (s) of forced sleep within RCU
                            grace-period kthread to test RCU CPU stall
                            warnings, zero to disable.  If both stall_cpu
                            and stall_gp_kthread are specified, the
                            kthread is starved first, then the CPU.

            rcutorture.stat_interval= [KNL]
                            Time (s) between statistics printk()s.

            rcutorture.stutter= [KNL]
                            Time (s) to stutter testing, for example, specifying
                            five seconds causes the test to run for five seconds,
                            wait for five seconds, and so on.  This tests RCU's
                            ability to transition abruptly to and from idle.

            rcutorture.test_boost= [KNL]
                            Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
                            "Maybe" means test if the RCU implementation
                            under test support RCU priority boosting.

            rcutorture.test_boost_duration= [KNL]
                            Duration (s) of each individual boost test.

            rcutorture.test_boost_interval= [KNL]
                            Interval (s) between each boost test.

            rcutorture.test_no_idle_hz= [KNL]
                            Test RCU's dyntick-idle handling.  See also the
                            rcutorture.shuffle_interval parameter.

            rcutorture.torture_type= [KNL]
                            Specify the RCU implementation to test.

            rcutorture.verbose= [KNL]
                            Enable additional printk() statements.

            rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
                            Dump ftrace buffer after reporting RCU CPU
                            stall warning.

            rcupdate.rcu_cpu_stall_suppress= [KNL]
                            Suppress RCU CPU stall warning messages.

            rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
                            Suppress RCU CPU stall warning messages and
                            rcutorture writer stall warnings that occur
                            during early boot, that is, during the time
                            before the init task is spawned.

            rcupdate.rcu_cpu_stall_timeout= [KNL]
                            Set timeout for RCU CPU stall warning messages.

            rcupdate.rcu_expedited= [KNL]
                            Use expedited grace-period primitives, for
                            example, synchronize_rcu_expedited() instead
                            of synchronize_rcu().  This reduces latency,
                            but can increase CPU utilization, degrade
                            real-time latency, and degrade energy efficiency.
                            No effect on CONFIG_TINY_RCU kernels.

            rcupdate.rcu_normal= [KNL]
                            Use only normal grace-period primitives,
                            for example, synchronize_rcu() instead of
                            synchronize_rcu_expedited().  This improves
                            real-time latency, CPU utilization, and
                            energy efficiency, but can expose users to
                            increased grace-period latency.  This parameter
                            overrides rcupdate.rcu_expedited.  No effect on
                            CONFIG_TINY_RCU kernels.

            rcupdate.rcu_normal_after_boot= [KNL]
                            Once boot has completed (that is, after
                            rcu_end_inkernel_boot() has been invoked), use
                            only normal grace-period primitives.  No effect
                            on CONFIG_TINY_RCU kernels.

                            But note that CONFIG_PREEMPT_RT=y kernels enables
                            this kernel boot parameter, forcibly setting
                            it to the value one, that is, converting any
                            post-boot attempt at an expedited RCU grace
                            period to instead use normal non-expedited
                            grace-period processing.

            rcupdate.rcu_task_collapse_lim= [KNL]
                            Set the maximum number of callbacks present
                            at the beginning of a grace period that allows
                            the RCU Tasks flavors to collapse back to using
                            a single callback queue.  This switching only
                            occurs when rcupdate.rcu_task_enqueue_lim is
                            set to the default value of -1.

            rcupdate.rcu_task_contend_lim= [KNL]
                            Set the minimum number of callback-queuing-time
                            lock-contention events per jiffy required to
                            cause the RCU Tasks flavors to switch to per-CPU
                            callback queuing.  This switching only occurs
                            when rcupdate.rcu_task_enqueue_lim is set to
                            the default value of -1.

            rcupdate.rcu_task_enqueue_lim= [KNL]
                            Set the number of callback queues to use for the
                            RCU Tasks family of RCU flavors.  The default
                            of -1 allows this to be automatically (and
                            dynamically) adjusted.  This parameter is intended
                            for use in testing.

            rcupdate.rcu_task_ipi_delay= [KNL]
                            Set time in jiffies during which RCU tasks will
                            avoid sending IPIs, starting with the beginning
                            of a given grace period.  Setting a large
                            number avoids disturbing real-time workloads,
                            but lengthens grace periods.

            rcupdate.rcu_task_stall_timeout= [KNL]
                            Set timeout in jiffies for RCU task stall warning
                            messages.  Disable with a value less than or equal
                            to zero.

            rcupdate.rcu_self_test= [KNL]
                            Run the RCU early boot self tests

            rdinit=         [KNL]
                            Format: <full_path>
                            Run specified binary instead of /init from the ramdisk,
                            used for early userspace startup. See initrd.

            rdrand=         [X86]
                            force - Override the decision by the kernel to hide the
                                    advertisement of RDRAND support (this affects
                                    certain AMD processors because of buggy BIOS
                                    support, specifically around the suspend/resume
                                    path).

            rdt=            [HW,X86,RDT]
                            Turn on/off individual RDT features. List is:
                            cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
                            mba.
                            E.g. to turn on cmt and turn off mba use:
                                    rdt=cmt,!mba

            reboot=         [KNL]
                            Format (x86 or x86_64):
                                    [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] | d[efault] \
                                    [[,]s[mp]#### \
                                    [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
                                    [[,]f[orce]
                            Where reboot_mode is one of warm (soft) or cold (hard) or gpio
                                            (prefix with 'panic_' to set mode for panic
                                            reboot only),
                                  reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
                                  reboot_force is either force or not specified,
                                  reboot_cpu is s[mp]#### with #### being the processor
                                            to be used for rebooting.

            refscale.holdoff= [KNL]
                            Set test-start holdoff period.  The purpose of
                            this parameter is to delay the start of the
                            test until boot completes in order to avoid
                            interference.

            refscale.loops= [KNL]
                            Set the number of loops over the synchronization
                            primitive under test.  Increasing this number
                            reduces noise due to loop start/end overhead,
                            but the default has already reduced the per-pass
                            noise to a handful of picoseconds on ca. 2020
                            x86 laptops.

            refscale.nreaders= [KNL]
                            Set number of readers.  The default value of -1
                            selects N, where N is roughly 75% of the number
                            of CPUs.  A value of zero is an interesting choice.

            refscale.nruns= [KNL]
                            Set number of runs, each of which is dumped onto
                            the console log.

            refscale.readdelay= [KNL]
                            Set the read-side critical-section duration,
                            measured in microseconds.

            refscale.scale_type= [KNL]
                            Specify the read-protection implementation to test.

            refscale.shutdown= [KNL]
                            Shut down the system at the end of the performance
                            test.  This defaults to 1 (shut it down) when
                            refscale is built into the kernel and to 0 (leave
                            it running) when refscale is built as a module.

            refscale.verbose= [KNL]
                            Enable additional printk() statements.

            refscale.verbose_batched= [KNL]
                            Batch the additional printk() statements.  If zero
                            (the default) or negative, print everything.  Otherwise,
                            print every Nth verbose statement, where N is the value
                            specified.

            relax_domain_level=
                            [KNL, SMP] Set scheduler's default relax_domain_level.
                            See Documentation/admin-guide/cgroup-v1/cpusets.rst.

            reserve=        [KNL,BUGS] Force kernel to ignore I/O ports or memory
                            Format: <base1>,<size1>[,<base2>,<size2>,...]
                            Reserve I/O ports or memory so the kernel won't use
                            them.  If <base> is less than 0x10000, the region
                            is assumed to be I/O ports; otherwise it is memory.

            reservetop=     [X86-32]
                            Format: nn[KMG]
                            Reserves a hole at the top of the kernel virtual
                            address space.

            reset_devices   [KNL] Force drivers to reset the underlying device
                            during initialization.

            resume=         [SWSUSP]
                            Specify the partition device for software suspend
                            Format:
                            {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}

            resume_offset=  [SWSUSP]
                            Specify the offset from the beginning of the partition
                            given by "resume=" at which the swap header is located,
                            in <PAGE_SIZE> units (needed only for swap files).
                            See  Documentation/power/swsusp-and-swap-files.rst

            resumedelay=    [HIBERNATION] Delay (in seconds) to pause before attempting to
                            read the resume files

            resumewait      [HIBERNATION] Wait (indefinitely) for resume device to show up.
                            Useful for devices that are detected asynchronously
                            (e.g. USB and MMC devices).

            hibernate=      [HIBERNATION]
                    noresume        Don't check if there's a hibernation image
                                    present during boot.
                    nocompress      Don't compress/decompress hibernation images.
                    no              Disable hibernation and resume.
                    protect_image   Turn on image protection during restoration
                                    (that will set all pages holding image data
                                    during restoration read-only).

            retain_initrd   [RAM] Keep initrd memory after extraction

            rfkill.default_state=
                    0       "airplane mode".  All wifi, bluetooth, wimax, gps, fm,
                            etc. communication is blocked by default.
                    1       Unblocked.

            rfkill.master_switch_mode=
                    0       The "airplane mode" button does nothing.
                    1       The "airplane mode" button toggles between everything
                            blocked and the previous configuration.
                    2       The "airplane mode" button toggles between everything
                            blocked and everything unblocked.

            rhash_entries=  [KNL,NET]
                            Set number of hash buckets for route cache

            ring3mwait=disable
                            [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
                            CPUs.

            ro              [KNL] Mount root device read-only on boot

            rodata=         [KNL]
                    on      Mark read-only kernel memory as read-only (default).
                    off     Leave read-only kernel memory writable for debugging.

            rockchip.usb_uart
                            Enable the uart passthrough on the designated usb port
                            on Rockchip SoCs. When active, the signals of the
                            debug-uart get routed to the D+ and D- pins of the usb
                            port and the regular usb controller gets disabled.

            root=           [KNL] Root filesystem
                            See name_to_dev_t comment in init/do_mounts.c.

            rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
                            mount the root filesystem

            rootflags=      [KNL] Set root filesystem mount option string

            rootfstype=     [KNL] Set root filesystem type

            rootwait        [KNL] Wait (indefinitely) for root device to show up.
                            Useful for devices that are detected asynchronously
                            (e.g. USB and MMC devices).

            rproc_mem=nn[KMG][@address]
                            [KNL,ARM,CMA] Remoteproc physical memory block.
                            Memory area to be used by remote processor image,
                            managed by CMA.

            rw              [KNL] Mount root device read-write on boot

            S               [KNL] Run init in single mode

            s390_iommu=     [HW,S390]
                            Set s390 IOTLB flushing mode
                    strict
                            With strict flushing every unmap operation will result in
                            an IOTLB flush. Default is lazy flushing before reuse,
                            which is faster.

            s390_iommu_aperture=    [KNL,S390]
                            Specifies the size of the per device DMA address space
                            accessible through the DMA and IOMMU APIs as a decimal
                            factor of the size of main memory.
                            The default is 1 meaning that one can concurrently use
                            as many DMA addresses as physical memory is installed,
                            if supported by hardware, and thus map all of memory
                            once. With a value of 2 one can map all of memory twice
                            and so on. As a special case a factor of 0 imposes no
                            restrictions other than those given by hardware at the
                            cost of significant additional memory use for tables.

            sa1100ir        [NET]
                            See drivers/net/irda/sa1100_ir.c.

            sched_verbose   [KNL] Enables verbose scheduler debug messages.

            schedstats=     [KNL,X86] Enable or disable scheduled statistics.
                            Allowed values are enable and disable. This feature
                            incurs a small amount of overhead in the scheduler
                            but is useful for debugging and performance tuning.

            sched_thermal_decay_shift=
                            [KNL, SMP] Set a decay shift for scheduler thermal
                            pressure signal. Thermal pressure signal follows the
                            default decay period of other scheduler pelt
                            signals(usually 32 ms but configurable). Setting
                            sched_thermal_decay_shift will left shift the decay
                            period for the thermal pressure signal by the shift
                            value.
                            i.e. with the default pelt decay period of 32 ms
                            sched_thermal_decay_shift   thermal pressure decay pr
                                    1                       64 ms
                                    2                       128 ms
                            and so on.
                            Format: integer between 0 and 10
                            Default is 0.

            scftorture.holdoff= [KNL]
                            Number of seconds to hold off before starting
                            test.  Defaults to zero for module insertion and
                            to 10 seconds for built-in smp_call_function()
                            tests.

            scftorture.longwait= [KNL]
                            Request ridiculously long waits randomly selected
                            up to the chosen limit in seconds.  Zero (the
                            default) disables this feature.  Please note
                            that requesting even small non-zero numbers of
                            seconds can result in RCU CPU stall warnings,
                            softlockup complaints, and so on.

            scftorture.nthreads= [KNL]
                            Number of kthreads to spawn to invoke the
                            smp_call_function() family of functions.
                            The default of -1 specifies a number of kthreads
                            equal to the number of CPUs.

            scftorture.onoff_holdoff= [KNL]
                            Number seconds to wait after the start of the
                            test before initiating CPU-hotplug operations.

            scftorture.onoff_interval= [KNL]
                            Number seconds to wait between successive
                            CPU-hotplug operations.  Specifying zero (which
                            is the default) disables CPU-hotplug operations.

            scftorture.shutdown_secs= [KNL]
                            The number of seconds following the start of the
                            test after which to shut down the system.  The
                            default of zero avoids shutting down the system.
                            Non-zero values are useful for automated tests.

            scftorture.stat_interval= [KNL]
                            The number of seconds between outputting the
                            current test statistics to the console.  A value
                            of zero disables statistics output.

            scftorture.stutter_cpus= [KNL]
                            The number of jiffies to wait between each change
                            to the set of CPUs under test.

            scftorture.use_cpus_read_lock= [KNL]
                            Use use_cpus_read_lock() instead of the default
                            preempt_disable() to disable CPU hotplug
                            while invoking one of the smp_call_function*()
                            functions.

            scftorture.verbose= [KNL]
                            Enable additional printk() statements.

            scftorture.weight_single= [KNL]
                            The probability weighting to use for the
                            smp_call_function_single() function with a zero
                            "wait" parameter.  A value of -1 selects the
                            default if all other weights are -1.  However,
                            if at least one weight has some other value, a
                            value of -1 will instead select a weight of zero.

            scftorture.weight_single_wait= [KNL]
                            The probability weighting to use for the
                            smp_call_function_single() function with a
                            non-zero "wait" parameter.  See weight_single.

            scftorture.weight_many= [KNL]
                            The probability weighting to use for the
                            smp_call_function_many() function with a zero
                            "wait" parameter.  See weight_single.
                            Note well that setting a high probability for
                            this weighting can place serious IPI load
                            on the system.

            scftorture.weight_many_wait= [KNL]
                            The probability weighting to use for the
                            smp_call_function_many() function with a
                            non-zero "wait" parameter.  See weight_single
                            and weight_many.

            scftorture.weight_all= [KNL]
                            The probability weighting to use for the
                            smp_call_function_all() function with a zero
                            "wait" parameter.  See weight_single and
                            weight_many.

            scftorture.weight_all_wait= [KNL]
                            The probability weighting to use for the
                            smp_call_function_all() function with a
                            non-zero "wait" parameter.  See weight_single
                            and weight_many.

            skew_tick=      [KNL] Offset the periodic timer tick per cpu to mitigate
                            xtime_lock contention on larger systems, and/or RCU lock
                            contention on all systems with CONFIG_MAXSMP set.
                            Format: { "0" | "1" }
                            0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
                            1 -- enable.
                            Note: increases power consumption, thus should only be
                            enabled if running jitter sensitive (HPC/RT) workloads.

            security=       [SECURITY] Choose a legacy "major" security module to
                            enable at boot. This has been deprecated by the
                            "lsm=" parameter.

            selinux=        [SELINUX] Disable or enable SELinux at boot time.
                            Format: { "0" | "1" }
                            See security/selinux/Kconfig help text.
                            0 -- disable.
                            1 -- enable.
                            Default value is 1.

            apparmor=       [APPARMOR] Disable or enable AppArmor at boot time
                            Format: { "0" | "1" }
                            See security/apparmor/Kconfig help text
                            0 -- disable.
                            1 -- enable.
                            Default value is set via kernel config option.

            serialnumber    [BUGS=X86-32]

            shapers=        [NET]
                            Maximal number of shapers.

            simeth=         [IA-64]
            simscsi=

            slram=          [HW,MTD]

            slab_merge      [MM]
                            Enable merging of slabs with similar size when the
                            kernel is built without CONFIG_SLAB_MERGE_DEFAULT.

            slab_nomerge    [MM]
                            Disable merging of slabs with similar size. May be
                            necessary if there is some reason to distinguish
                            allocs to different slabs, especially in hardened
                            environments where the risk of heap overflows and
                            layout control by attackers can usually be
                            frustrated by disabling merging. This will reduce
                            most of the exposure of a heap attack to a single
                            cache (risks via metadata attacks are mostly
                            unchanged). Debug options disable merging on their
                            own.
                            For more information see Documentation/vm/slub.rst.

            slab_max_order= [MM, SLAB]
                            Determines the maximum allowed order for slabs.
                            A high setting may cause OOMs due to memory
                            fragmentation.  Defaults to 1 for systems with
                            more than 32MB of RAM, 0 otherwise.

            slub_debug[=options[,slabs][;[options[,slabs]]...]      [MM, SLUB]
                            Enabling slub_debug allows one to determine the
                            culprit if slab objects become corrupted. Enabling
                            slub_debug can create guard zones around objects and
                            may poison objects when not in use. Also tracks the
                            last alloc / free. For more information see
                            Documentation/vm/slub.rst.

            slub_max_order= [MM, SLUB]
                            Determines the maximum allowed order for slabs.
                            A high setting may cause OOMs due to memory
                            fragmentation. For more information see
                            Documentation/vm/slub.rst.

            slub_min_objects=       [MM, SLUB]
                            The minimum number of objects per slab. SLUB will
                            increase the slab order up to slub_max_order to
                            generate a sufficiently large slab able to contain
                            the number of objects indicated. The higher the number
                            of objects the smaller the overhead of tracking slabs
                            and the less frequently locks need to be acquired.
                            For more information see Documentation/vm/slub.rst.

            slub_min_order= [MM, SLUB]
                            Determines the minimum page order for slabs. Must be
                            lower than slub_max_order.
                            For more information see Documentation/vm/slub.rst.

            slub_merge      [MM, SLUB]
                            Same with slab_merge.

            slub_nomerge    [MM, SLUB]
                            Same with slab_nomerge. This is supported for legacy.
                            See slab_nomerge for more information.

            smart2=         [HW]
                            Format: <io1>[,<io2>[,...,<io8>]]

            smsc-ircc2.nopnp        [HW] Don't use PNP to discover SMC devices
            smsc-ircc2.ircc_cfg=    [HW] Device configuration I/O port
            smsc-ircc2.ircc_sir=    [HW] SIR base I/O port
            smsc-ircc2.ircc_fir=    [HW] FIR base I/O port
            smsc-ircc2.ircc_irq=    [HW] IRQ line
            smsc-ircc2.ircc_dma=    [HW] DMA channel
            smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
                                    0: Toshiba Satellite 1800 (GP data pin select)
                                    1: Fast pin select (default)
                                    2: ATC IRMode

            smt             [KNL,S390] Set the maximum number of threads (logical
                            CPUs) to use per physical CPU on systems capable of
                            symmetric multithreading (SMT). Will be capped to the
                            actual hardware limit.
                            Format: <integer>
                            Default: -1 (no limit)

            softlockup_panic=
                            [KNL] Should the soft-lockup detector generate panics.
                            Format: 0 | 1

                            A value of 1 instructs the soft-lockup detector
                            to panic the machine when a soft-lockup occurs. It is
                            also controlled by the kernel.softlockup_panic sysctl
                            and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
                            respective build-time switch to that functionality.

            softlockup_all_cpu_backtrace=
                            [KNL] Should the soft-lockup detector generate
                            backtraces on all cpus.
                            Format: 0 | 1

            sonypi.*=       [HW] Sony Programmable I/O Control Device driver
                            See Documentation/admin-guide/laptops/sonypi.rst

            spectre_v2=     [X86] Control mitigation of Spectre variant 2
                            (indirect branch speculation) vulnerability.
                            The default operation protects the kernel from
                            user space attacks.

                            on   - unconditionally enable, implies
                                   spectre_v2_user=on
                            off  - unconditionally disable, implies
                                   spectre_v2_user=off
                            auto - kernel detects whether your CPU model is
                                   vulnerable

                            Selecting 'on' will, and 'auto' may, choose a
                            mitigation method at run time according to the
                            CPU, the available microcode, the setting of the
                            CONFIG_RETPOLINE configuration option, and the
                            compiler with which the kernel was built.

                            Selecting 'on' will also enable the mitigation
                            against user space to user space task attacks.

                            Selecting 'off' will disable both the kernel and
                            the user space protections.

                            Specific mitigations can also be selected manually:

                            retpoline         - replace indirect branches
                            retpoline,generic - Retpolines
                            retpoline,lfence  - LFENCE; indirect branch
                            retpoline,amd     - alias for retpoline,lfence
                            eibrs             - enhanced IBRS
                            eibrs,retpoline   - enhanced IBRS + Retpolines
                            eibrs,lfence      - enhanced IBRS + LFENCE

                            Not specifying this option is equivalent to
                            spectre_v2=auto.

            spectre_v2_user=
                            [X86] Control mitigation of Spectre variant 2
                            (indirect branch speculation) vulnerability between
                            user space tasks

                            on      - Unconditionally enable mitigations. Is
                                      enforced by spectre_v2=on

                            off     - Unconditionally disable mitigations. Is
                                      enforced by spectre_v2=off

                            prctl   - Indirect branch speculation is enabled,
                                      but mitigation can be enabled via prctl
                                      per thread.  The mitigation control state
                                      is inherited on fork.

                            prctl,ibpb
                                    - Like "prctl" above, but only STIBP is
                                      controlled per thread. IBPB is issued
                                      always when switching between different user
                                      space processes.

                            seccomp
                                    - Same as "prctl" above, but all seccomp
                                      threads will enable the mitigation unless
                                      they explicitly opt out.

                            seccomp,ibpb
                                    - Like "seccomp" above, but only STIBP is
                                      controlled per thread. IBPB is issued
                                      always when switching between different
                                      user space processes.

                            auto    - Kernel selects the mitigation depending on
                                      the available CPU features and vulnerability.

                            Default mitigation: "prctl"

                            Not specifying this option is equivalent to
                            spectre_v2_user=auto.

            spec_store_bypass_disable=
                            [HW] Control Speculative Store Bypass (SSB) Disable mitigation
                            (Speculative Store Bypass vulnerability)

                            Certain CPUs are vulnerable to an exploit against a
                            a common industry wide performance optimization known
                            as "Speculative Store Bypass" in which recent stores
                            to the same memory location may not be observed by
                            later loads during speculative execution. The idea
                            is that such stores are unlikely and that they can
                            be detected prior to instruction retirement at the
                            end of a particular speculation execution window.

                            In vulnerable processors, the speculatively forwarded
                            store can be used in a cache side channel attack, for
                            example to read memory to which the attacker does not
                            directly have access (e.g. inside sandboxed code).

                            This parameter controls whether the Speculative Store
                            Bypass optimization is used.

                            On x86 the options are:

                            on      - Unconditionally disable Speculative Store Bypass
                            off     - Unconditionally enable Speculative Store Bypass
                            auto    - Kernel detects whether the CPU model contains an
                                      implementation of Speculative Store Bypass and
                                      picks the most appropriate mitigation. If the
                                      CPU is not vulnerable, "off" is selected. If the
                                      CPU is vulnerable the default mitigation is
                                      architecture and Kconfig dependent. See below.
                            prctl   - Control Speculative Store Bypass per thread
                                      via prctl. Speculative Store Bypass is enabled
                                      for a process by default. The state of the control
                                      is inherited on fork.
                            seccomp - Same as "prctl" above, but all seccomp threads
                                      will disable SSB unless they explicitly opt out.

                            Default mitigations:
                            X86:    "prctl"

                            On powerpc the options are:

                            on,auto - On Power8 and Power9 insert a store-forwarding
                                      barrier on kernel entry and exit. On Power7
                                      perform a software flush on kernel entry and
                                      exit.
                            off     - No action.

                            Not specifying this option is equivalent to
                            spec_store_bypass_disable=auto.

            spia_io_base=   [HW,MTD]
            spia_fio_base=
            spia_pedr=
            spia_peddr=

            split_lock_detect=
                            [X86] Enable split lock detection or bus lock detection

                            When enabled (and if hardware support is present), atomic
                            instructions that access data across cache line
                            boundaries will result in an alignment check exception
                            for split lock detection or a debug exception for
                            bus lock detection.

                            off     - not enabled

                            warn    - the kernel will emit rate-limited warnings
                                      about applications triggering the #AC
                                      exception or the #DB exception. This mode is
                                      the default on CPUs that support split lock
                                      detection or bus lock detection. Default
                                      behavior is by #AC if both features are
                                      enabled in hardware.

                            fatal   - the kernel will send SIGBUS to applications
                                      that trigger the #AC exception or the #DB
                                      exception. Default behavior is by #AC if
                                      both features are enabled in hardware.

                            ratelimit:N -
                                      Set system wide rate limit to N bus locks
                                      per second for bus lock detection.
                                      0 < N <= 1000.

                                      N/A for split lock detection.

                            If an #AC exception is hit in the kernel or in
                            firmware (i.e. not while executing in user mode)
                            the kernel will oops in either "warn" or "fatal"
                            mode.

                            #DB exception for bus lock is triggered only when
                            CPL > 0.

            srbds=          [X86,INTEL]
                            Control the Special Register Buffer Data Sampling
                            (SRBDS) mitigation.

                            Certain CPUs are vulnerable to an MDS-like
                            exploit which can leak bits from the random
                            number generator.

                            By default, this issue is mitigated by
                            microcode.  However, the microcode fix can cause
                            the RDRAND and RDSEED instructions to become
                            much slower.  Among other effects, this will
                            result in reduced throughput from /dev/urandom.

                            The microcode mitigation can be disabled with
                            the following option:

                            off:    Disable mitigation and remove
                                    performance impact to RDRAND and RDSEED

            srcutree.counter_wrap_check [KNL]
                            Specifies how frequently to check for
                            grace-period sequence counter wrap for the
                            srcu_data structure's ->srcu_gp_seq_needed field.
                            The greater the number of bits set in this kernel
                            parameter, the less frequently counter wrap will
                            be checked for.  Note that the bottom two bits
                            are ignored.

            srcutree.exp_holdoff [KNL]
                            Specifies how many nanoseconds must elapse
                            since the end of the last SRCU grace period for
                            a given srcu_struct until the next normal SRCU
                            grace period will be considered for automatic
                            expediting.  Set to zero to disable automatic
                            expediting.

            ssbd=           [ARM64,HW]
                            Speculative Store Bypass Disable control

                            On CPUs that are vulnerable to the Speculative
                            Store Bypass vulnerability and offer a
                            firmware based mitigation, this parameter
                            indicates how the mitigation should be used:

                            force-on:  Unconditionally enable mitigation for
                                       for both kernel and userspace
                            force-off: Unconditionally disable mitigation for
                                       for both kernel and userspace
                            kernel:    Always enable mitigation in the
                                       kernel, and offer a prctl interface
                                       to allow userspace to register its
                                       interest in being mitigated too.

            stack_guard_gap=        [MM]
                            override the default stack gap protection. The value
                            is in page units and it defines how many pages prior
                            to (for stacks growing down) resp. after (for stacks
                            growing up) the main stack are reserved for no other
                            mapping. Default value is 256 pages.

            stack_depot_disable= [KNL]
                            Setting this to true through kernel command line will
                            disable the stack depot thereby saving the static memory
                            consumed by the stack hash table. By default this is set
                            to false.

            stacktrace      [FTRACE]
                            Enabled the stack tracer on boot up.

            stacktrace_filter=[function-list]
                            [FTRACE] Limit the functions that the stack tracer
                            will trace at boot up. function-list is a comma-separated
                            list of functions. This list can be changed at run
                            time by the stack_trace_filter file in the debugfs
                            tracing directory. Note, this enables stack tracing
                            and the stacktrace above is not needed.

            sti=            [PARISC,HW]
                            Format: <num>
                            Set the STI (builtin display/keyboard on the HP-PARISC
                            machines) console (graphic card) which should be used
                            as the initial boot-console.
                            See also comment in drivers/video/console/sticore.c.

            sti_font=       [HW]
                            See comment in drivers/video/console/sticore.c.

            stifb=          [HW]
                            Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]

            strict_sas_size=
                            [X86]
                            Format: <bool>
                            Enable or disable strict sigaltstack size checks
                            against the required signal frame size which
                            depends on the supported FPU features. This can
                            be used to filter out binaries which have
                            not yet been made aware of AT_MINSIGSTKSZ.

            sunrpc.min_resvport=
            sunrpc.max_resvport=
                            [NFS,SUNRPC]
                            SunRPC servers often require that client requests
                            originate from a privileged port (i.e. a port in the
                            range 0 < portnr < 1024).
                            An administrator who wishes to reserve some of these
                            ports for other uses may adjust the range that the
                            kernel's sunrpc client considers to be privileged
                            using these two parameters to set the minimum and
                            maximum port values.

            sunrpc.svc_rpc_per_connection_limit=
                            [NFS,SUNRPC]
                            Limit the number of requests that the server will
                            process in parallel from a single connection.
                            The default value is 0 (no limit).

            sunrpc.pool_mode=
                            [NFS]
                            Control how the NFS server code allocates CPUs to
                            service thread pools.  Depending on how many NICs
                            you have and where their interrupts are bound, this
                            option will affect which CPUs will do NFS serving.
                            Note: this parameter cannot be changed while the
                            NFS server is running.

                            auto        the server chooses an appropriate mode
                                        automatically using heuristics
                            global      a single global pool contains all CPUs
                            percpu      one pool for each CPU
                            pernode     one pool for each NUMA node (equivalent
                                        to global on non-NUMA machines)

            sunrpc.tcp_slot_table_entries=
            sunrpc.udp_slot_table_entries=
                            [NFS,SUNRPC]
                            Sets the upper limit on the number of simultaneous
                            RPC calls that can be sent from the client to a
                            server. Increasing these values may allow you to
                            improve throughput, but will also increase the
                            amount of memory reserved for use by the client.

            suspend.pm_test_delay=
                            [SUSPEND]
                            Sets the number of seconds to remain in a suspend test
                            mode before resuming the system (see
                            /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
                            is set. Default value is 5.

            svm=            [PPC]
                            Format: { on | off | y | n | 1 | 0 }
                            This parameter controls use of the Protected
                            Execution Facility on pSeries.

            swapaccount=[0|1]
                            [KNL] Enable accounting of swap in memory resource
                            controller if no parameter or 1 is given or disable
                            it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)

            swiotlb=        [ARM,IA-64,PPC,MIPS,X86]
                            Format: { <int> | force | noforce }
                            <int> -- Number of I/O TLB slabs
                            force -- force using of bounce buffers even if they
                                     wouldn't be automatically used by the kernel
                            noforce -- Never use bounce buffers (for debugging)

            switches=       [HW,M68k]

            sysctl.*=       [KNL]
                            Set a sysctl parameter, right before loading the init
                            process, as if the value was written to the respective
                            /proc/sys/... file. Both '.' and '/' are recognized as
                            separators. Unrecognized parameters and invalid values
                            are reported in the kernel log. Sysctls registered
                            later by a loaded module cannot be set this way.
                            Example: sysctl.vm.swappiness=40

            sysfs.deprecated=0|1 [KNL]
                            Enable/disable old style sysfs layout for old udev
                            on older distributions. When this option is enabled
                            very new udev will not work anymore. When this option
                            is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
                            in older udev will not work anymore.
                            Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
                            the kernel configuration.

            sysrq_always_enabled
                            [KNL]
                            Ignore sysrq setting - this boot parameter will
                            neutralize any effect of /proc/sys/kernel/sysrq.
                            Useful for debugging.

            tcpmhash_entries= [KNL,NET]
                            Set the number of tcp_metrics_hash slots.
                            Default value is 8192 or 16384 depending on total
                            ram pages. This is used to specify the TCP metrics
                            cache size. See Documentation/networking/ip-sysctl.rst
                            "tcp_no_metrics_save" section for more details.

            tdfx=           [HW,DRM]

            test_suspend=   [SUSPEND][,N]
                            Specify "mem" (for Suspend-to-RAM) or "standby" (for
                            standby suspend) or "freeze" (for suspend type freeze)
                            as the system sleep state during system startup with
                            the optional capability to repeat N number of times.
                            The system is woken from this state using a
                            wakeup-capable RTC alarm.

            thash_entries=  [KNL,NET]
                            Set number of hash buckets for TCP connection

            thermal.act=    [HW,ACPI]
                            -1: disable all active trip points in all thermal zones
                            <degrees C>: override all lowest active trip points

            thermal.crt=    [HW,ACPI]
                            -1: disable all critical trip points in all thermal zones
                            <degrees C>: override all critical trip points

            thermal.nocrt=  [HW,ACPI]
                            Set to disable actions on ACPI thermal zone
                            critical and hot trip points.

            thermal.off=    [HW,ACPI]
                            1: disable ACPI thermal control

            thermal.psv=    [HW,ACPI]
                            -1: disable all passive trip points
                            <degrees C>: override all passive trip points to this
                            value

            thermal.tzp=    [HW,ACPI]
                            Specify global default ACPI thermal zone polling rate
                            <deci-seconds>: poll all this frequency
                            0: no polling (default)

            threadirqs      [KNL]
                            Force threading of all interrupt handlers except those
                            marked explicitly IRQF_NO_THREAD.

            topology=       [S390]
                            Format: {off | on}
                            Specify if the kernel should make use of the cpu
                            topology information if the hardware supports this.
                            The scheduler will make use of this information and
                            e.g. base its process migration decisions on it.
                            Default is on.

            topology_updates= [KNL, PPC, NUMA]
                            Format: {off}
                            Specify if the kernel should ignore (off)
                            topology updates sent by the hypervisor to this
                            LPAR.

            torture.disable_onoff_at_boot= [KNL]
                            Prevent the CPU-hotplug component of torturing
                            until after init has spawned.

            torture.ftrace_dump_at_shutdown= [KNL]
                            Dump the ftrace buffer at torture-test shutdown,
                            even if there were no errors.  This can be a
                            very costly operation when many torture tests
                            are running concurrently, especially on systems
                            with rotating-rust storage.

            torture.verbose_sleep_frequency= [KNL]
                            Specifies how many verbose printk()s should be
                            emitted between each sleep.  The default of zero
                            disables verbose-printk() sleeping.

            torture.verbose_sleep_duration= [KNL]
                            Duration of each verbose-printk() sleep in jiffies.

            tp720=          [HW,PS2]

            tpm_suspend_pcr=[HW,TPM]
                            Format: integer pcr id
                            Specify that at suspend time, the tpm driver
                            should extend the specified pcr with zeros,
                            as a workaround for some chips which fail to
                            flush the last written pcr on TPM_SaveState.
                            This will guarantee that all the other pcrs
                            are saved.

            trace_buf_size=nn[KMG]
                            [FTRACE] will set tracing buffer size on each cpu.

            trace_event=[event-list]
                            [FTRACE] Set and start specified trace events in order
                            to facilitate early boot debugging. The event-list is a
                            comma-separated list of trace events to enable. See
                            also Documentation/trace/events.rst

            trace_options=[option-list]
                            [FTRACE] Enable or disable tracer options at boot.
                            The option-list is a comma delimited list of options
                            that can be enabled or disabled just as if you were
                            to echo the option name into

                                /sys/kernel/debug/tracing/trace_options

                            For example, to enable stacktrace option (to dump the
                            stack trace of each event), add to the command line:

                                  trace_options=stacktrace

                            See also Documentation/trace/ftrace.rst "trace options"
                            section.

            tp_printk[FTRACE]
                            Have the tracepoints sent to printk as well as the
                            tracing ring buffer. This is useful for early boot up
                            where the system hangs or reboots and does not give the
                            option for reading the tracing buffer or performing a
                            ftrace_dump_on_oops.

                            To turn off having tracepoints sent to printk,
                             echo 0 > /proc/sys/kernel/tracepoint_printk
                            Note, echoing 1 into this file without the
                            tracepoint_printk kernel cmdline option has no effect.

                            The tp_printk_stop_on_boot (see below) can also be used
                            to stop the printing of events to console at
                            late_initcall_sync.

                            ** CAUTION **

                            Having tracepoints sent to printk() and activating high
                            frequency tracepoints such as irq or sched, can cause
                            the system to live lock.

            tp_printk_stop_on_boot[FTRACE]
                            When tp_printk (above) is set, it can cause a lot of noise
                            on the console. It may be useful to only include the
                            printing of events during boot up, as user space may
                            make the system inoperable.

                            This command line option will stop the printing of events
                            to console at the late_initcall_sync() time frame.

            traceoff_on_warning
                            [FTRACE] enable this option to disable tracing when a
                            warning is hit. This turns off "tracing_on". Tracing can
                            be enabled again by echoing '1' into the "tracing_on"
                            file located in /sys/kernel/debug/tracing/

                            This option is useful, as it disables the trace before
                            the WARNING dump is called, which prevents the trace to
                            be filled with content caused by the warning output.

                            This option can also be set at run time via the sysctl
                            option:  kernel/traceoff_on_warning

            transparent_hugepage=
                            [KNL]
                            Format: [always|madvise|never]
                            Can be used to control the default behavior of the system
                            with respect to transparent hugepages.
                            See Documentation/admin-guide/mm/transhuge.rst
                            for more details.

            trusted.source= [KEYS]
                            Format: <string>
                            This parameter identifies the trust source as a backend
                            for trusted keys implementation. Supported trust
                            sources:
                            - "tpm"
                            - "tee"
                            If not specified then it defaults to iterating through
                            the trust source list starting with TPM and assigns the
                            first trust source as a backend which is initialized
                            successfully during iteration.

            tsc=            Disable clocksource stability checks for TSC.
                            Format: <string>
                            [x86] reliable: mark tsc clocksource as reliable, this
                            disables clocksource verification at runtime, as well
                            as the stability checks done at bootup. Used to enable
                            high-resolution timer mode on older hardware, and in
                            virtualized environment.
                            [x86] noirqtime: Do not use TSC to do irq accounting.
                            Used to run time disable IRQ_TIME_ACCOUNTING on any
                            platforms where RDTSC is slow and this accounting
                            can add overhead.
                            [x86] unstable: mark the TSC clocksource as unstable, this
                            marks the TSC unconditionally unstable at bootup and
                            avoids any further wobbles once the TSC watchdog notices.
                            [x86] nowatchdog: disable clocksource watchdog. Used
                            in situations with strict latency requirements (where
                            interruptions from clocksource watchdog are not
                            acceptable).

            tsc_early_khz=  [X86] Skip early TSC calibration and use the given
                            value instead. Useful when the early TSC frequency discovery
                            procedure is not reliable, such as on overclocked systems
                            with CPUID.16h support and partial CPUID.15h support.
                            Format: <unsigned int>

            tsx=            [X86] Control Transactional Synchronization
                            Extensions (TSX) feature in Intel processors that
                            support TSX control.

                            This parameter controls the TSX feature. The options are:

                            on      - Enable TSX on the system. Although there are
                                    mitigations for all known security vulnerabilities,
                                    TSX has been known to be an accelerator for
                                    several previous speculation-related CVEs, and
                                    so there may be unknown security risks associated
                                    with leaving it enabled.

                            off     - Disable TSX on the system. (Note that this
                                    option takes effect only on newer CPUs which are
                                    not vulnerable to MDS, i.e., have
                                    MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
                                    the new IA32_TSX_CTRL MSR through a microcode
                                    update. This new MSR allows for the reliable
                                    deactivation of the TSX functionality.)

                            auto    - Disable TSX if X86_BUG_TAA is present,
                                      otherwise enable TSX on the system.

                            Not specifying this option is equivalent to tsx=off.

                            See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
                            for more details.

            tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
                            Abort (TAA) vulnerability.

                            Similar to Micro-architectural Data Sampling (MDS)
                            certain CPUs that support Transactional
                            Synchronization Extensions (TSX) are vulnerable to an
                            exploit against CPU internal buffers which can forward
                            information to a disclosure gadget under certain
                            conditions.

                            In vulnerable processors, the speculatively forwarded
                            data can be used in a cache side channel attack, to
                            access data to which the attacker does not have direct
                            access.

                            This parameter controls the TAA mitigation.  The
                            options are:

                            full       - Enable TAA mitigation on vulnerable CPUs
                                         if TSX is enabled.

                            full,nosmt - Enable TAA mitigation and disable SMT on
                                         vulnerable CPUs. If TSX is disabled, SMT
                                         is not disabled because CPU is not
                                         vulnerable to cross-thread TAA attacks.
                            off        - Unconditionally disable TAA mitigation

                            On MDS-affected machines, tsx_async_abort=off can be
                            prevented by an active MDS mitigation as both vulnerabilities
                            are mitigated with the same mechanism so in order to disable
                            this mitigation, you need to specify mds=off too.

                            Not specifying this option is equivalent to
                            tsx_async_abort=full.  On CPUs which are MDS affected
                            and deploy MDS mitigation, TAA mitigation is not
                            required and doesn't provide any additional
                            mitigation.

                            For details see:
                            Documentation/admin-guide/hw-vuln/tsx_async_abort.rst

            turbografx.map[2|3]=    [HW,JOY]
                            TurboGraFX parallel port interface
                            Format:
                            <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
                            See also Documentation/input/devices/joystick-parport.rst

            udbg-immortal   [PPC] When debugging early kernel crashes that
                            happen after console_init() and before a proper
                            console driver takes over, this boot options might
                            help "seeing" what's going on.

            uhash_entries=  [KNL,NET]
                            Set number of hash buckets for UDP/UDP-Lite connections

            uhci-hcd.ignore_oc=
                            [USB] Ignore overcurrent events (default N).
                            Some badly-designed motherboards generate lots of
                            bogus events, for ports that aren't wired to
                            anything.  Set this parameter to avoid log spamming.
                            Note that genuine overcurrent events won't be
                            reported either.

            unknown_nmi_panic
                            [X86] Cause panic on unknown NMI.

            usbcore.authorized_default=
                            [USB] Default USB device authorization:
                            (default -1 = authorized except for wireless USB,
                            0 = not authorized, 1 = authorized, 2 = authorized
                            if device connected to internal port)

            usbcore.autosuspend=
                            [USB] The autosuspend time delay (in seconds) used
                            for newly-detected USB devices (default 2).  This
                            is the time required before an idle device will be
                            autosuspended.  Devices for which the delay is set
                            to a negative value won't be autosuspended at all.

            usbcore.usbfs_snoop=
                            [USB] Set to log all usbfs traffic (default 0 = off).

            usbcore.usbfs_snoop_max=
                            [USB] Maximum number of bytes to snoop in each URB
                            (default = 65536).

            usbcore.blinkenlights=
                            [USB] Set to cycle leds on hubs (default 0 = off).

            usbcore.old_scheme_first=
                            [USB] Start with the old device initialization
                            scheme (default 0 = off).

            usbcore.usbfs_memory_mb=
                            [USB] Memory limit (in MB) for buffers allocated by
                            usbfs (default = 16, 0 = max = 2047).

            usbcore.use_both_schemes=
                            [USB] Try the other device initialization scheme
                            if the first one fails (default 1 = enabled).

            usbcore.initial_descriptor_timeout=
                            [USB] Specifies timeout for the initial 64-byte
                            USB_REQ_GET_DESCRIPTOR request in milliseconds
                            (default 5000 = 5.0 seconds).

            usbcore.nousb   [USB] Disable the USB subsystem

            usbcore.quirks=
                            [USB] A list of quirk entries to augment the built-in
                            usb core quirk list. List entries are separated by
                            commas. Each entry has the form
                            VendorID:ProductID:Flags. The IDs are 4-digit hex
                            numbers and Flags is a set of letters. Each letter
                            will change the built-in quirk; setting it if it is
                            clear and clearing it if it is set. The letters have
                            the following meanings:
                                    a = USB_QUIRK_STRING_FETCH_255 (string
                                            descriptors must not be fetched using
                                            a 255-byte read);
                                    b = USB_QUIRK_RESET_RESUME (device can't resume
                                            correctly so reset it instead);
                                    c = USB_QUIRK_NO_SET_INTF (device can't handle
                                            Set-Interface requests);
                                    d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
                                            handle its Configuration or Interface
                                            strings);
                                    e = USB_QUIRK_RESET (device can't be reset
                                            (e.g morph devices), don't use reset);
                                    f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
                                            more interface descriptions than the
                                            bNumInterfaces count, and can't handle
                                            talking to these interfaces);
                                    g = USB_QUIRK_DELAY_INIT (device needs a pause
                                            during initialization, after we read
                                            the device descriptor);
                                    h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
                                            high speed and super speed interrupt
                                            endpoints, the USB 2.0 and USB 3.0 spec
                                            require the interval in microframes (1
                                            microframe = 125 microseconds) to be
                                            calculated as interval = 2 ^
                                            (bInterval-1).
                                            Devices with this quirk report their
                                            bInterval as the result of this
                                            calculation instead of the exponent
                                            variable used in the calculation);
                                    i = USB_QUIRK_DEVICE_QUALIFIER (device can't
                                            handle device_qualifier descriptor
                                            requests);
                                    j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
                                            generates spurious wakeup, ignore
                                            remote wakeup capability);
                                    k = USB_QUIRK_NO_LPM (device can't handle Link
                                            Power Management);
                                    l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
                                            (Device reports its bInterval as linear
                                            frames instead of the USB 2.0
                                            calculation);
                                    m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
                                            to be disconnected before suspend to
                                            prevent spurious wakeup);
                                    n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
                                            pause after every control message);
                                    o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
                                            delay after resetting its port);
                            Example: quirks=0781:5580:bk,0a5c:5834:gij

            usbhid.mousepoll=
                            [USBHID] The interval which mice are to be polled at.

            usbhid.jspoll=
                            [USBHID] The interval which joysticks are to be polled at.

            usbhid.kbpoll=
                            [USBHID] The interval which keyboards are to be polled at.

            usb-storage.delay_use=
                            [UMS] The delay in seconds before a new device is
                            scanned for Logical Units (default 1).

            usb-storage.quirks=
                            [UMS] A list of quirks entries to supplement or
                            override the built-in unusual_devs list.  List
                            entries are separated by commas.  Each entry has
                            the form VID:PID:Flags where VID and PID are Vendor
                            and Product ID values (4-digit hex numbers) and
                            Flags is a set of characters, each corresponding
                            to a common usb-storage quirk flag as follows:
                                    a = SANE_SENSE (collect more than 18 bytes
                                            of sense data, not on uas);
                                    b = BAD_SENSE (don't collect more than 18
                                            bytes of sense data, not on uas);
                                    c = FIX_CAPACITY (decrease the reported
                                            device capacity by one sector);
                                    d = NO_READ_DISC_INFO (don't use
                                            READ_DISC_INFO command, not on uas);
                                    e = NO_READ_CAPACITY_16 (don't use
                                            READ_CAPACITY_16 command);
                                    f = NO_REPORT_OPCODES (don't use report opcodes
                                            command, uas only);
                                    g = MAX_SECTORS_240 (don't transfer more than
                                            240 sectors at a time, uas only);
                                    h = CAPACITY_HEURISTICS (decrease the
                                            reported device capacity by one
                                            sector if the number is odd);
                                    i = IGNORE_DEVICE (don't bind to this
                                            device);
                                    j = NO_REPORT_LUNS (don't use report luns
                                            command, uas only);
                                    k = NO_SAME (do not use WRITE_SAME, uas only)
                                    l = NOT_LOCKABLE (don't try to lock and
                                            unlock ejectable media, not on uas);
                                    m = MAX_SECTORS_64 (don't transfer more
                                            than 64 sectors = 32 KB at a time,
                                            not on uas);
                                    n = INITIAL_READ10 (force a retry of the
                                            initial READ(10) command, not on uas);
                                    o = CAPACITY_OK (accept the capacity
                                            reported by the device, not on uas);
                                    p = WRITE_CACHE (the device cache is ON
                                            by default, not on uas);
                                    r = IGNORE_RESIDUE (the device reports
                                            bogus residue values, not on uas);
                                    s = SINGLE_LUN (the device has only one
                                            Logical Unit);
                                    t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
                                            commands, uas only);
                                    u = IGNORE_UAS (don't bind to the uas driver);
                                    w = NO_WP_DETECT (don't test whether the
                                            medium is write-protected).
                                    y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
                                            even if the device claims no cache,
                                            not on uas)
                            Example: quirks=0419:aaf5:rl,0421:0433:rc

            user_debug=     [KNL,ARM]
                            Format: <int>
                            See arch/arm/Kconfig.debug help text.
                                     1 - undefined instruction events
                                     2 - system calls
                                     4 - invalid data aborts
                                     8 - SIGSEGV faults
                                    16 - SIGBUS faults
                            Example: user_debug=31

            userpte=
                            [X86] Flags controlling user PTE allocations.

                                    nohigh = do not allocate PTE pages in
                                            HIGHMEM regardless of setting
                                            of CONFIG_HIGHPTE.

            vdso=           [X86,SH]
                            On X86_32, this is an alias for vdso32=.  Otherwise:

                            vdso=1: enable VDSO (the default)
                            vdso=0: disable VDSO mapping

            vdso32=         [X86] Control the 32-bit vDSO
                            vdso32=1: enable 32-bit VDSO
                            vdso32=0 or vdso32=2: disable 32-bit VDSO

                            See the help text for CONFIG_COMPAT_VDSO for more
                            details.  If CONFIG_COMPAT_VDSO is set, the default is
                            vdso32=0; otherwise, the default is vdso32=1.

                            For compatibility with older kernels, vdso32=2 is an
                            alias for vdso32=0.

                            Try vdso32=0 if you encounter an error that says:
                            dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!

            vector=         [IA-64,SMP]
                            vector=percpu: enable percpu vector domain

            video=          [FB] Frame buffer configuration
                            See Documentation/fb/modedb.rst.

            video.brightness_switch_enabled= [0,1]
                            If set to 1, on receiving an ACPI notify event
                            generated by hotkey, video driver will adjust brightness
                            level and then send out the event to user space through
                            the allocated input device; If set to 0, video driver
                            will only send out the event without touching backlight
                            brightness level.
                            default: 1

            virtio_mmio.device=
                            [VMMIO] Memory mapped virtio (platform) device.

                                    <size>@<baseaddr>:<irq>[:<id>]
                            where:
                                    <size>     := size (can use standard suffixes
                                                    like K, M and G)
                                    <baseaddr> := physical base address
                                    <irq>      := interrupt number (as passed to
                                                    request_irq())
                                    <id>       := (optional) platform device id
                            example:
                                    virtio_mmio.device=1K@0x100b0000:48:7

                            Can be used multiple times for multiple devices.

            vga=            [BOOT,X86-32] Select a particular video mode
                            See Documentation/x86/boot.rst and
                            Documentation/admin-guide/svga.rst.
                            Use vga=ask for menu.
                            This is actually a boot loader parameter; the value is
                            passed to the kernel using a special protocol.

            vm_debug[=options]      [KNL] Available with CONFIG_DEBUG_VM=y.
                            May slow down system boot speed, especially when
                            enabled on systems with a large amount of memory.
                            All options are enabled by default, and this
                            interface is meant to allow for selectively
                            enabling or disabling specific virtual memory
                            debugging features.

                            Available options are:
                              P     Enable page structure init time poisoning
                              -     Disable all of the above options

            vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
                            size of <nn>. This can be used to increase the
                            minimum size (128MB on x86). It can also be used to
                            decrease the size and leave more room for directly
                            mapped kernel RAM.

            vmcp_cma=nn[MG] [KNL,S390]
                            Sets the memory size reserved for contiguous memory
                            allocations for the vmcp device driver.

            vmhalt=         [KNL,S390] Perform z/VM CP command after system halt.
                            Format: <command>

            vmpanic=        [KNL,S390] Perform z/VM CP command after kernel panic.
                            Format: <command>

            vmpoff=         [KNL,S390] Perform z/VM CP command after power off.
                            Format: <command>

            vsyscall=       [X86-64]
                            Controls the behavior of vsyscalls (i.e. calls to
                            fixed addresses of 0xffffffffff600x00 from legacy
                            code).  Most statically-linked binaries and older
                            versions of glibc use these calls.  Because these
                            functions are at fixed addresses, they make nice
                            targets for exploits that can control RIP.

                            emulate     [default] Vsyscalls turn into traps and are
                                        emulated reasonably safely.  The vsyscall
                                        page is readable.

                            xonly       Vsyscalls turn into traps and are
                                        emulated reasonably safely.  The vsyscall
                                        page is not readable.

                            none        Vsyscalls don't work at all.  This makes
                                        them quite hard to use for exploits but
                                        might break your system.

            vt.color=       [VT] Default text color.
                            Format: 0xYX, X = foreground, Y = background.
                            Default: 0x07 = light gray on black.

            vt.cur_default= [VT] Default cursor shape.
                            Format: 0xCCBBAA, where AA, BB, and CC are the same as
                            the parameters of the <Esc>[?A;B;Cc escape sequence;
                            see VGA-softcursor.txt. Default: 2 = underline.

            vt.default_blu= [VT]
                            Format: <blue0>,<blue1>,<blue2>,...,<blue15>
                            Change the default blue palette of the console.
                            This is a 16-member array composed of values
                            ranging from 0-255.

            vt.default_grn= [VT]
                            Format: <green0>,<green1>,<green2>,...,<green15>
                            Change the default green palette of the console.
                            This is a 16-member array composed of values
                            ranging from 0-255.

            vt.default_red= [VT]
                            Format: <red0>,<red1>,<red2>,...,<red15>
                            Change the default red palette of the console.
                            This is a 16-member array composed of values
                            ranging from 0-255.

            vt.default_utf8=
                            [VT]
                            Format=<0|1>
                            Set system-wide default UTF-8 mode for all tty's.
                            Default is 1, i.e. UTF-8 mode is enabled for all
                            newly opened terminals.

            vt.global_cursor_default=
                            [VT]
                            Format=<-1|0|1>
                            Set system-wide default for whether a cursor
                            is shown on new VTs. Default is -1,
                            i.e. cursors will be created by default unless
                            overridden by individual drivers. 0 will hide
                            cursors, 1 will display them.

            vt.italic=      [VT] Default color for italic text; 0-15.
                            Default: 2 = green.

            vt.underline=   [VT] Default color for underlined text; 0-15.
                            Default: 3 = cyan.

            watchdog timers [HW,WDT] For information on watchdog timers,
                            see Documentation/watchdog/watchdog-parameters.rst
                            or other driver-specific files in the
                            Documentation/watchdog/ directory.

            watchdog_thresh=
                            [KNL]
                            Set the hard lockup detector stall duration
                            threshold in seconds. The soft lockup detector
                            threshold is set to twice the value. A value of 0
                            disables both lockup detectors. Default is 10
                            seconds.

            workqueue.watchdog_thresh=
                            If CONFIG_WQ_WATCHDOG is configured, workqueue can
                            warn stall conditions and dump internal state to
                            help debugging.  0 disables workqueue stall
                            detection; otherwise, it's the stall threshold
                            duration in seconds.  The default value is 30 and
                            it can be updated at runtime by writing to the
                            corresponding sysfs file.

            workqueue.disable_numa
                            By default, all work items queued to unbound
                            workqueues are affine to the NUMA nodes they're
                            issued on, which results in better behavior in
                            general.  If NUMA affinity needs to be disabled for
                            whatever reason, this option can be used.  Note
                            that this also can be controlled per-workqueue for
                            workqueues visible under /sys/bus/workqueue/.

            workqueue.power_efficient
                            Per-cpu workqueues are generally preferred because
                            they show better performance thanks to cache
                            locality; unfortunately, per-cpu workqueues tend to
                            be more power hungry than unbound workqueues.

                            Enabling this makes the per-cpu workqueues which
                            were observed to contribute significantly to power
                            consumption unbound, leading to measurably lower
                            power usage at the cost of small performance
                            overhead.

                            The default value of this parameter is determined by
                            the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.

            workqueue.debug_force_rr_cpu
                            Workqueue used to implicitly guarantee that work
                            items queued without explicit CPU specified are put
                            on the local CPU.  This guarantee is no longer true
                            and while local CPU is still preferred work items
                            may be put on foreign CPUs.  This debug option
                            forces round-robin CPU selection to flush out
                            usages which depend on the now broken guarantee.
                            When enabled, memory and cache locality will be
                            impacted.

            x2apic_phys     [X86-64,APIC] Use x2apic physical mode instead of
                            default x2apic cluster mode on platforms
                            supporting x2apic.

            xen_512gb_limit         [KNL,X86-64,XEN]
                            Restricts the kernel running paravirtualized under Xen
                            to use only up to 512 GB of RAM. The reason to do so is
                            crash analysis tools and Xen tools for doing domain
                            save/restore/migration must be enabled to handle larger
                            domains.

            xen_emul_unplug=                [HW,X86,XEN]
                            Unplug Xen emulated devices
                            Format: [unplug0,][unplug1]
                            ide-disks -- unplug primary master IDE devices
                            aux-ide-disks -- unplug non-primary-master IDE devices
                            nics -- unplug network devices
                            all -- unplug all emulated devices (NICs and IDE disks)
                            unnecessary -- unplugging emulated devices is
                                    unnecessary even if the host did not respond to
                                    the unplug protocol
                            never -- do not unplug even if version check succeeds

            xen_legacy_crash        [X86,XEN]
                            Crash from Xen panic notifier, without executing late
                            panic() code such as dumping handler.

            xen_nopvspin    [X86,XEN]
                            Disables the qspinlock slowpath using Xen PV optimizations.
                            This parameter is obsoleted by "nopvspin" parameter, which
                            has equivalent effect for XEN platform.

            xen_nopv        [X86]
                            Disables the PV optimizations forcing the HVM guest to
                            run as generic HVM guest with no PV drivers.
                            This option is obsoleted by the "nopv" option, which
                            has equivalent effect for XEN platform.

            xen_no_vector_callback
                            [KNL,X86,XEN] Disable the vector callback for Xen
                            event channel interrupts.

            xen_scrub_pages=        [XEN]
                            Boolean option to control scrubbing pages before giving them back
                            to Xen, for use by other domains. Can be also changed at runtime
                            with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
                            Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.

            xen_timer_slop= [X86-64,XEN]
                            Set the timer slop (in nanoseconds) for the virtual Xen
                            timers (default is 100000). This adjusts the minimum
                            delta of virtualized Xen timers, where lower values
                            improve timer resolution at the expense of processing
                            more timer interrupts.

            xen.balloon_boot_timeout= [XEN]
                            The time (in seconds) to wait before giving up to boot
                            in case initial ballooning fails to free enough memory.
                            Applies only when running as HVM or PVH guest and
                            started with less memory configured than allowed at
                            max. Default is 180.

            xen.event_eoi_delay=    [XEN]
                            How long to delay EOI handling in case of event
                            storms (jiffies). Default is 10.

            xen.event_loop_timeout= [XEN]
                            After which time (jiffies) the event handling loop
                            should start to delay EOI handling. Default is 2.

            xen.fifo_events=        [XEN]
                            Boolean parameter to disable using fifo event handling
                            even if available. Normally fifo event handling is
                            preferred over the 2-level event handling, as it is
                            fairer and the number of possible event channels is
                            much higher. Default is on (use fifo events).

            nopv=           [X86,XEN,KVM,HYPER_V,VMWARE]
                            Disables the PV optimizations forcing the guest to run
                            as generic guest with no PV drivers. Currently support
                            XEN HVM, KVM, HYPER_V and VMWARE guest.

            nopvspin        [X86,XEN,KVM]
                            Disables the qspinlock slow path using PV optimizations
                            which allow the hypervisor to 'idle' the guest on lock
                            contention.

            xirc2ps_cs=     [NET,PCMCIA]
                            Format:
                            <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]

            xive=           [PPC]
                            By default on POWER9 and above, the kernel will
                            natively use the XIVE interrupt controller. This option
                            allows the fallback firmware mode to be used:

                            off       Fallback to firmware control of XIVE interrupt
                                      controller on both pseries and powernv
                                      platforms. Only useful on POWER9 and above.

            xive.store-eoi=off      [PPC]
                            By default on POWER10 and above, the kernel will use
                            stores for EOI handling when the XIVE interrupt mode
                            is active. This option allows the XIVE driver to use
                            loads instead, as on POWER9.

            xhci-hcd.quirks         [USB,KNL]
                            A hex value specifying bitmask with supplemental xhci
                            host controller quirks. Meaning of each bit can be
                            consulted in header drivers/usb/host/xhci.h.

            xmon            [PPC]
                            Format: { early | on | rw | ro | off }
                            Controls if xmon debugger is enabled. Default is off.
                            Passing only "xmon" is equivalent to "xmon=early".
                            early   Call xmon as early as possible on boot; xmon
                                    debugger is called from setup_arch().
                            on      xmon debugger hooks will be installed so xmon
                                    is only called on a kernel crash. Default mode,
                                    i.e. either "ro" or "rw" mode, is controlled
                                    with CONFIG_XMON_DEFAULT_RO_MODE.
                            rw      xmon debugger hooks will be installed so xmon
                                    is called only on a kernel crash, mode is write,
                                    meaning SPR registers, memory and, other data
                                    can be written using xmon commands.
                            ro      same as "rw" option above but SPR registers,
                                    memory, and other data can't be written using
                                    xmon commands.
                            off     xmon is disabled.

## Todo

> Add more DRM drivers.