linuxカーネルが許容できるパラメータ|Linux kernel起動パラメータ|grubを介してカーネルにパラメータを渡す

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Linuxでは、kernelにパラメータを渡して動作を制御するには、3つの方法があります.
1.build kernelの場合の各configurationオプション.
2.kernelが起動されると、GRUBやLILOなどの起動プログラムによってkernelが呼び出されたときにkernelにパラメータを渡すことができる.
3.kernelの実行時に、/procまたは/sysディレクトリの下のファイルを変更します.
ここで簡単に言えば、kernelがgrubで構成した起動パラメータの2つ目の方法です.
まずkernelにはどのようなパラメータがありますか?linuxのソースコードには、このようなドキュメントDocumentation/kernel-parametersがあります.txtはkernelの各パラメータとその意味を紹介した.
次に、kernel起動パラメータはスペースで区切られ、大文字と小文字を厳密に区別します(memとMEMは異なります).
再度、module特有のkernelパラメータの書き方は、[module name]である.[parameter=XX]例えばigb.max_vfs=7というkernel起動パラメータの効果は、module:modprobe igb max_を動的にロードすることに相当する.vfs=7
またkernelはこれらの起動パラメータをどのように処理していますか?起動パラメータは、通常、name[=value_1][value_2]...[,value_10]の形式です.
「name」はキーワードであり、カーネルは「キーワード」の後ろの値を誰に渡すべきか、つまりこの値をどのように処理するか、処理プロセスに渡すか、それとも環境変数として投げるか、あるいは「init」に投げるべきかを識別する.値の個数は10に制限され、このキーワードを再び使用して10を超えるパラメータを使用することができます.まず、kernelはキーワードが「root=」,「nfsroot=」,「nfsaddrs=」,「ro」,「rw」,「debug」または「init」であるかどうかをチェックし、カーネルはbootsetups配列でキーワードに関連付けられた登録された処理関数を検索し、関連する登録された処理関数が見つかった場合、これらの関数を呼び出し、キーワードの後の値をパラメータとしてこれらの関数に渡す.たとえば、起動時にパラメータname=a,b,c,d,カーネルを設定してbootsetups配列を検索し、「name」が登録されていることが判明した場合、「name」の設定関数を呼び出します.例えばname_setup()は、a,b,c,dをname_に渡します.setup()を実行します.すべての「name=value」パラメータは、上述した設定関数によって受信されなければ、システム起動後の環境変数、例えば「TERM=vt 100」起動パラメータが起動後の環境変数として解釈される.カーネル設定関数によって受信されず、環境変数に設定されていないすべてのパラメータは、「single」などのinitプロセス処理に残されます.
私が仕事でよく使うkernel起動パラメータを簡単にまとめましょう.
ルートディスク関連起動パラメータ:
root#は、root=/dev/sda 1などのルートファイルシステムを起動することを示します.
ロ#ルートデバイスが起動中にread-onlyであることを指定します.デフォルトでは一般的にこのように配置されています.
rw#はroと似ています.read-writeと規定されています.書くことができます.
rootfstype#ルートファイルシステムタイプ(rootfstype=ext 4など)
Consoleおよびkernel log関連起動パラメータ:
console#consoleのデバイスとオプション、例えばconsole=tty 0 console=ttyS 0
debug#enable kernel debugging起動中のすべてのdebug情報がconsoleに印刷されます
quiet#disable all log messages kernel log levelをKERN_に設定WARNINGは、起動中に非常に深刻な情報しかありません
loglevel#デフォルトのconsoleログレベルを設定します.たとえば、loglevel=7(0~7の数字はそれぞれ:KERN_EMERG,.,KERN_DEBUG)
time#設定kernel log情報ごとにタイムスタンプを付ける
メモリ関連起動パラメータ:
mem#kernelが使用するメモリ量を指定し、mem=n[KMG]
hugepages#大きなページのページ(4 MBサイズ)の最大数を設定します.hugepages=n
CPU関連起動パラメータ:
mce # Enable the machine check exception feature.
nosmp #Run as a single-processor machine. SMPを使用しない(マルチプロセッサ)
max_cpus #max_cpus=n,SMPシステムで最大使用可能なCPU数(システム中にn個より大きいCPUがあっても)
Ramdisk関連起動パラメータ:
initrd#ramdiskを初期化する場所を指定し、initrd=filename
noinitrd#initrdパラメータが構成されていてもinitrdの構成は使用されません.
関連する起動パラメータを初期化します.
init#起動時に実行するプログラム、init=filename、デフォルト値は/sbin/init
PCI関連起動パラメータ:
pci#pci関連のオプションは、pci=assign_をよく使います.buses、pci=nomsiも使用したことがあります
SELinux関連起動パラメータ:
Enforcing#SELinux enforcing状態のスイッチで、enforcing=0はアクセスを阻止するのではなく危険を記録するだけで、enforcing=1は完全にenableで、デフォルト値は0です
selinux#は起動時にSELinuxを閉じるか開く、selinux=0は閉じる、selinux=1はselinuxを開く
また、max_を使いますloopは、最も使用可能なループデバイスを指定します.
Redhatのシステムでは、よく見られるkernel起動パラメータであるrhgbがあり、rhgbはredhat graphics bootを表し、起動中に表示されるテキスト情報の代わりに画像を見ることができます.これらの情報は、起動後にdmesgでもrhgb=redhat graphical boot-This a GUI mode booting screen with most of the information hidden while the user sees a rotating activity icon spining and brief information as to what the computer is doingを見ることができる.
quiet = hides the majority of boot messages before rhgb starts. These are supposed to make the common user more comfortable. They get alarmed about seeing the kernel and initializing messages, so they hide them for their comfort.
参考資料:
linux kernel documents
《Linux kernel in a nutshell》
 
                          Kernel Parameters

                          ~~~~~~~~~~~~~~~~~



The following is a consolidated list of the kernel parameters as implemented

(mostly) by the __setup() macro 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.



Module parameters for loadable modules are specified only as the

parameter name with optional '=' and value as appropriate, such as:



    modprobe usbcore blinkenlights=1



Module parameters for modules that are built into the kernel image

are specified on the kernel command line with the module name plus

'.' plus parameter name, with '=' and value if appropriate, such as:



    usbcore.blinkenlights=1



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





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.

    AVR32    AVR32 architecture is enabled.

    AX25    Appropriate AX.25 support is enabled.

    BLACKFIN Blackfin architecture is enabled.

    DRM    Direct Rendering Management support is enabled.

    EDD    BIOS Enhanced Disk Drive Services (EDD) is enabled

    EFI    EFI Partitioning (GPT) is enabled

    EIDE    EIDE/ATAPI support is enabled.

    FB    The frame buffer device is 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.

    ISAPNP    ISA PnP code is enabled.

    ISDN    Appropriate ISDN support is enabled.

    JOY    Appropriate joystick 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.txt.

    MCA    MCA bus support is enabled.

    MDA    MDA console support 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.

    GENERIC_TIME The generic timeofday code is enabled.

    NFS    Appropriate NFS support 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.

    ROOTPLUG The example Root Plug LSM is enabled.

    S390    S390 architecture is enabled.

    SCSI    Appropriate SCSI support is enabled.

            A lot of drivers has their options described inside of

            Documentation/scsi/.

    SECURITY Different security models are enabled.

    SELINUX SELinux 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.

    FTRACE    Function tracing 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.

    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.txt .

    X86    Either 32bit or 64bit x86 (same as X86-32+X86-64)



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 <Documentation/x86/boot.txt>.



There are also arch-specific kernel-parameters not documented here.

See for example <Documentation/x86/x86_64/boot-options.txt>.



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.





    acpi=        [HW,ACPI,X86]

            Advanced Configuration and Power Interface

            Format: { force | off | ht | strict | noirq | rsdt }

            force -- enable ACPI if default was off

            off -- disable ACPI if default was on

            noirq -- do not use ACPI for IRQ routing

            ht -- run only enough ACPI to enable Hyper Threading

            strict -- Be less tolerant of platforms that are not

                strictly ACPI specification compliant.

            rsdt -- prefer RSDT over (default) XSDT



            See also Documentation/power/pm.txt, 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]

            acpi_backlight=vendor

            acpi_backlight=video

            If set to vendor, prefer vendor specific driver

            (e.g. thinkpad_acpi, sony_acpi, etc.) instead

            of the ACPI video.ko driver.



    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_PCI_COMPONENT

            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/acpi/debug.txt for more information about

            debug layers and levels.



            Enable processor driver info messages:

                acpi.debug_layer=0x20000000

            Enable PCI/PCI interrupt routing info messages:

                acpi.debug_layer=0x400000

            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_display_output=    [HW,ACPI]

            acpi_display_output=vendor

            acpi_display_output=video

            See above.



    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_no_auto_ssdt    [HW,ACPI] Disable automatic loading of SSDT



    acpi_os_name=    [HW,ACPI] Tell ACPI BIOS the name of the OS

            Format: To spoof as Windows 98: ="Microsoft Windows"



    acpi_osi=    [HW,ACPI] Modify list of supported OS interface strings

            acpi_osi="string1"    # add string1 -- only one string

            acpi_osi="!string2"    # remove built-in string2

            acpi_osi=        # disable all strings



    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_serialize    [HW,ACPI] force serialization of AML methods



    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_nohwsig,

                  old_ordering, s4_nonvs }

            See Documentation/power/video.txt 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_nohwsig prevents ACPI hardware signature from being

            used during resume from hibernation.

            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).

            s4_nonvs prevents the kernel from saving/restoring the

            ACPI NVS memory during hibernation.



    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



    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.



    ad1848=        [HW,OSS]

            Format: <io>,<irq>,<dma>,<dma2>,<type>



    add_efi_memmap    [EFI; X86] Include EFI memory map in

            kernel's map of available physical RAM.



    advansys=    [HW,SCSI]

            See header of drivers/scsi/advansys.c.



    advwdt=        [HW,WDT] Advantech WDT

            Format: <iostart>,<iostop>



    aedsp16=    [HW,OSS] Audio Excel DSP 16

            Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>

            See also header of sound/oss/aedsp16.c.



    agp=        [AGP]

            { off | try_unsupported }

            off: disable AGP support

            try_unsupported: try to drive unsupported chipsets

                (may crash computer or cause data corruption)



    aha152x=    [HW,SCSI]

            See Documentation/scsi/aha152x.txt.



    aha1542=    [HW,SCSI]

            Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]



    aic7xxx=    [HW,SCSI]

            See Documentation/scsi/aic7xxx.txt.



    aic79xx=    [HW,SCSI]

            See Documentation/scsi/aic79xx.txt.



    amd_iommu=    [HW,X86-84]

            Pass parameters to the AMD IOMMU driver in the system.

            Possible values are:

            isolate - enable device isolation (each device, as far

                      as possible, will get its own protection

                      domain) [default]

            share - put every device behind one IOMMU into the

                same protection domain

            fullflush - enable flushing of IO/TLB entries when

                    they are unmapped. Otherwise they are

                    flushed before they will be reused, which

                    is a lot of faster



    amijoy.map=    [HW,JOY] Amiga joystick support

            Map of devices attached to JOY0DAT and JOY1DAT

            Format: <a>,<b>

            See also Documentation/kernel/input/joystick.txt



    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,X86-32] Advanced Programmable Interrupt Controller

            Change the output verbosity whilst booting

            Format: { quiet (default) | verbose | debug }

            Change the amount of debugging information output

            when initialising the APIC and IO-APIC components.



    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>



    ataflop=    [HW,M68k]



    atarimouse=    [HW,MOUSE] Atari Mouse



    atascsi=    [HW,SCSI] Atari SCSI



    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



    autotest    [IA64]



    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.



    boot_delay=    Milliseconds to delay each printk during boot.

            Values larger than 10 seconds (10000) are changed to

            no delay (0).

            Format: integer



    bootmem_debug    [KNL] Enable bootmem allocator debug messages.



    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/video4linux/bttv/Insmod-options

    bttv.tuner=    and Documentation/video4linux/bttv/CARDLIST



    BusLogic=    [HW,SCSI]

            See drivers/scsi/BusLogic.c, comment before function

            BusLogic_ParseDriverOptions().



    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.



    capability.disable=

            [SECURITY] Disable capabilities.  This would normally

            be used only if an alternative security model is to be

            configured.  Potentially dangerous and should only be

            used if you are entirely sure of the consequences.



    ccw_timeout_log [S390]

            See Documentation/s390/CommonIO for details.



    cgroup_disable= [KNL] Disable a particular controller

            Format: {name of the controller(s) to disable}

                {Currently supported controllers - "memory"}



    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

                /selinux/checkreqprot.



    cio_ignore=    [S390]

            See Documentation/s390/CommonIO for details.



    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=    [GENERIC_TIME] 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

            [AVR32] avr32

            [X86-32] pit,hpet,tsc,vmi-timer;

                scx200_hrt on Geode; cyclone on IBM x440

            [MIPS] MIPS

            [PARISC] cr16

            [S390] tod

            [SH] SuperH

            [SPARC64] tick

            [X86-64] hpet,tsc



    clearcpuid=BITNUM [X86]

            Disable CPUID feature X for the kernel. See

            arch/x86/include/asm/cpufeature.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.



    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



    code_bytes    [X86] How many bytes of object code to print

            in an oops report.

            Range: 0 - 8192

            Default: 64



    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/serial-console.txt for more

            information.  See

            Documentation/networking/netconsole.txt for an

            alternative.



        uart[8250],io,<addr>[,options]

        uart[8250],mmio,<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.  The

            options are the same as for ttyS, above.



                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.



    consoleblank=    [KNL] The console blank (screen saver) timeout in

            seconds. Defaults to 10*60 = 10mins. A value of 0

            disables the blank timer.



    coredump_filter=

            [KNL] Change the default value for

            /proc/<pid>/coredump_filter.

            See also Documentation/filesystems/proc.txt.



    cpcihp_generic=    [HW,PCI] Generic port I/O CompactPCI driver

            Format:

            <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]



    crashkernel=nn[KMG]@ss[KMG]

            [KNL] Reserve a chunk of physical memory to

            hold a kernel to switch to with kexec on panic.



    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/kdump/kdump.txt for a example.



    cs89x0_dma=    [HW,NET]

            Format: <dma>



    cs89x0_media=    [HW,NET]

            Format: { rj45 | aui | bnc }



    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/joystick-parport.txt



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



    debug_locks_verbose=

            [KNL] verbose self-tests

            Format=<0|1>

            Print debugging info while doing the locking API

            self-tests.

            We default to 0 (no extra messages), setting it to

            1 will print _a lot_ more information - normally

            only useful to kernel developers.



    debug_objects    [KNL] Enable object debugging



    no_debug_objects

            [KNL] Disable object debugging



    debugpat    [X86] Enable PAT debugging



    decnet.addr=    [HW,NET]

            Format: <area>[,<node>]

            See also Documentation/networking/decnet.txt.



    default_hugepagesz=

            [same as hugepagesz=] The size of the default

            HugeTLB page size. This is the size represented by

            the legacy /proc/ hugepages APIs, used for SHM, and

            default size when mounting hugetlbfs filesystems.

            Defaults to the default architecture's huge page size

            if not specified.



    dhash_entries=    [KNL]

            Set number of hash buckets for dentry cache.



    digi=        [HW,SERIAL]

            IO parameters + enable/disable command.



    digiepca=    [HW,SERIAL]

            See drivers/char/README.epca and

            Documentation/serial/digiepca.txt.



    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.



    dmasound=    [HW,OSS] Sound subsystem buffers



    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.



    dscc4.setup=    [NET]



    dtc3181e=    [HW,SCSI]



    dynamic_printk    Enables pr_debug()/dev_dbg() calls if

            CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.

            These can also be switched on/off via

            <debugfs>/dynamic_printk/modules



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

        uart[8250],io,<addr>[,options]

        uart[8250],mmio,<addr>[,options]

            Start an early, polled-mode console on the 8250/16550

            UART at the specified I/O port or MMIO address.

            The options are the same as for ttyS, above.



    earlyprintk=    [X86,SH,BLACKFIN]

            earlyprintk=vga

            earlyprintk=serial[,ttySn[,baudrate]]

            earlyprintk=ttySn[,baudrate]

            earlyprintk=dbgp[debugController#]



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

            takes over.



            Only vga or serial or usb debug port at a time.



            Currently only ttyS0 and ttyS1 are supported.



            Interaction with the standard serial driver is not

            very good.



            The VGA output is eventually overwritten by the real

            console.



    eata=        [HW,SCSI]



    edd=        [EDD]

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



    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.



    elevator=    [IOSCHED]

            Format: {"anticipatory" | "cfq" | "deadline" | "noop"}

            See Documentation/block/as-iosched.txt and

            Documentation/block/deadline-iosched.txt for details.



    elfcorehdr=    [IA64,PPC,SH,X86]

            Specifies physical address of start of kernel core

            image elf header. Generally kexec loader will

            pass this option to capture kernel.

            See Documentation/kdump/kdump.txt 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 /selinux/enforce.



    ether=        [HW,NET] Ethernet cards parameters

            This option is obsoleted by the "netdev=" option, which

            has equivalent usage. See its documentation for details.



    eurwdt=        [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.

            Format: <io>[,<irq>]



    failslab=

    fail_page_alloc=

    fail_make_request=[KNL]

            General fault injection mechanism.

            Format: <interval>,<probability>,<space>,<times>

            See also /Documentation/fault-injection/.



    fd_mcs=        [HW,SCSI]

            See header of drivers/scsi/fd_mcs.c.



    fdomain=    [HW,SCSI]

            See header of drivers/scsi/fdomain.c.



    floppy=        [HW]

            See Documentation/blockdev/floppy.txt.



    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.



    ftrace=[tracer]

            [FTRACE] will set and start the specified tracer

            as early as possible in order to facilitate early

            boot debugging.



    ftrace_dump_on_oops

            [FTRACE] will dump the trace buffers on 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.



    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/joystick-parport.txt



    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.



    gdth=        [HW,SCSI]

            See header of drivers/scsi/gdth.c.



    gpt        [EFI] Forces disk with valid GPT signature but

            invalid Protective MBR to be treated as GPT.



    gvp11=        [HW,SCSI]



    hashdist=    [KNL,NUMA] Large hashes allocated during boot

            are distributed across NUMA nodes.  Defaults on

            for 64bit 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>



    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"



    hisax=        [HW,ISDN]

            See Documentation/isdn/README.HiSax.



    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



    hugepages=    [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.

    hugepagesz=    [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.

            On x86-64 and powerpc, this option can be specified

            multiple times interleaved with hugepages= to reserve

            huge pages of different sizes. Valid pages sizes on

            x86-64 are 2M (when the CPU supports "pse") and 1G

            (when the CPU supports the "pdpe1gb" cpuinfo flag)

            Note that 1GB pages can only be allocated at boot time

            using hugepages= and not freed afterwards.



    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.



    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.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.panicblink=

            [HW] Frequency with which keyboard LEDs should blink

                 when kernel panics (default is 0.5 sec)

    i8042.reset    [HW] Reset the controller during init and cleanup

    i8042.unlock    [HW] Unlock (ignore) the keylock



    i810=        [HW,DRM]



    i8k.ignore_dmi    [HW] Continue probing hardware even if DMI data

            indicates that the driver is running on unsupported

            hardware.

    i8k.force    [HW] Activate i8k driver even if SMM BIOS signature

            does not match list of supported models.

    i8k.power_status

            [HW] Report power status in /proc/i8k

            (disabled by default)

    i8k.restricted    [HW] Allow controlling fans only if SYS_ADMIN

            capability is set.



    ibmmcascsi=    [HW,MCA,SCSI] IBM MicroChannel SCSI adapter

            See Documentation/mca.txt.



    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.txt.



    ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem

            Claim all unknown PCI IDE storage controllers.



    idle=        [X86]

            Format: idle=poll, idle=mwait, 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=mwait: On systems which support MONITOR/MWAIT but

            the kernel chose to not use it because it doesn't save

            as much power as a normal idle loop, use the

            MONITOR/MWAIT idle loop anyways. Performance should be

            the same as idle=poll.

            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



    ignore_loglevel    [KNL]

            Ignore loglevel setting - this will print /all/

            kernel messages to the console. Useful for debugging.



    ihash_entries=    [KNL]

            Set number of hash buckets for inode cache.



    ima_audit=    [IMA]

            Format: { "0" | "1" }

            0 -- integrity auditing messages. (Default)

            1 -- enable informational integrity auditing messages.



    ima_hash=    [IMA]

            Format: { "sha1" | "md5" }

            default: "sha1"



    ima_tcb        [IMA]

            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.



    in2000=        [HW,SCSI]

            See header of drivers/scsi/in2000.c.



    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.



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



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

            Format: <irq>



    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.

        forcedac [x86_64]

            With this option iommu will not optimize to look

            for io virtual address below 32 bit forcing dual

            address cycle on pci bus for cards supporting greater

            than 32 bit addressing. The default is to look

            for translation below 32 bit and if not available

            then look in the higher range.

        strict [Default Off]

            With this option on every unmap_single operation will

            result in a hardware IOTLB flush operation as opposed

            to batching them for performance.



    inttest=    [IA64]



    iomem=        Disable strict checking of access to MMIO memory

        strict    regions from userspace.

        relaxed



    iommu=        [x86]

        off

        force

        noforce

        biomerge

        panic

        nopanic

        merge

        nomerge

        forcesac

        soft

        pt    [x86, IA64]



    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/filesystems/nfsroot.txt.



    ip2=        [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards

            See comment before ip2_setup() in

            drivers/char/ip2/ip2base.c.



    ips=        [HW,SCSI] Adaptec / IBM ServeRAID controller

            See header of drivers/scsi/ips.c.



    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] Isolate CPUs from the general scheduler.

            Format:

            <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>



            This option can be used to specify one or more CPUs

            to isolate from the general SMP balancing and scheduling

            algorithms. 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".



            This option is the preferred way to isolate CPUs. The

            alternative -- manually setting the CPU mask of all

            tasks in the system -- can cause problems and

            suboptimal load balancer performance.



    iucv=        [HW,NET]



    js=        [HW,JOY] Analog joystick

            See Documentation/input/joystick.txt.



    keepinitrd    [HW,ARM]



    kernelcore=nn[KMG]    [KNL,X86,IA-64,PPC] 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. The

            remaining memory in each node is used for Movable

            pages. In the event, a node is too small to have both

            kernelcore and Movable pages, kernelcore pages will

            take priority and other nodes will have a larger number

            of kernelcore pages.  The Movable zone is used for the

            allocation of pages that may be reclaimed or moved

            by the page migration subsystem.  This means that

            HugeTLB pages may not be allocated from this zone.

            Note that allocations like PTEs-from-HighMem still

            use the HighMem zone if it exists, and the Normal

            zone if it does not.



    kgdboc=        [HW] kgdb over consoles.

            Requires a tty driver that supports console polling.

            (only serial supported for now)

            Format: <serial_device>[,baud]



    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



    kstack=N    [X86] Print N words from the kernel stack

            in oops dumps.



    kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.

            Default is 0 (don't ignore, but inject #GP)



    kvm.oos_shadow=    [KVM] Disable out-of-sync shadow paging.

            Default is 1 (enabled)



    kvm-amd.nested=    [KVM,AMD] Allow nested virtualization in KVM/SVM.

            Default is 0 (off)



    kvm-amd.npt=    [KVM,AMD] Disable nested paging (virtualized MMU)

            for all guests.

            Default is 1 (enabled) if in 64bit or 32bit-PAE mode



    kvm-intel.bypass_guest_pf=

            [KVM,Intel] Disables bypassing of guest page faults

            on Intel chips. Default is 1 (enabled)



    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] Enable emulation of invalid guest states

            Default is 0 (disabled)



    kvm-intel.flexpriority=

            [KVM,Intel] Disable FlexPriority feature (TPR shadow).

            Default is 1 (enabled)



    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.vpid=    [KVM,Intel] Disable Virtual Processor Identification

            feature (tagged TLBs) on capable Intel chips.

            Default is 1 (enabled)



    l2cr=        [PPC]



    l3cr=        [PPC]



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

            disabled it.



    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.



            * nohrst, nosrst, norst: suppress hard, soft

                          and both resets.



            If there are multiple matching configurations changing

            the same attribute, the last one is used.



    lmb=debug    [KNL] Enable lmb debug messages.



    load_ramdisk=    [RAM] List of ramdisks to load from floppy

            See Documentation/blockdev/ramdisk.txt.



    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>



    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    Sets the size of the printk ring buffer, in bytes.

            Format: { n | nk | nM }

            n must be a power of two.  The default size

            is set in the kernel config file.



    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>



    mac5380=    [HW,SCSI] Format:

            <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>



    machvec=    [IA64] Force the use of a particular machine-vector

            (machvec) in a generic kernel.

            Example: machvec=hpzx1_swiotlb



    machtype=    [Loongson] Share the same kernel image file between different

             yeeloong laptop.

            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

            should make use of.  maxcpus=n : n >= 0 limits the

            kernel to using 'n' processors.  n=0 is a special case,

            it is equivalent to "nosmp", which also disables

            the IO APIC.



    max_loop=    [LOOP] Maximum number of loopback devices that can

            be mounted

            Format: <1-256>



    max_luns=    [SCSI] Maximum number of LUNs to probe.

            Should be between 1 and 2^32-1.



    max_report_luns=

            [SCSI] Maximum number of LUNs received.

            Should be between 1 and 16384.



    mcatest=    [IA-64]



    mce        [X86-32] Machine Check Exception



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



    md=        [HW] RAID subsystems devices and level

            See Documentation/md.txt.



    mdacon=        [MDA]

            Format: <first>,<last>

            Specifies range of consoles to be captured by the MDA.



    mem=nn[KMG]    [KNL,BOOT] Force usage of a specific amount of memory

            Amount of memory to be used when the kernel is not able

            to see the whole system memory or for test.

            [X86-32] Use together with memmap= to avoid physical

            address space collisions. Without memmap= PCI devices

            could be placed at addresses belonging to unused RAM.



    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.



    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] Force usage of a specific region of memory

            Region of memory to be used, from ss to ss+nn.



    memmap=nn[KMG]#ss[KMG]

            [KNL,ACPI] Mark specific memory as ACPI data.

            Region of memory to be used, from ss to ss+nn.



    memmap=nn[KMG]$ss[KMG]

            [KNL,ACPI] Mark specific memory as reserved.

            Region of memory to be used, from ss to ss+nn.

            Example: Exclude memory from 0x18690000-0x1869ffff

                     memmap=64K$0x18690000

                     or

                     memmap=0x10000$0x18690000



    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.



    memtest=    [KNL,X86] 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.



    meye.*=        [HW] Set MotionEye Camera parameters

            See Documentation/video4linux/meye.txt.



    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

            http://repo.or.cz/w/linux-2.6/mini2440.git



    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.



    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=nn[KMG]    [KNL,X86,IA-64,PPC] This parameter

            is similar to kernelcore except 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.



    mpu401=        [HW,OSS]

            Format: <io>,<irq>



    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/cmdlinepart.c.



    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-s3c2412/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



    NCR_D700=    [HW,SCSI]

            See header of drivers/scsi/NCR_D700.c.



    ncr5380=    [HW,SCSI]



    ncr53c400=    [HW,SCSI]



    ncr53c400a=    [HW,SCSI]



    ncr53c406a=    [HW,SCSI]



    ncr53c8xx=    [HW,SCSI]



    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 depends on CONFIG_NF_CT_ACCT that is

            going to be removed in 2.6.29.



    nfsaddrs=    [NFS]

            See Documentation/filesystems/nfsroot.txt.



    nfsroot=    [NFS] nfs root filesystem for disk-less boxes.

            See Documentation/filesystems/nfsroot.txt.



    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.



    nmi_debug=    [KNL,AVR32,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,][num]

            Valid num: 0,1,2

            0 - turn nmi_watchdog off

            1 - use the IO-APIC timer for the NMI watchdog

            2 - use the local APIC for the NMI watchdog using

            a performance counter. Note: This will use one

            performance counter and the local APIC's performance

            vector.

            When panic is specified, panic when an NMI watchdog

            timeout occurs.

            This is useful when you use a panic=... timeout and

            need the box quickly up again.

            Instead of 1 and 2 it is possible to use the following

            symbolic names: lapic and ioapic

            Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic



    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.



    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.



    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]



    noapic        [SMP,APIC] Tells the kernel to not make use of any

            IOAPICs that may be present in the system.



    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



    nodelayacct    [KNL] Disable per-task delay accounting



    nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.



    nodsp        [SH] Disable hardware DSP at boot time.



    noefi        [X86] Disable EFI runtime services support.



    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



    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        [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.



    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.



    nohlt        [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or

            wfi(ARM) instruction doesn't work correctly and not to

            use it. This is also useful when using JTAG debugger.



    no-hlt        [BUGS=X86-32] Tells the kernel that the hlt

            instruction doesn't work correctly and not to

            use it.



    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.



    nohz=        [KNL] Boottime enable/disable dynamic ticks

            Valid arguments: on, off

            Default: on



    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.



    nointroute    [IA-64]



    nojitter    [IA64] Disables jitter checking for ITC timers.



    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.



    nomca        [IA-64] Disable machine check abort handling



    nomce        [X86-32] Machine Check Exception



    nomfgpt        [X86-32] Disable Multi-Function General Purpose

            Timer usage (for AMD Geode machines).



    norandmaps    Don't use address space randomization.  Equivalent to

            echo 0 > /proc/sys/kernel/randomize_va_space



    noreplace-paravirt    [X86-32,PV_OPS] Don't patch paravirt_ops



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

            with UP alternatives



    noresidual    [PPC] Don't use residual data on PReP machines.



    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.



    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.



    noswapaccount    [KNL] Disable accounting of swap in memory resource

            controller. (See Documentation/cgroups/memory.txt)



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



    notsc        [BUGS=X86-32] Disable Time Stamp Counter



    nousb        [USB] Disable the USB subsystem



    nowb        [ARM]



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



    nptcg=        [IA64] Override max number of concurrent global TLB

            purges which is reported from either PAL_VM_SUMMARY or

            SAL PALO.



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



    numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.

            one of ['zone', 'node', 'default'] can be specified

            This can be set from sysctl after boot.

            See Documentation/sysctl/vm.txt for details.



    ohci1394_dma=early    [HW] enable debugging via the ohci1394 driver.

            See Documentation/debugging-via-ohci1394.txt 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!



    opl3=        [HW,OSS]

            Format: <io>



    oprofile.timer=    [HW]

            Use timer interrupt instead of performance counters



    oprofile.cpu_type=    Force an oprofile cpu type

            This might be useful if you have an older oprofile

            userland or if you want common events.

            Format: { arch_perfmon }

            arch_perfmon: [X86] Force use of architectural

                perfmon on Intel CPUs instead of the

                CPU specific event set.



    osst=        [HW,SCSI] SCSI Tape Driver

            Format: <buffer_size>,<write_threshold>

            See also Documentation/scsi/st.txt.



    panic=        [KNL] Kernel behaviour on panic

            Format: <timeout>



    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]



    pas2=        [HW,OSS] Format:

            <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>



    pas16=        [HW,SCSI]

            See header of drivers/scsi/pas16.c.



    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/blockdev/paride.txt.



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

        earlydump    [X86] 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

                Mechanism 1.

        conf2        [X86] Force use of PCI Configuration

                Mechanism 2.

        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.

        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 _CRS for PCI resource

                allocation.

        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

        firmware    [ARM] Do not re-enumerate the bus but instead

                just use the configuration from the

                bootloader. This is currently used on

                IXP2000 systems where the bus has to be

                configured a certain way for adjunct CPUs.

        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.

        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>@][<domain>:]<bus>:<slot>.<func>[; ...]

                Specifies alignment and device to reassign

                aligned memory resources.

                If <order of align> is not specified,

                PAGE_SIZE is used as alignment.

                PCI-PCI bridge can be specified, if resource

                windows need to be expanded.

        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.



    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.



    pcmv=        [HW,PCMCIA] BadgePAD 4



    pd.        [PARIDE]

            See Documentation/blockdev/paride.txt.



    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/blockdev/paride.txt.



    pg.        [PARIDE]

            See Documentation/blockdev/paride.txt.



    pirq=        [SMP,APIC] Manual mp-table setup

            See Documentation/x86/i386/IO-APIC.txt.



    plip=        [PPT,NET] Parallel port network link

            Format: { parport<nr> | timid | 0 }

            See also Documentation/parport.txt.



    pmtmr=        [X86] Manual setup of pmtmr I/O Port. 

            Override pmtimer IOPort with a hex value.

            e.g. pmtmr=0x508



    pnp.debug    [PNP]

            Enable PNP debug messages.  This depends on the

            CONFIG_PNP_DEBUG_MESSAGES option.



    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>....



    print-fatal-signals=

            [KNL] debug: print fatal signals

            print-fatal-signals=1: print segfault info to

            the kernel console.

            default: off.



    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: [schedule,]<number>

            Param: "schedule" - profile schedule points.

            Param: <number> - step/bucket size as a power of 2 for

                statistical time based profiling.

            Param: "sleep" - profile D-state sleeping (millisecs).

                Requires CONFIG_SCHEDSTATS

            Param: "kvm" - profile VM exits.



    prompt_ramdisk=    [RAM] List of RAM disks to prompt for floppy disk

            before loading.

            See Documentation/blockdev/ramdisk.txt.



    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).



    pss=        [HW,OSS] Personal Sound System (ECHO ESC614)

            Format:

            <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>



    pt.        [PARIDE]

            See Documentation/blockdev/paride.txt.



    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/md.txt.



    ramdisk_blocksize=    [RAM]

            See Documentation/blockdev/ramdisk.txt.



    ramdisk_size=    [RAM] Sizes of RAM disks in kilobytes

            See Documentation/blockdev/ramdisk.txt.



    rcupdate.blimit=    [KNL,BOOT]

            Set maximum number of finished RCU callbacks to process

            in one batch.



    rcupdate.qhimark=    [KNL,BOOT]

            Set threshold of queued

            RCU callbacks over which batch limiting is disabled.



    rcupdate.qlowmark=    [KNL,BOOT]

            Set threshold of queued RCU callbacks below which

            batch limiting is re-enabled.



    rdinit=        [KNL]

            Format: <full_path>

            Run specified binary instead of /init from the ramdisk,

            used for early userspace startup. See initrd.



    reboot=        [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode

            Format: <reboot_mode>[,<reboot_mode2>[,...]]

            See arch/*/kernel/reboot.c or arch/*/kernel/process.c



    relax_domain_level=

            [KNL, SMP] Set scheduler's default relax_domain_level.

            See Documentation/cgroups/cpusets.txt.



    reserve=    [KNL,BUGS] Force the kernel to ignore some iomem area



    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



    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.txt



    retain_initrd    [RAM] Keep initrd memory after extraction



    rhash_entries=    [KNL,NET]

            Set number of hash buckets for route cache



    riscom8=    [HW,SERIAL]

            Format: <io_board1>[,<io_board2>[,...<io_boardN>]]



    ro        [KNL] Mount root device read-only on boot



    root=        [KNL] Root filesystem



    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).



    root_plug.vendor_id=

            [ROOTPLUG] Override the default vendor ID



    root_plug.product_id=

            [ROOTPLUG] Override the default product ID



    root_plug.debug=

            [ROOTPLUG] Enable debugging output



    rw        [KNL] Mount root device read-write on boot



    S        [KNL] Run init in single mode



    sa1100ir    [NET]

            See drivers/net/irda/sa1100_ir.c.



    sbni=        [NET] Granch SBNI12 leased line adapter



    sc1200wdt=    [HW,WDT] SC1200 WDT (watchdog) driver

            Format: <io>[,<timeout>[,<isapnp>]]



    scsi_debug_*=    [SCSI]

            See drivers/scsi/scsi_debug.c.



    scsi_default_dev_flags=

            [SCSI] SCSI default device flags

            Format: <integer>



    scsi_dev_flags=    [SCSI] Black/white list entry for vendor and model

            Format: <vendor>:<model>:<flags>

            (flags are integer value)



    scsi_logging_level=    [SCSI] a bit mask of logging levels

            See drivers/scsi/scsi_logging.h for bits.  Also

            settable via sysctl at dev.scsi.logging_level

            (/proc/sys/dev/scsi/logging_level).

            There is also a nice 'scsi_logging_level' script in the

            S390-tools package, available for download at

            http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html



    scsi_mod.scan=    [SCSI] sync (default) scans SCSI busses as they are

            discovered.  async scans them in kernel threads,

            allowing boot to proceed.  none ignores them, expecting

            user space to do the scan.



    security=    [SECURITY] Choose a security module to enable at boot.

            If this boot parameter is not specified, only the first

            security module asking for security registration will be

            loaded. An invalid security module name will be treated

            as if no module has been chosen.



    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 set via kernel config option.

            If enabled at boot time, /selinux/disable can be used

            later to disable prior to initial policy load.



    serialnumber    [BUGS=X86-32]



    shapers=    [NET]

            Maximal number of shapers.



    show_msr=    [x86] show boot-time MSR settings

            Format: { <integer> }

            Show boot-time (BIOS-initialized) MSR settings.

            The parameter means the number of CPUs to show,

            for example 1 means boot CPU only.



    sim710=        [SCSI,HW]

            See header of drivers/scsi/sim710.c.



    simeth=        [IA-64]

    simscsi=



    slram=        [HW,MTD]



    slub_debug[=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.txt.



    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.txt.



    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.txt.



    slub_min_order=    [MM, SLUB]

            Determines the mininum page order for slabs. Must be

            lower than slub_max_order.

            For more information see Documentation/vm/slub.txt.



    slub_nomerge    [MM, SLUB]

            Disable merging of slabs with similar size. May be

            necessary if there is some reason to distinguish

            allocs to different slabs. Debug options disable

            merging on their own.

            For more information see Documentation/vm/slub.txt.



    smart2=        [HW]

            Format: <io1>[,<io2>[,...,<io8>]]



    smp-alt-once    [X86-32,SMP] On a hotplug CPU system, only

            attempt to substitute SMP alternatives once at boot.



    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



    snd-ad1816a=    [HW,ALSA]



    snd-ad1848=    [HW,ALSA]



    snd-ali5451=    [HW,ALSA]



    snd-als100=    [HW,ALSA]



    snd-als4000=    [HW,ALSA]



    snd-azt2320=    [HW,ALSA]



    snd-cmi8330=    [HW,ALSA]



    snd-cmipci=    [HW,ALSA]



    snd-cs4231=    [HW,ALSA]



    snd-cs4232=    [HW,ALSA]



    snd-cs4236=    [HW,ALSA]



    snd-cs4281=    [HW,ALSA]



    snd-cs46xx=    [HW,ALSA]



    snd-dt019x=    [HW,ALSA]



    snd-dummy=    [HW,ALSA]



    snd-emu10k1=    [HW,ALSA]



    snd-ens1370=    [HW,ALSA]



    snd-ens1371=    [HW,ALSA]



    snd-es968=    [HW,ALSA]



    snd-es1688=    [HW,ALSA]



    snd-es18xx=    [HW,ALSA]



    snd-es1938=    [HW,ALSA]



    snd-es1968=    [HW,ALSA]



    snd-fm801=    [HW,ALSA]



    snd-gusclassic=    [HW,ALSA]



    snd-gusextreme=    [HW,ALSA]



    snd-gusmax=    [HW,ALSA]



    snd-hdsp=    [HW,ALSA]



    snd-ice1712=    [HW,ALSA]



    snd-intel8x0=    [HW,ALSA]



    snd-interwave=    [HW,ALSA]



    snd-interwave-stb=

            [HW,ALSA]



    snd-korg1212=    [HW,ALSA]



    snd-maestro3=    [HW,ALSA]



    snd-mpu401=    [HW,ALSA]



    snd-mtpav=    [HW,ALSA]



    snd-nm256=    [HW,ALSA]



    snd-opl3sa2=    [HW,ALSA]



    snd-opti92x-ad1848=

            [HW,ALSA]



    snd-opti92x-cs4231=

            [HW,ALSA]



    snd-opti93x=    [HW,ALSA]



    snd-pmac=    [HW,ALSA]



    snd-rme32=    [HW,ALSA]



    snd-rme96=    [HW,ALSA]



    snd-rme9652=    [HW,ALSA]



    snd-sb8=    [HW,ALSA]



    snd-sb16=    [HW,ALSA]



    snd-sbawe=    [HW,ALSA]



    snd-serial=    [HW,ALSA]



    snd-sgalaxy=    [HW,ALSA]



    snd-sonicvibes=    [HW,ALSA]



    snd-sun-amd7930=

            [HW,ALSA]



    snd-sun-cs4231=    [HW,ALSA]



    snd-trident=    [HW,ALSA]



    snd-usb-audio=    [HW,ALSA,USB]



    snd-via82xx=    [HW,ALSA]



    snd-virmidi=    [HW,ALSA]



    snd-wavefront=    [HW,ALSA]



    snd-ymfpci=    [HW,ALSA]



    softlockup_panic=

            [KNL] Should the soft-lockup detector generate panics.



    sonypi.*=    [HW] Sony Programmable I/O Control Device driver

            See Documentation/sonypi.txt



    specialix=    [HW,SERIAL] Specialix multi-serial port adapter

            See Documentation/serial/specialix.txt.



    spia_io_base=    [HW,MTD]

    spia_fio_base=

    spia_pedr=

    spia_peddr=



    sscape=        [HW,OSS]

            Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>



    st=        [HW,SCSI] SCSI tape parameters (buffers, etc.)

            See Documentation/scsi/st.txt.



    stacktrace    [FTRACE]

            Enabled the stack tracer on boot up.



    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>...]]



    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.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.



    swiotlb=    [IA-64] Number of I/O TLB slabs



    switches=    [HW,M68k]



    sym53c416=    [HW,SCSI]

            See header of drivers/scsi/sym53c416.c.



    sysrq_always_enabled

            [KNL]

            Ignore sysrq setting - this boot parameter will

            neutralize any effect of /proc/sys/kernel/sysrq.

            Useful for debugging.



    t128=        [HW,SCSI]

            See header of drivers/scsi/t128.c.



    tdfx=        [HW,DRM]



    test_suspend=    [SUSPEND]

            Specify "mem" (for Suspend-to-RAM) or "standby" (for

            standby suspend) as the system sleep state to briefly

            enter during system startup.  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)



    tmscsim=    [HW,SCSI]

            See comment before function dc390_setup() in

            drivers/scsi/tmscsim.c.



    topology=    [S390]

            Format: {off | on}

            Specify if the kernel should make use of the cpu

            topology informations if the hardware supports these.

            The scheduler will make use of these informations and

            e.g. base its process migration decisions on it.

            Default is off.



    tp720=        [HW,PS2]



    trace_buf_size=nn[KMG]

            [FTRACE] will set tracing buffer size.



    trace_event=[event-list]

            [FTRACE] Set and start specified trace events in order

            to facilitate early boot debugging.

            See also Documentation/trace/events.txt



    trix=        [HW,OSS] MediaTrix AudioTrix Pro

            Format:

            <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>



    tsc=        Disable clocksource-must-verify flag for TSC.

            Format: <string>

            [x86] reliable: mark tsc clocksource as reliable, this

            disables clocksource verification at runtime.

            Used to enable high-resolution timer mode on older

            hardware, and in virtualized environment.



    turbografx.map[2|3]=    [HW,JOY]

            TurboGraFX parallel port interface

            Format:

            <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>

            See also Documentation/input/joystick-parport.txt



    u14-34f=    [HW,SCSI] UltraStor 14F/34F SCSI host adapter

            See header of drivers/scsi/u14-34f.c.



    uart401=    [HW,OSS]

            Format: <io>,<irq>



    uart6850=    [HW,OSS]

            Format: <io>,<irq>



    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]

            Set unknown_nmi_panic=1 early on boot.



    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.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.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).



    usbhid.mousepoll=

            [USBHID] The interval which mice are to be polled at.



    usb-storage.delay_use=

            [UMS] The delay in seconds before a new device is

            scanned for Logical Units (default 5).



    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);

                c = FIX_CAPACITY (decrease the reported

                    device capacity by one sector);

                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);

                l = NOT_LOCKABLE (don't try to lock and

                    unlock ejectable media);

                m = MAX_SECTORS_64 (don't transfer more

                    than 64 sectors = 32 KB at a time);

                o = CAPACITY_OK (accept the capacity

                    reported by the device);

                r = IGNORE_RESIDUE (the device reports

                    bogus residue values);

                s = SINGLE_LUN (the device has only one

                    Logical Unit);

                w = NO_WP_DETECT (don't test whether the

                    medium is write-protected).

            Example: quirks=0419:aaf5:rl,0421:0433:rc



    vdso=        [X86,SH]

            vdso=2: enable compat VDSO (default with COMPAT_VDSO)

            vdso=1: enable VDSO (default)

            vdso=0: disable VDSO mapping



    vdso32=        [X86]

            vdso32=2: enable compat VDSO (default with COMPAT_VDSO)

            vdso32=1: enable 32-bit VDSO (default)

            vdso32=0: disable 32-bit VDSO mapping



    vector=        [IA-64,SMP]

            vector=percpu: enable percpu vector domain



    video=        [FB] Frame buffer configuration

            See Documentation/fb/modedb.txt.



    vga=        [BOOT,X86-32] Select a particular video mode

            See Documentation/x86/boot.txt and

            Documentation/svga.txt.

            Use vga=ask for menu.

            This is actually a boot loader parameter; the value is

            passed to the kernel using a special protocol.



    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.



    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>



    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.



    waveartist=    [HW,OSS]

            Format: <io>,<irq>,<dma>,<dma2>



    wd33c93=    [HW,SCSI]

            See header of drivers/scsi/wd33c93.c.



    wd7000=        [HW,SCSI]

            See header of drivers/scsi/wd7000.c.



    wdt=        [WDT] Watchdog

            See Documentation/watchdog/wdt.txt.



    x2apic_phys    [X86-64,APIC] Use x2apic physical mode instead of

            default x2apic cluster mode on platforms

            supporting x2apic.



    xd=        [HW,XT] Original XT pre-IDE (RLL encoded) disks.

    xd_geo=        See header of drivers/block/xd.c.



    xirc2ps_cs=    [NET,PCMCIA]

            Format:

            <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]



______________________________________________________________________



TODO:



    Add documentation for ALSA options.

    Add more DRM drivers.