linux/Documentation/kernel-parameters.txt
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   1                          Kernel Parameters
   2                          ~~~~~~~~~~~~~~~~~
   3
   4The following is a consolidated list of the kernel parameters as implemented
   5(mostly) by the __setup() macro and sorted into English Dictionary order
   6(defined as ignoring all punctuation and sorting digits before letters in a
   7case insensitive manner), and with descriptions where known.
   8
   9Module parameters for loadable modules are specified only as the
  10parameter name with optional '=' and value as appropriate, such as:
  11
  12        modprobe usbcore blinkenlights=1
  13
  14Module parameters for modules that are built into the kernel image
  15are specified on the kernel command line with the module name plus
  16'.' plus parameter name, with '=' and value if appropriate, such as:
  17
  18        usbcore.blinkenlights=1
  19
  20This document may not be entirely up to date and comprehensive. The command
  21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  22module. Loadable modules, after being loaded into the running kernel, also
  23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  24parameters may be changed at runtime by the command
  25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  26
  27The parameters listed below are only valid if certain kernel build options were
  28enabled and if respective hardware is present. The text in square brackets at
  29the beginning of each description states the restrictions within which a
  30parameter is applicable:
  31
  32        ACPI    ACPI support is enabled.
  33        AGP     AGP (Accelerated Graphics Port) is enabled.
  34        ALSA    ALSA sound support is enabled.
  35        APIC    APIC support is enabled.
  36        APM     Advanced Power Management support is enabled.
  37        AVR32   AVR32 architecture is enabled.
  38        AX25    Appropriate AX.25 support is enabled.
  39        BLACKFIN Blackfin architecture is enabled.
  40        DRM     Direct Rendering Management support is enabled.
  41        EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
  42        EFI     EFI Partitioning (GPT) is enabled
  43        EIDE    EIDE/ATAPI support is enabled.
  44        FB      The frame buffer device is enabled.
  45        HW      Appropriate hardware is enabled.
  46        IA-64   IA-64 architecture is enabled.
  47        IOSCHED More than one I/O scheduler is enabled.
  48        IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
  49        ISAPNP  ISA PnP code is enabled.
  50        ISDN    Appropriate ISDN support is enabled.
  51        JOY     Appropriate joystick support is enabled.
  52        LIBATA  Libata driver is enabled
  53        LP      Printer support is enabled.
  54        LOOP    Loopback device support is enabled.
  55        M68k    M68k architecture is enabled.
  56                        These options have more detailed description inside of
  57                        Documentation/m68k/kernel-options.txt.
  58        MCA     MCA bus support is enabled.
  59        MDA     MDA console support is enabled.
  60        MOUSE   Appropriate mouse support is enabled.
  61        MSI     Message Signaled Interrupts (PCI).
  62        MTD     MTD (Memory Technology Device) support is enabled.
  63        NET     Appropriate network support is enabled.
  64        NUMA    NUMA support is enabled.
  65        GENERIC_TIME The generic timeofday code is enabled.
  66        NFS     Appropriate NFS support is enabled.
  67        OSS     OSS sound support is enabled.
  68        PV_OPS  A paravirtualized kernel is enabled.
  69        PARIDE  The ParIDE (parallel port IDE) subsystem is enabled.
  70        PARISC  The PA-RISC architecture is enabled.
  71        PCI     PCI bus support is enabled.
  72        PCIE    PCI Express support is enabled.
  73        PCMCIA  The PCMCIA subsystem is enabled.
  74        PNP     Plug & Play support is enabled.
  75        PPC     PowerPC architecture is enabled.
  76        PPT     Parallel port support is enabled.
  77        PS2     Appropriate PS/2 support is enabled.
  78        RAM     RAM disk support is enabled.
  79        ROOTPLUG The example Root Plug LSM is enabled.
  80        S390    S390 architecture is enabled.
  81        SCSI    Appropriate SCSI support is enabled.
  82                        A lot of drivers has their options described inside of
  83                        Documentation/scsi/.
  84        SECURITY Different security models are enabled.
  85        SELINUX SELinux support is enabled.
  86        SERIAL  Serial support is enabled.
  87        SH      SuperH architecture is enabled.
  88        SMP     The kernel is an SMP kernel.
  89        SPARC   Sparc architecture is enabled.
  90        SWSUSP  Software suspend (hibernation) is enabled.
  91        SUSPEND System suspend states are enabled.
  92        TS      Appropriate touchscreen support is enabled.
  93        USB     USB support is enabled.
  94        USBHID  USB Human Interface Device support is enabled.
  95        V4L     Video For Linux support is enabled.
  96        VGA     The VGA console has been enabled.
  97        VT      Virtual terminal support is enabled.
  98        WDT     Watchdog support is enabled.
  99        XT      IBM PC/XT MFM hard disk support is enabled.
 100        X86-32  X86-32, aka i386 architecture is enabled.
 101        X86-64  X86-64 architecture is enabled.
 102                        More X86-64 boot options can be found in
 103                        Documentation/x86/x86_64/boot-options.txt .
 104        X86     Either 32bit or 64bit x86 (same as X86-32+X86-64)
 105
 106In addition, the following text indicates that the option:
 107
 108        BUGS=   Relates to possible processor bugs on the said processor.
 109        KNL     Is a kernel start-up parameter.
 110        BOOT    Is a boot loader parameter.
 111
 112Parameters denoted with BOOT are actually interpreted by the boot
 113loader, and have no meaning to the kernel directly.
 114Do not modify the syntax of boot loader parameters without extreme
 115need or coordination with <Documentation/x86/i386/boot.txt>.
 116
 117There are also arch-specific kernel-parameters not documented here.
 118See for example <Documentation/x86/x86_64/boot-options.txt>.
 119
 120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
 121a trailing = on the name of any parameter states that that parameter will
 122be entered as an environment variable, whereas its absence indicates that
 123it will appear as a kernel argument readable via /proc/cmdline by programs
 124running once the system is up.
 125
 126The number of kernel parameters is not limited, but the length of the
 127complete command line (parameters including spaces etc.) is limited to
 128a fixed number of characters. This limit depends on the architecture
 129and is between 256 and 4096 characters. It is defined in the file
 130./include/asm/setup.h as COMMAND_LINE_SIZE.
 131
 132
 133        acpi=           [HW,ACPI,X86-64,i386]
 134                        Advanced Configuration and Power Interface
 135                        Format: { force | off | ht | strict | noirq }
 136                        force -- enable ACPI if default was off
 137                        off -- disable ACPI if default was on
 138                        noirq -- do not use ACPI for IRQ routing
 139                        ht -- run only enough ACPI to enable Hyper Threading
 140                        strict -- Be less tolerant of platforms that are not
 141                                strictly ACPI specification compliant.
 142
 143                        See also Documentation/power/pm.txt, pci=noacpi
 144
 145        acpi_apic_instance=     [ACPI, IOAPIC]
 146                        Format: <int>
 147                        2: use 2nd APIC table, if available
 148                        1,0: use 1st APIC table
 149                        default: 0
 150
 151        acpi_sleep=     [HW,ACPI] Sleep options
 152                        Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
 153                        See Documentation/power/video.txt for s3_bios and s3_mode.
 154                        s3_beep is for debugging; it makes the PC's speaker beep
 155                        as soon as the kernel's real-mode entry point is called.
 156                        s4_nohwsig prevents ACPI hardware signature from being
 157                        used during resume from hibernation.
 158                        old_ordering causes the ACPI 1.0 ordering of the _PTS
 159                        control method, wrt putting devices into low power
 160                        states, to be enforced (the ACPI 2.0 ordering of _PTS is
 161                        used by default).
 162
 163        acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 164                        Format: { level | edge | high | low }
 165
 166        acpi_irq_balance [HW,ACPI]
 167                        ACPI will balance active IRQs
 168                        default in APIC mode
 169
 170        acpi_irq_nobalance [HW,ACPI]
 171                        ACPI will not move active IRQs (default)
 172                        default in PIC mode
 173
 174        acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
 175                        use by PCI
 176                        Format: <irq>,<irq>...
 177
 178        acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
 179                        Format: <irq>,<irq>...
 180
 181        acpi_no_auto_ssdt       [HW,ACPI] Disable automatic loading of SSDT
 182
 183        acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
 184                        Format: To spoof as Windows 98: ="Microsoft Windows"
 185
 186        acpi_osi=       [HW,ACPI] Modify list of supported OS interface strings
 187                        acpi_osi="string1"      # add string1 -- only one string
 188                        acpi_osi="!string2"     # remove built-in string2
 189                        acpi_osi=               # disable all strings
 190
 191        acpi_serialize  [HW,ACPI] force serialization of AML methods
 192
 193        acpi_skip_timer_override [HW,ACPI]
 194                        Recognize and ignore IRQ0/pin2 Interrupt Override.
 195                        For broken nForce2 BIOS resulting in XT-PIC timer.
 196        acpi_use_timer_override [HW,ACPI}
 197                        Use timer override. For some broken Nvidia NF5 boards
 198                        that require a timer override, but don't have
 199                        HPET
 200
 201        acpi_backlight= [HW,ACPI]
 202                        acpi_backlight=vendor
 203                        acpi_backlight=video
 204                        If set to vendor, prefer vendor specific driver
 205                        (e.g. thinkpad_acpi, sony_acpi, etc.) instead
 206                        of the ACPI video.ko driver.
 207
 208        acpi_display_output=    [HW,ACPI]
 209                        acpi_display_output=vendor
 210                        acpi_display_output=video
 211                        See above.
 212
 213        acpi.debug_layer=       [HW,ACPI,ACPI_DEBUG]
 214        acpi.debug_level=       [HW,ACPI,ACPI_DEBUG]
 215                        Format: <int>
 216                        CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
 217                        debug output.  Bits in debug_layer correspond to a
 218                        _COMPONENT in an ACPI source file, e.g.,
 219                            #define _COMPONENT ACPI_PCI_COMPONENT
 220                        Bits in debug_level correspond to a level in
 221                        ACPI_DEBUG_PRINT statements, e.g.,
 222                            ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
 223                        The debug_level mask defaults to "info".  See
 224                        Documentation/acpi/debug.txt for more information about
 225                        debug layers and levels.
 226
 227                        Enable processor driver info messages:
 228                            acpi.debug_layer=0x20000000
 229                        Enable PCI/PCI interrupt routing info messages:
 230                            acpi.debug_layer=0x400000
 231                        Enable AML "Debug" output, i.e., stores to the Debug
 232                        object while interpreting AML:
 233                            acpi.debug_layer=0xffffffff acpi.debug_level=0x2
 234                        Enable all messages related to ACPI hardware:
 235                            acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
 236
 237                        Some values produce so much output that the system is
 238                        unusable.  The "log_buf_len" parameter may be useful
 239                        if you need to capture more output.
 240
 241        acpi.power_nocheck=     [HW,ACPI]
 242                        Format: 1/0 enable/disable the check of power state.
 243                        On some bogus BIOS the _PSC object/_STA object of
 244                        power resource can't return the correct device power
 245                        state. In such case it is unneccessary to check its
 246                        power state again in power transition.
 247                        1 : disable the power state check
 248
 249        acpi_pm_good    [X86-32,X86-64]
 250                        Override the pmtimer bug detection: force the kernel
 251                        to assume that this machine's pmtimer latches its value
 252                        and always returns good values.
 253
 254        agp=            [AGP]
 255                        { off | try_unsupported }
 256                        off: disable AGP support
 257                        try_unsupported: try to drive unsupported chipsets
 258                                (may crash computer or cause data corruption)
 259
 260        enable_timer_pin_1 [i386,x86-64]
 261                        Enable PIN 1 of APIC timer
 262                        Can be useful to work around chipset bugs
 263                        (in particular on some ATI chipsets).
 264                        The kernel tries to set a reasonable default.
 265
 266        disable_timer_pin_1 [i386,x86-64]
 267                        Disable PIN 1 of APIC timer
 268                        Can be useful to work around chipset bugs.
 269
 270        ad1848=         [HW,OSS]
 271                        Format: <io>,<irq>,<dma>,<dma2>,<type>
 272
 273        advansys=       [HW,SCSI]
 274                        See header of drivers/scsi/advansys.c.
 275
 276        advwdt=         [HW,WDT] Advantech WDT
 277                        Format: <iostart>,<iostop>
 278
 279        aedsp16=        [HW,OSS] Audio Excel DSP 16
 280                        Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 281                        See also header of sound/oss/aedsp16.c.
 282
 283        aha152x=        [HW,SCSI]
 284                        See Documentation/scsi/aha152x.txt.
 285
 286        aha1542=        [HW,SCSI]
 287                        Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 288
 289        aic7xxx=        [HW,SCSI]
 290                        See Documentation/scsi/aic7xxx.txt.
 291
 292        aic79xx=        [HW,SCSI]
 293                        See Documentation/scsi/aic79xx.txt.
 294
 295        amd_iommu=      [HW,X86-84]
 296                        Pass parameters to the AMD IOMMU driver in the system.
 297                        Possible values are:
 298                        isolate - enable device isolation (each device, as far
 299                                  as possible, will get its own protection
 300                                  domain) [default]
 301                        share - put every device behind one IOMMU into the
 302                                same protection domain
 303                        fullflush - enable flushing of IO/TLB entries when
 304                                    they are unmapped. Otherwise they are
 305                                    flushed before they will be reused, which
 306                                    is a lot of faster
 307
 308        amd_iommu_size= [HW,X86-64]
 309                        Define the size of the aperture for the AMD IOMMU
 310                        driver. Possible values are:
 311                        '32M', '64M' (default), '128M', '256M', '512M', '1G'
 312
 313        amijoy.map=     [HW,JOY] Amiga joystick support
 314                        Map of devices attached to JOY0DAT and JOY1DAT
 315                        Format: <a>,<b>
 316                        See also Documentation/kernel/input/joystick.txt
 317
 318        analog.map=     [HW,JOY] Analog joystick and gamepad support
 319                        Specifies type or capabilities of an analog joystick
 320                        connected to one of 16 gameports
 321                        Format: <type1>,<type2>,..<type16>
 322
 323        apc=            [HW,SPARC]
 324                        Power management functions (SPARCstation-4/5 + deriv.)
 325                        Format: noidle
 326                        Disable APC CPU standby support. SPARCstation-Fox does
 327                        not play well with APC CPU idle - disable it if you have
 328                        APC and your system crashes randomly.
 329
 330        apic=           [APIC,i386] Advanced Programmable Interrupt Controller
 331                        Change the output verbosity whilst booting
 332                        Format: { quiet (default) | verbose | debug }
 333                        Change the amount of debugging information output
 334                        when initialising the APIC and IO-APIC components.
 335
 336        apm=            [APM] Advanced Power Management
 337                        See header of arch/x86/kernel/apm_32.c.
 338
 339        arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 340                        Format: <io>,<irq>,<nodeID>
 341
 342        ataflop=        [HW,M68k]
 343
 344        atarimouse=     [HW,MOUSE] Atari Mouse
 345
 346        atascsi=        [HW,SCSI] Atari SCSI
 347
 348        atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 349                        EzKey and similar keyboards
 350
 351        atkbd.reset=    [HW] Reset keyboard during initialization
 352
 353        atkbd.set=      [HW] Select keyboard code set
 354                        Format: <int> (2 = AT (default), 3 = PS/2)
 355
 356        atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 357                        keyboards
 358
 359        atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 360                        Format: <bool> (0 = real, 1 = synthetic (default))
 361
 362        atkbd.softrepeat= [HW]
 363                        Use software keyboard repeat
 364
 365        autotest        [IA64]
 366
 367        baycom_epp=     [HW,AX25]
 368                        Format: <io>,<mode>
 369
 370        baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 371                        Format: <io>,<mode>
 372                        See header of drivers/net/hamradio/baycom_par.c.
 373
 374        baycom_ser_fdx= [HW,AX25]
 375                        BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 376                        Format: <io>,<irq>,<mode>[,<baud>]
 377                        See header of drivers/net/hamradio/baycom_ser_fdx.c.
 378
 379        baycom_ser_hdx= [HW,AX25]
 380                        BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 381                        Format: <io>,<irq>,<mode>
 382                        See header of drivers/net/hamradio/baycom_ser_hdx.c.
 383
 384        boot_delay=     Milliseconds to delay each printk during boot.
 385                        Values larger than 10 seconds (10000) are changed to
 386                        no delay (0).
 387                        Format: integer
 388
 389        bootmem_debug   [KNL] Enable bootmem allocator debug messages.
 390
 391        bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 392        bttv.radio=     Most important insmod options are available as
 393                        kernel args too.
 394        bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 395        bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 396
 397        BusLogic=       [HW,SCSI]
 398                        See drivers/scsi/BusLogic.c, comment before function
 399                        BusLogic_ParseDriverOptions().
 400
 401        c101=           [NET] Moxa C101 synchronous serial card
 402
 403        cachesize=      [BUGS=X86-32] Override level 2 CPU cache size detection.
 404                        Sometimes CPU hardware bugs make them report the cache
 405                        size incorrectly. The kernel will attempt work arounds
 406                        to fix known problems, but for some CPUs it is not
 407                        possible to determine what the correct size should be.
 408                        This option provides an override for these situations.
 409
 410        security=       [SECURITY] Choose a security module to enable at boot.
 411                        If this boot parameter is not specified, only the first
 412                        security module asking for security registration will be
 413                        loaded. An invalid security module name will be treated
 414                        as if no module has been chosen.
 415
 416        capability.disable=
 417                        [SECURITY] Disable capabilities.  This would normally
 418                        be used only if an alternative security model is to be
 419                        configured.  Potentially dangerous and should only be
 420                        used if you are entirely sure of the consequences.
 421
 422        ccw_timeout_log [S390]
 423                        See Documentation/s390/CommonIO for details.
 424
 425        cgroup_disable= [KNL] Disable a particular controller
 426                        Format: {name of the controller(s) to disable}
 427                                {Currently supported controllers - "memory"}
 428
 429        checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 430                        Format: { "0" | "1" }
 431                        See security/selinux/Kconfig help text.
 432                        0 -- check protection applied by kernel (includes
 433                                any implied execute protection).
 434                        1 -- check protection requested by application.
 435                        Default value is set via a kernel config option.
 436                        Value can be changed at runtime via
 437                                /selinux/checkreqprot.
 438
 439        cio_ignore=     [S390]
 440                        See Documentation/s390/CommonIO for details.
 441
 442        clock=          [BUGS=X86-32, HW] gettimeofday clocksource override.
 443                        [Deprecated]
 444                        Forces specified clocksource (if available) to be used
 445                        when calculating gettimeofday(). If specified
 446                        clocksource is not available, it defaults to PIT.
 447                        Format: { pit | tsc | cyclone | pmtmr }
 448
 449        clocksource=    [GENERIC_TIME] Override the default clocksource
 450                        Format: <string>
 451                        Override the default clocksource and use the clocksource
 452                        with the name specified.
 453                        Some clocksource names to choose from, depending on
 454                        the platform:
 455                        [all] jiffies (this is the base, fallback clocksource)
 456                        [ACPI] acpi_pm
 457                        [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
 458                                pxa_timer,timer3,32k_counter,timer0_1
 459                        [AVR32] avr32
 460                        [X86-32] pit,hpet,tsc,vmi-timer;
 461                                scx200_hrt on Geode; cyclone on IBM x440
 462                        [MIPS] MIPS
 463                        [PARISC] cr16
 464                        [S390] tod
 465                        [SH] SuperH
 466                        [SPARC64] tick
 467                        [X86-64] hpet,tsc
 468
 469        clearcpuid=BITNUM [X86]
 470                        Disable CPUID feature X for the kernel. See
 471                        include/asm-x86/cpufeature.h for the valid bit numbers.
 472                        Note the Linux specific bits are not necessarily
 473                        stable over kernel options, but the vendor specific
 474                        ones should be.
 475                        Also note that user programs calling CPUID directly
 476                        or using the feature without checking anything
 477                        will still see it. This just prevents it from
 478                        being used by the kernel or shown in /proc/cpuinfo.
 479                        Also note the kernel might malfunction if you disable
 480                        some critical bits.
 481
 482        code_bytes      [IA32/X86_64] How many bytes of object code to print
 483                        in an oops report.
 484                        Range: 0 - 8192
 485                        Default: 64
 486
 487        hpet=           [X86-32,HPET] option to control HPET usage
 488                        Format: { enable (default) | disable | force }
 489                        disable: disable HPET and use PIT instead
 490                        force: allow force enabled of undocumented chips (ICH4,
 491                        VIA, nVidia)
 492
 493        com20020=       [HW,NET] ARCnet - COM20020 chipset
 494                        Format:
 495                        <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 496
 497        com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 498                        Format: <io>[,<irq>]
 499
 500        com90xx=        [HW,NET]
 501                        ARCnet - COM90xx chipset (memory-mapped buffers)
 502                        Format: <io>[,<irq>[,<memstart>]]
 503
 504        condev=         [HW,S390] console device
 505        conmode=
 506
 507        console=        [KNL] Output console device and options.
 508
 509                tty<n>  Use the virtual console device <n>.
 510
 511                ttyS<n>[,options]
 512                ttyUSB0[,options]
 513                        Use the specified serial port.  The options are of
 514                        the form "bbbbpnf", where "bbbb" is the baud rate,
 515                        "p" is parity ("n", "o", or "e"), "n" is number of
 516                        bits, and "f" is flow control ("r" for RTS or
 517                        omit it).  Default is "9600n8".
 518
 519                        See Documentation/serial-console.txt for more
 520                        information.  See
 521                        Documentation/networking/netconsole.txt for an
 522                        alternative.
 523
 524                uart[8250],io,<addr>[,options]
 525                uart[8250],mmio,<addr>[,options]
 526                        Start an early, polled-mode console on the 8250/16550
 527                        UART at the specified I/O port or MMIO address,
 528                        switching to the matching ttyS device later.  The
 529                        options are the same as for ttyS, above.
 530
 531                If the device connected to the port is not a TTY but a braille
 532                device, prepend "brl," before the device type, for instance
 533                        console=brl,ttyS0
 534                For now, only VisioBraille is supported.
 535
 536        earlycon=       [KNL] Output early console device and options.
 537                uart[8250],io,<addr>[,options]
 538                uart[8250],mmio,<addr>[,options]
 539                        Start an early, polled-mode console on the 8250/16550
 540                        UART at the specified I/O port or MMIO address.
 541                        The options are the same as for ttyS, above.
 542
 543        no_console_suspend
 544                        [HW] Never suspend the console
 545                        Disable suspending of consoles during suspend and
 546                        hibernate operations.  Once disabled, debugging
 547                        messages can reach various consoles while the rest
 548                        of the system is being put to sleep (ie, while
 549                        debugging driver suspend/resume hooks).  This may
 550                        not work reliably with all consoles, but is known
 551                        to work with serial and VGA consoles.
 552
 553        cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 554                        Format:
 555                        <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 556
 557        crashkernel=nn[KMG]@ss[KMG]
 558                        [KNL] Reserve a chunk of physical memory to
 559                        hold a kernel to switch to with kexec on panic.
 560
 561        crashkernel=range1:size1[,range2:size2,...][@offset]
 562                        [KNL] Same as above, but depends on the memory
 563                        in the running system. The syntax of range is
 564                        start-[end] where start and end are both
 565                        a memory unit (amount[KMG]). See also
 566                        Documentation/kdump/kdump.txt for a example.
 567
 568        cs4232=         [HW,OSS]
 569                        Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 570
 571        cs89x0_dma=     [HW,NET]
 572                        Format: <dma>
 573
 574        cs89x0_media=   [HW,NET]
 575                        Format: { rj45 | aui | bnc }
 576
 577        dasd=           [HW,NET]
 578                        See header of drivers/s390/block/dasd_devmap.c.
 579
 580        db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 581                        (one device per port)
 582                        Format: <port#>,<type>
 583                        See also Documentation/input/joystick-parport.txt
 584
 585        debug           [KNL] Enable kernel debugging (events log level).
 586
 587        debug_locks_verbose=
 588                        [KNL] verbose self-tests
 589                        Format=<0|1>
 590                        Print debugging info while doing the locking API
 591                        self-tests.
 592                        We default to 0 (no extra messages), setting it to
 593                        1 will print _a lot_ more information - normally
 594                        only useful to kernel developers.
 595
 596        debug_objects   [KNL] Enable object debugging
 597
 598        debugpat        [X86] Enable PAT debugging
 599
 600        decnet.addr=    [HW,NET]
 601                        Format: <area>[,<node>]
 602                        See also Documentation/networking/decnet.txt.
 603
 604        vt.default_blu= [VT]
 605                        Format: <blue0>,<blue1>,<blue2>,...,<blue15>
 606                        Change the default blue palette of the console.
 607                        This is a 16-member array composed of values
 608                        ranging from 0-255.
 609
 610        vt.default_grn= [VT]
 611                        Format: <green0>,<green1>,<green2>,...,<green15>
 612                        Change the default green palette of the console.
 613                        This is a 16-member array composed of values
 614                        ranging from 0-255.
 615
 616        vt.default_red= [VT]
 617                        Format: <red0>,<red1>,<red2>,...,<red15>
 618                        Change the default red palette of the console.
 619                        This is a 16-member array composed of values
 620                        ranging from 0-255.
 621
 622        vt.default_utf8=
 623                        [VT]
 624                        Format=<0|1>
 625                        Set system-wide default UTF-8 mode for all tty's.
 626                        Default is 1, i.e. UTF-8 mode is enabled for all
 627                        newly opened terminals.
 628
 629        dhash_entries=  [KNL]
 630                        Set number of hash buckets for dentry cache.
 631
 632        digi=           [HW,SERIAL]
 633                        IO parameters + enable/disable command.
 634
 635        digiepca=       [HW,SERIAL]
 636                        See drivers/char/README.epca and
 637                        Documentation/serial/digiepca.txt.
 638
 639        disable_mtrr_cleanup [X86]
 640        enable_mtrr_cleanup [X86]
 641                        The kernel tries to adjust MTRR layout from continuous
 642                        to discrete, to make X server driver able to add WB
 643                        entry later. This parameter enables/disables that.
 644
 645        mtrr_chunk_size=nn[KMG] [X86]
 646                        used for mtrr cleanup. It is largest continous chunk
 647                        that could hold holes aka. UC entries.
 648
 649        mtrr_gran_size=nn[KMG] [X86]
 650                        Used for mtrr cleanup. It is granularity of mtrr block.
 651                        Default is 1.
 652                        Large value could prevent small alignment from
 653                        using up MTRRs.
 654
 655        mtrr_spare_reg_nr=n [X86]
 656                        Format: <integer>
 657                        Range: 0,7 : spare reg number
 658                        Default : 1
 659                        Used for mtrr cleanup. It is spare mtrr entries number.
 660                        Set to 2 or more if your graphical card needs more.
 661
 662        disable_mtrr_trim [X86, Intel and AMD only]
 663                        By default the kernel will trim any uncacheable
 664                        memory out of your available memory pool based on
 665                        MTRR settings.  This parameter disables that behavior,
 666                        possibly causing your machine to run very slowly.
 667
 668        dmasound=       [HW,OSS] Sound subsystem buffers
 669
 670        dscc4.setup=    [NET]
 671
 672        dtc3181e=       [HW,SCSI]
 673
 674        earlyprintk=    [X86-32,X86-64,SH,BLACKFIN]
 675                        earlyprintk=vga
 676                        earlyprintk=serial[,ttySn[,baudrate]]
 677                        earlyprintk=dbgp
 678
 679                        Append ",keep" to not disable it when the real console
 680                        takes over.
 681
 682                        Only vga or serial or usb debug port at a time.
 683
 684                        Currently only ttyS0 and ttyS1 are supported.
 685
 686                        Interaction with the standard serial driver is not
 687                        very good.
 688
 689                        The VGA output is eventually overwritten by the real
 690                        console.
 691
 692        eata=           [HW,SCSI]
 693
 694        edd=            [EDD]
 695                        Format: {"off" | "on" | "skip[mbr]"}
 696
 697        eisa_irq_edge=  [PARISC,HW]
 698                        See header of drivers/parisc/eisa.c.
 699
 700        elanfreq=       [X86-32]
 701                        See comment before function elanfreq_setup() in
 702                        arch/x86/kernel/cpu/cpufreq/elanfreq.c.
 703
 704        elevator=       [IOSCHED]
 705                        Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
 706                        See Documentation/block/as-iosched.txt and
 707                        Documentation/block/deadline-iosched.txt for details.
 708
 709        elfcorehdr=     [IA64,PPC,SH,X86-32,X86_64]
 710                        Specifies physical address of start of kernel core
 711                        image elf header. Generally kexec loader will
 712                        pass this option to capture kernel.
 713                        See Documentation/kdump/kdump.txt for details.
 714
 715        enforcing       [SELINUX] Set initial enforcing status.
 716                        Format: {"0" | "1"}
 717                        See security/selinux/Kconfig help text.
 718                        0 -- permissive (log only, no denials).
 719                        1 -- enforcing (deny and log).
 720                        Default value is 0.
 721                        Value can be changed at runtime via /selinux/enforce.
 722
 723        es1371=         [HW,OSS]
 724                        Format: <spdif>,[<nomix>,[<amplifier>]]
 725                        See also header of sound/oss/es1371.c.
 726
 727        ether=          [HW,NET] Ethernet cards parameters
 728                        This option is obsoleted by the "netdev=" option, which
 729                        has equivalent usage. See its documentation for details.
 730
 731        eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 732                        Format: <io>[,<irq>]
 733
 734        failslab=
 735        fail_page_alloc=
 736        fail_make_request=[KNL]
 737                        General fault injection mechanism.
 738                        Format: <interval>,<probability>,<space>,<times>
 739                        See also /Documentation/fault-injection/.
 740
 741        fd_mcs=         [HW,SCSI]
 742                        See header of drivers/scsi/fd_mcs.c.
 743
 744        fdomain=        [HW,SCSI]
 745                        See header of drivers/scsi/fdomain.c.
 746
 747        floppy=         [HW]
 748                        See Documentation/blockdev/floppy.txt.
 749
 750        force_pal_cache_flush
 751                        [IA-64] Avoid check_sal_cache_flush which may hang on
 752                        buggy SAL_CACHE_FLUSH implementations. Using this
 753                        parameter will force ia64_sal_cache_flush to call
 754                        ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
 755
 756        gamecon.map[2|3]=
 757                        [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 758                        support via parallel port (up to 5 devices per port)
 759                        Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 760                        See also Documentation/input/joystick-parport.txt
 761
 762        gamma=          [HW,DRM]
 763
 764        gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
 765                        Format: off | on
 766                        default: on
 767
 768        gdth=           [HW,SCSI]
 769                        See header of drivers/scsi/gdth.c.
 770
 771        gpt             [EFI] Forces disk with valid GPT signature but
 772                        invalid Protective MBR to be treated as GPT.
 773
 774        gvp11=          [HW,SCSI]
 775
 776        hashdist=       [KNL,NUMA] Large hashes allocated during boot
 777                        are distributed across NUMA nodes.  Defaults on
 778                        for IA-64, off otherwise.
 779                        Format: 0 | 1 (for off | on)
 780
 781        hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 782
 783        hd=             [EIDE] (E)IDE hard drive subsystem geometry
 784                        Format: <cyl>,<head>,<sect>
 785
 786        highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 787                        size of <nn>. This works even on boxes that have no
 788                        highmem otherwise. This also works to reduce highmem
 789                        size on bigger boxes.
 790
 791        highres=        [KNL] Enable/disable high resolution timer mode.
 792                        Valid parameters: "on", "off"
 793                        Default: "on"
 794
 795        hisax=          [HW,ISDN]
 796                        See Documentation/isdn/README.HiSax.
 797
 798        hugepages=      [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
 799        hugepagesz=     [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
 800                        On x86-64 and powerpc, this option can be specified
 801                        multiple times interleaved with hugepages= to reserve
 802                        huge pages of different sizes. Valid pages sizes on
 803                        x86-64 are 2M (when the CPU supports "pse") and 1G
 804                        (when the CPU supports the "pdpe1gb" cpuinfo flag)
 805                        Note that 1GB pages can only be allocated at boot time
 806                        using hugepages= and not freed afterwards.
 807        default_hugepagesz=
 808                        [same as hugepagesz=] The size of the default
 809                        HugeTLB page size. This is the size represented by
 810                        the legacy /proc/ hugepages APIs, used for SHM, and
 811                        default size when mounting hugetlbfs filesystems.
 812                        Defaults to the default architecture's huge page size
 813                        if not specified.
 814
 815        hlt             [BUGS=ARM,SH]
 816
 817        i8042.debug     [HW] Toggle i8042 debug mode
 818        i8042.direct    [HW] Put keyboard port into non-translated mode
 819        i8042.dumbkbd   [HW] Pretend that controller can only read data from
 820                             keyboard and cannot control its state
 821                             (Don't attempt to blink the leds)
 822        i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 823        i8042.nokbd     [HW] Don't check/create keyboard port
 824        i8042.noloop    [HW] Disable the AUX Loopback command while probing
 825                             for the AUX port
 826        i8042.nomux     [HW] Don't check presence of an active multiplexing
 827                             controller
 828        i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 829                             controllers
 830        i8042.panicblink=
 831                        [HW] Frequency with which keyboard LEDs should blink
 832                             when kernel panics (default is 0.5 sec)
 833        i8042.reset     [HW] Reset the controller during init and cleanup
 834        i8042.unlock    [HW] Unlock (ignore) the keylock
 835
 836        i810=           [HW,DRM]
 837
 838        i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 839                        indicates that the driver is running on unsupported
 840                        hardware.
 841        i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 842                        does not match list of supported models.
 843        i8k.power_status
 844                        [HW] Report power status in /proc/i8k
 845                        (disabled by default)
 846        i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 847                        capability is set.
 848
 849        ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 850                        See Documentation/mca.txt.
 851
 852        icn=            [HW,ISDN]
 853                        Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 854
 855        ide=            [HW] (E)IDE subsystem
 856                        Format: ide=nodma or ide=doubler
 857                        See Documentation/ide/ide.txt.
 858
 859        idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 860                        See Documentation/ide/ide.txt.
 861
 862        idle=           [X86]
 863                        Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
 864                        Poll forces a polling idle loop that can slightly improves the performance
 865                        of waking up a idle CPU, but will use a lot of power and make the system
 866                        run hot. Not recommended.
 867                        idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
 868                        to not use it because it doesn't save as much power as a normal idle
 869                        loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
 870                        as idle=poll.
 871                        idle=halt. Halt is forced to be used for CPU idle.
 872                        In such case C2/C3 won't be used again.
 873                        idle=nomwait. Disable mwait for CPU C-states
 874
 875        ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
 876                        Claim all unknown PCI IDE storage controllers.
 877
 878        ignore_loglevel [KNL]
 879                        Ignore loglevel setting - this will print /all/
 880                        kernel messages to the console. Useful for debugging.
 881
 882        ihash_entries=  [KNL]
 883                        Set number of hash buckets for inode cache.
 884
 885        in2000=         [HW,SCSI]
 886                        See header of drivers/scsi/in2000.c.
 887
 888        init=           [KNL]
 889                        Format: <full_path>
 890                        Run specified binary instead of /sbin/init as init
 891                        process.
 892
 893        initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 894                        for working out where the kernel is dying during
 895                        startup.
 896
 897        initrd=         [BOOT] Specify the location of the initial ramdisk
 898
 899        inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 900                        Format: <irq>
 901
 902        inttest=        [IA64]
 903
 904        iommu=          [x86]
 905                off
 906                force
 907                noforce
 908                biomerge
 909                panic
 910                nopanic
 911                merge
 912                nomerge
 913                forcesac
 914                soft
 915
 916
 917        intel_iommu=    [DMAR] Intel IOMMU driver (DMAR) option
 918                off
 919                        Disable intel iommu driver.
 920                igfx_off [Default Off]
 921                        By default, gfx is mapped as normal device. If a gfx
 922                        device has a dedicated DMAR unit, the DMAR unit is
 923                        bypassed by not enabling DMAR with this option. In
 924                        this case, gfx device will use physical address for
 925                        DMA.
 926                forcedac [x86_64]
 927                        With this option iommu will not optimize to look
 928                        for io virtual address below 32 bit forcing dual
 929                        address cycle on pci bus for cards supporting greater
 930                        than 32 bit addressing. The default is to look
 931                        for translation below 32 bit and if not available
 932                        then look in the higher range.
 933                strict [Default Off]
 934                        With this option on every unmap_single operation will
 935                        result in a hardware IOTLB flush operation as opposed
 936                        to batching them for performance.
 937
 938        io_delay=       [X86-32,X86-64] I/O delay method
 939                0x80
 940                        Standard port 0x80 based delay
 941                0xed
 942                        Alternate port 0xed based delay (needed on some systems)
 943                udelay
 944                        Simple two microseconds delay
 945                none
 946                        No delay
 947
 948        io7=            [HW] IO7 for Marvel based alpha systems
 949                        See comment before marvel_specify_io7 in
 950                        arch/alpha/kernel/core_marvel.c.
 951
 952        ip=             [IP_PNP]
 953                        See Documentation/filesystems/nfsroot.txt.
 954
 955        ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 956                        See comment before ip2_setup() in
 957                        drivers/char/ip2/ip2base.c.
 958
 959        ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 960                        See header of drivers/scsi/ips.c.
 961
 962        ports=          [IP_VS_FTP] IPVS ftp helper module
 963                        Default is 21.
 964                        Up to 8 (IP_VS_APP_MAX_PORTS) ports
 965                        may be specified.
 966                        Format: <port>,<port>....
 967
 968        irqfixup        [HW]
 969                        When an interrupt is not handled search all handlers
 970                        for it. Intended to get systems with badly broken
 971                        firmware running.
 972
 973        irqpoll         [HW]
 974                        When an interrupt is not handled search all handlers
 975                        for it. Also check all handlers each timer
 976                        interrupt. Intended to get systems with badly broken
 977                        firmware running.
 978
 979        isapnp=         [ISAPNP]
 980                        Format: <RDP>,<reset>,<pci_scan>,<verbosity>
 981
 982        isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 983                        Format:
 984                        <cpu number>,...,<cpu number>
 985                        or
 986                        <cpu number>-<cpu number>
 987                        (must be a positive range in ascending order)
 988                        or a mixture
 989                        <cpu number>,...,<cpu number>-<cpu number>
 990
 991                        This option can be used to specify one or more CPUs
 992                        to isolate from the general SMP balancing and scheduling
 993                        algorithms. You can move a process onto or off an
 994                        "isolated" CPU via the CPU affinity syscalls or cpuset.
 995                        <cpu number> begins at 0 and the maximum value is
 996                        "number of CPUs in system - 1".
 997
 998                        This option is the preferred way to isolate CPUs. The
 999                        alternative -- manually setting the CPU mask of all
1000                        tasks in the system -- can cause problems and
1001                        suboptimal load balancer performance.
1002
1003        iucv=           [HW,NET]
1004
1005        js=             [HW,JOY] Analog joystick
1006                        See Documentation/input/joystick.txt.
1007
1008        kernelcore=nn[KMG]      [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1009                        specifies the amount of memory usable by the kernel
1010                        for non-movable allocations.  The requested amount is
1011                        spread evenly throughout all nodes in the system. The
1012                        remaining memory in each node is used for Movable
1013                        pages. In the event, a node is too small to have both
1014                        kernelcore and Movable pages, kernelcore pages will
1015                        take priority and other nodes will have a larger number
1016                        of kernelcore pages.  The Movable zone is used for the
1017                        allocation of pages that may be reclaimed or moved
1018                        by the page migration subsystem.  This means that
1019                        HugeTLB pages may not be allocated from this zone.
1020                        Note that allocations like PTEs-from-HighMem still
1021                        use the HighMem zone if it exists, and the Normal
1022                        zone if it does not.
1023
1024        movablecore=nn[KMG]     [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1025                        is similar to kernelcore except it specifies the
1026                        amount of memory used for migratable allocations.
1027                        If both kernelcore and movablecore is specified,
1028                        then kernelcore will be at *least* the specified
1029                        value but may be more. If movablecore on its own
1030                        is specified, the administrator must be careful
1031                        that the amount of memory usable for all allocations
1032                        is not too small.
1033
1034        keepinitrd      [HW,ARM]
1035
1036        kstack=N        [X86-32,X86-64] Print N words from the kernel stack
1037                        in oops dumps.
1038
1039        kgdboc=         [HW] kgdb over consoles.
1040                        Requires a tty driver that supports console polling.
1041                        (only serial suported for now)
1042                        Format: <serial_device>[,baud]
1043
1044        kmac=           [MIPS] korina ethernet MAC address.
1045                        Configure the RouterBoard 532 series on-chip
1046                        Ethernet adapter MAC address.
1047
1048        l2cr=           [PPC]
1049
1050        l3cr=           [PPC]
1051
1052        lapic           [X86-32,APIC] Enable the local APIC even if BIOS
1053                        disabled it.
1054
1055        lapic_timer_c2_ok       [X86-32,x86-64,APIC] trust the local apic timer in
1056                        C2 power state.
1057
1058        libata.dma=     [LIBATA] DMA control
1059                        libata.dma=0      Disable all PATA and SATA DMA
1060                        libata.dma=1      PATA and SATA Disk DMA only
1061                        libata.dma=2      ATAPI (CDROM) DMA only
1062                        libata.dma=4      Compact Flash DMA only 
1063                        Combinations also work, so libata.dma=3 enables DMA
1064                        for disks and CDROMs, but not CFs.
1065
1066        libata.noacpi   [LIBATA] Disables use of ACPI in libata suspend/resume
1067                        when set.
1068                        Format: <int>
1069
1070        libata.force=   [LIBATA] Force configurations.  The format is comma
1071                        separated list of "[ID:]VAL" where ID is
1072                        PORT[:DEVICE].  PORT and DEVICE are decimal numbers
1073                        matching port, link or device.  Basically, it matches
1074                        the ATA ID string printed on console by libata.  If
1075                        the whole ID part is omitted, the last PORT and DEVICE
1076                        values are used.  If ID hasn't been specified yet, the
1077                        configuration applies to all ports, links and devices.
1078
1079                        If only DEVICE is omitted, the parameter applies to
1080                        the port and all links and devices behind it.  DEVICE
1081                        number of 0 either selects the first device or the
1082                        first fan-out link behind PMP device.  It does not
1083                        select the host link.  DEVICE number of 15 selects the
1084                        host link and device attached to it.
1085
1086                        The VAL specifies the configuration to force.  As long
1087                        as there's no ambiguity shortcut notation is allowed.
1088                        For example, both 1.5 and 1.5G would work for 1.5Gbps.
1089                        The following configurations can be forced.
1090
1091                        * Cable type: 40c, 80c, short40c, unk, ign or sata.
1092                          Any ID with matching PORT is used.
1093
1094                        * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1095
1096                        * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1097                          udma[/][16,25,33,44,66,100,133] notation is also
1098                          allowed.
1099
1100                        * [no]ncq: Turn on or off NCQ.
1101
1102                        * nohrst, nosrst, norst: suppress hard, soft
1103                          and both resets.
1104
1105                        If there are multiple matching configurations changing
1106                        the same attribute, the last one is used.
1107
1108        load_ramdisk=   [RAM] List of ramdisks to load from floppy
1109                        See Documentation/blockdev/ramdisk.txt.
1110
1111        lockd.nlm_grace_period=P  [NFS] Assign grace period.
1112                        Format: <integer>
1113
1114        lockd.nlm_tcpport=N     [NFS] Assign TCP port.
1115                        Format: <integer>
1116
1117        lockd.nlm_timeout=T     [NFS] Assign timeout value.
1118                        Format: <integer>
1119
1120        lockd.nlm_udpport=M     [NFS] Assign UDP port.
1121                        Format: <integer>
1122
1123        logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
1124                        Format: <irq>
1125
1126        loglevel=       All Kernel Messages with a loglevel smaller than the
1127                        console loglevel will be printed to the console. It can
1128                        also be changed with klogd or other programs. The
1129                        loglevels are defined as follows:
1130
1131                        0 (KERN_EMERG)          system is unusable
1132                        1 (KERN_ALERT)          action must be taken immediately
1133                        2 (KERN_CRIT)           critical conditions
1134                        3 (KERN_ERR)            error conditions
1135                        4 (KERN_WARNING)        warning conditions
1136                        5 (KERN_NOTICE)         normal but significant condition
1137                        6 (KERN_INFO)           informational
1138                        7 (KERN_DEBUG)          debug-level messages
1139
1140        log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
1141                        Format: { n | nk | nM }
1142                        n must be a power of two.  The default size
1143                        is set in the kernel config file.
1144
1145        logo.nologo     [FB] Disables display of the built-in Linux logo.
1146                        This may be used to provide more screen space for
1147                        kernel log messages and is useful when debugging
1148                        kernel boot problems.
1149
1150        lp=0            [LP]    Specify parallel ports to use, e.g,
1151        lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
1152        lp=reset                first parallel port). 'lp=0' disables the
1153        lp=auto                 printer driver. 'lp=reset' (which can be
1154                                specified in addition to the ports) causes
1155                                attached printers to be reset. Using
1156                                lp=port1,port2,... specifies the parallel ports
1157                                to associate lp devices with, starting with
1158                                lp0. A port specification may be 'none' to skip
1159                                that lp device, or a parport name such as
1160                                'parport0'. Specifying 'lp=auto' instead of a
1161                                port specification list means that device IDs
1162                                from each port should be examined, to see if
1163                                an IEEE 1284-compliant printer is attached; if
1164                                so, the driver will manage that printer.
1165                                See also header of drivers/char/lp.c.
1166
1167        lpj=n           [KNL]
1168                        Sets loops_per_jiffy to given constant, thus avoiding
1169                        time-consuming boot-time autodetection (up to 250 ms per
1170                        CPU). 0 enables autodetection (default). To determine
1171                        the correct value for your kernel, boot with normal
1172                        autodetection and see what value is printed. Note that
1173                        on SMP systems the preset will be applied to all CPUs,
1174                        which is likely to cause problems if your CPUs need
1175                        significantly divergent settings. An incorrect value
1176                        will cause delays in the kernel to be wrong, leading to
1177                        unpredictable I/O errors and other breakage. Although
1178                        unlikely, in the extreme case this might damage your
1179                        hardware.
1180
1181        ltpc=           [NET]
1182                        Format: <io>,<irq>,<dma>
1183
1184        mac5380=        [HW,SCSI] Format:
1185                        <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1186
1187        machvec=        [IA64] Force the use of a particular machine-vector
1188                        (machvec) in a generic kernel.
1189                        Example: machvec=hpzx1_swiotlb
1190
1191        max_loop=       [LOOP] Maximum number of loopback devices that can
1192                        be mounted
1193                        Format: <1-256>
1194
1195        maxcpus=        [SMP] Maximum number of processors that an SMP kernel
1196                        should make use of.  maxcpus=n : n >= 0 limits the
1197                        kernel to using 'n' processors.  n=0 is a special case,
1198                        it is equivalent to "nosmp", which also disables
1199                        the IO APIC.
1200
1201        max_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory greater than
1202                        or equal to this physical address is ignored.
1203
1204        max_luns=       [SCSI] Maximum number of LUNs to probe.
1205                        Should be between 1 and 2^32-1.
1206
1207        max_report_luns=
1208                        [SCSI] Maximum number of LUNs received.
1209                        Should be between 1 and 16384.
1210
1211        mcatest=        [IA-64]
1212
1213        mce             [X86-32] Machine Check Exception
1214
1215        mce=option      [X86-64] See Documentation/x86/x86_64/boot-options.txt
1216
1217        md=             [HW] RAID subsystems devices and level
1218                        See Documentation/md.txt.
1219
1220        mdacon=         [MDA]
1221                        Format: <first>,<last>
1222                        Specifies range of consoles to be captured by the MDA.
1223
1224        mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
1225                        Amount of memory to be used when the kernel is not able
1226                        to see the whole system memory or for test.
1227                        [X86-32] Use together with memmap= to avoid physical
1228                        address space collisions. Without memmap= PCI devices
1229                        could be placed at addresses belonging to unused RAM.
1230
1231        mem=nopentium   [BUGS=X86-32] Disable usage of 4MB pages for kernel
1232                        memory.
1233
1234        memchunk=nn[KMG]
1235                        [KNL,SH] Allow user to override the default size for
1236                        per-device physically contiguous DMA buffers.
1237
1238        memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1239                        E820 memory map, as specified by the user.
1240                        Such memmap=exactmap lines can be constructed based on
1241                        BIOS output or other requirements. See the memmap=nn@ss
1242                        option description.
1243
1244        memmap=nn[KMG]@ss[KMG]
1245                        [KNL] Force usage of a specific region of memory
1246                        Region of memory to be used, from ss to ss+nn.
1247
1248        memmap=nn[KMG]#ss[KMG]
1249                        [KNL,ACPI] Mark specific memory as ACPI data.
1250                        Region of memory to be used, from ss to ss+nn.
1251
1252        memmap=nn[KMG]$ss[KMG]
1253                        [KNL,ACPI] Mark specific memory as reserved.
1254                        Region of memory to be used, from ss to ss+nn.
1255                        Example: Exclude memory from 0x18690000-0x1869ffff
1256                                 memmap=64K$0x18690000
1257                                 or
1258                                 memmap=0x10000$0x18690000
1259
1260        memory_corruption_check=0/1 [X86]
1261                        Some BIOSes seem to corrupt the first 64k of
1262                        memory when doing things like suspend/resume.
1263                        Setting this option will scan the memory
1264                        looking for corruption.  Enabling this will
1265                        both detect corruption and prevent the kernel
1266                        from using the memory being corrupted.
1267                        However, its intended as a diagnostic tool; if
1268                        repeatable BIOS-originated corruption always
1269                        affects the same memory, you can use memmap=
1270                        to prevent the kernel from using that memory.
1271
1272        memory_corruption_check_size=size [X86]
1273                        By default it checks for corruption in the low
1274                        64k, making this memory unavailable for normal
1275                        use.  Use this parameter to scan for
1276                        corruption in more or less memory.
1277
1278        memory_corruption_check_period=seconds [X86]
1279                        By default it checks for corruption every 60
1280                        seconds.  Use this parameter to check at some
1281                        other rate.  0 disables periodic checking.
1282
1283        memtest=        [KNL,X86] Enable memtest
1284                        Format: <integer>
1285                        range: 0,4 : pattern number
1286                        default : 0 <disable>
1287
1288        meye.*=         [HW] Set MotionEye Camera parameters
1289                        See Documentation/video4linux/meye.txt.
1290
1291        mfgpt_irq=      [IA-32] Specify the IRQ to use for the
1292                        Multi-Function General Purpose Timers on AMD Geode
1293                        platforms.
1294
1295        mfgptfix        [X86-32] Fix MFGPT timers on AMD Geode platforms when
1296                        the BIOS has incorrectly applied a workaround. TinyBIOS
1297                        version 0.98 is known to be affected, 0.99 fixes the
1298                        problem by letting the user disable the workaround.
1299
1300        mga=            [HW,DRM]
1301
1302        min_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory below this
1303                        physical address is ignored.
1304
1305        mminit_loglevel=
1306                        [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1307                        parameter allows control of the logging verbosity for
1308                        the additional memory initialisation checks. A value
1309                        of 0 disables mminit logging and a level of 4 will
1310                        log everything. Information is printed at KERN_DEBUG
1311                        so loglevel=8 may also need to be specified.
1312
1313        mousedev.tap_time=
1314                        [MOUSE] Maximum time between finger touching and
1315                        leaving touchpad surface for touch to be considered
1316                        a tap and be reported as a left button click (for
1317                        touchpads working in absolute mode only).
1318                        Format: <msecs>
1319        mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
1320                        reporting absolute coordinates, such as tablets
1321        mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
1322                        reporting absolute coordinates, such as tablets
1323
1324        mpu401=         [HW,OSS]
1325                        Format: <io>,<irq>
1326
1327        MTD_Partition=  [MTD]
1328                        Format: <name>,<region-number>,<size>,<offset>
1329
1330        MTD_Region=     [MTD] Format:
1331                        <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1332
1333        mtdparts=       [MTD]
1334                        See drivers/mtd/cmdlinepart.c.
1335
1336        mtdset=         [ARM]
1337                        ARM/S3C2412 JIVE boot control
1338
1339                        See arch/arm/mach-s3c2412/mach-jive.c
1340
1341        mtouchusb.raw_coordinates=
1342                        [HW] Make the MicroTouch USB driver use raw coordinates
1343                        ('y', default) or cooked coordinates ('n')
1344
1345        n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
1346
1347        NCR_D700=       [HW,SCSI]
1348                        See header of drivers/scsi/NCR_D700.c.
1349
1350        ncr5380=        [HW,SCSI]
1351
1352        ncr53c400=      [HW,SCSI]
1353
1354        ncr53c400a=     [HW,SCSI]
1355
1356        ncr53c406a=     [HW,SCSI]
1357
1358        ncr53c8xx=      [HW,SCSI]
1359
1360        netdev=         [NET] Network devices parameters
1361                        Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1362                        Note that mem_start is often overloaded to mean
1363                        something different and driver-specific.
1364                        This usage is only documented in each driver source
1365                        file if at all.
1366
1367        nf_conntrack.acct=
1368                        [NETFILTER] Enable connection tracking flow accounting
1369                        0 to disable accounting
1370                        1 to enable accounting
1371                        Default value depends on CONFIG_NF_CT_ACCT that is
1372                        going to be removed in 2.6.29.
1373
1374        nfsaddrs=       [NFS]
1375                        See Documentation/filesystems/nfsroot.txt.
1376
1377        nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
1378                        See Documentation/filesystems/nfsroot.txt.
1379
1380        nfs.callback_tcpport=
1381                        [NFS] set the TCP port on which the NFSv4 callback
1382                        channel should listen.
1383
1384        nfs.idmap_cache_timeout=
1385                        [NFS] set the maximum lifetime for idmapper cache
1386                        entries.
1387
1388        nfs.enable_ino64=
1389                        [NFS] enable 64-bit inode numbers.
1390                        If zero, the NFS client will fake up a 32-bit inode
1391                        number for the readdir() and stat() syscalls instead
1392                        of returning the full 64-bit number.
1393                        The default is to return 64-bit inode numbers.
1394
1395        nmi_debug=      [KNL,AVR32] Specify one or more actions to take
1396                        when a NMI is triggered.
1397                        Format: [state][,regs][,debounce][,die]
1398
1399        nmi_watchdog=   [KNL,BUGS=X86-32] Debugging features for SMP kernels
1400
1401        no387           [BUGS=X86-32] Tells the kernel to use the 387 maths
1402                        emulation library even if a 387 maths coprocessor
1403                        is present.
1404
1405        noaliencache    [MM, NUMA, SLAB] Disables the allocation of alien
1406                        caches in the slab allocator.  Saves per-node memory,
1407                        but will impact performance.
1408
1409        noalign         [KNL,ARM]
1410
1411        noapic          [SMP,APIC] Tells the kernel to not make use of any
1412                        IOAPICs that may be present in the system.
1413
1414        nobats          [PPC] Do not use BATs for mapping kernel lowmem
1415                        on "Classic" PPC cores.
1416
1417        nocache         [ARM]
1418
1419        nodelayacct     [KNL] Disable per-task delay accounting
1420
1421        nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
1422
1423        nodsp           [SH] Disable hardware DSP at boot time.
1424
1425        noefi           [X86-32,X86-64] Disable EFI runtime services support.
1426
1427        noexec          [IA-64]
1428
1429        noexec          [X86-32,X86-64]
1430                        On X86-32 available only on PAE configured kernels.
1431                        noexec=on: enable non-executable mappings (default)
1432                        noexec=off: disable non-executable mappings
1433
1434        noexec32        [X86-64]
1435                        This affects only 32-bit executables.
1436                        noexec32=on: enable non-executable mappings (default)
1437                                read doesn't imply executable mappings
1438                        noexec32=off: disable non-executable mappings
1439                                read implies executable mappings
1440
1441        nofpu           [SH] Disable hardware FPU at boot time.
1442
1443        nofxsr          [BUGS=X86-32] Disables x86 floating point extended
1444                        register save and restore. The kernel will only save
1445                        legacy floating-point registers on task switch.
1446
1447        noclflush       [BUGS=X86] Don't use the CLFLUSH instruction
1448
1449        nohlt           [BUGS=ARM,SH]
1450
1451        no-hlt          [BUGS=X86-32] Tells the kernel that the hlt
1452                        instruction doesn't work correctly and not to
1453                        use it.
1454
1455        nohalt          [IA-64] Tells the kernel not to use the power saving
1456                        function PAL_HALT_LIGHT when idle. This increases
1457                        power-consumption. On the positive side, it reduces
1458                        interrupt wake-up latency, which may improve performance
1459                        in certain environments such as networked servers or
1460                        real-time systems.
1461
1462        nohz=           [KNL] Boottime enable/disable dynamic ticks
1463                        Valid arguments: on, off
1464                        Default: on
1465
1466        noirqdebug      [X86-32] Disables the code which attempts to detect and
1467                        disable unhandled interrupt sources.
1468
1469        no_timer_check  [X86-32,X86_64,APIC] Disables the code which tests for
1470                        broken timer IRQ sources.
1471
1472        noisapnp        [ISAPNP] Disables ISA PnP code.
1473
1474        noinitrd        [RAM] Tells the kernel not to load any configured
1475                        initial RAM disk.
1476
1477        nointroute      [IA-64]
1478
1479        nojitter        [IA64] Disables jitter checking for ITC timers.
1480
1481        nolapic         [X86-32,APIC] Do not enable or use the local APIC.
1482
1483        nolapic_timer   [X86-32,APIC] Do not use the local APIC timer.
1484
1485        nox2apic        [X86-64,APIC] Do not enable x2APIC mode.
1486
1487        x2apic_phys     [X86-64,APIC] Use x2apic physical mode instead of
1488                        default x2apic cluster mode on platforms
1489                        supporting x2apic.
1490
1491        noltlbs         [PPC] Do not use large page/tlb entries for kernel
1492                        lowmem mapping on PPC40x.
1493
1494        nomca           [IA-64] Disable machine check abort handling
1495
1496        nomce           [X86-32] Machine Check Exception
1497
1498        nomfgpt         [X86-32] Disable Multi-Function General Purpose
1499                        Timer usage (for AMD Geode machines).
1500
1501        noreplace-paravirt      [X86-32,PV_OPS] Don't patch paravirt_ops
1502
1503        noreplace-smp   [X86-32,SMP] Don't replace SMP instructions
1504                        with UP alternatives
1505
1506        noresidual      [PPC] Don't use residual data on PReP machines.
1507
1508        noresume        [SWSUSP] Disables resume and restores original swap
1509                        space.
1510
1511        no-scroll       [VGA] Disables scrollback.
1512                        This is required for the Braillex ib80-piezo Braille
1513                        reader made by F.H. Papenmeier (Germany).
1514
1515        nosbagart       [IA-64]
1516
1517        nosep           [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1518
1519        nosmp           [SMP] Tells an SMP kernel to act as a UP kernel,
1520                        and disable the IO APIC.  legacy for "maxcpus=0".
1521
1522        nosoftlockup    [KNL] Disable the soft-lockup detector.
1523
1524        nosync          [HW,M68K] Disables sync negotiation for all devices.
1525
1526        notsc           [BUGS=X86-32] Disable Time Stamp Counter
1527
1528        nousb           [USB] Disable the USB subsystem
1529
1530        nowb            [ARM]
1531
1532        nptcg=          [IA64] Override max number of concurrent global TLB
1533                        purges which is reported from either PAL_VM_SUMMARY or
1534                        SAL PALO.
1535
1536        numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1537                        one of ['zone', 'node', 'default'] can be specified
1538                        This can be set from sysctl after boot.
1539                        See Documentation/sysctl/vm.txt for details.
1540
1541        nr_uarts=       [SERIAL] maximum number of UARTs to be registered.
1542
1543        olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1544                        Rather than timing out after 20 ms if an EC
1545                        command is not properly ACKed, override the length
1546                        of the timeout.  We have interrupts disabled while
1547                        waiting for the ACK, so if this is set too high
1548                        interrupts *may* be lost!
1549
1550        opl3=           [HW,OSS]
1551                        Format: <io>
1552
1553        oprofile.timer= [HW]
1554                        Use timer interrupt instead of performance counters
1555
1556        osst=           [HW,SCSI] SCSI Tape Driver
1557                        Format: <buffer_size>,<write_threshold>
1558                        See also Documentation/scsi/st.txt.
1559
1560        panic=          [KNL] Kernel behaviour on panic
1561                        Format: <timeout>
1562
1563        parkbd.port=    [HW] Parallel port number the keyboard adapter is
1564                        connected to, default is 0.
1565                        Format: <parport#>
1566        parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
1567                        0 for XT, 1 for AT (default is AT).
1568                        Format: <mode>
1569
1570        parport=        [HW,PPT] Specify parallel ports. 0 disables.
1571                        Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1572                        Use 'auto' to force the driver to use any
1573                        IRQ/DMA settings detected (the default is to
1574                        ignore detected IRQ/DMA settings because of
1575                        possible conflicts). You can specify the base
1576                        address, IRQ, and DMA settings; IRQ and DMA
1577                        should be numbers, or 'auto' (for using detected
1578                        settings on that particular port), or 'nofifo'
1579                        (to avoid using a FIFO even if it is detected).
1580                        Parallel ports are assigned in the order they
1581                        are specified on the command line, starting
1582                        with parport0.
1583
1584        parport_init_mode=      [HW,PPT]
1585                        Configure VIA parallel port to operate in
1586                        a specific mode. This is necessary on Pegasos
1587                        computer where firmware has no options for setting
1588                        up parallel port mode and sets it to spp.
1589                        Currently this function knows 686a and 8231 chips.
1590                        Format: [spp|ps2|epp|ecp|ecpepp]
1591
1592        pas2=           [HW,OSS] Format:
1593                        <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1594
1595        pas16=          [HW,SCSI]
1596                        See header of drivers/scsi/pas16.c.
1597
1598        pause_on_oops=
1599                        Halt all CPUs after the first oops has been printed for
1600                        the specified number of seconds.  This is to be used if
1601                        your oopses keep scrolling off the screen.
1602
1603        pcbit=          [HW,ISDN]
1604
1605        pcd.            [PARIDE]
1606                        See header of drivers/block/paride/pcd.c.
1607                        See also Documentation/blockdev/paride.txt.
1608
1609        pci=option[,option...]  [PCI] various PCI subsystem options:
1610                off             [X86] don't probe for the PCI bus
1611                bios            [X86-32] force use of PCI BIOS, don't access
1612                                the hardware directly. Use this if your machine
1613                                has a non-standard PCI host bridge.
1614                nobios          [X86-32] disallow use of PCI BIOS, only direct
1615                                hardware access methods are allowed. Use this
1616                                if you experience crashes upon bootup and you
1617                                suspect they are caused by the BIOS.
1618                conf1           [X86] Force use of PCI Configuration
1619                                Mechanism 1.
1620                conf2           [X86] Force use of PCI Configuration
1621                                Mechanism 2.
1622                noaer           [PCIE] If the PCIEAER kernel config parameter is
1623                                enabled, this kernel boot option can be used to
1624                                disable the use of PCIE advanced error reporting.
1625                nodomains       [PCI] Disable support for multiple PCI
1626                                root domains (aka PCI segments, in ACPI-speak).
1627                nommconf        [X86-32,X86_64] Disable use of MMCONFIG for PCI
1628                                Configuration
1629                nomsi           [MSI] If the PCI_MSI kernel config parameter is
1630                                enabled, this kernel boot option can be used to
1631                                disable the use of MSI interrupts system-wide.
1632                biosirq         [X86-32] Use PCI BIOS calls to get the interrupt
1633                                routing table. These calls are known to be buggy
1634                                on several machines and they hang the machine
1635                                when used, but on other computers it's the only
1636                                way to get the interrupt routing table. Try
1637                                this option if the kernel is unable to allocate
1638                                IRQs or discover secondary PCI buses on your
1639                                motherboard.
1640                rom             [X86] Assign address space to expansion ROMs.
1641                                Use with caution as certain devices share
1642                                address decoders between ROMs and other
1643                                resources.
1644                norom           [X86] Do not assign address space to
1645                                expansion ROMs that do not already have
1646                                BIOS assigned address ranges.
1647                irqmask=0xMMMM  [X86] Set a bit mask of IRQs allowed to be
1648                                assigned automatically to PCI devices. You can
1649                                make the kernel exclude IRQs of your ISA cards
1650                                this way.
1651                pirqaddr=0xAAAAA        [X86] Specify the physical address
1652                                of the PIRQ table (normally generated
1653                                by the BIOS) if it is outside the
1654                                F0000h-100000h range.
1655                lastbus=N       [X86] Scan all buses thru bus #N. Can be
1656                                useful if the kernel is unable to find your
1657                                secondary buses and you want to tell it
1658                                explicitly which ones they are.
1659                assign-busses   [X86] Always assign all PCI bus
1660                                numbers ourselves, overriding
1661                                whatever the firmware may have done.
1662                usepirqmask     [X86] Honor the possible IRQ mask stored
1663                                in the BIOS $PIR table. This is needed on
1664                                some systems with broken BIOSes, notably
1665                                some HP Pavilion N5400 and Omnibook XE3
1666                                notebooks. This will have no effect if ACPI
1667                                IRQ routing is enabled.
1668                noacpi          [X86] Do not use ACPI for IRQ routing
1669                                or for PCI scanning.
1670                use_crs         [X86] Use _CRS for PCI resource
1671                                allocation.
1672                routeirq        Do IRQ routing for all PCI devices.
1673                                This is normally done in pci_enable_device(),
1674                                so this option is a temporary workaround
1675                                for broken drivers that don't call it.
1676                skip_isa_align  [X86] do not align io start addr, so can
1677                                handle more pci cards
1678                firmware        [ARM] Do not re-enumerate the bus but instead
1679                                just use the configuration from the
1680                                bootloader. This is currently used on
1681                                IXP2000 systems where the bus has to be
1682                                configured a certain way for adjunct CPUs.
1683                noearly         [X86] Don't do any early type 1 scanning.
1684                                This might help on some broken boards which
1685                                machine check when some devices' config space
1686                                is read. But various workarounds are disabled
1687                                and some IOMMU drivers will not work.
1688                bfsort          Sort PCI devices into breadth-first order.
1689                                This sorting is done to get a device
1690                                order compatible with older (<= 2.4) kernels.
1691                nobfsort        Don't sort PCI devices into breadth-first order.
1692                cbiosize=nn[KMG]        The fixed amount of bus space which is
1693                                reserved for the CardBus bridge's IO window.
1694                                The default value is 256 bytes.
1695                cbmemsize=nn[KMG]       The fixed amount of bus space which is
1696                                reserved for the CardBus bridge's memory
1697                                window. The default value is 64 megabytes.
1698
1699        pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State Power
1700                        Management.
1701                off     Disable ASPM.
1702                force   Enable ASPM even on devices that claim not to support it.
1703                        WARNING: Forcing ASPM on may cause system lockups.
1704
1705        pcmv=           [HW,PCMCIA] BadgePAD 4
1706
1707        pd.             [PARIDE]
1708                        See Documentation/blockdev/paride.txt.
1709
1710        pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1711                        boot time.
1712                        Format: { 0 | 1 }
1713                        See arch/parisc/kernel/pdc_chassis.c
1714
1715        pf.             [PARIDE]
1716                        See Documentation/blockdev/paride.txt.
1717
1718        pg.             [PARIDE]
1719                        See Documentation/blockdev/paride.txt.
1720
1721        pirq=           [SMP,APIC] Manual mp-table setup
1722                        See Documentation/x86/i386/IO-APIC.txt.
1723
1724        plip=           [PPT,NET] Parallel port network link
1725                        Format: { parport<nr> | timid | 0 }
1726                        See also Documentation/parport.txt.
1727
1728        pmtmr=          [X86] Manual setup of pmtmr I/O Port. 
1729                        Override pmtimer IOPort with a hex value.
1730                        e.g. pmtmr=0x508
1731
1732        pnp.debug       [PNP]
1733                        Enable PNP debug messages.  This depends on the
1734                        CONFIG_PNP_DEBUG_MESSAGES option.
1735
1736        pnpacpi=        [ACPI]
1737                        { off }
1738
1739        pnpbios=        [ISAPNP]
1740                        { on | off | curr | res | no-curr | no-res }
1741
1742        pnp_reserve_irq=
1743                        [ISAPNP] Exclude IRQs for the autoconfiguration
1744
1745        pnp_reserve_dma=
1746                        [ISAPNP] Exclude DMAs for the autoconfiguration
1747
1748        pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1749                        Ranges are in pairs (I/O port base and size).
1750
1751        pnp_reserve_mem=
1752                        [ISAPNP] Exclude memory regions for the
1753                        autoconfiguration.
1754                        Ranges are in pairs (memory base and size).
1755
1756        dynamic_printk
1757                        Enables pr_debug()/dev_dbg() calls if
1758                        CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1759                        be switched on/off via <debugfs>/dynamic_printk/modules
1760
1761        print-fatal-signals=
1762                        [KNL] debug: print fatal signals
1763                        print-fatal-signals=1: print segfault info to
1764                        the kernel console.
1765                        default: off.
1766
1767        printk.time=    Show timing data prefixed to each printk message line
1768                        Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
1769
1770        profile=        [KNL] Enable kernel profiling via /proc/profile
1771                        Format: [schedule,]<number>
1772                        Param: "schedule" - profile schedule points.
1773                        Param: <number> - step/bucket size as a power of 2 for
1774                                statistical time based profiling.
1775                        Param: "sleep" - profile D-state sleeping (millisecs).
1776                                Requires CONFIG_SCHEDSTATS
1777                        Param: "kvm" - profile VM exits.
1778
1779        processor.max_cstate=   [HW,ACPI]
1780                        Limit processor to maximum C-state
1781                        max_cstate=9 overrides any DMI blacklist limit.
1782
1783        processor.nocst [HW,ACPI]
1784                        Ignore the _CST method to determine C-states,
1785                        instead using the legacy FADT method
1786
1787        prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1788                        before loading.
1789                        See Documentation/blockdev/ramdisk.txt.
1790
1791        psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1792                        probe for; one of (bare|imps|exps|lifebook|any).
1793        psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1794                        per second.
1795        psmouse.resetafter=     [HW,MOUSE]
1796                        Try to reset the device after so many bad packets
1797                        (0 = never).
1798        psmouse.resolution=
1799                        [HW,MOUSE] Set desired mouse resolution, in dpi.
1800        psmouse.smartscroll=
1801                        [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1802                        0 = disabled, 1 = enabled (default).
1803
1804        pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1805                        Format:
1806                        <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1807
1808        pt.             [PARIDE]
1809                        See Documentation/blockdev/paride.txt.
1810
1811        pty.legacy_count=
1812                        [KNL] Number of legacy pty's. Overwrites compiled-in
1813                        default number.
1814
1815        quiet           [KNL] Disable most log messages
1816
1817        r128=           [HW,DRM]
1818
1819        raid=           [HW,RAID]
1820                        See Documentation/md.txt.
1821
1822        ramdisk_blocksize=      [RAM]
1823                        See Documentation/blockdev/ramdisk.txt.
1824
1825        ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1826                        See Documentation/blockdev/ramdisk.txt.
1827
1828        rcupdate.blimit=        [KNL,BOOT]
1829                        Set maximum number of finished RCU callbacks to process
1830                        in one batch.
1831
1832        rcupdate.qhimark=       [KNL,BOOT]
1833                        Set threshold of queued
1834                        RCU callbacks over which batch limiting is disabled.
1835
1836        rcupdate.qlowmark=      [KNL,BOOT]
1837                        Set threshold of queued RCU callbacks below which
1838                        batch limiting is re-enabled.
1839
1840        rdinit=         [KNL]
1841                        Format: <full_path>
1842                        Run specified binary instead of /init from the ramdisk,
1843                        used for early userspace startup. See initrd.
1844
1845        reboot=         [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1846                        Format: <reboot_mode>[,<reboot_mode2>[,...]]
1847                        See arch/*/kernel/reboot.c or arch/*/kernel/process.c                   
1848
1849        relax_domain_level=
1850                        [KNL, SMP] Set scheduler's default relax_domain_level.
1851                        See Documentation/cpusets.txt.
1852
1853        reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1854
1855        reservetop=     [X86-32]
1856                        Format: nn[KMG]
1857                        Reserves a hole at the top of the kernel virtual
1858                        address space.
1859
1860        reset_devices   [KNL] Force drivers to reset the underlying device
1861                        during initialization.
1862
1863        resume=         [SWSUSP]
1864                        Specify the partition device for software suspend
1865
1866        resume_offset=  [SWSUSP]
1867                        Specify the offset from the beginning of the partition
1868                        given by "resume=" at which the swap header is located,
1869                        in <PAGE_SIZE> units (needed only for swap files).
1870                        See  Documentation/power/swsusp-and-swap-files.txt
1871
1872        retain_initrd   [RAM] Keep initrd memory after extraction
1873
1874        rhash_entries=  [KNL,NET]
1875                        Set number of hash buckets for route cache
1876
1877        riscom8=        [HW,SERIAL]
1878                        Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1879
1880        ro              [KNL] Mount root device read-only on boot
1881
1882        root=           [KNL] Root filesystem
1883
1884        rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1885                        mount the root filesystem
1886
1887        rootflags=      [KNL] Set root filesystem mount option string
1888
1889        rootfstype=     [KNL] Set root filesystem type
1890
1891        rootwait        [KNL] Wait (indefinitely) for root device to show up.
1892                        Useful for devices that are detected asynchronously
1893                        (e.g. USB and MMC devices).
1894
1895        root_plug.vendor_id=
1896                        [ROOTPLUG] Override the default vendor ID
1897
1898        root_plug.product_id=
1899                        [ROOTPLUG] Override the default product ID
1900
1901        root_plug.debug=
1902                        [ROOTPLUG] Enable debugging output
1903
1904        rw              [KNL] Mount root device read-write on boot
1905
1906        S               [KNL] Run init in single mode
1907
1908        sa1100ir        [NET]
1909                        See drivers/net/irda/sa1100_ir.c.
1910
1911        sbni=           [NET] Granch SBNI12 leased line adapter
1912
1913        sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1914                        Format: <io>[,<timeout>[,<isapnp>]]
1915
1916        scsi_debug_*=   [SCSI]
1917                        See drivers/scsi/scsi_debug.c.
1918
1919        scsi_default_dev_flags=
1920                        [SCSI] SCSI default device flags
1921                        Format: <integer>
1922
1923        scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1924                        Format: <vendor>:<model>:<flags>
1925                        (flags are integer value)
1926
1927        scsi_logging_level=     [SCSI] a bit mask of logging levels
1928                        See drivers/scsi/scsi_logging.h for bits.  Also
1929                        settable via sysctl at dev.scsi.logging_level
1930                        (/proc/sys/dev/scsi/logging_level).
1931                        There is also a nice 'scsi_logging_level' script in the
1932                        S390-tools package, available for download at
1933                        http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1934
1935        scsi_mod.scan=  [SCSI] sync (default) scans SCSI busses as they are
1936                        discovered.  async scans them in kernel threads,
1937                        allowing boot to proceed.  none ignores them, expecting
1938                        user space to do the scan.
1939
1940        selinux         [SELINUX] Disable or enable SELinux at boot time.
1941                        Format: { "0" | "1" }
1942                        See security/selinux/Kconfig help text.
1943                        0 -- disable.
1944                        1 -- enable.
1945                        Default value is set via kernel config option.
1946                        If enabled at boot time, /selinux/disable can be used
1947                        later to disable prior to initial policy load.
1948
1949        selinux_compat_net =
1950                        [SELINUX] Set initial selinux_compat_net flag value.
1951                        Format: { "0" | "1" }
1952                        0 -- use new secmark-based packet controls
1953                        1 -- use legacy packet controls
1954                        Default value is 0 (preferred).
1955                        Value can be changed at runtime via
1956                        /selinux/compat_net.
1957
1958        serialnumber    [BUGS=X86-32]
1959
1960        shapers=        [NET]
1961                        Maximal number of shapers.
1962
1963        show_msr=       [x86] show boot-time MSR settings
1964                        Format: { <integer> }
1965                        Show boot-time (BIOS-initialized) MSR settings.
1966                        The parameter means the number of CPUs to show,
1967                        for example 1 means boot CPU only.
1968
1969        sim710=         [SCSI,HW]
1970                        See header of drivers/scsi/sim710.c.
1971
1972        simeth=         [IA-64]
1973        simscsi=
1974
1975        slram=          [HW,MTD]
1976
1977        slub_debug[=options[,slabs]]    [MM, SLUB]
1978                        Enabling slub_debug allows one to determine the
1979                        culprit if slab objects become corrupted. Enabling
1980                        slub_debug can create guard zones around objects and
1981                        may poison objects when not in use. Also tracks the
1982                        last alloc / free. For more information see
1983                        Documentation/vm/slub.txt.
1984
1985        slub_max_order= [MM, SLUB]
1986                        Determines the maximum allowed order for slabs.
1987                        A high setting may cause OOMs due to memory
1988                        fragmentation. For more information see
1989                        Documentation/vm/slub.txt.
1990
1991        slub_min_objects=       [MM, SLUB]
1992                        The minimum number of objects per slab. SLUB will
1993                        increase the slab order up to slub_max_order to
1994                        generate a sufficiently large slab able to contain
1995                        the number of objects indicated. The higher the number
1996                        of objects the smaller the overhead of tracking slabs
1997                        and the less frequently locks need to be acquired.
1998                        For more information see Documentation/vm/slub.txt.
1999
2000        slub_min_order= [MM, SLUB]
2001                        Determines the mininum page order for slabs. Must be
2002                        lower than slub_max_order.
2003                        For more information see Documentation/vm/slub.txt.
2004
2005        slub_nomerge    [MM, SLUB]
2006                        Disable merging of slabs with similar size. May be
2007                        necessary if there is some reason to distinguish
2008                        allocs to different slabs. Debug options disable
2009                        merging on their own.
2010                        For more information see Documentation/vm/slub.txt.
2011
2012        smart2=         [HW]
2013                        Format: <io1>[,<io2>[,...,<io8>]]
2014
2015        smp-alt-once    [X86-32,SMP] On a hotplug CPU system, only
2016                        attempt to substitute SMP alternatives once at boot.
2017
2018        smsc-ircc2.nopnp        [HW] Don't use PNP to discover SMC devices
2019        smsc-ircc2.ircc_cfg=    [HW] Device configuration I/O port
2020        smsc-ircc2.ircc_sir=    [HW] SIR base I/O port
2021        smsc-ircc2.ircc_fir=    [HW] FIR base I/O port
2022        smsc-ircc2.ircc_irq=    [HW] IRQ line
2023        smsc-ircc2.ircc_dma=    [HW] DMA channel
2024        smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2025                                0: Toshiba Satellite 1800 (GP data pin select)
2026                                1: Fast pin select (default)
2027                                2: ATC IRMode
2028
2029        snd-ad1816a=    [HW,ALSA]
2030
2031        snd-ad1848=     [HW,ALSA]
2032
2033        snd-ali5451=    [HW,ALSA]
2034
2035        snd-als100=     [HW,ALSA]
2036
2037        snd-als4000=    [HW,ALSA]
2038
2039        snd-azt2320=    [HW,ALSA]
2040
2041        snd-cmi8330=    [HW,ALSA]
2042
2043        snd-cmipci=     [HW,ALSA]
2044
2045        snd-cs4231=     [HW,ALSA]
2046
2047        snd-cs4232=     [HW,ALSA]
2048
2049        snd-cs4236=     [HW,ALSA]
2050
2051        snd-cs4281=     [HW,ALSA]
2052
2053        snd-cs46xx=     [HW,ALSA]
2054
2055        snd-dt019x=     [HW,ALSA]
2056
2057        snd-dummy=      [HW,ALSA]
2058
2059        snd-emu10k1=    [HW,ALSA]
2060
2061        snd-ens1370=    [HW,ALSA]
2062
2063        snd-ens1371=    [HW,ALSA]
2064
2065        snd-es968=      [HW,ALSA]
2066
2067        snd-es1688=     [HW,ALSA]
2068
2069        snd-es18xx=     [HW,ALSA]
2070
2071        snd-es1938=     [HW,ALSA]
2072
2073        snd-es1968=     [HW,ALSA]
2074
2075        snd-fm801=      [HW,ALSA]
2076
2077        snd-gusclassic= [HW,ALSA]
2078
2079        snd-gusextreme= [HW,ALSA]
2080
2081        snd-gusmax=     [HW,ALSA]
2082
2083        snd-hdsp=       [HW,ALSA]
2084
2085        snd-ice1712=    [HW,ALSA]
2086
2087        snd-intel8x0=   [HW,ALSA]
2088
2089        snd-interwave=  [HW,ALSA]
2090
2091        snd-interwave-stb=
2092                        [HW,ALSA]
2093
2094        snd-korg1212=   [HW,ALSA]
2095
2096        snd-maestro3=   [HW,ALSA]
2097
2098        snd-mpu401=     [HW,ALSA]
2099
2100        snd-mtpav=      [HW,ALSA]
2101
2102        snd-nm256=      [HW,ALSA]
2103
2104        snd-opl3sa2=    [HW,ALSA]
2105
2106        snd-opti92x-ad1848=
2107                        [HW,ALSA]
2108
2109        snd-opti92x-cs4231=
2110                        [HW,ALSA]
2111
2112        snd-opti93x=    [HW,ALSA]
2113
2114        snd-pmac=       [HW,ALSA]
2115
2116        snd-rme32=      [HW,ALSA]
2117
2118        snd-rme96=      [HW,ALSA]
2119
2120        snd-rme9652=    [HW,ALSA]
2121
2122        snd-sb8=        [HW,ALSA]
2123
2124        snd-sb16=       [HW,ALSA]
2125
2126        snd-sbawe=      [HW,ALSA]
2127
2128        snd-serial=     [HW,ALSA]
2129
2130        snd-sgalaxy=    [HW,ALSA]
2131
2132        snd-sonicvibes= [HW,ALSA]
2133
2134        snd-sun-amd7930=
2135                        [HW,ALSA]
2136
2137        snd-sun-cs4231= [HW,ALSA]
2138
2139        snd-trident=    [HW,ALSA]
2140
2141        snd-usb-audio=  [HW,ALSA,USB]
2142
2143        snd-via82xx=    [HW,ALSA]
2144
2145        snd-virmidi=    [HW,ALSA]
2146
2147        snd-wavefront=  [HW,ALSA]
2148
2149        snd-ymfpci=     [HW,ALSA]
2150
2151        softlockup_panic=
2152                        [KNL] Should the soft-lockup detector generate panics.
2153
2154        sonypi.*=       [HW] Sony Programmable I/O Control Device driver
2155                        See Documentation/sonypi.txt
2156
2157        specialix=      [HW,SERIAL] Specialix multi-serial port adapter
2158                        See Documentation/serial/specialix.txt.
2159
2160        spia_io_base=   [HW,MTD]
2161        spia_fio_base=
2162        spia_pedr=
2163        spia_peddr=
2164
2165        sscape=         [HW,OSS]
2166                        Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2167
2168        st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
2169                        See Documentation/scsi/st.txt.
2170
2171        sti=            [PARISC,HW]
2172                        Format: <num>
2173                        Set the STI (builtin display/keyboard on the HP-PARISC
2174                        machines) console (graphic card) which should be used
2175                        as the initial boot-console.
2176                        See also comment in drivers/video/console/sticore.c.
2177
2178        sti_font=       [HW]
2179                        See comment in drivers/video/console/sticore.c.
2180
2181        stifb=          [HW]
2182                        Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2183
2184        sunrpc.pool_mode=
2185                        [NFS]
2186                        Control how the NFS server code allocates CPUs to
2187                        service thread pools.  Depending on how many NICs
2188                        you have and where their interrupts are bound, this
2189                        option will affect which CPUs will do NFS serving.
2190                        Note: this parameter cannot be changed while the
2191                        NFS server is running.
2192
2193                        auto        the server chooses an appropriate mode
2194                                    automatically using heuristics
2195                        global      a single global pool contains all CPUs
2196                        percpu      one pool for each CPU
2197                        pernode     one pool for each NUMA node (equivalent
2198                                    to global on non-NUMA machines)
2199
2200        swiotlb=        [IA-64] Number of I/O TLB slabs
2201
2202        switches=       [HW,M68k]
2203
2204        sym53c416=      [HW,SCSI]
2205                        See header of drivers/scsi/sym53c416.c.
2206
2207        sysrq_always_enabled
2208                        [KNL]
2209                        Ignore sysrq setting - this boot parameter will
2210                        neutralize any effect of /proc/sys/kernel/sysrq.
2211                        Useful for debugging.
2212
2213        t128=           [HW,SCSI]
2214                        See header of drivers/scsi/t128.c.
2215
2216        tdfx=           [HW,DRM]
2217
2218        test_suspend=   [SUSPEND]
2219                        Specify "mem" (for Suspend-to-RAM) or "standby" (for
2220                        standby suspend) as the system sleep state to briefly
2221                        enter during system startup.  The system is woken from
2222                        this state using a wakeup-capable RTC alarm.
2223
2224        thash_entries=  [KNL,NET]
2225                        Set number of hash buckets for TCP connection
2226
2227        thermal.act=    [HW,ACPI]
2228                        -1: disable all active trip points in all thermal zones
2229                        <degrees C>: override all lowest active trip points
2230
2231        thermal.crt=    [HW,ACPI]
2232                        -1: disable all critical trip points in all thermal zones
2233                        <degrees C>: override all critical trip points
2234
2235        thermal.nocrt=  [HW,ACPI]
2236                        Set to disable actions on ACPI thermal zone
2237                        critical and hot trip points.
2238
2239        thermal.off=    [HW,ACPI]
2240                        1: disable ACPI thermal control
2241
2242        thermal.psv=    [HW,ACPI]
2243                        -1: disable all passive trip points
2244                        <degrees C>: override all passive trip points to this value
2245
2246        thermal.tzp=    [HW,ACPI]
2247                        Specify global default ACPI thermal zone polling rate
2248                        <deci-seconds>: poll all this frequency
2249                        0: no polling (default)
2250
2251        tmscsim=        [HW,SCSI]
2252                        See comment before function dc390_setup() in
2253                        drivers/scsi/tmscsim.c.
2254
2255        tp720=          [HW,PS2]
2256
2257        trix=           [HW,OSS] MediaTrix AudioTrix Pro
2258                        Format:
2259                        <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2260
2261        turbografx.map[2|3]=    [HW,JOY]
2262                        TurboGraFX parallel port interface
2263                        Format:
2264                        <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2265                        See also Documentation/input/joystick-parport.txt
2266
2267        u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2268                        See header of drivers/scsi/u14-34f.c.
2269
2270        uart401=        [HW,OSS]
2271                        Format: <io>,<irq>
2272
2273        uart6850=       [HW,OSS]
2274                        Format: <io>,<irq>
2275
2276        uhci-hcd.ignore_oc=
2277                        [USB] Ignore overcurrent events (default N).
2278                        Some badly-designed motherboards generate lots of
2279                        bogus events, for ports that aren't wired to
2280                        anything.  Set this parameter to avoid log spamming.
2281                        Note that genuine overcurrent events won't be
2282                        reported either.
2283
2284        unknown_nmi_panic
2285                        [X86-32,X86-64]
2286                        Set unknown_nmi_panic=1 early on boot.
2287
2288        usbcore.autosuspend=
2289                        [USB] The autosuspend time delay (in seconds) used
2290                        for newly-detected USB devices (default 2).  This
2291                        is the time required before an idle device will be
2292                        autosuspended.  Devices for which the delay is set
2293                        to a negative value won't be autosuspended at all.
2294
2295        usbcore.usbfs_snoop=
2296                        [USB] Set to log all usbfs traffic (default 0 = off).
2297
2298        usbcore.blinkenlights=
2299                        [USB] Set to cycle leds on hubs (default 0 = off).
2300
2301        usbcore.old_scheme_first=
2302                        [USB] Start with the old device initialization
2303                        scheme (default 0 = off).
2304
2305        usbcore.use_both_schemes=
2306                        [USB] Try the other device initialization scheme
2307                        if the first one fails (default 1 = enabled).
2308
2309        usbcore.initial_descriptor_timeout=
2310                        [USB] Specifies timeout for the initial 64-byte
2311                        USB_REQ_GET_DESCRIPTOR request in milliseconds
2312                        (default 5000 = 5.0 seconds).
2313
2314        usbhid.mousepoll=
2315                        [USBHID] The interval which mice are to be polled at.
2316
2317        add_efi_memmap  [EFI; x86-32,X86-64] Include EFI memory map in
2318                        kernel's map of available physical RAM.
2319
2320        vdso=           [X86-32,SH,x86-64]
2321                        vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2322                        vdso=1: enable VDSO (default)
2323                        vdso=0: disable VDSO mapping
2324
2325        vdso32=         [X86-32,X86-64]
2326                        vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2327                        vdso32=1: enable 32-bit VDSO (default)
2328                        vdso32=0: disable 32-bit VDSO mapping
2329
2330        vector=         [IA-64,SMP]
2331                        vector=percpu: enable percpu vector domain
2332
2333        video=          [FB] Frame buffer configuration
2334                        See Documentation/fb/modedb.txt.
2335
2336        vga=            [BOOT,X86-32] Select a particular video mode
2337                        See Documentation/x86/i386/boot.txt and
2338                        Documentation/svga.txt.
2339                        Use vga=ask for menu.
2340                        This is actually a boot loader parameter; the value is
2341                        passed to the kernel using a special protocol.
2342
2343        vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2344                        size of <nn>. This can be used to increase the
2345                        minimum size (128MB on x86). It can also be used to
2346                        decrease the size and leave more room for directly
2347                        mapped kernel RAM.
2348
2349        vmhalt=         [KNL,S390] Perform z/VM CP command after system halt.
2350                        Format: <command>
2351
2352        vmpanic=        [KNL,S390] Perform z/VM CP command after kernel panic.
2353                        Format: <command>
2354
2355        vmpoff=         [KNL,S390] Perform z/VM CP command after power off.
2356                        Format: <command>
2357
2358        waveartist=     [HW,OSS]
2359                        Format: <io>,<irq>,<dma>,<dma2>
2360
2361        wd33c93=        [HW,SCSI]
2362                        See header of drivers/scsi/wd33c93.c.
2363
2364        wd7000=         [HW,SCSI]
2365                        See header of drivers/scsi/wd7000.c.
2366
2367        wdt=            [WDT] Watchdog
2368                        See Documentation/watchdog/wdt.txt.
2369
2370        xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2371        xd_geo=         See header of drivers/block/xd.c.
2372
2373        xirc2ps_cs=     [NET,PCMCIA]
2374                        Format:
2375                        <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2376
2377        norandmaps      Don't use address space randomization
2378                        Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2379
2380______________________________________________________________________
2381
2382TODO:
2383
2384        Add documentation for ALSA options.
2385        Add more DRM drivers.
2386
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