Documentation/kernel-parameters.txt

   1                           Kernel Parameters
   2                           ~~~~~~~~~~~~~~~~~
   3
   4 The 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
   7 case insensitive manner), and with descriptions where known.
   8
   9 Module parameters for loadable modules are specified only as the
  10 parameter name with optional '=' and value as appropriate, such as:
  11
  12         modprobe usbcore blinkenlights=1
  13
  14 Module parameters for modules that are built into the kernel image
  15 are 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
  20 This document may not be entirely up to date and comprehensive. The command
  21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  22 module. Loadable modules, after being loaded into the running kernel, also
  23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  24 parameters may be changed at runtime by the command
  25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  26
  27 The parameters listed below are only valid if certain kernel build options were
  28 enabled and if respective hardware is present. The text in square brackets at
  29 the beginning of each description states the restrictions within which a
  30 parameter is applicable:
  31
  32         ACPI    ACPI support is enabled.
  33         ALSA    ALSA sound support is enabled.
  34         APIC    APIC support is enabled.
  35         APM     Advanced Power Management support is enabled.
  36         AX25    Appropriate AX.25 support is enabled.
  37         CD      Appropriate CD support is enabled.
  38         DRM     Direct Rendering Management support is enabled.
  39         EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
  40         EFI     EFI Partitioning (GPT) is enabled
  41         EIDE    EIDE/ATAPI support is enabled.
  42         FB      The frame buffer device is enabled.
  43         HW      Appropriate hardware is enabled.
  44         IA-32   IA-32 aka i386 architecture is enabled.
  45         IA-64   IA-64 architecture is enabled.
  46         IOSCHED More than one I/O scheduler is enabled.
  47         IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
  48         ISAPNP  ISA PnP code is enabled.
  49         ISDN    Appropriate ISDN support is enabled.
  50         JOY     Appropriate joystick support is enabled.
  51         LIBATA  Libata driver is enabled
  52         LP      Printer support is enabled.
  53         LOOP    Loopback device support is enabled.
  54         M68k    M68k architecture is enabled.
  55                         These options have more detailed description inside of
  56                         Documentation/m68k/kernel-options.txt.
  57         MCA     MCA bus support is enabled.
  58         MDA     MDA console support is enabled.
  59         MOUSE   Appropriate mouse support is enabled.
  60         MSI     Message Signaled Interrupts (PCI).
  61         MTD     MTD support is enabled.
  62         NET     Appropriate network support is enabled.
  63         NUMA    NUMA support is enabled.
  64         GENERIC_TIME The generic timeofday code is enabled.
  65         NFS     Appropriate NFS support is enabled.
  66         OSS     OSS sound support is enabled.
  67         PV_OPS  A paravirtualized kernel
  68         PARIDE  The ParIDE subsystem is enabled.
  69         PARISC  The PA-RISC architecture is enabled.
  70         PCI     PCI bus support is enabled.
  71         PCMCIA  The PCMCIA subsystem is enabled.
  72         PNP     Plug & Play support is enabled.
  73         PPC     PowerPC architecture is enabled.
  74         PPT     Parallel port support is enabled.
  75         PS2     Appropriate PS/2 support is enabled.
  76         RAM     RAM disk support is enabled.
  77         S390    S390 architecture is enabled.
  78         SCSI    Appropriate SCSI support is enabled.
  79                         A lot of drivers has their options described inside of
  80                         Documentation/scsi/.
  81         SELINUX SELinux support is enabled.
  82         SERIAL  Serial support is enabled.
  83         SH      SuperH architecture is enabled.
  84         SMP     The kernel is an SMP kernel.
  85         SPARC   Sparc architecture is enabled.
  86         SWSUSP  Software suspend is enabled.
  87         TS      Appropriate touchscreen support is enabled.
  88         USB     USB support is enabled.
  89         USBHID  USB Human Interface Device support is enabled.
  90         V4L     Video For Linux support is enabled.
  91         VGA     The VGA console has been enabled.
  92         VT      Virtual terminal support is enabled.
  93         WDT     Watchdog support is enabled.
  94         XT      IBM PC/XT MFM hard disk support is enabled.
  95         X86-64  X86-64 architecture is enabled.
  96                         More X86-64 boot options can be found in
  97                         Documentation/x86_64/boot-options.txt .
  98
  99 In addition, the following text indicates that the option:
 100
 101         BUGS=   Relates to possible processor bugs on the said processor.
 102         KNL     Is a kernel start-up parameter.
 103         BOOT    Is a boot loader parameter.
 104
 105 Parameters denoted with BOOT are actually interpreted by the boot
 106 loader, and have no meaning to the kernel directly.
 107 Do not modify the syntax of boot loader parameters without extreme
 108 need or coordination with <Documentation/i386/boot.txt>.
 109
 110 There are also arch-specific kernel-parameters not documented here.
 111 See for example <Documentation/x86_64/boot-options.txt>.
 112
 113 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
 114 a trailing = on the name of any parameter states that that parameter will
 115 be entered as an environment variable, whereas its absence indicates that
 116 it will appear as a kernel argument readable via /proc/cmdline by programs
 117 running once the system is up.
 118
 119 The number of kernel parameters is not limited, but the length of the
 120 complete command line (parameters including spaces etc.) is limited to
 121 a fixed number of characters. This limit depends on the architecture
 122 and is between 256 and 4096 characters. It is defined in the file
 123 ./include/asm/setup.h as COMMAND_LINE_SIZE.
 124
 125
 126         53c7xx=         [HW,SCSI] Amiga SCSI controllers
 127                         See header of drivers/scsi/53c7xx.c.
 128                         See also Documentation/scsi/ncr53c7xx.txt.
 129
 130         acpi=           [HW,ACPI,X86-64,i386]
 131                         Advanced Configuration and Power Interface
 132                         Format: { force | off | ht | strict | noirq }
 133                         force -- enable ACPI if default was off
 134                         off -- disable ACPI if default was on
 135                         noirq -- do not use ACPI for IRQ routing
 136                         ht -- run only enough ACPI to enable Hyper Threading
 137                         strict -- Be less tolerant of platforms that are not
 138                                 strictly ACPI specification compliant.
 139
 140                         See also Documentation/pm.txt, pci=noacpi
 141
 142         acpi_apic_instance=     [ACPI, IOAPIC]
 143                         Format: <int>
 144                         2: use 2nd APIC table, if available
 145                         1,0: use 1st APIC table
 146                         default: 0
 147
 148         acpi_sleep=     [HW,ACPI] Sleep options
 149                         Format: { s3_bios, s3_mode }
 150                         See Documentation/power/video.txt
 151
 152         acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 153                         Format: { level | edge | high | low }
 154
 155         acpi_irq_balance [HW,ACPI]
 156                         ACPI will balance active IRQs
 157                         default in APIC mode
 158
 159         acpi_irq_nobalance [HW,ACPI]
 160                         ACPI will not move active IRQs (default)
 161                         default in PIC mode
 162
 163         acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
 164                         use by PCI
 165                         Format: <irq>,<irq>...
 166
 167         acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
 168                         Format: <irq>,<irq>...
 169
 170         acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
 171                         Format: To spoof as Windows 98: ="Microsoft Windows"
 172
 173         acpi_osi=       [HW,ACPI] Modify list of supported OS interface strings
 174                         acpi_osi="string1"      # add string1 -- only one string
 175                         acpi_osi="!string2"     # remove built-in string2
 176                         acpi_osi=               # disable all strings
 177
 178         acpi_serialize  [HW,ACPI] force serialization of AML methods
 179
 180         acpi_skip_timer_override [HW,ACPI]
 181                         Recognize and ignore IRQ0/pin2 Interrupt Override.
 182                         For broken nForce2 BIOS resulting in XT-PIC timer.
 183         acpi_use_timer_override [HW,ACPI}
 184                         Use timer override. For some broken Nvidia NF5 boards
 185                         that require a timer override, but don't have
 186                         HPET
 187
 188         acpi.debug_layer=       [HW,ACPI]
 189                         Format: <int>
 190                         Each bit of the <int> indicates an ACPI debug layer,
 191                         1: enable, 0: disable. It is useful for boot time
 192                         debugging. After system has booted up, it can be set
 193                         via /sys/module/acpi/parameters/debug_layer.
 194                         CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
 195                         Available bits (add the numbers together) to enable debug output
 196                         for specific parts of the ACPI subsystem:
 197                         0x01 utilities 0x02 hardware 0x04 events 0x08 tables
 198                         0x10 namespace 0x20 parser 0x40 dispatcher
 199                         0x80 executer 0x100 resources 0x200 acpica debugger
 200                         0x400 os services 0x800 acpica disassembler.
 201                         The number can be in decimal or prefixed with 0x in hex.
 202                         Warning: Many of these options can produce a lot of
 203                         output and make your system unusable. Be very careful.
 204
 205         acpi.debug_level=       [HW,ACPI]
 206                         Format: <int>
 207                         Each bit of the <int> indicates an ACPI debug level,
 208                         1: enable, 0: disable. It is useful for boot time
 209                         debugging. After system has booted up, it can be set
 210                         via /sys/module/acpi/parameters/debug_level.
 211                         CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
 212                         Available bits (add the numbers together) to enable different
 213                         debug output levels of the ACPI subsystem:
 214                         0x01 error 0x02 warn 0x04 init 0x08 debug object
 215                         0x10 info 0x20 init names 0x40 parse 0x80 load
 216                         0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
 217                         0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
 218                         0x10000 resources 0x20000 user requests 0x40000 package.
 219                         The number can be in decimal or prefixed with 0x in hex.
 220                         Warning: Many of these options can produce a lot of
 221                         output and make your system unusable. Be very careful.
 222
 223
 224         acpi_fake_ecdt  [HW,ACPI] Workaround failure due to BIOS lacking ECDT
 225
 226         acpi_pm_good    [IA-32,X86-64]
 227                         Override the pmtimer bug detection: force the kernel
 228                         to assume that this machine's pmtimer latches its value
 229                         and always returns good values.
 230
 231         enable_timer_pin_1 [i386,x86-64]
 232                         Enable PIN 1 of APIC timer
 233                         Can be useful to work around chipset bugs
 234                         (in particular on some ATI chipsets).
 235                         The kernel tries to set a reasonable default.
 236
 237         disable_timer_pin_1 [i386,x86-64]
 238                         Disable PIN 1 of APIC timer
 239                         Can be useful to work around chipset bugs.
 240
 241         ad1816=         [HW,OSS]
 242                         Format: <io>,<irq>,<dma>,<dma2>
 243                         See also Documentation/sound/oss/AD1816.
 244
 245         ad1848=         [HW,OSS]
 246                         Format: <io>,<irq>,<dma>,<dma2>,<type>
 247
 248         adlib=          [HW,OSS]
 249                         Format: <io>
 250
 251         advansys=       [HW,SCSI]
 252                         See header of drivers/scsi/advansys.c.
 253
 254         advwdt=         [HW,WDT] Advantech WDT
 255                         Format: <iostart>,<iostop>
 256
 257         aedsp16=        [HW,OSS] Audio Excel DSP 16
 258                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 259                         See also header of sound/oss/aedsp16.c.
 260
 261         aha152x=        [HW,SCSI]
 262                         See Documentation/scsi/aha152x.txt.
 263
 264         aha1542=        [HW,SCSI]
 265                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 266
 267         aic7xxx=        [HW,SCSI]
 268                         See Documentation/scsi/aic7xxx.txt.
 269
 270         aic79xx=        [HW,SCSI]
 271                         See Documentation/scsi/aic79xx.txt.
 272
 273         amijoy.map=     [HW,JOY] Amiga joystick support
 274                         Map of devices attached to JOY0DAT and JOY1DAT
 275                         Format: <a>,<b>
 276                         See also Documentation/kernel/input/joystick.txt
 277
 278         analog.map=     [HW,JOY] Analog joystick and gamepad support
 279                         Specifies type or capabilities of an analog joystick
 280                         connected to one of 16 gameports
 281                         Format: <type1>,<type2>,..<type16>
 282
 283         apc=            [HW,SPARC]
 284                         Power management functions (SPARCstation-4/5 + deriv.)
 285                         Format: noidle
 286                         Disable APC CPU standby support. SPARCstation-Fox does
 287                         not play well with APC CPU idle - disable it if you have
 288                         APC and your system crashes randomly.
 289
 290         apic=           [APIC,i386] Change the output verbosity whilst booting
 291                         Format: { quiet (default) | verbose | debug }
 292                         Change the amount of debugging information output
 293                         when initialising the APIC and IO-APIC components.
 294
 295         apm=            [APM] Advanced Power Management
 296                         See header of arch/i386/kernel/apm.c.
 297
 298         applicom=       [HW]
 299                         Format: <mem>,<irq>
 300
 301         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 302                         Format: <io>,<irq>,<nodeID>
 303
 304         ataflop=        [HW,M68k]
 305
 306         atarimouse=     [HW,MOUSE] Atari Mouse
 307
 308         atascsi=        [HW,SCSI] Atari SCSI
 309
 310         atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 311                         EzKey and similar keyboards
 312
 313         atkbd.reset=    [HW] Reset keyboard during initialization
 314
 315         atkbd.set=      [HW] Select keyboard code set
 316                         Format: <int> (2 = AT (default), 3 = PS/2)
 317
 318         atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 319                         keyboards
 320
 321         atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 322                         Format: <bool> (0 = real, 1 = synthetic (default))
 323
 324         atkbd.softrepeat= [HW]
 325                         Use software keyboard repeat
 326
 327         autotest        [IA64]
 328
 329         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 330                         Format: <io>,0x79 (?)
 331
 332         baycom_epp=     [HW,AX25]
 333                         Format: <io>,<mode>
 334
 335         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 336                         Format: <io>,<mode>
 337                         See header of drivers/net/hamradio/baycom_par.c.
 338
 339         baycom_ser_fdx= [HW,AX25]
 340                         BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 341                         Format: <io>,<irq>,<mode>[,<baud>]
 342                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 343
 344         baycom_ser_hdx= [HW,AX25]
 345                         BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 346                         Format: <io>,<irq>,<mode>
 347                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 348
 349         blkmtd_device=  [HW,MTD]
 350         blkmtd_erasesz=
 351         blkmtd_ro=
 352         blkmtd_bs=
 353         blkmtd_count=
 354
 355         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 356         bttv.radio=     Most important insmod options are available as
 357                         kernel args too.
 358         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 359         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 360
 361         BusLogic=       [HW,SCSI]
 362                         See drivers/scsi/BusLogic.c, comment before function
 363                         BusLogic_ParseDriverOptions().
 364
 365         c101=           [NET] Moxa C101 synchronous serial card
 366
 367         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 368                         Sometimes CPU hardware bugs make them report the cache
 369                         size incorrectly. The kernel will attempt work arounds
 370                         to fix known problems, but for some CPUs it is not
 371                         possible to determine what the correct size should be.
 372                         This option provides an override for these situations.
 373
 374         cdu31a=         [HW,CD]
 375                         Format: <io>,<irq>[,PAS]
 376                         See header of drivers/cdrom/cdu31a.c.
 377
 378         chandev=        [HW,NET] Generic channel device initialisation
 379
 380         checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 381                         Format: { "0" | "1" }
 382                         See security/selinux/Kconfig help text.
 383                         0 -- check protection applied by kernel (includes
 384                                 any implied execute protection).
 385                         1 -- check protection requested by application.
 386                         Default value is set via a kernel config option.
 387                         Value can be changed at runtime via
 388                                 /selinux/checkreqprot.
 389
 390         clock=          [BUGS=IA-32, HW] gettimeofday clocksource override.
 391                         [Deprecated]
 392                         Forces specified clocksource (if available) to be used
 393                         when calculating gettimeofday(). If specified
 394                         clocksource is not available, it defaults to PIT.
 395                         Format: { pit | tsc | cyclone | pmtmr }
 396
 397         clocksource=    [GENERIC_TIME] Override the default clocksource
 398                         Format: <string>
 399                         Override the default clocksource and use the clocksource
 400                         with the name specified.
 401                         Some clocksource names to choose from, depending on
 402                         the platform:
 403                         [all] jiffies (this is the base, fallback clocksource)
 404                         [ACPI] acpi_pm
 405                         [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
 406                                 pxa_timer,timer3,32k_counter,timer0_1
 407                         [AVR32] avr32
 408                         [IA-32] pit,hpet,tsc,vmi-timer;
 409                                 scx200_hrt on Geode; cyclone on IBM x440
 410                         [MIPS] MIPS
 411                         [PARISC] cr16
 412                         [S390] tod
 413                         [SH] SuperH
 414                         [SPARC64] tick
 415                         [X86-64] hpet,tsc
 416
 417         code_bytes      [IA32] How many bytes of object code to print in an
 418                         oops report.
 419                         Range: 0 - 8192
 420                         Default: 64
 421
 422         disable_8254_timer
 423         enable_8254_timer
 424                         [IA32/X86_64] Disable/Enable interrupt 0 timer routing
 425                         over the 8254 in addition to over the IO-APIC. The
 426                         kernel tries to set a sensible default.
 427
 428         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
 429                         Format: disable
 430
 431         cm206=          [HW,CD]
 432                         Format: { auto | [<io>,][<irq>] }
 433
 434         com20020=       [HW,NET] ARCnet - COM20020 chipset
 435                         Format:
 436                         <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 437
 438         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 439                         Format: <io>[,<irq>]
 440
 441         com90xx=        [HW,NET]
 442                         ARCnet - COM90xx chipset (memory-mapped buffers)
 443                         Format: <io>[,<irq>[,<memstart>]]
 444
 445         condev=         [HW,S390] console device
 446         conmode=
 447
 448         console=        [KNL] Output console device and options.
 449
 450                 tty<n>  Use the virtual console device <n>.
 451
 452                 ttyS<n>[,options]
 453                 ttyUSB0[,options]
 454                         Use the specified serial port.  The options are of
 455                         the form "bbbbpnf", where "bbbb" is the baud rate,
 456                         "p" is parity ("n", "o", or "e"), "n" is number of
 457                         bits, and "f" is flow control ("r" for RTS or
 458                         omit it).  Default is "9600n8".
 459
 460                         See Documentation/serial-console.txt for more
 461                         information.  See
 462                         Documentation/networking/netconsole.txt for an
 463                         alternative.
 464
 465                 uart[8250],io,<addr>[,options]
 466                 uart[8250],mmio,<addr>[,options]
 467                         Start an early, polled-mode console on the 8250/16550
 468                         UART at the specified I/O port or MMIO address,
 469                         switching to the matching ttyS device later.  The
 470                         options are the same as for ttyS, above.
 471
 472         earlycon=       [KNL] Output early console device and options.
 473                 uart[8250],io,<addr>[,options]
 474                 uart[8250],mmio,<addr>[,options]
 475                         Start an early, polled-mode console on the 8250/16550
 476                         UART at the specified I/O port or MMIO address.
 477                         The options are the same as for ttyS, above.
 478
 479         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 480                         Format:
 481                         <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 482
 483         cpia_pp=        [HW,PPT]
 484                         Format: { parport<nr> | auto | none }
 485
 486         crashkernel=nn[KMG]@ss[KMG]
 487                         [KNL] Reserve a chunk of physical memory to
 488                         hold a kernel to switch to with kexec on panic.
 489
 490         cs4232=         [HW,OSS]
 491                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 492
 493         cs89x0_dma=     [HW,NET]
 494                         Format: <dma>
 495
 496         cs89x0_media=   [HW,NET]
 497                         Format: { rj45 | aui | bnc }
 498
 499         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 500
 501         dasd=           [HW,NET]
 502                         See header of drivers/s390/block/dasd_devmap.c.
 503
 504         db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 505                         (one device per port)
 506                         Format: <port#>,<type>
 507                         See also Documentation/input/joystick-parport.txt
 508
 509         debug           [KNL] Enable kernel debugging (events log level).
 510
 511         debug_locks_verbose=
 512                         [KNL] verbose self-tests
 513                         Format=<0|1>
 514                         Print debugging info while doing the locking API
 515                         self-tests.
 516                         We default to 0 (no extra messages), setting it to
 517                         1 will print _a lot_ more information - normally
 518                         only useful to kernel developers.
 519
 520         decnet=         [HW,NET]
 521                         Format: <area>[,<node>]
 522                         See also Documentation/networking/decnet.txt.
 523
 524         default_blu=    [VT]
 525                         Format: <blue0>,<blue1>,<blue2>,...,<blue15>
 526                         Change the default blue palette of the console.
 527                         This is a 16-member array composed of values
 528                         ranging from 0-255.
 529
 530         default_grn=    [VT]
 531                         Format: <green0>,<green1>,<green2>,...,<green15>
 532                         Change the default green palette of the console.
 533                         This is a 16-member array composed of values
 534                         ranging from 0-255.
 535
 536         default_red=    [VT]
 537                         Format: <red0>,<red1>,<red2>,...,<red15>
 538                         Change the default red palette of the console.
 539                         This is a 16-member array composed of values
 540                         ranging from 0-255.
 541
 542         default_utf8=   [VT]
 543                         Format=<0|1>
 544                         Set system-wide default UTF-8 mode for all tty's.
 545                         Default is 0 and by setting to 1, it enables UTF-8
 546                         mode for all newly opened or allocated terminals.
 547
 548         dhash_entries=  [KNL]
 549                         Set number of hash buckets for dentry cache.
 550
 551         digi=           [HW,SERIAL]
 552                         IO parameters + enable/disable command.
 553
 554         digiepca=       [HW,SERIAL]
 555                         See drivers/char/README.epca and
 556                         Documentation/digiepca.txt.
 557
 558         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 559                         support available.
 560                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 561
 562         dmasound=       [HW,OSS] Sound subsystem buffers
 563
 564         dscc4.setup=    [NET]
 565
 566         dtc3181e=       [HW,SCSI]
 567
 568         earlyprintk=    [IA-32,X86-64,SH]
 569                         earlyprintk=vga
 570                         earlyprintk=serial[,ttySn[,baudrate]]
 571
 572                         Append ",keep" to not disable it when the real console
 573                         takes over.
 574
 575                         Only vga or serial at a time, not both.
 576
 577                         Currently only ttyS0 and ttyS1 are supported.
 578
 579                         Interaction with the standard serial driver is not
 580                         very good.
 581
 582                         The VGA output is eventually overwritten by the real
 583                         console.
 584
 585         eata=           [HW,SCSI]
 586
 587         ec_intr=        [HW,ACPI] ACPI Embedded Controller interrupt mode
 588                         Format: <int>
 589                         0: polling mode
 590                         non-0: interrupt mode (default)
 591
 592         eda=            [HW,PS2]
 593
 594         edb=            [HW,PS2]
 595
 596         edd=            [EDD]
 597                         Format: {"of[f]" | "sk[ipmbr]"}
 598                         See comment in arch/i386/boot/edd.S
 599
 600         eicon=          [HW,ISDN]
 601                         Format: <id>,<membase>,<irq>
 602
 603         eisa_irq_edge=  [PARISC,HW]
 604                         See header of drivers/parisc/eisa.c.
 605
 606         elanfreq=       [IA-32]
 607                         See comment before function elanfreq_setup() in
 608                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 609
 610         elevator=       [IOSCHED]
 611                         Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
 612                         See Documentation/block/as-iosched.txt and
 613                         Documentation/block/deadline-iosched.txt for details.
 614
 615         elfcorehdr=     [IA-32, X86_64]
 616                         Specifies physical address of start of kernel core
 617                         image elf header. Generally kexec loader will
 618                         pass this option to capture kernel.
 619                         See Documentation/kdump/kdump.txt for details.
 620
 621         enforcing       [SELINUX] Set initial enforcing status.
 622                         Format: {"0" | "1"}
 623                         See security/selinux/Kconfig help text.
 624                         0 -- permissive (log only, no denials).
 625                         1 -- enforcing (deny and log).
 626                         Default value is 0.
 627                         Value can be changed at runtime via /selinux/enforce.
 628
 629         es1371=         [HW,OSS]
 630                         Format: <spdif>,[<nomix>,[<amplifier>]]
 631                         See also header of sound/oss/es1371.c.
 632
 633         ether=          [HW,NET] Ethernet cards parameters
 634                         This option is obsoleted by the "netdev=" option, which
 635                         has equivalent usage. See its documentation for details.
 636
 637         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 638                         Format: <io>[,<irq>]
 639
 640         failslab=
 641         fail_page_alloc=
 642         fail_make_request=[KNL]
 643                         General fault injection mechanism.
 644                         Format: <interval>,<probability>,<space>,<times>
 645                         See also /Documentation/fault-injection/.
 646
 647         fd_mcs=         [HW,SCSI]
 648                         See header of drivers/scsi/fd_mcs.c.
 649
 650         fdomain=        [HW,SCSI]
 651                         See header of drivers/scsi/fdomain.c.
 652
 653         floppy=         [HW]
 654                         See Documentation/floppy.txt.
 655
 656         gamecon.map[2|3]=
 657                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 658                         support via parallel port (up to 5 devices per port)
 659                         Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 660                         See also Documentation/input/joystick-parport.txt
 661
 662         gamma=          [HW,DRM]
 663
 664         gdth=           [HW,SCSI]
 665                         See header of drivers/scsi/gdth.c.
 666
 667         gpt             [EFI] Forces disk with valid GPT signature but
 668                         invalid Protective MBR to be treated as GPT.
 669
 670         gscd=           [HW,CD]
 671                         Format: <io>
 672
 673         gvp11=          [HW,SCSI]
 674
 675         hashdist=       [KNL,NUMA] Large hashes allocated during boot
 676                         are distributed across NUMA nodes.  Defaults on
 677                         for IA-64, off otherwise.
 678                         Format: 0 | 1 (for off | on)
 679
 680         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 681
 682         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 683                         Format: <cyl>,<head>,<sect>
 684
 685         hd?=            [HW] (E)IDE subsystem
 686         hd?lun=         See Documentation/ide.txt.
 687
 688         highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 689                         size of <nn>. This works even on boxes that have no
 690                         highmem otherwise. This also works to reduce highmem
 691                         size on bigger boxes.
 692
 693         highres=        [KNL] Enable/disable high resolution timer mode.
 694                         Valid parameters: "on", "off"
 695                         Default: "on"
 696
 697         hisax=          [HW,ISDN]
 698                         See Documentation/isdn/README.HiSax.
 699
 700         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 701
 702         i8042.direct    [HW] Put keyboard port into non-translated mode
 703         i8042.dumbkbd   [HW] Pretend that controller can only read data from
 704                              keyboard and cannot control its state
 705                              (Don't attempt to blink the leds)
 706         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 707         i8042.nokbd     [HW] Don't check/create keyboard port
 708         i8042.nomux     [HW] Don't check presence of an active multiplexing
 709                              controller
 710         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 711                              controllers
 712         i8042.panicblink=
 713                         [HW] Frequency with which keyboard LEDs should blink
 714                              when kernel panics (default is 0.5 sec)
 715         i8042.reset     [HW] Reset the controller during init and cleanup
 716         i8042.unlock    [HW] Unlock (ignore) the keylock
 717
 718         i810=           [HW,DRM]
 719
 720         i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 721                         indicates that the driver is running on unsupported
 722                         hardware.
 723         i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 724                         does not match list of supported models.
 725         i8k.power_status
 726                         [HW] Report power status in /proc/i8k
 727                         (disabled by default)
 728         i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 729                         capability is set.
 730
 731         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 732                         See Documentation/mca.txt.
 733
 734         icn=            [HW,ISDN]
 735                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 736
 737         ide=            [HW] (E)IDE subsystem
 738                         Format: ide=nodma or ide=doubler or ide=reverse
 739                         See Documentation/ide.txt.
 740
 741         ide?=           [HW] (E)IDE subsystem
 742                         Format: ide?=noprobe or chipset specific parameters.
 743                         See Documentation/ide.txt.
 744
 745         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 746                         See Documentation/ide.txt.
 747
 748         idle=           [X86]
 749                         Format: idle=poll or idle=mwait
 750                         Poll forces a polling idle loop that can slightly improves the performance
 751                         of waking up a idle CPU, but will use a lot of power and make the system
 752                         run hot. Not recommended.
 753                         idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
 754                         to not use it because it doesn't save as much power as a normal idle
 755                         loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
 756                         as idle=poll.
 757
 758         ignore_loglevel [KNL]
 759                         Ignore loglevel setting - this will print /all/
 760                         kernel messages to the console. Useful for debugging.
 761
 762         ihash_entries=  [KNL]
 763                         Set number of hash buckets for inode cache.
 764
 765         in2000=         [HW,SCSI]
 766                         See header of drivers/scsi/in2000.c.
 767
 768         init=           [KNL]
 769                         Format: <full_path>
 770                         Run specified binary instead of /sbin/init as init
 771                         process.
 772
 773         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 774                         for working out where the kernel is dying during
 775                         startup.
 776
 777         initrd=         [BOOT] Specify the location of the initial ramdisk
 778
 779         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 780                         Format: <irq>
 781
 782         inttest=        [IA64]
 783
 784         io7=            [HW] IO7 for Marvel based alpha systems
 785                         See comment before marvel_specify_io7 in
 786                         arch/alpha/kernel/core_marvel.c.
 787
 788         ip=             [IP_PNP]
 789                         See Documentation/nfsroot.txt.
 790
 791         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 792                         See comment before ip2_setup() in drivers/char/ip2.c.
 793
 794         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 795                         See header of drivers/scsi/ips.c.
 796
 797         ports=          [IP_VS_FTP] IPVS ftp helper module
 798                         Default is 21.
 799                         Up to 8 (IP_VS_APP_MAX_PORTS) ports
 800                         may be specified.
 801                         Format: <port>,<port>....
 802
 803         irqfixup        [HW]
 804                         When an interrupt is not handled search all handlers
 805                         for it. Intended to get systems with badly broken
 806                         firmware running.
 807
 808         irqpoll         [HW]
 809                         When an interrupt is not handled search all handlers
 810                         for it. Also check all handlers each timer
 811                         interrupt. Intended to get systems with badly broken
 812                         firmware running.
 813
 814         isapnp=         [ISAPNP]
 815                         Format: <RDP>,<reset>,<pci_scan>,<verbosity>
 816
 817         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 818                         Format:
 819                         <cpu number>,...,<cpu number>
 820                         or
 821                         <cpu number>-<cpu number>  (must be a positive range in ascending order)
 822                         or a mixture
 823                         <cpu number>,...,<cpu number>-<cpu number>
 824                         This option can be used to specify one or more CPUs
 825                         to isolate from the general SMP balancing and scheduling
 826                         algorithms. The only way to move a process onto or off
 827                         an "isolated" CPU is via the CPU affinity syscalls.
 828                         <cpu number> begins at 0 and the maximum value is
 829                         "number of CPUs in system - 1".
 830
 831                         This option is the preferred way to isolate CPUs. The
 832                         alternative -- manually setting the CPU mask of all
 833                         tasks in the system -- can cause problems and
 834                         suboptimal load balancer performance.
 835
 836         isp16=          [HW,CD]
 837                         Format: <io>,<irq>,<dma>,<setup>
 838
 839         iucv=           [HW,NET]
 840
 841         js=             [HW,JOY] Analog joystick
 842                         See Documentation/input/joystick.txt.
 843
 844         keepinitrd      [HW,ARM]
 845
 846         kstack=N        [IA-32,X86-64] Print N words from the kernel stack
 847                         in oops dumps.
 848
 849         l2cr=           [PPC]
 850
 851         lapic           [IA-32,APIC] Enable the local APIC even if BIOS
 852                         disabled it.
 853
 854         lapic_timer_c2_ok       [IA-32,x86-64,APIC] trust the local apic timer in
 855                         C2 power state.
 856
 857         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 858                         Format: addr:<io>,irq:<irq>
 859
 860         legacy_serial.force [HW,IA-32,X86-64]
 861                         Probe for COM ports at legacy addresses even
 862                         if PNPBIOS or ACPI should describe them.  This
 863                         is for working around firmware defects.
 864
 865         llsc*=          [IA64] See function print_params() in
 866                         arch/ia64/sn/kernel/llsc4.c.
 867
 868         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 869                         See Documentation/ramdisk.txt.
 870
 871         lockd.nlm_grace_period=P  [NFS] Assign grace period.
 872                         Format: <integer>
 873
 874         lockd.nlm_tcpport=N     [NFS] Assign TCP port.
 875                         Format: <integer>
 876
 877         lockd.nlm_timeout=T     [NFS] Assign timeout value.
 878                         Format: <integer>
 879
 880         lockd.nlm_udpport=M     [NFS] Assign UDP port.
 881                         Format: <integer>
 882
 883         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 884                         Format: <irq>
 885
 886         loglevel=       All Kernel Messages with a loglevel smaller than the
 887                         console loglevel will be printed to the console. It can
 888                         also be changed with klogd or other programs. The
 889                         loglevels are defined as follows:
 890
 891                         0 (KERN_EMERG)          system is unusable
 892                         1 (KERN_ALERT)          action must be taken immediately
 893                         2 (KERN_CRIT)           critical conditions
 894                         3 (KERN_ERR)            error conditions
 895                         4 (KERN_WARNING)        warning conditions
 896                         5 (KERN_NOTICE)         normal but significant condition
 897                         6 (KERN_INFO)           informational
 898                         7 (KERN_DEBUG)          debug-level messages
 899
 900         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 901                         Format: { n | nk | nM }
 902                         n must be a power of two.  The default size
 903                         is set in the kernel config file.
 904
 905         lp=0            [LP]    Specify parallel ports to use, e.g,
 906         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 907         lp=reset                first parallel port). 'lp=0' disables the
 908         lp=auto                 printer driver. 'lp=reset' (which can be
 909                                 specified in addition to the ports) causes
 910                                 attached printers to be reset. Using
 911                                 lp=port1,port2,... specifies the parallel ports
 912                                 to associate lp devices with, starting with
 913                                 lp0. A port specification may be 'none' to skip
 914                                 that lp device, or a parport name such as
 915                                 'parport0'. Specifying 'lp=auto' instead of a
 916                                 port specification list means that device IDs
 917                                 from each port should be examined, to see if
 918                                 an IEEE 1284-compliant printer is attached; if
 919                                 so, the driver will manage that printer.
 920                                 See also header of drivers/char/lp.c.
 921
 922         lpj=n           [KNL]
 923                         Sets loops_per_jiffy to given constant, thus avoiding
 924                         time-consuming boot-time autodetection (up to 250 ms per
 925                         CPU). 0 enables autodetection (default). To determine
 926                         the correct value for your kernel, boot with normal
 927                         autodetection and see what value is printed. Note that
 928                         on SMP systems the preset will be applied to all CPUs,
 929                         which is likely to cause problems if your CPUs need
 930                         significantly divergent settings. An incorrect value
 931                         will cause delays in the kernel to be wrong, leading to
 932                         unpredictable I/O errors and other breakage. Although
 933                         unlikely, in the extreme case this might damage your
 934                         hardware.
 935
 936         ltpc=           [NET]
 937                         Format: <io>,<irq>,<dma>
 938
 939         mac5380=        [HW,SCSI] Format:
 940                         <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 941
 942         mac53c9x=       [HW,SCSI] Format:
 943                         <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 944
 945         machvec=        [IA64] Force the use of a particular machine-vector
 946                         (machvec) in a generic kernel.
 947                         Example: machvec=hpzx1_swiotlb
 948
 949         max_loop=       [LOOP] Maximum number of loopback devices that can
 950                         be mounted
 951                         Format: <1-256>
 952
 953         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 954                         should make use of.
 955                         Using "nosmp" or "maxcpus=0" will disable SMP
 956                         entirely (the MPS table probe still happens, though).
 957                         A command-line option of "maxcpus=<NUM>", where <NUM>
 958                         is an integer greater than 0, limits the maximum number
 959                         of CPUs activated in SMP mode to <NUM>.
 960                         Using "maxcpus=1" on an SMP kernel is the trivial
 961                         case of an SMP kernel with only one CPU.
 962
 963         max_addr=[KMG]  [KNL,BOOT,ia64] All physical memory greater than or
 964                         equal to this physical address is ignored.
 965
 966         max_luns=       [SCSI] Maximum number of LUNs to probe.
 967                         Should be between 1 and 2^32-1.
 968
 969         max_report_luns=
 970                         [SCSI] Maximum number of LUNs received.
 971                         Should be between 1 and 16384.
 972
 973         mca-pentium     [BUGS=IA-32]
 974
 975         mcatest=        [IA-64]
 976
 977         mcd=            [HW,CD]
 978                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 979
 980         mcdx=           [HW,CD]
 981
 982         mce             [IA-32] Machine Check Exception
 983
 984         md=             [HW] RAID subsystems devices and level
 985                         See Documentation/md.txt.
 986
 987         mdacon=         [MDA]
 988                         Format: <first>,<last>
 989                         Specifies range of consoles to be captured by the MDA.
 990
 991         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 992                         Amount of memory to be used when the kernel is not able
 993                         to see the whole system memory or for test.
 994                         [IA-32] Use together with memmap= to avoid physical
 995                         address space collisions. Without memmap= PCI devices
 996                         could be placed at addresses belonging to unused RAM.
 997
 998         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 999                         memory.
1000
1001         memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1002                         E820 memory map, as specified by the user.
1003                         Such memmap=exactmap lines can be constructed based on
1004                         BIOS output or other requirements. See the memmap=nn@ss
1005                         option description.
1006
1007         memmap=nn[KMG]@ss[KMG]
1008                         [KNL] Force usage of a specific region of memory
1009                         Region of memory to be used, from ss to ss+nn.
1010
1011         memmap=nn[KMG]#ss[KMG]
1012                         [KNL,ACPI] Mark specific memory as ACPI data.
1013                         Region of memory to be used, from ss to ss+nn.
1014
1015         memmap=nn[KMG]$ss[KMG]
1016                         [KNL,ACPI] Mark specific memory as reserved.
1017                         Region of memory to be used, from ss to ss+nn.
1018
1019         meye.*=         [HW] Set MotionEye Camera parameters
1020                         See Documentation/video4linux/meye.txt.
1021
1022         mga=            [HW,DRM]
1023
1024         mousedev.tap_time=
1025                         [MOUSE] Maximum time between finger touching and
1026                         leaving touchpad surface for touch to be considered
1027                         a tap and be reported as a left button click (for
1028                         touchpads working in absolute mode only).
1029                         Format: <msecs>
1030         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
1031                         reporting absolute coordinates, such as tablets
1032         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
1033                         reporting absolute coordinates, such as tablets
1034
1035         mpu401=         [HW,OSS]
1036                         Format: <io>,<irq>
1037
1038         MTD_Partition=  [MTD]
1039                         Format: <name>,<region-number>,<size>,<offset>
1040
1041         MTD_Region=     [MTD] Format:
1042                         <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1043
1044         mtdparts=       [MTD]
1045                         See drivers/mtd/cmdline.c.
1046
1047         mtouchusb.raw_coordinates=
1048                         [HW] Make the MicroTouch USB driver use raw coordinates
1049                         ('y', default) or cooked coordinates ('n')
1050
1051         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
1052
1053         NCR_D700=       [HW,SCSI]
1054                         See header of drivers/scsi/NCR_D700.c.
1055
1056         ncr5380=        [HW,SCSI]
1057
1058         ncr53c400=      [HW,SCSI]
1059
1060         ncr53c400a=     [HW,SCSI]
1061
1062         ncr53c406a=     [HW,SCSI]
1063
1064         ncr53c8xx=      [HW,SCSI]
1065
1066         netdev=         [NET] Network devices parameters
1067                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1068                         Note that mem_start is often overloaded to mean
1069                         something different and driver-specific.
1070                         This usage is only documented in each driver source
1071                         file if at all.
1072
1073         nfsaddrs=       [NFS]
1074                         See Documentation/nfsroot.txt.
1075
1076         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
1077                         See Documentation/nfsroot.txt.
1078
1079         nfs.callback_tcpport=
1080                         [NFS] set the TCP port on which the NFSv4 callback
1081                         channel should listen.
1082
1083         nfs.idmap_cache_timeout=
1084                         [NFS] set the maximum lifetime for idmapper cache
1085                         entries.
1086
1087         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
1088
1089         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
1090                         emulation library even if a 387 maths coprocessor
1091                         is present.
1092
1093         noacpi          [LIBATA] Disables use of ACPI in libata suspend/resume
1094                         when set.
1095                         Format: <int>
1096
1097         noaliencache    [MM, NUMA, SLAB] Disables the allocation of alien
1098                         caches in the slab allocator.  Saves per-node memory,
1099                         but will impact performance.
1100
1101         noalign         [KNL,ARM]
1102
1103         noapic          [SMP,APIC] Tells the kernel to not make use of any
1104                         IOAPICs that may be present in the system.
1105
1106         noasync         [HW,M68K] Disables async and sync negotiation for
1107                         all devices.
1108
1109         nobats          [PPC] Do not use BATs for mapping kernel lowmem
1110                         on "Classic" PPC cores.
1111
1112         nocache         [ARM]
1113
1114         nodelayacct     [KNL] Disable per-task delay accounting
1115
1116         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
1117
1118         noexec          [IA-64]
1119
1120         noexec          [IA-32,X86-64]
1121                         noexec=on: enable non-executable mappings (default)
1122                         noexec=off: disable nn-executable mappings
1123
1124         nofxsr          [BUGS=IA-32] Disables x86 floating point extended
1125                         register save and restore. The kernel will only save
1126                         legacy floating-point registers on task switch.
1127
1128         nohlt           [BUGS=ARM]
1129
1130         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
1131                         instruction doesn't work correctly and not to
1132                         use it.
1133
1134         nohalt          [IA-64] Tells the kernel not to use the power saving
1135                         function PAL_HALT_LIGHT when idle. This increases
1136                         power-consumption. On the positive side, it reduces
1137                         interrupt wake-up latency, which may improve performance
1138                         in certain environments such as networked servers or
1139                         real-time systems.
1140
1141         nohz=           [KNL] Boottime enable/disable dynamic ticks
1142                         Valid arguments: on, off
1143                         Default: on
1144
1145         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
1146
1147         noirqdebug      [IA-32] Disables the code which attempts to detect and
1148                         disable unhandled interrupt sources.
1149
1150         no_timer_check  [IA-32,X86_64,APIC] Disables the code which tests for
1151                         broken timer IRQ sources.
1152
1153         noisapnp        [ISAPNP] Disables ISA PnP code.
1154
1155         noinitrd        [RAM] Tells the kernel not to load any configured
1156                         initial RAM disk.
1157
1158         nointroute      [IA-64]
1159
1160         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
1161
1162         nolapic_timer   [IA-32,APIC] Do not use the local APIC timer.
1163
1164         noltlbs         [PPC] Do not use large page/tlb entries for kernel
1165                         lowmem mapping on PPC40x.
1166
1167         nomca           [IA-64] Disable machine check abort handling
1168
1169         nomce           [IA-32] Machine Check Exception
1170
1171         noreplace-paravirt      [IA-32,PV_OPS] Don't patch paravirt_ops
1172
1173         noreplace-smp   [IA-32,SMP] Don't replace SMP instructions
1174                         with UP alternatives
1175
1176         noresidual      [PPC] Don't use residual data on PReP machines.
1177
1178         noresume        [SWSUSP] Disables resume and restores original swap
1179                         space.
1180
1181         no-scroll       [VGA] Disables scrollback.
1182                         This is required for the Braillex ib80-piezo Braille
1183                         reader made by F.H. Papenmeier (Germany).
1184
1185         nosbagart       [IA-64]
1186
1187         nosep           [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1188
1189         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
1190
1191         nosync          [HW,M68K] Disables sync negotiation for all devices.
1192
1193         notsc           [BUGS=IA-32] Disable Time Stamp Counter
1194
1195         nousb           [USB] Disable the USB subsystem
1196
1197         nowb            [ARM]
1198
1199         nr_uarts=       [SERIAL] maximum number of UARTs to be registered.
1200
1201         opl3=           [HW,OSS]
1202                         Format: <io>
1203
1204         opl3sa2=        [HW,OSS] Format:
1205                         <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1206
1207         oprofile.timer= [HW]
1208                         Use timer interrupt instead of performance counters
1209
1210         optcd=          [HW,CD]
1211                         Format: <io>
1212
1213         osst=           [HW,SCSI] SCSI Tape Driver
1214                         Format: <buffer_size>,<write_threshold>
1215                         See also Documentation/scsi/st.txt.
1216
1217         panic=          [KNL] Kernel behaviour on panic
1218                         Format: <timeout>
1219
1220         parkbd.port=    [HW] Parallel port number the keyboard adapter is
1221                         connected to, default is 0.
1222                         Format: <parport#>
1223         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
1224                         0 for XT, 1 for AT (default is AT).
1225                         Format: <mode>
1226
1227         parport=        [HW,PPT] Specify parallel ports. 0 disables.
1228                         Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1229                         Use 'auto' to force the driver to use any
1230                         IRQ/DMA settings detected (the default is to
1231                         ignore detected IRQ/DMA settings because of
1232                         possible conflicts). You can specify the base
1233                         address, IRQ, and DMA settings; IRQ and DMA
1234                         should be numbers, or 'auto' (for using detected
1235                         settings on that particular port), or 'nofifo'
1236                         (to avoid using a FIFO even if it is detected).
1237                         Parallel ports are assigned in the order they
1238                         are specified on the command line, starting
1239                         with parport0.
1240
1241         parport_init_mode=      [HW,PPT]
1242                         Configure VIA parallel port to operate in
1243                         a specific mode. This is necessary on Pegasos
1244                         computer where firmware has no options for setting
1245                         up parallel port mode and sets it to spp.
1246                         Currently this function knows 686a and 8231 chips.
1247                         Format: [spp|ps2|epp|ecp|ecpepp]
1248
1249         pas2=           [HW,OSS] Format:
1250                         <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1251
1252         pas16=          [HW,SCSI]
1253                         See header of drivers/scsi/pas16.c.
1254
1255         pause_on_oops=
1256                         Halt all CPUs after the first oops has been printed for
1257                         the specified number of seconds.  This is to be used if
1258                         your oopses keep scrolling off the screen.
1259
1260         pcbit=          [HW,ISDN]
1261
1262         pcd.            [PARIDE]
1263                         See header of drivers/block/paride/pcd.c.
1264                         See also Documentation/paride.txt.
1265
1266         pci=option[,option...]  [PCI] various PCI subsystem options:
1267                 off             [IA-32] don't probe for the PCI bus
1268                 bios            [IA-32] force use of PCI BIOS, don't access
1269                                 the hardware directly. Use this if your machine
1270                                 has a non-standard PCI host bridge.
1271                 nobios          [IA-32] disallow use of PCI BIOS, only direct
1272                                 hardware access methods are allowed. Use this
1273                                 if you experience crashes upon bootup and you
1274                                 suspect they are caused by the BIOS.
1275                 conf1           [IA-32] Force use of PCI Configuration
1276                                 Mechanism 1.
1277                 conf2           [IA-32] Force use of PCI Configuration
1278                                 Mechanism 2.
1279                 nommconf        [IA-32,X86_64] Disable use of MMCONFIG for PCI
1280                                 Configuration
1281                 nomsi           [MSI] If the PCI_MSI kernel config parameter is
1282                                 enabled, this kernel boot option can be used to
1283                                 disable the use of MSI interrupts system-wide.
1284                 nosort          [IA-32] Don't sort PCI devices according to
1285                                 order given by the PCI BIOS. This sorting is
1286                                 done to get a device order compatible with
1287                                 older kernels.
1288                 biosirq         [IA-32] Use PCI BIOS calls to get the interrupt
1289                                 routing table. These calls are known to be buggy
1290                                 on several machines and they hang the machine
1291                                 when used, but on other computers it's the only
1292                                 way to get the interrupt routing table. Try
1293                                 this option if the kernel is unable to allocate
1294                                 IRQs or discover secondary PCI buses on your
1295                                 motherboard.
1296                 rom             [IA-32] Assign address space to expansion ROMs.
1297                                 Use with caution as certain devices share
1298                                 address decoders between ROMs and other
1299                                 resources.
1300                 irqmask=0xMMMM  [IA-32] Set a bit mask of IRQs allowed to be
1301                                 assigned automatically to PCI devices. You can
1302                                 make the kernel exclude IRQs of your ISA cards
1303                                 this way.
1304                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1305                                 of the PIRQ table (normally generated
1306                                 by the BIOS) if it is outside the
1307                                 F0000h-100000h range.
1308                 lastbus=N       [IA-32] Scan all buses thru bus #N. Can be
1309                                 useful if the kernel is unable to find your
1310                                 secondary buses and you want to tell it
1311                                 explicitly which ones they are.
1312                 assign-busses   [IA-32] Always assign all PCI bus
1313                                 numbers ourselves, overriding
1314                                 whatever the firmware may have done.
1315                 usepirqmask     [IA-32] Honor the possible IRQ mask stored
1316                                 in the BIOS $PIR table. This is needed on
1317                                 some systems with broken BIOSes, notably
1318                                 some HP Pavilion N5400 and Omnibook XE3
1319                                 notebooks. This will have no effect if ACPI
1320                                 IRQ routing is enabled.
1321                 noacpi          [IA-32] Do not use ACPI for IRQ routing
1322                                 or for PCI scanning.
1323                 routeirq        Do IRQ routing for all PCI devices.
1324                                 This is normally done in pci_enable_device(),
1325                                 so this option is a temporary workaround
1326                                 for broken drivers that don't call it.
1327                 firmware        [ARM] Do not re-enumerate the bus but instead
1328                                 just use the configuration from the
1329                                 bootloader. This is currently used on
1330                                 IXP2000 systems where the bus has to be
1331                                 configured a certain way for adjunct CPUs.
1332                 noearly         [X86] Don't do any early type 1 scanning.
1333                                 This might help on some broken boards which
1334                                 machine check when some devices' config space
1335                                 is read. But various workarounds are disabled
1336                                 and some IOMMU drivers will not work.
1337                 bfsort          Sort PCI devices into breadth-first order.
1338                                 This sorting is done to get a device
1339                                 order compatible with older (<= 2.4) kernels.
1340                 nobfsort        Don't sort PCI devices into breadth-first order.
1341                 cbiosize=nn[KMG]        The fixed amount of bus space which is
1342                                 reserved for the CardBus bridge's IO window.
1343                                 The default value is 256 bytes.
1344                 cbmemsize=nn[KMG]       The fixed amount of bus space which is
1345                                 reserved for the CardBus bridge's memory
1346                                 window. The default value is 64 megabytes.
1347
1348         pcmv=           [HW,PCMCIA] BadgePAD 4
1349
1350         pd.             [PARIDE]
1351                         See Documentation/paride.txt.
1352
1353         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1354                         boot time.
1355                         Format: { 0 | 1 }
1356                         See arch/parisc/kernel/pdc_chassis.c
1357
1358         pf.             [PARIDE]
1359                         See Documentation/paride.txt.
1360
1361         pg.             [PARIDE]
1362                         See Documentation/paride.txt.
1363
1364         pirq=           [SMP,APIC] Manual mp-table setup
1365                         See Documentation/i386/IO-APIC.txt.
1366
1367         plip=           [PPT,NET] Parallel port network link
1368                         Format: { parport<nr> | timid | 0 }
1369                         See also Documentation/parport.txt.
1370
1371         pnpacpi=        [ACPI]
1372                         { off }
1373
1374         pnpbios=        [ISAPNP]
1375                         { on | off | curr | res | no-curr | no-res }
1376
1377         pnp_reserve_irq=
1378                         [ISAPNP] Exclude IRQs for the autoconfiguration
1379
1380         pnp_reserve_dma=
1381                         [ISAPNP] Exclude DMAs for the autoconfiguration
1382
1383         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1384                         Ranges are in pairs (I/O port base and size).
1385
1386         pnp_reserve_mem=
1387                         [ISAPNP] Exclude memory regions for the
1388                         autoconfiguration.
1389                         Ranges are in pairs (memory base and size).
1390
1391         profile=        [KNL] Enable kernel profiling via /proc/profile
1392                         Format: [schedule,]<number>
1393                         Param: "schedule" - profile schedule points.
1394                         Param: <number> - step/bucket size as a power of 2 for
1395                                 statistical time based profiling.
1396                         Param: "sleep" - profile D-state sleeping (millisecs)
1397
1398         processor.max_cstate=   [HW,ACPI]
1399                         Limit processor to maximum C-state
1400                         max_cstate=9 overrides any DMI blacklist limit.
1401
1402         processor.nocst [HW,ACPI]
1403                         Ignore the _CST method to determine C-states,
1404                         instead using the legacy FADT method
1405
1406         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1407                         before loading.
1408                         See Documentation/ramdisk.txt.
1409
1410         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1411                         probe for; one of (bare|imps|exps|lifebook|any).
1412         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1413                         per second.
1414         psmouse.resetafter=     [HW,MOUSE]
1415                         Try to reset the device after so many bad packets
1416                         (0 = never).
1417         psmouse.resolution=
1418                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1419         psmouse.smartscroll=
1420                         [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1421                         0 = disabled, 1 = enabled (default).
1422
1423         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1424                         Format:
1425                         <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1426
1427         pt.             [PARIDE]
1428                         See Documentation/paride.txt.
1429
1430         quiet           [KNL] Disable most log messages
1431
1432         r128=           [HW,DRM]
1433
1434         raid=           [HW,RAID]
1435                         See Documentation/md.txt.
1436
1437         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1438                         See Documentation/ramdisk.txt.
1439
1440         ramdisk_blocksize=      [RAM]
1441                         See Documentation/ramdisk.txt.
1442
1443         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1444                         New name for the ramdisk parameter.
1445                         See Documentation/ramdisk.txt.
1446
1447         rcu.blimit=     [KNL,BOOT] Set maximum number of finished
1448                         RCU callbacks to process in one batch.
1449
1450         rcu.qhimark=    [KNL,BOOT] Set threshold of queued
1451                         RCU callbacks over which batch limiting is disabled.
1452
1453         rcu.qlowmark=   [KNL,BOOT] Set threshold of queued
1454                         RCU callbacks below which batch limiting is re-enabled.
1455
1456         rdinit=         [KNL]
1457                         Format: <full_path>
1458                         Run specified binary instead of /init from the ramdisk,
1459                         used for early userspace startup. See initrd.
1460
1461         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1462                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1463                         See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1464
1465         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1466
1467         reservetop=     [IA-32]
1468                         Format: nn[KMG]
1469                         Reserves a hole at the top of the kernel virtual
1470                         address space.
1471
1472         reset_devices   [KNL] Force drivers to reset the underlying device
1473                         during initialization.
1474
1475         resume=         [SWSUSP]
1476                         Specify the partition device for software suspend
1477
1478         resume_offset=  [SWSUSP]
1479                         Specify the offset from the beginning of the partition
1480                         given by "resume=" at which the swap header is located,
1481                         in <PAGE_SIZE> units (needed only for swap files).
1482                         See  Documentation/power/swsusp-and-swap-files.txt
1483
1484         retain_initrd   [RAM] Keep initrd memory after extraction
1485
1486         rhash_entries=  [KNL,NET]
1487                         Set number of hash buckets for route cache
1488
1489         riscom8=        [HW,SERIAL]
1490                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1491
1492         ro              [KNL] Mount root device read-only on boot
1493
1494         root=           [KNL] Root filesystem
1495
1496         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1497                         mount the root filesystem
1498
1499         rootflags=      [KNL] Set root filesystem mount option string
1500
1501         rootfstype=     [KNL] Set root filesystem type
1502
1503         rw              [KNL] Mount root device read-write on boot
1504
1505         S               [KNL] Run init in single mode
1506
1507         sa1100ir        [NET]
1508                         See drivers/net/irda/sa1100_ir.c.
1509
1510         sb=             [HW,OSS]
1511                         Format: <io>,<irq>,<dma>,<dma2>
1512
1513         sbni=           [NET] Granch SBNI12 leased line adapter
1514
1515         sbpcd=          [HW,CD] Soundblaster CD adapter
1516                         Format: <io>,<type>
1517                         See a comment before function sbpcd_setup() in
1518                         drivers/cdrom/sbpcd.c.
1519
1520         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1521                         Format: <io>[,<timeout>[,<isapnp>]]
1522
1523         scsi_debug_*=   [SCSI]
1524                         See drivers/scsi/scsi_debug.c.
1525
1526         scsi_default_dev_flags=
1527                         [SCSI] SCSI default device flags
1528                         Format: <integer>
1529
1530         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1531                         Format: <vendor>:<model>:<flags>
1532                         (flags are integer value)
1533
1534         scsi_logging=   [SCSI]
1535
1536         scsi_mod.scan=  [SCSI] sync (default) scans SCSI busses as they are
1537                         discovered.  async scans them in kernel threads,
1538                         allowing boot to proceed.  none ignores them, expecting
1539                         user space to do the scan.
1540
1541         selinux         [SELINUX] Disable or enable SELinux at boot time.
1542                         Format: { "0" | "1" }
1543                         See security/selinux/Kconfig help text.
1544                         0 -- disable.
1545                         1 -- enable.
1546                         Default value is set via kernel config option.
1547                         If enabled at boot time, /selinux/disable can be used
1548                         later to disable prior to initial policy load.
1549
1550         selinux_compat_net =
1551                         [SELINUX] Set initial selinux_compat_net flag value.
1552                         Format: { "0" | "1" }
1553                         0 -- use new secmark-based packet controls
1554                         1 -- use legacy packet controls
1555                         Default value is 0 (preferred).
1556                         Value can be changed at runtime via
1557                         /selinux/compat_net.
1558
1559         serialnumber    [BUGS=IA-32]
1560
1561         sg_def_reserved_size=   [SCSI]
1562
1563         shapers=        [NET]
1564                         Maximal number of shapers.
1565
1566         sim710=         [SCSI,HW]
1567                         See header of drivers/scsi/sim710.c.
1568
1569         simeth=         [IA-64]
1570         simscsi=
1571
1572         sjcd=           [HW,CD]
1573                         Format: <io>,<irq>,<dma>
1574                         See header of drivers/cdrom/sjcd.c.
1575
1576         slram=          [HW,MTD]
1577
1578         slub_debug      [MM, SLUB]
1579                         Enabling slub_debug allows one to determine the culprit
1580                         if slab objects become corrupted. Enabling slub_debug
1581                         creates guard zones around objects and poisons objects
1582                         when not in use. Also tracks the last alloc / free.
1583                         For more information see Documentation/vm/slub.txt.
1584
1585         slub_max_order= [MM, SLUB]
1586                         Determines the maximum allowed order for slabs. Setting
1587                         this too high may cause fragmentation.
1588                         For more information see Documentation/vm/slub.txt.
1589
1590         slub_min_objects=       [MM, SLUB]
1591                         The minimum objects per slab. SLUB will increase the
1592                         slab order up to slub_max_order to generate a
1593                         sufficiently big slab to satisfy the number of objects.
1594                         The higher the number of objects the smaller the overhead
1595                         of tracking slabs.
1596                         For more information see Documentation/vm/slub.txt.
1597
1598         slub_min_order= [MM, SLUB]
1599                         Determines the mininum page order for slabs. Must be
1600                         lower than slub_max_order
1601                         For more information see Documentation/vm/slub.txt.
1602
1603         slub_nomerge    [MM, SLUB]
1604                         Disable merging of slabs of similar size. May be
1605                         necessary if there is some reason to distinguish
1606                         allocs to different slabs.
1607                         For more information see Documentation/vm/slub.txt.
1608
1609         smart2=         [HW]
1610                         Format: <io1>[,<io2>[,...,<io8>]]
1611
1612         smp-alt-once    [IA-32,SMP] On a hotplug CPU system, only
1613                         attempt to substitute SMP alternatives once at boot.
1614
1615         smsc-ircc2.nopnp        [HW] Don't use PNP to discover SMC devices
1616         smsc-ircc2.ircc_cfg=    [HW] Device configuration I/O port
1617         smsc-ircc2.ircc_sir=    [HW] SIR base I/O port
1618         smsc-ircc2.ircc_fir=    [HW] FIR base I/O port
1619         smsc-ircc2.ircc_irq=    [HW] IRQ line
1620         smsc-ircc2.ircc_dma=    [HW] DMA channel
1621         smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1622                                 0: Toshiba Satellite 1800 (GP data pin select)
1623                                 1: Fast pin select (default)
1624                                 2: ATC IRMode
1625
1626         snd-ad1816a=    [HW,ALSA]
1627
1628         snd-ad1848=     [HW,ALSA]
1629
1630         snd-ali5451=    [HW,ALSA]
1631
1632         snd-als100=     [HW,ALSA]
1633
1634         snd-als4000=    [HW,ALSA]
1635
1636         snd-azt2320=    [HW,ALSA]
1637
1638         snd-cmi8330=    [HW,ALSA]
1639
1640         snd-cmipci=     [HW,ALSA]
1641
1642         snd-cs4231=     [HW,ALSA]
1643
1644         snd-cs4232=     [HW,ALSA]
1645
1646         snd-cs4236=     [HW,ALSA]
1647
1648         snd-cs4281=     [HW,ALSA]
1649
1650         snd-cs46xx=     [HW,ALSA]
1651
1652         snd-dt019x=     [HW,ALSA]
1653
1654         snd-dummy=      [HW,ALSA]
1655
1656         snd-emu10k1=    [HW,ALSA]
1657
1658         snd-ens1370=    [HW,ALSA]
1659
1660         snd-ens1371=    [HW,ALSA]
1661
1662         snd-es968=      [HW,ALSA]
1663
1664         snd-es1688=     [HW,ALSA]
1665
1666         snd-es18xx=     [HW,ALSA]
1667
1668         snd-es1938=     [HW,ALSA]
1669
1670         snd-es1968=     [HW,ALSA]
1671
1672         snd-fm801=      [HW,ALSA]
1673
1674         snd-gusclassic= [HW,ALSA]
1675
1676         snd-gusextreme= [HW,ALSA]
1677
1678         snd-gusmax=     [HW,ALSA]
1679
1680         snd-hdsp=       [HW,ALSA]
1681
1682         snd-ice1712=    [HW,ALSA]
1683
1684         snd-intel8x0=   [HW,ALSA]
1685
1686         snd-interwave=  [HW,ALSA]
1687
1688         snd-interwave-stb=
1689                         [HW,ALSA]
1690
1691         snd-korg1212=   [HW,ALSA]
1692
1693         snd-maestro3=   [HW,ALSA]
1694
1695         snd-mpu401=     [HW,ALSA]
1696
1697         snd-mtpav=      [HW,ALSA]
1698
1699         snd-nm256=      [HW,ALSA]
1700
1701         snd-opl3sa2=    [HW,ALSA]
1702
1703         snd-opti92x-ad1848=
1704                         [HW,ALSA]
1705
1706         snd-opti92x-cs4231=
1707                         [HW,ALSA]
1708
1709         snd-opti93x=    [HW,ALSA]
1710
1711         snd-pmac=       [HW,ALSA]
1712
1713         snd-rme32=      [HW,ALSA]
1714
1715         snd-rme96=      [HW,ALSA]
1716
1717         snd-rme9652=    [HW,ALSA]
1718
1719         snd-sb8=        [HW,ALSA]
1720
1721         snd-sb16=       [HW,ALSA]
1722
1723         snd-sbawe=      [HW,ALSA]
1724
1725         snd-serial=     [HW,ALSA]
1726
1727         snd-sgalaxy=    [HW,ALSA]
1728
1729         snd-sonicvibes= [HW,ALSA]
1730
1731         snd-sun-amd7930=
1732                         [HW,ALSA]
1733
1734         snd-sun-cs4231= [HW,ALSA]
1735
1736         snd-trident=    [HW,ALSA]
1737
1738         snd-usb-audio=  [HW,ALSA,USB]
1739
1740         snd-via82xx=    [HW,ALSA]
1741
1742         snd-virmidi=    [HW,ALSA]
1743
1744         snd-wavefront=  [HW,ALSA]
1745
1746         snd-ymfpci=     [HW,ALSA]
1747
1748         sonycd535=      [HW,CD]
1749                         Format: <io>[,<irq>]
1750
1751         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1752                         See Documentation/sonypi.txt
1753
1754         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1755                         See Documentation/specialix.txt.
1756
1757         spia_io_base=   [HW,MTD]
1758         spia_fio_base=
1759         spia_pedr=
1760         spia_peddr=
1761
1762         sscape=         [HW,OSS]
1763                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1764
1765         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1766                         See Documentation/scsi/st.txt.
1767
1768         st0x=           [HW,SCSI]
1769                         See header of drivers/scsi/seagate.c.
1770
1771         sti=            [PARISC,HW]
1772                         Format: <num>
1773                         Set the STI (builtin display/keyboard on the HP-PARISC
1774                         machines) console (graphic card) which should be used
1775                         as the initial boot-console.
1776                         See also comment in drivers/video/console/sticore.c.
1777
1778         sti_font=       [HW]
1779                         See comment in drivers/video/console/sticore.c.
1780
1781         stifb=          [HW]
1782                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1783
1784         sunrpc.pool_mode=
1785                         [NFS]
1786                         Control how the NFS server code allocates CPUs to
1787                         service thread pools.  Depending on how many NICs
1788                         you have and where their interrupts are bound, this
1789                         option will affect which CPUs will do NFS serving.
1790                         Note: this parameter cannot be changed while the
1791                         NFS server is running.
1792
1793                         auto        the server chooses an appropriate mode
1794                                     automatically using heuristics
1795                         global      a single global pool contains all CPUs
1796                         percpu      one pool for each CPU
1797                         pernode     one pool for each NUMA node (equivalent
1798                                     to global on non-NUMA machines)
1799
1800         swiotlb=        [IA-64] Number of I/O TLB slabs
1801
1802         switches=       [HW,M68k]
1803
1804         sym53c416=      [HW,SCSI]
1805                         See header of drivers/scsi/sym53c416.c.
1806
1807         sysrq_always_enabled
1808                         [KNL]
1809                         Ignore sysrq setting - this boot parameter will
1810                         neutralize any effect of /proc/sys/kernel/sysrq.
1811                         Useful for debugging.
1812
1813         t128=           [HW,SCSI]
1814                         See header of drivers/scsi/t128.c.
1815
1816         tdfx=           [HW,DRM]
1817
1818         thash_entries=  [KNL,NET]
1819                         Set number of hash buckets for TCP connection
1820
1821         time            Show timing data prefixed to each printk message line
1822
1823         tipar.timeout=  [HW,PPT]
1824                         Set communications timeout in tenths of a second
1825                         (default 15).
1826
1827         tipar.delay=    [HW,PPT]
1828                         Set inter-bit delay in microseconds (default 10).
1829
1830         tmc8xx=         [HW,SCSI]
1831                         See header of drivers/scsi/seagate.c.
1832
1833         tmscsim=        [HW,SCSI]
1834                         See comment before function dc390_setup() in
1835                         drivers/scsi/tmscsim.c.
1836
1837         tp720=          [HW,PS2]
1838
1839         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1840                         Format:
1841                         <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1842
1843         tsdev.xres=     [TS] Horizontal screen resolution.
1844         tsdev.yres=     [TS] Vertical screen resolution.
1845
1846         turbografx.map[2|3]=    [HW,JOY]
1847                         TurboGraFX parallel port interface
1848                         Format:
1849                         <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1850                         See also Documentation/input/joystick-parport.txt
1851
1852         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1853                         See header of drivers/scsi/u14-34f.c.
1854
1855         uart401=        [HW,OSS]
1856                         Format: <io>,<irq>
1857
1858         uart6850=       [HW,OSS]
1859                         Format: <io>,<irq>
1860
1861         uhci-hcd.ignore_oc=
1862                         [USB] Ignore overcurrent events (default N).
1863                         Some badly-designed motherboards generate lots of
1864                         bogus events, for ports that aren't wired to
1865                         anything.  Set this parameter to avoid log spamming.
1866                         Note that genuine overcurrent events won't be
1867                         reported either.
1868
1869         usbcore.autosuspend=
1870                         [USB] The autosuspend time delay (in seconds) used
1871                         for newly-detected USB devices (default 2).  This
1872                         is the time required before an idle device will be
1873                         autosuspended.  Devices for which the delay is set
1874                         to a negative value won't be autosuspended at all.
1875
1876         usbhid.mousepoll=
1877                         [USBHID] The interval which mice are to be polled at.
1878
1879         vdso=           [IA-32,SH]
1880                         vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1881                         vdso=1: enable VDSO (default)
1882                         vdso=0: disable VDSO mapping
1883
1884         video=          [FB] Frame buffer configuration
1885                         See Documentation/fb/modedb.txt.
1886
1887         vga=            [BOOT,IA-32] Select a particular video mode
1888                         See Documentation/i386/boot.txt and
1889                         Documentation/svga.txt.
1890                         Use vga=ask for menu.
1891                         This is actually a boot loader parameter; the value is
1892                         passed to the kernel using a special protocol.
1893
1894         vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1895                         size of <nn>. This can be used to increase the
1896                         minimum size (128MB on x86). It can also be used to
1897                         decrease the size and leave more room for directly
1898                         mapped kernel RAM.
1899
1900         vmhalt=         [KNL,S390] Perform z/VM CP command after system halt.
1901                         Format: <command>
1902
1903         vmpanic=        [KNL,S390] Perform z/VM CP command after kernel panic.
1904                         Format: <command>
1905
1906         vmpoff=         [KNL,S390] Perform z/VM CP command after power off.
1907                         Format: <command>
1908
1909         waveartist=     [HW,OSS]
1910                         Format: <io>,<irq>,<dma>,<dma2>
1911
1912         wd33c93=        [HW,SCSI]
1913                         See header of drivers/scsi/wd33c93.c.
1914
1915         wd7000=         [HW,SCSI]
1916                         See header of drivers/scsi/wd7000.c.
1917
1918         wdt=            [WDT] Watchdog
1919                         See Documentation/watchdog/watchdog.txt.
1920
1921         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1922         xd_geo=         See header of drivers/block/xd.c.
1923
1924         xirc2ps_cs=     [NET,PCMCIA]
1925                         Format:
1926                         <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1927
1928         norandmaps      Don't use address space randomization
1929                         Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1930
1931         unwind_debug=N  N > 0 will enable dwarf2 unwinder debugging
1932                         This is useful to get more information why
1933                         you got a "dwarf2 unwinder stuck"
1934
1935 ______________________________________________________________________
1936
1937 TODO:
1938
1939         Add documentation for ALSA options.
1940         Add more DRM drivers.