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         PARIDE  The ParIDE subsystem is enabled.
  68         PARISC  The PA-RISC architecture is enabled.
  69         PCI     PCI bus support is enabled.
  70         PCMCIA  The PCMCIA subsystem is enabled.
  71         PNP     Plug & Play support is enabled.
  72         PPC     PowerPC architecture is enabled.
  73         PPT     Parallel port support is enabled.
  74         PS2     Appropriate PS/2 support is enabled.
  75         RAM     RAM disk support is enabled.
  76         S390    S390 architecture is enabled.
  77         SCSI    Appropriate SCSI support is enabled.
  78                         A lot of drivers has their options described inside of
  79                         Documentation/scsi/.
  80         SELINUX SELinux support is enabled.
  81         SERIAL  Serial support is enabled.
  82         SH      SuperH architecture is enabled.
  83         SMP     The kernel is an SMP kernel.
  84         SPARC   Sparc architecture is enabled.
  85         SWSUSP  Software suspend is enabled.
  86         TS      Appropriate touchscreen support is enabled.
  87         USB     USB support is enabled.
  88         USBHID  USB Human Interface Device support is enabled.
  89         V4L     Video For Linux support is enabled.
  90         VGA     The VGA console has been enabled.
  91         VT      Virtual terminal support is enabled.
  92         WDT     Watchdog support is enabled.
  93         XT      IBM PC/XT MFM hard disk support is enabled.
  94         X86-64  X86-64 architecture is enabled.
  95                         More X86-64 boot options can be found in
  96                         Documentation/x86_64/boot-options.txt .
  97
  98 In addition, the following text indicates that the option:
  99
 100         BUGS=   Relates to possible processor bugs on the said processor.
 101         KNL     Is a kernel start-up parameter.
 102         BOOT    Is a boot loader parameter.
 103
 104 Parameters denoted with BOOT are actually interpreted by the boot
 105 loader, and have no meaning to the kernel directly.
 106 Do not modify the syntax of boot loader parameters without extreme
 107 need or coordination with <Documentation/i386/boot.txt>.
 108
 109 There are also arch-specific kernel-parameters not documented here.
 110 See for example <Documentation/x86_64/boot-options.txt>.
 111
 112 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
 113 a trailing = on the name of any parameter states that that parameter will
 114 be entered as an environment variable, whereas its absence indicates that
 115 it will appear as a kernel argument readable via /proc/cmdline by programs
 116 running once the system is up.
 117
 118 The number of kernel parameters is not limited, but the length of the
 119 complete command line (parameters including spaces etc.) is limited to
 120 a fixed number of characters. This limit depends on the architecture
 121 and is between 256 and 4096 characters. It is defined in the file
 122 ./include/asm/setup.h as COMMAND_LINE_SIZE.
 123
 124
 125         53c7xx=         [HW,SCSI] Amiga SCSI controllers
 126                         See header of drivers/scsi/53c7xx.c.
 127                         See also Documentation/scsi/ncr53c7xx.txt.
 128
 129         acpi=           [HW,ACPI,X86-64,i386]
 130                         Advanced Configuration and Power Interface
 131                         Format: { force | off | ht | strict | noirq }
 132                         force -- enable ACPI if default was off
 133                         off -- disable ACPI if default was on
 134                         noirq -- do not use ACPI for IRQ routing
 135                         ht -- run only enough ACPI to enable Hyper Threading
 136                         strict -- Be less tolerant of platforms that are not
 137                                 strictly ACPI specification compliant.
 138
 139                         See also Documentation/pm.txt, pci=noacpi
 140
 141         acpi_apic_instance=     [ACPI, IOAPIC]
 142                         Format: <int>
 143                         2: use 2nd APIC table, if available
 144                         1,0: use 1st APIC table
 145                         default: 2
 146
 147         acpi_sleep=     [HW,ACPI] Sleep options
 148                         Format: { s3_bios, s3_mode }
 149                         See Documentation/power/video.txt
 150
 151         acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 152                         Format: { level | edge | high | low }
 153
 154         acpi_irq_balance [HW,ACPI]
 155                         ACPI will balance active IRQs
 156                         default in APIC mode
 157
 158         acpi_irq_nobalance [HW,ACPI]
 159                         ACPI will not move active IRQs (default)
 160                         default in PIC mode
 161
 162         acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
 163                         use by PCI
 164                         Format: <irq>,<irq>...
 165
 166         acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
 167                         Format: <irq>,<irq>...
 168
 169         acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
 170                         Format: To spoof as Windows 98: ="Microsoft Windows"
 171
 172         acpi_osi=       [HW,ACPI] empty param disables _OSI
 173
 174         acpi_serialize  [HW,ACPI] force serialization of AML methods
 175
 176         acpi_skip_timer_override [HW,ACPI]
 177                         Recognize and ignore IRQ0/pin2 Interrupt Override.
 178                         For broken nForce2 BIOS resulting in XT-PIC timer.
 179         acpi_use_timer_override [HW,ACPI}
 180                         Use timer override. For some broken Nvidia NF5 boards
 181                         that require a timer override, but don't have
 182                         HPET
 183
 184         acpi_dbg_layer= [HW,ACPI]
 185                         Format: <int>
 186                         Each bit of the <int> indicates an ACPI debug layer,
 187                         1: enable, 0: disable. It is useful for boot time
 188                         debugging. After system has booted up, it can be set
 189                         via /proc/acpi/debug_layer.
 190
 191         acpi_dbg_level= [HW,ACPI]
 192                         Format: <int>
 193                         Each bit of the <int> indicates an ACPI debug level,
 194                         1: enable, 0: disable. It is useful for boot time
 195                         debugging. After system has booted up, it can be set
 196                         via /proc/acpi/debug_level.
 197
 198         acpi_fake_ecdt  [HW,ACPI] Workaround failure due to BIOS lacking ECDT
 199
 200         acpi_generic_hotkey [HW,ACPI]
 201                         Allow consolidated generic hotkey driver to
 202                         override platform specific driver.
 203                         See also Documentation/acpi-hotkey.txt.
 204
 205         acpi_pm_good    [IA-32,X86-64]
 206                         Override the pmtimer bug detection: force the kernel
 207                         to assume that this machine's pmtimer latches its value
 208                         and always returns good values.
 209
 210         enable_timer_pin_1 [i386,x86-64]
 211                         Enable PIN 1 of APIC timer
 212                         Can be useful to work around chipset bugs
 213                         (in particular on some ATI chipsets).
 214                         The kernel tries to set a reasonable default.
 215
 216         disable_timer_pin_1 [i386,x86-64]
 217                         Disable PIN 1 of APIC timer
 218                         Can be useful to work around chipset bugs.
 219
 220         ad1816=         [HW,OSS]
 221                         Format: <io>,<irq>,<dma>,<dma2>
 222                         See also Documentation/sound/oss/AD1816.
 223
 224         ad1848=         [HW,OSS]
 225                         Format: <io>,<irq>,<dma>,<dma2>,<type>
 226
 227         adlib=          [HW,OSS]
 228                         Format: <io>
 229
 230         advansys=       [HW,SCSI]
 231                         See header of drivers/scsi/advansys.c.
 232
 233         advwdt=         [HW,WDT] Advantech WDT
 234                         Format: <iostart>,<iostop>
 235
 236         aedsp16=        [HW,OSS] Audio Excel DSP 16
 237                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 238                         See also header of sound/oss/aedsp16.c.
 239
 240         aha152x=        [HW,SCSI]
 241                         See Documentation/scsi/aha152x.txt.
 242
 243         aha1542=        [HW,SCSI]
 244                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 245
 246         aic7xxx=        [HW,SCSI]
 247                         See Documentation/scsi/aic7xxx.txt.
 248
 249         aic79xx=        [HW,SCSI]
 250                         See Documentation/scsi/aic79xx.txt.
 251
 252         amijoy.map=     [HW,JOY] Amiga joystick support
 253                         Map of devices attached to JOY0DAT and JOY1DAT
 254                         Format: <a>,<b>
 255                         See also Documentation/kernel/input/joystick.txt
 256
 257         analog.map=     [HW,JOY] Analog joystick and gamepad support
 258                         Specifies type or capabilities of an analog joystick
 259                         connected to one of 16 gameports
 260                         Format: <type1>,<type2>,..<type16>
 261
 262         apc=            [HW,SPARC]
 263                         Power management functions (SPARCstation-4/5 + deriv.)
 264                         Format: noidle
 265                         Disable APC CPU standby support. SPARCstation-Fox does
 266                         not play well with APC CPU idle - disable it if you have
 267                         APC and your system crashes randomly.
 268
 269         apic=           [APIC,i386] Change the output verbosity whilst booting
 270                         Format: { quiet (default) | verbose | debug }
 271                         Change the amount of debugging information output
 272                         when initialising the APIC and IO-APIC components.
 273
 274         apm=            [APM] Advanced Power Management
 275                         See header of arch/i386/kernel/apm.c.
 276
 277         applicom=       [HW]
 278                         Format: <mem>,<irq>
 279
 280         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 281                         Format: <io>,<irq>,<nodeID>
 282
 283         ataflop=        [HW,M68k]
 284
 285         atarimouse=     [HW,MOUSE] Atari Mouse
 286
 287         atascsi=        [HW,SCSI] Atari SCSI
 288
 289         atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 290                         EzKey and similar keyboards
 291
 292         atkbd.reset=    [HW] Reset keyboard during initialization
 293
 294         atkbd.set=      [HW] Select keyboard code set
 295                         Format: <int> (2 = AT (default), 3 = PS/2)
 296
 297         atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 298                         keyboards
 299
 300         atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 301                         Format: <bool> (0 = real, 1 = synthetic (default))
 302
 303         atkbd.softrepeat= [HW]
 304                         Use software keyboard repeat
 305
 306         autotest        [IA64]
 307
 308         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 309                         Format: <io>,0x79 (?)
 310
 311         baycom_epp=     [HW,AX25]
 312                         Format: <io>,<mode>
 313
 314         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 315                         Format: <io>,<mode>
 316                         See header of drivers/net/hamradio/baycom_par.c.
 317
 318         baycom_ser_fdx= [HW,AX25]
 319                         BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 320                         Format: <io>,<irq>,<mode>[,<baud>]
 321                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 322
 323         baycom_ser_hdx= [HW,AX25]
 324                         BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 325                         Format: <io>,<irq>,<mode>
 326                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 327
 328         blkmtd_device=  [HW,MTD]
 329         blkmtd_erasesz=
 330         blkmtd_ro=
 331         blkmtd_bs=
 332         blkmtd_count=
 333
 334         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 335         bttv.radio=     Most important insmod options are available as
 336                         kernel args too.
 337         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 338         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 339
 340         BusLogic=       [HW,SCSI]
 341                         See drivers/scsi/BusLogic.c, comment before function
 342                         BusLogic_ParseDriverOptions().
 343
 344         c101=           [NET] Moxa C101 synchronous serial card
 345
 346         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 347                         Sometimes CPU hardware bugs make them report the cache
 348                         size incorrectly. The kernel will attempt work arounds
 349                         to fix known problems, but for some CPUs it is not
 350                         possible to determine what the correct size should be.
 351                         This option provides an override for these situations.
 352
 353         cdu31a=         [HW,CD]
 354                         Format: <io>,<irq>[,PAS]
 355                         See header of drivers/cdrom/cdu31a.c.
 356
 357         chandev=        [HW,NET] Generic channel device initialisation
 358
 359         checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 360                         Format: { "0" | "1" }
 361                         See security/selinux/Kconfig help text.
 362                         0 -- check protection applied by kernel (includes
 363                                 any implied execute protection).
 364                         1 -- check protection requested by application.
 365                         Default value is set via a kernel config option.
 366                         Value can be changed at runtime via
 367                                 /selinux/checkreqprot.
 368
 369         clock=          [BUGS=IA-32, HW] gettimeofday clocksource override.
 370                         [Deprecated]
 371                         Forces specified clocksource (if available) to be used
 372                         when calculating gettimeofday(). If specified
 373                         clocksource is not available, it defaults to PIT.
 374                         Format: { pit | tsc | cyclone | pmtmr }
 375
 376         code_bytes      [IA32] How many bytes of object code to print in an
 377                         oops report.
 378                         Range: 0 - 8192
 379                         Default: 64
 380
 381         disable_8254_timer
 382         enable_8254_timer
 383                         [IA32/X86_64] Disable/Enable interrupt 0 timer routing
 384                         over the 8254 in addition to over the IO-APIC. The
 385                         kernel tries to set a sensible default.
 386
 387         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
 388                         Format: disable
 389
 390         cm206=          [HW,CD]
 391                         Format: { auto | [<io>,][<irq>] }
 392
 393         com20020=       [HW,NET] ARCnet - COM20020 chipset
 394                         Format:
 395                         <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 396
 397         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 398                         Format: <io>[,<irq>]
 399
 400         com90xx=        [HW,NET]
 401                         ARCnet - COM90xx chipset (memory-mapped buffers)
 402                         Format: <io>[,<irq>[,<memstart>]]
 403
 404         condev=         [HW,S390] console device
 405         conmode=
 406
 407         console=        [KNL] Output console device and options.
 408
 409                 tty<n>  Use the virtual console device <n>.
 410
 411                 ttyS<n>[,options]
 412                 ttyUSB0[,options]
 413                         Use the specified serial port.  The options are of
 414                         the form "bbbbpnf", where "bbbb" is the baud rate,
 415                         "p" is parity ("n", "o", or "e"), "n" is number of
 416                         bits, and "f" is flow control ("r" for RTS or
 417                         omit it).  Default is "9600n8".
 418
 419                         See Documentation/serial-console.txt for more
 420                         information.  See
 421                         Documentation/networking/netconsole.txt for an
 422                         alternative.
 423
 424                 uart,io,<addr>[,options]
 425                 uart,mmio,<addr>[,options]
 426                         Start an early, polled-mode console on the 8250/16550
 427                         UART at the specified I/O port or MMIO address,
 428                         switching to the matching ttyS device later.  The
 429                         options are the same as for ttyS, above.
 430
 431         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 432                         Format:
 433                         <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 434
 435         cpia_pp=        [HW,PPT]
 436                         Format: { parport<nr> | auto | none }
 437
 438         crashkernel=nn[KMG]@ss[KMG]
 439                         [KNL] Reserve a chunk of physical memory to
 440                         hold a kernel to switch to with kexec on panic.
 441
 442         cs4232=         [HW,OSS]
 443                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 444
 445         cs89x0_dma=     [HW,NET]
 446                         Format: <dma>
 447
 448         cs89x0_media=   [HW,NET]
 449                         Format: { rj45 | aui | bnc }
 450
 451         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 452
 453         dasd=           [HW,NET]
 454                         See header of drivers/s390/block/dasd_devmap.c.
 455
 456         db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 457                         (one device per port)
 458                         Format: <port#>,<type>
 459                         See also Documentation/input/joystick-parport.txt
 460
 461         debug           [KNL] Enable kernel debugging (events log level).
 462
 463         debug_locks_verbose=
 464                         [KNL] verbose self-tests
 465                         Format=<0|1>
 466                         Print debugging info while doing the locking API
 467                         self-tests.
 468                         We default to 0 (no extra messages), setting it to
 469                         1 will print _a lot_ more information - normally
 470                         only useful to kernel developers.
 471
 472         decnet=         [HW,NET]
 473                         Format: <area>[,<node>]
 474                         See also Documentation/networking/decnet.txt.
 475
 476         dhash_entries=  [KNL]
 477                         Set number of hash buckets for dentry cache.
 478
 479         digi=           [HW,SERIAL]
 480                         IO parameters + enable/disable command.
 481
 482         digiepca=       [HW,SERIAL]
 483                         See drivers/char/README.epca and
 484                         Documentation/digiepca.txt.
 485
 486         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 487                         support available.
 488                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 489
 490         dmasound=       [HW,OSS] Sound subsystem buffers
 491
 492         dscc4.setup=    [NET]
 493
 494         dtc3181e=       [HW,SCSI]
 495
 496         earlyprintk=    [IA-32,X86-64,SH]
 497                         earlyprintk=vga
 498                         earlyprintk=serial[,ttySn[,baudrate]]
 499
 500                         Append ",keep" to not disable it when the real console
 501                         takes over.
 502
 503                         Only vga or serial at a time, not both.
 504
 505                         Currently only ttyS0 and ttyS1 are supported.
 506
 507                         Interaction with the standard serial driver is not
 508                         very good.
 509
 510                         The VGA output is eventually overwritten by the real
 511                         console.
 512
 513         eata=           [HW,SCSI]
 514
 515         ec_intr=        [HW,ACPI] ACPI Embedded Controller interrupt mode
 516                         Format: <int>
 517                         0: polling mode
 518                         non-0: interrupt mode (default)
 519
 520         eda=            [HW,PS2]
 521
 522         edb=            [HW,PS2]
 523
 524         edd=            [EDD]
 525                         Format: {"of[f]" | "sk[ipmbr]"}
 526                         See comment in arch/i386/boot/edd.S
 527
 528         eicon=          [HW,ISDN]
 529                         Format: <id>,<membase>,<irq>
 530
 531         eisa_irq_edge=  [PARISC,HW]
 532                         See header of drivers/parisc/eisa.c.
 533
 534         elanfreq=       [IA-32]
 535                         See comment before function elanfreq_setup() in
 536                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 537
 538         elevator=       [IOSCHED]
 539                         Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
 540                         See Documentation/block/as-iosched.txt and
 541                         Documentation/block/deadline-iosched.txt for details.
 542
 543         elfcorehdr=     [IA-32, X86_64]
 544                         Specifies physical address of start of kernel core
 545                         image elf header. Generally kexec loader will
 546                         pass this option to capture kernel.
 547                         See Documentation/kdump/kdump.txt for details.
 548
 549         enforcing       [SELINUX] Set initial enforcing status.
 550                         Format: {"0" | "1"}
 551                         See security/selinux/Kconfig help text.
 552                         0 -- permissive (log only, no denials).
 553                         1 -- enforcing (deny and log).
 554                         Default value is 0.
 555                         Value can be changed at runtime via /selinux/enforce.
 556
 557         es1371=         [HW,OSS]
 558                         Format: <spdif>,[<nomix>,[<amplifier>]]
 559                         See also header of sound/oss/es1371.c.
 560
 561         ether=          [HW,NET] Ethernet cards parameters
 562                         This option is obsoleted by the "netdev=" option, which
 563                         has equivalent usage. See its documentation for details.
 564
 565         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 566                         Format: <io>[,<irq>]
 567
 568         failslab=
 569         fail_page_alloc=
 570         fail_make_request=[KNL]
 571                         General fault injection mechanism.
 572                         Format: <interval>,<probability>,<space>,<times>
 573                         See also /Documentation/fault-injection/.
 574
 575         fd_mcs=         [HW,SCSI]
 576                         See header of drivers/scsi/fd_mcs.c.
 577
 578         fdomain=        [HW,SCSI]
 579                         See header of drivers/scsi/fdomain.c.
 580
 581         floppy=         [HW]
 582                         See Documentation/floppy.txt.
 583
 584         gamecon.map[2|3]=
 585                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 586                         support via parallel port (up to 5 devices per port)
 587                         Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 588                         See also Documentation/input/joystick-parport.txt
 589
 590         gamma=          [HW,DRM]
 591
 592         gdth=           [HW,SCSI]
 593                         See header of drivers/scsi/gdth.c.
 594
 595         gpt             [EFI] Forces disk with valid GPT signature but
 596                         invalid Protective MBR to be treated as GPT.
 597
 598         gscd=           [HW,CD]
 599                         Format: <io>
 600
 601         gvp11=          [HW,SCSI]
 602
 603         hashdist=       [KNL,NUMA] Large hashes allocated during boot
 604                         are distributed across NUMA nodes.  Defaults on
 605                         for IA-64, off otherwise.
 606                         Format: 0 | 1 (for off | on)
 607
 608         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 609
 610         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 611                         Format: <cyl>,<head>,<sect>
 612
 613         hd?=            [HW] (E)IDE subsystem
 614         hd?lun=         See Documentation/ide.txt.
 615
 616         highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 617                         size of <nn>. This works even on boxes that have no
 618                         highmem otherwise. This also works to reduce highmem
 619                         size on bigger boxes.
 620
 621         highres=        [KNL] Enable/disable high resolution timer mode.
 622                         Valid parameters: "on", "off"
 623                         Default: "on"
 624
 625         hisax=          [HW,ISDN]
 626                         See Documentation/isdn/README.HiSax.
 627
 628         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 629
 630         i8042.direct    [HW] Put keyboard port into non-translated mode
 631         i8042.dumbkbd   [HW] Pretend that controller can only read data from
 632                              keyboard and cannot control its state
 633                              (Don't attempt to blink the leds)
 634         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 635         i8042.nokbd     [HW] Don't check/create keyboard port
 636         i8042.nomux     [HW] Don't check presence of an active multiplexing
 637                              controller
 638         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 639                              controllers
 640         i8042.panicblink=
 641                         [HW] Frequency with which keyboard LEDs should blink
 642                              when kernel panics (default is 0.5 sec)
 643         i8042.reset     [HW] Reset the controller during init and cleanup
 644         i8042.unlock    [HW] Unlock (ignore) the keylock
 645
 646         i810=           [HW,DRM]
 647
 648         i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 649                         indicates that the driver is running on unsupported
 650                         hardware.
 651         i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 652                         does not match list of supported models.
 653         i8k.power_status
 654                         [HW] Report power status in /proc/i8k
 655                         (disabled by default)
 656         i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 657                         capability is set.
 658
 659         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 660                         See Documentation/mca.txt.
 661
 662         icn=            [HW,ISDN]
 663                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 664
 665         ide=            [HW] (E)IDE subsystem
 666                         Format: ide=nodma or ide=doubler or ide=reverse
 667                         See Documentation/ide.txt.
 668
 669         ide?=           [HW] (E)IDE subsystem
 670                         Format: ide?=noprobe or chipset specific parameters.
 671                         See Documentation/ide.txt.
 672
 673         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 674                         See Documentation/ide.txt.
 675
 676         idle=           [HW]
 677                         Format: idle=poll or idle=halt
 678
 679         ignore_loglevel [KNL]
 680                         Ignore loglevel setting - this will print /all/
 681                         kernel messages to the console. Useful for debugging.
 682
 683         ihash_entries=  [KNL]
 684                         Set number of hash buckets for inode cache.
 685
 686         in2000=         [HW,SCSI]
 687                         See header of drivers/scsi/in2000.c.
 688
 689         init=           [KNL]
 690                         Format: <full_path>
 691                         Run specified binary instead of /sbin/init as init
 692                         process.
 693
 694         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 695                         for working out where the kernel is dying during
 696                         startup.
 697
 698         initrd=         [BOOT] Specify the location of the initial ramdisk
 699
 700         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 701                         Format: <irq>
 702
 703         combined_mode=  [HW] control which driver uses IDE ports in combined
 704                         mode: legacy IDE driver, libata, or both
 705                         (in the libata case, libata.atapi_enabled=1 may be
 706                         useful as well).  Note that using the ide or libata
 707                         options may affect your device naming (e.g. by
 708                         changing hdc to sdb).
 709                         Format: combined (default), ide, or libata
 710
 711         inttest=        [IA64]
 712
 713         io7=            [HW] IO7 for Marvel based alpha systems
 714                         See comment before marvel_specify_io7 in
 715                         arch/alpha/kernel/core_marvel.c.
 716
 717         ip=             [IP_PNP]
 718                         See Documentation/nfsroot.txt.
 719
 720         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 721                         See comment before ip2_setup() in drivers/char/ip2.c.
 722
 723         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 724                         See header of drivers/scsi/ips.c.
 725
 726         ports=          [IP_VS_FTP] IPVS ftp helper module
 727                         Default is 21.
 728                         Up to 8 (IP_VS_APP_MAX_PORTS) ports
 729                         may be specified.
 730                         Format: <port>,<port>....
 731
 732         irqfixup        [HW]
 733                         When an interrupt is not handled search all handlers
 734                         for it. Intended to get systems with badly broken
 735                         firmware running.
 736
 737         irqpoll         [HW]
 738                         When an interrupt is not handled search all handlers
 739                         for it. Also check all handlers each timer
 740                         interrupt. Intended to get systems with badly broken
 741                         firmware running.
 742
 743         isapnp=         [ISAPNP]
 744                         Format: <RDP>,<reset>,<pci_scan>,<verbosity>
 745
 746         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 747                         Format:
 748                         <cpu number>,...,<cpu number>
 749                         or
 750                         <cpu number>-<cpu number>  (must be a positive range in ascending order)
 751                         or a mixture
 752                         <cpu number>,...,<cpu number>-<cpu number>
 753                         This option can be used to specify one or more CPUs
 754                         to isolate from the general SMP balancing and scheduling
 755                         algorithms. The only way to move a process onto or off
 756                         an "isolated" CPU is via the CPU affinity syscalls.
 757                         <cpu number> begins at 0 and the maximum value is
 758                         "number of CPUs in system - 1".
 759
 760                         This option is the preferred way to isolate CPUs. The
 761                         alternative -- manually setting the CPU mask of all
 762                         tasks in the system -- can cause problems and
 763                         suboptimal load balancer performance.
 764
 765         isp16=          [HW,CD]
 766                         Format: <io>,<irq>,<dma>,<setup>
 767
 768         iucv=           [HW,NET]
 769
 770         js=             [HW,JOY] Analog joystick
 771                         See Documentation/input/joystick.txt.
 772
 773         keepinitrd      [HW,ARM]
 774
 775         kstack=N        [IA-32,X86-64] Print N words from the kernel stack
 776                         in oops dumps.
 777
 778         l2cr=           [PPC]
 779
 780         lapic           [IA-32,APIC] Enable the local APIC even if BIOS
 781                         disabled it.
 782
 783         lapic_timer_c2_ok       [IA-32,x86-64,APIC] trust the local apic timer in
 784                         C2 power state.
 785
 786         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 787                         Format: addr:<io>,irq:<irq>
 788
 789         llsc*=          [IA64] See function print_params() in
 790                         arch/ia64/sn/kernel/llsc4.c.
 791
 792         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 793                         See Documentation/ramdisk.txt.
 794
 795         lockd.nlm_grace_period=P  [NFS] Assign grace period.
 796                         Format: <integer>
 797
 798         lockd.nlm_tcpport=N     [NFS] Assign TCP port.
 799                         Format: <integer>
 800
 801         lockd.nlm_timeout=T     [NFS] Assign timeout value.
 802                         Format: <integer>
 803
 804         lockd.nlm_udpport=M     [NFS] Assign UDP port.
 805                         Format: <integer>
 806
 807         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 808                         Format: <irq>
 809
 810         loglevel=       All Kernel Messages with a loglevel smaller than the
 811                         console loglevel will be printed to the console. It can
 812                         also be changed with klogd or other programs. The
 813                         loglevels are defined as follows:
 814
 815                         0 (KERN_EMERG)          system is unusable
 816                         1 (KERN_ALERT)          action must be taken immediately
 817                         2 (KERN_CRIT)           critical conditions
 818                         3 (KERN_ERR)            error conditions
 819                         4 (KERN_WARNING)        warning conditions
 820                         5 (KERN_NOTICE)         normal but significant condition
 821                         6 (KERN_INFO)           informational
 822                         7 (KERN_DEBUG)          debug-level messages
 823
 824         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 825                         Format: { n | nk | nM }
 826                         n must be a power of two.  The default size
 827                         is set in the kernel config file.
 828
 829         lp=0            [LP]    Specify parallel ports to use, e.g,
 830         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 831         lp=reset                first parallel port). 'lp=0' disables the
 832         lp=auto                 printer driver. 'lp=reset' (which can be
 833                                 specified in addition to the ports) causes
 834                                 attached printers to be reset. Using
 835                                 lp=port1,port2,... specifies the parallel ports
 836                                 to associate lp devices with, starting with
 837                                 lp0. A port specification may be 'none' to skip
 838                                 that lp device, or a parport name such as
 839                                 'parport0'. Specifying 'lp=auto' instead of a
 840                                 port specification list means that device IDs
 841                                 from each port should be examined, to see if
 842                                 an IEEE 1284-compliant printer is attached; if
 843                                 so, the driver will manage that printer.
 844                                 See also header of drivers/char/lp.c.
 845
 846         lpj=n           [KNL]
 847                         Sets loops_per_jiffy to given constant, thus avoiding
 848                         time-consuming boot-time autodetection (up to 250 ms per
 849                         CPU). 0 enables autodetection (default). To determine
 850                         the correct value for your kernel, boot with normal
 851                         autodetection and see what value is printed. Note that
 852                         on SMP systems the preset will be applied to all CPUs,
 853                         which is likely to cause problems if your CPUs need
 854                         significantly divergent settings. An incorrect value
 855                         will cause delays in the kernel to be wrong, leading to
 856                         unpredictable I/O errors and other breakage. Although
 857                         unlikely, in the extreme case this might damage your
 858                         hardware.
 859
 860         ltpc=           [NET]
 861                         Format: <io>,<irq>,<dma>
 862
 863         mac5380=        [HW,SCSI] Format:
 864                         <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 865
 866         mac53c9x=       [HW,SCSI] Format:
 867                         <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 868
 869         machvec=        [IA64] Force the use of a particular machine-vector
 870                         (machvec) in a generic kernel.
 871                         Example: machvec=hpzx1_swiotlb
 872
 873         max_loop=       [LOOP] Maximum number of loopback devices that can
 874                         be mounted
 875                         Format: <1-256>
 876
 877         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 878                         should make use of.
 879                         Using "nosmp" or "maxcpus=0" will disable SMP
 880                         entirely (the MPS table probe still happens, though).
 881                         A command-line option of "maxcpus=<NUM>", where <NUM>
 882                         is an integer greater than 0, limits the maximum number
 883                         of CPUs activated in SMP mode to <NUM>.
 884                         Using "maxcpus=1" on an SMP kernel is the trivial
 885                         case of an SMP kernel with only one CPU.
 886
 887         max_addr=[KMG]  [KNL,BOOT,ia64] All physical memory greater than or
 888                         equal to this physical address is ignored.
 889
 890         max_luns=       [SCSI] Maximum number of LUNs to probe.
 891                         Should be between 1 and 2^32-1.
 892
 893         max_report_luns=
 894                         [SCSI] Maximum number of LUNs received.
 895                         Should be between 1 and 16384.
 896
 897         mca-pentium     [BUGS=IA-32]
 898
 899         mcatest=        [IA-64]
 900
 901         mcd=            [HW,CD]
 902                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 903
 904         mcdx=           [HW,CD]
 905
 906         mce             [IA-32] Machine Check Exception
 907
 908         md=             [HW] RAID subsystems devices and level
 909                         See Documentation/md.txt.
 910
 911         mdacon=         [MDA]
 912                         Format: <first>,<last>
 913                         Specifies range of consoles to be captured by the MDA.
 914
 915         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 916                         Amount of memory to be used when the kernel is not able
 917                         to see the whole system memory or for test.
 918                         [IA-32] Use together with memmap= to avoid physical
 919                         address space collisions. Without memmap= PCI devices
 920                         could be placed at addresses belonging to unused RAM.
 921
 922         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 923                         memory.
 924
 925         memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
 926                         E820 memory map, as specified by the user.
 927                         Such memmap=exactmap lines can be constructed based on
 928                         BIOS output or other requirements. See the memmap=nn@ss
 929                         option description.
 930
 931         memmap=nn[KMG]@ss[KMG]
 932                         [KNL] Force usage of a specific region of memory
 933                         Region of memory to be used, from ss to ss+nn.
 934
 935         memmap=nn[KMG]#ss[KMG]
 936                         [KNL,ACPI] Mark specific memory as ACPI data.
 937                         Region of memory to be used, from ss to ss+nn.
 938
 939         memmap=nn[KMG]$ss[KMG]
 940                         [KNL,ACPI] Mark specific memory as reserved.
 941                         Region of memory to be used, from ss to ss+nn.
 942
 943         meye.*=         [HW] Set MotionEye Camera parameters
 944                         See Documentation/video4linux/meye.txt.
 945
 946         mga=            [HW,DRM]
 947
 948         migration_cost=
 949                         [KNL,SMP] debug: override scheduler migration costs
 950                         Format: <level-1-usecs>,<level-2-usecs>,...
 951                         This debugging option can be used to override the
 952                         default scheduler migration cost matrix. The numbers
 953                         are indexed by 'CPU domain distance'.
 954                         E.g. migration_cost=1000,2000,3000 on an SMT NUMA
 955                         box will set up an intra-core migration cost of
 956                         1 msec, an inter-core migration cost of 2 msecs,
 957                         and an inter-node migration cost of 3 msecs.
 958
 959                         WARNING: using the wrong values here can break
 960                         scheduler performance, so it's only for scheduler
 961                         development purposes, not production environments.
 962
 963         migration_debug=
 964                         [KNL,SMP] migration cost auto-detect verbosity
 965                         Format=<0|1|2>
 966                         If a system's migration matrix reported at bootup
 967                         seems erroneous then this option can be used to
 968                         increase verbosity of the detection process.
 969                         We default to 0 (no extra messages), 1 will print
 970                         some more information, and 2 will be really
 971                         verbose (probably only useful if you also have a
 972                         serial console attached to the system).
 973
 974         migration_factor=
 975                         [KNL,SMP] multiply/divide migration costs by a factor
 976                         Format=<percent>
 977                         This debug option can be used to proportionally
 978                         increase or decrease the auto-detected migration
 979                         costs for all entries of the migration matrix.
 980                         E.g. migration_factor=150 will increase migration
 981                         costs by 50%. (and thus the scheduler will be less
 982                         eager migrating cache-hot tasks)
 983                         migration_factor=80 will decrease migration costs
 984                         by 20%. (thus the scheduler will be more eager to
 985                         migrate tasks)
 986
 987                         WARNING: using the wrong values here can break
 988                         scheduler performance, so it's only for scheduler
 989                         development purposes, not production environments.
 990
 991         mousedev.tap_time=
 992                         [MOUSE] Maximum time between finger touching and
 993                         leaving touchpad surface for touch to be considered
 994                         a tap and be reported as a left button click (for
 995                         touchpads working in absolute mode only).
 996                         Format: <msecs>
 997         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
 998                         reporting absolute coordinates, such as tablets
 999         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
1000                         reporting absolute coordinates, such as tablets
1001
1002         mpu401=         [HW,OSS]
1003                         Format: <io>,<irq>
1004
1005         MTD_Partition=  [MTD]
1006                         Format: <name>,<region-number>,<size>,<offset>
1007
1008         MTD_Region=     [MTD] Format:
1009                         <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1010
1011         mtdparts=       [MTD]
1012                         See drivers/mtd/cmdline.c.
1013
1014         mtouchusb.raw_coordinates=
1015                         [HW] Make the MicroTouch USB driver use raw coordinates
1016                         ('y', default) or cooked coordinates ('n')
1017
1018         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
1019
1020         NCR_D700=       [HW,SCSI]
1021                         See header of drivers/scsi/NCR_D700.c.
1022
1023         ncr5380=        [HW,SCSI]
1024
1025         ncr53c400=      [HW,SCSI]
1026
1027         ncr53c400a=     [HW,SCSI]
1028
1029         ncr53c406a=     [HW,SCSI]
1030
1031         ncr53c8xx=      [HW,SCSI]
1032
1033         netdev=         [NET] Network devices parameters
1034                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1035                         Note that mem_start is often overloaded to mean
1036                         something different and driver-specific.
1037                         This usage is only documented in each driver source
1038                         file if at all.
1039
1040         nfsaddrs=       [NFS]
1041                         See Documentation/nfsroot.txt.
1042
1043         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
1044                         See Documentation/nfsroot.txt.
1045
1046         nfs.callback_tcpport=
1047                         [NFS] set the TCP port on which the NFSv4 callback
1048                         channel should listen.
1049
1050         nfs.idmap_cache_timeout=
1051                         [NFS] set the maximum lifetime for idmapper cache
1052                         entries.
1053
1054         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
1055
1056         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
1057                         emulation library even if a 387 maths coprocessor
1058                         is present.
1059
1060         noacpi          [LIBATA] Disables use of ACPI in libata suspend/resume
1061                         when set.
1062                         Format: <int>
1063
1064         noaliencache    [MM, NUMA] Disables the allcoation of alien caches in
1065                         the slab allocator.  Saves per-node memory, but will
1066                         impact performance on real NUMA hardware.
1067
1068         noalign         [KNL,ARM]
1069
1070         noapic          [SMP,APIC] Tells the kernel to not make use of any
1071                         IOAPICs that may be present in the system.
1072
1073         noasync         [HW,M68K] Disables async and sync negotiation for
1074                         all devices.
1075
1076         nobats          [PPC] Do not use BATs for mapping kernel lowmem
1077                         on "Classic" PPC cores.
1078
1079         nocache         [ARM]
1080
1081         nodelayacct     [KNL] Disable per-task delay accounting
1082
1083         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
1084
1085         noexec          [IA-64]
1086
1087         noexec          [IA-32,X86-64]
1088                         noexec=on: enable non-executable mappings (default)
1089                         noexec=off: disable nn-executable mappings
1090
1091         nofxsr          [BUGS=IA-32] Disables x86 floating point extended
1092                         register save and restore. The kernel will only save
1093                         legacy floating-point registers on task switch.
1094
1095         nohlt           [BUGS=ARM]
1096
1097         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
1098                         instruction doesn't work correctly and not to
1099                         use it.
1100
1101         nohalt          [IA-64] Tells the kernel not to use the power saving
1102                         function PAL_HALT_LIGHT when idle. This increases
1103                         power-consumption. On the positive side, it reduces
1104                         interrupt wake-up latency, which may improve performance
1105                         in certain environments such as networked servers or
1106                         real-time systems.
1107
1108         nohz=           [KNL] Boottime enable/disable dynamic ticks
1109                         Valid arguments: on, off
1110                         Default: on
1111
1112         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
1113
1114         noirqdebug      [IA-32] Disables the code which attempts to detect and
1115                         disable unhandled interrupt sources.
1116
1117         no_timer_check  [IA-32,X86_64,APIC] Disables the code which tests for
1118                         broken timer IRQ sources.
1119
1120         noisapnp        [ISAPNP] Disables ISA PnP code.
1121
1122         noinitrd        [RAM] Tells the kernel not to load any configured
1123                         initial RAM disk.
1124
1125         nointroute      [IA-64]
1126
1127         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
1128
1129         nolapic_timer   [IA-32,APIC] Do not use the local APIC timer.
1130
1131         noltlbs         [PPC] Do not use large page/tlb entries for kernel
1132                         lowmem mapping on PPC40x.
1133
1134         nomca           [IA-64] Disable machine check abort handling
1135
1136         nomce           [IA-32] Machine Check Exception
1137
1138         noresidual      [PPC] Don't use residual data on PReP machines.
1139
1140         noresume        [SWSUSP] Disables resume and restores original swap
1141                         space.
1142
1143         no-scroll       [VGA] Disables scrollback.
1144                         This is required for the Braillex ib80-piezo Braille
1145                         reader made by F.H. Papenmeier (Germany).
1146
1147         nosbagart       [IA-64]
1148
1149         nosep           [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1150
1151         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
1152
1153         nosync          [HW,M68K] Disables sync negotiation for all devices.
1154
1155         notsc           [BUGS=IA-32] Disable Time Stamp Counter
1156
1157         nousb           [USB] Disable the USB subsystem
1158
1159         nowb            [ARM]
1160
1161         nr_uarts=       [SERIAL] maximum number of UARTs to be registered.
1162
1163         opl3=           [HW,OSS]
1164                         Format: <io>
1165
1166         opl3sa2=        [HW,OSS] Format:
1167                         <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1168
1169         oprofile.timer= [HW]
1170                         Use timer interrupt instead of performance counters
1171
1172         optcd=          [HW,CD]
1173                         Format: <io>
1174
1175         osst=           [HW,SCSI] SCSI Tape Driver
1176                         Format: <buffer_size>,<write_threshold>
1177                         See also Documentation/scsi/st.txt.
1178
1179         panic=          [KNL] Kernel behaviour on panic
1180                         Format: <timeout>
1181
1182         parkbd.port=    [HW] Parallel port number the keyboard adapter is
1183                         connected to, default is 0.
1184                         Format: <parport#>
1185         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
1186                         0 for XT, 1 for AT (default is AT).
1187                         Format: <mode>
1188
1189         parport=        [HW,PPT] Specify parallel ports. 0 disables.
1190                         Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1191                         Use 'auto' to force the driver to use any
1192                         IRQ/DMA settings detected (the default is to
1193                         ignore detected IRQ/DMA settings because of
1194                         possible conflicts). You can specify the base
1195                         address, IRQ, and DMA settings; IRQ and DMA
1196                         should be numbers, or 'auto' (for using detected
1197                         settings on that particular port), or 'nofifo'
1198                         (to avoid using a FIFO even if it is detected).
1199                         Parallel ports are assigned in the order they
1200                         are specified on the command line, starting
1201                         with parport0.
1202
1203         parport_init_mode=      [HW,PPT]
1204                         Configure VIA parallel port to operate in
1205                         a specific mode. This is necessary on Pegasos
1206                         computer where firmware has no options for setting
1207                         up parallel port mode and sets it to spp.
1208                         Currently this function knows 686a and 8231 chips.
1209                         Format: [spp|ps2|epp|ecp|ecpepp]
1210
1211         pas2=           [HW,OSS] Format:
1212                         <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1213
1214         pas16=          [HW,SCSI]
1215                         See header of drivers/scsi/pas16.c.
1216
1217         pause_on_oops=
1218                         Halt all CPUs after the first oops has been printed for
1219                         the specified number of seconds.  This is to be used if
1220                         your oopses keep scrolling off the screen.
1221
1222         pcbit=          [HW,ISDN]
1223
1224         pcd.            [PARIDE]
1225                         See header of drivers/block/paride/pcd.c.
1226                         See also Documentation/paride.txt.
1227
1228         pci=option[,option...]  [PCI] various PCI subsystem options:
1229                 off             [IA-32] don't probe for the PCI bus
1230                 bios            [IA-32] force use of PCI BIOS, don't access
1231                                 the hardware directly. Use this if your machine
1232                                 has a non-standard PCI host bridge.
1233                 nobios          [IA-32] disallow use of PCI BIOS, only direct
1234                                 hardware access methods are allowed. Use this
1235                                 if you experience crashes upon bootup and you
1236                                 suspect they are caused by the BIOS.
1237                 conf1           [IA-32] Force use of PCI Configuration
1238                                 Mechanism 1.
1239                 conf2           [IA-32] Force use of PCI Configuration
1240                                 Mechanism 2.
1241                 nommconf        [IA-32,X86_64] Disable use of MMCONFIG for PCI
1242                                 Configuration
1243                 nomsi           [MSI] If the PCI_MSI kernel config parameter is
1244                                 enabled, this kernel boot option can be used to
1245                                 disable the use of MSI interrupts system-wide.
1246                 nosort          [IA-32] Don't sort PCI devices according to
1247                                 order given by the PCI BIOS. This sorting is
1248                                 done to get a device order compatible with
1249                                 older kernels.
1250                 biosirq         [IA-32] Use PCI BIOS calls to get the interrupt
1251                                 routing table. These calls are known to be buggy
1252                                 on several machines and they hang the machine
1253                                 when used, but on other computers it's the only
1254                                 way to get the interrupt routing table. Try
1255                                 this option if the kernel is unable to allocate
1256                                 IRQs or discover secondary PCI buses on your
1257                                 motherboard.
1258                 rom             [IA-32] Assign address space to expansion ROMs.
1259                                 Use with caution as certain devices share
1260                                 address decoders between ROMs and other
1261                                 resources.
1262                 irqmask=0xMMMM  [IA-32] Set a bit mask of IRQs allowed to be
1263                                 assigned automatically to PCI devices. You can
1264                                 make the kernel exclude IRQs of your ISA cards
1265                                 this way.
1266                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1267                                 of the PIRQ table (normally generated
1268                                 by the BIOS) if it is outside the
1269                                 F0000h-100000h range.
1270                 lastbus=N       [IA-32] Scan all buses thru bus #N. Can be
1271                                 useful if the kernel is unable to find your
1272                                 secondary buses and you want to tell it
1273                                 explicitly which ones they are.
1274                 assign-busses   [IA-32] Always assign all PCI bus
1275                                 numbers ourselves, overriding
1276                                 whatever the firmware may have done.
1277                 usepirqmask     [IA-32] Honor the possible IRQ mask stored
1278                                 in the BIOS $PIR table. This is needed on
1279                                 some systems with broken BIOSes, notably
1280                                 some HP Pavilion N5400 and Omnibook XE3
1281                                 notebooks. This will have no effect if ACPI
1282                                 IRQ routing is enabled.
1283                 noacpi          [IA-32] Do not use ACPI for IRQ routing
1284                                 or for PCI scanning.
1285                 routeirq        Do IRQ routing for all PCI devices.
1286                                 This is normally done in pci_enable_device(),
1287                                 so this option is a temporary workaround
1288                                 for broken drivers that don't call it.
1289                 firmware        [ARM] Do not re-enumerate the bus but instead
1290                                 just use the configuration from the
1291                                 bootloader. This is currently used on
1292                                 IXP2000 systems where the bus has to be
1293                                 configured a certain way for adjunct CPUs.
1294                 noearly         [X86] Don't do any early type 1 scanning.
1295                                 This might help on some broken boards which
1296                                 machine check when some devices' config space
1297                                 is read. But various workarounds are disabled
1298                                 and some IOMMU drivers will not work.
1299                 bfsort          Sort PCI devices into breadth-first order.
1300                                 This sorting is done to get a device
1301                                 order compatible with older (<= 2.4) kernels.
1302                 nobfsort        Don't sort PCI devices into breadth-first order.
1303                 cbiosize=nn[KMG]        The fixed amount of bus space which is
1304                                 reserved for the CardBus bridge's IO window.
1305                                 The default value is 256 bytes.
1306                 cbmemsize=nn[KMG]       The fixed amount of bus space which is
1307                                 reserved for the CardBus bridge's memory
1308                                 window. The default value is 64 megabytes.
1309
1310         pcmv=           [HW,PCMCIA] BadgePAD 4
1311
1312         pd.             [PARIDE]
1313                         See Documentation/paride.txt.
1314
1315         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1316                         boot time.
1317                         Format: { 0 | 1 }
1318                         See arch/parisc/kernel/pdc_chassis.c
1319
1320         pf.             [PARIDE]
1321                         See Documentation/paride.txt.
1322
1323         pg.             [PARIDE]
1324                         See Documentation/paride.txt.
1325
1326         pirq=           [SMP,APIC] Manual mp-table setup
1327                         See Documentation/i386/IO-APIC.txt.
1328
1329         plip=           [PPT,NET] Parallel port network link
1330                         Format: { parport<nr> | timid | 0 }
1331                         See also Documentation/parport.txt.
1332
1333         pnpacpi=        [ACPI]
1334                         { off }
1335
1336         pnpbios=        [ISAPNP]
1337                         { on | off | curr | res | no-curr | no-res }
1338
1339         pnp_reserve_irq=
1340                         [ISAPNP] Exclude IRQs for the autoconfiguration
1341
1342         pnp_reserve_dma=
1343                         [ISAPNP] Exclude DMAs for the autoconfiguration
1344
1345         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1346                         Ranges are in pairs (I/O port base and size).
1347
1348         pnp_reserve_mem=
1349                         [ISAPNP] Exclude memory regions for the
1350                         autoconfiguration.
1351                         Ranges are in pairs (memory base and size).
1352
1353         profile=        [KNL] Enable kernel profiling via /proc/profile
1354                         Format: [schedule,]<number>
1355                         Param: "schedule" - profile schedule points.
1356                         Param: <number> - step/bucket size as a power of 2 for
1357                                 statistical time based profiling.
1358                         Param: "sleep" - profile D-state sleeping (millisecs)
1359
1360         processor.max_cstate=   [HW,ACPI]
1361                         Limit processor to maximum C-state
1362                         max_cstate=9 overrides any DMI blacklist limit.
1363
1364         processor.nocst [HW,ACPI]
1365                         Ignore the _CST method to determine C-states,
1366                         instead using the legacy FADT method
1367
1368         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1369                         before loading.
1370                         See Documentation/ramdisk.txt.
1371
1372         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1373                         probe for; one of (bare|imps|exps|lifebook|any).
1374         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1375                         per second.
1376         psmouse.resetafter=     [HW,MOUSE]
1377                         Try to reset the device after so many bad packets
1378                         (0 = never).
1379         psmouse.resolution=
1380                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1381         psmouse.smartscroll=
1382                         [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1383                         0 = disabled, 1 = enabled (default).
1384
1385         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1386                         Format:
1387                         <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1388
1389         pt.             [PARIDE]
1390                         See Documentation/paride.txt.
1391
1392         quiet           [KNL] Disable most log messages
1393
1394         r128=           [HW,DRM]
1395
1396         raid=           [HW,RAID]
1397                         See Documentation/md.txt.
1398
1399         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1400                         See Documentation/ramdisk.txt.
1401
1402         ramdisk_blocksize=      [RAM]
1403                         See Documentation/ramdisk.txt.
1404
1405         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1406                         New name for the ramdisk parameter.
1407                         See Documentation/ramdisk.txt.
1408
1409         rcu.blimit=     [KNL,BOOT] Set maximum number of finished
1410                         RCU callbacks to process in one batch.
1411
1412         rcu.qhimark=    [KNL,BOOT] Set threshold of queued
1413                         RCU callbacks over which batch limiting is disabled.
1414
1415         rcu.qlowmark=   [KNL,BOOT] Set threshold of queued
1416                         RCU callbacks below which batch limiting is re-enabled.
1417
1418         rdinit=         [KNL]
1419                         Format: <full_path>
1420                         Run specified binary instead of /init from the ramdisk,
1421                         used for early userspace startup. See initrd.
1422
1423         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1424                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1425                         See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1426
1427         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1428
1429         reservetop=     [IA-32]
1430                         Format: nn[KMG]
1431                         Reserves a hole at the top of the kernel virtual
1432                         address space.
1433
1434         reset_devices   [KNL] Force drivers to reset the underlying device
1435                         during initialization.
1436
1437         resume=         [SWSUSP]
1438                         Specify the partition device for software suspend
1439
1440         resume_offset=  [SWSUSP]
1441                         Specify the offset from the beginning of the partition
1442                         given by "resume=" at which the swap header is located,
1443                         in <PAGE_SIZE> units (needed only for swap files).
1444                         See  Documentation/power/swsusp-and-swap-files.txt
1445
1446         retain_initrd   [RAM] Keep initrd memory after extraction
1447
1448         rhash_entries=  [KNL,NET]
1449                         Set number of hash buckets for route cache
1450
1451         riscom8=        [HW,SERIAL]
1452                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1453
1454         ro              [KNL] Mount root device read-only on boot
1455
1456         root=           [KNL] Root filesystem
1457
1458         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1459                         mount the root filesystem
1460
1461         rootflags=      [KNL] Set root filesystem mount option string
1462
1463         rootfstype=     [KNL] Set root filesystem type
1464
1465         rw              [KNL] Mount root device read-write on boot
1466
1467         S               [KNL] Run init in single mode
1468
1469         sa1100ir        [NET]
1470                         See drivers/net/irda/sa1100_ir.c.
1471
1472         sb=             [HW,OSS]
1473                         Format: <io>,<irq>,<dma>,<dma2>
1474
1475         sbni=           [NET] Granch SBNI12 leased line adapter
1476
1477         sbpcd=          [HW,CD] Soundblaster CD adapter
1478                         Format: <io>,<type>
1479                         See a comment before function sbpcd_setup() in
1480                         drivers/cdrom/sbpcd.c.
1481
1482         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1483                         Format: <io>[,<timeout>[,<isapnp>]]
1484
1485         scsi_debug_*=   [SCSI]
1486                         See drivers/scsi/scsi_debug.c.
1487
1488         scsi_default_dev_flags=
1489                         [SCSI] SCSI default device flags
1490                         Format: <integer>
1491
1492         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1493                         Format: <vendor>:<model>:<flags>
1494                         (flags are integer value)
1495
1496         scsi_logging=   [SCSI]
1497
1498         scsi_mod.scan=  [SCSI] sync (default) scans SCSI busses as they are
1499                         discovered.  async scans them in kernel threads,
1500                         allowing boot to proceed.  none ignores them, expecting
1501                         user space to do the scan.
1502
1503         selinux         [SELINUX] Disable or enable SELinux at boot time.
1504                         Format: { "0" | "1" }
1505                         See security/selinux/Kconfig help text.
1506                         0 -- disable.
1507                         1 -- enable.
1508                         Default value is set via kernel config option.
1509                         If enabled at boot time, /selinux/disable can be used
1510                         later to disable prior to initial policy load.
1511
1512         selinux_compat_net =
1513                         [SELINUX] Set initial selinux_compat_net flag value.
1514                         Format: { "0" | "1" }
1515                         0 -- use new secmark-based packet controls
1516                         1 -- use legacy packet controls
1517                         Default value is 0 (preferred).
1518                         Value can be changed at runtime via
1519                         /selinux/compat_net.
1520
1521         serialnumber    [BUGS=IA-32]
1522
1523         sg_def_reserved_size=   [SCSI]
1524
1525         shapers=        [NET]
1526                         Maximal number of shapers.
1527
1528         sim710=         [SCSI,HW]
1529                         See header of drivers/scsi/sim710.c.
1530
1531         simeth=         [IA-64]
1532         simscsi=
1533
1534         sjcd=           [HW,CD]
1535                         Format: <io>,<irq>,<dma>
1536                         See header of drivers/cdrom/sjcd.c.
1537
1538         slram=          [HW,MTD]
1539
1540         smart2=         [HW]
1541                         Format: <io1>[,<io2>[,...,<io8>]]
1542
1543         snd-ad1816a=    [HW,ALSA]
1544
1545         snd-ad1848=     [HW,ALSA]
1546
1547         snd-ali5451=    [HW,ALSA]
1548
1549         snd-als100=     [HW,ALSA]
1550
1551         snd-als4000=    [HW,ALSA]
1552
1553         snd-azt2320=    [HW,ALSA]
1554
1555         snd-cmi8330=    [HW,ALSA]
1556
1557         snd-cmipci=     [HW,ALSA]
1558
1559         snd-cs4231=     [HW,ALSA]
1560
1561         snd-cs4232=     [HW,ALSA]
1562
1563         snd-cs4236=     [HW,ALSA]
1564
1565         snd-cs4281=     [HW,ALSA]
1566
1567         snd-cs46xx=     [HW,ALSA]
1568
1569         snd-dt019x=     [HW,ALSA]
1570
1571         snd-dummy=      [HW,ALSA]
1572
1573         snd-emu10k1=    [HW,ALSA]
1574
1575         snd-ens1370=    [HW,ALSA]
1576
1577         snd-ens1371=    [HW,ALSA]
1578
1579         snd-es968=      [HW,ALSA]
1580
1581         snd-es1688=     [HW,ALSA]
1582
1583         snd-es18xx=     [HW,ALSA]
1584
1585         snd-es1938=     [HW,ALSA]
1586
1587         snd-es1968=     [HW,ALSA]
1588
1589         snd-fm801=      [HW,ALSA]
1590
1591         snd-gusclassic= [HW,ALSA]
1592
1593         snd-gusextreme= [HW,ALSA]
1594
1595         snd-gusmax=     [HW,ALSA]
1596
1597         snd-hdsp=       [HW,ALSA]
1598
1599         snd-ice1712=    [HW,ALSA]
1600
1601         snd-intel8x0=   [HW,ALSA]
1602
1603         snd-interwave=  [HW,ALSA]
1604
1605         snd-interwave-stb=
1606                         [HW,ALSA]
1607
1608         snd-korg1212=   [HW,ALSA]
1609
1610         snd-maestro3=   [HW,ALSA]
1611
1612         snd-mpu401=     [HW,ALSA]
1613
1614         snd-mtpav=      [HW,ALSA]
1615
1616         snd-nm256=      [HW,ALSA]
1617
1618         snd-opl3sa2=    [HW,ALSA]
1619
1620         snd-opti92x-ad1848=
1621                         [HW,ALSA]
1622
1623         snd-opti92x-cs4231=
1624                         [HW,ALSA]
1625
1626         snd-opti93x=    [HW,ALSA]
1627
1628         snd-pmac=       [HW,ALSA]
1629
1630         snd-rme32=      [HW,ALSA]
1631
1632         snd-rme96=      [HW,ALSA]
1633
1634         snd-rme9652=    [HW,ALSA]
1635
1636         snd-sb8=        [HW,ALSA]
1637
1638         snd-sb16=       [HW,ALSA]
1639
1640         snd-sbawe=      [HW,ALSA]
1641
1642         snd-serial=     [HW,ALSA]
1643
1644         snd-sgalaxy=    [HW,ALSA]
1645
1646         snd-sonicvibes= [HW,ALSA]
1647
1648         snd-sun-amd7930=
1649                         [HW,ALSA]
1650
1651         snd-sun-cs4231= [HW,ALSA]
1652
1653         snd-trident=    [HW,ALSA]
1654
1655         snd-usb-audio=  [HW,ALSA,USB]
1656
1657         snd-via82xx=    [HW,ALSA]
1658
1659         snd-virmidi=    [HW,ALSA]
1660
1661         snd-wavefront=  [HW,ALSA]
1662
1663         snd-ymfpci=     [HW,ALSA]
1664
1665         sonycd535=      [HW,CD]
1666                         Format: <io>[,<irq>]
1667
1668         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1669                         See Documentation/sonypi.txt
1670
1671         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1672                         See Documentation/specialix.txt.
1673
1674         spia_io_base=   [HW,MTD]
1675         spia_fio_base=
1676         spia_pedr=
1677         spia_peddr=
1678
1679         sscape=         [HW,OSS]
1680                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1681
1682         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1683                         See Documentation/scsi/st.txt.
1684
1685         st0x=           [HW,SCSI]
1686                         See header of drivers/scsi/seagate.c.
1687
1688         sti=            [PARISC,HW]
1689                         Format: <num>
1690                         Set the STI (builtin display/keyboard on the HP-PARISC
1691                         machines) console (graphic card) which should be used
1692                         as the initial boot-console.
1693                         See also comment in drivers/video/console/sticore.c.
1694
1695         sti_font=       [HW]
1696                         See comment in drivers/video/console/sticore.c.
1697
1698         stifb=          [HW]
1699                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1700
1701         sunrpc.pool_mode=
1702                         [NFS]
1703                         Control how the NFS server code allocates CPUs to
1704                         service thread pools.  Depending on how many NICs
1705                         you have and where their interrupts are bound, this
1706                         option will affect which CPUs will do NFS serving.
1707                         Note: this parameter cannot be changed while the
1708                         NFS server is running.
1709
1710                         auto        the server chooses an appropriate mode
1711                                     automatically using heuristics
1712                         global      a single global pool contains all CPUs
1713                         percpu      one pool for each CPU
1714                         pernode     one pool for each NUMA node (equivalent
1715                                     to global on non-NUMA machines)
1716
1717         swiotlb=        [IA-64] Number of I/O TLB slabs
1718
1719         switches=       [HW,M68k]
1720
1721         sym53c416=      [HW,SCSI]
1722                         See header of drivers/scsi/sym53c416.c.
1723
1724         sysrq_always_enabled
1725                         [KNL]
1726                         Ignore sysrq setting - this boot parameter will
1727                         neutralize any effect of /proc/sys/kernel/sysrq.
1728                         Useful for debugging.
1729
1730         t128=           [HW,SCSI]
1731                         See header of drivers/scsi/t128.c.
1732
1733         tdfx=           [HW,DRM]
1734
1735         thash_entries=  [KNL,NET]
1736                         Set number of hash buckets for TCP connection
1737
1738         time            Show timing data prefixed to each printk message line
1739
1740         clocksource=    [GENERIC_TIME] Override the default clocksource
1741                         Override the default clocksource and use the clocksource
1742                         with the name specified.
1743
1744         tipar.timeout=  [HW,PPT]
1745                         Set communications timeout in tenths of a second
1746                         (default 15).
1747
1748         tipar.delay=    [HW,PPT]
1749                         Set inter-bit delay in microseconds (default 10).
1750
1751         tmc8xx=         [HW,SCSI]
1752                         See header of drivers/scsi/seagate.c.
1753
1754         tmscsim=        [HW,SCSI]
1755                         See comment before function dc390_setup() in
1756                         drivers/scsi/tmscsim.c.
1757
1758         tp720=          [HW,PS2]
1759
1760         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1761                         Format:
1762                         <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1763
1764         tsdev.xres=     [TS] Horizontal screen resolution.
1765         tsdev.yres=     [TS] Vertical screen resolution.
1766
1767         turbografx.map[2|3]=    [HW,JOY]
1768                         TurboGraFX parallel port interface
1769                         Format:
1770                         <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1771                         See also Documentation/input/joystick-parport.txt
1772
1773         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1774                         See header of drivers/scsi/u14-34f.c.
1775
1776         uart401=        [HW,OSS]
1777                         Format: <io>,<irq>
1778
1779         uart6850=       [HW,OSS]
1780                         Format: <io>,<irq>
1781
1782         uhci-hcd.ignore_oc=
1783                         [USB] Ignore overcurrent events (default N).
1784                         Some badly-designed motherboards generate lots of
1785                         bogus events, for ports that aren't wired to
1786                         anything.  Set this parameter to avoid log spamming.
1787                         Note that genuine overcurrent events won't be
1788                         reported either.
1789
1790         usbcore.autosuspend=
1791                         [USB] The autosuspend time delay (in seconds) used
1792                         for newly-detected USB devices (default 2).  This
1793                         is the time required before an idle device will be
1794                         autosuspended.  Devices for which the delay is set
1795                         to 0 won't be autosuspended at all.
1796
1797         usbhid.mousepoll=
1798                         [USBHID] The interval which mice are to be polled at.
1799
1800         vdso=           [IA-32,SH]
1801                         vdso=1: enable VDSO (default)
1802                         vdso=0: disable VDSO mapping
1803
1804         video=          [FB] Frame buffer configuration
1805                         See Documentation/fb/modedb.txt.
1806
1807         vga=            [BOOT,IA-32] Select a particular video mode
1808                         See Documentation/i386/boot.txt and
1809                         Documentation/svga.txt.
1810                         Use vga=ask for menu.
1811                         This is actually a boot loader parameter; the value is
1812                         passed to the kernel using a special protocol.
1813
1814         vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1815                         size of <nn>. This can be used to increase the
1816                         minimum size (128MB on x86). It can also be used to
1817                         decrease the size and leave more room for directly
1818                         mapped kernel RAM.
1819
1820         vmhalt=         [KNL,S390] Perform z/VM CP command after system halt.
1821                         Format: <command>
1822
1823         vmpanic=        [KNL,S390] Perform z/VM CP command after kernel panic.
1824                         Format: <command>
1825
1826         vmpoff=         [KNL,S390] Perform z/VM CP command after power off.
1827                         Format: <command>
1828
1829         waveartist=     [HW,OSS]
1830                         Format: <io>,<irq>,<dma>,<dma2>
1831
1832         wd33c93=        [HW,SCSI]
1833                         See header of drivers/scsi/wd33c93.c.
1834
1835         wd7000=         [HW,SCSI]
1836                         See header of drivers/scsi/wd7000.c.
1837
1838         wdt=            [WDT] Watchdog
1839                         See Documentation/watchdog/watchdog.txt.
1840
1841         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1842         xd_geo=         See header of drivers/block/xd.c.
1843
1844         xirc2ps_cs=     [NET,PCMCIA]
1845                         Format:
1846                         <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1847
1848         norandmaps      Don't use address space randomization
1849                         Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1850
1851         unwind_debug=N  N > 0 will enable dwarf2 unwinder debugging
1852                         This is useful to get more information why
1853                         you got a "dwarf2 unwinder stuck"
1854
1855 ______________________________________________________________________
1856
1857 TODO:
1858
1859         Add documentation for ALSA options.
1860         Add more DRM drivers.