Documentation/kernel-parameters.txt

   1 February 2003             Kernel Parameters                     v2.5.59
   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 The text in square brackets at the beginning of the description state the
  21 restrictions on the kernel for the said kernel parameter to be valid. The
  22 restrictions referred to are that the relevant option is valid if:
  23
  24         ACPI    ACPI support is enabled.
  25         ALSA    ALSA sound support is enabled.
  26         APIC    APIC support is enabled.
  27         APM     Advanced Power Management support is enabled.
  28         AX25    Appropriate AX.25 support is enabled.
  29         CD      Appropriate CD support is enabled.
  30         DEVFS   devfs support is enabled.
  31         DRM     Direct Rendering Management support is enabled.
  32         EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
  33         EFI     EFI Partitioning (GPT) is enabled
  34         EIDE    EIDE/ATAPI support is enabled.
  35         FB      The frame buffer device is enabled.
  36         HW      Appropriate hardware is enabled.
  37         IA-32   IA-32 aka i386 architecture is enabled.
  38         IA-64   IA-64 architecture is enabled.
  39         IOSCHED More than one I/O scheduler is enabled.
  40         IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
  41         ISAPNP  ISA PnP code is enabled.
  42         ISDN    Appropriate ISDN support is enabled.
  43         JOY     Appropriate joystick support is enabled.
  44         LP      Printer support is enabled.
  45         LOOP    Loopback device support is enabled.
  46         M68k    M68k architecture is enabled.
  47                         These options have more detailed description inside of
  48                         Documentation/m68k/kernel-options.txt.
  49         MCA     MCA bus support is enabled.
  50         MDA     MDA console support is enabled.
  51         MOUSE   Appropriate mouse support is enabled.
  52         MTD     MTD support is enabled.
  53         NET     Appropriate network support is enabled.
  54         NUMA    NUMA support is enabled.
  55         NFS     Appropriate NFS support is enabled.
  56         OSS     OSS sound support is enabled.
  57         PARIDE  The ParIDE subsystem is enabled.
  58         PARISC  The PA-RISC architecture is enabled.
  59         PCI     PCI bus support is enabled.
  60         PCMCIA  The PCMCIA subsystem is enabled.
  61         PNP     Plug & Play support is enabled.
  62         PPC     PowerPC architecture is enabled.
  63         PPT     Parallel port support is enabled.
  64         PS2     Appropriate PS/2 support is enabled.
  65         RAM     RAM disk support is enabled.
  66         S390    S390 architecture is enabled.
  67         SCSI    Appropriate SCSI support is enabled.
  68                         A lot of drivers has their options described inside of
  69                         Documentation/scsi/.
  70         SELINUX SELinux support is enabled.
  71         SERIAL  Serial support is enabled.
  72         SMP     The kernel is an SMP kernel.
  73         SPARC   Sparc architecture is enabled.
  74         SWSUSP  Software suspension is enabled.
  75         TS      Appropriate touchscreen support is enabled.
  76         USB     USB support is enabled.
  77         USBHID  USB Human Interface Device support is enabled.
  78         V4L     Video For Linux support is enabled.
  79         VGA     The VGA console has been enabled.
  80         VT      Virtual terminal support is enabled.
  81         WDT     Watchdog support is enabled.
  82         XT      IBM PC/XT MFM hard disk support is enabled.
  83         X86-64  X86-64 architecture is enabled.
  84                         More X86-64 boot options can be found in
  85                         Documentation/x86_64/boot-options.txt .
  86
  87 In addition, the following text indicates that the option:
  88
  89         BUGS=   Relates to possible processor bugs on the said processor.
  90         KNL     Is a kernel start-up parameter.
  91         BOOT    Is a boot loader parameter.
  92
  93 Parameters denoted with BOOT are actually interpreted by the boot
  94 loader, and have no meaning to the kernel directly.
  95 Do not modify the syntax of boot loader parameters without extreme
  96 need or coordination with <Documentation/i386/boot.txt>.
  97
  98 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  99 a trailing = on the name of any parameter states that that parameter will
 100 be entered as an environment variable, whereas its absence indicates that
 101 it will appear as a kernel argument readable via /proc/cmdline by programs
 102 running once the system is up.
 103
 104         53c7xx=         [HW,SCSI] Amiga SCSI controllers
 105                         See header of drivers/scsi/53c7xx.c.
 106                         See also Documentation/scsi/ncr53c7xx.txt.
 107
 108         acpi=           [HW,ACPI] Advanced Configuration and Power Interface
 109                         Format: { force | off | ht | strict }
 110                         force -- enable ACPI if default was off
 111                         off -- disable ACPI if default was on
 112                         noirq -- do not use ACPI for IRQ routing
 113                         ht -- run only enough ACPI to enable Hyper Threading
 114                         strict --  Be less tolerant of platforms that are not
 115                                 strictly ACPI specification compliant.
 116
 117                         See also Documentation/pm.txt, pci=noacpi
 118
 119         acpi_sleep=     [HW,ACPI] Sleep options
 120                         Format: { s3_bios, s3_mode }
 121                         See Documentation/power/video.txt
 122
 123         acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 124                         Format: { level | edge |  high | low }
 125
 126         acpi_irq_balance        [HW,ACPI] ACPI will balance active IRQs
 127                                 default in APIC mode
 128
 129         acpi_irq_nobalance      [HW,ACPI] ACPI will not move active IRQs (default)
 130                                 default in PIC mode
 131
 132         acpi_irq_pci=   [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
 133                         Format: <irq>,<irq>...
 134
 135         acpi_irq_isa=   [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
 136                         Format: <irq>,<irq>...
 137
 138         acpi_osi=       [HW,ACPI] empty param disables _OSI
 139
 140         acpi_serialize  [HW,ACPI] force serialization of AML methods
 141
 142         acpi_skip_timer_override [HW,ACPI]
 143                         Recognize and ignore IRQ0/pin2 Interrupt Override.
 144                         For broken nForce2 BIOS resulting in XT-PIC timer.
 145
 146         acpi_dbg_layer= [HW,ACPI]
 147                         Format: <int>
 148                         Each bit of the <int> indicates an acpi debug layer,
 149                         1: enable, 0: disable. It is useful for boot time
 150                         debugging. After system has booted up, it can be set
 151                         via /proc/acpi/debug_layer.
 152
 153         acpi_dbg_level= [HW,ACPI]
 154                         Format: <int>
 155                         Each bit of the <int> indicates an acpi debug level,
 156                         1: enable, 0: disable. It is useful for boot time
 157                         debugging. After system has booted up, it can be set
 158                         via /proc/acpi/debug_level.
 159
 160         acpi_fake_ecdt  [HW,ACPI] Workaround failure due to BIOS lacking ECDT
 161
 162         ad1816=         [HW,OSS]
 163                         Format: <io>,<irq>,<dma>,<dma2>
 164                         See also Documentation/sound/oss/AD1816.
 165
 166         ad1848=         [HW,OSS]
 167                         Format: <io>,<irq>,<dma>,<dma2>,<type>
 168
 169         adlib=          [HW,OSS]
 170                         Format: <io>
 171
 172         advansys=       [HW,SCSI]
 173                         See header of drivers/scsi/advansys.c.
 174
 175         advwdt=         [HW,WDT] Advantech WDT
 176                         Format: <iostart>,<iostop>
 177
 178         aedsp16=        [HW,OSS] Audio Excel DSP 16
 179                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 180                         See also header of sound/oss/aedsp16.c.
 181
 182         aha152x=        [HW,SCSI]
 183                         See Documentation/scsi/aha152x.txt.
 184
 185         aha1542=        [HW,SCSI]
 186                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 187
 188         aic7xxx=        [HW,SCSI]
 189                         See Documentation/scsi/aic7xxx.txt.
 190
 191         aic79xx=        [HW,SCSI]
 192                         See Documentation/scsi/aic79xx.txt.
 193
 194         AM53C974=       [HW,SCSI]
 195                         Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
 196                         See also header of drivers/scsi/AM53C974.c.
 197
 198         amijoy.map=     [HW,JOY] Amiga joystick support
 199                         Map of devices attached to JOY0DAT and JOY1DAT
 200                         Format: <a>,<b>
 201                         See also Documentation/kernel/input/joystick.txt
 202
 203         analog.map=     [HW,JOY] Analog joystick and gamepad support
 204                         Specifies type or capabilities of an analog joystick
 205                         connected to one of 16 gameports
 206                         Format: <type1>,<type2>,..<type16>
 207
 208         apc=            [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
 209                         Format: noidle
 210                         Disable APC CPU standby support. SPARCstation-Fox does
 211                         not play well with APC CPU idle - disable it if you have
 212                         APC and your system crashes randomly.
 213
 214         apic=           [APIC,i386] Change the output verbosity  whilst booting
 215                         Format: { quiet (default) | verbose | debug }
 216                         Change the amount of debugging information output
 217                         when initialising the APIC and IO-APIC components.
 218
 219         apm=            [APM] Advanced Power Management
 220                         See header of arch/i386/kernel/apm.c.
 221
 222         applicom=       [HW]
 223                         Format: <mem>,<irq>
 224
 225         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 226                         Format: <io>,<irq>,<nodeID>
 227
 228         ataflop=        [HW,M68k]
 229
 230         atarimouse=     [HW,MOUSE] Atari Mouse
 231
 232         atascsi=        [HW,SCSI] Atari SCSI
 233
 234         atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 235                         EzKey and similar keyboards
 236
 237         atkbd.reset=    [HW] Reset keyboard during initialization
 238
 239         atkbd.set=      [HW] Select keyboard code set
 240                         Format: <int> (2 = AT (default) 3 = PS/2)
 241
 242         atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 243                         keyboards
 244
 245         atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 246                         Format: <bool> (0 = real, 1 = synthetic (default))
 247
 248         atkbd.softrepeat=
 249                         [HW] Use software keyboard repeat
 250
 251         autotest        [IA64]
 252
 253         awe=            [HW,OSS] AWE32/SB32/AWE64 wave table synth
 254                         Format: <io>,<memsize>,<isapnp>
 255
 256         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 257                         Format: <io>,0x79 (?)
 258
 259         baycom_epp=     [HW,AX25]
 260                         Format: <io>,<mode>
 261
 262         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 263                         Format: <io>,<mode>
 264                         See header of drivers/net/hamradio/baycom_par.c.
 265
 266         baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 267                         Format: <io>,<irq>,<mode>[,<baud>]
 268                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 269
 270         baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 271                         Format: <io>,<irq>,<mode>
 272                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 273
 274         blkmtd_device=  [HW,MTD]
 275         blkmtd_erasesz=
 276         blkmtd_ro=
 277         blkmtd_bs=
 278         blkmtd_count=
 279
 280         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 281         bttv.radio=     Most important insmod options are available as kernel args too.
 282         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 283         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 284
 285         BusLogic=       [HW,SCSI]
 286                         See drivers/scsi/BusLogic.c, comment before function
 287                         BusLogic_ParseDriverOptions().
 288
 289         c101=           [NET] Moxa C101 synchronous serial card
 290
 291         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 292                         Sometimes CPU hardware bugs make them report the cache
 293                         size incorrectly. The kernel will attempt work arounds
 294                         to fix known problems, but for some CPUs it is not
 295                         possible to determine what the correct size should be.
 296                         This option provides an override for these situations.
 297
 298         cdu31a=         [HW,CD]
 299                         Format: <io>,<irq>[,PAS]
 300                         See header of drivers/cdrom/cdu31a.c.
 301
 302         chandev=        [HW,NET] Generic channel device initialisation
 303
 304         checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 305                         Format: { "0" | "1" }
 306                         See security/selinux/Kconfig help text.
 307                         0 -- check protection applied by kernel (includes any implied execute protection).
 308                         1 -- check protection requested by application.
 309                         Default value is set via a kernel config option.
 310                         Value can be changed at runtime via /selinux/checkreqprot.
 311
 312         clock=          [BUGS=IA-32, HW] gettimeofday timesource override.
 313                         Forces specified timesource (if avaliable) to be used
 314                         when calculating gettimeofday(). If specicified timesource
 315                         is not avalible, it defaults to PIT.
 316                         Format: { pit | tsc | cyclone | pmtmr }
 317
 318         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
 319                         Format: disable
 320
 321         cm206=          [HW,CD]
 322                         Format: { auto | [<io>,][<irq>] }
 323
 324         com20020=       [HW,NET] ARCnet - COM20020 chipset
 325                         Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 326
 327         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 328                         Format: <io>[,<irq>]
 329
 330         com90xx=        [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
 331                         Format: <io>[,<irq>[,<memstart>]]
 332
 333         condev=         [HW,S390] console device
 334         conmode=
 335
 336         console=        [KNL] Output console device and options.
 337
 338                 tty<n>  Use the virtual console device <n>.
 339
 340                 ttyS<n>[,options]
 341                         Use the specified serial port.  The options are of
 342                         the form "bbbbpn", where "bbbb" is the baud rate,
 343                         "p" is parity ("n", "o", or "e"), and "n" is bits.
 344                         Default is "9600n8".
 345
 346                         See also Documentation/serial-console.txt.
 347
 348                 uart,io,<addr>[,options]
 349                 uart,mmio,<addr>[,options]
 350                         Start an early, polled-mode console on the 8250/16550
 351                         UART at the specified I/O port or MMIO address,
 352                         switching to the matching ttyS device later.  The
 353                         options are the same as for ttyS, above.
 354
 355         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 356                         Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 357
 358         cpia_pp=        [HW,PPT]
 359                         Format: { parport<nr> | auto | none }
 360
 361         crashkernel=nn[KMG]@ss[KMG]
 362                         [KNL] Reserve a chunk of physical memory to
 363                         hold a kernel to switch to with kexec on panic.
 364
 365         cs4232=         [HW,OSS]
 366                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 367
 368         cs89x0_dma=     [HW,NET]
 369                         Format: <dma>
 370
 371         cs89x0_media=   [HW,NET]
 372                         Format: { rj45 | aui | bnc }
 373
 374         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 375
 376         dasd=           [HW,NET]
 377                         See header of drivers/s390/block/dasd_devmap.c.
 378
 379         db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 380                         (one device per port)
 381                         Format: <port#>,<type>
 382                         See also Documentation/input/joystick-parport.txt
 383
 384         debug           [KNL] Enable kernel debugging (events log level).
 385
 386         decnet=         [HW,NET]
 387                         Format: <area>[,<node>]
 388                         See also Documentation/networking/decnet.txt.
 389
 390         devfs=          [DEVFS]
 391                         See Documentation/filesystems/devfs/boot-options.
 392
 393         dhash_entries=  [KNL]
 394                         Set number of hash buckets for dentry cache.
 395
 396         digi=           [HW,SERIAL]
 397                         IO parameters + enable/disable command.
 398
 399         digiepca=       [HW,SERIAL]
 400                         See drivers/char/README.epca and
 401                         Documentation/digiepca.txt.
 402
 403         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 404                         support available.
 405                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 406
 407         dmasound=       [HW,OSS] Sound subsystem buffers
 408
 409         dscc4.setup=    [NET]
 410
 411         dtc3181e=       [HW,SCSI]
 412
 413         earlyprintk=    [IA-32, X86-64]
 414                         earlyprintk=vga
 415                         earlyprintk=serial[,ttySn[,baudrate]]
 416
 417                         Append ,keep to not disable it when the real console
 418                         takes over.
 419
 420                         Only vga or serial at a time, not both.
 421
 422                         Currently only ttyS0 and ttyS1 are supported.
 423
 424                         Interaction with the standard serial driver is not
 425                         very good.
 426
 427                         The VGA output is eventually overwritten by the real
 428                         console.
 429
 430         eata=           [HW,SCSI]
 431
 432         eda=            [HW,PS2]
 433
 434         edb=            [HW,PS2]
 435
 436         edd=            [EDD]
 437                         Format: {"of[f]" | "sk[ipmbr]"}
 438                         See comment in arch/i386/boot/edd.S
 439
 440         eicon=          [HW,ISDN]
 441                         Format: <id>,<membase>,<irq>
 442
 443         eisa_irq_edge=  [PARISC,HW]
 444                         See header of drivers/parisc/eisa.c.
 445
 446         elanfreq=       [IA-32]
 447                         See comment before function elanfreq_setup() in
 448                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 449
 450         elevator=       [IOSCHED]
 451                         Format: {"as"|"cfq"|"deadline"|"noop"}
 452                         See Documentation/block/as-iosched.txt
 453                         and Documentation/block/deadline-iosched.txt for details.
 454         elfcorehdr=     [IA-32]
 455                         Specifies physical address of start of kernel core image
 456                         elf header.
 457                         See Documentation/kdump.txt for details.
 458
 459         enforcing       [SELINUX] Set initial enforcing status.
 460                         Format: {"0" | "1"}
 461                         See security/selinux/Kconfig help text.
 462                         0 -- permissive (log only, no denials).
 463                         1 -- enforcing (deny and log).
 464                         Default value is 0.
 465                         Value can be changed at runtime via /selinux/enforce.
 466
 467         es1370=         [HW,OSS]
 468                         Format: <lineout>[,<micbias>]
 469                         See also header of sound/oss/es1370.c.
 470
 471         es1371=         [HW,OSS]
 472                         Format: <spdif>,[<nomix>,[<amplifier>]]
 473                         See also header of sound/oss/es1371.c.
 474
 475         ether=          [HW,NET] Ethernet cards parameters
 476                         This option is obsoleted by the "netdev=" option, which
 477                         has equivalent usage. See its documentation for details.
 478
 479         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 480                         Format: <io>[,<irq>]
 481
 482         fd_mcs=         [HW,SCSI]
 483                         See header of drivers/scsi/fd_mcs.c.
 484
 485         fdomain=        [HW,SCSI]
 486                         See header of drivers/scsi/fdomain.c.
 487
 488         floppy=         [HW]
 489                         See Documentation/floppy.txt.
 490
 491         ftape=          [HW] Floppy Tape subsystem debugging options.
 492                         See Documentation/ftape.txt.
 493
 494         gamecon.map[2|3]=
 495                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 496                         support via parallel port (up to 5 devices per port)
 497                         Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 498                         See also Documentation/input/joystick-parport.txt
 499
 500         gamma=          [HW,DRM]
 501
 502         gdth=           [HW,SCSI]
 503                         See header of drivers/scsi/gdth.c.
 504
 505         gpt             [EFI] Forces disk with valid GPT signature but
 506                         invalid Protective MBR to be treated as GPT.
 507
 508         gscd=           [HW,CD]
 509                         Format: <io>
 510
 511         gt96100eth=     [NET] MIPS GT96100 Advanced Communication Controller
 512
 513         gus=            [HW,OSS]
 514                         Format: <io>,<irq>,<dma>,<dma16>
 515
 516         gvp11=          [HW,SCSI]
 517
 518         hashdist=       [KNL,NUMA] Large hashes allocated during boot
 519                         are distributed across NUMA nodes.  Defaults on
 520                         for IA-64, off otherwise.
 521
 522         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 523
 524         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 525                         Format: <cyl>,<head>,<sect>
 526
 527         hd?=            [HW] (E)IDE subsystem
 528         hd?lun=         See Documentation/ide.txt.
 529
 530         highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 531                         size of <nn>. This works even on boxes that have no
 532                         highmem otherwise. This also works to reduce highmem
 533                         size on bigger boxes.
 534
 535         hisax=          [HW,ISDN]
 536                         See Documentation/isdn/README.HiSax.
 537
 538         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 539
 540         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
 541
 542         i8042.direct    [HW] Put keyboard port into non-translated mode
 543         i8042.dumbkbd   [HW] Pretend that controlled can only read data from
 544                              keyboard and can not control its state
 545                              (Don't attempt to blink the leds)
 546         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 547         i8042.nomux     [HW] Don't check presence of an active multiplexing
 548                              controller
 549         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 550                              controllers
 551         i8042.panicblink=
 552                         [HW] Frequency with which keyboard LEDs should blink
 553                              when kernel panics (default is 0.5 sec)
 554         i8042.reset     [HW] Reset the controller during init and cleanup
 555         i8042.unlock    [HW] Unlock (ignore) the keylock
 556
 557         i810=           [HW,DRM]
 558
 559         i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 560                         indicates that the driver is running on unsupported
 561                         hardware.
 562         i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 563                         does not match list of supported models.
 564         i8k.power_status
 565                         [HW] Report power status in /proc/i8k
 566                         (disabled by default)
 567         i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 568                         capability is set.
 569
 570         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 571                         See Documentation/mca.txt.
 572
 573         icn=            [HW,ISDN]
 574                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 575
 576         ide=            [HW] (E)IDE subsystem
 577                         Format: ide=nodma or ide=doubler or ide=reverse
 578                         See Documentation/ide.txt.
 579
 580         ide?=           [HW] (E)IDE subsystem
 581                         Format: ide?=noprobe or chipset specific parameters.
 582                         See Documentation/ide.txt.
 583
 584         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 585                         See Documentation/ide.txt.
 586
 587         idle=           [HW]
 588                         Format: idle=poll or idle=halt
 589
 590         ihash_entries=  [KNL]
 591                         Set number of hash buckets for inode cache.
 592
 593         in2000=         [HW,SCSI]
 594                         See header of drivers/scsi/in2000.c.
 595
 596         init=           [KNL]
 597                         Format: <full_path>
 598                         Run specified binary instead of /sbin/init as init
 599                         process.
 600
 601         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 602                         for working out where the kernel is dying during
 603                         startup.
 604
 605         initrd=         [BOOT] Specify the location of the initial ramdisk
 606
 607         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 608                         Format: <irq>
 609
 610         inttest=        [IA64]
 611
 612         io7=            [HW] IO7 for Marvel based alpha systems
 613                         See comment before marvel_specify_io7 in
 614                         arch/alpha/kernel/core_marvel.c.
 615
 616         ip=             [IP_PNP]
 617                         See Documentation/nfsroot.txt.
 618
 619         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 620                         See comment before ip2_setup() in drivers/char/ip2.c.
 621
 622         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 623                         See header of drivers/scsi/ips.c.
 624
 625         irqfixup        [HW]
 626                         When an interrupt is not handled search all handlers
 627                         for it. Intended to get systems with badly broken
 628                         firmware running.
 629
 630         irqpoll         [HW]
 631                         When an interrupt is not handled search all handlers
 632                         for it. Also check all handlers each timer
 633                         interrupt. Intended to get systems with badly broken
 634                         firmware running.
 635
 636         isapnp=         [ISAPNP]
 637                         Format: <RDP>, <reset>, <pci_scan>, <verbosity>
 638
 639         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 640                         Format: <cpu number>,...,<cpu number>
 641                         This option can be used to specify one or more CPUs
 642                         to isolate from the general SMP balancing and scheduling
 643                         algorithms. The only way to move a process onto or off
 644                         an "isolated" CPU is via the CPU affinity syscalls.
 645                         <cpu number> begins at 0 and the maximum value is
 646                         "number of CPUs in system - 1".
 647
 648                         This option is the preferred way to isolate CPUs. The
 649                         alternative - manually setting the CPU mask of all tasks
 650                         in the system can cause problems and suboptimal load
 651                         balancer performance.
 652
 653         isp16=          [HW,CD]
 654                         Format: <io>,<irq>,<dma>,<setup>
 655
 656         iucv=           [HW,NET]
 657
 658         js=             [HW,JOY] Analog joystick
 659                         See Documentation/input/joystick.txt.
 660
 661         keepinitrd      [HW,ARM]
 662
 663         kstack=N        [IA-32, X86-64] Print N words from the kernel stack
 664                         in oops dumps.
 665
 666         l2cr=           [PPC]
 667
 668         lapic           [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
 669
 670         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 671                         Format: addr:<io>,irq:<irq>
 672
 673         llsc*=          [IA64]
 674                         See function print_params() in arch/ia64/sn/kernel/llsc4.c.
 675
 676         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 677                         See Documentation/ramdisk.txt.
 678
 679         lockd.udpport=  [NFS]
 680
 681         lockd.tcpport=  [NFS]
 682
 683         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 684                         Format: <irq>
 685
 686         loglevel=       All Kernel Messages with a loglevel smaller than the
 687                         console loglevel will be printed to the console. It can
 688                         also be changed with klogd or other programs. The
 689                         loglevels are defined as follows:
 690
 691                         0 (KERN_EMERG)          system is unusable
 692                         1 (KERN_ALERT)          action must be taken immediately
 693                         2 (KERN_CRIT)           critical conditions
 694                         3 (KERN_ERR)            error conditions
 695                         4 (KERN_WARNING)        warning conditions
 696                         5 (KERN_NOTICE)         normal but significant condition
 697                         6 (KERN_INFO)           informational
 698                         7 (KERN_DEBUG)          debug-level messages
 699
 700         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 701                         Format is n, nk, nM.  n must be a power of two.  The
 702                         default is set in kernel config.
 703
 704         lp=0            [LP]    Specify parallel ports to use, e.g,
 705         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 706         lp=reset                first parallel port). 'lp=0' disables the
 707         lp=auto                 printer driver. 'lp=reset' (which can be
 708                                 specified in addition to the ports) causes
 709                                 attached printers to be reset. Using
 710                                 lp=port1,port2,... specifies the parallel ports
 711                                 to associate lp devices with, starting with
 712                                 lp0. A port specification may be 'none' to skip
 713                                 that lp device, or a parport name such as
 714                                 'parport0'. Specifying 'lp=auto' instead of a
 715                                 port specification list means that device IDs
 716                                 from each port should be examined, to see if
 717                                 an IEEE 1284-compliant printer is attached; if
 718                                 so, the driver will manage that printer.
 719                                 See also header of drivers/char/lp.c.
 720
 721         lpj=n           [KNL]
 722                         Sets loops_per_jiffy to given constant, thus avoiding
 723                         time-consuming boot-time autodetection (up to 250 ms per
 724                         CPU). 0 enables autodetection (default). To determine
 725                         the correct value for your kernel, boot with normal
 726                         autodetection and see what value is printed. Note that
 727                         on SMP systems the preset will be applied to all CPUs,
 728                         which is likely to cause problems if your CPUs need
 729                         significantly divergent settings. An incorrect value
 730                         will cause delays in the kernel to be wrong, leading to
 731                         unpredictable I/O errors and other breakage. Although
 732                         unlikely, in the extreme case this might damage your
 733                         hardware.
 734
 735         ltpc=           [NET]
 736                         Format: <io>,<irq>,<dma>
 737
 738         mac5380=        [HW,SCSI]
 739                         Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 740
 741         mac53c9x=       [HW,SCSI]
 742                         Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 743
 744         machvec=        [IA64]
 745                         Force the use of a particular machine-vector (machvec) in a generic
 746                         kernel.  Example: machvec=hpzx1_swiotlb
 747
 748         mad16=          [HW,OSS]
 749                         Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
 750
 751         maui=           [HW,OSS]
 752                         Format: <io>,<irq>
 753
 754         max_loop=       [LOOP] Maximum number of loopback devices that can
 755                         be mounted
 756                         Format: <1-256>
 757
 758         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 759                         should make use of
 760
 761         max_addr=[KMG]  [KNL,BOOT,ia64] All physical memory greater than or
 762                         equal to this physical address is ignored.
 763
 764         max_luns=       [SCSI] Maximum number of LUNs to probe
 765                         Should be between 1 and 2^32-1.
 766
 767         max_report_luns=
 768                         [SCSI] Maximum number of LUNs received
 769                         Should be between 1 and 16384.
 770
 771         mca-pentium     [BUGS=IA-32]
 772
 773         mcatest=        [IA-64]
 774
 775         mcd=            [HW,CD]
 776                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 777
 778         mcdx=           [HW,CD]
 779
 780         mce             [IA-32] Machine Check Exception
 781
 782         md=             [HW] RAID subsystems devices and level
 783                         See Documentation/md.txt.
 784
 785         mdacon=         [MDA]
 786                         Format: <first>,<last>
 787                         Specifies range of consoles to be captured by the MDA.
 788
 789         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 790                         Amount of memory to be used when the kernel is not able
 791                         to see the whole system memory or for test.
 792                         [IA-32] Use together with memmap= to avoid physical
 793                         address space collisions. Without memmap= PCI devices
 794                         could be placed at addresses belonging to unused RAM.
 795
 796         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 797                         memory.
 798
 799         memmap=exactmap [KNL,IA-32] Enable setting of an exact
 800                         E820 memory map, as specified by the user.
 801                         Such memmap=exactmap lines can be constructed based on
 802                         BIOS output or other requirements. See the memmap=nn@ss
 803                         option description.
 804
 805         memmap=nn[KMG]@ss[KMG]
 806                         [KNL] Force usage of a specific region of memory
 807                         Region of memory to be used, from ss to ss+nn.
 808
 809         memmap=nn[KMG]#ss[KMG]
 810                         [KNL,ACPI] Mark specific memory as ACPI data.
 811                         Region of memory to be used, from ss to ss+nn.
 812
 813         memmap=nn[KMG]$ss[KMG]
 814                         [KNL,ACPI] Mark specific memory as reserved.
 815                         Region of memory to be used, from ss to ss+nn.
 816
 817         meye.*=         [HW] Set MotionEye Camera parameters
 818                         See Documentation/video4linux/meye.txt.
 819
 820         mga=            [HW,DRM]
 821
 822         mousedev.tap_time=
 823                         [MOUSE] Maximum time between finger touching and
 824                         leaving touchpad surface for touch to be considered
 825                         a tap and be reported as a left button click (for
 826                         touchpads working in absolute mode only).
 827                         Format: <msecs>
 828         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
 829                         reporting absolute coordinates, such as tablets
 830         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
 831                         reporting absolute coordinates, such as tablets
 832
 833         mpu401=         [HW,OSS]
 834                         Format: <io>,<irq>
 835
 836         MTD_Partition=  [MTD]
 837                         Format: <name>,<region-number>,<size>,<offset>
 838
 839         MTD_Region=     [MTD]
 840                         Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
 841
 842         mtdparts=       [MTD]
 843                         See drivers/mtd/cmdline.c.
 844
 845         mtouchusb.raw_coordinates=
 846                         [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
 847                         or cooked coordinates ('n')
 848
 849         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
 850
 851         NCR_D700=       [HW,SCSI]
 852                         See header of drivers/scsi/NCR_D700.c.
 853
 854         ncr5380=        [HW,SCSI]
 855
 856         ncr53c400=      [HW,SCSI]
 857
 858         ncr53c400a=     [HW,SCSI]
 859
 860         ncr53c406a=     [HW,SCSI]
 861
 862         ncr53c8xx=      [HW,SCSI]
 863
 864         netdev=         [NET] Network devices parameters
 865                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
 866                         Note that mem_start is often overloaded to mean
 867                         something different and driver-specific.
 868
 869         nfsaddrs=       [NFS]
 870                         See Documentation/nfsroot.txt.
 871
 872         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
 873                         See Documentation/nfsroot.txt.
 874
 875         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 876
 877         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
 878                         emulation library even if a 387 maths coprocessor
 879                         is present.
 880
 881         noalign         [KNL,ARM]
 882
 883         noapic          [SMP,APIC] Tells the kernel to not make use of any
 884                         IOAPICs that may be present in the system.
 885
 886         noasync         [HW,M68K] Disables async and sync negotiation for
 887                         all devices.
 888
 889         nobats          [PPC] Do not use BATs for mapping kernel lowmem
 890                         on "Classic" PPC cores.
 891
 892         nocache         [ARM]
 893
 894         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
 895
 896         noexec          [IA-64]
 897
 898         noexec          [IA-32, X86-64]
 899                         noexec=on: enable non-executable mappings (default)
 900                         noexec=off: disable nn-executable mappings
 901
 902         nofxsr          [BUGS=IA-32]
 903
 904         nohlt           [BUGS=ARM]
 905
 906         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
 907                         instruction doesn't work correctly and not to
 908                         use it.
 909
 910         nohalt          [IA-64] Tells the kernel not to use the power saving
 911                         function PAL_HALT_LIGHT when idle. This increases
 912                         power-consumption. On the positive side, it reduces
 913                         interrupt wake-up latency, which may improve performance
 914                         in certain environments such as networked servers or
 915                         real-time systems.
 916
 917         noirqdebug      [IA-32] Disables the code which attempts to detect and
 918                         disable unhandled interrupt sources.
 919
 920         noisapnp        [ISAPNP] Disables ISA PnP code.
 921
 922         noinitrd        [RAM] Tells the kernel not to load any configured
 923                         initial RAM disk.
 924
 925         nointroute      [IA-64]
 926
 927         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 928
 929         noltlbs         [PPC] Do not use large page/tlb entries for kernel
 930                         lowmem mapping on PPC40x.
 931
 932         nomce           [IA-32] Machine Check Exception
 933
 934         noresidual      [PPC] Don't use residual data on PReP machines.
 935
 936         noresume        [SWSUSP] Disables resume and restore original swap space.
 937
 938         no-scroll       [VGA] Disables scrollback.
 939                         This is required for the Braillex ib80-piezo Braille
 940                         reader made by F.H. Papenmeier (Germany).
 941
 942         nosbagart       [IA-64]
 943
 944         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
 945
 946         nosync          [HW,M68K] Disables sync negotiation for all devices.
 947
 948         notsc           [BUGS=IA-32] Disable Time Stamp Counter
 949
 950         nousb           [USB] Disable the USB subsystem
 951
 952         nowb            [ARM]
 953
 954         opl3=           [HW,OSS]
 955                         Format: <io>
 956
 957         opl3sa=         [HW,OSS]
 958                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
 959
 960         opl3sa2=        [HW,OSS]
 961                         Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
 962
 963         oprofile.timer= [HW]
 964                         Use timer interrupt instead of performance counters
 965
 966         optcd=          [HW,CD]
 967                         Format: <io>
 968
 969         osst=           [HW,SCSI] SCSI Tape Driver
 970                         Format: <buffer_size>,<write_threshold>
 971                         See also Documentation/scsi/st.txt.
 972
 973         panic=          [KNL] Kernel behaviour on panic
 974                         Format: <timeout>
 975
 976         parkbd.port=    [HW] Parallel port number the keyboard adapter is
 977                         connected to, default is 0.
 978                         Format: <parport#>
 979         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
 980                         0 for XT, 1 for AT (default is AT).
 981                         Format: <mode>
 982
 983         parport=0       [HW,PPT]        Specify parallel ports. 0 disables.
 984         parport=auto                    Use 'auto' to force the driver to use
 985         parport=0xBBB[,IRQ[,DMA]]       any IRQ/DMA settings detected (the
 986                                         default is to ignore detected IRQ/DMA
 987                                         settings because of possible
 988                                         conflicts). You can specify the base
 989                                         address, IRQ, and DMA settings; IRQ and
 990                                         DMA should be numbers, or 'auto' (for
 991                                         using detected settings on that
 992                                         particular port), or 'nofifo' (to avoid
 993                                         using a FIFO even if it is detected).
 994                                         Parallel ports are assigned in the
 995                                         order they are specified on the command
 996                                         line, starting with parport0.
 997
 998         parport_init_mode=
 999                         [HW,PPT]        Configure VIA parallel port to
1000                                         operate in specific mode. This is
1001                                         necessary on Pegasos computer where
1002                                         firmware has no options for setting up
1003                                         parallel port mode and sets it to
1004                                         spp. Currently this function knows
1005                                         686a and 8231 chips.
1006                         Format: [spp|ps2|epp|ecp|ecpepp]
1007
1008         pas2=           [HW,OSS]
1009                         Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1010
1011         pas16=          [HW,SCSI]
1012                         See header of drivers/scsi/pas16.c.
1013
1014         pcbit=          [HW,ISDN]
1015
1016         pcd.            [PARIDE]
1017                         See header of drivers/block/paride/pcd.c.
1018                         See also Documentation/paride.txt.
1019
1020         pci=option[,option...]          [PCI] various PCI subsystem options:
1021                 off                     [IA-32] don't probe for the PCI bus
1022                 bios                    [IA-32] force use of PCI BIOS, don't access
1023                                         the hardware directly. Use this if your machine
1024                                         has a non-standard PCI host bridge.
1025                 nobios                  [IA-32] disallow use of PCI BIOS, only direct
1026                                         hardware access methods are allowed. Use this
1027                                         if you experience crashes upon bootup and you
1028                                         suspect they are caused by the BIOS.
1029                 conf1                   [IA-32] Force use of PCI Configuration Mechanism 1.
1030                 conf2                   [IA-32] Force use of PCI Configuration Mechanism 2.
1031                 nosort                  [IA-32] Don't sort PCI devices according to
1032                                         order given by the PCI BIOS. This sorting is done
1033                                         to get a device order compatible with older kernels.
1034                 biosirq                 [IA-32] Use PCI BIOS calls to get the interrupt
1035                                         routing table. These calls are known to be buggy
1036                                         on several machines and they hang the machine when used,
1037                                         but on other computers it's the only way to get the
1038                                         interrupt routing table. Try this option if the kernel
1039                                         is unable to allocate IRQs or discover secondary PCI
1040                                         buses on your motherboard.
1041                 rom                     [IA-32] Assign address space to expansion ROMs.
1042                                         Use with caution as certain devices share address
1043                                         decoders between ROMs and other resources.
1044                 irqmask=0xMMMM          [IA-32] Set a bit mask of IRQs allowed to be assigned
1045                                         automatically to PCI devices. You can make the kernel
1046                                         exclude IRQs of your ISA cards this way.
1047                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1048                                         of the PIRQ table (normally generated
1049                                         by the BIOS) if it is outside the
1050                                         F0000h-100000h range.
1051                 lastbus=N               [IA-32] Scan all buses till bus #N. Can be useful
1052                                         if the kernel is unable to find your secondary buses
1053                                         and you want to tell it explicitly which ones they are.
1054                 assign-busses           [IA-32] Always assign all PCI bus
1055                                         numbers ourselves, overriding
1056                                         whatever the firmware may have
1057                                         done.
1058                 usepirqmask             [IA-32] Honor the possible IRQ mask
1059                                         stored in the BIOS $PIR table. This is
1060                                         needed on some systems with broken
1061                                         BIOSes, notably some HP Pavilion N5400
1062                                         and Omnibook XE3 notebooks. This will
1063                                         have no effect if ACPI IRQ routing is
1064                                         enabled.
1065                 noacpi                  [IA-32] Do not use ACPI for IRQ routing
1066                                         or for PCI scanning.
1067                 routeirq                Do IRQ routing for all PCI devices.
1068                                         This is normally done in pci_enable_device(),
1069                                         so this option is a temporary workaround
1070                                         for broken drivers that don't call it.
1071
1072                 firmware                [ARM] Do not re-enumerate the bus but
1073                                         instead just use the configuration
1074                                         from the bootloader. This is currently
1075                                         used on IXP2000 systems where the
1076                                         bus has to be configured a certain way
1077                                         for adjunct CPUs.
1078
1079         pcmv=           [HW,PCMCIA] BadgePAD 4
1080
1081         pd.             [PARIDE]
1082                         See Documentation/paride.txt.
1083
1084         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1085                         boot time.
1086                         Format: { 0 | 1 }
1087                         See arch/parisc/kernel/pdc_chassis.c
1088
1089         pf.             [PARIDE]
1090                         See Documentation/paride.txt.
1091
1092         pg.             [PARIDE]
1093                         See Documentation/paride.txt.
1094
1095         pirq=           [SMP,APIC] Manual mp-table setup
1096                         See Documentation/i386/IO-APIC.txt.
1097
1098         plip=           [PPT,NET] Parallel port network link
1099                         Format: { parport<nr> | timid | 0 }
1100                         See also Documentation/parport.txt.
1101
1102         pnpacpi=        [ACPI]
1103                         { off }
1104
1105         pnpbios=        [ISAPNP]
1106                         { on | off | curr | res | no-curr | no-res }
1107
1108         pnp_reserve_irq=
1109                         [ISAPNP] Exclude IRQs for the autoconfiguration
1110
1111         pnp_reserve_dma=
1112                         [ISAPNP] Exclude DMAs for the autoconfiguration
1113
1114         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1115                         Ranges are in pairs (I/O port base and size).
1116
1117         pnp_reserve_mem=
1118                         [ISAPNP] Exclude memory regions for the autoconfiguration
1119                         Ranges are in pairs (memory base and size).
1120
1121         profile=        [KNL] Enable kernel profiling via /proc/profile
1122                         { schedule | <number> }
1123                         (param: schedule - profile schedule points}
1124                         (param: profile step/bucket size as a power of 2 for
1125                                 statistical time based profiling)
1126
1127         processor.max_cstate=   [HW, ACPI]
1128                         Limit processor to maximum C-state
1129                         max_cstate=9 overrides any DMI blacklist limit.
1130
1131         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1132                         before loading.
1133                         See Documentation/ramdisk.txt.
1134
1135         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1136                         probe for (bare|imps|exps|lifebook|any).
1137         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1138                         per second.
1139         psmouse.resetafter=
1140                         [HW,MOUSE] Try to reset the device after so many bad packets
1141                         (0 = never).
1142         psmouse.resolution=
1143                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1144         psmouse.smartscroll=
1145                         [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1146                         0 = disabled, 1 = enabled (default).
1147
1148         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1149                         Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1150
1151         pt.             [PARIDE]
1152                         See Documentation/paride.txt.
1153
1154         quiet=          [KNL] Disable log messages
1155
1156         r128=           [HW,DRM]
1157
1158         raid=           [HW,RAID]
1159                         See Documentation/md.txt.
1160
1161         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1162                         See Documentation/ramdisk.txt.
1163
1164         ramdisk_blocksize=
1165                         [RAM]
1166                         See Documentation/ramdisk.txt.
1167
1168         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1169                         New name for the ramdisk parameter.
1170                         See Documentation/ramdisk.txt.
1171
1172         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1173                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1174                         See arch/*/kernel/reboot.c.
1175
1176         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1177
1178         resume=         [SWSUSP] Specify the partition device for software suspension
1179
1180         rhash_entries=  [KNL,NET]
1181                         Set number of hash buckets for route cache
1182
1183         riscom8=        [HW,SERIAL]
1184                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1185
1186         ro              [KNL] Mount root device read-only on boot
1187
1188         root=           [KNL] Root filesystem
1189
1190         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1191                         mount the root filesystem
1192
1193         rootflags=      [KNL] Set root filesystem mount option string
1194
1195         rootfstype=     [KNL] Set root filesystem type
1196
1197         rw              [KNL] Mount root device read-write on boot
1198
1199         S               [KNL] Run init in single mode
1200
1201         sa1100ir        [NET]
1202                         See drivers/net/irda/sa1100_ir.c.
1203
1204         sb=             [HW,OSS]
1205                         Format: <io>,<irq>,<dma>,<dma2>
1206
1207         sbni=           [NET] Granch SBNI12 leased line adapter
1208
1209         sbpcd=          [HW,CD] Soundblaster CD adapter
1210                         Format: <io>,<type>
1211                         See a comment before function sbpcd_setup() in
1212                         drivers/cdrom/sbpcd.c.
1213
1214         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1215                         Format: <io>[,<timeout>[,<isapnp>]]
1216
1217         scsi_debug_*=   [SCSI]
1218                         See drivers/scsi/scsi_debug.c.
1219
1220         scsi_default_dev_flags=
1221                         [SCSI] SCSI default device flags
1222                         Format: <integer>
1223
1224         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1225                         Format: <vendor>:<model>:<flags>
1226                         (flags are integer value)
1227
1228         scsi_logging=   [SCSI]
1229
1230         selinux         [SELINUX] Disable or enable SELinux at boot time.
1231                         Format: { "0" | "1" }
1232                         See security/selinux/Kconfig help text.
1233                         0 -- disable.
1234                         1 -- enable.
1235                         Default value is set via kernel config option.
1236                         If enabled at boot time, /selinux/disable can be used
1237                         later to disable prior to initial policy load.
1238
1239         serialnumber    [BUGS=IA-32]
1240
1241         sg_def_reserved_size=
1242                         [SCSI]
1243
1244         sgalaxy=        [HW,OSS]
1245                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1246
1247         shapers=        [NET]
1248                         Maximal number of shapers.
1249
1250         sim710=         [SCSI,HW]
1251                         See header of drivers/scsi/sim710.c.
1252
1253         simeth=         [IA-64]
1254         simscsi=
1255
1256         sjcd=           [HW,CD]
1257                         Format: <io>,<irq>,<dma>
1258                         See header of drivers/cdrom/sjcd.c.
1259
1260         slram=          [HW,MTD]
1261
1262         smart2=         [HW]
1263                         Format: <io1>[,<io2>[,...,<io8>]]
1264
1265         snd-ad1816a=    [HW,ALSA]
1266
1267         snd-ad1848=     [HW,ALSA]
1268
1269         snd-ali5451=    [HW,ALSA]
1270
1271         snd-als100=     [HW,ALSA]
1272
1273         snd-als4000=    [HW,ALSA]
1274
1275         snd-azt2320=    [HW,ALSA]
1276
1277         snd-cmi8330=    [HW,ALSA]
1278
1279         snd-cmipci=     [HW,ALSA]
1280
1281         snd-cs4231=     [HW,ALSA]
1282
1283         snd-cs4232=     [HW,ALSA]
1284
1285         snd-cs4236=     [HW,ALSA]
1286
1287         snd-cs4281=     [HW,ALSA]
1288
1289         snd-cs46xx=     [HW,ALSA]
1290
1291         snd-dt019x=     [HW,ALSA]
1292
1293         snd-dummy=      [HW,ALSA]
1294
1295         snd-emu10k1=    [HW,ALSA]
1296
1297         snd-ens1370=    [HW,ALSA]
1298
1299         snd-ens1371=    [HW,ALSA]
1300
1301         snd-es968=      [HW,ALSA]
1302
1303         snd-es1688=     [HW,ALSA]
1304
1305         snd-es18xx=     [HW,ALSA]
1306
1307         snd-es1938=     [HW,ALSA]
1308
1309         snd-es1968=     [HW,ALSA]
1310
1311         snd-fm801=      [HW,ALSA]
1312
1313         snd-gusclassic= [HW,ALSA]
1314
1315         snd-gusextreme= [HW,ALSA]
1316
1317         snd-gusmax=     [HW,ALSA]
1318
1319         snd-hdsp=       [HW,ALSA]
1320
1321         snd-ice1712=    [HW,ALSA]
1322
1323         snd-intel8x0=   [HW,ALSA]
1324
1325         snd-interwave=  [HW,ALSA]
1326
1327         snd-interwave-stb=
1328                         [HW,ALSA]
1329
1330         snd-korg1212=   [HW,ALSA]
1331
1332         snd-maestro3=   [HW,ALSA]
1333
1334         snd-mpu401=     [HW,ALSA]
1335
1336         snd-mtpav=      [HW,ALSA]
1337
1338         snd-nm256=      [HW,ALSA]
1339
1340         snd-opl3sa2=    [HW,ALSA]
1341
1342         snd-opti92x-ad1848=
1343                         [HW,ALSA]
1344
1345         snd-opti92x-cs4231=
1346                         [HW,ALSA]
1347
1348         snd-opti93x=    [HW,ALSA]
1349
1350         snd-pmac=       [HW,ALSA]
1351
1352         snd-rme32=      [HW,ALSA]
1353
1354         snd-rme96=      [HW,ALSA]
1355
1356         snd-rme9652=    [HW,ALSA]
1357
1358         snd-sb8=        [HW,ALSA]
1359
1360         snd-sb16=       [HW,ALSA]
1361
1362         snd-sbawe=      [HW,ALSA]
1363
1364         snd-serial=     [HW,ALSA]
1365
1366         snd-sgalaxy=    [HW,ALSA]
1367
1368         snd-sonicvibes= [HW,ALSA]
1369
1370         snd-sun-amd7930=
1371                         [HW,ALSA]
1372
1373         snd-sun-cs4231= [HW,ALSA]
1374
1375         snd-trident=    [HW,ALSA]
1376
1377         snd-usb-audio=  [HW,ALSA,USB]
1378
1379         snd-via82xx=    [HW,ALSA]
1380
1381         snd-virmidi=    [HW,ALSA]
1382
1383         snd-wavefront=  [HW,ALSA]
1384
1385         snd-ymfpci=     [HW,ALSA]
1386
1387         sonicvibes=     [HW,OSS]
1388                         Format: <reverb>
1389
1390         sonycd535=      [HW,CD]
1391                         Format: <io>[,<irq>]
1392
1393         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1394                         See Documentation/sonypi.txt
1395
1396         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1397                         See Documentation/specialix.txt.
1398
1399         spia_io_base=   [HW,MTD]
1400         spia_fio_base=
1401         spia_pedr=
1402         spia_peddr=
1403
1404         sscape=         [HW,OSS]
1405                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1406
1407         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1408                         See Documentation/scsi/st.txt.
1409
1410         st0x=           [HW,SCSI]
1411                         See header of drivers/scsi/seagate.c.
1412
1413         sti=            [PARISC,HW]
1414                         Format: <num>
1415                         Set the STI (builtin display/keyboard on the HP-PARISC
1416                         machines) console (graphic card) which should be used
1417                         as the initial boot-console.
1418                         See also comment in drivers/video/console/sticore.c.
1419
1420         sti_font=       [HW]
1421                         See comment in drivers/video/console/sticore.c.
1422
1423         stifb=          [HW]
1424                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1425
1426         stram_swap=     [HW,M68k]
1427
1428         swiotlb=        [IA-64] Number of I/O TLB slabs
1429
1430         switches=       [HW,M68k]
1431
1432         sym53c416=      [HW,SCSI]
1433                         See header of drivers/scsi/sym53c416.c.
1434
1435         t128=           [HW,SCSI]
1436                         See header of drivers/scsi/t128.c.
1437
1438         tdfx=           [HW,DRM]
1439
1440         thash_entries=  [KNL,NET]
1441                         Set number of hash buckets for TCP connection
1442
1443         time            Show timing data prefixed to each printk message line
1444
1445         tipar.timeout=  [HW,PPT]
1446                         Set communications timeout in tenths of a second
1447                         (default 15).
1448
1449         tipar.delay=    [HW,PPT]
1450                         Set inter-bit delay in microseconds (default 10).
1451
1452         tmc8xx=         [HW,SCSI]
1453                         See header of drivers/scsi/seagate.c.
1454
1455         tmscsim=        [HW,SCSI]
1456                         See comment before function dc390_setup() in
1457                         drivers/scsi/tmscsim.c.
1458
1459         tp720=          [HW,PS2]
1460
1461         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1462                         Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1463
1464         tsdev.xres=     [TS] Horizontal screen resolution.
1465         tsdev.yres=     [TS] Vertical screen resolution.
1466
1467         turbografx.map[2|3]=
1468                         [HW,JOY] TurboGraFX parallel port interface
1469                         Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1470                         See also Documentation/input/joystick-parport.txt
1471
1472         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1473                         See header of drivers/scsi/u14-34f.c.
1474
1475         uart401=        [HW,OSS]
1476                         Format: <io>,<irq>
1477
1478         uart6850=       [HW,OSS]
1479                         Format: <io>,<irq>
1480
1481         usb-handoff     [HW] Enable early USB BIOS -> OS handoff
1482
1483         usbhid.mousepoll=
1484                         [USBHID] The interval which mice are to be polled at.
1485
1486         video=          [FB] Frame buffer configuration
1487                         See Documentation/fb/modedb.txt.
1488
1489         vga=            [BOOT,IA-32] Select a particular video mode
1490                         See Documentation/i386/boot.txt and Documentation/svga.txt.
1491                         Use vga=ask for menu.
1492                         This is actually a boot loader parameter; the value is
1493                         passed to the kernel using a special protocol.
1494
1495         vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1496                         size of <nn>. This can be used to increase the
1497                         minimum size (128MB on x86). It can also be used to
1498                         decrease the size and leave more room for directly
1499                         mapped kernel RAM.
1500
1501         vmhalt=         [KNL,S390]
1502
1503         vmpoff=         [KNL,S390]
1504
1505         waveartist=     [HW,OSS]
1506                         Format: <io>,<irq>,<dma>,<dma2>
1507
1508         wd33c93=        [HW,SCSI]
1509                         See header of drivers/scsi/wd33c93.c.
1510
1511         wd7000=         [HW,SCSI]
1512                         See header of drivers/scsi/wd7000.c.
1513
1514         wdt=            [WDT] Watchdog
1515                         See Documentation/watchdog/watchdog.txt.
1516
1517         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1518         xd_geo=         See header of drivers/block/xd.c.
1519
1520         xirc2ps_cs=     [NET,PCMCIA]
1521                         Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1522
1523
1524
1525 Changelog:
1526
1527         The last known update (for 2.4.0) - the changelog was not kept before.
1528         2000-06-??      Mr. Unknown
1529
1530         Update for 2.5.49, description for most of the options introduced,
1531         references to other documentation (C files, READMEs, ..), added S390,
1532         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1533         reformatting.
1534         2002-11-24      Petr Baudis <pasky@ucw.cz>
1535                         Randy Dunlap <randy.dunlap@verizon.net>
1536
1537 TODO:
1538
1539         Add documentation for ALSA options.
1540         Add more DRM drivers.