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 DCHP, 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         isapnp=         [ISAPNP]
 626                         Format: <RDP>, <reset>, <pci_scan>, <verbosity>
 627
 628         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 629                         Format: <cpu number>,...,<cpu number>
 630                         This option can be used to specify one or more CPUs
 631                         to isolate from the general SMP balancing and scheduling
 632                         algorithms. The only way to move a process onto or off
 633                         an "isolated" CPU is via the CPU affinity syscalls.
 634                         <cpu number> begins at 0 and the maximum value is
 635                         "number of CPUs in system - 1".
 636
 637                         This option is the preferred way to isolate CPUs. The
 638                         alternative - manually setting the CPU mask of all tasks
 639                         in the system can cause problems and suboptimal load
 640                         balancer performance.
 641
 642         isp16=          [HW,CD]
 643                         Format: <io>,<irq>,<dma>,<setup>
 644
 645         iucv=           [HW,NET]
 646
 647         js=             [HW,JOY] Analog joystick
 648                         See Documentation/input/joystick.txt.
 649
 650         keepinitrd      [HW,ARM]
 651
 652         kstack=N        [IA-32, X86-64] Print N words from the kernel stack
 653                         in oops dumps.
 654
 655         l2cr=           [PPC]
 656
 657         lapic           [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
 658
 659         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 660                         Format: addr:<io>,irq:<irq>
 661
 662         llsc*=          [IA64]
 663                         See function print_params() in arch/ia64/sn/kernel/llsc4.c.
 664
 665         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 666                         See Documentation/ramdisk.txt.
 667
 668         lockd.udpport=  [NFS]
 669
 670         lockd.tcpport=  [NFS]
 671
 672         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 673                         Format: <irq>
 674
 675         loglevel=       All Kernel Messages with a loglevel smaller than the
 676                         console loglevel will be printed to the console. It can
 677                         also be changed with klogd or other programs. The
 678                         loglevels are defined as follows:
 679
 680                         0 (KERN_EMERG)          system is unusable
 681                         1 (KERN_ALERT)          action must be taken immediately
 682                         2 (KERN_CRIT)           critical conditions
 683                         3 (KERN_ERR)            error conditions
 684                         4 (KERN_WARNING)        warning conditions
 685                         5 (KERN_NOTICE)         normal but significant condition
 686                         6 (KERN_INFO)           informational
 687                         7 (KERN_DEBUG)          debug-level messages
 688
 689         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 690                         Format is n, nk, nM.  n must be a power of two.  The
 691                         default is set in kernel config.
 692
 693         lp=0            [LP]    Specify parallel ports to use, e.g,
 694         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 695         lp=reset                first parallel port). 'lp=0' disables the
 696         lp=auto                 printer driver. 'lp=reset' (which can be
 697                                 specified in addition to the ports) causes
 698                                 attached printers to be reset. Using
 699                                 lp=port1,port2,... specifies the parallel ports
 700                                 to associate lp devices with, starting with
 701                                 lp0. A port specification may be 'none' to skip
 702                                 that lp device, or a parport name such as
 703                                 'parport0'. Specifying 'lp=auto' instead of a
 704                                 port specification list means that device IDs
 705                                 from each port should be examined, to see if
 706                                 an IEEE 1284-compliant printer is attached; if
 707                                 so, the driver will manage that printer.
 708                                 See also header of drivers/char/lp.c.
 709
 710         lpj=n           [KNL]
 711                         Sets loops_per_jiffy to given constant, thus avoiding
 712                         time-consuming boot-time autodetection (up to 250 ms per
 713                         CPU). 0 enables autodetection (default). To determine
 714                         the correct value for your kernel, boot with normal
 715                         autodetection and see what value is printed. Note that
 716                         on SMP systems the preset will be applied to all CPUs,
 717                         which is likely to cause problems if your CPUs need
 718                         significantly divergent settings. An incorrect value
 719                         will cause delays in the kernel to be wrong, leading to
 720                         unpredictable I/O errors and other breakage. Although
 721                         unlikely, in the extreme case this might damage your
 722                         hardware.
 723
 724         ltpc=           [NET]
 725                         Format: <io>,<irq>,<dma>
 726
 727         mac5380=        [HW,SCSI]
 728                         Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 729
 730         mac53c9x=       [HW,SCSI]
 731                         Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 732
 733         machvec=        [IA64]
 734                         Force the use of a particular machine-vector (machvec) in a generic
 735                         kernel.  Example: machvec=hpzx1_swiotlb
 736
 737         mad16=          [HW,OSS]
 738                         Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
 739
 740         maui=           [HW,OSS]
 741                         Format: <io>,<irq>
 742
 743         max_loop=       [LOOP] Maximum number of loopback devices that can
 744                         be mounted
 745                         Format: <1-256>
 746
 747         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 748                         should make use of
 749
 750         max_luns=       [SCSI] Maximum number of LUNs to probe
 751                         Should be between 1 and 2^32-1.
 752
 753         max_report_luns=
 754                         [SCSI] Maximum number of LUNs received
 755                         Should be between 1 and 16384.
 756
 757         mca-pentium     [BUGS=IA-32]
 758
 759         mcatest=        [IA-64]
 760
 761         mcd=            [HW,CD]
 762                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 763
 764         mcdx=           [HW,CD]
 765
 766         mce             [IA-32] Machine Check Exception
 767
 768         md=             [HW] RAID subsystems devices and level
 769                         See Documentation/md.txt.
 770
 771         mdacon=         [MDA]
 772                         Format: <first>,<last>
 773                         Specifies range of consoles to be captured by the MDA.
 774
 775         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 776                         Amount of memory to be used when the kernel is not able
 777                         to see the whole system memory or for test.
 778                         [IA-32] Use together with memmap= to avoid physical
 779                         address space collisions. Without memmap= PCI devices
 780                         could be placed at addresses belonging to unused RAM.
 781
 782         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 783                         memory.
 784
 785         memmap=exactmap [KNL,IA-32] Enable setting of an exact
 786                         E820 memory map, as specified by the user.
 787                         Such memmap=exactmap lines can be constructed based on
 788                         BIOS output or other requirements. See the memmap=nn@ss
 789                         option description.
 790
 791         memmap=nn[KMG]@ss[KMG]
 792                         [KNL] Force usage of a specific region of memory
 793                         Region of memory to be used, from ss to ss+nn.
 794
 795         memmap=nn[KMG]#ss[KMG]
 796                         [KNL,ACPI] Mark specific memory as ACPI data.
 797                         Region of memory to be used, from ss to ss+nn.
 798
 799         memmap=nn[KMG]$ss[KMG]
 800                         [KNL,ACPI] Mark specific memory as reserved.
 801                         Region of memory to be used, from ss to ss+nn.
 802
 803         meye.*=         [HW] Set MotionEye Camera parameters
 804                         See Documentation/video4linux/meye.txt.
 805
 806         mga=            [HW,DRM]
 807
 808         mousedev.tap_time=
 809                         [MOUSE] Maximum time between finger touching and
 810                         leaving touchpad surface for touch to be considered
 811                         a tap and be reported as a left button click (for
 812                         touchpads working in absolute mode only).
 813                         Format: <msecs>
 814         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
 815                         reporting absolute coordinates, such as tablets
 816         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
 817                         reporting absolute coordinates, such as tablets
 818
 819         mpu401=         [HW,OSS]
 820                         Format: <io>,<irq>
 821
 822         MTD_Partition=  [MTD]
 823                         Format: <name>,<region-number>,<size>,<offset>
 824
 825         MTD_Region=     [MTD]
 826                         Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
 827
 828         mtdparts=       [MTD]
 829                         See drivers/mtd/cmdline.c.
 830
 831         mtouchusb.raw_coordinates=
 832                         [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
 833                         or cooked coordinates ('n')
 834
 835         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
 836
 837         NCR_D700=       [HW,SCSI]
 838                         See header of drivers/scsi/NCR_D700.c.
 839
 840         ncr5380=        [HW,SCSI]
 841
 842         ncr53c400=      [HW,SCSI]
 843
 844         ncr53c400a=     [HW,SCSI]
 845
 846         ncr53c406a=     [HW,SCSI]
 847
 848         ncr53c8xx=      [HW,SCSI]
 849
 850         netdev=         [NET] Network devices parameters
 851                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
 852                         Note that mem_start is often overloaded to mean
 853                         something different and driver-specific.
 854
 855         nfsaddrs=       [NFS]
 856                         See Documentation/nfsroot.txt.
 857
 858         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
 859                         See Documentation/nfsroot.txt.
 860
 861         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 862
 863         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
 864                         emulation library even if a 387 maths coprocessor
 865                         is present.
 866
 867         noalign         [KNL,ARM]
 868
 869         noapic          [SMP,APIC] Tells the kernel to not make use of any
 870                         IOAPICs that may be present in the system.
 871
 872         noasync         [HW,M68K] Disables async and sync negotiation for
 873                         all devices.
 874
 875         nobats          [PPC] Do not use BATs for mapping kernel lowmem
 876                         on "Classic" PPC cores.
 877
 878         nocache         [ARM]
 879
 880         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
 881
 882         noexec          [IA-64]
 883
 884         noexec          [IA-32, X86-64]
 885                         noexec=on: enable non-executable mappings (default)
 886                         noexec=off: disable nn-executable mappings
 887
 888         nofxsr          [BUGS=IA-32]
 889
 890         nohlt           [BUGS=ARM]
 891
 892         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
 893                         instruction doesn't work correctly and not to
 894                         use it.
 895
 896         nohalt          [IA-64] Tells the kernel not to use the power saving
 897                         function PAL_HALT_LIGHT when idle. This increases
 898                         power-consumption. On the positive side, it reduces
 899                         interrupt wake-up latency, which may improve performance
 900                         in certain environments such as networked servers or
 901                         real-time systems.
 902
 903         noirqdebug      [IA-32] Disables the code which attempts to detect and
 904                         disable unhandled interrupt sources.
 905
 906         noisapnp        [ISAPNP] Disables ISA PnP code.
 907
 908         noinitrd        [RAM] Tells the kernel not to load any configured
 909                         initial RAM disk.
 910
 911         nointroute      [IA-64]
 912
 913         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 914
 915         noltlbs         [PPC] Do not use large page/tlb entries for kernel
 916                         lowmem mapping on PPC40x.
 917
 918         nomce           [IA-32] Machine Check Exception
 919
 920         noresidual      [PPC] Don't use residual data on PReP machines.
 921
 922         noresume        [SWSUSP] Disables resume and restore original swap space.
 923
 924         no-scroll       [VGA] Disables scrollback.
 925                         This is required for the Braillex ib80-piezo Braille
 926                         reader made by F.H. Papenmeier (Germany).
 927
 928         nosbagart       [IA-64]
 929
 930         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
 931
 932         nosync          [HW,M68K] Disables sync negotiation for all devices.
 933
 934         notsc           [BUGS=IA-32] Disable Time Stamp Counter
 935
 936         nousb           [USB] Disable the USB subsystem
 937
 938         nowb            [ARM]
 939
 940         opl3=           [HW,OSS]
 941                         Format: <io>
 942
 943         opl3sa=         [HW,OSS]
 944                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
 945
 946         opl3sa2=        [HW,OSS]
 947                         Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
 948
 949         oprofile.timer= [HW]
 950                         Use timer interrupt instead of performance counters
 951
 952         optcd=          [HW,CD]
 953                         Format: <io>
 954
 955         osst=           [HW,SCSI] SCSI Tape Driver
 956                         Format: <buffer_size>,<write_threshold>
 957                         See also Documentation/scsi/st.txt.
 958
 959         panic=          [KNL] Kernel behaviour on panic
 960                         Format: <timeout>
 961
 962         parkbd.port=    [HW] Parallel port number the keyboard adapter is
 963                         connected to, default is 0.
 964                         Format: <parport#>
 965         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
 966                         0 for XT, 1 for AT (default is AT).
 967                         Format: <mode>
 968
 969         parport=0       [HW,PPT]        Specify parallel ports. 0 disables.
 970         parport=auto                    Use 'auto' to force the driver to use
 971         parport=0xBBB[,IRQ[,DMA]]       any IRQ/DMA settings detected (the
 972                                         default is to ignore detected IRQ/DMA
 973                                         settings because of possible
 974                                         conflicts). You can specify the base
 975                                         address, IRQ, and DMA settings; IRQ and
 976                                         DMA should be numbers, or 'auto' (for
 977                                         using detected settings on that
 978                                         particular port), or 'nofifo' (to avoid
 979                                         using a FIFO even if it is detected).
 980                                         Parallel ports are assigned in the
 981                                         order they are specified on the command
 982                                         line, starting with parport0.
 983
 984         parport_init_mode=
 985                         [HW,PPT]        Configure VIA parallel port to
 986                                         operate in specific mode. This is
 987                                         necessary on Pegasos computer where
 988                                         firmware has no options for setting up
 989                                         parallel port mode and sets it to
 990                                         spp. Currently this function knows
 991                                         686a and 8231 chips.
 992                         Format: [spp|ps2|epp|ecp|ecpepp]
 993
 994         pas2=           [HW,OSS]
 995                         Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
 996
 997         pas16=          [HW,SCSI]
 998                         See header of drivers/scsi/pas16.c.
 999
1000         pcbit=          [HW,ISDN]
1001
1002         pcd.            [PARIDE]
1003                         See header of drivers/block/paride/pcd.c.
1004                         See also Documentation/paride.txt.
1005
1006         pci=option[,option...]          [PCI] various PCI subsystem options:
1007                 off                     [IA-32] don't probe for the PCI bus
1008                 bios                    [IA-32] force use of PCI BIOS, don't access
1009                                         the hardware directly. Use this if your machine
1010                                         has a non-standard PCI host bridge.
1011                 nobios                  [IA-32] disallow use of PCI BIOS, only direct
1012                                         hardware access methods are allowed. Use this
1013                                         if you experience crashes upon bootup and you
1014                                         suspect they are caused by the BIOS.
1015                 conf1                   [IA-32] Force use of PCI Configuration Mechanism 1.
1016                 conf2                   [IA-32] Force use of PCI Configuration Mechanism 2.
1017                 nosort                  [IA-32] Don't sort PCI devices according to
1018                                         order given by the PCI BIOS. This sorting is done
1019                                         to get a device order compatible with older kernels.
1020                 biosirq                 [IA-32] Use PCI BIOS calls to get the interrupt
1021                                         routing table. These calls are known to be buggy
1022                                         on several machines and they hang the machine when used,
1023                                         but on other computers it's the only way to get the
1024                                         interrupt routing table. Try this option if the kernel
1025                                         is unable to allocate IRQs or discover secondary PCI
1026                                         buses on your motherboard.
1027                 rom                     [IA-32] Assign address space to expansion ROMs.
1028                                         Use with caution as certain devices share address
1029                                         decoders between ROMs and other resources.
1030                 irqmask=0xMMMM          [IA-32] Set a bit mask of IRQs allowed to be assigned
1031                                         automatically to PCI devices. You can make the kernel
1032                                         exclude IRQs of your ISA cards this way.
1033                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1034                                         of the PIRQ table (normally generated
1035                                         by the BIOS) if it is outside the
1036                                         F0000h-100000h range.
1037                 lastbus=N               [IA-32] Scan all buses till bus #N. Can be useful
1038                                         if the kernel is unable to find your secondary buses
1039                                         and you want to tell it explicitly which ones they are.
1040                 assign-busses           [IA-32] Always assign all PCI bus
1041                                         numbers ourselves, overriding
1042                                         whatever the firmware may have
1043                                         done.
1044                 usepirqmask             [IA-32] Honor the possible IRQ mask
1045                                         stored in the BIOS $PIR table. This is
1046                                         needed on some systems with broken
1047                                         BIOSes, notably some HP Pavilion N5400
1048                                         and Omnibook XE3 notebooks. This will
1049                                         have no effect if ACPI IRQ routing is
1050                                         enabled.
1051                 noacpi                  [IA-32] Do not use ACPI for IRQ routing
1052                                         or for PCI scanning.
1053                 routeirq                Do IRQ routing for all PCI devices.
1054                                         This is normally done in pci_enable_device(),
1055                                         so this option is a temporary workaround
1056                                         for broken drivers that don't call it.
1057
1058                 firmware                [ARM] Do not re-enumerate the bus but
1059                                         instead just use the configuration
1060                                         from the bootloader. This is currently
1061                                         used on IXP2000 systems where the
1062                                         bus has to be configured a certain way
1063                                         for adjunct CPUs.
1064
1065         pcmv=           [HW,PCMCIA] BadgePAD 4
1066
1067         pd.             [PARIDE]
1068                         See Documentation/paride.txt.
1069
1070         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1071                         boot time.
1072                         Format: { 0 | 1 }
1073                         See arch/parisc/kernel/pdc_chassis.c
1074
1075         pf.             [PARIDE]
1076                         See Documentation/paride.txt.
1077
1078         pg.             [PARIDE]
1079                         See Documentation/paride.txt.
1080
1081         pirq=           [SMP,APIC] Manual mp-table setup
1082                         See Documentation/i386/IO-APIC.txt.
1083
1084         plip=           [PPT,NET] Parallel port network link
1085                         Format: { parport<nr> | timid | 0 }
1086                         See also Documentation/parport.txt.
1087
1088         pnpacpi=        [ACPI]
1089                         { off }
1090
1091         pnpbios=        [ISAPNP]
1092                         { on | off | curr | res | no-curr | no-res }
1093
1094         pnp_reserve_irq=
1095                         [ISAPNP] Exclude IRQs for the autoconfiguration
1096
1097         pnp_reserve_dma=
1098                         [ISAPNP] Exclude DMAs for the autoconfiguration
1099
1100         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1101                         Ranges are in pairs (I/O port base and size).
1102
1103         pnp_reserve_mem=
1104                         [ISAPNP] Exclude memory regions for the autoconfiguration
1105                         Ranges are in pairs (memory base and size).
1106
1107         profile=        [KNL] Enable kernel profiling via /proc/profile
1108                         { schedule | <number> }
1109                         (param: schedule - profile schedule points}
1110                         (param: profile step/bucket size as a power of 2 for
1111                                 statistical time based profiling)
1112
1113         processor.max_cstate=   [HW, ACPI]
1114                         Limit processor to maximum C-state
1115                         max_cstate=9 overrides any DMI blacklist limit.
1116
1117         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1118                         before loading.
1119                         See Documentation/ramdisk.txt.
1120
1121         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1122                         probe for (bare|imps|exps|lifebook|any).
1123         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1124                         per second.
1125         psmouse.resetafter=
1126                         [HW,MOUSE] Try to reset the device after so many bad packets
1127                         (0 = never).
1128         psmouse.resolution=
1129                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1130         psmouse.smartscroll=
1131                         [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1132                         0 = disabled, 1 = enabled (default).
1133
1134         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1135                         Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1136
1137         pt.             [PARIDE]
1138                         See Documentation/paride.txt.
1139
1140         quiet=          [KNL] Disable log messages
1141
1142         r128=           [HW,DRM]
1143
1144         raid=           [HW,RAID]
1145                         See Documentation/md.txt.
1146
1147         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1148                         See Documentation/ramdisk.txt.
1149
1150         ramdisk_blocksize=
1151                         [RAM]
1152                         See Documentation/ramdisk.txt.
1153
1154         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1155                         New name for the ramdisk parameter.
1156                         See Documentation/ramdisk.txt.
1157
1158         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1159                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1160                         See arch/*/kernel/reboot.c.
1161
1162         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1163
1164         resume=         [SWSUSP] Specify the partition device for software suspension
1165
1166         rhash_entries=  [KNL,NET]
1167                         Set number of hash buckets for route cache
1168
1169         riscom8=        [HW,SERIAL]
1170                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1171
1172         ro              [KNL] Mount root device read-only on boot
1173
1174         root=           [KNL] Root filesystem
1175
1176         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1177                         mount the root filesystem
1178
1179         rootflags=      [KNL] Set root filesystem mount option string
1180
1181         rootfstype=     [KNL] Set root filesystem type
1182
1183         rw              [KNL] Mount root device read-write on boot
1184
1185         S               [KNL] Run init in single mode
1186
1187         sa1100ir        [NET]
1188                         See drivers/net/irda/sa1100_ir.c.
1189
1190         sb=             [HW,OSS]
1191                         Format: <io>,<irq>,<dma>,<dma2>
1192
1193         sbni=           [NET] Granch SBNI12 leased line adapter
1194
1195         sbpcd=          [HW,CD] Soundblaster CD adapter
1196                         Format: <io>,<type>
1197                         See a comment before function sbpcd_setup() in
1198                         drivers/cdrom/sbpcd.c.
1199
1200         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1201                         Format: <io>[,<timeout>[,<isapnp>]]
1202
1203         scsi_debug_*=   [SCSI]
1204                         See drivers/scsi/scsi_debug.c.
1205
1206         scsi_default_dev_flags=
1207                         [SCSI] SCSI default device flags
1208                         Format: <integer>
1209
1210         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1211                         Format: <vendor>:<model>:<flags>
1212                         (flags are integer value)
1213
1214         scsi_logging=   [SCSI]
1215
1216         selinux         [SELINUX] Disable or enable SELinux at boot time.
1217                         Format: { "0" | "1" }
1218                         See security/selinux/Kconfig help text.
1219                         0 -- disable.
1220                         1 -- enable.
1221                         Default value is set via kernel config option.
1222                         If enabled at boot time, /selinux/disable can be used
1223                         later to disable prior to initial policy load.
1224
1225         serialnumber    [BUGS=IA-32]
1226
1227         sg_def_reserved_size=
1228                         [SCSI]
1229
1230         sgalaxy=        [HW,OSS]
1231                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1232
1233         shapers=        [NET]
1234                         Maximal number of shapers.
1235
1236         sim710=         [SCSI,HW]
1237                         See header of drivers/scsi/sim710.c.
1238
1239         simeth=         [IA-64]
1240         simscsi=
1241
1242         sjcd=           [HW,CD]
1243                         Format: <io>,<irq>,<dma>
1244                         See header of drivers/cdrom/sjcd.c.
1245
1246         slram=          [HW,MTD]
1247
1248         smart2=         [HW]
1249                         Format: <io1>[,<io2>[,...,<io8>]]
1250
1251         snd-ad1816a=    [HW,ALSA]
1252
1253         snd-ad1848=     [HW,ALSA]
1254
1255         snd-ali5451=    [HW,ALSA]
1256
1257         snd-als100=     [HW,ALSA]
1258
1259         snd-als4000=    [HW,ALSA]
1260
1261         snd-azt2320=    [HW,ALSA]
1262
1263         snd-cmi8330=    [HW,ALSA]
1264
1265         snd-cmipci=     [HW,ALSA]
1266
1267         snd-cs4231=     [HW,ALSA]
1268
1269         snd-cs4232=     [HW,ALSA]
1270
1271         snd-cs4236=     [HW,ALSA]
1272
1273         snd-cs4281=     [HW,ALSA]
1274
1275         snd-cs46xx=     [HW,ALSA]
1276
1277         snd-dt019x=     [HW,ALSA]
1278
1279         snd-dummy=      [HW,ALSA]
1280
1281         snd-emu10k1=    [HW,ALSA]
1282
1283         snd-ens1370=    [HW,ALSA]
1284
1285         snd-ens1371=    [HW,ALSA]
1286
1287         snd-es968=      [HW,ALSA]
1288
1289         snd-es1688=     [HW,ALSA]
1290
1291         snd-es18xx=     [HW,ALSA]
1292
1293         snd-es1938=     [HW,ALSA]
1294
1295         snd-es1968=     [HW,ALSA]
1296
1297         snd-fm801=      [HW,ALSA]
1298
1299         snd-gusclassic= [HW,ALSA]
1300
1301         snd-gusextreme= [HW,ALSA]
1302
1303         snd-gusmax=     [HW,ALSA]
1304
1305         snd-hdsp=       [HW,ALSA]
1306
1307         snd-ice1712=    [HW,ALSA]
1308
1309         snd-intel8x0=   [HW,ALSA]
1310
1311         snd-interwave=  [HW,ALSA]
1312
1313         snd-interwave-stb=
1314                         [HW,ALSA]
1315
1316         snd-korg1212=   [HW,ALSA]
1317
1318         snd-maestro3=   [HW,ALSA]
1319
1320         snd-mpu401=     [HW,ALSA]
1321
1322         snd-mtpav=      [HW,ALSA]
1323
1324         snd-nm256=      [HW,ALSA]
1325
1326         snd-opl3sa2=    [HW,ALSA]
1327
1328         snd-opti92x-ad1848=
1329                         [HW,ALSA]
1330
1331         snd-opti92x-cs4231=
1332                         [HW,ALSA]
1333
1334         snd-opti93x=    [HW,ALSA]
1335
1336         snd-pmac=       [HW,ALSA]
1337
1338         snd-rme32=      [HW,ALSA]
1339
1340         snd-rme96=      [HW,ALSA]
1341
1342         snd-rme9652=    [HW,ALSA]
1343
1344         snd-sb8=        [HW,ALSA]
1345
1346         snd-sb16=       [HW,ALSA]
1347
1348         snd-sbawe=      [HW,ALSA]
1349
1350         snd-serial=     [HW,ALSA]
1351
1352         snd-sgalaxy=    [HW,ALSA]
1353
1354         snd-sonicvibes= [HW,ALSA]
1355
1356         snd-sun-amd7930=
1357                         [HW,ALSA]
1358
1359         snd-sun-cs4231= [HW,ALSA]
1360
1361         snd-trident=    [HW,ALSA]
1362
1363         snd-usb-audio=  [HW,ALSA,USB]
1364
1365         snd-via82xx=    [HW,ALSA]
1366
1367         snd-virmidi=    [HW,ALSA]
1368
1369         snd-wavefront=  [HW,ALSA]
1370
1371         snd-ymfpci=     [HW,ALSA]
1372
1373         sonicvibes=     [HW,OSS]
1374                         Format: <reverb>
1375
1376         sonycd535=      [HW,CD]
1377                         Format: <io>[,<irq>]
1378
1379         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1380                         See Documentation/sonypi.txt
1381
1382         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1383                         See Documentation/specialix.txt.
1384
1385         spia_io_base=   [HW,MTD]
1386         spia_fio_base=
1387         spia_pedr=
1388         spia_peddr=
1389
1390         sscape=         [HW,OSS]
1391                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1392
1393         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1394                         See Documentation/scsi/st.txt.
1395
1396         st0x=           [HW,SCSI]
1397                         See header of drivers/scsi/seagate.c.
1398
1399         sti=            [PARISC,HW]
1400                         Format: <num>
1401                         Set the STI (builtin display/keyboard on the HP-PARISC
1402                         machines) console (graphic card) which should be used
1403                         as the initial boot-console.
1404                         See also comment in drivers/video/console/sticore.c.
1405
1406         sti_font=       [HW]
1407                         See comment in drivers/video/console/sticore.c.
1408
1409         stifb=          [HW]
1410                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1411
1412         stram_swap=     [HW,M68k]
1413
1414         swiotlb=        [IA-64] Number of I/O TLB slabs
1415
1416         switches=       [HW,M68k]
1417
1418         sym53c416=      [HW,SCSI]
1419                         See header of drivers/scsi/sym53c416.c.
1420
1421         t128=           [HW,SCSI]
1422                         See header of drivers/scsi/t128.c.
1423
1424         tdfx=           [HW,DRM]
1425
1426         thash_entries=  [KNL,NET]
1427                         Set number of hash buckets for TCP connection
1428
1429         time            Show timing data prefixed to each printk message line
1430
1431         tipar.timeout=  [HW,PPT]
1432                         Set communications timeout in tenths of a second
1433                         (default 15).
1434
1435         tipar.delay=    [HW,PPT]
1436                         Set inter-bit delay in microseconds (default 10).
1437
1438         tmc8xx=         [HW,SCSI]
1439                         See header of drivers/scsi/seagate.c.
1440
1441         tmscsim=        [HW,SCSI]
1442                         See comment before function dc390_setup() in
1443                         drivers/scsi/tmscsim.c.
1444
1445         tp720=          [HW,PS2]
1446
1447         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1448                         Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1449
1450         tsdev.xres=     [TS] Horizontal screen resolution.
1451         tsdev.yres=     [TS] Vertical screen resolution.
1452
1453         turbografx.map[2|3]=
1454                         [HW,JOY] TurboGraFX parallel port interface
1455                         Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1456                         See also Documentation/input/joystick-parport.txt
1457
1458         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1459                         See header of drivers/scsi/u14-34f.c.
1460
1461         uart401=        [HW,OSS]
1462                         Format: <io>,<irq>
1463
1464         uart6850=       [HW,OSS]
1465                         Format: <io>,<irq>
1466
1467         usb-handoff     [HW] Enable early USB BIOS -> OS handoff
1468
1469         usbhid.mousepoll=
1470                         [USBHID] The interval which mice are to be polled at.
1471
1472         video=          [FB] Frame buffer configuration
1473                         See Documentation/fb/modedb.txt.
1474
1475         vga=            [BOOT,IA-32] Select a particular video mode
1476                         See Documentation/i386/boot.txt and Documentation/svga.txt.
1477                         Use vga=ask for menu.
1478                         This is actually a boot loader parameter; the value is
1479                         passed to the kernel using a special protocol.
1480
1481         vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1482                         size of <nn>. This can be used to increase the
1483                         minimum size (128MB on x86). It can also be used to
1484                         decrease the size and leave more room for directly
1485                         mapped kernel RAM.
1486
1487         vmhalt=         [KNL,S390]
1488
1489         vmpoff=         [KNL,S390]
1490
1491         waveartist=     [HW,OSS]
1492                         Format: <io>,<irq>,<dma>,<dma2>
1493
1494         wd33c93=        [HW,SCSI]
1495                         See header of drivers/scsi/wd33c93.c.
1496
1497         wd7000=         [HW,SCSI]
1498                         See header of drivers/scsi/wd7000.c.
1499
1500         wdt=            [WDT] Watchdog
1501                         See Documentation/watchdog/watchdog.txt.
1502
1503         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1504         xd_geo=         See header of drivers/block/xd.c.
1505
1506         xirc2ps_cs=     [NET,PCMCIA]
1507                         Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1508
1509
1510
1511 Changelog:
1512
1513         The last known update (for 2.4.0) - the changelog was not kept before.
1514         2000-06-??      Mr. Unknown
1515
1516         Update for 2.5.49, description for most of the options introduced,
1517         references to other documentation (C files, READMEs, ..), added S390,
1518         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1519         reformatting.
1520         2002-11-24      Petr Baudis <pasky@ucw.cz>
1521                         Randy Dunlap <randy.dunlap@verizon.net>
1522
1523 TODO:
1524
1525         Add documentation for ALSA options.
1526         Add more DRM drivers.