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 The text in square brackets at the beginning of the description state the
  10 restrictions on the kernel for the said kernel parameter to be valid. The
  11 restrictions referred to are that the relevant option is valid if:
  12
  13         ACPI    ACPI support is enabled.
  14         ALSA    ALSA sound support is enabled.
  15         APIC    APIC support is enabled.
  16         APM     Advanced Power Management support is enabled.
  17         AX25    Appropriate AX.25 support is enabled.
  18         CD      Appropriate CD support is enabled.
  19         DEVFS   devfs support is enabled.
  20         DRM     Direct Rendering Management support is enabled.
  21         EFI     EFI Partitioning (GPT) is enabled
  22         EIDE    EIDE/ATAPI support is enabled.
  23         FB      The frame buffer device is enabled.
  24         HW      Appropriate hardware is enabled.
  25         IA-32   IA-32 aka i386 architecture is enabled.
  26         IA-64   IA-64 architecture is enabled.
  27         IP_PNP  IP DCHP, BOOTP, or RARP is enabled.
  28         ISAPNP  ISA PnP code is enabled.
  29         ISDN    Appropriate ISDN support is enabled.
  30         JOY     Appropriate joystick support is enabled.
  31         LP      Printer support is enabled.
  32         LOOP    Loopback device support is enabled.
  33         M68k    M68k architecture is enabled.
  34                         These options have more detailed description inside of
  35                         Documentation/m68k/kernel-options.txt.
  36         MCA     MCA bus support is enabled.
  37         MDA     MDA console support is enabled.
  38         MOUSE   Appropriate mouse support is enabled.
  39         MTD     MTD support is nebaled.
  40         NET     Appropriate network support is enabled.
  41         NFS     Appropriate NFS support is enabled.
  42         OSS     OSS sound support is enabled.
  43         PARIDE  The ParIDE subsystem is enabled.
  44         PCI     PCI bus support is enabled.
  45         PCMCIA  The PCMCIA subsystem is enabled.
  46         PNP     Plug & Play support is enabled.
  47         PPC     PowerPC architecture is enabled.
  48         PPT     Parallel port support is enabled.
  49         PS2     Appropriate PS/2 support is enabled.
  50         RAM     RAM disk support is enabled.
  51         S390    S390 architecture is enabled.
  52         SCSI    Appropriate SCSI support is enabled.
  53                         A lot of drivers has their options described inside of
  54                         Documentation/scsi/.
  55         SERIAL  Serial support is enabled.
  56         SMP     The kernel is an SMP kernel.
  57         SPARC   Sparc architecture is enabled.
  58         SWSUSP  Software suspension is enabled.
  59         USB     USB support is enabled.
  60         V4L     Video For Linux support is enabled.
  61         VGA     The VGA console has been enabled.
  62         VT      Virtual terminal support is enabled.
  63         WDT     Watchdog support is enabled.
  64         XT      IBM PC/XT MFM hard disk support is enabled.
  65
  66 In addition, the following text indicates that the option:
  67
  68         BUGS=   Relates to possible processor bugs on the said processor.
  69         KNL     Is a kernel start-up parameter.
  70         BOOT    Is a boot loader parameter.
  71
  72 Parameters denoted with BOOT are actually interpreted by the boot
  73 loader, and have no meaning to the kernel directly.
  74 Do not modify the syntax of boot loader parameters without extreme
  75 need or coordination with <Documentation/i386/boot.txt>.
  76
  77 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  78 a trailing = on the name of any parameter states that that parameter will
  79 be entered as an environment variable, whereas its absence indicates that
  80 it will appear as a kernel argument readable via /proc/cmdline by programs
  81 running once the system is up.
  82
  83         53c7xx=         [HW,SCSI] Amiga SCSI controllers
  84                         See header of drivers/scsi/53c7xx.c.
  85                         See also Documentation/scsi/ncr53c7xx.txt.
  86
  87         acpi=           [HW,ACPI] Advanced Configuration and Power Interface
  88                         Format: off[,<...>]
  89                         See also Documentation/pm.txt.
  90
  91         ad1816=         [HW,OSS]
  92                         Format: <io>,<irq>,<dma>,<dma2>
  93                         See also Documentation/sound/oss/AD1816.
  94
  95         ad1848=         [HW,OSS]
  96                         Format: <io>,<irq>,<dma>,<dma2>,<type>
  97
  98         adlib=          [HW,OSS]
  99                         Format: <io>
 100
 101         advansys=       [HW,SCSI]
 102                         See header of drivers/scsi/advansys.c.
 103
 104         advwdt=         [HW,WDT] Advantech WDT
 105                         Format: <iostart>,<iostop>
 106
 107         aedsp16=        [HW,OSS] Audio Excel DSP 16
 108                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 109                         See also header of sound/oss/aedsp16.c.
 110
 111         aha152x=        [HW,SCSI]
 112                         See Documentation/scsi/aha152x.txt.
 113
 114         aha1542=        [HW,SCSI]
 115                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 116
 117         aic7xxx=        [HW,SCSI]
 118                         See Documentation/scsi/aic7xxx.txt.
 119
 120         aic79xx=        [HW,SCSI]
 121                         See Documentation/scsi/aic79xx.txt.
 122
 123         allowdma0       [ISAPNP]
 124
 125         AM53C974=       [HW,SCSI]
 126                         Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
 127                         See also header of drivers/scsi/AM53C974.c.
 128
 129         amijoy=         [HW,JOY] Amiga joystick support
 130
 131         apc=            [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
 132                         Format: noidle
 133                         Disable APC CPU standby support. SPARCstation-Fox does
 134                         not play well with APC CPU idle - disable it if you have
 135                         APC and your system crashes randomly.
 136
 137         apm=            [APM] Advanced Power Management
 138                         See header of arch/i386/kernel/apm.c.
 139
 140         applicom=       [HW]
 141                         Format: <mem>,<irq>
 142
 143         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 144                         Format: <io>,<irq>,<nodeID>
 145
 146         ataflop=        [HW,M68k]
 147
 148         atarimouse=     [HW,MOUSE] Atari Mouse
 149
 150         atascsi=        [HW,SCSI] Atari SCSI
 151
 152         atkbd_set=      [HW] Select keyboard code set
 153                         Format: <int>
 154
 155         atkbd_reset     [HW] Reset keyboard during initialization
 156
 157         autotest        [IA64]
 158
 159         awe=            [HW,OSS] AWE32/SB32/AWE64 wave table synth
 160                         Format: <io>,<memsize>,<isapnp>
 161
 162         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 163                         Format: <io>,0x79 (?)
 164
 165         baycom_epp=     [HW,AX25]
 166                         Format: <io>,<mode>
 167
 168         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 169                         Format: <io>,<mode>
 170                         See header of drivers/net/hamradio/baycom_par.c.
 171
 172         baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 173                         Format: <io>,<irq>,<mode>[,<baud>]
 174                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 175
 176         baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 177                         Format: <io>,<irq>,<mode>
 178                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 179
 180         blkmtd_device=  [HW,MTD]
 181         blkmtd_erasesz=
 182         blkmtd_ro=
 183         blkmtd_bs=
 184         blkmtd_count=
 185
 186         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 187         bttv.radio=     Most important insmod options are available as kernel args too.
 188         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 189         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 190
 191         BusLogic=       [HW,SCSI]
 192                         See drivers/scsi/BusLogic.c, comment before function
 193                         BusLogic_ParseDriverOptions().
 194
 195         c101=           [NET] Moxa C101 synchronous serial card
 196
 197         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 198                         Sometimes CPU hardware bugs make them report the cache
 199                         size incorrectly. The kernel will attempt work arounds
 200                         to fix known problems, but for some CPUs it is not
 201                         possible to determine what the correct size should be.
 202                         This option provides an override for these situations.
 203
 204         cdu31a=         [HW,CD]
 205                         Format: <io>,<irq>[,PAS]
 206                         See header of drivers/cdrom/cdu31a.c.
 207
 208         chandev=        [HW,NET] Generic channel device initialisation
 209
 210         clock=          [BUGS=IA-32, HW] gettimeofday timesource override.
 211                         Forces specified timesource (if avaliable) to be used
 212                         when calculating gettimeofday(). If specicified timesource
 213                         is not avalible, it defaults to PIT.
 214                         Format: { pit | tsc | cyclone | ... }
 215
 216         cm206=          [HW,CD]
 217                         Format: { auto | [<io>,][<irq>] }
 218
 219         com20020=       [HW,NET] ARCnet - COM20020 chipset
 220                         Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 221
 222         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 223                         Format: <io>[,<irq>]
 224
 225         com90xx=        [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
 226                         Format: <io>[,<irq>[,<memstart>]]
 227
 228         condev=         [HW,S390] console device
 229         conmode=
 230
 231         console=        [KNL] Output console
 232                         Console device and comm spec (speed, control, parity).
 233
 234         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 235                         Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 236
 237         cpia_pp=        [HW,PPT]
 238                         Format: { parport<nr> | auto | none }
 239
 240         cs4232=         [HW,OSS]
 241                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 242
 243         cs89x0_dma=     [HW,NET]
 244                         Format: <dma>
 245
 246         cs89x0_media=   [HW,NET]
 247                         Format: { rj45 | aui | bnc }
 248
 249         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 250
 251         dasd=           [HW,NET]
 252                         See header of drivers/s390/block/dasd_devmap.c.
 253
 254         db9=            [HW,JOY]
 255         db9_2=
 256         db9_3=
 257
 258         debug           [KNL] Enable kernel debugging (events log level).
 259
 260         decnet=         [HW,NET]
 261                         Format: <area>[,<node>]
 262                         See also Documentation/networking/decnet.txt.
 263
 264         devfs=          [DEVFS]
 265                         See Documentation/filesystems/devfs/boot-options.
 266
 267         digi=           [HW,SERIAL]
 268                         IO parameters + enable/disable command.
 269
 270         digiepca=       [HW,SERIAL]
 271                         See drivers/char/README.epca and
 272                         Documentation/digiepca.txt.
 273
 274         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 275                         support available.
 276                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 277
 278         dmasound=       [HW,OSS] Sound subsystem buffers
 279
 280         dscc4.setup=    [NET]
 281
 282         dtc3181e=       [HW,SCSI]
 283
 284         eata=           [HW,SCSI]
 285
 286         eda=            [HW,PS2]
 287
 288         edb=            [HW,PS2]
 289
 290         eicon=          [HW,ISDN]
 291                         Format: <id>,<membase>,<irq>
 292
 293         eisa_irq_edge=  [PARISC]
 294                         See header of drivers/parisc/eisa.c.
 295
 296         elanfreq=       [IA-32]
 297                         See comment before function elanfreq_setup() in
 298                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 299
 300         es1370=         [HW,OSS]
 301                         Format: <lineout>[,<micbias>]
 302                         See also header of sound/oss/es1370.c.
 303
 304         es1371=         [HW,OSS]
 305                         Format: <spdif>,[<nomix>,[<amplifier>]]
 306                         See also header of sound/oss/es1371.c.
 307
 308         ether=          [HW,NET] Ethernet cards parameters
 309                         This option is obsoleted by the "netdev=" option, which
 310                         has equivalent usage. See its documentation for details.
 311
 312         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 313                         Format: <io>[,<irq>]
 314
 315         fd_mcs=         [HW,SCSI]
 316                         See header of drivers/scsi/fd_mcs.c.
 317
 318         fdomain=        [HW,SCSI]
 319                         See header of drivers/scsi/fdomain.c.
 320
 321         floppy=         [HW]
 322                         See Documentation/floppy.txt.
 323
 324         ftape=          [HW] Floppy Tape subsystem debugging options.
 325                         See Documentation/ftape.txt.
 326
 327         gamma=          [HW,DRM]
 328
 329         gc=             [HW,JOY]
 330         gc_2=           See Documentation/input/joystick-parport.txt.
 331         gc_3=
 332
 333         gdth=           [HW,SCSI]
 334                         See header of drivers/scsi/gdth.c.
 335
 336         gpt             [EFI] Forces disk with valid GPT signature but
 337                         invalid Protective MBR to be treated as GPT.
 338
 339         gscd=           [HW,CD]
 340                         Format: <io>
 341
 342         gt96100eth=     [NET] MIPS GT96100 Advanced Communication Controller
 343
 344         gus=            [HW,OSS]
 345                         Format: <io>,<irq>,<dma>,<dma16>
 346
 347         gvp11=          [HW,SCSI]
 348
 349         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 350
 351         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 352                         Format: <cyl>,<head>,<sect>
 353
 354         hd?=            [HW] (E)IDE subsystem
 355         hd?lun=         See Documentation/ide.txt.
 356
 357         hisax=          [HW,ISDN]
 358                         See Documentation/isdn/README.HiSax.
 359
 360         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 361
 362         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
 363
 364         i8042_direct    [HW] Keyboard has been put into non-translated mode
 365                         by BIOS
 366         i8042_dumbkbd   [HW] Don't attempt to blink the leds
 367         i8042_noaux     [HW] Don't check for auxiliary (== mouse) port
 368         i8042_nomux
 369         i8042_reset     [HW] Reset the controller during init and cleanup
 370         i8042_unlock    [HW] Unlock (ignore) the keylock
 371
 372         i810=           [HW,DRM]
 373
 374         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 375                         See Documentation/mca.txt.
 376
 377         icn=            [HW,ISDN]
 378                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 379
 380         ide?=           [HW] (E)IDE subsystem
 381                         Config (iomem/irq), tuning or debugging
 382                         (serialize,reset,no{dma,tune,probe}) or chipset
 383                         specific parameters.
 384                         See Documentation/ide.txt.
 385
 386         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 387                         See Documentation/ide.txt.
 388
 389         idle=           [HW]
 390                         Format: poll
 391
 392         in2000=         [HW,SCSI]
 393                         See header of drivers/scsi/in2000.c.
 394
 395         init=           [KNL]
 396                         Format: <full_path>
 397                         Run specified binary instead of /sbin/init as init
 398                         process.
 399
 400         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 401                         for working out where the kernel is dying during
 402                         startup.
 403
 404         initrd=         [BOOT] Specify the location of the initial ramdisk
 405
 406         inport_irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 407                         Format: <irq>
 408
 409         inttest=        [IA64]
 410
 411         io7=            [HW] IO7 for Marvel based alpha systems
 412                         See comment before marvel_specify_io7 in
 413                         arch/alpha/kernel/core_marvel.c.
 414
 415         ip=             [IP_PNP]
 416                         See Documentation/nfsroot.txt.
 417
 418         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 419                         See comment before ip2_setup() in drivers/char/ip2.c.
 420
 421         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 422                         See header of drivers/scsi/ips.c.
 423
 424         isapnp=         [ISAPNP]
 425                         Format: <RDP>, <reset>, <pci_scan>, <verbosity>
 426
 427         isp16=          [HW,CD]
 428                         Format: <io>,<irq>,<dma>,<setup>
 429
 430         iucv=           [HW,NET]
 431
 432         js=             [HW,JOY] Analog joystick
 433                         See Documentation/input/joystick.txt.
 434
 435         keepinitrd      [HW,ARM]
 436
 437         l2cr=           [PPC]
 438
 439         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 440                         Format: addr:<io>,irq:<irq>
 441
 442         llsc*=          [IA64]
 443                         See function print_params() in arch/ia64/sn/kernel/llsc4.c.
 444
 445         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 446                         See Documentation/ramdisk.txt.
 447
 448         lockd.udpport=  [NFS]
 449
 450         lockd.tcpport=  [NFS]
 451
 452         logibm_irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 453                         Format: <irq>
 454
 455         lp=0            [LP]    Specify parallel ports to use, e.g,
 456         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 457         lp=reset                first parallel port). 'lp=0' disables the
 458         lp=auto                 printer driver. 'lp=reset' (which can be
 459                                 specified in addition to the ports) causes
 460                                 attached printers to be reset. Using
 461                                 lp=port1,port2,... specifies the parallel ports
 462                                 to associate lp devices with, starting with
 463                                 lp0. A port specification may be 'none' to skip
 464                                 that lp device, or a parport name such as
 465                                 'parport0'. Specifying 'lp=auto' instead of a
 466                                 port specification list means that device IDs
 467                                 from each port should be examined, to see if
 468                                 an IEEE 1284-compliant printer is attached; if
 469                                 so, the driver will manage that printer.
 470                                 See also header of drivers/char/lp.c.
 471
 472         ltpc=           [NET]
 473                         Format: <io>,<irq>,<dma>
 474
 475         mac5380=        [HW,SCSI]
 476                         Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 477
 478         mac53c9x=       [HW,SCSI]
 479                         Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 480
 481         mad16=          [HW,OSS]
 482                         Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
 483
 484         maui=           [HW,OSS]
 485                         Format: <io>,<irq>
 486
 487         max_loop=       [LOOP] Maximum number of loopback devices that can
 488                         be mounted
 489                         Format: <1-256>
 490
 491         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 492                         should make use of
 493
 494         max_scsi_luns=  [SCSI]
 495
 496         max_scsi_report_luns=
 497                         [SCSI] Maximum number of LUNs received
 498                         Should be between 1 and 16384.
 499
 500         mca-pentium     [BUGS=IA-32]
 501
 502         mcatest=        [IA-64]
 503
 504         mcd=            [HW,CD]
 505                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 506
 507         mcdx=           [HW,CD]
 508
 509         mce             [IA-32] Machine Check Exception
 510
 511         md=             [HW] RAID subsystems devices and level
 512                         See Documentation/md.txt.
 513
 514         mdacon=         [MDA]
 515                         Format: <first>,<last>
 516                         Specifies range of consoles to be captured by the MDA.
 517
 518         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 519                         Amount of memory to be used when the kernel is not able
 520                         to see the whole system memory or for test.
 521
 522         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 523                         memory.
 524
 525         memmap=exactmap [KNL,IA-32] Enable setting of an exact
 526                         E820 memory map, as specified by the user.
 527                         Such memmap=exactmap lines can be constructed based on
 528                         BIOS output or other requirements. See the memmap=nn@ss
 529                         option description.
 530
 531         memmap=nn[KMG]@ss[KMG]
 532                         [KNL] Force usage of a specific region of memory
 533                         Region of memory to be used, from ss to ss+nn.
 534
 535         memmap=nn[KMG]#ss[KMG]
 536                         [KNL,ACPI] Mark specific memory as ACPI data.
 537                         Region of memory to be used, from ss to ss+nn.
 538
 539         memmap=nn[KMG]$ss[KMG]
 540                         [KNL,ACPI] Mark specific memory as reserved.
 541                         Region of memory to be used, from ss to ss+nn.
 542
 543         meye=           [HW] Set MotionEye Camera parameters
 544                         See Documentation/video4linux/meye.txt.
 545
 546         mga=            [HW,DRM]
 547
 548         mpu401=         [HW,OSS]
 549                         Format: <io>,<irq>
 550
 551         MTD_Partition=  [MTD]
 552                         Format: <name>,<region-number>,<size>,<offset>
 553
 554         MTD_Region=     [MTD]
 555                         Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
 556
 557         mtdparts=       [MTD]
 558                         See drivers/mtd/cmdline.c.
 559
 560         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
 561
 562         NCR_D700=       [HW,SCSI]
 563                         See header of drivers/scsi/NCR_D700.c.
 564
 565         ncr5380=        [HW,SCSI]
 566
 567         ncr53c400=      [HW,SCSI]
 568
 569         ncr53c400a=     [HW,SCSI]
 570
 571         ncr53c406a=     [HW,SCSI]
 572
 573         ncr53c8xx=      [HW,SCSI]
 574
 575         netdev=         [NET] Network devices parameters
 576                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
 577                         Note that mem_start is often overloaded to mean
 578                         something different and driver-specific.
 579
 580         nfsaddrs=       [NFS]
 581                         See Documentation/nfsroot.txt.
 582
 583         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
 584                         See Documentation/nfsroot.txt.
 585
 586         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 587
 588         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
 589                         emulation library even if a 387 maths coprocessor
 590                         is present.
 591
 592         noalign         [KNL,ARM]
 593
 594         noapic          [SMP,APIC] Tells the kernel not to make use of any
 595                         APIC that may be present on the system.
 596
 597         noasync         [HW,M68K] Disables async and sync negotiation for
 598                         all devices.
 599
 600         nocache         [ARM]
 601
 602         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
 603
 604         noexec          [IA-64]
 605
 606         nofxsr          [BUGS=IA-32]
 607
 608         nohighio        [BUGS=IA-32] Disable highmem block I/O.
 609
 610         nohlt           [BUGS=ARM]
 611
 612         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
 613                         instruction doesn't work correctly and not to
 614                         use it.
 615
 616         noht            [SMP,IA-32] Disables P4 Xeon(tm) HyperThreading.
 617
 618         noirqdebug      [IA-32] Disables the code which attempts to detect and
 619                         disable unhandled interrupt sources.
 620
 621         noisapnp        [ISAPNP] Disables ISA PnP code.
 622
 623         noinitrd        [RAM] Tells the kernel not to load any configured
 624                         initial RAM disk.
 625
 626         nointroute      [IA-64]
 627
 628         nomce           [IA-32] Machine Check Exception
 629
 630         noresume        [SWSUSP] Disables resume and restore original swap space.
 631
 632         no-scroll       [VGA] Disables scrollback.
 633                         This is required for the Braillex ib80-piezo Braille
 634                         reader made by F.H. Papenmeier (Germany).
 635
 636         nosbagart       [IA-64]
 637
 638         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
 639
 640         nosync          [HW,M68K] Disables sync negotiation for all devices.
 641
 642         notsc           [BUGS=IA-32] Disable Time Stamp Counter
 643
 644         nousb           [USB] Disable the USB subsystem
 645
 646         nowb            [ARM]
 647
 648         opl3=           [HW,OSS]
 649                         Format: <io>
 650
 651         opl3sa=         [HW,OSS]
 652                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
 653
 654         opl3sa2=        [HW,OSS]
 655                         Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
 656
 657         oprofile.timer= [HW]
 658                         Use timer interrupt instead of performance counters
 659
 660         optcd=          [HW,CD]
 661                         Format: <io>
 662
 663         osst=           [HW,SCSI] SCSI Tape Driver
 664                         Format: <buffer_size>,<write_threshold>
 665                         See also Documentation/scsi/st.txt.
 666
 667         panic=          [KNL] Kernel behaviour on panic
 668                         Format: <timeout>
 669
 670         parport=0       [HW,PPT]        Specify parallel ports. 0 disables.
 671         parport=auto                    Use 'auto' to force the driver to use
 672         parport=0xBBB[,IRQ[,DMA]]       any IRQ/DMA settings detected (the
 673                                         default is to ignore detected IRQ/DMA
 674                                         settings because of possible
 675                                         conflicts). You can specify the base
 676                                         address, IRQ, and DMA settings; IRQ and
 677                                         DMA should be numbers, or 'auto' (for
 678                                         using detected settings on that
 679                                         particular port), or 'nofifo' (to avoid
 680                                         using a FIFO even if it is detected).
 681                                         Parallel ports are assigned in the
 682                                         order they are specified on the command
 683                                         line, starting with parport0.
 684
 685         pas2=           [HW,OSS]
 686                         Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
 687
 688         pas16=          [HW,SCSI]
 689                         See header of drivers/scsi/pas16.c.
 690
 691         pcbit=          [HW,ISDN]
 692
 693         pcd.            [PARIDE]
 694                         See header of drivers/block/paride/pcd.c.
 695                         See also Documentation/paride.txt.
 696
 697         pci=option[,option...]          [PCI] various PCI subsystem options:
 698                 off                     [IA-32] don't probe for the PCI bus
 699                 bios                    [IA-32] force use of PCI BIOS, don't access
 700                                         the hardware directly. Use this if your machine
 701                                         has a non-standard PCI host bridge.
 702                 nobios                  [IA-32] disallow use of PCI BIOS, only direct
 703                                         hardware access methods are allowed. Use this
 704                                         if you experience crashes upon bootup and you
 705                                         suspect they are caused by the BIOS.
 706                 conf1                   [IA-32] Force use of PCI Configuration Mechanism 1.
 707                 conf2                   [IA-32] Force use of PCI Configuration Mechanism 2.
 708                 nosort                  [IA-32] Don't sort PCI devices according to
 709                                         order given by the PCI BIOS. This sorting is done
 710                                         to get a device order compatible with older kernels.
 711                 biosirq                 [IA-32] Use PCI BIOS calls to get the interrupt
 712                                         routing table. These calls are known to be buggy
 713                                         on several machines and they hang the machine when used,
 714                                         but on other computers it's the only way to get the
 715                                         interrupt routing table. Try this option if the kernel
 716                                         is unable to allocate IRQs or discover secondary PCI
 717                                         buses on your motherboard.
 718                 rom                     [IA-32] Assign address space to expansion ROMs.
 719                                         Use with caution as certain devices share address
 720                                         decoders between ROMs and other resources.
 721                 irqmask=0xMMMM          [IA-32] Set a bit mask of IRQs allowed to be assigned
 722                                         automatically to PCI devices. You can make the kernel
 723                                         exclude IRQs of your ISA cards this way.
 724                 lastbus=N               [IA-32] Scan all buses till bus #N. Can be useful
 725                                         if the kernel is unable to find your secondary buses
 726                                         and you want to tell it explicitly which ones they are.
 727                 assign-busses           [IA-32] Always assign all PCI bus
 728                                         numbers ourselves, overriding
 729                                         whatever the firmware may have
 730                                         done.
 731                 usepirqmask             [IA-32] Honor the possible IRQ mask
 732                                         stored in the BIOS $PIR table. This is
 733                                         needed on some systems with broken
 734                                         BIOSes, notably some HP Pavilion N5400
 735                                         and Omnibook XE3 notebooks. This will
 736                                         have no effect if ACPI IRQ routing is
 737                                         enabled.
 738                 noacpi                  [IA-32] Do not use ACPI for IRQ routing.
 739
 740         pcmv=           [HW,PCMCIA] BadgePAD 4
 741
 742         pd.             [PARIDE]
 743                         See Documentation/paride.txt.
 744
 745         pf.             [PARIDE]
 746                         See Documentation/paride.txt.
 747
 748         pg.             [PARIDE]
 749                         See Documentation/paride.txt.
 750
 751         pirq=           [SMP,APIC] Manual mp-table setup
 752                         See Documentation/i386/IO-APIC.txt.
 753
 754         plip=           [PPT,NET] Parallel port network link
 755                         Format: { parport<nr> | timid | 0 }
 756                         See also Documentation/parport.txt.
 757
 758         pnpbios=        [ISAPNP]
 759                         { on | off | curr | res | no-curr | no-res }
 760
 761         pnp_reserve_irq=
 762                         [ISAPNP] Exclude IRQs for the autoconfiguration
 763
 764         pnp_reserve_dma=
 765                         [ISAPNP] Exclude DMAs for the autoconfiguration
 766
 767         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
 768                         Ranges are in pairs (I/O port base and size).
 769
 770         pnp_reserve_mem=
 771                         [ISAPNP] Exclude memory regions for the autoconfiguration
 772                         Ranges are in pairs (memory base and size).
 773
 774         profile=        [KNL] Enable kernel profiling via /proc/profile
 775                         (param: profile step/bucket size as a power of 2)
 776
 777         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
 778                         before loading.
 779                         See Documentation/ramdisk.txt.
 780
 781         psmouse_noext   [HW,MOUSE] Disable probing for PS2 mouse protocol extensions
 782
 783         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
 784                         Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
 785
 786         pt.             [PARIDE]
 787                         See Documentation/paride.txt.
 788
 789         quiet=          [KNL] Disable log messages
 790
 791         r128=           [HW,DRM]
 792
 793         raid=           [HW,RAID]
 794                         See Documentation/md.txt.
 795
 796         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
 797                         See Documentation/ramdisk.txt.
 798
 799         ramdisk_blocksize=
 800                         [RAM]
 801                         See Documentation/ramdisk.txt.
 802
 803         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
 804                         New name for the ramdisk parameter.
 805                         See Documentation/ramdisk.txt.
 806
 807         ramdisk_start=  [RAM] Starting block of RAM disk image (so you can
 808                         place it after the kernel image on a boot floppy).
 809                         See Documentation/ramdisk.txt.
 810
 811         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
 812                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
 813                         See arch/*/kernel/reboot.c.
 814
 815         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
 816
 817         resume=         [SWSUSP] Specify the partition device for software suspension
 818
 819         riscom8=        [HW,SERIAL]
 820                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
 821
 822         ro              [KNL] Mount root device read-only on boot
 823
 824         root=           [KNL] Root filesystem
 825
 826         rootflags=      [KNL] Set root filesystem mount option string
 827
 828         rootfstype=     [KNL] Set root filesystem type
 829
 830         rw              [KNL] Mount root device read-write on boot
 831
 832         S               [KNL] Run init in single mode
 833
 834         sa1100ir        [NET]
 835                         See drivers/net/irda/sa1100_ir.c.
 836
 837         sb=             [HW,OSS]
 838                         Format: <io>,<irq>,<dma>,<dma2>
 839
 840         sbni=           [NET] Granch SBNI12 leased line adapter
 841
 842         sbpcd=          [HW,CD] Soundblaster CD adapter
 843                         Format: <io>,<type>
 844                         See a comment before function sbpcd_setup() in
 845                         drivers/cdrom/sbpcd.c.
 846
 847         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
 848                         Format: <io>[,<timeout>[,<isapnp>]]
 849
 850         scsi_debug_*=   [SCSI]
 851                         See drivers/scsi/scsi_debug.c.
 852
 853         scsi_default_dev_flags=
 854                         [SCSI] SCSI default device flags
 855                         Format: <integer>
 856
 857         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
 858                         Format: <vendor>:<model>:<flags>
 859                         (flags are integer value)
 860
 861         scsi_logging=   [SCSI]
 862
 863         scsihosts=      [SCSI]
 864
 865         serialnumber    [BUGS=IA-32]
 866
 867         sf16fm=         [HW] SF16FMI radio driver for Linux
 868                         Format: <io>
 869
 870         sg_def_reserved_size=
 871                         [SCSI]
 872
 873         sgalaxy=        [HW,OSS]
 874                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
 875
 876         shapers=        [NET]
 877                         Maximal number of shapers.
 878
 879         sim710=         [SCSI,HW]
 880                         See header of drivers/scsi/sim710.c.
 881
 882         simeth=         [IA-64]
 883         simscsi=
 884
 885         sjcd=           [HW,CD]
 886                         Format: <io>,<irq>,<dma>
 887                         See header of drivers/cdrom/sjcd.c.
 888
 889         slram=          [HW,MTD]
 890
 891         smart2=         [HW]
 892                         Format: <io1>[,<io2>[,...,<io8>]]
 893
 894         snd-ad1816a=    [HW,ALSA]
 895
 896         snd-ad1848=     [HW,ALSA]
 897
 898         snd-ali5451=    [HW,ALSA]
 899
 900         snd-als100=     [HW,ALSA]
 901
 902         snd-als4000=    [HW,ALSA]
 903
 904         snd-azt2320=    [HW,ALSA]
 905
 906         snd-cmi8330=    [HW,ALSA]
 907
 908         snd-cmipci=     [HW,ALSA]
 909
 910         snd-cs4231=     [HW,ALSA]
 911
 912         snd-cs4232=     [HW,ALSA]
 913
 914         snd-cs4236=     [HW,ALSA]
 915
 916         snd-cs4281=     [HW,ALSA]
 917
 918         snd-cs46xx=     [HW,ALSA]
 919
 920         snd-dt019x=     [HW,ALSA]
 921
 922         snd-dummy=      [HW,ALSA]
 923
 924         snd-emu10k1=    [HW,ALSA]
 925
 926         snd-ens1370=    [HW,ALSA]
 927
 928         snd-ens1371=    [HW,ALSA]
 929
 930         snd-es968=      [HW,ALSA]
 931
 932         snd-es1688=     [HW,ALSA]
 933
 934         snd-es18xx=     [HW,ALSA]
 935
 936         snd-es1938=     [HW,ALSA]
 937
 938         snd-es1968=     [HW,ALSA]
 939
 940         snd-fm801=      [HW,ALSA]
 941
 942         snd-gusclassic= [HW,ALSA]
 943
 944         snd-gusextreme= [HW,ALSA]
 945
 946         snd-gusmax=     [HW,ALSA]
 947
 948         snd-hdsp=       [HW,ALSA]
 949
 950         snd-ice1712=    [HW,ALSA]
 951
 952         snd-intel8x0=   [HW,ALSA]
 953
 954         snd-interwave=  [HW,ALSA]
 955
 956         snd-interwave-stb=
 957                         [HW,ALSA]
 958
 959         snd-korg1212=   [HW,ALSA]
 960
 961         snd-maestro3=   [HW,ALSA]
 962
 963         snd-mpu401=     [HW,ALSA]
 964
 965         snd-mtpav=      [HW,ALSA]
 966
 967         snd-nm256=      [HW,ALSA]
 968
 969         snd-opl3sa2=    [HW,ALSA]
 970
 971         snd-opti92x-ad1848=
 972                         [HW,ALSA]
 973
 974         snd-opti92x-cs4231=
 975                         [HW,ALSA]
 976
 977         snd-opti93x=    [HW,ALSA]
 978
 979         snd-pmac=       [HW,ALSA]
 980
 981         snd-rme32=      [HW,ALSA]
 982
 983         snd-rme96=      [HW,ALSA]
 984
 985         snd-rme9652=    [HW,ALSA]
 986
 987         snd-sb8=        [HW,ALSA]
 988
 989         snd-sb16=       [HW,ALSA]
 990
 991         snd-sbawe=      [HW,ALSA]
 992
 993         snd-serial=     [HW,ALSA]
 994
 995         snd-sgalaxy=    [HW,ALSA]
 996
 997         snd-sonicvibes= [HW,ALSA]
 998
 999         snd-sun-amd7930=
1000                         [HW,ALSA]
1001
1002         snd-sun-cs4231= [HW,ALSA]
1003
1004         snd-trident=    [HW,ALSA]
1005
1006         snd-usb-audio=  [HW,ALSA,USB]
1007
1008         snd-via82xx=    [HW,ALSA]
1009
1010         snd-virmidi=    [HW,ALSA]
1011
1012         snd-wavefront=  [HW,ALSA]
1013
1014         snd-ymfpci=     [HW,ALSA]
1015
1016         sonicvibes=     [HW,OSS]
1017                         Format: <reverb>
1018
1019         sonycd535=      [HW,CD]
1020                         Format: <io>[,<irq>]
1021
1022         sonypi=         [HW] Sony Programmable I/O Control Device driver
1023                         Format: <minor>,<verbose>,<fnkeyinit>,<camera>,<compat>,<nojogdial>
1024
1025         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1026                         See Documentation/specialix.txt.
1027
1028         speedstep_coppermine=
1029                         [HW,IA-32] Take CPU in your notebook as SpeedStep-capable
1030                         See comment before function speedstep_setup() in
1031                         arch/i386/kernel/cpu/cpufreq/speedstep.c.
1032
1033         spia_io_base=   [HW,MTD]
1034         spia_fio_base=
1035         spia_pedr=
1036         spia_peddr=
1037
1038         sscape=         [HW,OSS]
1039                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1040
1041         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1042                         See Documentation/scsi/st.txt.
1043
1044         st0x=           [HW,SCSI]
1045                         See header of drivers/scsi/seagate.c.
1046
1047         sti=            [HW]
1048                         Format: <num>
1049                         Set the STI (builtin display/keyboard on the HP-PARISC
1050                         machines) console (graphic card) which should be used
1051                         as the initial boot-console.
1052                         See also comment in drivers/video/console/sticore.c.
1053
1054         sti_font=       [HW]
1055                         See comment in drivers/video/console/sticore.c.
1056
1057         stifb=          [HW]
1058                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1059
1060         stram_swap=     [HW,M68k]
1061
1062         swiotlb=        [IA-64] Number of I/O TLB slabs
1063
1064         switches=       [HW,M68k]
1065
1066         sym53c416=      [HW,SCSI]
1067                         See header of drivers/scsi/sym53c416.c.
1068
1069         sym53c8xx=      [HW,SCSI]
1070                         See Documentation/scsi/ncr53c8xx.txt.
1071
1072         t128=           [HW,SCSI]
1073                         See header of drivers/scsi/t128.c.
1074
1075         tdfx=           [HW,DRM]
1076
1077         tgfx=           [HW,JOY] TurboGraFX parallel port interface
1078         tgfx_2=         See Documentation/input/joystick-parport.txt.
1079         tgfx_3=
1080
1081         tipar=          [HW]
1082                         See header of drivers/char/tipar.c.
1083
1084         tiusb=          [HW,USB] Texas Instruments' USB GraphLink (aka SilverLink)
1085                         Format: <timeout>
1086
1087         tmc8xx=         [HW,SCSI]
1088                         See header of drivers/scsi/seagate.c.
1089
1090         tmscsim=        [HW,SCSI]
1091                         See comment before function dc390_setup() in
1092                         drivers/scsi/tmscsim.c.
1093
1094         tp720=          [HW,PS2]
1095
1096         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1097                         Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1098
1099         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1100                         See header of drivers/scsi/u14-34f.c.
1101
1102         uart401=        [HW,OSS]
1103                         Format: <io>,<irq>
1104
1105         uart6850=       [HW,OSS]
1106                         Format: <io>,<irq>
1107
1108         video=          [FB] Frame buffer configuration
1109                         See Documentation/fb/modedb.txt.
1110
1111         vga=            [BOOT,IA-32] Select a particular video mode
1112                         See Documentation/i386/boot.txt and Documentation/svga.txt.
1113                         Use vga=ask for menu.
1114                         This is actually a boot loader parameter; the value is
1115                         passed to the kernel using a special protocol.
1116
1117         vmhalt=         [KNL,S390]
1118
1119         vmpoff=         [KNL,S390]
1120
1121         waveartist=     [HW,OSS]
1122                         Format: <io>,<irq>,<dma>,<dma2>
1123
1124         wd33c93=        [HW,SCSI]
1125                         See header of drivers/scsi/wd33c93.c.
1126
1127         wd7000=         [HW,SCSI]
1128                         See header of drivers/scsi/wd7000.c.
1129
1130         wdt=            [WDT] Watchdog
1131                         See Documentation/watchdog.txt.
1132
1133         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1134         xd_geo=         See header of drivers/block/xd.c.
1135
1136         xirc2ps_cs=     [NET,PCMCIA]
1137                         Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1138
1139
1140
1141 Changelog:
1142
1143         The last known update (for 2.4.0) - the changelog was not kept before.
1144         2000-06-??      Mr. Unknown
1145
1146         Update for 2.5.49, description for most of the options introduced,
1147         references to other documentation (C files, READMEs, ..), added S390,
1148         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1149         reformatting.
1150         2002-11-24      Petr Baudis <pasky@ucw.cz>
1151                         Randy Dunlap <randy.dunlap@verizon.net>
1152
1153 TODO:
1154
1155         Add documentation for ALSA options.
1156         Add more DRM drivers.