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         IOSCHED More than one I/O scheduler is enabled.
  28         IP_PNP  IP DCHP, BOOTP, or RARP is enabled.
  29         ISAPNP  ISA PnP code is enabled.
  30         ISDN    Appropriate ISDN support is enabled.
  31         JOY     Appropriate joystick support is enabled.
  32         LP      Printer support is enabled.
  33         LOOP    Loopback device support is enabled.
  34         M68k    M68k architecture is enabled.
  35                         These options have more detailed description inside of
  36                         Documentation/m68k/kernel-options.txt.
  37         MCA     MCA bus support is enabled.
  38         MDA     MDA console support is enabled.
  39         MOUSE   Appropriate mouse support is enabled.
  40         MTD     MTD support is enabled.
  41         NET     Appropriate network support is enabled.
  42         NFS     Appropriate NFS support is enabled.
  43         OSS     OSS sound support is enabled.
  44         PARIDE  The ParIDE subsystem is enabled.
  45         PCI     PCI bus support is enabled.
  46         PCMCIA  The PCMCIA subsystem is enabled.
  47         PNP     Plug & Play support is enabled.
  48         PPC     PowerPC architecture is enabled.
  49         PPT     Parallel port support is enabled.
  50         PS2     Appropriate PS/2 support is enabled.
  51         RAM     RAM disk support is enabled.
  52         S390    S390 architecture is enabled.
  53         SCSI    Appropriate SCSI support is enabled.
  54                         A lot of drivers has their options described inside of
  55                         Documentation/scsi/.
  56         SERIAL  Serial support is enabled.
  57         SMP     The kernel is an SMP kernel.
  58         SPARC   Sparc architecture is enabled.
  59         SWSUSP  Software suspension is enabled.
  60         TS      Appropriate touchscreen support is enabled.
  61         USB     USB support is enabled.
  62         V4L     Video For Linux support is enabled.
  63         VGA     The VGA console has been enabled.
  64         VT      Virtual terminal support is enabled.
  65         WDT     Watchdog support is enabled.
  66         XT      IBM PC/XT MFM hard disk support is enabled.
  67
  68 In addition, the following text indicates that the option:
  69
  70         BUGS=   Relates to possible processor bugs on the said processor.
  71         KNL     Is a kernel start-up parameter.
  72         BOOT    Is a boot loader parameter.
  73
  74 Parameters denoted with BOOT are actually interpreted by the boot
  75 loader, and have no meaning to the kernel directly.
  76 Do not modify the syntax of boot loader parameters without extreme
  77 need or coordination with <Documentation/i386/boot.txt>.
  78
  79 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  80 a trailing = on the name of any parameter states that that parameter will
  81 be entered as an environment variable, whereas its absence indicates that
  82 it will appear as a kernel argument readable via /proc/cmdline by programs
  83 running once the system is up.
  84
  85         53c7xx=         [HW,SCSI] Amiga SCSI controllers
  86                         See header of drivers/scsi/53c7xx.c.
  87                         See also Documentation/scsi/ncr53c7xx.txt.
  88
  89         98busmouse.irq= [HW,MOUSE] PC-9801 Bus Mouse Driver
  90                         Format: <irq>, default is 13
  91
  92         acpi=           [HW,ACPI] Advanced Configuration and Power Interface
  93                         Format: { force | off | ht }
  94                         force -- enables ACPI for systems with default off
  95                         off -- disabled ACPI for systems with default on
  96                         ht -- run only enough ACPI to enable Hyper Threading
  97                         See also Documentation/pm.txt.
  98
  99         acpi_pic_sci=   [HW,ACPI] ACPI System Control Interrupt trigger mode
 100                         Format: { level | edge }
 101                         level   Force PIC-mode SCI to Level Trigger (default)
 102                         edge    Force PIC-mode SCI to Edge Trigge
 103
 104         acpi_irq_balance        [HW,ACPI] ACPI will balance active IRQs
 105                                 default in APIC mode
 106
 107         acpi_irq_nobalance      [HW,ACPI] ACPI will not move active IRQs (default)
 108                                 default in PIC mode
 109
 110         acpi_irq_pci=   [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
 111                         Format: <irq>,<irq>...
 112
 113         acpi_irq_isa=   [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
 114                         Format: <irq>,<irq>...
 115
 116         ad1816=         [HW,OSS]
 117                         Format: <io>,<irq>,<dma>,<dma2>
 118                         See also Documentation/sound/oss/AD1816.
 119
 120         ad1848=         [HW,OSS]
 121                         Format: <io>,<irq>,<dma>,<dma2>,<type>
 122
 123         adlib=          [HW,OSS]
 124                         Format: <io>
 125
 126         advansys=       [HW,SCSI]
 127                         See header of drivers/scsi/advansys.c.
 128
 129         advwdt=         [HW,WDT] Advantech WDT
 130                         Format: <iostart>,<iostop>
 131
 132         aedsp16=        [HW,OSS] Audio Excel DSP 16
 133                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 134                         See also header of sound/oss/aedsp16.c.
 135
 136         aha152x=        [HW,SCSI]
 137                         See Documentation/scsi/aha152x.txt.
 138
 139         aha1542=        [HW,SCSI]
 140                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 141
 142         aic7xxx=        [HW,SCSI]
 143                         See Documentation/scsi/aic7xxx.txt.
 144
 145         aic79xx=        [HW,SCSI]
 146                         See Documentation/scsi/aic79xx.txt.
 147
 148         allowdma0       [ISAPNP]
 149
 150         AM53C974=       [HW,SCSI]
 151                         Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
 152                         See also header of drivers/scsi/AM53C974.c.
 153
 154         amijoy=         [HW,JOY] Amiga joystick support
 155
 156         apc=            [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
 157                         Format: noidle
 158                         Disable APC CPU standby support. SPARCstation-Fox does
 159                         not play well with APC CPU idle - disable it if you have
 160                         APC and your system crashes randomly.
 161
 162         apm=            [APM] Advanced Power Management
 163                         See header of arch/i386/kernel/apm.c.
 164
 165         applicom=       [HW]
 166                         Format: <mem>,<irq>
 167
 168         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 169                         Format: <io>,<irq>,<nodeID>
 170
 171         ataflop=        [HW,M68k]
 172
 173         atarimouse=     [HW,MOUSE] Atari Mouse
 174
 175         atascsi=        [HW,SCSI] Atari SCSI
 176
 177         atkbd.set=      [HW] Select keyboard code set
 178                         Format: <int>
 179         atkbd.softrepeat=
 180                         [HW] Use software keyboard repeat
 181         atkbd.reset=    [HW] Reset keyboard during initialization
 182
 183         autotest        [IA64]
 184
 185         awe=            [HW,OSS] AWE32/SB32/AWE64 wave table synth
 186                         Format: <io>,<memsize>,<isapnp>
 187
 188         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 189                         Format: <io>,0x79 (?)
 190
 191         baycom_epp=     [HW,AX25]
 192                         Format: <io>,<mode>
 193
 194         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 195                         Format: <io>,<mode>
 196                         See header of drivers/net/hamradio/baycom_par.c.
 197
 198         baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 199                         Format: <io>,<irq>,<mode>[,<baud>]
 200                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 201
 202         baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 203                         Format: <io>,<irq>,<mode>
 204                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 205
 206         blkmtd_device=  [HW,MTD]
 207         blkmtd_erasesz=
 208         blkmtd_ro=
 209         blkmtd_bs=
 210         blkmtd_count=
 211
 212         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 213         bttv.radio=     Most important insmod options are available as kernel args too.
 214         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 215         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 216
 217         BusLogic=       [HW,SCSI]
 218                         See drivers/scsi/BusLogic.c, comment before function
 219                         BusLogic_ParseDriverOptions().
 220
 221         c101=           [NET] Moxa C101 synchronous serial card
 222
 223         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 224                         Sometimes CPU hardware bugs make them report the cache
 225                         size incorrectly. The kernel will attempt work arounds
 226                         to fix known problems, but for some CPUs it is not
 227                         possible to determine what the correct size should be.
 228                         This option provides an override for these situations.
 229
 230         cdu31a=         [HW,CD]
 231                         Format: <io>,<irq>[,PAS]
 232                         See header of drivers/cdrom/cdu31a.c.
 233
 234         chandev=        [HW,NET] Generic channel device initialisation
 235
 236         clock=          [BUGS=IA-32, HW] gettimeofday timesource override.
 237                         Forces specified timesource (if avaliable) to be used
 238                         when calculating gettimeofday(). If specicified timesource
 239                         is not avalible, it defaults to PIT.
 240                         Format: { pit | tsc | cyclone | ... }
 241
 242         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
 243                         Format: disable
 244
 245         cm206=          [HW,CD]
 246                         Format: { auto | [<io>,][<irq>] }
 247
 248         com20020=       [HW,NET] ARCnet - COM20020 chipset
 249                         Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 250
 251         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 252                         Format: <io>[,<irq>]
 253
 254         com90xx=        [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
 255                         Format: <io>[,<irq>[,<memstart>]]
 256
 257         condev=         [HW,S390] console device
 258         conmode=
 259
 260         console=        [KNL] Output console
 261                         Console device and comm spec (speed, control, parity).
 262
 263         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 264                         Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 265
 266         cpia_pp=        [HW,PPT]
 267                         Format: { parport<nr> | auto | none }
 268
 269         cs4232=         [HW,OSS]
 270                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 271
 272         cs89x0_dma=     [HW,NET]
 273                         Format: <dma>
 274
 275         cs89x0_media=   [HW,NET]
 276                         Format: { rj45 | aui | bnc }
 277
 278         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 279
 280         dasd=           [HW,NET]
 281                         See header of drivers/s390/block/dasd_devmap.c.
 282
 283         db9=            [HW,JOY]
 284         db9_2=
 285         db9_3=
 286
 287         debug           [KNL] Enable kernel debugging (events log level).
 288
 289         decnet=         [HW,NET]
 290                         Format: <area>[,<node>]
 291                         See also Documentation/networking/decnet.txt.
 292
 293         devfs=          [DEVFS]
 294                         See Documentation/filesystems/devfs/boot-options.
 295
 296         digi=           [HW,SERIAL]
 297                         IO parameters + enable/disable command.
 298
 299         digiepca=       [HW,SERIAL]
 300                         See drivers/char/README.epca and
 301                         Documentation/digiepca.txt.
 302
 303         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 304                         support available.
 305                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 306
 307         dmasound=       [HW,OSS] Sound subsystem buffers
 308
 309         dscc4.setup=    [NET]
 310
 311         dtc3181e=       [HW,SCSI]
 312
 313         eata=           [HW,SCSI]
 314
 315         eda=            [HW,PS2]
 316
 317         edb=            [HW,PS2]
 318
 319         eicon=          [HW,ISDN]
 320                         Format: <id>,<membase>,<irq>
 321
 322         eisa_irq_edge=  [PARISC]
 323                         See header of drivers/parisc/eisa.c.
 324
 325         elanfreq=       [IA-32]
 326                         See comment before function elanfreq_setup() in
 327                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 328
 329         elevator=       [IOSCHED]
 330                         Format: {"as"|"cfq"|"deadline"|"noop"}
 331                         See Documentation/as-iosched.txt for details
 332
 333         es1370=         [HW,OSS]
 334                         Format: <lineout>[,<micbias>]
 335                         See also header of sound/oss/es1370.c.
 336
 337         es1371=         [HW,OSS]
 338                         Format: <spdif>,[<nomix>,[<amplifier>]]
 339                         See also header of sound/oss/es1371.c.
 340
 341         ether=          [HW,NET] Ethernet cards parameters
 342                         This option is obsoleted by the "netdev=" option, which
 343                         has equivalent usage. See its documentation for details.
 344
 345         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 346                         Format: <io>[,<irq>]
 347
 348         fd_mcs=         [HW,SCSI]
 349                         See header of drivers/scsi/fd_mcs.c.
 350
 351         fdomain=        [HW,SCSI]
 352                         See header of drivers/scsi/fdomain.c.
 353
 354         floppy=         [HW]
 355                         See Documentation/floppy.txt.
 356
 357         ftape=          [HW] Floppy Tape subsystem debugging options.
 358                         See Documentation/ftape.txt.
 359
 360         gamma=          [HW,DRM]
 361
 362         gc=             [HW,JOY]
 363         gc_2=           See Documentation/input/joystick-parport.txt.
 364         gc_3=
 365
 366         gdth=           [HW,SCSI]
 367                         See header of drivers/scsi/gdth.c.
 368
 369         gpt             [EFI] Forces disk with valid GPT signature but
 370                         invalid Protective MBR to be treated as GPT.
 371
 372         gscd=           [HW,CD]
 373                         Format: <io>
 374
 375         gt96100eth=     [NET] MIPS GT96100 Advanced Communication Controller
 376
 377         gus=            [HW,OSS]
 378                         Format: <io>,<irq>,<dma>,<dma16>
 379
 380         gvp11=          [HW,SCSI]
 381
 382         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 383
 384         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 385                         Format: <cyl>,<head>,<sect>
 386
 387         hd?=            [HW] (E)IDE subsystem
 388         hd?lun=         See Documentation/ide.txt.
 389
 390         hisax=          [HW,ISDN]
 391                         See Documentation/isdn/README.HiSax.
 392
 393         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 394
 395         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
 396
 397         i8042.direct    [HW] Put keyboard port into non-translated mode
 398         i8042.dumbkbd   [HW] Pretend that controlled can only read data from
 399                              keyboard and can not control its state
 400                              (Don't attempt to blink the leds)
 401         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 402         i8042.nomux     [HW] Don't check presence of an active multiplexing
 403                              controller
 404         i8042.reset     [HW] Reset the controller during init and cleanup
 405         i8042.unlock    [HW] Unlock (ignore) the keylock
 406
 407         i810=           [HW,DRM]
 408
 409         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 410                         See Documentation/mca.txt.
 411
 412         icn=            [HW,ISDN]
 413                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 414
 415         ide?=           [HW] (E)IDE subsystem
 416                         Config (iomem/irq), tuning or debugging
 417                         (serialize,reset,no{dma,tune,probe}) or chipset
 418                         specific parameters.
 419                         See Documentation/ide.txt.
 420
 421         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 422                         See Documentation/ide.txt.
 423
 424         idle=           [HW]
 425                         Format: idle=poll or idle=halt
 426
 427         in2000=         [HW,SCSI]
 428                         See header of drivers/scsi/in2000.c.
 429
 430         init=           [KNL]
 431                         Format: <full_path>
 432                         Run specified binary instead of /sbin/init as init
 433                         process.
 434
 435         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 436                         for working out where the kernel is dying during
 437                         startup.
 438
 439         initrd=         [BOOT] Specify the location of the initial ramdisk
 440
 441         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 442                         Format: <irq>
 443
 444         inttest=        [IA64]
 445
 446         io7=            [HW] IO7 for Marvel based alpha systems
 447                         See comment before marvel_specify_io7 in
 448                         arch/alpha/kernel/core_marvel.c.
 449
 450         ip=             [IP_PNP]
 451                         See Documentation/nfsroot.txt.
 452
 453         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 454                         See comment before ip2_setup() in drivers/char/ip2.c.
 455
 456         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 457                         See header of drivers/scsi/ips.c.
 458
 459         isapnp=         [ISAPNP]
 460                         Format: <RDP>, <reset>, <pci_scan>, <verbosity>
 461
 462         isp16=          [HW,CD]
 463                         Format: <io>,<irq>,<dma>,<setup>
 464
 465         iucv=           [HW,NET]
 466
 467         js=             [HW,JOY] Analog joystick
 468                         See Documentation/input/joystick.txt.
 469
 470         keepinitrd      [HW,ARM]
 471
 472         l2cr=           [PPC]
 473
 474         lapic           [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
 475
 476         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 477                         Format: addr:<io>,irq:<irq>
 478
 479         llsc*=          [IA64]
 480                         See function print_params() in arch/ia64/sn/kernel/llsc4.c.
 481
 482         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 483                         See Documentation/ramdisk.txt.
 484
 485         lockd.udpport=  [NFS]
 486
 487         lockd.tcpport=  [NFS]
 488
 489         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 490                         Format: <irq>
 491
 492         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 493                         Format is n, nk, nM.  n must be a power of two.  The
 494                         default is set in kernel config.
 495
 496         lp=0            [LP]    Specify parallel ports to use, e.g,
 497         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 498         lp=reset                first parallel port). 'lp=0' disables the
 499         lp=auto                 printer driver. 'lp=reset' (which can be
 500                                 specified in addition to the ports) causes
 501                                 attached printers to be reset. Using
 502                                 lp=port1,port2,... specifies the parallel ports
 503                                 to associate lp devices with, starting with
 504                                 lp0. A port specification may be 'none' to skip
 505                                 that lp device, or a parport name such as
 506                                 'parport0'. Specifying 'lp=auto' instead of a
 507                                 port specification list means that device IDs
 508                                 from each port should be examined, to see if
 509                                 an IEEE 1284-compliant printer is attached; if
 510                                 so, the driver will manage that printer.
 511                                 See also header of drivers/char/lp.c.
 512
 513         ltpc=           [NET]
 514                         Format: <io>,<irq>,<dma>
 515
 516         mac5380=        [HW,SCSI]
 517                         Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 518
 519         mac53c9x=       [HW,SCSI]
 520                         Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 521
 522         mad16=          [HW,OSS]
 523                         Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
 524
 525         maui=           [HW,OSS]
 526                         Format: <io>,<irq>
 527
 528         max_loop=       [LOOP] Maximum number of loopback devices that can
 529                         be mounted
 530                         Format: <1-256>
 531
 532         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 533                         should make use of
 534
 535         max_scsi_luns=  [SCSI]
 536
 537         max_scsi_report_luns=
 538                         [SCSI] Maximum number of LUNs received
 539                         Should be between 1 and 16384.
 540
 541         mca-pentium     [BUGS=IA-32]
 542
 543         mcatest=        [IA-64]
 544
 545         mcd=            [HW,CD]
 546                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 547
 548         mcdx=           [HW,CD]
 549
 550         mce             [IA-32] Machine Check Exception
 551
 552         md=             [HW] RAID subsystems devices and level
 553                         See Documentation/md.txt.
 554
 555         mdacon=         [MDA]
 556                         Format: <first>,<last>
 557                         Specifies range of consoles to be captured by the MDA.
 558
 559         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 560                         Amount of memory to be used when the kernel is not able
 561                         to see the whole system memory or for test.
 562
 563         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 564                         memory.
 565
 566         memmap=exactmap [KNL,IA-32] Enable setting of an exact
 567                         E820 memory map, as specified by the user.
 568                         Such memmap=exactmap lines can be constructed based on
 569                         BIOS output or other requirements. See the memmap=nn@ss
 570                         option description.
 571
 572         memmap=nn[KMG]@ss[KMG]
 573                         [KNL] Force usage of a specific region of memory
 574                         Region of memory to be used, from ss to ss+nn.
 575
 576         memmap=nn[KMG]#ss[KMG]
 577                         [KNL,ACPI] Mark specific memory as ACPI data.
 578                         Region of memory to be used, from ss to ss+nn.
 579
 580         memmap=nn[KMG]$ss[KMG]
 581                         [KNL,ACPI] Mark specific memory as reserved.
 582                         Region of memory to be used, from ss to ss+nn.
 583
 584         meye=           [HW] Set MotionEye Camera parameters
 585                         See Documentation/video4linux/meye.txt.
 586
 587         mga=            [HW,DRM]
 588
 589         mousedev.xres   [MOUSE] Horizontal screen resolution, used for devices
 590                         reporting absolute coordinates, such as tablets
 591         mousedev.yres   [MOUSE] Vertical screen resolution, used for devices
 592                         reporting absolute coordinates, such as tablets
 593
 594         mpu401=         [HW,OSS]
 595                         Format: <io>,<irq>
 596
 597         MTD_Partition=  [MTD]
 598                         Format: <name>,<region-number>,<size>,<offset>
 599
 600         MTD_Region=     [MTD]
 601                         Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
 602
 603         mtdparts=       [MTD]
 604                         See drivers/mtd/cmdline.c.
 605
 606         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
 607
 608         NCR_D700=       [HW,SCSI]
 609                         See header of drivers/scsi/NCR_D700.c.
 610
 611         ncr5380=        [HW,SCSI]
 612
 613         ncr53c400=      [HW,SCSI]
 614
 615         ncr53c400a=     [HW,SCSI]
 616
 617         ncr53c406a=     [HW,SCSI]
 618
 619         ncr53c8xx=      [HW,SCSI]
 620
 621         netdev=         [NET] Network devices parameters
 622                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
 623                         Note that mem_start is often overloaded to mean
 624                         something different and driver-specific.
 625
 626         nfsaddrs=       [NFS]
 627                         See Documentation/nfsroot.txt.
 628
 629         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
 630                         See Documentation/nfsroot.txt.
 631
 632         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 633
 634         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
 635                         emulation library even if a 387 maths coprocessor
 636                         is present.
 637
 638         noalign         [KNL,ARM]
 639
 640         noapic          [SMP,APIC] Tells the kernel not to make use of any
 641                         APIC that may be present on the system.
 642
 643         noasync         [HW,M68K] Disables async and sync negotiation for
 644                         all devices.
 645
 646         nocache         [ARM]
 647
 648         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
 649
 650         noexec          [IA-64]
 651
 652         nofxsr          [BUGS=IA-32]
 653
 654         nohighio        [BUGS=IA-32] Disable highmem block I/O.
 655
 656         nohlt           [BUGS=ARM]
 657
 658         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
 659                         instruction doesn't work correctly and not to
 660                         use it.
 661
 662         noirqdebug      [IA-32] Disables the code which attempts to detect and
 663                         disable unhandled interrupt sources.
 664
 665         noisapnp        [ISAPNP] Disables ISA PnP code.
 666
 667         noinitrd        [RAM] Tells the kernel not to load any configured
 668                         initial RAM disk.
 669
 670         nointroute      [IA-64]
 671
 672         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 673
 674         nomce           [IA-32] Machine Check Exception
 675
 676         noresume        [SWSUSP] Disables resume and restore original swap space.
 677
 678         no-scroll       [VGA] Disables scrollback.
 679                         This is required for the Braillex ib80-piezo Braille
 680                         reader made by F.H. Papenmeier (Germany).
 681
 682         nosbagart       [IA-64]
 683
 684         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
 685
 686         nosync          [HW,M68K] Disables sync negotiation for all devices.
 687
 688         notsc           [BUGS=IA-32] Disable Time Stamp Counter
 689
 690         nousb           [USB] Disable the USB subsystem
 691
 692         nowb            [ARM]
 693
 694         opl3=           [HW,OSS]
 695                         Format: <io>
 696
 697         opl3sa=         [HW,OSS]
 698                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
 699
 700         opl3sa2=        [HW,OSS]
 701                         Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
 702
 703         oprofile.timer= [HW]
 704                         Use timer interrupt instead of performance counters
 705
 706         optcd=          [HW,CD]
 707                         Format: <io>
 708
 709         osst=           [HW,SCSI] SCSI Tape Driver
 710                         Format: <buffer_size>,<write_threshold>
 711                         See also Documentation/scsi/st.txt.
 712
 713         panic=          [KNL] Kernel behaviour on panic
 714                         Format: <timeout>
 715
 716         parport=0       [HW,PPT]        Specify parallel ports. 0 disables.
 717         parport=auto                    Use 'auto' to force the driver to use
 718         parport=0xBBB[,IRQ[,DMA]]       any IRQ/DMA settings detected (the
 719                                         default is to ignore detected IRQ/DMA
 720                                         settings because of possible
 721                                         conflicts). You can specify the base
 722                                         address, IRQ, and DMA settings; IRQ and
 723                                         DMA should be numbers, or 'auto' (for
 724                                         using detected settings on that
 725                                         particular port), or 'nofifo' (to avoid
 726                                         using a FIFO even if it is detected).
 727                                         Parallel ports are assigned in the
 728                                         order they are specified on the command
 729                                         line, starting with parport0.
 730
 731         pas2=           [HW,OSS]
 732                         Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
 733
 734         pas16=          [HW,SCSI]
 735                         See header of drivers/scsi/pas16.c.
 736
 737         pcbit=          [HW,ISDN]
 738
 739         pcd.            [PARIDE]
 740                         See header of drivers/block/paride/pcd.c.
 741                         See also Documentation/paride.txt.
 742
 743         pci=option[,option...]          [PCI] various PCI subsystem options:
 744                 off                     [IA-32] don't probe for the PCI bus
 745                 bios                    [IA-32] force use of PCI BIOS, don't access
 746                                         the hardware directly. Use this if your machine
 747                                         has a non-standard PCI host bridge.
 748                 nobios                  [IA-32] disallow use of PCI BIOS, only direct
 749                                         hardware access methods are allowed. Use this
 750                                         if you experience crashes upon bootup and you
 751                                         suspect they are caused by the BIOS.
 752                 conf1                   [IA-32] Force use of PCI Configuration Mechanism 1.
 753                 conf2                   [IA-32] Force use of PCI Configuration Mechanism 2.
 754                 nosort                  [IA-32] Don't sort PCI devices according to
 755                                         order given by the PCI BIOS. This sorting is done
 756                                         to get a device order compatible with older kernels.
 757                 biosirq                 [IA-32] Use PCI BIOS calls to get the interrupt
 758                                         routing table. These calls are known to be buggy
 759                                         on several machines and they hang the machine when used,
 760                                         but on other computers it's the only way to get the
 761                                         interrupt routing table. Try this option if the kernel
 762                                         is unable to allocate IRQs or discover secondary PCI
 763                                         buses on your motherboard.
 764                 rom                     [IA-32] Assign address space to expansion ROMs.
 765                                         Use with caution as certain devices share address
 766                                         decoders between ROMs and other resources.
 767                 irqmask=0xMMMM          [IA-32] Set a bit mask of IRQs allowed to be assigned
 768                                         automatically to PCI devices. You can make the kernel
 769                                         exclude IRQs of your ISA cards this way.
 770                 lastbus=N               [IA-32] Scan all buses till bus #N. Can be useful
 771                                         if the kernel is unable to find your secondary buses
 772                                         and you want to tell it explicitly which ones they are.
 773                 assign-busses           [IA-32] Always assign all PCI bus
 774                                         numbers ourselves, overriding
 775                                         whatever the firmware may have
 776                                         done.
 777                 usepirqmask             [IA-32] Honor the possible IRQ mask
 778                                         stored in the BIOS $PIR table. This is
 779                                         needed on some systems with broken
 780                                         BIOSes, notably some HP Pavilion N5400
 781                                         and Omnibook XE3 notebooks. This will
 782                                         have no effect if ACPI IRQ routing is
 783                                         enabled.
 784                 noacpi                  [IA-32] Do not use ACPI for IRQ routing.
 785
 786         pcmv=           [HW,PCMCIA] BadgePAD 4
 787
 788         pd.             [PARIDE]
 789                         See Documentation/paride.txt.
 790
 791         pf.             [PARIDE]
 792                         See Documentation/paride.txt.
 793
 794         pg.             [PARIDE]
 795                         See Documentation/paride.txt.
 796
 797         pirq=           [SMP,APIC] Manual mp-table setup
 798                         See Documentation/i386/IO-APIC.txt.
 799
 800         plip=           [PPT,NET] Parallel port network link
 801                         Format: { parport<nr> | timid | 0 }
 802                         See also Documentation/parport.txt.
 803
 804         pnpbios=        [ISAPNP]
 805                         { on | off | curr | res | no-curr | no-res }
 806
 807         pnp_reserve_irq=
 808                         [ISAPNP] Exclude IRQs for the autoconfiguration
 809
 810         pnp_reserve_dma=
 811                         [ISAPNP] Exclude DMAs for the autoconfiguration
 812
 813         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
 814                         Ranges are in pairs (I/O port base and size).
 815
 816         pnp_reserve_mem=
 817                         [ISAPNP] Exclude memory regions for the autoconfiguration
 818                         Ranges are in pairs (memory base and size).
 819
 820         profile=        [KNL] Enable kernel profiling via /proc/profile
 821                         (param: profile step/bucket size as a power of 2)
 822
 823         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
 824                         before loading.
 825                         See Documentation/ramdisk.txt.
 826
 827         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
 828                         probe for (bare|imps|exps).
 829         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
 830                         per second.
 831         psmouse.resetafter=
 832                         [HW,MOUSE] Try to reset Synaptics Touchpad after so many
 833                         bad packets (0 = never).
 834         psmouse.resolution=
 835                         [HW,MOUSE] Set desired mouse resolution, in dpi.
 836         psmouse.smartscroll=
 837                         [HW,MOUSE] Controls Logitech smartscroll autorepeat,
 838                         0 = disabled, 1 = enabled (default).
 839
 840         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
 841                         Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
 842
 843         pt.             [PARIDE]
 844                         See Documentation/paride.txt.
 845
 846         quiet=          [KNL] Disable log messages
 847
 848         r128=           [HW,DRM]
 849
 850         raid=           [HW,RAID]
 851                         See Documentation/md.txt.
 852
 853         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
 854                         See Documentation/ramdisk.txt.
 855
 856         ramdisk_blocksize=
 857                         [RAM]
 858                         See Documentation/ramdisk.txt.
 859
 860         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
 861                         New name for the ramdisk parameter.
 862                         See Documentation/ramdisk.txt.
 863
 864         ramdisk_start=  [RAM] Starting block of RAM disk image (so you can
 865                         place it after the kernel image on a boot floppy).
 866                         See Documentation/ramdisk.txt.
 867
 868         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
 869                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
 870                         See arch/*/kernel/reboot.c.
 871
 872         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
 873
 874         resume=         [SWSUSP] Specify the partition device for software suspension
 875
 876         riscom8=        [HW,SERIAL]
 877                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
 878
 879         ro              [KNL] Mount root device read-only on boot
 880
 881         root=           [KNL] Root filesystem
 882
 883         rootflags=      [KNL] Set root filesystem mount option string
 884
 885         rootfstype=     [KNL] Set root filesystem type
 886
 887         rw              [KNL] Mount root device read-write on boot
 888
 889         S               [KNL] Run init in single mode
 890
 891         sa1100ir        [NET]
 892                         See drivers/net/irda/sa1100_ir.c.
 893
 894         sb=             [HW,OSS]
 895                         Format: <io>,<irq>,<dma>,<dma2>
 896
 897         sbni=           [NET] Granch SBNI12 leased line adapter
 898
 899         sbpcd=          [HW,CD] Soundblaster CD adapter
 900                         Format: <io>,<type>
 901                         See a comment before function sbpcd_setup() in
 902                         drivers/cdrom/sbpcd.c.
 903
 904         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
 905                         Format: <io>[,<timeout>[,<isapnp>]]
 906
 907         scsi_debug_*=   [SCSI]
 908                         See drivers/scsi/scsi_debug.c.
 909
 910         scsi_default_dev_flags=
 911                         [SCSI] SCSI default device flags
 912                         Format: <integer>
 913
 914         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
 915                         Format: <vendor>:<model>:<flags>
 916                         (flags are integer value)
 917
 918         scsi_logging=   [SCSI]
 919
 920         scsihosts=      [SCSI]
 921
 922         serialnumber    [BUGS=IA-32]
 923
 924         sf16fm=         [HW] SF16FMI radio driver for Linux
 925                         Format: <io>
 926
 927         sg_def_reserved_size=
 928                         [SCSI]
 929
 930         sgalaxy=        [HW,OSS]
 931                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
 932
 933         shapers=        [NET]
 934                         Maximal number of shapers.
 935
 936         sim710=         [SCSI,HW]
 937                         See header of drivers/scsi/sim710.c.
 938
 939         simeth=         [IA-64]
 940         simscsi=
 941
 942         sjcd=           [HW,CD]
 943                         Format: <io>,<irq>,<dma>
 944                         See header of drivers/cdrom/sjcd.c.
 945
 946         slram=          [HW,MTD]
 947
 948         smart2=         [HW]
 949                         Format: <io1>[,<io2>[,...,<io8>]]
 950
 951         snd-ad1816a=    [HW,ALSA]
 952
 953         snd-ad1848=     [HW,ALSA]
 954
 955         snd-ali5451=    [HW,ALSA]
 956
 957         snd-als100=     [HW,ALSA]
 958
 959         snd-als4000=    [HW,ALSA]
 960
 961         snd-azt2320=    [HW,ALSA]
 962
 963         snd-cmi8330=    [HW,ALSA]
 964
 965         snd-cmipci=     [HW,ALSA]
 966
 967         snd-cs4231=     [HW,ALSA]
 968
 969         snd-cs4232=     [HW,ALSA]
 970
 971         snd-cs4236=     [HW,ALSA]
 972
 973         snd-cs4281=     [HW,ALSA]
 974
 975         snd-cs46xx=     [HW,ALSA]
 976
 977         snd-dt019x=     [HW,ALSA]
 978
 979         snd-dummy=      [HW,ALSA]
 980
 981         snd-emu10k1=    [HW,ALSA]
 982
 983         snd-ens1370=    [HW,ALSA]
 984
 985         snd-ens1371=    [HW,ALSA]
 986
 987         snd-es968=      [HW,ALSA]
 988
 989         snd-es1688=     [HW,ALSA]
 990
 991         snd-es18xx=     [HW,ALSA]
 992
 993         snd-es1938=     [HW,ALSA]
 994
 995         snd-es1968=     [HW,ALSA]
 996
 997         snd-fm801=      [HW,ALSA]
 998
 999         snd-gusclassic= [HW,ALSA]
1000
1001         snd-gusextreme= [HW,ALSA]
1002
1003         snd-gusmax=     [HW,ALSA]
1004
1005         snd-hdsp=       [HW,ALSA]
1006
1007         snd-ice1712=    [HW,ALSA]
1008
1009         snd-intel8x0=   [HW,ALSA]
1010
1011         snd-interwave=  [HW,ALSA]
1012
1013         snd-interwave-stb=
1014                         [HW,ALSA]
1015
1016         snd-korg1212=   [HW,ALSA]
1017
1018         snd-maestro3=   [HW,ALSA]
1019
1020         snd-mpu401=     [HW,ALSA]
1021
1022         snd-mtpav=      [HW,ALSA]
1023
1024         snd-nm256=      [HW,ALSA]
1025
1026         snd-opl3sa2=    [HW,ALSA]
1027
1028         snd-opti92x-ad1848=
1029                         [HW,ALSA]
1030
1031         snd-opti92x-cs4231=
1032                         [HW,ALSA]
1033
1034         snd-opti93x=    [HW,ALSA]
1035
1036         snd-pmac=       [HW,ALSA]
1037
1038         snd-rme32=      [HW,ALSA]
1039
1040         snd-rme96=      [HW,ALSA]
1041
1042         snd-rme9652=    [HW,ALSA]
1043
1044         snd-sb8=        [HW,ALSA]
1045
1046         snd-sb16=       [HW,ALSA]
1047
1048         snd-sbawe=      [HW,ALSA]
1049
1050         snd-serial=     [HW,ALSA]
1051
1052         snd-sgalaxy=    [HW,ALSA]
1053
1054         snd-sonicvibes= [HW,ALSA]
1055
1056         snd-sun-amd7930=
1057                         [HW,ALSA]
1058
1059         snd-sun-cs4231= [HW,ALSA]
1060
1061         snd-trident=    [HW,ALSA]
1062
1063         snd-usb-audio=  [HW,ALSA,USB]
1064
1065         snd-via82xx=    [HW,ALSA]
1066
1067         snd-virmidi=    [HW,ALSA]
1068
1069         snd-wavefront=  [HW,ALSA]
1070
1071         snd-ymfpci=     [HW,ALSA]
1072
1073         sonicvibes=     [HW,OSS]
1074                         Format: <reverb>
1075
1076         sonycd535=      [HW,CD]
1077                         Format: <io>[,<irq>]
1078
1079         sonypi=         [HW] Sony Programmable I/O Control Device driver
1080                         Format: <minor>,<verbose>,<fnkeyinit>,<camera>,<compat>,<nojogdial>
1081
1082         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1083                         See Documentation/specialix.txt.
1084
1085         speedstep_coppermine=
1086                         [HW,IA-32] Take CPU in your notebook as SpeedStep-capable
1087                         See comment before function speedstep_setup() in
1088                         arch/i386/kernel/cpu/cpufreq/speedstep.c.
1089
1090         spia_io_base=   [HW,MTD]
1091         spia_fio_base=
1092         spia_pedr=
1093         spia_peddr=
1094
1095         sscape=         [HW,OSS]
1096                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1097
1098         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1099                         See Documentation/scsi/st.txt.
1100
1101         st0x=           [HW,SCSI]
1102                         See header of drivers/scsi/seagate.c.
1103
1104         sti=            [HW]
1105                         Format: <num>
1106                         Set the STI (builtin display/keyboard on the HP-PARISC
1107                         machines) console (graphic card) which should be used
1108                         as the initial boot-console.
1109                         See also comment in drivers/video/console/sticore.c.
1110
1111         sti_font=       [HW]
1112                         See comment in drivers/video/console/sticore.c.
1113
1114         stifb=          [HW]
1115                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1116
1117         stram_swap=     [HW,M68k]
1118
1119         swiotlb=        [IA-64] Number of I/O TLB slabs
1120
1121         switches=       [HW,M68k]
1122
1123         sym53c416=      [HW,SCSI]
1124                         See header of drivers/scsi/sym53c416.c.
1125
1126         sym53c8xx=      [HW,SCSI]
1127                         See Documentation/scsi/ncr53c8xx.txt.
1128
1129         t128=           [HW,SCSI]
1130                         See header of drivers/scsi/t128.c.
1131
1132         tdfx=           [HW,DRM]
1133
1134         tgfx=           [HW,JOY] TurboGraFX parallel port interface
1135         tgfx_2=         See Documentation/input/joystick-parport.txt.
1136         tgfx_3=
1137
1138         tipar=          [HW]
1139                         See header of drivers/char/tipar.c.
1140
1141         tiusb=          [HW,USB] Texas Instruments' USB GraphLink (aka SilverLink)
1142                         Format: <timeout>
1143
1144         tmc8xx=         [HW,SCSI]
1145                         See header of drivers/scsi/seagate.c.
1146
1147         tmscsim=        [HW,SCSI]
1148                         See comment before function dc390_setup() in
1149                         drivers/scsi/tmscsim.c.
1150
1151         tp720=          [HW,PS2]
1152
1153         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1154                         Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1155
1156         tsdev.xres      [TS] Horizontal screen resolution.
1157         tsdev.yres      [TS] Vertical screen resolution.
1158
1159         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1160                         See header of drivers/scsi/u14-34f.c.
1161
1162         uart401=        [HW,OSS]
1163                         Format: <io>,<irq>
1164
1165         uart6850=       [HW,OSS]
1166                         Format: <io>,<irq>
1167
1168         video=          [FB] Frame buffer configuration
1169                         See Documentation/fb/modedb.txt.
1170
1171         vga=            [BOOT,IA-32] Select a particular video mode
1172                         See Documentation/i386/boot.txt and Documentation/svga.txt.
1173                         Use vga=ask for menu.
1174                         This is actually a boot loader parameter; the value is
1175                         passed to the kernel using a special protocol.
1176
1177         vmhalt=         [KNL,S390]
1178
1179         vmpoff=         [KNL,S390]
1180
1181         waveartist=     [HW,OSS]
1182                         Format: <io>,<irq>,<dma>,<dma2>
1183
1184         wd33c93=        [HW,SCSI]
1185                         See header of drivers/scsi/wd33c93.c.
1186
1187         wd7000=         [HW,SCSI]
1188                         See header of drivers/scsi/wd7000.c.
1189
1190         wdt=            [WDT] Watchdog
1191                         See Documentation/watchdog/watchdog.txt.
1192
1193         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1194         xd_geo=         See header of drivers/block/xd.c.
1195
1196         xirc2ps_cs=     [NET,PCMCIA]
1197                         Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1198
1199
1200
1201 Changelog:
1202
1203         The last known update (for 2.4.0) - the changelog was not kept before.
1204         2000-06-??      Mr. Unknown
1205
1206         Update for 2.5.49, description for most of the options introduced,
1207         references to other documentation (C files, READMEs, ..), added S390,
1208         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1209         reformatting.
1210         2002-11-24      Petr Baudis <pasky@ucw.cz>
1211                         Randy Dunlap <randy.dunlap@verizon.net>
1212
1213 TODO:
1214
1215         Add documentation for ALSA options.
1216         Add more DRM drivers.