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   1 February 2003             Kernel Parameters                     v2.5.59
   2                           ~~~~~~~~~~~~~~~~~
   3
   4 The following is a consolidated list of the kernel parameters as implemented
   5 (mostly) by the __setup() macro and sorted into English Dictionary order
   6 (defined as ignoring all punctuation and sorting digits before letters in a
   7 case insensitive manner), and with descriptions where known.
   8
   9 Module parameters for loadable modules are specified only as the
  10 parameter name with optional '=' and value as appropriate, such as:
  11
  12         modprobe usbcore blinkenlights=1
  13
  14 Module parameters for modules that are built into the kernel image
  15 are specified on the kernel command line with the module name plus
  16 '.' plus parameter name, with '=' and value if appropriate, such as:
  17
  18         usbcore.blinkenlights=1
  19
  20 The text in square brackets at the beginning of the description state the
  21 restrictions on the kernel for the said kernel parameter to be valid. The
  22 restrictions referred to are that the relevant option is valid if:
  23
  24         ACPI    ACPI support is enabled.
  25         ALSA    ALSA sound support is enabled.
  26         APIC    APIC support is enabled.
  27         APM     Advanced Power Management support is enabled.
  28         AX25    Appropriate AX.25 support is enabled.
  29         CD      Appropriate CD support is enabled.
  30         DEVFS   devfs support is enabled.
  31         DRM     Direct Rendering Management support is enabled.
  32         EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
  33         EFI     EFI Partitioning (GPT) is enabled
  34         EIDE    EIDE/ATAPI support is enabled.
  35         FB      The frame buffer device is enabled.
  36         HW      Appropriate hardware is enabled.
  37         IA-32   IA-32 aka i386 architecture is enabled.
  38         IA-64   IA-64 architecture is enabled.
  39         IOSCHED More than one I/O scheduler is enabled.
  40         IP_PNP  IP DCHP, BOOTP, or RARP is enabled.
  41         ISAPNP  ISA PnP code is enabled.
  42         ISDN    Appropriate ISDN support is enabled.
  43         JOY     Appropriate joystick support is enabled.
  44         LP      Printer support is enabled.
  45         LOOP    Loopback device support is enabled.
  46         M68k    M68k architecture is enabled.
  47                         These options have more detailed description inside of
  48                         Documentation/m68k/kernel-options.txt.
  49         MCA     MCA bus support is enabled.
  50         MDA     MDA console support is enabled.
  51         MOUSE   Appropriate mouse support is enabled.
  52         MTD     MTD support is enabled.
  53         NET     Appropriate network support is enabled.
  54         NUMA    NUMA support is enabled.
  55         NFS     Appropriate NFS support is enabled.
  56         OSS     OSS sound support is enabled.
  57         PARIDE  The ParIDE subsystem is enabled.
  58         PARISC  The PA-RISC architecture is enabled.
  59         PCI     PCI bus support is enabled.
  60         PCMCIA  The PCMCIA subsystem is enabled.
  61         PNP     Plug & Play support is enabled.
  62         PPC     PowerPC architecture is enabled.
  63         PPT     Parallel port support is enabled.
  64         PS2     Appropriate PS/2 support is enabled.
  65         RAM     RAM disk support is enabled.
  66         S390    S390 architecture is enabled.
  67         SCSI    Appropriate SCSI support is enabled.
  68                         A lot of drivers has their options described inside of
  69                         Documentation/scsi/.
  70         SELINUX SELinux support is enabled.
  71         SERIAL  Serial support is enabled.
  72         SMP     The kernel is an SMP kernel.
  73         SPARC   Sparc architecture is enabled.
  74         SWSUSP  Software suspension is enabled.
  75         TS      Appropriate touchscreen support is enabled.
  76         USB     USB support is enabled.
  77         USBHID  USB Human Interface Device support is enabled.
  78         V4L     Video For Linux support is enabled.
  79         VGA     The VGA console has been enabled.
  80         VT      Virtual terminal support is enabled.
  81         WDT     Watchdog support is enabled.
  82         XT      IBM PC/XT MFM hard disk support is enabled.
  83         X86-64  X86-64 architecture is enabled.
  84                         More X86-64 boot options can be found in
  85                         Documentation/x86_64/boot-options.txt .
  86
  87 In addition, the following text indicates that the option:
  88
  89         BUGS=   Relates to possible processor bugs on the said processor.
  90         KNL     Is a kernel start-up parameter.
  91         BOOT    Is a boot loader parameter.
  92
  93 Parameters denoted with BOOT are actually interpreted by the boot
  94 loader, and have no meaning to the kernel directly.
  95 Do not modify the syntax of boot loader parameters without extreme
  96 need or coordination with <Documentation/i386/boot.txt>.
  97
  98 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  99 a trailing = on the name of any parameter states that that parameter will
 100 be entered as an environment variable, whereas its absence indicates that
 101 it will appear as a kernel argument readable via /proc/cmdline by programs
 102 running once the system is up.
 103
 104         53c7xx=         [HW,SCSI] Amiga SCSI controllers
 105                         See header of drivers/scsi/53c7xx.c.
 106                         See also Documentation/scsi/ncr53c7xx.txt.
 107
 108         acpi=           [HW,ACPI] Advanced Configuration and Power Interface
 109                         Format: { force | off | ht | strict }
 110                         force -- enable ACPI if default was off
 111                         off -- disable ACPI if default was on
 112                         noirq -- do not use ACPI for IRQ routing
 113                         ht -- run only enough ACPI to enable Hyper Threading
 114                         strict --  Be less tolerant of platforms that are not
 115                                 strictly ACPI specification compliant.
 116
 117                         See also Documentation/pm.txt, pci=noacpi
 118
 119         acpi_sleep=     [HW,ACPI] Sleep options
 120                         Format: { s3_bios, s3_mode }
 121                         See Documentation/power/video.txt
 122
 123         acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 124                         Format: { level | edge |  high | low }
 125
 126         acpi_irq_balance        [HW,ACPI] ACPI will balance active IRQs
 127                                 default in APIC mode
 128
 129         acpi_irq_nobalance      [HW,ACPI] ACPI will not move active IRQs (default)
 130                                 default in PIC mode
 131
 132         acpi_irq_pci=   [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
 133                         Format: <irq>,<irq>...
 134
 135         acpi_irq_isa=   [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
 136                         Format: <irq>,<irq>...
 137
 138         acpi_osi=       [HW,ACPI] empty param disables _OSI
 139
 140         acpi_serialize  [HW,ACPI] force serialization of AML methods
 141
 142         acpi_skip_timer_override [HW,ACPI]
 143                         Recognize and ignore IRQ0/pin2 Interrupt Override.
 144                         For broken nForce2 BIOS resulting in XT-PIC timer.
 145
 146         acpi_dbg_layer= [HW,ACPI]
 147                         Format: <int>
 148                         Each bit of the <int> indicates an acpi debug layer,
 149                         1: enable, 0: disable. It is useful for boot time
 150                         debugging. After system has booted up, it can be set
 151                         via /proc/acpi/debug_layer.
 152
 153         acpi_dbg_level= [HW,ACPI]
 154                         Format: <int>
 155                         Each bit of the <int> indicates an acpi debug level,
 156                         1: enable, 0: disable. It is useful for boot time
 157                         debugging. After system has booted up, it can be set
 158                         via /proc/acpi/debug_level.
 159
 160         acpi_fake_ecdt  [HW,ACPI] Workaround failure due to BIOS lacking ECDT
 161
 162         ad1816=         [HW,OSS]
 163                         Format: <io>,<irq>,<dma>,<dma2>
 164                         See also Documentation/sound/oss/AD1816.
 165
 166         ad1848=         [HW,OSS]
 167                         Format: <io>,<irq>,<dma>,<dma2>,<type>
 168
 169         adlib=          [HW,OSS]
 170                         Format: <io>
 171
 172         advansys=       [HW,SCSI]
 173                         See header of drivers/scsi/advansys.c.
 174
 175         advwdt=         [HW,WDT] Advantech WDT
 176                         Format: <iostart>,<iostop>
 177
 178         aedsp16=        [HW,OSS] Audio Excel DSP 16
 179                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 180                         See also header of sound/oss/aedsp16.c.
 181
 182         aha152x=        [HW,SCSI]
 183                         See Documentation/scsi/aha152x.txt.
 184
 185         aha1542=        [HW,SCSI]
 186                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 187
 188         aic7xxx=        [HW,SCSI]
 189                         See Documentation/scsi/aic7xxx.txt.
 190
 191         aic79xx=        [HW,SCSI]
 192                         See Documentation/scsi/aic79xx.txt.
 193
 194         AM53C974=       [HW,SCSI]
 195                         Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
 196                         See also header of drivers/scsi/AM53C974.c.
 197
 198         amijoy.map=     [HW,JOY] Amiga joystick support
 199                         Map of devices attached to JOY0DAT and JOY1DAT
 200                         Format: <a>,<b>
 201                         See also Documentation/kernel/input/joystick.txt
 202
 203         analog.map=     [HW,JOY] Analog joystick and gamepad support
 204                         Specifies type or capabilities of an analog joystick
 205                         connected to one of 16 gameports
 206                         Format: <type1>,<type2>,..<type16>
 207
 208         apc=            [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
 209                         Format: noidle
 210                         Disable APC CPU standby support. SPARCstation-Fox does
 211                         not play well with APC CPU idle - disable it if you have
 212                         APC and your system crashes randomly.
 213
 214         apic=           [APIC,i386] Change the output verbosity  whilst booting
 215                         Format: { quiet (default) | verbose | debug }
 216                         Change the amount of debugging information output
 217                         when initialising the APIC and IO-APIC components.
 218
 219         apm=            [APM] Advanced Power Management
 220                         See header of arch/i386/kernel/apm.c.
 221
 222         applicom=       [HW]
 223                         Format: <mem>,<irq>
 224
 225         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 226                         Format: <io>,<irq>,<nodeID>
 227
 228         ataflop=        [HW,M68k]
 229
 230         atarimouse=     [HW,MOUSE] Atari Mouse
 231
 232         atascsi=        [HW,SCSI] Atari SCSI
 233
 234         atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 235                         EzKey and similar keyboards
 236
 237         atkbd.reset=    [HW] Reset keyboard during initialization
 238
 239         atkbd.set=      [HW] Select keyboard code set
 240                         Format: <int> (2 = AT (default) 3 = PS/2)
 241
 242         atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 243                         keyboards
 244
 245         atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 246                         Format: <bool> (0 = real, 1 = synthetic (default))
 247
 248         atkbd.softrepeat=
 249                         [HW] Use software keyboard repeat
 250
 251         autotest        [IA64]
 252
 253         awe=            [HW,OSS] AWE32/SB32/AWE64 wave table synth
 254                         Format: <io>,<memsize>,<isapnp>
 255
 256         aztcd=          [HW,CD] Aztech CD268 CDROM driver
 257                         Format: <io>,0x79 (?)
 258
 259         baycom_epp=     [HW,AX25]
 260                         Format: <io>,<mode>
 261
 262         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 263                         Format: <io>,<mode>
 264                         See header of drivers/net/hamradio/baycom_par.c.
 265
 266         baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 267                         Format: <io>,<irq>,<mode>[,<baud>]
 268                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
 269
 270         baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 271                         Format: <io>,<irq>,<mode>
 272                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 273
 274         blkmtd_device=  [HW,MTD]
 275         blkmtd_erasesz=
 276         blkmtd_ro=
 277         blkmtd_bs=
 278         blkmtd_count=
 279
 280         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 281         bttv.radio=     Most important insmod options are available as kernel args too.
 282         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 283         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 284
 285         BusLogic=       [HW,SCSI]
 286                         See drivers/scsi/BusLogic.c, comment before function
 287                         BusLogic_ParseDriverOptions().
 288
 289         c101=           [NET] Moxa C101 synchronous serial card
 290
 291         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
 292                         Sometimes CPU hardware bugs make them report the cache
 293                         size incorrectly. The kernel will attempt work arounds
 294                         to fix known problems, but for some CPUs it is not
 295                         possible to determine what the correct size should be.
 296                         This option provides an override for these situations.
 297
 298         cdu31a=         [HW,CD]
 299                         Format: <io>,<irq>[,PAS]
 300                         See header of drivers/cdrom/cdu31a.c.
 301
 302         chandev=        [HW,NET] Generic channel device initialisation
 303
 304         checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 305                         Format: { "0" | "1" }
 306                         See security/selinux/Kconfig help text.
 307                         0 -- check protection applied by kernel (includes any implied execute protection).
 308                         1 -- check protection requested by application.
 309                         Default value is set via a kernel config option.
 310                         Value can be changed at runtime via /selinux/checkreqprot.
 311
 312         clock=          [BUGS=IA-32, HW] gettimeofday timesource override.
 313                         Forces specified timesource (if avaliable) to be used
 314                         when calculating gettimeofday(). If specicified timesource
 315                         is not avalible, it defaults to PIT.
 316                         Format: { pit | tsc | cyclone | pmtmr }
 317
 318         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
 319                         Format: disable
 320
 321         cm206=          [HW,CD]
 322                         Format: { auto | [<io>,][<irq>] }
 323
 324         com20020=       [HW,NET] ARCnet - COM20020 chipset
 325                         Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 326
 327         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 328                         Format: <io>[,<irq>]
 329
 330         com90xx=        [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
 331                         Format: <io>[,<irq>[,<memstart>]]
 332
 333         condev=         [HW,S390] console device
 334         conmode=
 335
 336         console=        [KNL] Output console device and options.
 337
 338                 tty<n>  Use the virtual console device <n>.
 339
 340                 ttyS<n>[,options]
 341                         Use the specified serial port.  The options are of
 342                         the form "bbbbpn", where "bbbb" is the baud rate,
 343                         "p" is parity ("n", "o", or "e"), and "n" is bits.
 344                         Default is "9600n8".
 345
 346                         See also Documentation/serial-console.txt.
 347
 348                 uart,io,<addr>[,options]
 349                 uart,mmio,<addr>[,options]
 350                         Start an early, polled-mode console on the 8250/16550
 351                         UART at the specified I/O port or MMIO address,
 352                         switching to the matching ttyS device later.  The
 353                         options are the same as for ttyS, above.
 354
 355         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 356                         Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 357
 358         cpia_pp=        [HW,PPT]
 359                         Format: { parport<nr> | auto | none }
 360
 361         crashkernel=nn[KMG]@ss[KMG]
 362                         [KNL] Reserve a chunk of physical memory to
 363                         hold a kernel to switch to with kexec on panic.
 364
 365         cs4232=         [HW,OSS]
 366                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
 367
 368         cs89x0_dma=     [HW,NET]
 369                         Format: <dma>
 370
 371         cs89x0_media=   [HW,NET]
 372                         Format: { rj45 | aui | bnc }
 373
 374         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
 375
 376         dasd=           [HW,NET]
 377                         See header of drivers/s390/block/dasd_devmap.c.
 378
 379         db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 380                         (one device per port)
 381                         Format: <port#>,<type>
 382                         See also Documentation/input/joystick-parport.txt
 383
 384         debug           [KNL] Enable kernel debugging (events log level).
 385
 386         decnet=         [HW,NET]
 387                         Format: <area>[,<node>]
 388                         See also Documentation/networking/decnet.txt.
 389
 390         devfs=          [DEVFS]
 391                         See Documentation/filesystems/devfs/boot-options.
 392
 393         dhash_entries=  [KNL]
 394                         Set number of hash buckets for dentry cache.
 395
 396         digi=           [HW,SERIAL]
 397                         IO parameters + enable/disable command.
 398
 399         digiepca=       [HW,SERIAL]
 400                         See drivers/char/README.epca and
 401                         Documentation/digiepca.txt.
 402
 403         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
 404                         support available.
 405                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
 406
 407         dmasound=       [HW,OSS] Sound subsystem buffers
 408
 409         dscc4.setup=    [NET]
 410
 411         dtc3181e=       [HW,SCSI]
 412
 413         earlyprintk=    [IA-32, X86-64]
 414                         earlyprintk=vga
 415                         earlyprintk=serial[,ttySn[,baudrate]]
 416
 417                         Append ,keep to not disable it when the real console
 418                         takes over.
 419
 420                         Only vga or serial at a time, not both.
 421
 422                         Currently only ttyS0 and ttyS1 are supported.
 423
 424                         Interaction with the standard serial driver is not
 425                         very good.
 426
 427                         The VGA output is eventually overwritten by the real
 428                         console.
 429
 430         eata=           [HW,SCSI]
 431
 432         eda=            [HW,PS2]
 433
 434         edb=            [HW,PS2]
 435
 436         edd=            [EDD]
 437                         Format: {"of[f]" | "sk[ipmbr]"}
 438                         See comment in arch/i386/boot/edd.S
 439
 440         eicon=          [HW,ISDN]
 441                         Format: <id>,<membase>,<irq>
 442
 443         eisa_irq_edge=  [PARISC,HW]
 444                         See header of drivers/parisc/eisa.c.
 445
 446         elanfreq=       [IA-32]
 447                         See comment before function elanfreq_setup() in
 448                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
 449
 450         elevator=       [IOSCHED]
 451                         Format: {"as"|"cfq"|"deadline"|"noop"}
 452                         See Documentation/block/as-iosched.txt
 453                         and Documentation/block/deadline-iosched.txt for details.
 454         elfcorehdr=     [IA-32]
 455                         Specifies physical address of start of kernel core image
 456                         elf header.
 457                         See Documentation/kdump.txt for details.
 458
 459         enforcing       [SELINUX] Set initial enforcing status.
 460                         Format: {"0" | "1"}
 461                         See security/selinux/Kconfig help text.
 462                         0 -- permissive (log only, no denials).
 463                         1 -- enforcing (deny and log).
 464                         Default value is 0.
 465                         Value can be changed at runtime via /selinux/enforce.
 466
 467         es1370=         [HW,OSS]
 468                         Format: <lineout>[,<micbias>]
 469                         See also header of sound/oss/es1370.c.
 470
 471         es1371=         [HW,OSS]
 472                         Format: <spdif>,[<nomix>,[<amplifier>]]
 473                         See also header of sound/oss/es1371.c.
 474
 475         ether=          [HW,NET] Ethernet cards parameters
 476                         This option is obsoleted by the "netdev=" option, which
 477                         has equivalent usage. See its documentation for details.
 478
 479         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 480                         Format: <io>[,<irq>]
 481
 482         fd_mcs=         [HW,SCSI]
 483                         See header of drivers/scsi/fd_mcs.c.
 484
 485         fdomain=        [HW,SCSI]
 486                         See header of drivers/scsi/fdomain.c.
 487
 488         floppy=         [HW]
 489                         See Documentation/floppy.txt.
 490
 491         ftape=          [HW] Floppy Tape subsystem debugging options.
 492                         See Documentation/ftape.txt.
 493
 494         gamecon.map[2|3]=
 495                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 496                         support via parallel port (up to 5 devices per port)
 497                         Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 498                         See also Documentation/input/joystick-parport.txt
 499
 500         gamma=          [HW,DRM]
 501
 502         gdth=           [HW,SCSI]
 503                         See header of drivers/scsi/gdth.c.
 504
 505         gpt             [EFI] Forces disk with valid GPT signature but
 506                         invalid Protective MBR to be treated as GPT.
 507
 508         gscd=           [HW,CD]
 509                         Format: <io>
 510
 511         gt96100eth=     [NET] MIPS GT96100 Advanced Communication Controller
 512
 513         gus=            [HW,OSS]
 514                         Format: <io>,<irq>,<dma>,<dma16>
 515
 516         gvp11=          [HW,SCSI]
 517
 518         hashdist=       [KNL,NUMA] Large hashes allocated during boot
 519                         are distributed across NUMA nodes.  Defaults on
 520                         for IA-64, off otherwise.
 521
 522         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 523
 524         hd=             [EIDE] (E)IDE hard drive subsystem geometry
 525                         Format: <cyl>,<head>,<sect>
 526
 527         hd?=            [HW] (E)IDE subsystem
 528         hd?lun=         See Documentation/ide.txt.
 529
 530         highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 531                         size of <nn>. This works even on boxes that have no
 532                         highmem otherwise. This also works to reduce highmem
 533                         size on bigger boxes.
 534
 535         hisax=          [HW,ISDN]
 536                         See Documentation/isdn/README.HiSax.
 537
 538         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
 539
 540         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
 541
 542         i8042.direct    [HW] Put keyboard port into non-translated mode
 543         i8042.dumbkbd   [HW] Pretend that controlled can only read data from
 544                              keyboard and can not control its state
 545                              (Don't attempt to blink the leds)
 546         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 547         i8042.nomux     [HW] Don't check presence of an active multiplexing
 548                              controller
 549         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 550                              controllers
 551         i8042.panicblink=
 552                         [HW] Frequency with which keyboard LEDs should blink
 553                              when kernel panics (default is 0.5 sec)
 554         i8042.reset     [HW] Reset the controller during init and cleanup
 555         i8042.unlock    [HW] Unlock (ignore) the keylock
 556
 557         i810=           [HW,DRM]
 558
 559         i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 560                         indicates that the driver is running on unsupported
 561                         hardware.
 562         i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 563                         does not match list of supported models.
 564         i8k.power_status
 565                         [HW] Report power status in /proc/i8k
 566                         (disabled by default)
 567         i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 568                         capability is set.
 569
 570         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 571                         See Documentation/mca.txt.
 572
 573         icn=            [HW,ISDN]
 574                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 575
 576         ide=            [HW] (E)IDE subsystem
 577                         Format: ide=nodma or ide=doubler or ide=reverse
 578                         See Documentation/ide.txt.
 579
 580         ide?=           [HW] (E)IDE subsystem
 581                         Format: ide?=noprobe or chipset specific parameters.
 582                         See Documentation/ide.txt.
 583
 584         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
 585                         See Documentation/ide.txt.
 586
 587         idle=           [HW]
 588                         Format: idle=poll or idle=halt
 589
 590         ihash_entries=  [KNL]
 591                         Set number of hash buckets for inode cache.
 592
 593         in2000=         [HW,SCSI]
 594                         See header of drivers/scsi/in2000.c.
 595
 596         init=           [KNL]
 597                         Format: <full_path>
 598                         Run specified binary instead of /sbin/init as init
 599                         process.
 600
 601         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 602                         for working out where the kernel is dying during
 603                         startup.
 604
 605         initrd=         [BOOT] Specify the location of the initial ramdisk
 606
 607         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 608                         Format: <irq>
 609
 610         inttest=        [IA64]
 611
 612         io7=            [HW] IO7 for Marvel based alpha systems
 613                         See comment before marvel_specify_io7 in
 614                         arch/alpha/kernel/core_marvel.c.
 615
 616         ip=             [IP_PNP]
 617                         See Documentation/nfsroot.txt.
 618
 619         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
 620                         See comment before ip2_setup() in drivers/char/ip2.c.
 621
 622         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
 623                         See header of drivers/scsi/ips.c.
 624
 625         irqfixup        [HW]
 626                         When an interrupt is not handled search all handlers
 627                         for it. Intended to get systems with badly broken
 628                         firmware running.
 629
 630         irqpoll         [HW]
 631                         When an interrupt is not handled search all handlers
 632                         for it. Also check all handlers each timer
 633                         interrupt. Intended to get systems with badly broken
 634                         firmware running.
 635
 636         isapnp=         [ISAPNP]
 637                         Format: <RDP>, <reset>, <pci_scan>, <verbosity>
 638
 639         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
 640                         Format: <cpu number>,...,<cpu number>
 641                         This option can be used to specify one or more CPUs
 642                         to isolate from the general SMP balancing and scheduling
 643                         algorithms. The only way to move a process onto or off
 644                         an "isolated" CPU is via the CPU affinity syscalls.
 645                         <cpu number> begins at 0 and the maximum value is
 646                         "number of CPUs in system - 1".
 647
 648                         This option is the preferred way to isolate CPUs. The
 649                         alternative - manually setting the CPU mask of all tasks
 650                         in the system can cause problems and suboptimal load
 651                         balancer performance.
 652
 653         isp16=          [HW,CD]
 654                         Format: <io>,<irq>,<dma>,<setup>
 655
 656         iucv=           [HW,NET]
 657
 658         js=             [HW,JOY] Analog joystick
 659                         See Documentation/input/joystick.txt.
 660
 661         keepinitrd      [HW,ARM]
 662
 663         kstack=N        [IA-32, X86-64] Print N words from the kernel stack
 664                         in oops dumps.
 665
 666         l2cr=           [PPC]
 667
 668         lapic           [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
 669
 670         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
 671                         Format: addr:<io>,irq:<irq>
 672
 673         llsc*=          [IA64]
 674                         See function print_params() in arch/ia64/sn/kernel/llsc4.c.
 675
 676         load_ramdisk=   [RAM] List of ramdisks to load from floppy
 677                         See Documentation/ramdisk.txt.
 678
 679         lockd.udpport=  [NFS]
 680
 681         lockd.tcpport=  [NFS]
 682
 683         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
 684                         Format: <irq>
 685
 686         loglevel=       All Kernel Messages with a loglevel smaller than the
 687                         console loglevel will be printed to the console. It can
 688                         also be changed with klogd or other programs. The
 689                         loglevels are defined as follows:
 690
 691                         0 (KERN_EMERG)          system is unusable
 692                         1 (KERN_ALERT)          action must be taken immediately
 693                         2 (KERN_CRIT)           critical conditions
 694                         3 (KERN_ERR)            error conditions
 695                         4 (KERN_WARNING)        warning conditions
 696                         5 (KERN_NOTICE)         normal but significant condition
 697                         6 (KERN_INFO)           informational
 698                         7 (KERN_DEBUG)          debug-level messages
 699
 700         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
 701                         Format is n, nk, nM.  n must be a power of two.  The
 702                         default is set in kernel config.
 703
 704         lp=0            [LP]    Specify parallel ports to use, e.g,
 705         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
 706         lp=reset                first parallel port). 'lp=0' disables the
 707         lp=auto                 printer driver. 'lp=reset' (which can be
 708                                 specified in addition to the ports) causes
 709                                 attached printers to be reset. Using
 710                                 lp=port1,port2,... specifies the parallel ports
 711                                 to associate lp devices with, starting with
 712                                 lp0. A port specification may be 'none' to skip
 713                                 that lp device, or a parport name such as
 714                                 'parport0'. Specifying 'lp=auto' instead of a
 715                                 port specification list means that device IDs
 716                                 from each port should be examined, to see if
 717                                 an IEEE 1284-compliant printer is attached; if
 718                                 so, the driver will manage that printer.
 719                                 See also header of drivers/char/lp.c.
 720
 721         lpj=n           [KNL]
 722                         Sets loops_per_jiffy to given constant, thus avoiding
 723                         time-consuming boot-time autodetection (up to 250 ms per
 724                         CPU). 0 enables autodetection (default). To determine
 725                         the correct value for your kernel, boot with normal
 726                         autodetection and see what value is printed. Note that
 727                         on SMP systems the preset will be applied to all CPUs,
 728                         which is likely to cause problems if your CPUs need
 729                         significantly divergent settings. An incorrect value
 730                         will cause delays in the kernel to be wrong, leading to
 731                         unpredictable I/O errors and other breakage. Although
 732                         unlikely, in the extreme case this might damage your
 733                         hardware.
 734
 735         ltpc=           [NET]
 736                         Format: <io>,<irq>,<dma>
 737
 738         mac5380=        [HW,SCSI]
 739                         Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 740
 741         mac53c9x=       [HW,SCSI]
 742                         Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
 743
 744         machvec=        [IA64]
 745                         Force the use of a particular machine-vector (machvec) in a generic
 746                         kernel.  Example: machvec=hpzx1_swiotlb
 747
 748         mad16=          [HW,OSS]
 749                         Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
 750
 751         maui=           [HW,OSS]
 752                         Format: <io>,<irq>
 753
 754         max_loop=       [LOOP] Maximum number of loopback devices that can
 755                         be mounted
 756                         Format: <1-256>
 757
 758         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
 759                         should make use of
 760
 761         max_luns=       [SCSI] Maximum number of LUNs to probe
 762                         Should be between 1 and 2^32-1.
 763
 764         max_report_luns=
 765                         [SCSI] Maximum number of LUNs received
 766                         Should be between 1 and 16384.
 767
 768         mca-pentium     [BUGS=IA-32]
 769
 770         mcatest=        [IA-64]
 771
 772         mcd=            [HW,CD]
 773                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
 774
 775         mcdx=           [HW,CD]
 776
 777         mce             [IA-32] Machine Check Exception
 778
 779         md=             [HW] RAID subsystems devices and level
 780                         See Documentation/md.txt.
 781
 782         mdacon=         [MDA]
 783                         Format: <first>,<last>
 784                         Specifies range of consoles to be captured by the MDA.
 785
 786         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
 787                         Amount of memory to be used when the kernel is not able
 788                         to see the whole system memory or for test.
 789                         [IA-32] Use together with memmap= to avoid physical
 790                         address space collisions. Without memmap= PCI devices
 791                         could be placed at addresses belonging to unused RAM.
 792
 793         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
 794                         memory.
 795
 796         memmap=exactmap [KNL,IA-32] Enable setting of an exact
 797                         E820 memory map, as specified by the user.
 798                         Such memmap=exactmap lines can be constructed based on
 799                         BIOS output or other requirements. See the memmap=nn@ss
 800                         option description.
 801
 802         memmap=nn[KMG]@ss[KMG]
 803                         [KNL] Force usage of a specific region of memory
 804                         Region of memory to be used, from ss to ss+nn.
 805
 806         memmap=nn[KMG]#ss[KMG]
 807                         [KNL,ACPI] Mark specific memory as ACPI data.
 808                         Region of memory to be used, from ss to ss+nn.
 809
 810         memmap=nn[KMG]$ss[KMG]
 811                         [KNL,ACPI] Mark specific memory as reserved.
 812                         Region of memory to be used, from ss to ss+nn.
 813
 814         meye.*=         [HW] Set MotionEye Camera parameters
 815                         See Documentation/video4linux/meye.txt.
 816
 817         mga=            [HW,DRM]
 818
 819         mousedev.tap_time=
 820                         [MOUSE] Maximum time between finger touching and
 821                         leaving touchpad surface for touch to be considered
 822                         a tap and be reported as a left button click (for
 823                         touchpads working in absolute mode only).
 824                         Format: <msecs>
 825         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
 826                         reporting absolute coordinates, such as tablets
 827         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
 828                         reporting absolute coordinates, such as tablets
 829
 830         mpu401=         [HW,OSS]
 831                         Format: <io>,<irq>
 832
 833         MTD_Partition=  [MTD]
 834                         Format: <name>,<region-number>,<size>,<offset>
 835
 836         MTD_Region=     [MTD]
 837                         Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
 838
 839         mtdparts=       [MTD]
 840                         See drivers/mtd/cmdline.c.
 841
 842         mtouchusb.raw_coordinates=
 843                         [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
 844                         or cooked coordinates ('n')
 845
 846         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
 847
 848         NCR_D700=       [HW,SCSI]
 849                         See header of drivers/scsi/NCR_D700.c.
 850
 851         ncr5380=        [HW,SCSI]
 852
 853         ncr53c400=      [HW,SCSI]
 854
 855         ncr53c400a=     [HW,SCSI]
 856
 857         ncr53c406a=     [HW,SCSI]
 858
 859         ncr53c8xx=      [HW,SCSI]
 860
 861         netdev=         [NET] Network devices parameters
 862                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
 863                         Note that mem_start is often overloaded to mean
 864                         something different and driver-specific.
 865
 866         nfsaddrs=       [NFS]
 867                         See Documentation/nfsroot.txt.
 868
 869         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
 870                         See Documentation/nfsroot.txt.
 871
 872         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
 873
 874         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
 875                         emulation library even if a 387 maths coprocessor
 876                         is present.
 877
 878         noalign         [KNL,ARM]
 879
 880         noapic          [SMP,APIC] Tells the kernel to not make use of any
 881                         IOAPICs that may be present in the system.
 882
 883         noasync         [HW,M68K] Disables async and sync negotiation for
 884                         all devices.
 885
 886         nobats          [PPC] Do not use BATs for mapping kernel lowmem
 887                         on "Classic" PPC cores.
 888
 889         nocache         [ARM]
 890
 891         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
 892
 893         noexec          [IA-64]
 894
 895         noexec          [IA-32, X86-64]
 896                         noexec=on: enable non-executable mappings (default)
 897                         noexec=off: disable nn-executable mappings
 898
 899         nofxsr          [BUGS=IA-32]
 900
 901         nohlt           [BUGS=ARM]
 902
 903         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
 904                         instruction doesn't work correctly and not to
 905                         use it.
 906
 907         nohalt          [IA-64] Tells the kernel not to use the power saving
 908                         function PAL_HALT_LIGHT when idle. This increases
 909                         power-consumption. On the positive side, it reduces
 910                         interrupt wake-up latency, which may improve performance
 911                         in certain environments such as networked servers or
 912                         real-time systems.
 913
 914         noirqdebug      [IA-32] Disables the code which attempts to detect and
 915                         disable unhandled interrupt sources.
 916
 917         noisapnp        [ISAPNP] Disables ISA PnP code.
 918
 919         noinitrd        [RAM] Tells the kernel not to load any configured
 920                         initial RAM disk.
 921
 922         nointroute      [IA-64]
 923
 924         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 925
 926         noltlbs         [PPC] Do not use large page/tlb entries for kernel
 927                         lowmem mapping on PPC40x.
 928
 929         nomce           [IA-32] Machine Check Exception
 930
 931         noresidual      [PPC] Don't use residual data on PReP machines.
 932
 933         noresume        [SWSUSP] Disables resume and restore original swap space.
 934
 935         no-scroll       [VGA] Disables scrollback.
 936                         This is required for the Braillex ib80-piezo Braille
 937                         reader made by F.H. Papenmeier (Germany).
 938
 939         nosbagart       [IA-64]
 940
 941         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
 942
 943         nosync          [HW,M68K] Disables sync negotiation for all devices.
 944
 945         notsc           [BUGS=IA-32] Disable Time Stamp Counter
 946
 947         nousb           [USB] Disable the USB subsystem
 948
 949         nowb            [ARM]
 950
 951         opl3=           [HW,OSS]
 952                         Format: <io>
 953
 954         opl3sa=         [HW,OSS]
 955                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
 956
 957         opl3sa2=        [HW,OSS]
 958                         Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
 959
 960         oprofile.timer= [HW]
 961                         Use timer interrupt instead of performance counters
 962
 963         optcd=          [HW,CD]
 964                         Format: <io>
 965
 966         osst=           [HW,SCSI] SCSI Tape Driver
 967                         Format: <buffer_size>,<write_threshold>
 968                         See also Documentation/scsi/st.txt.
 969
 970         panic=          [KNL] Kernel behaviour on panic
 971                         Format: <timeout>
 972
 973         parkbd.port=    [HW] Parallel port number the keyboard adapter is
 974                         connected to, default is 0.
 975                         Format: <parport#>
 976         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
 977                         0 for XT, 1 for AT (default is AT).
 978                         Format: <mode>
 979
 980         parport=0       [HW,PPT]        Specify parallel ports. 0 disables.
 981         parport=auto                    Use 'auto' to force the driver to use
 982         parport=0xBBB[,IRQ[,DMA]]       any IRQ/DMA settings detected (the
 983                                         default is to ignore detected IRQ/DMA
 984                                         settings because of possible
 985                                         conflicts). You can specify the base
 986                                         address, IRQ, and DMA settings; IRQ and
 987                                         DMA should be numbers, or 'auto' (for
 988                                         using detected settings on that
 989                                         particular port), or 'nofifo' (to avoid
 990                                         using a FIFO even if it is detected).
 991                                         Parallel ports are assigned in the
 992                                         order they are specified on the command
 993                                         line, starting with parport0.
 994
 995         parport_init_mode=
 996                         [HW,PPT]        Configure VIA parallel port to
 997                                         operate in specific mode. This is
 998                                         necessary on Pegasos computer where
 999                                         firmware has no options for setting up
1000                                         parallel port mode and sets it to
1001                                         spp. Currently this function knows
1002                                         686a and 8231 chips.
1003                         Format: [spp|ps2|epp|ecp|ecpepp]
1004
1005         pas2=           [HW,OSS]
1006                         Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1007
1008         pas16=          [HW,SCSI]
1009                         See header of drivers/scsi/pas16.c.
1010
1011         pcbit=          [HW,ISDN]
1012
1013         pcd.            [PARIDE]
1014                         See header of drivers/block/paride/pcd.c.
1015                         See also Documentation/paride.txt.
1016
1017         pci=option[,option...]          [PCI] various PCI subsystem options:
1018                 off                     [IA-32] don't probe for the PCI bus
1019                 bios                    [IA-32] force use of PCI BIOS, don't access
1020                                         the hardware directly. Use this if your machine
1021                                         has a non-standard PCI host bridge.
1022                 nobios                  [IA-32] disallow use of PCI BIOS, only direct
1023                                         hardware access methods are allowed. Use this
1024                                         if you experience crashes upon bootup and you
1025                                         suspect they are caused by the BIOS.
1026                 conf1                   [IA-32] Force use of PCI Configuration Mechanism 1.
1027                 conf2                   [IA-32] Force use of PCI Configuration Mechanism 2.
1028                 nosort                  [IA-32] Don't sort PCI devices according to
1029                                         order given by the PCI BIOS. This sorting is done
1030                                         to get a device order compatible with older kernels.
1031                 biosirq                 [IA-32] Use PCI BIOS calls to get the interrupt
1032                                         routing table. These calls are known to be buggy
1033                                         on several machines and they hang the machine when used,
1034                                         but on other computers it's the only way to get the
1035                                         interrupt routing table. Try this option if the kernel
1036                                         is unable to allocate IRQs or discover secondary PCI
1037                                         buses on your motherboard.
1038                 rom                     [IA-32] Assign address space to expansion ROMs.
1039                                         Use with caution as certain devices share address
1040                                         decoders between ROMs and other resources.
1041                 irqmask=0xMMMM          [IA-32] Set a bit mask of IRQs allowed to be assigned
1042                                         automatically to PCI devices. You can make the kernel
1043                                         exclude IRQs of your ISA cards this way.
1044                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1045                                         of the PIRQ table (normally generated
1046                                         by the BIOS) if it is outside the
1047                                         F0000h-100000h range.
1048                 lastbus=N               [IA-32] Scan all buses till bus #N. Can be useful
1049                                         if the kernel is unable to find your secondary buses
1050                                         and you want to tell it explicitly which ones they are.
1051                 assign-busses           [IA-32] Always assign all PCI bus
1052                                         numbers ourselves, overriding
1053                                         whatever the firmware may have
1054                                         done.
1055                 usepirqmask             [IA-32] Honor the possible IRQ mask
1056                                         stored in the BIOS $PIR table. This is
1057                                         needed on some systems with broken
1058                                         BIOSes, notably some HP Pavilion N5400
1059                                         and Omnibook XE3 notebooks. This will
1060                                         have no effect if ACPI IRQ routing is
1061                                         enabled.
1062                 noacpi                  [IA-32] Do not use ACPI for IRQ routing
1063                                         or for PCI scanning.
1064                 routeirq                Do IRQ routing for all PCI devices.
1065                                         This is normally done in pci_enable_device(),
1066                                         so this option is a temporary workaround
1067                                         for broken drivers that don't call it.
1068
1069                 firmware                [ARM] Do not re-enumerate the bus but
1070                                         instead just use the configuration
1071                                         from the bootloader. This is currently
1072                                         used on IXP2000 systems where the
1073                                         bus has to be configured a certain way
1074                                         for adjunct CPUs.
1075
1076         pcmv=           [HW,PCMCIA] BadgePAD 4
1077
1078         pd.             [PARIDE]
1079                         See Documentation/paride.txt.
1080
1081         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1082                         boot time.
1083                         Format: { 0 | 1 }
1084                         See arch/parisc/kernel/pdc_chassis.c
1085
1086         pf.             [PARIDE]
1087                         See Documentation/paride.txt.
1088
1089         pg.             [PARIDE]
1090                         See Documentation/paride.txt.
1091
1092         pirq=           [SMP,APIC] Manual mp-table setup
1093                         See Documentation/i386/IO-APIC.txt.
1094
1095         plip=           [PPT,NET] Parallel port network link
1096                         Format: { parport<nr> | timid | 0 }
1097                         See also Documentation/parport.txt.
1098
1099         pnpacpi=        [ACPI]
1100                         { off }
1101
1102         pnpbios=        [ISAPNP]
1103                         { on | off | curr | res | no-curr | no-res }
1104
1105         pnp_reserve_irq=
1106                         [ISAPNP] Exclude IRQs for the autoconfiguration
1107
1108         pnp_reserve_dma=
1109                         [ISAPNP] Exclude DMAs for the autoconfiguration
1110
1111         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1112                         Ranges are in pairs (I/O port base and size).
1113
1114         pnp_reserve_mem=
1115                         [ISAPNP] Exclude memory regions for the autoconfiguration
1116                         Ranges are in pairs (memory base and size).
1117
1118         profile=        [KNL] Enable kernel profiling via /proc/profile
1119                         { schedule | <number> }
1120                         (param: schedule - profile schedule points}
1121                         (param: profile step/bucket size as a power of 2 for
1122                                 statistical time based profiling)
1123
1124         processor.max_cstate=   [HW, ACPI]
1125                         Limit processor to maximum C-state
1126                         max_cstate=9 overrides any DMI blacklist limit.
1127
1128         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1129                         before loading.
1130                         See Documentation/ramdisk.txt.
1131
1132         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1133                         probe for (bare|imps|exps|lifebook|any).
1134         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1135                         per second.
1136         psmouse.resetafter=
1137                         [HW,MOUSE] Try to reset the device after so many bad packets
1138                         (0 = never).
1139         psmouse.resolution=
1140                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1141         psmouse.smartscroll=
1142                         [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1143                         0 = disabled, 1 = enabled (default).
1144
1145         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1146                         Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1147
1148         pt.             [PARIDE]
1149                         See Documentation/paride.txt.
1150
1151         quiet=          [KNL] Disable log messages
1152
1153         r128=           [HW,DRM]
1154
1155         raid=           [HW,RAID]
1156                         See Documentation/md.txt.
1157
1158         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1159                         See Documentation/ramdisk.txt.
1160
1161         ramdisk_blocksize=
1162                         [RAM]
1163                         See Documentation/ramdisk.txt.
1164
1165         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1166                         New name for the ramdisk parameter.
1167                         See Documentation/ramdisk.txt.
1168
1169         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1170                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1171                         See arch/*/kernel/reboot.c.
1172
1173         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1174
1175         resume=         [SWSUSP] Specify the partition device for software suspension
1176
1177         rhash_entries=  [KNL,NET]
1178                         Set number of hash buckets for route cache
1179
1180         riscom8=        [HW,SERIAL]
1181                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1182
1183         ro              [KNL] Mount root device read-only on boot
1184
1185         root=           [KNL] Root filesystem
1186
1187         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1188                         mount the root filesystem
1189
1190         rootflags=      [KNL] Set root filesystem mount option string
1191
1192         rootfstype=     [KNL] Set root filesystem type
1193
1194         rw              [KNL] Mount root device read-write on boot
1195
1196         S               [KNL] Run init in single mode
1197
1198         sa1100ir        [NET]
1199                         See drivers/net/irda/sa1100_ir.c.
1200
1201         sb=             [HW,OSS]
1202                         Format: <io>,<irq>,<dma>,<dma2>
1203
1204         sbni=           [NET] Granch SBNI12 leased line adapter
1205
1206         sbpcd=          [HW,CD] Soundblaster CD adapter
1207                         Format: <io>,<type>
1208                         See a comment before function sbpcd_setup() in
1209                         drivers/cdrom/sbpcd.c.
1210
1211         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1212                         Format: <io>[,<timeout>[,<isapnp>]]
1213
1214         scsi_debug_*=   [SCSI]
1215                         See drivers/scsi/scsi_debug.c.
1216
1217         scsi_default_dev_flags=
1218                         [SCSI] SCSI default device flags
1219                         Format: <integer>
1220
1221         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1222                         Format: <vendor>:<model>:<flags>
1223                         (flags are integer value)
1224
1225         scsi_logging=   [SCSI]
1226
1227         selinux         [SELINUX] Disable or enable SELinux at boot time.
1228                         Format: { "0" | "1" }
1229                         See security/selinux/Kconfig help text.
1230                         0 -- disable.
1231                         1 -- enable.
1232                         Default value is set via kernel config option.
1233                         If enabled at boot time, /selinux/disable can be used
1234                         later to disable prior to initial policy load.
1235
1236         serialnumber    [BUGS=IA-32]
1237
1238         sg_def_reserved_size=
1239                         [SCSI]
1240
1241         sgalaxy=        [HW,OSS]
1242                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1243
1244         shapers=        [NET]
1245                         Maximal number of shapers.
1246
1247         sim710=         [SCSI,HW]
1248                         See header of drivers/scsi/sim710.c.
1249
1250         simeth=         [IA-64]
1251         simscsi=
1252
1253         sjcd=           [HW,CD]
1254                         Format: <io>,<irq>,<dma>
1255                         See header of drivers/cdrom/sjcd.c.
1256
1257         slram=          [HW,MTD]
1258
1259         smart2=         [HW]
1260                         Format: <io1>[,<io2>[,...,<io8>]]
1261
1262         snd-ad1816a=    [HW,ALSA]
1263
1264         snd-ad1848=     [HW,ALSA]
1265
1266         snd-ali5451=    [HW,ALSA]
1267
1268         snd-als100=     [HW,ALSA]
1269
1270         snd-als4000=    [HW,ALSA]
1271
1272         snd-azt2320=    [HW,ALSA]
1273
1274         snd-cmi8330=    [HW,ALSA]
1275
1276         snd-cmipci=     [HW,ALSA]
1277
1278         snd-cs4231=     [HW,ALSA]
1279
1280         snd-cs4232=     [HW,ALSA]
1281
1282         snd-cs4236=     [HW,ALSA]
1283
1284         snd-cs4281=     [HW,ALSA]
1285
1286         snd-cs46xx=     [HW,ALSA]
1287
1288         snd-dt019x=     [HW,ALSA]
1289
1290         snd-dummy=      [HW,ALSA]
1291
1292         snd-emu10k1=    [HW,ALSA]
1293
1294         snd-ens1370=    [HW,ALSA]
1295
1296         snd-ens1371=    [HW,ALSA]
1297
1298         snd-es968=      [HW,ALSA]
1299
1300         snd-es1688=     [HW,ALSA]
1301
1302         snd-es18xx=     [HW,ALSA]
1303
1304         snd-es1938=     [HW,ALSA]
1305
1306         snd-es1968=     [HW,ALSA]
1307
1308         snd-fm801=      [HW,ALSA]
1309
1310         snd-gusclassic= [HW,ALSA]
1311
1312         snd-gusextreme= [HW,ALSA]
1313
1314         snd-gusmax=     [HW,ALSA]
1315
1316         snd-hdsp=       [HW,ALSA]
1317
1318         snd-ice1712=    [HW,ALSA]
1319
1320         snd-intel8x0=   [HW,ALSA]
1321
1322         snd-interwave=  [HW,ALSA]
1323
1324         snd-interwave-stb=
1325                         [HW,ALSA]
1326
1327         snd-korg1212=   [HW,ALSA]
1328
1329         snd-maestro3=   [HW,ALSA]
1330
1331         snd-mpu401=     [HW,ALSA]
1332
1333         snd-mtpav=      [HW,ALSA]
1334
1335         snd-nm256=      [HW,ALSA]
1336
1337         snd-opl3sa2=    [HW,ALSA]
1338
1339         snd-opti92x-ad1848=
1340                         [HW,ALSA]
1341
1342         snd-opti92x-cs4231=
1343                         [HW,ALSA]
1344
1345         snd-opti93x=    [HW,ALSA]
1346
1347         snd-pmac=       [HW,ALSA]
1348
1349         snd-rme32=      [HW,ALSA]
1350
1351         snd-rme96=      [HW,ALSA]
1352
1353         snd-rme9652=    [HW,ALSA]
1354
1355         snd-sb8=        [HW,ALSA]
1356
1357         snd-sb16=       [HW,ALSA]
1358
1359         snd-sbawe=      [HW,ALSA]
1360
1361         snd-serial=     [HW,ALSA]
1362
1363         snd-sgalaxy=    [HW,ALSA]
1364
1365         snd-sonicvibes= [HW,ALSA]
1366
1367         snd-sun-amd7930=
1368                         [HW,ALSA]
1369
1370         snd-sun-cs4231= [HW,ALSA]
1371
1372         snd-trident=    [HW,ALSA]
1373
1374         snd-usb-audio=  [HW,ALSA,USB]
1375
1376         snd-via82xx=    [HW,ALSA]
1377
1378         snd-virmidi=    [HW,ALSA]
1379
1380         snd-wavefront=  [HW,ALSA]
1381
1382         snd-ymfpci=     [HW,ALSA]
1383
1384         sonicvibes=     [HW,OSS]
1385                         Format: <reverb>
1386
1387         sonycd535=      [HW,CD]
1388                         Format: <io>[,<irq>]
1389
1390         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1391                         See Documentation/sonypi.txt
1392
1393         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1394                         See Documentation/specialix.txt.
1395
1396         spia_io_base=   [HW,MTD]
1397         spia_fio_base=
1398         spia_pedr=
1399         spia_peddr=
1400
1401         sscape=         [HW,OSS]
1402                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1403
1404         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1405                         See Documentation/scsi/st.txt.
1406
1407         st0x=           [HW,SCSI]
1408                         See header of drivers/scsi/seagate.c.
1409
1410         sti=            [PARISC,HW]
1411                         Format: <num>
1412                         Set the STI (builtin display/keyboard on the HP-PARISC
1413                         machines) console (graphic card) which should be used
1414                         as the initial boot-console.
1415                         See also comment in drivers/video/console/sticore.c.
1416
1417         sti_font=       [HW]
1418                         See comment in drivers/video/console/sticore.c.
1419
1420         stifb=          [HW]
1421                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1422
1423         stram_swap=     [HW,M68k]
1424
1425         swiotlb=        [IA-64] Number of I/O TLB slabs
1426
1427         switches=       [HW,M68k]
1428
1429         sym53c416=      [HW,SCSI]
1430                         See header of drivers/scsi/sym53c416.c.
1431
1432         t128=           [HW,SCSI]
1433                         See header of drivers/scsi/t128.c.
1434
1435         tdfx=           [HW,DRM]
1436
1437         thash_entries=  [KNL,NET]
1438                         Set number of hash buckets for TCP connection
1439
1440         time            Show timing data prefixed to each printk message line
1441
1442         tipar.timeout=  [HW,PPT]
1443                         Set communications timeout in tenths of a second
1444                         (default 15).
1445
1446         tipar.delay=    [HW,PPT]
1447                         Set inter-bit delay in microseconds (default 10).
1448
1449         tmc8xx=         [HW,SCSI]
1450                         See header of drivers/scsi/seagate.c.
1451
1452         tmscsim=        [HW,SCSI]
1453                         See comment before function dc390_setup() in
1454                         drivers/scsi/tmscsim.c.
1455
1456         tp720=          [HW,PS2]
1457
1458         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1459                         Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1460
1461         tsdev.xres=     [TS] Horizontal screen resolution.
1462         tsdev.yres=     [TS] Vertical screen resolution.
1463
1464         turbografx.map[2|3]=
1465                         [HW,JOY] TurboGraFX parallel port interface
1466                         Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1467                         See also Documentation/input/joystick-parport.txt
1468
1469         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1470                         See header of drivers/scsi/u14-34f.c.
1471
1472         uart401=        [HW,OSS]
1473                         Format: <io>,<irq>
1474
1475         uart6850=       [HW,OSS]
1476                         Format: <io>,<irq>
1477
1478         usb-handoff     [HW] Enable early USB BIOS -> OS handoff
1479
1480         usbhid.mousepoll=
1481                         [USBHID] The interval which mice are to be polled at.
1482
1483         video=          [FB] Frame buffer configuration
1484                         See Documentation/fb/modedb.txt.
1485
1486         vga=            [BOOT,IA-32] Select a particular video mode
1487                         See Documentation/i386/boot.txt and Documentation/svga.txt.
1488                         Use vga=ask for menu.
1489                         This is actually a boot loader parameter; the value is
1490                         passed to the kernel using a special protocol.
1491
1492         vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1493                         size of <nn>. This can be used to increase the
1494                         minimum size (128MB on x86). It can also be used to
1495                         decrease the size and leave more room for directly
1496                         mapped kernel RAM.
1497
1498         vmhalt=         [KNL,S390]
1499
1500         vmpoff=         [KNL,S390]
1501
1502         waveartist=     [HW,OSS]
1503                         Format: <io>,<irq>,<dma>,<dma2>
1504
1505         wd33c93=        [HW,SCSI]
1506                         See header of drivers/scsi/wd33c93.c.
1507
1508         wd7000=         [HW,SCSI]
1509                         See header of drivers/scsi/wd7000.c.
1510
1511         wdt=            [WDT] Watchdog
1512                         See Documentation/watchdog/watchdog.txt.
1513
1514         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1515         xd_geo=         See header of drivers/block/xd.c.
1516
1517         xirc2ps_cs=     [NET,PCMCIA]
1518                         Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1519
1520
1521
1522 Changelog:
1523
1524         The last known update (for 2.4.0) - the changelog was not kept before.
1525         2000-06-??      Mr. Unknown
1526
1527         Update for 2.5.49, description for most of the options introduced,
1528         references to other documentation (C files, READMEs, ..), added S390,
1529         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1530         reformatting.
1531         2002-11-24      Petr Baudis <pasky@ucw.cz>
1532                         Randy Dunlap <randy.dunlap@verizon.net>
1533
1534 TODO:
1535
1536         Add documentation for ALSA options.
1537         Add more DRM drivers.