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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 states the
21 restrictions on the kernel for the said kernel parameter to be valid. The
22 restrictions referred to are that the relevant option is valid if:
23
24         ACPI    ACPI support is enabled.
25         ALSA    ALSA sound support is enabled.
26         APIC    APIC support is enabled.
27         APM     Advanced Power Management support is enabled.
28         AX25    Appropriate AX.25 support is enabled.
29         CD      Appropriate CD support is enabled.
30         DEVFS   devfs support is enabled.
31         DRM     Direct Rendering Management support is enabled.
32         EDD     BIOS Enhanced Disk Drive Services (EDD) is enabled
33         EFI     EFI Partitioning (GPT) is enabled
34         EIDE    EIDE/ATAPI support is enabled.
35         FB      The frame buffer device is enabled.
36         HW      Appropriate hardware is enabled.
37         IA-32   IA-32 aka i386 architecture is enabled.
38         IA-64   IA-64 architecture is enabled.
39         IOSCHED More than one I/O scheduler is enabled.
40         IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
41         ISAPNP  ISA PnP code is enabled.
42         ISDN    Appropriate ISDN support is enabled.
43         JOY     Appropriate joystick support is enabled.
44         LP      Printer support is enabled.
45         LOOP    Loopback device support is enabled.
46         M68k    M68k architecture is enabled.
47                         These options have more detailed description inside of
48                         Documentation/m68k/kernel-options.txt.
49         MCA     MCA bus support is enabled.
50         MDA     MDA console support is enabled.
51         MOUSE   Appropriate mouse support is enabled.
52         MTD     MTD support is enabled.
53         NET     Appropriate network support is enabled.
54         NUMA    NUMA support is enabled.
55         NFS     Appropriate NFS support is enabled.
56         OSS     OSS sound support is enabled.
57         PARIDE  The ParIDE subsystem is enabled.
58         PARISC  The PA-RISC architecture is enabled.
59         PCI     PCI bus support is enabled.
60         PCMCIA  The PCMCIA subsystem is enabled.
61         PNP     Plug & Play support is enabled.
62         PPC     PowerPC architecture is enabled.
63         PPT     Parallel port support is enabled.
64         PS2     Appropriate PS/2 support is enabled.
65         RAM     RAM disk support is enabled.
66         S390    S390 architecture is enabled.
67         SCSI    Appropriate SCSI support is enabled.
68                         A lot of drivers has their options described inside of
69                         Documentation/scsi/.
70         SELINUX SELinux support is enabled.
71         SERIAL  Serial support is enabled.
72         SMP     The kernel is an SMP kernel.
73         SPARC   Sparc architecture is enabled.
74         SWSUSP  Software suspend 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 | noirq }
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]
127                         ACPI will balance active IRQs
128                         default in APIC mode
129
130         acpi_irq_nobalance [HW,ACPI]
131                         ACPI will not move active IRQs (default)
132                         default in PIC mode
133
134         acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
135                         use by PCI
136                         Format: <irq>,<irq>...
137
138         acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
139                         Format: <irq>,<irq>...
140
141         acpi_osi=       [HW,ACPI] empty param disables _OSI
142
143         acpi_serialize  [HW,ACPI] force serialization of AML methods
144
145         acpi_skip_timer_override [HW,ACPI]
146                         Recognize and ignore IRQ0/pin2 Interrupt Override.
147                         For broken nForce2 BIOS resulting in XT-PIC timer.
148
149         acpi_dbg_layer= [HW,ACPI]
150                         Format: <int>
151                         Each bit of the <int> indicates an ACPI debug layer,
152                         1: enable, 0: disable. It is useful for boot time
153                         debugging. After system has booted up, it can be set
154                         via /proc/acpi/debug_layer.
155
156         acpi_dbg_level= [HW,ACPI]
157                         Format: <int>
158                         Each bit of the <int> indicates an ACPI debug level,
159                         1: enable, 0: disable. It is useful for boot time
160                         debugging. After system has booted up, it can be set
161                         via /proc/acpi/debug_level.
162
163         acpi_fake_ecdt  [HW,ACPI] Workaround failure due to BIOS lacking ECDT
164
165         acpi_generic_hotkey [HW,ACPI]
166                         Allow consolidated generic hotkey driver to
167                         override platform specific driver.
168                         See also Documentation/acpi-hotkey.txt.
169
170         enable_timer_pin_1 [i386,x86-64]
171                         Enable PIN 1 of APIC timer
172                         Can be useful to work around chipset bugs
173                         (in particular on some ATI chipsets).
174                         The kernel tries to set a reasonable default.
175
176         disable_timer_pin_1 [i386,x86-64]
177                         Disable PIN 1 of APIC timer
178                         Can be useful to work around chipset bugs.
179
180         ad1816=         [HW,OSS]
181                         Format: <io>,<irq>,<dma>,<dma2>
182                         See also Documentation/sound/oss/AD1816.
183
184         ad1848=         [HW,OSS]
185                         Format: <io>,<irq>,<dma>,<dma2>,<type>
186
187         adlib=          [HW,OSS]
188                         Format: <io>
189
190         advansys=       [HW,SCSI]
191                         See header of drivers/scsi/advansys.c.
192
193         advwdt=         [HW,WDT] Advantech WDT
194                         Format: <iostart>,<iostop>
195
196         aedsp16=        [HW,OSS] Audio Excel DSP 16
197                         Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
198                         See also header of sound/oss/aedsp16.c.
199
200         aha152x=        [HW,SCSI]
201                         See Documentation/scsi/aha152x.txt.
202
203         aha1542=        [HW,SCSI]
204                         Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
205
206         aic7xxx=        [HW,SCSI]
207                         See Documentation/scsi/aic7xxx.txt.
208
209         aic79xx=        [HW,SCSI]
210                         See Documentation/scsi/aic79xx.txt.
211
212         amijoy.map=     [HW,JOY] Amiga joystick support
213                         Map of devices attached to JOY0DAT and JOY1DAT
214                         Format: <a>,<b>
215                         See also Documentation/kernel/input/joystick.txt
216
217         analog.map=     [HW,JOY] Analog joystick and gamepad support
218                         Specifies type or capabilities of an analog joystick
219                         connected to one of 16 gameports
220                         Format: <type1>,<type2>,..<type16>
221
222         apc=            [HW,SPARC]
223                         Power management functions (SPARCstation-4/5 + deriv.)
224                         Format: noidle
225                         Disable APC CPU standby support. SPARCstation-Fox does
226                         not play well with APC CPU idle - disable it if you have
227                         APC and your system crashes randomly.
228
229         apic=           [APIC,i386] Change the output verbosity whilst booting
230                         Format: { quiet (default) | verbose | debug }
231                         Change the amount of debugging information output
232                         when initialising the APIC and IO-APIC components.
233
234         apm=            [APM] Advanced Power Management
235                         See header of arch/i386/kernel/apm.c.
236
237         applicom=       [HW]
238                         Format: <mem>,<irq>
239
240         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
241                         Format: <io>,<irq>,<nodeID>
242
243         ataflop=        [HW,M68k]
244
245         atarimouse=     [HW,MOUSE] Atari Mouse
246
247         atascsi=        [HW,SCSI] Atari SCSI
248
249         atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
250                         EzKey and similar keyboards
251
252         atkbd.reset=    [HW] Reset keyboard during initialization
253
254         atkbd.set=      [HW] Select keyboard code set
255                         Format: <int> (2 = AT (default), 3 = PS/2)
256
257         atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
258                         keyboards
259
260         atkbd.softraw=  [HW] Choose between synthetic and real raw mode
261                         Format: <bool> (0 = real, 1 = synthetic (default))
262
263         atkbd.softrepeat= [HW]
264                         Use software keyboard repeat
265
266         autotest        [IA64]
267
268         awe=            [HW,OSS] AWE32/SB32/AWE64 wave table synth
269                         Format: <io>,<memsize>,<isapnp>
270
271         aztcd=          [HW,CD] Aztech CD268 CDROM driver
272                         Format: <io>,0x79 (?)
273
274         baycom_epp=     [HW,AX25]
275                         Format: <io>,<mode>
276
277         baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
278                         Format: <io>,<mode>
279                         See header of drivers/net/hamradio/baycom_par.c.
280
281         baycom_ser_fdx= [HW,AX25]
282                         BayCom Serial Port AX.25 Modem (Full Duplex Mode)
283                         Format: <io>,<irq>,<mode>[,<baud>]
284                         See header of drivers/net/hamradio/baycom_ser_fdx.c.
285
286         baycom_ser_hdx= [HW,AX25]
287                         BayCom Serial Port AX.25 Modem (Half Duplex Mode)
288                         Format: <io>,<irq>,<mode>
289                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
290
291         blkmtd_device=  [HW,MTD]
292         blkmtd_erasesz=
293         blkmtd_ro=
294         blkmtd_bs=
295         blkmtd_count=
296
297         bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
298         bttv.radio=     Most important insmod options are available as
299                         kernel args too.
300         bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
301         bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
302
303         BusLogic=       [HW,SCSI]
304                         See drivers/scsi/BusLogic.c, comment before function
305                         BusLogic_ParseDriverOptions().
306
307         c101=           [NET] Moxa C101 synchronous serial card
308
309         cachesize=      [BUGS=IA-32] Override level 2 CPU cache size detection.
310                         Sometimes CPU hardware bugs make them report the cache
311                         size incorrectly. The kernel will attempt work arounds
312                         to fix known problems, but for some CPUs it is not
313                         possible to determine what the correct size should be.
314                         This option provides an override for these situations.
315
316         cdu31a=         [HW,CD]
317                         Format: <io>,<irq>[,PAS]
318                         See header of drivers/cdrom/cdu31a.c.
319
320         chandev=        [HW,NET] Generic channel device initialisation
321
322         checkreqprot    [SELINUX] Set initial checkreqprot flag value.
323                         Format: { "0" | "1" }
324                         See security/selinux/Kconfig help text.
325                         0 -- check protection applied by kernel (includes
326                                 any implied execute protection).
327                         1 -- check protection requested by application.
328                         Default value is set via a kernel config option.
329                         Value can be changed at runtime via
330                                 /selinux/checkreqprot.
331
332         clock=          [BUGS=IA-32,HW] gettimeofday timesource override.
333                         Forces specified timesource (if avaliable) to be used
334                         when calculating gettimeofday(). If specicified
335                         timesource is not avalible, it defaults to PIT.
336                         Format: { pit | tsc | cyclone | pmtmr }
337
338         hpet=           [IA-32,HPET] option to disable HPET and use PIT.
339                         Format: disable
340
341         cm206=          [HW,CD]
342                         Format: { auto | [<io>,][<irq>] }
343
344         com20020=       [HW,NET] ARCnet - COM20020 chipset
345                         Format:
346                         <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
347
348         com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
349                         Format: <io>[,<irq>]
350
351         com90xx=        [HW,NET]
352                         ARCnet - COM90xx chipset (memory-mapped buffers)
353                         Format: <io>[,<irq>[,<memstart>]]
354
355         condev=         [HW,S390] console device
356         conmode=
357
358         console=        [KNL] Output console device and options.
359
360                 tty<n>  Use the virtual console device <n>.
361
362                 ttyS<n>[,options]
363                         Use the specified serial port.  The options are of
364                         the form "bbbbpn", where "bbbb" is the baud rate,
365                         "p" is parity ("n", "o", or "e"), and "n" is bits.
366                         Default is "9600n8".
367
368                         See also Documentation/serial-console.txt.
369
370                 uart,io,<addr>[,options]
371                 uart,mmio,<addr>[,options]
372                         Start an early, polled-mode console on the 8250/16550
373                         UART at the specified I/O port or MMIO address,
374                         switching to the matching ttyS device later.  The
375                         options are the same as for ttyS, above.
376
377         cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
378                         Format:
379                         <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
380
381         cpia_pp=        [HW,PPT]
382                         Format: { parport<nr> | auto | none }
383
384         crashkernel=nn[KMG]@ss[KMG]
385                         [KNL] Reserve a chunk of physical memory to
386                         hold a kernel to switch to with kexec on panic.
387
388         cs4232=         [HW,OSS]
389                         Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
390
391         cs89x0_dma=     [HW,NET]
392                         Format: <dma>
393
394         cs89x0_media=   [HW,NET]
395                         Format: { rj45 | aui | bnc }
396
397         cyclades=       [HW,SERIAL] Cyclades multi-serial port adapter.
398
399         dasd=           [HW,NET]
400                         See header of drivers/s390/block/dasd_devmap.c.
401
402         db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
403                         (one device per port)
404                         Format: <port#>,<type>
405                         See also Documentation/input/joystick-parport.txt
406
407         debug           [KNL] Enable kernel debugging (events log level).
408
409         decnet=         [HW,NET]
410                         Format: <area>[,<node>]
411                         See also Documentation/networking/decnet.txt.
412
413         devfs=          [DEVFS]
414                         See Documentation/filesystems/devfs/boot-options.
415
416         dhash_entries=  [KNL]
417                         Set number of hash buckets for dentry cache.
418
419         digi=           [HW,SERIAL]
420                         IO parameters + enable/disable command.
421
422         digiepca=       [HW,SERIAL]
423                         See drivers/char/README.epca and
424                         Documentation/digiepca.txt.
425
426         dmascc=         [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
427                         support available.
428                         Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
429
430         dmasound=       [HW,OSS] Sound subsystem buffers
431
432         dscc4.setup=    [NET]
433
434         dtc3181e=       [HW,SCSI]
435
436         earlyprintk=    [IA-32,X86-64]
437                         earlyprintk=vga
438                         earlyprintk=serial[,ttySn[,baudrate]]
439
440                         Append ",keep" to not disable it when the real console
441                         takes over.
442
443                         Only vga or serial at a time, not both.
444
445                         Currently only ttyS0 and ttyS1 are supported.
446
447                         Interaction with the standard serial driver is not
448                         very good.
449
450                         The VGA output is eventually overwritten by the real
451                         console.
452
453         eata=           [HW,SCSI]
454
455         eda=            [HW,PS2]
456
457         edb=            [HW,PS2]
458
459         edd=            [EDD]
460                         Format: {"of[f]" | "sk[ipmbr]"}
461                         See comment in arch/i386/boot/edd.S
462
463         eicon=          [HW,ISDN]
464                         Format: <id>,<membase>,<irq>
465
466         eisa_irq_edge=  [PARISC,HW]
467                         See header of drivers/parisc/eisa.c.
468
469         elanfreq=       [IA-32]
470                         See comment before function elanfreq_setup() in
471                         arch/i386/kernel/cpu/cpufreq/elanfreq.c.
472
473         elevator=       [IOSCHED]
474                         Format: {"as" | "cfq" | "deadline" | "noop"}
475                         See Documentation/block/as-iosched.txt and
476                         Documentation/block/deadline-iosched.txt for details.
477
478         elfcorehdr=     [IA-32]
479                         Specifies physical address of start of kernel core
480                         image elf header.
481                         See Documentation/kdump.txt for details.
482
483         enforcing       [SELINUX] Set initial enforcing status.
484                         Format: {"0" | "1"}
485                         See security/selinux/Kconfig help text.
486                         0 -- permissive (log only, no denials).
487                         1 -- enforcing (deny and log).
488                         Default value is 0.
489                         Value can be changed at runtime via /selinux/enforce.
490
491         es1370=         [HW,OSS]
492                         Format: <lineout>[,<micbias>]
493                         See also header of sound/oss/es1370.c.
494
495         es1371=         [HW,OSS]
496                         Format: <spdif>,[<nomix>,[<amplifier>]]
497                         See also header of sound/oss/es1371.c.
498
499         ether=          [HW,NET] Ethernet cards parameters
500                         This option is obsoleted by the "netdev=" option, which
501                         has equivalent usage. See its documentation for details.
502
503         eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
504                         Format: <io>[,<irq>]
505
506         fd_mcs=         [HW,SCSI]
507                         See header of drivers/scsi/fd_mcs.c.
508
509         fdomain=        [HW,SCSI]
510                         See header of drivers/scsi/fdomain.c.
511
512         floppy=         [HW]
513                         See Documentation/floppy.txt.
514
515         ftape=          [HW] Floppy Tape subsystem debugging options.
516                         See Documentation/ftape.txt.
517
518         gamecon.map[2|3]=
519                         [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
520                         support via parallel port (up to 5 devices per port)
521                         Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
522                         See also Documentation/input/joystick-parport.txt
523
524         gamma=          [HW,DRM]
525
526         gdth=           [HW,SCSI]
527                         See header of drivers/scsi/gdth.c.
528
529         gpt             [EFI] Forces disk with valid GPT signature but
530                         invalid Protective MBR to be treated as GPT.
531
532         gscd=           [HW,CD]
533                         Format: <io>
534
535         gt96100eth=     [NET] MIPS GT96100 Advanced Communication Controller
536
537         gus=            [HW,OSS]
538                         Format: <io>,<irq>,<dma>,<dma16>
539
540         gvp11=          [HW,SCSI]
541
542         hashdist=       [KNL,NUMA] Large hashes allocated during boot
543                         are distributed across NUMA nodes.  Defaults on
544                         for IA-64, off otherwise.
545                         Format: 0 | 1 (for off | on)
546
547         hcl=            [IA-64] SGI's Hardware Graph compatibility layer
548
549         hd=             [EIDE] (E)IDE hard drive subsystem geometry
550                         Format: <cyl>,<head>,<sect>
551
552         hd?=            [HW] (E)IDE subsystem
553         hd?lun=         See Documentation/ide.txt.
554
555         highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
556                         size of <nn>. This works even on boxes that have no
557                         highmem otherwise. This also works to reduce highmem
558                         size on bigger boxes.
559
560         hisax=          [HW,ISDN]
561                         See Documentation/isdn/README.HiSax.
562
563         hugepages=      [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
564
565         noirqbalance    [IA-32,SMP,KNL] Disable kernel irq balancing
566
567         i8042.direct    [HW] Put keyboard port into non-translated mode
568         i8042.dumbkbd   [HW] Pretend that controlled can only read data from
569                              keyboard and can not control its state
570                              (Don't attempt to blink the leds)
571         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
572         i8042.nokbd     [HW] Don't check/create keyboard port
573         i8042.nomux     [HW] Don't check presence of an active multiplexing
574                              controller
575         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
576                              controllers
577         i8042.panicblink=
578                         [HW] Frequency with which keyboard LEDs should blink
579                              when kernel panics (default is 0.5 sec)
580         i8042.reset     [HW] Reset the controller during init and cleanup
581         i8042.unlock    [HW] Unlock (ignore) the keylock
582
583         i810=           [HW,DRM]
584
585         i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
586                         indicates that the driver is running on unsupported
587                         hardware.
588         i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
589                         does not match list of supported models.
590         i8k.power_status
591                         [HW] Report power status in /proc/i8k
592                         (disabled by default)
593         i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
594                         capability is set.
595
596         ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
597                         See Documentation/mca.txt.
598
599         icn=            [HW,ISDN]
600                         Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
601
602         ide=            [HW] (E)IDE subsystem
603                         Format: ide=nodma or ide=doubler or ide=reverse
604                         See Documentation/ide.txt.
605
606         ide?=           [HW] (E)IDE subsystem
607                         Format: ide?=noprobe or chipset specific parameters.
608                         See Documentation/ide.txt.
609
610         idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
611                         See Documentation/ide.txt.
612
613         idle=           [HW]
614                         Format: idle=poll or idle=halt
615
616         ihash_entries=  [KNL]
617                         Set number of hash buckets for inode cache.
618
619         in2000=         [HW,SCSI]
620                         See header of drivers/scsi/in2000.c.
621
622         init=           [KNL]
623                         Format: <full_path>
624                         Run specified binary instead of /sbin/init as init
625                         process.
626
627         initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
628                         for working out where the kernel is dying during
629                         startup.
630
631         initrd=         [BOOT] Specify the location of the initial ramdisk
632
633         inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
634                         Format: <irq>
635
636         combined_mode=  [HW] control which driver uses IDE ports in combined
637                         mode: legacy IDE driver, libata, or both
638                         (in the libata case, libata.atapi_enabled=1 may be
639                         useful as well).  Note that using the ide or libata
640                         options may affect your device naming (e.g. by
641                         changing hdc to sdb).
642                         Format: combined (default), ide, or libata
643
644         inttest=        [IA64]
645
646         io7=            [HW] IO7 for Marvel based alpha systems
647                         See comment before marvel_specify_io7 in
648                         arch/alpha/kernel/core_marvel.c.
649
650         ip=             [IP_PNP]
651                         See Documentation/nfsroot.txt.
652
653         ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
654                         See comment before ip2_setup() in drivers/char/ip2.c.
655
656         ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
657                         See header of drivers/scsi/ips.c.
658
659         irqfixup        [HW]
660                         When an interrupt is not handled search all handlers
661                         for it. Intended to get systems with badly broken
662                         firmware running.
663
664         irqpoll         [HW]
665                         When an interrupt is not handled search all handlers
666                         for it. Also check all handlers each timer
667                         interrupt. Intended to get systems with badly broken
668                         firmware running.
669
670         isapnp=         [ISAPNP]
671                         Format: <RDP>,<reset>,<pci_scan>,<verbosity>
672
673         isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
674                         Format: <cpu number>,...,<cpu number>
675                         This option can be used to specify one or more CPUs
676                         to isolate from the general SMP balancing and scheduling
677                         algorithms. The only way to move a process onto or off
678                         an "isolated" CPU is via the CPU affinity syscalls.
679                         <cpu number> begins at 0 and the maximum value is
680                         "number of CPUs in system - 1".
681
682                         This option is the preferred way to isolate CPUs. The
683                         alternative -- manually setting the CPU mask of all
684                         tasks in the system -- can cause problems and
685                         suboptimal load balancer performance.
686
687         isp16=          [HW,CD]
688                         Format: <io>,<irq>,<dma>,<setup>
689
690         iucv=           [HW,NET]
691
692         js=             [HW,JOY] Analog joystick
693                         See Documentation/input/joystick.txt.
694
695         keepinitrd      [HW,ARM]
696
697         kstack=N        [IA-32,X86-64] Print N words from the kernel stack
698                         in oops dumps.
699
700         l2cr=           [PPC]
701
702         lapic           [IA-32,APIC] Enable the local APIC even if BIOS
703                         disabled it.
704
705         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
706                         Format: addr:<io>,irq:<irq>
707
708         llsc*=          [IA64] See function print_params() in
709                         arch/ia64/sn/kernel/llsc4.c.
710
711         load_ramdisk=   [RAM] List of ramdisks to load from floppy
712                         See Documentation/ramdisk.txt.
713
714         lockd.udpport=  [NFS]
715
716         lockd.tcpport=  [NFS]
717
718         logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
719                         Format: <irq>
720
721         loglevel=       All Kernel Messages with a loglevel smaller than the
722                         console loglevel will be printed to the console. It can
723                         also be changed with klogd or other programs. The
724                         loglevels are defined as follows:
725
726                         0 (KERN_EMERG)          system is unusable
727                         1 (KERN_ALERT)          action must be taken immediately
728                         2 (KERN_CRIT)           critical conditions
729                         3 (KERN_ERR)            error conditions
730                         4 (KERN_WARNING)        warning conditions
731                         5 (KERN_NOTICE)         normal but significant condition
732                         6 (KERN_INFO)           informational
733                         7 (KERN_DEBUG)          debug-level messages
734
735         log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
736                         Format: { n | nk | nM }
737                         n must be a power of two.  The default size
738                         is set in the kernel config file.
739
740         lp=0            [LP]    Specify parallel ports to use, e.g,
741         lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
742         lp=reset                first parallel port). 'lp=0' disables the
743         lp=auto                 printer driver. 'lp=reset' (which can be
744                                 specified in addition to the ports) causes
745                                 attached printers to be reset. Using
746                                 lp=port1,port2,... specifies the parallel ports
747                                 to associate lp devices with, starting with
748                                 lp0. A port specification may be 'none' to skip
749                                 that lp device, or a parport name such as
750                                 'parport0'. Specifying 'lp=auto' instead of a
751                                 port specification list means that device IDs
752                                 from each port should be examined, to see if
753                                 an IEEE 1284-compliant printer is attached; if
754                                 so, the driver will manage that printer.
755                                 See also header of drivers/char/lp.c.
756
757         lpj=n           [KNL]
758                         Sets loops_per_jiffy to given constant, thus avoiding
759                         time-consuming boot-time autodetection (up to 250 ms per
760                         CPU). 0 enables autodetection (default). To determine
761                         the correct value for your kernel, boot with normal
762                         autodetection and see what value is printed. Note that
763                         on SMP systems the preset will be applied to all CPUs,
764                         which is likely to cause problems if your CPUs need
765                         significantly divergent settings. An incorrect value
766                         will cause delays in the kernel to be wrong, leading to
767                         unpredictable I/O errors and other breakage. Although
768                         unlikely, in the extreme case this might damage your
769                         hardware.
770
771         ltpc=           [NET]
772                         Format: <io>,<irq>,<dma>
773
774         mac5380=        [HW,SCSI] Format:
775                         <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
776
777         mac53c9x=       [HW,SCSI] Format:
778                         <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
779
780         machvec=        [IA64] Force the use of a particular machine-vector
781                         (machvec) in a generic kernel.
782                         Example: machvec=hpzx1_swiotlb
783
784         mad16=          [HW,OSS] Format:
785                         <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
786
787         maui=           [HW,OSS]
788                         Format: <io>,<irq>
789
790         max_loop=       [LOOP] Maximum number of loopback devices that can
791                         be mounted
792                         Format: <1-256>
793
794         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
795                         should make use of
796
797         max_addr=[KMG]  [KNL,BOOT,ia64] All physical memory greater than or
798                         equal to this physical address is ignored.
799
800         max_luns=       [SCSI] Maximum number of LUNs to probe.
801                         Should be between 1 and 2^32-1.
802
803         max_report_luns=
804                         [SCSI] Maximum number of LUNs received.
805                         Should be between 1 and 16384.
806
807         mca-pentium     [BUGS=IA-32]
808
809         mcatest=        [IA-64]
810
811         mcd=            [HW,CD]
812                         Format: <port>,<irq>,<mitsumi_bug_93_wait>
813
814         mcdx=           [HW,CD]
815
816         mce             [IA-32] Machine Check Exception
817
818         md=             [HW] RAID subsystems devices and level
819                         See Documentation/md.txt.
820
821         mdacon=         [MDA]
822                         Format: <first>,<last>
823                         Specifies range of consoles to be captured by the MDA.
824
825         mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
826                         Amount of memory to be used when the kernel is not able
827                         to see the whole system memory or for test.
828                         [IA-32] Use together with memmap= to avoid physical
829                         address space collisions. Without memmap= PCI devices
830                         could be placed at addresses belonging to unused RAM.
831
832         mem=nopentium   [BUGS=IA-32] Disable usage of 4MB pages for kernel
833                         memory.
834
835         memmap=exactmap [KNL,IA-32] Enable setting of an exact
836                         E820 memory map, as specified by the user.
837                         Such memmap=exactmap lines can be constructed based on
838                         BIOS output or other requirements. See the memmap=nn@ss
839                         option description.
840
841         memmap=nn[KMG]@ss[KMG]
842                         [KNL] Force usage of a specific region of memory
843                         Region of memory to be used, from ss to ss+nn.
844
845         memmap=nn[KMG]#ss[KMG]
846                         [KNL,ACPI] Mark specific memory as ACPI data.
847                         Region of memory to be used, from ss to ss+nn.
848
849         memmap=nn[KMG]$ss[KMG]
850                         [KNL,ACPI] Mark specific memory as reserved.
851                         Region of memory to be used, from ss to ss+nn.
852
853         meye.*=         [HW] Set MotionEye Camera parameters
854                         See Documentation/video4linux/meye.txt.
855
856         mga=            [HW,DRM]
857
858         mousedev.tap_time=
859                         [MOUSE] Maximum time between finger touching and
860                         leaving touchpad surface for touch to be considered
861                         a tap and be reported as a left button click (for
862                         touchpads working in absolute mode only).
863                         Format: <msecs>
864         mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
865                         reporting absolute coordinates, such as tablets
866         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
867                         reporting absolute coordinates, such as tablets
868
869         mpu401=         [HW,OSS]
870                         Format: <io>,<irq>
871
872         MTD_Partition=  [MTD]
873                         Format: <name>,<region-number>,<size>,<offset>
874
875         MTD_Region=     [MTD] Format:
876                         <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
877
878         mtdparts=       [MTD]
879                         See drivers/mtd/cmdline.c.
880
881         mtouchusb.raw_coordinates=
882                         [HW] Make the MicroTouch USB driver use raw coordinates
883                         ('y', default) or cooked coordinates ('n')
884
885         n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
886
887         NCR_D700=       [HW,SCSI]
888                         See header of drivers/scsi/NCR_D700.c.
889
890         ncr5380=        [HW,SCSI]
891
892         ncr53c400=      [HW,SCSI]
893
894         ncr53c400a=     [HW,SCSI]
895
896         ncr53c406a=     [HW,SCSI]
897
898         ncr53c8xx=      [HW,SCSI]
899
900         netdev=         [NET] Network devices parameters
901                         Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
902                         Note that mem_start is often overloaded to mean
903                         something different and driver-specific.
904                         This usage is only documented in each driver source
905                         file if at all.
906
907         nfsaddrs=       [NFS]
908                         See Documentation/nfsroot.txt.
909
910         nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
911                         See Documentation/nfsroot.txt.
912
913         nfs.callback_tcpport=
914                         [NFS] set the TCP port on which the NFSv4 callback
915                         channel should listen.
916
917         nfs.idmap_cache_timeout=
918                         [NFS] set the maximum lifetime for idmapper cache
919                         entries.
920
921         nmi_watchdog=   [KNL,BUGS=IA-32] Debugging features for SMP kernels
922
923         no387           [BUGS=IA-32] Tells the kernel to use the 387 maths
924                         emulation library even if a 387 maths coprocessor
925                         is present.
926
927         noalign         [KNL,ARM]
928
929         noapic          [SMP,APIC] Tells the kernel to not make use of any
930                         IOAPICs that may be present in the system.
931
932         noasync         [HW,M68K] Disables async and sync negotiation for
933                         all devices.
934
935         nobats          [PPC] Do not use BATs for mapping kernel lowmem
936                         on "Classic" PPC cores.
937
938         nocache         [ARM]
939
940         nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
941
942         noexec          [IA-64]
943
944         noexec          [IA-32,X86-64]
945                         noexec=on: enable non-executable mappings (default)
946                         noexec=off: disable nn-executable mappings
947
948         nofxsr          [BUGS=IA-32]
949
950         nohlt           [BUGS=ARM]
951
952         no-hlt          [BUGS=IA-32] Tells the kernel that the hlt
953                         instruction doesn't work correctly and not to
954                         use it.
955
956         nohalt          [IA-64] Tells the kernel not to use the power saving
957                         function PAL_HALT_LIGHT when idle. This increases
958                         power-consumption. On the positive side, it reduces
959                         interrupt wake-up latency, which may improve performance
960                         in certain environments such as networked servers or
961                         real-time systems.
962
963         noirqdebug      [IA-32] Disables the code which attempts to detect and
964                         disable unhandled interrupt sources.
965
966         noisapnp        [ISAPNP] Disables ISA PnP code.
967
968         noinitrd        [RAM] Tells the kernel not to load any configured
969                         initial RAM disk.
970
971         nointroute      [IA-64]
972
973         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
974
975         noltlbs         [PPC] Do not use large page/tlb entries for kernel
976                         lowmem mapping on PPC40x.
977
978         nomce           [IA-32] Machine Check Exception
979
980         noresidual      [PPC] Don't use residual data on PReP machines.
981
982         noresume        [SWSUSP] Disables resume and restores original swap
983                         space.
984
985         no-scroll       [VGA] Disables scrollback.
986                         This is required for the Braillex ib80-piezo Braille
987                         reader made by F.H. Papenmeier (Germany).
988
989         nosbagart       [IA-64]
990
991         nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
992
993         nosync          [HW,M68K] Disables sync negotiation for all devices.
994
995         notsc           [BUGS=IA-32] Disable Time Stamp Counter
996
997         nousb           [USB] Disable the USB subsystem
998
999         nowb            [ARM]
1000
1001         opl3=           [HW,OSS]
1002                         Format: <io>
1003
1004         opl3sa=         [HW,OSS]
1005                         Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1006
1007         opl3sa2=        [HW,OSS] Format:
1008                         <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1009
1010         oprofile.timer= [HW]
1011                         Use timer interrupt instead of performance counters
1012
1013         optcd=          [HW,CD]
1014                         Format: <io>
1015
1016         osst=           [HW,SCSI] SCSI Tape Driver
1017                         Format: <buffer_size>,<write_threshold>
1018                         See also Documentation/scsi/st.txt.
1019
1020         panic=          [KNL] Kernel behaviour on panic
1021                         Format: <timeout>
1022
1023         parkbd.port=    [HW] Parallel port number the keyboard adapter is
1024                         connected to, default is 0.
1025                         Format: <parport#>
1026         parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
1027                         0 for XT, 1 for AT (default is AT).
1028                         Format: <mode>
1029
1030         parport=        [HW,PPT] Specify parallel ports. 0 disables.
1031                         Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1032                         Use 'auto' to force the driver to use any
1033                         IRQ/DMA settings detected (the default is to
1034                         ignore detected IRQ/DMA settings because of
1035                         possible conflicts). You can specify the base
1036                         address, IRQ, and DMA settings; IRQ and DMA
1037                         should be numbers, or 'auto' (for using detected
1038                         settings on that particular port), or 'nofifo'
1039                         (to avoid using a FIFO even if it is detected).
1040                         Parallel ports are assigned in the order they
1041                         are specified on the command line, starting
1042                         with parport0.
1043
1044         parport_init_mode=      [HW,PPT]
1045                         Configure VIA parallel port to operate in
1046                         a specific mode. This is necessary on Pegasos
1047                         computer where firmware has no options for setting
1048                         up parallel port mode and sets it to spp.
1049                         Currently this function knows 686a and 8231 chips.
1050                         Format: [spp|ps2|epp|ecp|ecpepp]
1051
1052         pas2=           [HW,OSS] Format:
1053                         <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1054
1055         pas16=          [HW,SCSI]
1056                         See header of drivers/scsi/pas16.c.
1057
1058         pcbit=          [HW,ISDN]
1059
1060         pcd.            [PARIDE]
1061                         See header of drivers/block/paride/pcd.c.
1062                         See also Documentation/paride.txt.
1063
1064         pci=option[,option...]  [PCI] various PCI subsystem options:
1065                 off             [IA-32] don't probe for the PCI bus
1066                 bios            [IA-32] force use of PCI BIOS, don't access
1067                                 the hardware directly. Use this if your machine
1068                                 has a non-standard PCI host bridge.
1069                 nobios          [IA-32] disallow use of PCI BIOS, only direct
1070                                 hardware access methods are allowed. Use this
1071                                 if you experience crashes upon bootup and you
1072                                 suspect they are caused by the BIOS.
1073                 conf1           [IA-32] Force use of PCI Configuration
1074                                 Mechanism 1.
1075                 conf2           [IA-32] Force use of PCI Configuration
1076                                 Mechanism 2.
1077                 nosort          [IA-32] Don't sort PCI devices according to
1078                                 order given by the PCI BIOS. This sorting is
1079                                 done to get a device order compatible with
1080                                 older kernels.
1081                 biosirq         [IA-32] Use PCI BIOS calls to get the interrupt
1082                                 routing table. These calls are known to be buggy
1083                                 on several machines and they hang the machine
1084                                 when used, but on other computers it's the only
1085                                 way to get the interrupt routing table. Try
1086                                 this option if the kernel is unable to allocate
1087                                 IRQs or discover secondary PCI buses on your
1088                                 motherboard.
1089                 rom             [IA-32] Assign address space to expansion ROMs.
1090                                 Use with caution as certain devices share
1091                                 address decoders between ROMs and other
1092                                 resources.
1093                 irqmask=0xMMMM  [IA-32] Set a bit mask of IRQs allowed to be
1094                                 assigned automatically to PCI devices. You can
1095                                 make the kernel exclude IRQs of your ISA cards
1096                                 this way.
1097                 pirqaddr=0xAAAAA        [IA-32] Specify the physical address
1098                                 of the PIRQ table (normally generated
1099                                 by the BIOS) if it is outside the
1100                                 F0000h-100000h range.
1101                 lastbus=N       [IA-32] Scan all buses thru bus #N. Can be
1102                                 useful if the kernel is unable to find your
1103                                 secondary buses and you want to tell it
1104                                 explicitly which ones they are.
1105                 assign-busses   [IA-32] Always assign all PCI bus
1106                                 numbers ourselves, overriding
1107                                 whatever the firmware may have done.
1108                 usepirqmask     [IA-32] Honor the possible IRQ mask stored
1109                                 in the BIOS $PIR table. This is needed on
1110                                 some systems with broken BIOSes, notably
1111                                 some HP Pavilion N5400 and Omnibook XE3
1112                                 notebooks. This will have no effect if ACPI
1113                                 IRQ routing is enabled.
1114                 noacpi          [IA-32] Do not use ACPI for IRQ routing
1115                                 or for PCI scanning.
1116                 routeirq        Do IRQ routing for all PCI devices.
1117                                 This is normally done in pci_enable_device(),
1118                                 so this option is a temporary workaround
1119                                 for broken drivers that don't call it.
1120                 firmware        [ARM] Do not re-enumerate the bus but instead
1121                                 just use the configuration from the
1122                                 bootloader. This is currently used on
1123                                 IXP2000 systems where the bus has to be
1124                                 configured a certain way for adjunct CPUs.
1125
1126         pcmv=           [HW,PCMCIA] BadgePAD 4
1127
1128         pd.             [PARIDE]
1129                         See Documentation/paride.txt.
1130
1131         pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1132                         boot time.
1133                         Format: { 0 | 1 }
1134                         See arch/parisc/kernel/pdc_chassis.c
1135
1136         pf.             [PARIDE]
1137                         See Documentation/paride.txt.
1138
1139         pg.             [PARIDE]
1140                         See Documentation/paride.txt.
1141
1142         pirq=           [SMP,APIC] Manual mp-table setup
1143                         See Documentation/i386/IO-APIC.txt.
1144
1145         plip=           [PPT,NET] Parallel port network link
1146                         Format: { parport<nr> | timid | 0 }
1147                         See also Documentation/parport.txt.
1148
1149         pnpacpi=        [ACPI]
1150                         { off }
1151
1152         pnpbios=        [ISAPNP]
1153                         { on | off | curr | res | no-curr | no-res }
1154
1155         pnp_reserve_irq=
1156                         [ISAPNP] Exclude IRQs for the autoconfiguration
1157
1158         pnp_reserve_dma=
1159                         [ISAPNP] Exclude DMAs for the autoconfiguration
1160
1161         pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1162                         Ranges are in pairs (I/O port base and size).
1163
1164         pnp_reserve_mem=
1165                         [ISAPNP] Exclude memory regions for the
1166                         autoconfiguration.
1167                         Ranges are in pairs (memory base and size).
1168
1169         profile=        [KNL] Enable kernel profiling via /proc/profile
1170                         Format: [schedule,]<number>
1171                         Param: "schedule" - profile schedule points.
1172                         Param: <number> - step/bucket size as a power of 2 for
1173                                 statistical time based profiling.
1174
1175         processor.max_cstate=   [HW,ACPI]
1176                         Limit processor to maximum C-state
1177                         max_cstate=9 overrides any DMI blacklist limit.
1178
1179         processor.nocst [HW,ACPI]
1180                         Ignore the _CST method to determine C-states,
1181                         instead using the legacy FADT method
1182
1183         prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1184                         before loading.
1185                         See Documentation/ramdisk.txt.
1186
1187         psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
1188                         probe for; one of (bare|imps|exps|lifebook|any).
1189         psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
1190                         per second.
1191         psmouse.resetafter=     [HW,MOUSE]
1192                         Try to reset the device after so many bad packets
1193                         (0 = never).
1194         psmouse.resolution=
1195                         [HW,MOUSE] Set desired mouse resolution, in dpi.
1196         psmouse.smartscroll=
1197                         [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1198                         0 = disabled, 1 = enabled (default).
1199
1200         pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
1201                         Format:
1202                         <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1203
1204         pt.             [PARIDE]
1205                         See Documentation/paride.txt.
1206
1207         quiet=          [KNL] Disable log messages
1208
1209         r128=           [HW,DRM]
1210
1211         raid=           [HW,RAID]
1212                         See Documentation/md.txt.
1213
1214         ramdisk=        [RAM] Sizes of RAM disks in kilobytes [deprecated]
1215                         See Documentation/ramdisk.txt.
1216
1217         ramdisk_blocksize=      [RAM]
1218                         See Documentation/ramdisk.txt.
1219
1220         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
1221                         New name for the ramdisk parameter.
1222                         See Documentation/ramdisk.txt.
1223
1224         rdinit=         [KNL]
1225                         Format: <full_path>
1226                         Run specified binary instead of /init from the ramdisk,
1227                         used for early userspace startup. See initrd.
1228
1229         reboot=         [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1230                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
1231                         See arch/*/kernel/reboot.c.
1232
1233         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
1234
1235         resume=         [SWSUSP]
1236                         Specify the partition device for software suspend
1237
1238         rhash_entries=  [KNL,NET]
1239                         Set number of hash buckets for route cache
1240
1241         riscom8=        [HW,SERIAL]
1242                         Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1243
1244         ro              [KNL] Mount root device read-only on boot
1245
1246         root=           [KNL] Root filesystem
1247
1248         rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
1249                         mount the root filesystem
1250
1251         rootflags=      [KNL] Set root filesystem mount option string
1252
1253         rootfstype=     [KNL] Set root filesystem type
1254
1255         rw              [KNL] Mount root device read-write on boot
1256
1257         S               [KNL] Run init in single mode
1258
1259         sa1100ir        [NET]
1260                         See drivers/net/irda/sa1100_ir.c.
1261
1262         sb=             [HW,OSS]
1263                         Format: <io>,<irq>,<dma>,<dma2>
1264
1265         sbni=           [NET] Granch SBNI12 leased line adapter
1266
1267         sbpcd=          [HW,CD] Soundblaster CD adapter
1268                         Format: <io>,<type>
1269                         See a comment before function sbpcd_setup() in
1270                         drivers/cdrom/sbpcd.c.
1271
1272         sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
1273                         Format: <io>[,<timeout>[,<isapnp>]]
1274
1275         scsi_debug_*=   [SCSI]
1276                         See drivers/scsi/scsi_debug.c.
1277
1278         scsi_default_dev_flags=
1279                         [SCSI] SCSI default device flags
1280                         Format: <integer>
1281
1282         scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1283                         Format: <vendor>:<model>:<flags>
1284                         (flags are integer value)
1285
1286         scsi_logging=   [SCSI]
1287
1288         selinux         [SELINUX] Disable or enable SELinux at boot time.
1289                         Format: { "0" | "1" }
1290                         See security/selinux/Kconfig help text.
1291                         0 -- disable.
1292                         1 -- enable.
1293                         Default value is set via kernel config option.
1294                         If enabled at boot time, /selinux/disable can be used
1295                         later to disable prior to initial policy load.
1296
1297         serialnumber    [BUGS=IA-32]
1298
1299         sg_def_reserved_size=   [SCSI]
1300
1301         sgalaxy=        [HW,OSS]
1302                         Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1303
1304         shapers=        [NET]
1305                         Maximal number of shapers.
1306
1307         sim710=         [SCSI,HW]
1308                         See header of drivers/scsi/sim710.c.
1309
1310         simeth=         [IA-64]
1311         simscsi=
1312
1313         sjcd=           [HW,CD]
1314                         Format: <io>,<irq>,<dma>
1315                         See header of drivers/cdrom/sjcd.c.
1316
1317         slram=          [HW,MTD]
1318
1319         smart2=         [HW]
1320                         Format: <io1>[,<io2>[,...,<io8>]]
1321
1322         snd-ad1816a=    [HW,ALSA]
1323
1324         snd-ad1848=     [HW,ALSA]
1325
1326         snd-ali5451=    [HW,ALSA]
1327
1328         snd-als100=     [HW,ALSA]
1329
1330         snd-als4000=    [HW,ALSA]
1331
1332         snd-azt2320=    [HW,ALSA]
1333
1334         snd-cmi8330=    [HW,ALSA]
1335
1336         snd-cmipci=     [HW,ALSA]
1337
1338         snd-cs4231=     [HW,ALSA]
1339
1340         snd-cs4232=     [HW,ALSA]
1341
1342         snd-cs4236=     [HW,ALSA]
1343
1344         snd-cs4281=     [HW,ALSA]
1345
1346         snd-cs46xx=     [HW,ALSA]
1347
1348         snd-dt019x=     [HW,ALSA]
1349
1350         snd-dummy=      [HW,ALSA]
1351
1352         snd-emu10k1=    [HW,ALSA]
1353
1354         snd-ens1370=    [HW,ALSA]
1355
1356         snd-ens1371=    [HW,ALSA]
1357
1358         snd-es968=      [HW,ALSA]
1359
1360         snd-es1688=     [HW,ALSA]
1361
1362         snd-es18xx=     [HW,ALSA]
1363
1364         snd-es1938=     [HW,ALSA]
1365
1366         snd-es1968=     [HW,ALSA]
1367
1368         snd-fm801=      [HW,ALSA]
1369
1370         snd-gusclassic= [HW,ALSA]
1371
1372         snd-gusextreme= [HW,ALSA]
1373
1374         snd-gusmax=     [HW,ALSA]
1375
1376         snd-hdsp=       [HW,ALSA]
1377
1378         snd-ice1712=    [HW,ALSA]
1379
1380         snd-intel8x0=   [HW,ALSA]
1381
1382         snd-interwave=  [HW,ALSA]
1383
1384         snd-interwave-stb=
1385                         [HW,ALSA]
1386
1387         snd-korg1212=   [HW,ALSA]
1388
1389         snd-maestro3=   [HW,ALSA]
1390
1391         snd-mpu401=     [HW,ALSA]
1392
1393         snd-mtpav=      [HW,ALSA]
1394
1395         snd-nm256=      [HW,ALSA]
1396
1397         snd-opl3sa2=    [HW,ALSA]
1398
1399         snd-opti92x-ad1848=
1400                         [HW,ALSA]
1401
1402         snd-opti92x-cs4231=
1403                         [HW,ALSA]
1404
1405         snd-opti93x=    [HW,ALSA]
1406
1407         snd-pmac=       [HW,ALSA]
1408
1409         snd-rme32=      [HW,ALSA]
1410
1411         snd-rme96=      [HW,ALSA]
1412
1413         snd-rme9652=    [HW,ALSA]
1414
1415         snd-sb8=        [HW,ALSA]
1416
1417         snd-sb16=       [HW,ALSA]
1418
1419         snd-sbawe=      [HW,ALSA]
1420
1421         snd-serial=     [HW,ALSA]
1422
1423         snd-sgalaxy=    [HW,ALSA]
1424
1425         snd-sonicvibes= [HW,ALSA]
1426
1427         snd-sun-amd7930=
1428                         [HW,ALSA]
1429
1430         snd-sun-cs4231= [HW,ALSA]
1431
1432         snd-trident=    [HW,ALSA]
1433
1434         snd-usb-audio=  [HW,ALSA,USB]
1435
1436         snd-via82xx=    [HW,ALSA]
1437
1438         snd-virmidi=    [HW,ALSA]
1439
1440         snd-wavefront=  [HW,ALSA]
1441
1442         snd-ymfpci=     [HW,ALSA]
1443
1444         sonicvibes=     [HW,OSS]
1445                         Format: <reverb>
1446
1447         sonycd535=      [HW,CD]
1448                         Format: <io>[,<irq>]
1449
1450         sonypi.*=       [HW] Sony Programmable I/O Control Device driver
1451                         See Documentation/sonypi.txt
1452
1453         specialix=      [HW,SERIAL] Specialix multi-serial port adapter
1454                         See Documentation/specialix.txt.
1455
1456         spia_io_base=   [HW,MTD]
1457         spia_fio_base=
1458         spia_pedr=
1459         spia_peddr=
1460
1461         sscape=         [HW,OSS]
1462                         Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1463
1464         st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
1465                         See Documentation/scsi/st.txt.
1466
1467         st0x=           [HW,SCSI]
1468                         See header of drivers/scsi/seagate.c.
1469
1470         sti=            [PARISC,HW]
1471                         Format: <num>
1472                         Set the STI (builtin display/keyboard on the HP-PARISC
1473                         machines) console (graphic card) which should be used
1474                         as the initial boot-console.
1475                         See also comment in drivers/video/console/sticore.c.
1476
1477         sti_font=       [HW]
1478                         See comment in drivers/video/console/sticore.c.
1479
1480         stifb=          [HW]
1481                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1482
1483         swiotlb=        [IA-64] Number of I/O TLB slabs
1484
1485         switches=       [HW,M68k]
1486
1487         sym53c416=      [HW,SCSI]
1488                         See header of drivers/scsi/sym53c416.c.
1489
1490         t128=           [HW,SCSI]
1491                         See header of drivers/scsi/t128.c.
1492
1493         tdfx=           [HW,DRM]
1494
1495         thash_entries=  [KNL,NET]
1496                         Set number of hash buckets for TCP connection
1497
1498         time            Show timing data prefixed to each printk message line
1499
1500         tipar.timeout=  [HW,PPT]
1501                         Set communications timeout in tenths of a second
1502                         (default 15).
1503
1504         tipar.delay=    [HW,PPT]
1505                         Set inter-bit delay in microseconds (default 10).
1506
1507         tmc8xx=         [HW,SCSI]
1508                         See header of drivers/scsi/seagate.c.
1509
1510         tmscsim=        [HW,SCSI]
1511                         See comment before function dc390_setup() in
1512                         drivers/scsi/tmscsim.c.
1513
1514         tp720=          [HW,PS2]
1515
1516         trix=           [HW,OSS] MediaTrix AudioTrix Pro
1517                         Format:
1518                         <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1519
1520         tsdev.xres=     [TS] Horizontal screen resolution.
1521         tsdev.yres=     [TS] Vertical screen resolution.
1522
1523         turbografx.map[2|3]=    [HW,JOY]
1524                         TurboGraFX parallel port interface
1525                         Format:
1526                         <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1527                         See also Documentation/input/joystick-parport.txt
1528
1529         u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1530                         See header of drivers/scsi/u14-34f.c.
1531
1532         uart401=        [HW,OSS]
1533                         Format: <io>,<irq>
1534
1535         uart6850=       [HW,OSS]
1536                         Format: <io>,<irq>
1537
1538         usbhid.mousepoll=
1539                         [USBHID] The interval which mice are to be polled at.
1540
1541         video=          [FB] Frame buffer configuration
1542                         See Documentation/fb/modedb.txt.
1543
1544         vga=            [BOOT,IA-32] Select a particular video mode
1545                         See Documentation/i386/boot.txt and
1546                         Documentation/svga.txt.
1547                         Use vga=ask for menu.
1548                         This is actually a boot loader parameter; the value is
1549                         passed to the kernel using a special protocol.
1550
1551         vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1552                         size of <nn>. This can be used to increase the
1553                         minimum size (128MB on x86). It can also be used to
1554                         decrease the size and leave more room for directly
1555                         mapped kernel RAM.
1556
1557         vmhalt=         [KNL,S390]
1558
1559         vmpoff=         [KNL,S390]
1560
1561         waveartist=     [HW,OSS]
1562                         Format: <io>,<irq>,<dma>,<dma2>
1563
1564         wd33c93=        [HW,SCSI]
1565                         See header of drivers/scsi/wd33c93.c.
1566
1567         wd7000=         [HW,SCSI]
1568                         See header of drivers/scsi/wd7000.c.
1569
1570         wdt=            [WDT] Watchdog
1571                         See Documentation/watchdog/watchdog.txt.
1572
1573         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1574         xd_geo=         See header of drivers/block/xd.c.
1575
1576         xirc2ps_cs=     [NET,PCMCIA]
1577                         Format:
1578                         <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1579
1580
1581 ______________________________________________________________________
1582 Changelog:
1583
1584 2000-06-??      Mr. Unknown
1585         The last known update (for 2.4.0) - the changelog was not kept before.
1586
1587 2002-11-24      Petr Baudis <pasky@ucw.cz>
1588                 Randy Dunlap <randy.dunlap@verizon.net>
1589         Update for 2.5.49, description for most of the options introduced,
1590         references to other documentation (C files, READMEs, ..), added S390,
1591         PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1592         reformatting.
1593
1594 2005-10-19      Randy Dunlap <rdunlap@xenotime.net>
1595         Lots of typos, whitespace, some reformatting.
1596
1597 TODO:
1598
1599         Add documentation for ALSA options.
1600         Add more DRM drivers.