]> bbs.cooldavid.org Git - net-next-2.6.git/blame - Documentation/kernel-parameters.txt
[PATCH] kdump: introduce "reset_devices" command line option
[net-next-2.6.git] / Documentation / kernel-parameters.txt
CommitLineData
0ee9d71f 1 Kernel Parameters
1da177e4
LT
2 ~~~~~~~~~~~~~~~~~
3
4The 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
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are 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
a901ebb9
SR
20This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
6585fa8a
SR
27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
1da177e4
LT
31
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
a9913044 38 DRM Direct Rendering Management support is enabled.
1da177e4
LT
39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
1da177e4
LT
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
309e57df 59 MSI Message Signaled Interrupts (PCI).
1da177e4
LT
60 MTD MTD support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
734efb46 63 GENERIC_TIME The generic timeofday code is enabled.
1da177e4
LT
64 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PARIDE The ParIDE subsystem is enabled.
67 PARISC The PA-RISC architecture is enabled.
68 PCI PCI bus support is enabled.
69 PCMCIA The PCMCIA subsystem is enabled.
70 PNP Plug & Play support is enabled.
71 PPC PowerPC architecture is enabled.
72 PPT Parallel port support is enabled.
73 PS2 Appropriate PS/2 support is enabled.
74 RAM RAM disk support is enabled.
75 S390 S390 architecture is enabled.
76 SCSI Appropriate SCSI support is enabled.
77 A lot of drivers has their options described inside of
78 Documentation/scsi/.
79 SELINUX SELinux support is enabled.
80 SERIAL Serial support is enabled.
81 SMP The kernel is an SMP kernel.
82 SPARC Sparc architecture is enabled.
a9913044 83 SWSUSP Software suspend is enabled.
1da177e4
LT
84 TS Appropriate touchscreen support is enabled.
85 USB USB support is enabled.
86 USBHID USB Human Interface Device support is enabled.
87 V4L Video For Linux support is enabled.
88 VGA The VGA console has been enabled.
89 VT Virtual terminal support is enabled.
90 WDT Watchdog support is enabled.
91 XT IBM PC/XT MFM hard disk support is enabled.
92 X86-64 X86-64 architecture is enabled.
93 More X86-64 boot options can be found in
94 Documentation/x86_64/boot-options.txt .
95
96In addition, the following text indicates that the option:
97
98 BUGS= Relates to possible processor bugs on the said processor.
99 KNL Is a kernel start-up parameter.
100 BOOT Is a boot loader parameter.
101
102Parameters denoted with BOOT are actually interpreted by the boot
103loader, and have no meaning to the kernel directly.
104Do not modify the syntax of boot loader parameters without extreme
105need or coordination with <Documentation/i386/boot.txt>.
106
107Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
108a trailing = on the name of any parameter states that that parameter will
109be entered as an environment variable, whereas its absence indicates that
110it will appear as a kernel argument readable via /proc/cmdline by programs
111running once the system is up.
112
113 53c7xx= [HW,SCSI] Amiga SCSI controllers
114 See header of drivers/scsi/53c7xx.c.
115 See also Documentation/scsi/ncr53c7xx.txt.
116
a9913044
RD
117 acpi= [HW,ACPI] Advanced Configuration and Power Interface
118 Format: { force | off | ht | strict | noirq }
1da177e4
LT
119 force -- enable ACPI if default was off
120 off -- disable ACPI if default was on
121 noirq -- do not use ACPI for IRQ routing
122 ht -- run only enough ACPI to enable Hyper Threading
a9913044 123 strict -- Be less tolerant of platforms that are not
1da177e4
LT
124 strictly ACPI specification compliant.
125
126 See also Documentation/pm.txt, pci=noacpi
127
128 acpi_sleep= [HW,ACPI] Sleep options
129 Format: { s3_bios, s3_mode }
130 See Documentation/power/video.txt
a9913044 131
1da177e4 132 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 133 Format: { level | edge | high | low }
1da177e4 134
a9913044
RD
135 acpi_irq_balance [HW,ACPI]
136 ACPI will balance active IRQs
137 default in APIC mode
1da177e4 138
a9913044
RD
139 acpi_irq_nobalance [HW,ACPI]
140 ACPI will not move active IRQs (default)
141 default in PIC mode
1da177e4 142
a9913044
RD
143 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
144 use by PCI
1da177e4
LT
145 Format: <irq>,<irq>...
146
a9913044 147 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
1da177e4
LT
148 Format: <irq>,<irq>...
149
a1f9e65e
LB
150 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
151 Format: To spoof as Windows 98: ="Microsoft Windows"
152
1da177e4
LT
153 acpi_osi= [HW,ACPI] empty param disables _OSI
154
155 acpi_serialize [HW,ACPI] force serialization of AML methods
156
157 acpi_skip_timer_override [HW,ACPI]
158 Recognize and ignore IRQ0/pin2 Interrupt Override.
159 For broken nForce2 BIOS resulting in XT-PIC timer.
160
161 acpi_dbg_layer= [HW,ACPI]
162 Format: <int>
a9913044 163 Each bit of the <int> indicates an ACPI debug layer,
1da177e4
LT
164 1: enable, 0: disable. It is useful for boot time
165 debugging. After system has booted up, it can be set
166 via /proc/acpi/debug_layer.
167
168 acpi_dbg_level= [HW,ACPI]
169 Format: <int>
a9913044 170 Each bit of the <int> indicates an ACPI debug level,
1da177e4
LT
171 1: enable, 0: disable. It is useful for boot time
172 debugging. After system has booted up, it can be set
173 via /proc/acpi/debug_level.
174
175 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
176
30e332f3
LY
177 acpi_generic_hotkey [HW,ACPI]
178 Allow consolidated generic hotkey driver to
a9913044 179 override platform specific driver.
30e332f3
LY
180 See also Documentation/acpi-hotkey.txt.
181
5d0cf410
JS
182 acpi_pm_good [IA-32,X86-64]
183 Override the pmtimer bug detection: force the kernel
184 to assume that this machine's pmtimer latches its value
185 and always returns good values.
186
66759a01
CE
187 enable_timer_pin_1 [i386,x86-64]
188 Enable PIN 1 of APIC timer
a9913044
RD
189 Can be useful to work around chipset bugs
190 (in particular on some ATI chipsets).
66759a01
CE
191 The kernel tries to set a reasonable default.
192
193 disable_timer_pin_1 [i386,x86-64]
194 Disable PIN 1 of APIC timer
195 Can be useful to work around chipset bugs.
196
1da177e4
LT
197 ad1816= [HW,OSS]
198 Format: <io>,<irq>,<dma>,<dma2>
199 See also Documentation/sound/oss/AD1816.
200
201 ad1848= [HW,OSS]
202 Format: <io>,<irq>,<dma>,<dma2>,<type>
203
204 adlib= [HW,OSS]
205 Format: <io>
a9913044 206
1da177e4
LT
207 advansys= [HW,SCSI]
208 See header of drivers/scsi/advansys.c.
209
210 advwdt= [HW,WDT] Advantech WDT
211 Format: <iostart>,<iostop>
212
213 aedsp16= [HW,OSS] Audio Excel DSP 16
214 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
215 See also header of sound/oss/aedsp16.c.
a9913044 216
1da177e4
LT
217 aha152x= [HW,SCSI]
218 See Documentation/scsi/aha152x.txt.
219
220 aha1542= [HW,SCSI]
221 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
222
223 aic7xxx= [HW,SCSI]
224 See Documentation/scsi/aic7xxx.txt.
225
226 aic79xx= [HW,SCSI]
227 See Documentation/scsi/aic79xx.txt.
228
1da177e4
LT
229 amijoy.map= [HW,JOY] Amiga joystick support
230 Map of devices attached to JOY0DAT and JOY1DAT
231 Format: <a>,<b>
232 See also Documentation/kernel/input/joystick.txt
233
234 analog.map= [HW,JOY] Analog joystick and gamepad support
235 Specifies type or capabilities of an analog joystick
236 connected to one of 16 gameports
237 Format: <type1>,<type2>,..<type16>
238
a9913044
RD
239 apc= [HW,SPARC]
240 Power management functions (SPARCstation-4/5 + deriv.)
1da177e4
LT
241 Format: noidle
242 Disable APC CPU standby support. SPARCstation-Fox does
243 not play well with APC CPU idle - disable it if you have
244 APC and your system crashes randomly.
245
a9913044 246 apic= [APIC,i386] Change the output verbosity whilst booting
1da177e4
LT
247 Format: { quiet (default) | verbose | debug }
248 Change the amount of debugging information output
249 when initialising the APIC and IO-APIC components.
a9913044 250
1da177e4
LT
251 apm= [APM] Advanced Power Management
252 See header of arch/i386/kernel/apm.c.
253
254 applicom= [HW]
255 Format: <mem>,<irq>
a9913044 256
1da177e4
LT
257 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
258 Format: <io>,<irq>,<nodeID>
259
260 ataflop= [HW,M68k]
261
262 atarimouse= [HW,MOUSE] Atari Mouse
263
264 atascsi= [HW,SCSI] Atari SCSI
265
266 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
267 EzKey and similar keyboards
268
269 atkbd.reset= [HW] Reset keyboard during initialization
270
a9913044
RD
271 atkbd.set= [HW] Select keyboard code set
272 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
LT
273
274 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
275 keyboards
276
277 atkbd.softraw= [HW] Choose between synthetic and real raw mode
278 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
RD
279
280 atkbd.softrepeat= [HW]
281 Use software keyboard repeat
1da177e4
LT
282
283 autotest [IA64]
284
285 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
286 Format: <io>,<memsize>,<isapnp>
a9913044 287
1da177e4
LT
288 aztcd= [HW,CD] Aztech CD268 CDROM driver
289 Format: <io>,0x79 (?)
290
291 baycom_epp= [HW,AX25]
292 Format: <io>,<mode>
a9913044 293
1da177e4
LT
294 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
295 Format: <io>,<mode>
296 See header of drivers/net/hamradio/baycom_par.c.
297
a9913044
RD
298 baycom_ser_fdx= [HW,AX25]
299 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
1da177e4
LT
300 Format: <io>,<irq>,<mode>[,<baud>]
301 See header of drivers/net/hamradio/baycom_ser_fdx.c.
302
a9913044
RD
303 baycom_ser_hdx= [HW,AX25]
304 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
1da177e4
LT
305 Format: <io>,<irq>,<mode>
306 See header of drivers/net/hamradio/baycom_ser_hdx.c.
307
308 blkmtd_device= [HW,MTD]
309 blkmtd_erasesz=
310 blkmtd_ro=
311 blkmtd_bs=
312 blkmtd_count=
313
314 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
a9913044
RD
315 bttv.radio= Most important insmod options are available as
316 kernel args too.
1da177e4
LT
317 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
318 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
319
320 BusLogic= [HW,SCSI]
321 See drivers/scsi/BusLogic.c, comment before function
322 BusLogic_ParseDriverOptions().
323
324 c101= [NET] Moxa C101 synchronous serial card
325
326 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
327 Sometimes CPU hardware bugs make them report the cache
328 size incorrectly. The kernel will attempt work arounds
329 to fix known problems, but for some CPUs it is not
330 possible to determine what the correct size should be.
331 This option provides an override for these situations.
332
333 cdu31a= [HW,CD]
334 Format: <io>,<irq>[,PAS]
335 See header of drivers/cdrom/cdu31a.c.
336
337 chandev= [HW,NET] Generic channel device initialisation
338
339 checkreqprot [SELINUX] Set initial checkreqprot flag value.
340 Format: { "0" | "1" }
341 See security/selinux/Kconfig help text.
a9913044
RD
342 0 -- check protection applied by kernel (includes
343 any implied execute protection).
1da177e4
LT
344 1 -- check protection requested by application.
345 Default value is set via a kernel config option.
a9913044
RD
346 Value can be changed at runtime via
347 /selinux/checkreqprot.
348
734efb46
JS
349 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
350 [Deprecated]
351 Forces specified clocksource (if avaliable) to be used
352 when calculating gettimeofday(). If specified
353 clocksource is not avalible, it defaults to PIT.
1da177e4
LT
354 Format: { pit | tsc | cyclone | pmtmr }
355
f9262c12
AK
356 disable_8254_timer
357 enable_8254_timer
358 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
359 over the 8254 in addition to over the IO-APIC. The
360 kernel tries to set a sensible default.
361
1da177e4
LT
362 hpet= [IA-32,HPET] option to disable HPET and use PIT.
363 Format: disable
364
365 cm206= [HW,CD]
366 Format: { auto | [<io>,][<irq>] }
367
368 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
369 Format:
370 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
371
372 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
373 Format: <io>[,<irq>]
374
a9913044
RD
375 com90xx= [HW,NET]
376 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
377 Format: <io>[,<irq>[,<memstart>]]
378
379 condev= [HW,S390] console device
380 conmode=
a9913044 381
1da177e4
LT
382 console= [KNL] Output console device and options.
383
384 tty<n> Use the virtual console device <n>.
385
386 ttyS<n>[,options]
f1a1c2dc 387 ttyUSB0[,options]
1da177e4 388 Use the specified serial port. The options are of
f1a1c2dc
RD
389 the form "bbbbpnf", where "bbbb" is the baud rate,
390 "p" is parity ("n", "o", or "e"), "n" is number of
391 bits, and "f" is flow control ("r" for RTS or
392 omit it). Default is "9600n8".
393
394 See Documentation/serial-console.txt for more
395 information. See
396 Documentation/networking/netconsole.txt for an
397 alternative.
1da177e4
LT
398
399 uart,io,<addr>[,options]
400 uart,mmio,<addr>[,options]
401 Start an early, polled-mode console on the 8250/16550
402 UART at the specified I/O port or MMIO address,
403 switching to the matching ttyS device later. The
404 options are the same as for ttyS, above.
405
406 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
407 Format:
408 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4
LT
409
410 cpia_pp= [HW,PPT]
411 Format: { parport<nr> | auto | none }
412
dc009d92
EB
413 crashkernel=nn[KMG]@ss[KMG]
414 [KNL] Reserve a chunk of physical memory to
415 hold a kernel to switch to with kexec on panic.
416
1da177e4
LT
417 cs4232= [HW,OSS]
418 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
419
420 cs89x0_dma= [HW,NET]
421 Format: <dma>
422
423 cs89x0_media= [HW,NET]
424 Format: { rj45 | aui | bnc }
a9913044 425
1da177e4 426 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
a9913044
RD
427
428 dasd= [HW,NET]
1da177e4
LT
429 See header of drivers/s390/block/dasd_devmap.c.
430
431 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
432 (one device per port)
433 Format: <port#>,<type>
434 See also Documentation/input/joystick-parport.txt
435
436 debug [KNL] Enable kernel debugging (events log level).
437
cae2ed9a
IM
438 debug_locks_verbose=
439 [KNL] verbose self-tests
440 Format=<0|1>
441 Print debugging info while doing the locking API
442 self-tests.
443 We default to 0 (no extra messages), setting it to
444 1 will print _a lot_ more information - normally
445 only useful to kernel developers.
446
1da177e4
LT
447 decnet= [HW,NET]
448 Format: <area>[,<node>]
449 See also Documentation/networking/decnet.txt.
450
1da177e4
LT
451 dhash_entries= [KNL]
452 Set number of hash buckets for dentry cache.
a9913044 453
1da177e4
LT
454 digi= [HW,SERIAL]
455 IO parameters + enable/disable command.
456
457 digiepca= [HW,SERIAL]
458 See drivers/char/README.epca and
459 Documentation/digiepca.txt.
460
461 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
462 support available.
463 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
464
465 dmasound= [HW,OSS] Sound subsystem buffers
466
467 dscc4.setup= [NET]
468
469 dtc3181e= [HW,SCSI]
470
a9913044 471 earlyprintk= [IA-32,X86-64]
1da177e4
LT
472 earlyprintk=vga
473 earlyprintk=serial[,ttySn[,baudrate]]
474
a9913044 475 Append ",keep" to not disable it when the real console
1da177e4
LT
476 takes over.
477
478 Only vga or serial at a time, not both.
479
480 Currently only ttyS0 and ttyS1 are supported.
481
482 Interaction with the standard serial driver is not
483 very good.
484
485 The VGA output is eventually overwritten by the real
486 console.
487
488 eata= [HW,SCSI]
489
53f11d4f
LB
490 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
491 Format: <int>
492 0: polling mode
493 non-0: interrupt mode (default)
494
1da177e4
LT
495 eda= [HW,PS2]
496
497 edb= [HW,PS2]
498
499 edd= [EDD]
500 Format: {"of[f]" | "sk[ipmbr]"}
501 See comment in arch/i386/boot/edd.S
502
a9913044 503 eicon= [HW,ISDN]
1da177e4
LT
504 Format: <id>,<membase>,<irq>
505
506 eisa_irq_edge= [PARISC,HW]
507 See header of drivers/parisc/eisa.c.
508
509 elanfreq= [IA-32]
510 See comment before function elanfreq_setup() in
511 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
512
513 elevator= [IOSCHED]
16ab3adf 514 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
515 See Documentation/block/as-iosched.txt and
516 Documentation/block/deadline-iosched.txt for details.
517
aac04b32 518 elfcorehdr= [IA-32, X86_64]
a9913044 519 Specifies physical address of start of kernel core
aac04b32
VG
520 image elf header. Generally kexec loader will
521 pass this option to capture kernel.
522 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
523
524 enforcing [SELINUX] Set initial enforcing status.
525 Format: {"0" | "1"}
526 See security/selinux/Kconfig help text.
527 0 -- permissive (log only, no denials).
528 1 -- enforcing (deny and log).
529 Default value is 0.
530 Value can be changed at runtime via /selinux/enforce.
531
532 es1370= [HW,OSS]
533 Format: <lineout>[,<micbias>]
534 See also header of sound/oss/es1370.c.
535
536 es1371= [HW,OSS]
537 Format: <spdif>,[<nomix>,[<amplifier>]]
538 See also header of sound/oss/es1371.c.
a9913044 539
1da177e4
LT
540 ether= [HW,NET] Ethernet cards parameters
541 This option is obsoleted by the "netdev=" option, which
542 has equivalent usage. See its documentation for details.
543
544 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
545 Format: <io>[,<irq>]
546
547 fd_mcs= [HW,SCSI]
548 See header of drivers/scsi/fd_mcs.c.
549
550 fdomain= [HW,SCSI]
551 See header of drivers/scsi/fdomain.c.
552
553 floppy= [HW]
554 See Documentation/floppy.txt.
555
556 ftape= [HW] Floppy Tape subsystem debugging options.
557 See Documentation/ftape.txt.
558
559 gamecon.map[2|3]=
560 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
561 support via parallel port (up to 5 devices per port)
562 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
563 See also Documentation/input/joystick-parport.txt
564
565 gamma= [HW,DRM]
566
567 gdth= [HW,SCSI]
568 See header of drivers/scsi/gdth.c.
569
570 gpt [EFI] Forces disk with valid GPT signature but
571 invalid Protective MBR to be treated as GPT.
572
573 gscd= [HW,CD]
574 Format: <io>
575
1da177e4
LT
576 gus= [HW,OSS]
577 Format: <io>,<irq>,<dma>,<dma16>
a9913044 578
1da177e4
LT
579 gvp11= [HW,SCSI]
580
581 hashdist= [KNL,NUMA] Large hashes allocated during boot
582 are distributed across NUMA nodes. Defaults on
583 for IA-64, off otherwise.
a9913044 584 Format: 0 | 1 (for off | on)
1da177e4
LT
585
586 hcl= [IA-64] SGI's Hardware Graph compatibility layer
587
588 hd= [EIDE] (E)IDE hard drive subsystem geometry
589 Format: <cyl>,<head>,<sect>
590
591 hd?= [HW] (E)IDE subsystem
592 hd?lun= See Documentation/ide.txt.
593
594 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
595 size of <nn>. This works even on boxes that have no
596 highmem otherwise. This also works to reduce highmem
597 size on bigger boxes.
598
599 hisax= [HW,ISDN]
600 See Documentation/isdn/README.HiSax.
601
602 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
603
604 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
605
606 i8042.direct [HW] Put keyboard port into non-translated mode
607 i8042.dumbkbd [HW] Pretend that controlled can only read data from
608 keyboard and can not control its state
609 (Don't attempt to blink the leds)
610 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 611 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
612 i8042.nomux [HW] Don't check presence of an active multiplexing
613 controller
614 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
615 controllers
616 i8042.panicblink=
617 [HW] Frequency with which keyboard LEDs should blink
618 when kernel panics (default is 0.5 sec)
619 i8042.reset [HW] Reset the controller during init and cleanup
620 i8042.unlock [HW] Unlock (ignore) the keylock
621
622 i810= [HW,DRM]
623
e70c9d5e
DT
624 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
625 indicates that the driver is running on unsupported
626 hardware.
1da177e4
LT
627 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
628 does not match list of supported models.
629 i8k.power_status
630 [HW] Report power status in /proc/i8k
631 (disabled by default)
632 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
633 capability is set.
634
635 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
636 See Documentation/mca.txt.
637
638 icn= [HW,ISDN]
639 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
640
641 ide= [HW] (E)IDE subsystem
642 Format: ide=nodma or ide=doubler or ide=reverse
643 See Documentation/ide.txt.
644
645 ide?= [HW] (E)IDE subsystem
646 Format: ide?=noprobe or chipset specific parameters.
647 See Documentation/ide.txt.
a9913044 648
1da177e4
LT
649 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
650 See Documentation/ide.txt.
651
652 idle= [HW]
653 Format: idle=poll or idle=halt
a9913044 654
1da177e4
LT
655 ihash_entries= [KNL]
656 Set number of hash buckets for inode cache.
657
658 in2000= [HW,SCSI]
659 See header of drivers/scsi/in2000.c.
660
661 init= [KNL]
662 Format: <full_path>
663 Run specified binary instead of /sbin/init as init
664 process.
665
666 initcall_debug [KNL] Trace initcalls as they are executed. Useful
667 for working out where the kernel is dying during
668 startup.
669
670 initrd= [BOOT] Specify the location of the initial ramdisk
671
672 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
673 Format: <irq>
674
2bd0fa3b
JB
675 combined_mode= [HW] control which driver uses IDE ports in combined
676 mode: legacy IDE driver, libata, or both
677 (in the libata case, libata.atapi_enabled=1 may be
678 useful as well). Note that using the ide or libata
679 options may affect your device naming (e.g. by
680 changing hdc to sdb).
681 Format: combined (default), ide, or libata
682
1da177e4
LT
683 inttest= [IA64]
684
685 io7= [HW] IO7 for Marvel based alpha systems
686 See comment before marvel_specify_io7 in
687 arch/alpha/kernel/core_marvel.c.
688
689 ip= [IP_PNP]
690 See Documentation/nfsroot.txt.
691
692 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
693 See comment before ip2_setup() in drivers/char/ip2.c.
694
695 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
696 See header of drivers/scsi/ips.c.
697
72c4a13a
SH
698 ports= [IP_VS_FTP] IPVS ftp helper module
699 Default is 21.
700 Up to 8 (IP_VS_APP_MAX_PORTS) ports
701 may be specified.
702 Format: <port>,<port>....
703
200803df
AC
704 irqfixup [HW]
705 When an interrupt is not handled search all handlers
706 for it. Intended to get systems with badly broken
707 firmware running.
708
709 irqpoll [HW]
710 When an interrupt is not handled search all handlers
711 for it. Also check all handlers each timer
712 interrupt. Intended to get systems with badly broken
713 firmware running.
714
1da177e4 715 isapnp= [ISAPNP]
a9913044 716 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
717
718 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
719 Format: <cpu number>,...,<cpu number>
720 This option can be used to specify one or more CPUs
721 to isolate from the general SMP balancing and scheduling
722 algorithms. The only way to move a process onto or off
723 an "isolated" CPU is via the CPU affinity syscalls.
724 <cpu number> begins at 0 and the maximum value is
725 "number of CPUs in system - 1".
726
727 This option is the preferred way to isolate CPUs. The
a9913044
RD
728 alternative -- manually setting the CPU mask of all
729 tasks in the system -- can cause problems and
730 suboptimal load balancer performance.
1da177e4
LT
731
732 isp16= [HW,CD]
733 Format: <io>,<irq>,<dma>,<setup>
734
a9913044 735 iucv= [HW,NET]
1da177e4
LT
736
737 js= [HW,JOY] Analog joystick
738 See Documentation/input/joystick.txt.
739
740 keepinitrd [HW,ARM]
741
a9913044 742 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
743 in oops dumps.
744
745 l2cr= [PPC]
746
a9913044
RD
747 lapic [IA-32,APIC] Enable the local APIC even if BIOS
748 disabled it.
1da177e4
LT
749
750 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
751 Format: addr:<io>,irq:<irq>
752
a9913044
RD
753 llsc*= [IA64] See function print_params() in
754 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
755
756 load_ramdisk= [RAM] List of ramdisks to load from floppy
757 See Documentation/ramdisk.txt.
758
a6b25b67
RD
759 lockd.nlm_grace_period=P [NFS] Assign grace period.
760 Format: <integer>
1da177e4 761
a6b25b67
RD
762 lockd.nlm_tcpport=N [NFS] Assign TCP port.
763 Format: <integer>
764
765 lockd.nlm_timeout=T [NFS] Assign timeout value.
766 Format: <integer>
767
768 lockd.nlm_udpport=M [NFS] Assign UDP port.
769 Format: <integer>
1da177e4
LT
770
771 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
772 Format: <irq>
773
774 loglevel= All Kernel Messages with a loglevel smaller than the
775 console loglevel will be printed to the console. It can
776 also be changed with klogd or other programs. The
777 loglevels are defined as follows:
778
779 0 (KERN_EMERG) system is unusable
780 1 (KERN_ALERT) action must be taken immediately
781 2 (KERN_CRIT) critical conditions
782 3 (KERN_ERR) error conditions
783 4 (KERN_WARNING) warning conditions
784 5 (KERN_NOTICE) normal but significant condition
785 6 (KERN_INFO) informational
786 7 (KERN_DEBUG) debug-level messages
787
788 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
789 Format: { n | nk | nM }
790 n must be a power of two. The default size
791 is set in the kernel config file.
1da177e4
LT
792
793 lp=0 [LP] Specify parallel ports to use, e.g,
794 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
795 lp=reset first parallel port). 'lp=0' disables the
796 lp=auto printer driver. 'lp=reset' (which can be
797 specified in addition to the ports) causes
798 attached printers to be reset. Using
799 lp=port1,port2,... specifies the parallel ports
800 to associate lp devices with, starting with
801 lp0. A port specification may be 'none' to skip
802 that lp device, or a parport name such as
803 'parport0'. Specifying 'lp=auto' instead of a
804 port specification list means that device IDs
805 from each port should be examined, to see if
806 an IEEE 1284-compliant printer is attached; if
807 so, the driver will manage that printer.
808 See also header of drivers/char/lp.c.
809
810 lpj=n [KNL]
811 Sets loops_per_jiffy to given constant, thus avoiding
812 time-consuming boot-time autodetection (up to 250 ms per
813 CPU). 0 enables autodetection (default). To determine
814 the correct value for your kernel, boot with normal
815 autodetection and see what value is printed. Note that
816 on SMP systems the preset will be applied to all CPUs,
817 which is likely to cause problems if your CPUs need
818 significantly divergent settings. An incorrect value
819 will cause delays in the kernel to be wrong, leading to
820 unpredictable I/O errors and other breakage. Although
821 unlikely, in the extreme case this might damage your
822 hardware.
823
824 ltpc= [NET]
825 Format: <io>,<irq>,<dma>
826
a9913044
RD
827 mac5380= [HW,SCSI] Format:
828 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 829
a9913044
RD
830 mac53c9x= [HW,SCSI] Format:
831 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 832
a9913044
RD
833 machvec= [IA64] Force the use of a particular machine-vector
834 (machvec) in a generic kernel.
835 Example: machvec=hpzx1_swiotlb
1da177e4 836
a9913044
RD
837 mad16= [HW,OSS] Format:
838 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
839
840 maui= [HW,OSS]
841 Format: <io>,<irq>
a9913044
RD
842
843 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
844 be mounted
845 Format: <1-256>
846
847 maxcpus= [SMP] Maximum number of processors that an SMP kernel
848 should make use of
849
2b2c3750
BP
850 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
851 equal to this physical address is ignored.
852
a9913044 853 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
854 Should be between 1 and 2^32-1.
855
856 max_report_luns=
a9913044 857 [SCSI] Maximum number of LUNs received.
1da177e4
LT
858 Should be between 1 and 16384.
859
860 mca-pentium [BUGS=IA-32]
861
862 mcatest= [IA-64]
863
864 mcd= [HW,CD]
865 Format: <port>,<irq>,<mitsumi_bug_93_wait>
866
867 mcdx= [HW,CD]
868
869 mce [IA-32] Machine Check Exception
870
871 md= [HW] RAID subsystems devices and level
872 See Documentation/md.txt.
a9913044 873
1da177e4
LT
874 mdacon= [MDA]
875 Format: <first>,<last>
876 Specifies range of consoles to be captured by the MDA.
a9913044 877
1da177e4
LT
878 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
879 Amount of memory to be used when the kernel is not able
880 to see the whole system memory or for test.
881 [IA-32] Use together with memmap= to avoid physical
882 address space collisions. Without memmap= PCI devices
883 could be placed at addresses belonging to unused RAM.
884
885 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
886 memory.
887
69cda7b1 888 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
889 E820 memory map, as specified by the user.
890 Such memmap=exactmap lines can be constructed based on
891 BIOS output or other requirements. See the memmap=nn@ss
892 option description.
893
894 memmap=nn[KMG]@ss[KMG]
895 [KNL] Force usage of a specific region of memory
896 Region of memory to be used, from ss to ss+nn.
897
898 memmap=nn[KMG]#ss[KMG]
899 [KNL,ACPI] Mark specific memory as ACPI data.
900 Region of memory to be used, from ss to ss+nn.
901
902 memmap=nn[KMG]$ss[KMG]
903 [KNL,ACPI] Mark specific memory as reserved.
904 Region of memory to be used, from ss to ss+nn.
905
906 meye.*= [HW] Set MotionEye Camera parameters
907 See Documentation/video4linux/meye.txt.
908
909 mga= [HW,DRM]
910
198e2f18
AM
911 migration_cost=
912 [KNL,SMP] debug: override scheduler migration costs
913 Format: <level-1-usecs>,<level-2-usecs>,...
914 This debugging option can be used to override the
915 default scheduler migration cost matrix. The numbers
916 are indexed by 'CPU domain distance'.
917 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
918 box will set up an intra-core migration cost of
919 1 msec, an inter-core migration cost of 2 msecs,
920 and an inter-node migration cost of 3 msecs.
921
922 WARNING: using the wrong values here can break
923 scheduler performance, so it's only for scheduler
924 development purposes, not production environments.
925
926 migration_debug=
927 [KNL,SMP] migration cost auto-detect verbosity
928 Format=<0|1|2>
929 If a system's migration matrix reported at bootup
930 seems erroneous then this option can be used to
931 increase verbosity of the detection process.
932 We default to 0 (no extra messages), 1 will print
933 some more information, and 2 will be really
934 verbose (probably only useful if you also have a
935 serial console attached to the system).
936
937 migration_factor=
938 [KNL,SMP] multiply/divide migration costs by a factor
939 Format=<percent>
940 This debug option can be used to proportionally
941 increase or decrease the auto-detected migration
942 costs for all entries of the migration matrix.
943 E.g. migration_factor=150 will increase migration
944 costs by 50%. (and thus the scheduler will be less
945 eager migrating cache-hot tasks)
946 migration_factor=80 will decrease migration costs
947 by 20%. (thus the scheduler will be more eager to
948 migrate tasks)
949
950 WARNING: using the wrong values here can break
951 scheduler performance, so it's only for scheduler
952 development purposes, not production environments.
953
1da177e4
LT
954 mousedev.tap_time=
955 [MOUSE] Maximum time between finger touching and
956 leaving touchpad surface for touch to be considered
957 a tap and be reported as a left button click (for
958 touchpads working in absolute mode only).
959 Format: <msecs>
960 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
961 reporting absolute coordinates, such as tablets
962 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
963 reporting absolute coordinates, such as tablets
964
965 mpu401= [HW,OSS]
966 Format: <io>,<irq>
967
968 MTD_Partition= [MTD]
969 Format: <name>,<region-number>,<size>,<offset>
970
a9913044
RD
971 MTD_Region= [MTD] Format:
972 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
973
974 mtdparts= [MTD]
975 See drivers/mtd/cmdline.c.
976
977 mtouchusb.raw_coordinates=
a9913044
RD
978 [HW] Make the MicroTouch USB driver use raw coordinates
979 ('y', default) or cooked coordinates ('n')
1da177e4
LT
980
981 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
982
983 NCR_D700= [HW,SCSI]
984 See header of drivers/scsi/NCR_D700.c.
985
986 ncr5380= [HW,SCSI]
987
988 ncr53c400= [HW,SCSI]
989
990 ncr53c400a= [HW,SCSI]
991
992 ncr53c406a= [HW,SCSI]
993
994 ncr53c8xx= [HW,SCSI]
995
996 netdev= [NET] Network devices parameters
997 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
998 Note that mem_start is often overloaded to mean
999 something different and driver-specific.
a9913044
RD
1000 This usage is only documented in each driver source
1001 file if at all.
1002
1da177e4
LT
1003 nfsaddrs= [NFS]
1004 See Documentation/nfsroot.txt.
1005
1006 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1007 See Documentation/nfsroot.txt.
1008
a72b4422
TM
1009 nfs.callback_tcpport=
1010 [NFS] set the TCP port on which the NFSv4 callback
1011 channel should listen.
1012
58df095b
TM
1013 nfs.idmap_cache_timeout=
1014 [NFS] set the maximum lifetime for idmapper cache
1015 entries.
1016
1da177e4
LT
1017 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1018
1019 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1020 emulation library even if a 387 maths coprocessor
1021 is present.
1022
a9913044
RD
1023 noalign [KNL,ARM]
1024
1da177e4
LT
1025 noapic [SMP,APIC] Tells the kernel to not make use of any
1026 IOAPICs that may be present in the system.
1027
1028 noasync [HW,M68K] Disables async and sync negotiation for
1029 all devices.
1030
1031 nobats [PPC] Do not use BATs for mapping kernel lowmem
1032 on "Classic" PPC cores.
1033
1034 nocache [ARM]
a9913044 1035
163ecdff
SN
1036 nodelayacct [KNL] Disable per-task delay accounting
1037
1da177e4
LT
1038 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1039
1040 noexec [IA-64]
1041
a9913044 1042 noexec [IA-32,X86-64]
1da177e4
LT
1043 noexec=on: enable non-executable mappings (default)
1044 noexec=off: disable nn-executable mappings
1045
4f886511
CE
1046 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1047 register save and restore. The kernel will only save
1048 legacy floating-point registers on task switch.
1da177e4
LT
1049
1050 nohlt [BUGS=ARM]
a9913044 1051
1da177e4
LT
1052 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1053 instruction doesn't work correctly and not to
1054 use it.
1055
1056 nohalt [IA-64] Tells the kernel not to use the power saving
1057 function PAL_HALT_LIGHT when idle. This increases
1058 power-consumption. On the positive side, it reduces
1059 interrupt wake-up latency, which may improve performance
1060 in certain environments such as networked servers or
1061 real-time systems.
1062
1063 noirqdebug [IA-32] Disables the code which attempts to detect and
1064 disable unhandled interrupt sources.
1065
1066 noisapnp [ISAPNP] Disables ISA PnP code.
1067
1068 noinitrd [RAM] Tells the kernel not to load any configured
1069 initial RAM disk.
1070
1071 nointroute [IA-64]
1072
1073 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1074
1075 noltlbs [PPC] Do not use large page/tlb entries for kernel
1076 lowmem mapping on PPC40x.
1077
312f1f01
H
1078 nomca [IA-64] Disable machine check abort handling
1079
abe37e5a
H
1080 nomce [IA-32] Machine Check Exception
1081
1da177e4
LT
1082 noresidual [PPC] Don't use residual data on PReP machines.
1083
a9913044
RD
1084 noresume [SWSUSP] Disables resume and restores original swap
1085 space.
1086
1da177e4
LT
1087 no-scroll [VGA] Disables scrollback.
1088 This is required for the Braillex ib80-piezo Braille
1089 reader made by F.H. Papenmeier (Germany).
1090
1091 nosbagart [IA-64]
1092
4f886511
CE
1093 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1094
1da177e4
LT
1095 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1096
1097 nosync [HW,M68K] Disables sync negotiation for all devices.
1098
1099 notsc [BUGS=IA-32] Disable Time Stamp Counter
1100
1101 nousb [USB] Disable the USB subsystem
1102
1103 nowb [ARM]
a9913044 1104
a61c2d78
DJ
1105 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1106
1da177e4
LT
1107 opl3= [HW,OSS]
1108 Format: <io>
1109
1110 opl3sa= [HW,OSS]
1111 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1112
a9913044
RD
1113 opl3sa2= [HW,OSS] Format:
1114 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1115
1da177e4
LT
1116 oprofile.timer= [HW]
1117 Use timer interrupt instead of performance counters
1118
1119 optcd= [HW,CD]
1120 Format: <io>
1121
1122 osst= [HW,SCSI] SCSI Tape Driver
1123 Format: <buffer_size>,<write_threshold>
1124 See also Documentation/scsi/st.txt.
1125
1126 panic= [KNL] Kernel behaviour on panic
1127 Format: <timeout>
1128
1129 parkbd.port= [HW] Parallel port number the keyboard adapter is
1130 connected to, default is 0.
1131 Format: <parport#>
1132 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1133 0 for XT, 1 for AT (default is AT).
a9913044
RD
1134 Format: <mode>
1135
1136 parport= [HW,PPT] Specify parallel ports. 0 disables.
1137 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1138 Use 'auto' to force the driver to use any
1139 IRQ/DMA settings detected (the default is to
1140 ignore detected IRQ/DMA settings because of
1141 possible conflicts). You can specify the base
1142 address, IRQ, and DMA settings; IRQ and DMA
1143 should be numbers, or 'auto' (for using detected
1144 settings on that particular port), or 'nofifo'
1145 (to avoid using a FIFO even if it is detected).
1146 Parallel ports are assigned in the order they
1147 are specified on the command line, starting
1148 with parport0.
1149
1150 parport_init_mode= [HW,PPT]
1151 Configure VIA parallel port to operate in
1152 a specific mode. This is necessary on Pegasos
1153 computer where firmware has no options for setting
1154 up parallel port mode and sets it to spp.
1155 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1156 Format: [spp|ps2|epp|ecp|ecpepp]
1157
a9913044
RD
1158 pas2= [HW,OSS] Format:
1159 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1160
1da177e4
LT
1161 pas16= [HW,SCSI]
1162 See header of drivers/scsi/pas16.c.
1163
dd287796
AM
1164 pause_on_oops=
1165 Halt all CPUs after the first oops has been printed for
1166 the specified number of seconds. This is to be used if
1167 your oopses keep scrolling off the screen.
1168
1da177e4
LT
1169 pcbit= [HW,ISDN]
1170
1171 pcd. [PARIDE]
1172 See header of drivers/block/paride/pcd.c.
1173 See also Documentation/paride.txt.
1174
a9913044
RD
1175 pci=option[,option...] [PCI] various PCI subsystem options:
1176 off [IA-32] don't probe for the PCI bus
1177 bios [IA-32] force use of PCI BIOS, don't access
1178 the hardware directly. Use this if your machine
1179 has a non-standard PCI host bridge.
1180 nobios [IA-32] disallow use of PCI BIOS, only direct
1181 hardware access methods are allowed. Use this
1182 if you experience crashes upon bootup and you
1183 suspect they are caused by the BIOS.
1184 conf1 [IA-32] Force use of PCI Configuration
1185 Mechanism 1.
1186 conf2 [IA-32] Force use of PCI Configuration
1187 Mechanism 2.
61be6d66
BH
1188 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1189 Configuration
309e57df
MW
1190 nomsi [MSI] If the PCI_MSI kernel config parameter is
1191 enabled, this kernel boot option can be used to
1192 disable the use of MSI interrupts system-wide.
a9913044
RD
1193 nosort [IA-32] Don't sort PCI devices according to
1194 order given by the PCI BIOS. This sorting is
1195 done to get a device order compatible with
1196 older kernels.
1197 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1198 routing table. These calls are known to be buggy
1199 on several machines and they hang the machine
1200 when used, but on other computers it's the only
1201 way to get the interrupt routing table. Try
1202 this option if the kernel is unable to allocate
1203 IRQs or discover secondary PCI buses on your
1204 motherboard.
1205 rom [IA-32] Assign address space to expansion ROMs.
1206 Use with caution as certain devices share
1207 address decoders between ROMs and other
1208 resources.
1209 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1210 assigned automatically to PCI devices. You can
1211 make the kernel exclude IRQs of your ISA cards
1212 this way.
120bb424 1213 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1214 of the PIRQ table (normally generated
1215 by the BIOS) if it is outside the
1216 F0000h-100000h range.
1217 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1218 useful if the kernel is unable to find your
1219 secondary buses and you want to tell it
1220 explicitly which ones they are.
1221 assign-busses [IA-32] Always assign all PCI bus
1222 numbers ourselves, overriding
1223 whatever the firmware may have done.
1224 usepirqmask [IA-32] Honor the possible IRQ mask stored
1225 in the BIOS $PIR table. This is needed on
1226 some systems with broken BIOSes, notably
1227 some HP Pavilion N5400 and Omnibook XE3
1228 notebooks. This will have no effect if ACPI
1229 IRQ routing is enabled.
1230 noacpi [IA-32] Do not use ACPI for IRQ routing
1231 or for PCI scanning.
1232 routeirq Do IRQ routing for all PCI devices.
1233 This is normally done in pci_enable_device(),
1234 so this option is a temporary workaround
1235 for broken drivers that don't call it.
1236 firmware [ARM] Do not re-enumerate the bus but instead
1237 just use the configuration from the
1238 bootloader. This is currently used on
1239 IXP2000 systems where the bus has to be
1240 configured a certain way for adjunct CPUs.
0637a70a
AK
1241 noearly [X86] Don't do any early type 1 scanning.
1242 This might help on some broken boards which
1243 machine check when some devices' config space
1244 is read. But various workarounds are disabled
1245 and some IOMMU drivers will not work.
1da177e4
LT
1246 pcmv= [HW,PCMCIA] BadgePAD 4
1247
1248 pd. [PARIDE]
1249 See Documentation/paride.txt.
1250
1251 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1252 boot time.
1253 Format: { 0 | 1 }
1254 See arch/parisc/kernel/pdc_chassis.c
1255
1256 pf. [PARIDE]
1257 See Documentation/paride.txt.
1258
1259 pg. [PARIDE]
1260 See Documentation/paride.txt.
1261
1262 pirq= [SMP,APIC] Manual mp-table setup
1263 See Documentation/i386/IO-APIC.txt.
1264
1265 plip= [PPT,NET] Parallel port network link
1266 Format: { parport<nr> | timid | 0 }
1267 See also Documentation/parport.txt.
1268
1269 pnpacpi= [ACPI]
1270 { off }
1271
1272 pnpbios= [ISAPNP]
1273 { on | off | curr | res | no-curr | no-res }
1274
1275 pnp_reserve_irq=
1276 [ISAPNP] Exclude IRQs for the autoconfiguration
1277
1278 pnp_reserve_dma=
1279 [ISAPNP] Exclude DMAs for the autoconfiguration
1280
1281 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1282 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1283
1284 pnp_reserve_mem=
a9913044
RD
1285 [ISAPNP] Exclude memory regions for the
1286 autoconfiguration.
1da177e4
LT
1287 Ranges are in pairs (memory base and size).
1288
1289 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1290 Format: [schedule,]<number>
1291 Param: "schedule" - profile schedule points.
1292 Param: <number> - step/bucket size as a power of 2 for
1293 statistical time based profiling.
1da177e4 1294
a9913044 1295 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1296 Limit processor to maximum C-state
1297 max_cstate=9 overrides any DMI blacklist limit.
1298
41c0d868
LB
1299 processor.nocst [HW,ACPI]
1300 Ignore the _CST method to determine C-states,
1301 instead using the legacy FADT method
1302
1da177e4
LT
1303 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1304 before loading.
1305 See Documentation/ramdisk.txt.
1306
a9913044
RD
1307 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1308 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1309 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1310 per second.
a9913044
RD
1311 psmouse.resetafter= [HW,MOUSE]
1312 Try to reset the device after so many bad packets
1da177e4
LT
1313 (0 = never).
1314 psmouse.resolution=
1315 [HW,MOUSE] Set desired mouse resolution, in dpi.
1316 psmouse.smartscroll=
a9913044 1317 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1318 0 = disabled, 1 = enabled (default).
1319
1320 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1321 Format:
1322 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1323
1324 pt. [PARIDE]
1325 See Documentation/paride.txt.
1326
1327 quiet= [KNL] Disable log messages
a9913044 1328
1da177e4
LT
1329 r128= [HW,DRM]
1330
1331 raid= [HW,RAID]
1332 See Documentation/md.txt.
1333
1334 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1335 See Documentation/ramdisk.txt.
1336
a9913044 1337 ramdisk_blocksize= [RAM]
1da177e4 1338 See Documentation/ramdisk.txt.
a9913044 1339
1da177e4
LT
1340 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1341 New name for the ramdisk parameter.
1342 See Documentation/ramdisk.txt.
1343
21a1ea9e
DS
1344 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1345 RCU callbacks to process in one batch.
1346
1347 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1348 RCU callbacks over which batch limiting is disabled.
1349
1350 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1351 RCU callbacks below which batch limiting is re-enabled.
1352
1353 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1354 RCU callbacks to queued before forcing reschedule
1355 on all cpus.
1356
ffdfc409
OJ
1357 rdinit= [KNL]
1358 Format: <full_path>
1359 Run specified binary instead of /init from the ramdisk,
1360 used for early userspace startup. See initrd.
1361
1da177e4
LT
1362 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1363 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1364 See arch/*/kernel/reboot.c.
1365
1366 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1367
461a9aff
ZA
1368 reservetop= [IA-32]
1369 Format: nn[KMG]
1370 Reserves a hole at the top of the kernel virtual
1371 address space.
1372
7e96287d
VG
1373 reset_devices [KNL] Force drivers to reset the underlying device
1374 during initialization.
1375
a9913044
RD
1376 resume= [SWSUSP]
1377 Specify the partition device for software suspend
1da177e4
LT
1378
1379 rhash_entries= [KNL,NET]
1380 Set number of hash buckets for route cache
1381
1382 riscom8= [HW,SERIAL]
1383 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1384
1385 ro [KNL] Mount root device read-only on boot
1386
1387 root= [KNL] Root filesystem
1388
1389 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1390 mount the root filesystem
1391
1392 rootflags= [KNL] Set root filesystem mount option string
1393
1394 rootfstype= [KNL] Set root filesystem type
1395
1396 rw [KNL] Mount root device read-write on boot
1397
1398 S [KNL] Run init in single mode
1399
1400 sa1100ir [NET]
1401 See drivers/net/irda/sa1100_ir.c.
1402
1403 sb= [HW,OSS]
1404 Format: <io>,<irq>,<dma>,<dma2>
1405
1406 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1407
1da177e4
LT
1408 sbpcd= [HW,CD] Soundblaster CD adapter
1409 Format: <io>,<type>
1410 See a comment before function sbpcd_setup() in
1411 drivers/cdrom/sbpcd.c.
1412
1413 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1414 Format: <io>[,<timeout>[,<isapnp>]]
1415
1416 scsi_debug_*= [SCSI]
1417 See drivers/scsi/scsi_debug.c.
1418
1419 scsi_default_dev_flags=
1420 [SCSI] SCSI default device flags
1421 Format: <integer>
1422
1423 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1424 Format: <vendor>:<model>:<flags>
1425 (flags are integer value)
1426
1427 scsi_logging= [SCSI]
1428
1429 selinux [SELINUX] Disable or enable SELinux at boot time.
1430 Format: { "0" | "1" }
1431 See security/selinux/Kconfig help text.
1432 0 -- disable.
1433 1 -- enable.
1434 Default value is set via kernel config option.
1435 If enabled at boot time, /selinux/disable can be used
1436 later to disable prior to initial policy load.
1437
4e5ab4cb
JM
1438 selinux_compat_net =
1439 [SELINUX] Set initial selinux_compat_net flag value.
1440 Format: { "0" | "1" }
1441 0 -- use new secmark-based packet controls
1442 1 -- use legacy packet controls
1443 Default value is 0 (preferred).
1444 Value can be changed at runtime via
1445 /selinux/compat_net.
1446
1da177e4
LT
1447 serialnumber [BUGS=IA-32]
1448
a9913044
RD
1449 sg_def_reserved_size= [SCSI]
1450
1da177e4
LT
1451 sgalaxy= [HW,OSS]
1452 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1453
1454 shapers= [NET]
1455 Maximal number of shapers.
a9913044 1456
1da177e4
LT
1457 sim710= [SCSI,HW]
1458 See header of drivers/scsi/sim710.c.
1459
1460 simeth= [IA-64]
1461 simscsi=
a9913044 1462
1da177e4
LT
1463 sjcd= [HW,CD]
1464 Format: <io>,<irq>,<dma>
1465 See header of drivers/cdrom/sjcd.c.
1466
1467 slram= [HW,MTD]
1468
1469 smart2= [HW]
1470 Format: <io1>[,<io2>[,...,<io8>]]
1471
1472 snd-ad1816a= [HW,ALSA]
1473
1474 snd-ad1848= [HW,ALSA]
1475
1476 snd-ali5451= [HW,ALSA]
1477
1478 snd-als100= [HW,ALSA]
1479
1480 snd-als4000= [HW,ALSA]
1481
1482 snd-azt2320= [HW,ALSA]
1483
1484 snd-cmi8330= [HW,ALSA]
1485
1486 snd-cmipci= [HW,ALSA]
1487
1488 snd-cs4231= [HW,ALSA]
1489
1490 snd-cs4232= [HW,ALSA]
1491
1492 snd-cs4236= [HW,ALSA]
1493
1494 snd-cs4281= [HW,ALSA]
1495
1496 snd-cs46xx= [HW,ALSA]
1497
1498 snd-dt019x= [HW,ALSA]
1499
1500 snd-dummy= [HW,ALSA]
1501
1502 snd-emu10k1= [HW,ALSA]
1503
1504 snd-ens1370= [HW,ALSA]
1505
1506 snd-ens1371= [HW,ALSA]
1507
1508 snd-es968= [HW,ALSA]
1509
1510 snd-es1688= [HW,ALSA]
1511
1512 snd-es18xx= [HW,ALSA]
1513
1514 snd-es1938= [HW,ALSA]
1515
1516 snd-es1968= [HW,ALSA]
1517
1518 snd-fm801= [HW,ALSA]
1519
1520 snd-gusclassic= [HW,ALSA]
1521
1522 snd-gusextreme= [HW,ALSA]
1523
1524 snd-gusmax= [HW,ALSA]
1525
1526 snd-hdsp= [HW,ALSA]
1527
1528 snd-ice1712= [HW,ALSA]
1529
1530 snd-intel8x0= [HW,ALSA]
1531
1532 snd-interwave= [HW,ALSA]
1533
1534 snd-interwave-stb=
1535 [HW,ALSA]
1536
1537 snd-korg1212= [HW,ALSA]
1538
1539 snd-maestro3= [HW,ALSA]
1540
1541 snd-mpu401= [HW,ALSA]
1542
1543 snd-mtpav= [HW,ALSA]
1544
1545 snd-nm256= [HW,ALSA]
1546
1547 snd-opl3sa2= [HW,ALSA]
1548
1549 snd-opti92x-ad1848=
1550 [HW,ALSA]
1551
1552 snd-opti92x-cs4231=
1553 [HW,ALSA]
1554
1555 snd-opti93x= [HW,ALSA]
1556
1557 snd-pmac= [HW,ALSA]
1558
1559 snd-rme32= [HW,ALSA]
1560
1561 snd-rme96= [HW,ALSA]
1562
1563 snd-rme9652= [HW,ALSA]
1564
1565 snd-sb8= [HW,ALSA]
1566
1567 snd-sb16= [HW,ALSA]
1568
1569 snd-sbawe= [HW,ALSA]
1570
1571 snd-serial= [HW,ALSA]
1572
1573 snd-sgalaxy= [HW,ALSA]
1574
1575 snd-sonicvibes= [HW,ALSA]
1576
1577 snd-sun-amd7930=
1578 [HW,ALSA]
1579
1580 snd-sun-cs4231= [HW,ALSA]
1581
1582 snd-trident= [HW,ALSA]
1583
1584 snd-usb-audio= [HW,ALSA,USB]
1585
1586 snd-via82xx= [HW,ALSA]
1587
1588 snd-virmidi= [HW,ALSA]
1589
1590 snd-wavefront= [HW,ALSA]
1591
1592 snd-ymfpci= [HW,ALSA]
a9913044 1593
1da177e4
LT
1594 sonicvibes= [HW,OSS]
1595 Format: <reverb>
a9913044 1596
1da177e4
LT
1597 sonycd535= [HW,CD]
1598 Format: <io>[,<irq>]
1599
1600 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1601 See Documentation/sonypi.txt
1602
1603 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1604 See Documentation/specialix.txt.
1605
1606 spia_io_base= [HW,MTD]
1607 spia_fio_base=
1608 spia_pedr=
1609 spia_peddr=
1610
1611 sscape= [HW,OSS]
1612 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1613
1da177e4
LT
1614 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1615 See Documentation/scsi/st.txt.
1616
1617 st0x= [HW,SCSI]
1618 See header of drivers/scsi/seagate.c.
1619
1620 sti= [PARISC,HW]
1621 Format: <num>
1622 Set the STI (builtin display/keyboard on the HP-PARISC
1623 machines) console (graphic card) which should be used
1624 as the initial boot-console.
1625 See also comment in drivers/video/console/sticore.c.
1626
1627 sti_font= [HW]
1628 See comment in drivers/video/console/sticore.c.
1629
1630 stifb= [HW]
1631 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1632
1da177e4 1633 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1634
1da177e4
LT
1635 switches= [HW,M68k]
1636
1637 sym53c416= [HW,SCSI]
1638 See header of drivers/scsi/sym53c416.c.
1639
1640 t128= [HW,SCSI]
1641 See header of drivers/scsi/t128.c.
1642
1643 tdfx= [HW,DRM]
1644
1645 thash_entries= [KNL,NET]
1646 Set number of hash buckets for TCP connection
1647
1648 time Show timing data prefixed to each printk message line
1649
734efb46
JS
1650 clocksource= [GENERIC_TIME] Override the default clocksource
1651 Override the default clocksource and use the clocksource
1652 with the name specified.
1653
1da177e4
LT
1654 tipar.timeout= [HW,PPT]
1655 Set communications timeout in tenths of a second
1656 (default 15).
1657
1658 tipar.delay= [HW,PPT]
1659 Set inter-bit delay in microseconds (default 10).
1660
1661 tmc8xx= [HW,SCSI]
1662 See header of drivers/scsi/seagate.c.
1663
1664 tmscsim= [HW,SCSI]
1665 See comment before function dc390_setup() in
1666 drivers/scsi/tmscsim.c.
1667
1668 tp720= [HW,PS2]
1669
1670 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1671 Format:
1672 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1673
1da177e4
LT
1674 tsdev.xres= [TS] Horizontal screen resolution.
1675 tsdev.yres= [TS] Vertical screen resolution.
1676
a9913044
RD
1677 turbografx.map[2|3]= [HW,JOY]
1678 TurboGraFX parallel port interface
1679 Format:
1680 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1681 See also Documentation/input/joystick-parport.txt
1682
1683 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1684 See header of drivers/scsi/u14-34f.c.
1685
1686 uart401= [HW,OSS]
1687 Format: <io>,<irq>
1688
1689 uart6850= [HW,OSS]
1690 Format: <io>,<irq>
1691
1da177e4
LT
1692 usbhid.mousepoll=
1693 [USBHID] The interval which mice are to be polled at.
a9913044 1694
e6e5494c
IM
1695 vdso= [IA-32]
1696 vdso=1: enable VDSO (default)
1697 vdso=0: disable VDSO mapping
1698
1da177e4
LT
1699 video= [FB] Frame buffer configuration
1700 See Documentation/fb/modedb.txt.
1701
1702 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1703 See Documentation/i386/boot.txt and
1704 Documentation/svga.txt.
1da177e4
LT
1705 Use vga=ask for menu.
1706 This is actually a boot loader parameter; the value is
1707 passed to the kernel using a special protocol.
1708
a9913044 1709 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1710 size of <nn>. This can be used to increase the
1711 minimum size (128MB on x86). It can also be used to
1712 decrease the size and leave more room for directly
1713 mapped kernel RAM.
1714
585c3047
PO
1715 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1716 Format: <command>
1da177e4 1717
585c3047
PO
1718 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1719 Format: <command>
1720
1721 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1722 Format: <command>
a9913044 1723
1da177e4
LT
1724 waveartist= [HW,OSS]
1725 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1726
1da177e4
LT
1727 wd33c93= [HW,SCSI]
1728 See header of drivers/scsi/wd33c93.c.
1729
1730 wd7000= [HW,SCSI]
1731 See header of drivers/scsi/wd7000.c.
1732
1733 wdt= [WDT] Watchdog
1734 See Documentation/watchdog/watchdog.txt.
1735
1736 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1737 xd_geo= See header of drivers/block/xd.c.
1738
1739 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1740 Format:
1741 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1742
a62eaf15
AK
1743 norandmaps Don't use address space randomization
1744 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1745
1da177e4 1746
a9913044 1747______________________________________________________________________
1da177e4
LT
1748
1749TODO:
1750
1751 Add documentation for ALSA options.
1752 Add more DRM drivers.