Merge branch 'misc' into test
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / kernel-parameters.txt
CommitLineData
e53dd083
MCC
1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
1da177e4
LT
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.
c99c108a 33 AGP AGP (Accelerated Graphics Port) is enabled.
1da177e4
LT
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
e7ba176b 37 AVR32 AVR32 architecture is enabled.
1da177e4 38 AX25 Appropriate AX.25 support is enabled.
0ae53640 39 BLACKFIN Blackfin architecture is enabled.
a9913044 40 DRM Direct Rendering Management support is enabled.
1da177e4
LT
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
1da177e4
LT
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
1da177e4
LT
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
11ef697b 52 LIBATA Libata driver is enabled
1da177e4
LT
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
309e57df 61 MSI Message Signaled Interrupts (PCI).
c8facbb6 62 MTD MTD (Memory Technology Device) support is enabled.
1da177e4
LT
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
734efb46 65 GENERIC_TIME The generic timeofday code is enabled.
1da177e4
LT
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
c8facbb6
RD
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
1da177e4
LT
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
7f785763 72 PCIE PCI Express support is enabled.
1da177e4
LT
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
20510f2f 79 ROOTPLUG The example Root Plug LSM is enabled.
1da177e4
LT
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
20510f2f 84 SECURITY Different security models are enabled.
1da177e4
LT
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
e523d93c 87 SH SuperH architecture is enabled.
1da177e4
LT
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
77437fd4
DB
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
1da177e4
LT
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 100 X86-32 X86-32, aka i386 architecture is enabled.
1da177e4
LT
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
104
105In addition, the following text indicates that the option:
106
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
110
111Parameters denoted with BOOT are actually interpreted by the boot
112loader, and have no meaning to the kernel directly.
113Do not modify the syntax of boot loader parameters without extreme
114need or coordination with <Documentation/i386/boot.txt>.
115
5558870b
KW
116There are also arch-specific kernel-parameters not documented here.
117See for example <Documentation/x86_64/boot-options.txt>.
118
1da177e4
LT
119Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120a trailing = on the name of any parameter states that that parameter will
121be entered as an environment variable, whereas its absence indicates that
122it will appear as a kernel argument readable via /proc/cmdline by programs
123running once the system is up.
124
9c4751fd 125The number of kernel parameters is not limited, but the length of the
126complete command line (parameters including spaces etc.) is limited to
127a fixed number of characters. This limit depends on the architecture
128and is between 256 and 4096 characters. It is defined in the file
129./include/asm/setup.h as COMMAND_LINE_SIZE.
130
131
03d926f8
BW
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
a9913044 134 Format: { force | off | ht | strict | noirq }
1da177e4
LT
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
a9913044 139 strict -- Be less tolerant of platforms that are not
1da177e4
LT
140 strictly ACPI specification compliant.
141
53471121 142 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 143
a1fdcc0d
LB
144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
4e381a4f 148 default: 0
a1fdcc0d 149
1da177e4 150 acpi_sleep= [HW,ACPI] Sleep options
bdfe6b7c 151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
23b168d4
PM
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
bdfe6b7c
SL
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
d8f3de0d
RW
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
160 used by default).
a9913044 161
1da177e4 162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 163 Format: { level | edge | high | low }
1da177e4 164
a9913044
RD
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
167 default in APIC mode
1da177e4 168
a9913044
RD
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
171 default in PIC mode
1da177e4 172
a9913044
RD
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
174 use by PCI
1da177e4
LT
175 Format: <irq>,<irq>...
176
a9913044 177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
1da177e4
LT
178 Format: <irq>,<irq>...
179
67effe8f
LB
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
181
a1f9e65e
LB
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
184
ae00d812
LB
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
1da177e4
LT
189
190 acpi_serialize [HW,ACPI] force serialization of AML methods
191
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
fa18f477
AK
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
198 HPET
1da177e4 199
f989106c 200 acpi.debug_layer= [HW,ACPI]
1da177e4 201 Format: <int>
a9913044 202 Each bit of the <int> indicates an ACPI debug layer,
1da177e4
LT
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
f989106c
ZR
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
216
217 acpi.debug_level= [HW,ACPI]
1da177e4 218 Format: <int>
a9913044 219 Each bit of the <int> indicates an ACPI debug level,
36eec5e2
TR
220 which corresponds to the level in an ACPI_DEBUG_PRINT
221 statement. After system has booted up, this mask
222 can be set via /sys/module/acpi/parameters/debug_level.
223
224 CONFIG_ACPI_DEBUG must be enabled for this to produce
225 any output. The number can be in decimal or prefixed
226 with 0x in hex. Some of these options produce so much
227 output that the system is unusable.
228
229 The following global components are defined by the
230 ACPI CA:
231 0x01 error
232 0x02 warn
233 0x04 init
234 0x08 debug object
235 0x10 info
236 0x20 init names
237 0x40 parse
238 0x80 load
239 0x100 dispatch
240 0x200 execute
241 0x400 names
242 0x800 operation region
243 0x1000 bfield
244 0x2000 tables
245 0x4000 values
246 0x8000 objects
247 0x10000 resources
248 0x20000 user requests
249 0x40000 package
250 The number can be in decimal or prefixed with 0x in hex.
251 Warning: Many of these options can produce a lot of
252 output and make your system unusable. Be very careful.
f989106c 253
f5adfaa3
ZY
254 acpi.power_nocheck= [HW,ACPI]
255 Format: 1/0 enable/disable the check of power state.
256 On some bogus BIOS the _PSC object/_STA object of
257 power resource can't return the correct device power
258 state. In such case it is unneccessary to check its
259 power state again in power transition.
260 1 : disable the power state check
261
cd4f0ef7 262 acpi_pm_good [X86-32,X86-64]
5d0cf410
JS
263 Override the pmtimer bug detection: force the kernel
264 to assume that this machine's pmtimer latches its value
265 and always returns good values.
266
c99c108a
CE
267 agp= [AGP]
268 { off | try_unsupported }
269 off: disable AGP support
270 try_unsupported: try to drive unsupported chipsets
271 (may crash computer or cause data corruption)
272
66759a01
CE
273 enable_timer_pin_1 [i386,x86-64]
274 Enable PIN 1 of APIC timer
a9913044
RD
275 Can be useful to work around chipset bugs
276 (in particular on some ATI chipsets).
66759a01
CE
277 The kernel tries to set a reasonable default.
278
279 disable_timer_pin_1 [i386,x86-64]
280 Disable PIN 1 of APIC timer
281 Can be useful to work around chipset bugs.
282
1da177e4
LT
283 ad1848= [HW,OSS]
284 Format: <io>,<irq>,<dma>,<dma2>,<type>
285
1da177e4
LT
286 advansys= [HW,SCSI]
287 See header of drivers/scsi/advansys.c.
288
289 advwdt= [HW,WDT] Advantech WDT
290 Format: <iostart>,<iostop>
291
292 aedsp16= [HW,OSS] Audio Excel DSP 16
293 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
294 See also header of sound/oss/aedsp16.c.
a9913044 295
1da177e4
LT
296 aha152x= [HW,SCSI]
297 See Documentation/scsi/aha152x.txt.
298
299 aha1542= [HW,SCSI]
300 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
301
302 aic7xxx= [HW,SCSI]
303 See Documentation/scsi/aic7xxx.txt.
304
305 aic79xx= [HW,SCSI]
306 See Documentation/scsi/aic79xx.txt.
307
54b4cbd2
JR
308 amd_iommu= [HW,X86-84]
309 Pass parameters to the AMD IOMMU driver in the system.
310 Possible values are:
54b4cbd2
JR
311 isolate - enable device isolation (each device, as far
312 as possible, will get its own protection
313 domain)
314 amd_iommu_size= [HW,X86-64]
315 Define the size of the aperture for the AMD IOMMU
316 driver. Possible values are:
317 '32M', '64M' (default), '128M', '256M', '512M', '1G'
318
1da177e4
LT
319 amijoy.map= [HW,JOY] Amiga joystick support
320 Map of devices attached to JOY0DAT and JOY1DAT
321 Format: <a>,<b>
322 See also Documentation/kernel/input/joystick.txt
323
324 analog.map= [HW,JOY] Analog joystick and gamepad support
325 Specifies type or capabilities of an analog joystick
326 connected to one of 16 gameports
327 Format: <type1>,<type2>,..<type16>
328
a9913044
RD
329 apc= [HW,SPARC]
330 Power management functions (SPARCstation-4/5 + deriv.)
1da177e4
LT
331 Format: noidle
332 Disable APC CPU standby support. SPARCstation-Fox does
333 not play well with APC CPU idle - disable it if you have
334 APC and your system crashes randomly.
335
c8facbb6
RD
336 apic= [APIC,i386] Advanced Programmable Interrupt Controller
337 Change the output verbosity whilst booting
1da177e4
LT
338 Format: { quiet (default) | verbose | debug }
339 Change the amount of debugging information output
340 when initialising the APIC and IO-APIC components.
a9913044 341
1da177e4 342 apm= [APM] Advanced Power Management
71f77055 343 See header of arch/x86/kernel/apm_32.c.
1da177e4 344
1da177e4
LT
345 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
346 Format: <io>,<irq>,<nodeID>
347
348 ataflop= [HW,M68k]
349
350 atarimouse= [HW,MOUSE] Atari Mouse
351
352 atascsi= [HW,SCSI] Atari SCSI
353
354 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
355 EzKey and similar keyboards
356
357 atkbd.reset= [HW] Reset keyboard during initialization
358
a9913044
RD
359 atkbd.set= [HW] Select keyboard code set
360 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
LT
361
362 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
363 keyboards
364
365 atkbd.softraw= [HW] Choose between synthetic and real raw mode
366 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
RD
367
368 atkbd.softrepeat= [HW]
369 Use software keyboard repeat
1da177e4
LT
370
371 autotest [IA64]
372
1da177e4
LT
373 baycom_epp= [HW,AX25]
374 Format: <io>,<mode>
a9913044 375
1da177e4
LT
376 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
377 Format: <io>,<mode>
378 See header of drivers/net/hamradio/baycom_par.c.
379
a9913044
RD
380 baycom_ser_fdx= [HW,AX25]
381 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
1da177e4
LT
382 Format: <io>,<irq>,<mode>[,<baud>]
383 See header of drivers/net/hamradio/baycom_ser_fdx.c.
384
a9913044
RD
385 baycom_ser_hdx= [HW,AX25]
386 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
1da177e4
LT
387 Format: <io>,<irq>,<mode>
388 See header of drivers/net/hamradio/baycom_ser_hdx.c.
389
bfe8df3d
RD
390 boot_delay= Milliseconds to delay each printk during boot.
391 Values larger than 10 seconds (10000) are changed to
392 no delay (0).
393 Format: integer
394
35fc908d
AH
395 bootmem_debug [KNL] Enable bootmem allocator debug messages.
396
1da177e4 397 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
a9913044
RD
398 bttv.radio= Most important insmod options are available as
399 kernel args too.
1da177e4
LT
400 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
401 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
402
403 BusLogic= [HW,SCSI]
404 See drivers/scsi/BusLogic.c, comment before function
405 BusLogic_ParseDriverOptions().
406
407 c101= [NET] Moxa C101 synchronous serial card
408
cd4f0ef7 409 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
1da177e4
LT
410 Sometimes CPU hardware bugs make them report the cache
411 size incorrectly. The kernel will attempt work arounds
412 to fix known problems, but for some CPUs it is not
413 possible to determine what the correct size should be.
414 This option provides an override for these situations.
415
076c54c5
AD
416 security= [SECURITY] Choose a security module to enable at boot.
417 If this boot parameter is not specified, only the first
418 security module asking for security registration will be
419 loaded. An invalid security module name will be treated
420 as if no module has been chosen.
421
20510f2f
JM
422 capability.disable=
423 [SECURITY] Disable capabilities. This would normally
424 be used only if an alternative security model is to be
425 configured. Potentially dangerous and should only be
426 used if you are entirely sure of the consequences.
427
14ff56bb
SO
428 ccw_timeout_log [S390]
429 See Documentation/s390/CommonIO for details.
1da177e4 430
8bab8dde
PM
431 cgroup_disable= [KNL] Disable a particular controller
432 Format: {name of the controller(s) to disable}
433 {Currently supported controllers - "memory"}
434
1da177e4
LT
435 checkreqprot [SELINUX] Set initial checkreqprot flag value.
436 Format: { "0" | "1" }
437 See security/selinux/Kconfig help text.
a9913044
RD
438 0 -- check protection applied by kernel (includes
439 any implied execute protection).
1da177e4
LT
440 1 -- check protection requested by application.
441 Default value is set via a kernel config option.
a9913044
RD
442 Value can be changed at runtime via
443 /selinux/checkreqprot.
444
661ca0da
SO
445 cio_ignore= [S390]
446 See Documentation/s390/CommonIO for details.
447
cd4f0ef7 448 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 449 [Deprecated]
3f6dee9b 450 Forces specified clocksource (if available) to be used
734efb46 451 when calculating gettimeofday(). If specified
3f6dee9b 452 clocksource is not available, it defaults to PIT.
1da177e4
LT
453 Format: { pit | tsc | cyclone | pmtmr }
454
3d6ac984
RD
455 clocksource= [GENERIC_TIME] Override the default clocksource
456 Format: <string>
457 Override the default clocksource and use the clocksource
458 with the name specified.
459 Some clocksource names to choose from, depending on
460 the platform:
461 [all] jiffies (this is the base, fallback clocksource)
462 [ACPI] acpi_pm
463 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
464 pxa_timer,timer3,32k_counter,timer0_1
465 [AVR32] avr32
cd4f0ef7 466 [X86-32] pit,hpet,tsc,vmi-timer;
3d6ac984
RD
467 scx200_hrt on Geode; cyclone on IBM x440
468 [MIPS] MIPS
469 [PARISC] cr16
470 [S390] tod
471 [SH] SuperH
472 [SPARC64] tick
473 [X86-64] hpet,tsc
474
ac72e788
AK
475 clearcpuid=BITNUM [X86]
476 Disable CPUID feature X for the kernel. See
477 include/asm-x86/cpufeature.h for the valid bit numbers.
478 Note the Linux specific bits are not necessarily
479 stable over kernel options, but the vendor specific
480 ones should be.
481 Also note that user programs calling CPUID directly
482 or using the feature without checking anything
483 will still see it. This just prevents it from
484 being used by the kernel or shown in /proc/cpuinfo.
485 Also note the kernel might malfunction if you disable
486 some critical bits.
487
a25bd949
AV
488 code_bytes [IA32/X86_64] How many bytes of object code to print
489 in an oops report.
86c41837
CE
490 Range: 0 - 8192
491 Default: 64
492
f9262c12
AK
493 disable_8254_timer
494 enable_8254_timer
495 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
496 over the 8254 in addition to over the IO-APIC. The
497 kernel tries to set a sensible default.
498
b17530bd
TG
499 hpet= [X86-32,HPET] option to control HPET usage
500 Format: { enable (default) | disable | force }
501 disable: disable HPET and use PIT instead
d79a5f80
CC
502 force: allow force enabled of undocumented chips (ICH4,
503 VIA, nVidia)
1da177e4 504
1da177e4 505 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
506 Format:
507 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
508
509 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
510 Format: <io>[,<irq>]
511
a9913044
RD
512 com90xx= [HW,NET]
513 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
514 Format: <io>[,<irq>[,<memstart>]]
515
516 condev= [HW,S390] console device
517 conmode=
a9913044 518
1da177e4
LT
519 console= [KNL] Output console device and options.
520
521 tty<n> Use the virtual console device <n>.
522
523 ttyS<n>[,options]
f1a1c2dc 524 ttyUSB0[,options]
1da177e4 525 Use the specified serial port. The options are of
f1a1c2dc
RD
526 the form "bbbbpnf", where "bbbb" is the baud rate,
527 "p" is parity ("n", "o", or "e"), "n" is number of
528 bits, and "f" is flow control ("r" for RTS or
529 omit it). Default is "9600n8".
530
531 See Documentation/serial-console.txt for more
532 information. See
533 Documentation/networking/netconsole.txt for an
534 alternative.
1da177e4 535
18a8bd94
YL
536 uart[8250],io,<addr>[,options]
537 uart[8250],mmio,<addr>[,options]
1da177e4
LT
538 Start an early, polled-mode console on the 8250/16550
539 UART at the specified I/O port or MMIO address,
540 switching to the matching ttyS device later. The
541 options are the same as for ttyS, above.
542
f7511d5f
ST
543 If the device connected to the port is not a TTY but a braille
544 device, prepend "brl," before the device type, for instance
545 console=brl,ttyS0
546 For now, only VisioBraille is supported.
547
18a8bd94
YL
548 earlycon= [KNL] Output early console device and options.
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address.
553 The options are the same as for ttyS, above.
554
8f4ce8c3
AS
555 no_console_suspend
556 [HW] Never suspend the console
557 Disable suspending of consoles during suspend and
558 hibernate operations. Once disabled, debugging
559 messages can reach various consoles while the rest
560 of the system is being put to sleep (ie, while
561 debugging driver suspend/resume hooks). This may
562 not work reliably with all consoles, but is known
563 to work with serial and VGA consoles.
564
1da177e4 565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
566 Format:
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 568
dc009d92
EB
569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
572
fb391599
BW
573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
579
1da177e4
LT
580 cs4232= [HW,OSS]
581 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
582
583 cs89x0_dma= [HW,NET]
584 Format: <dma>
585
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
a9913044 588
a9913044 589 dasd= [HW,NET]
1da177e4
LT
590 See header of drivers/s390/block/dasd_devmap.c.
591
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
596
597 debug [KNL] Enable kernel debugging (events log level).
598
cae2ed9a
IM
599 debug_locks_verbose=
600 [KNL] verbose self-tests
601 Format=<0|1>
602 Print debugging info while doing the locking API
603 self-tests.
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
607
3ac7fe5a
TG
608 debug_objects [KNL] Enable object debugging
609
d3af01f1
TG
610 debugpat [X86] Enable PAT debugging
611
2d27a966 612 decnet.addr= [HW,NET]
1da177e4
LT
613 Format: <area>[,<node>]
614 See also Documentation/networking/decnet.txt.
615
ecb77fa9 616 vt.default_blu= [VT]
55ff9780
AD
617 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
618 Change the default blue palette of the console.
619 This is a 16-member array composed of values
620 ranging from 0-255.
621
ecb77fa9 622 vt.default_grn= [VT]
55ff9780
AD
623 Format: <green0>,<green1>,<green2>,...,<green15>
624 Change the default green palette of the console.
625 This is a 16-member array composed of values
626 ranging from 0-255.
627
ecb77fa9 628 vt.default_red= [VT]
55ff9780
AD
629 Format: <red0>,<red1>,<red2>,...,<red15>
630 Change the default red palette of the console.
631 This is a 16-member array composed of values
632 ranging from 0-255.
633
ecb77fa9
ST
634 vt.default_utf8=
635 [VT]
55ff9780
AD
636 Format=<0|1>
637 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
638 Default is 1, i.e. UTF-8 mode is enabled for all
639 newly opened terminals.
55ff9780 640
1da177e4
LT
641 dhash_entries= [KNL]
642 Set number of hash buckets for dentry cache.
a9913044 643
1da177e4
LT
644 digi= [HW,SERIAL]
645 IO parameters + enable/disable command.
646
647 digiepca= [HW,SERIAL]
648 See drivers/char/README.epca and
649 Documentation/digiepca.txt.
650
95ffa243
YL
651 disable_mtrr_cleanup [X86]
652 enable_mtrr_cleanup [X86]
653 The kernel tries to adjust MTRR layout from continuous
654 to discrete, to make X server driver able to add WB
655 entry later. This parameter enables/disables that.
656
657 mtrr_chunk_size=nn[KMG] [X86]
658 used for mtrr cleanup. It is largest continous chunk
659 that could hold holes aka. UC entries.
660
661 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
662 Used for mtrr cleanup. It is granularity of mtrr block.
663 Default is 1.
664 Large value could prevent small alignment from
665 using up MTRRs.
666
667 mtrr_spare_reg_nr=n [X86]
668 Format: <integer>
669 Range: 0,7 : spare reg number
670 Default : 1
671 Used for mtrr cleanup. It is spare mtrr entries number.
672 Set to 2 or more if your graphical card needs more.
95ffa243 673
093af8d7 674 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
675 By default the kernel will trim any uncacheable
676 memory out of your available memory pool based on
677 MTRR settings. This parameter disables that behavior,
678 possibly causing your machine to run very slowly.
679
1da177e4
LT
680 dmasound= [HW,OSS] Sound subsystem buffers
681
682 dscc4.setup= [NET]
683
684 dtc3181e= [HW,SCSI]
685
0ae53640 686 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
687 earlyprintk=vga
688 earlyprintk=serial[,ttySn[,baudrate]]
689
a9913044 690 Append ",keep" to not disable it when the real console
1da177e4
LT
691 takes over.
692
693 Only vga or serial at a time, not both.
694
695 Currently only ttyS0 and ttyS1 are supported.
696
697 Interaction with the standard serial driver is not
698 very good.
699
700 The VGA output is eventually overwritten by the real
701 console.
702
703 eata= [HW,SCSI]
704
1da177e4 705 edd= [EDD]
8c4dd606 706 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 707
1da177e4
LT
708 eisa_irq_edge= [PARISC,HW]
709 See header of drivers/parisc/eisa.c.
710
cd4f0ef7 711 elanfreq= [X86-32]
1da177e4 712 See comment before function elanfreq_setup() in
71f77055 713 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
714
715 elevator= [IOSCHED]
16ab3adf 716 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
717 See Documentation/block/as-iosched.txt and
718 Documentation/block/deadline-iosched.txt for details.
719
cd4f0ef7 720 elfcorehdr= [X86-32, X86_64]
a9913044 721 Specifies physical address of start of kernel core
aac04b32
VG
722 image elf header. Generally kexec loader will
723 pass this option to capture kernel.
724 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
725
726 enforcing [SELINUX] Set initial enforcing status.
727 Format: {"0" | "1"}
728 See security/selinux/Kconfig help text.
729 0 -- permissive (log only, no denials).
730 1 -- enforcing (deny and log).
731 Default value is 0.
732 Value can be changed at runtime via /selinux/enforce.
733
1da177e4
LT
734 es1371= [HW,OSS]
735 Format: <spdif>,[<nomix>,[<amplifier>]]
736 See also header of sound/oss/es1371.c.
a9913044 737
1da177e4
LT
738 ether= [HW,NET] Ethernet cards parameters
739 This option is obsoleted by the "netdev=" option, which
740 has equivalent usage. See its documentation for details.
741
742 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
743 Format: <io>[,<irq>]
744
de1ba09b
AM
745 failslab=
746 fail_page_alloc=
747 fail_make_request=[KNL]
748 General fault injection mechanism.
749 Format: <interval>,<probability>,<space>,<times>
750 See also /Documentation/fault-injection/.
751
1da177e4
LT
752 fd_mcs= [HW,SCSI]
753 See header of drivers/scsi/fd_mcs.c.
754
755 fdomain= [HW,SCSI]
756 See header of drivers/scsi/fdomain.c.
757
758 floppy= [HW]
759 See Documentation/floppy.txt.
760
f13ae30e
AC
761 force_pal_cache_flush
762 [IA-64] Avoid check_sal_cache_flush which may hang on
763 buggy SAL_CACHE_FLUSH implementations. Using this
764 parameter will force ia64_sal_cache_flush to call
765 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
766
1da177e4
LT
767 gamecon.map[2|3]=
768 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
769 support via parallel port (up to 5 devices per port)
770 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
771 See also Documentation/input/joystick-parport.txt
772
773 gamma= [HW,DRM]
774
aaf23042
YL
775 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
776 Format: off | on
777 default: on
778
1da177e4
LT
779 gdth= [HW,SCSI]
780 See header of drivers/scsi/gdth.c.
781
782 gpt [EFI] Forces disk with valid GPT signature but
783 invalid Protective MBR to be treated as GPT.
784
1da177e4
LT
785 gvp11= [HW,SCSI]
786
787 hashdist= [KNL,NUMA] Large hashes allocated during boot
788 are distributed across NUMA nodes. Defaults on
789 for IA-64, off otherwise.
a9913044 790 Format: 0 | 1 (for off | on)
1da177e4
LT
791
792 hcl= [IA-64] SGI's Hardware Graph compatibility layer
793
794 hd= [EIDE] (E)IDE hard drive subsystem geometry
795 Format: <cyl>,<head>,<sect>
796
1da177e4
LT
797 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
798 size of <nn>. This works even on boxes that have no
799 highmem otherwise. This also works to reduce highmem
800 size on bigger boxes.
801
54cdfdb4
TG
802 highres= [KNL] Enable/disable high resolution timer mode.
803 Valid parameters: "on", "off"
804 Default: "on"
805
1da177e4
LT
806 hisax= [HW,ISDN]
807 See Documentation/isdn/README.HiSax.
808
b4718e62
AK
809 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
810 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
811 On x86-64 and powerpc, this option can be specified
812 multiple times interleaved with hugepages= to reserve
813 huge pages of different sizes. Valid pages sizes on
814 x86-64 are 2M (when the CPU supports "pse") and 1G
815 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
816 Note that 1GB pages can only be allocated at boot time
817 using hugepages= and not freed afterwards.
e11bfbfc
NP
818 default_hugepagesz=
819 [same as hugepagesz=] The size of the default
820 HugeTLB page size. This is the size represented by
821 the legacy /proc/ hugepages APIs, used for SHM, and
822 default size when mounting hugetlbfs filesystems.
823 Defaults to the default architecture's huge page size
824 if not specified.
1da177e4 825
1da177e4 826 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
827 i8042.dumbkbd [HW] Pretend that controller can only read data from
828 keyboard and cannot control its state
1da177e4
LT
829 (Don't attempt to blink the leds)
830 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 831 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
832 i8042.noloop [HW] Disable the AUX Loopback command while probing
833 for the AUX port
1da177e4
LT
834 i8042.nomux [HW] Don't check presence of an active multiplexing
835 controller
836 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
837 controllers
838 i8042.panicblink=
839 [HW] Frequency with which keyboard LEDs should blink
840 when kernel panics (default is 0.5 sec)
841 i8042.reset [HW] Reset the controller during init and cleanup
842 i8042.unlock [HW] Unlock (ignore) the keylock
843
844 i810= [HW,DRM]
845
e70c9d5e
DT
846 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
847 indicates that the driver is running on unsupported
848 hardware.
1da177e4
LT
849 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
850 does not match list of supported models.
851 i8k.power_status
852 [HW] Report power status in /proc/i8k
853 (disabled by default)
854 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
855 capability is set.
856
857 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
858 See Documentation/mca.txt.
859
860 icn= [HW,ISDN]
861 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
862
863 ide= [HW] (E)IDE subsystem
a594eeb1 864 Format: ide=nodma or ide=doubler
1c10e938 865 See Documentation/ide/ide.txt.
1da177e4 866
1da177e4 867 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 868 See Documentation/ide/ide.txt.
1da177e4 869
f039b754 870 idle= [X86]
da5e09a1 871 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
872 Poll forces a polling idle loop that can slightly improves the performance
873 of waking up a idle CPU, but will use a lot of power and make the system
874 run hot. Not recommended.
875 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
876 to not use it because it doesn't save as much power as a normal idle
877 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
878 as idle=poll.
c1e3b377
ZY
879 idle=halt. Halt is forced to be used for CPU idle.
880 In such case C2/C3 won't be used again.
da5e09a1 881 idle=nomwait. Disable mwait for CPU C-states
a9913044 882
594765a7
DC
883 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
884 Claim all unknown PCI IDE storage controllers.
885
79290822
IM
886 ignore_loglevel [KNL]
887 Ignore loglevel setting - this will print /all/
888 kernel messages to the console. Useful for debugging.
889
1da177e4
LT
890 ihash_entries= [KNL]
891 Set number of hash buckets for inode cache.
892
893 in2000= [HW,SCSI]
894 See header of drivers/scsi/in2000.c.
895
896 init= [KNL]
897 Format: <full_path>
898 Run specified binary instead of /sbin/init as init
899 process.
900
901 initcall_debug [KNL] Trace initcalls as they are executed. Useful
902 for working out where the kernel is dying during
903 startup.
904
905 initrd= [BOOT] Specify the location of the initial ramdisk
906
907 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
908 Format: <irq>
909
910 inttest= [IA64]
911
b552da87
PM
912 iommu= [x86]
913 off
914 force
915 noforce
916 biomerge
917 panic
918 nopanic
919 merge
920 nomerge
921 forcesac
922 soft
923
924
ba395927
KA
925 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
926 off
927 Disable intel iommu driver.
928 igfx_off [Default Off]
929 By default, gfx is mapped as normal device. If a gfx
930 device has a dedicated DMAR unit, the DMAR unit is
931 bypassed by not enabling DMAR with this option. In
932 this case, gfx device will use physical address for
933 DMA.
7d3b03ce
KA
934 forcedac [x86_64]
935 With this option iommu will not optimize to look
936 for io virtual address below 32 bit forcing dual
937 address cycle on pci bus for cards supporting greater
938 than 32 bit addressing. The default is to look
939 for translation below 32 bit and if not available
940 then look in the higher range.
5e0d2a6f 941 strict [Default Off]
942 With this option on every unmap_single operation will
943 result in a hardware IOTLB flush operation as opposed
944 to batching them for performance.
ba395927 945
b02aae9c 946 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
947 0x80
948 Standard port 0x80 based delay
949 0xed
950 Alternate port 0xed based delay (needed on some systems)
b02aae9c 951 udelay
6e7c4025
IM
952 Simple two microseconds delay
953 none
954 No delay
b02aae9c 955
1da177e4
LT
956 io7= [HW] IO7 for Marvel based alpha systems
957 See comment before marvel_specify_io7 in
958 arch/alpha/kernel/core_marvel.c.
959
960 ip= [IP_PNP]
6ded55da 961 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
962
963 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
964 See comment before ip2_setup() in
965 drivers/char/ip2/ip2base.c.
1da177e4
LT
966
967 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
968 See header of drivers/scsi/ips.c.
969
72c4a13a
SH
970 ports= [IP_VS_FTP] IPVS ftp helper module
971 Default is 21.
972 Up to 8 (IP_VS_APP_MAX_PORTS) ports
973 may be specified.
974 Format: <port>,<port>....
975
200803df
AC
976 irqfixup [HW]
977 When an interrupt is not handled search all handlers
978 for it. Intended to get systems with badly broken
979 firmware running.
980
981 irqpoll [HW]
982 When an interrupt is not handled search all handlers
983 for it. Also check all handlers each timer
984 interrupt. Intended to get systems with badly broken
985 firmware running.
986
1da177e4 987 isapnp= [ISAPNP]
a9913044 988 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
989
990 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
991 Format:
992 <cpu number>,...,<cpu number>
993 or
994 <cpu number>-<cpu number> (must be a positive range in ascending order)
995 or a mixture
996 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
997 This option can be used to specify one or more CPUs
998 to isolate from the general SMP balancing and scheduling
999 algorithms. The only way to move a process onto or off
1000 an "isolated" CPU is via the CPU affinity syscalls.
1001 <cpu number> begins at 0 and the maximum value is
1002 "number of CPUs in system - 1".
1003
1004 This option is the preferred way to isolate CPUs. The
a9913044
RD
1005 alternative -- manually setting the CPU mask of all
1006 tasks in the system -- can cause problems and
1007 suboptimal load balancer performance.
1da177e4 1008
a9913044 1009 iucv= [HW,NET]
1da177e4
LT
1010
1011 js= [HW,JOY] Analog joystick
1012 See Documentation/input/joystick.txt.
1013
cd4f0ef7 1014 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
1015 specifies the amount of memory usable by the kernel
1016 for non-movable allocations. The requested amount is
1017 spread evenly throughout all nodes in the system. The
1018 remaining memory in each node is used for Movable
1019 pages. In the event, a node is too small to have both
1020 kernelcore and Movable pages, kernelcore pages will
1021 take priority and other nodes will have a larger number
1022 of kernelcore pages. The Movable zone is used for the
1023 allocation of pages that may be reclaimed or moved
1024 by the page migration subsystem. This means that
1025 HugeTLB pages may not be allocated from this zone.
1026 Note that allocations like PTEs-from-HighMem still
1027 use the HighMem zone if it exists, and the Normal
1028 zone if it does not.
1029
cd4f0ef7 1030 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1031 is similar to kernelcore except it specifies the
1032 amount of memory used for migratable allocations.
1033 If both kernelcore and movablecore is specified,
1034 then kernelcore will be at *least* the specified
1035 value but may be more. If movablecore on its own
1036 is specified, the administrator must be careful
1037 that the amount of memory usable for all allocations
1038 is not too small.
1039
1da177e4
LT
1040 keepinitrd [HW,ARM]
1041
cd4f0ef7 1042 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1043 in oops dumps.
1044
6cdf6e06
JW
1045 kgdboc= [HW] kgdb over consoles.
1046 Requires a tty driver that supports console polling.
1047 (only serial suported for now)
1048 Format: <serial_device>[,baud]
1049
1da177e4
LT
1050 l2cr= [PPC]
1051
a78bfbfc
RB
1052 l3cr= [PPC]
1053
cd4f0ef7 1054 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1055 disabled it.
1da177e4 1056
cd4f0ef7 1057 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1058 C2 power state.
1059
fcb71f6f
FC
1060 libata.dma= [LIBATA] DMA control
1061 libata.dma=0 Disable all PATA and SATA DMA
1062 libata.dma=1 PATA and SATA Disk DMA only
1063 libata.dma=2 ATAPI (CDROM) DMA only
1064 libata.dma=4 Compact Flash DMA only
1065 Combinations also work, so libata.dma=3 enables DMA
1066 for disks and CDROMs, but not CFs.
1067
78e70c23
DJ
1068 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1069 when set.
1070 Format: <int>
1071
33267325
TH
1072 libata.force= [LIBATA] Force configurations. The format is comma
1073 separated list of "[ID:]VAL" where ID is
1074 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1075 matching port, link or device. Basically, it matches
1076 the ATA ID string printed on console by libata. If
1077 the whole ID part is omitted, the last PORT and DEVICE
1078 values are used. If ID hasn't been specified yet, the
1079 configuration applies to all ports, links and devices.
1080
1081 If only DEVICE is omitted, the parameter applies to
1082 the port and all links and devices behind it. DEVICE
1083 number of 0 either selects the first device or the
1084 first fan-out link behind PMP device. It does not
1085 select the host link. DEVICE number of 15 selects the
1086 host link and device attached to it.
1087
1088 The VAL specifies the configuration to force. As long
1089 as there's no ambiguity shortcut notation is allowed.
1090 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1091 The following configurations can be forced.
1092
1093 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1094 Any ID with matching PORT is used.
1095
1096 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1097
1098 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1099 udma[/][16,25,33,44,66,100,133] notation is also
1100 allowed.
1101
1102 * [no]ncq: Turn on or off NCQ.
1103
05944bdf
TH
1104 * nohrst, nosrst, norst: suppress hard, soft
1105 and both resets.
1106
33267325
TH
1107 If there are multiple matching configurations changing
1108 the same attribute, the last one is used.
1109
1da177e4
LT
1110 load_ramdisk= [RAM] List of ramdisks to load from floppy
1111 See Documentation/ramdisk.txt.
1112
a6b25b67
RD
1113 lockd.nlm_grace_period=P [NFS] Assign grace period.
1114 Format: <integer>
1da177e4 1115
a6b25b67
RD
1116 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1117 Format: <integer>
1118
1119 lockd.nlm_timeout=T [NFS] Assign timeout value.
1120 Format: <integer>
1121
1122 lockd.nlm_udpport=M [NFS] Assign UDP port.
1123 Format: <integer>
1da177e4
LT
1124
1125 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1126 Format: <irq>
1127
1128 loglevel= All Kernel Messages with a loglevel smaller than the
1129 console loglevel will be printed to the console. It can
1130 also be changed with klogd or other programs. The
1131 loglevels are defined as follows:
1132
1133 0 (KERN_EMERG) system is unusable
1134 1 (KERN_ALERT) action must be taken immediately
1135 2 (KERN_CRIT) critical conditions
1136 3 (KERN_ERR) error conditions
1137 4 (KERN_WARNING) warning conditions
1138 5 (KERN_NOTICE) normal but significant condition
1139 6 (KERN_INFO) informational
1140 7 (KERN_DEBUG) debug-level messages
1141
1142 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1143 Format: { n | nk | nM }
1144 n must be a power of two. The default size
1145 is set in the kernel config file.
1da177e4 1146
accaa24c
RD
1147 logo.nologo [FB] Disables display of the built-in Linux logo.
1148 This may be used to provide more screen space for
1149 kernel log messages and is useful when debugging
1150 kernel boot problems.
1151
1da177e4
LT
1152 lp=0 [LP] Specify parallel ports to use, e.g,
1153 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1154 lp=reset first parallel port). 'lp=0' disables the
1155 lp=auto printer driver. 'lp=reset' (which can be
1156 specified in addition to the ports) causes
1157 attached printers to be reset. Using
1158 lp=port1,port2,... specifies the parallel ports
1159 to associate lp devices with, starting with
1160 lp0. A port specification may be 'none' to skip
1161 that lp device, or a parport name such as
1162 'parport0'. Specifying 'lp=auto' instead of a
1163 port specification list means that device IDs
1164 from each port should be examined, to see if
1165 an IEEE 1284-compliant printer is attached; if
1166 so, the driver will manage that printer.
1167 See also header of drivers/char/lp.c.
1168
1169 lpj=n [KNL]
1170 Sets loops_per_jiffy to given constant, thus avoiding
1171 time-consuming boot-time autodetection (up to 250 ms per
1172 CPU). 0 enables autodetection (default). To determine
1173 the correct value for your kernel, boot with normal
1174 autodetection and see what value is printed. Note that
1175 on SMP systems the preset will be applied to all CPUs,
1176 which is likely to cause problems if your CPUs need
1177 significantly divergent settings. An incorrect value
1178 will cause delays in the kernel to be wrong, leading to
1179 unpredictable I/O errors and other breakage. Although
1180 unlikely, in the extreme case this might damage your
1181 hardware.
1182
1183 ltpc= [NET]
1184 Format: <io>,<irq>,<dma>
1185
a9913044
RD
1186 mac5380= [HW,SCSI] Format:
1187 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1188
a9913044
RD
1189 machvec= [IA64] Force the use of a particular machine-vector
1190 (machvec) in a generic kernel.
1191 Example: machvec=hpzx1_swiotlb
1da177e4 1192
a9913044 1193 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1194 be mounted
1195 Format: <1-256>
1196
1197 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1198 should make use of. maxcpus=n : n >= 0 limits the
1199 kernel to using 'n' processors. n=0 is a special case,
1200 it is equivalent to "nosmp", which also disables
1201 the IO APIC.
1da177e4 1202
2b2c3750
BP
1203 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1204 equal to this physical address is ignored.
1205
a9913044 1206 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1207 Should be between 1 and 2^32-1.
1208
1209 max_report_luns=
a9913044 1210 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1211 Should be between 1 and 16384.
1212
1da177e4
LT
1213 mcatest= [IA-64]
1214
cd4f0ef7 1215 mce [X86-32] Machine Check Exception
1da177e4 1216
909dd324
AK
1217 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1218
1da177e4
LT
1219 md= [HW] RAID subsystems devices and level
1220 See Documentation/md.txt.
a9913044 1221
1da177e4
LT
1222 mdacon= [MDA]
1223 Format: <first>,<last>
1224 Specifies range of consoles to be captured by the MDA.
a9913044 1225
1da177e4
LT
1226 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1227 Amount of memory to be used when the kernel is not able
1228 to see the whole system memory or for test.
cd4f0ef7 1229 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1230 address space collisions. Without memmap= PCI devices
1231 could be placed at addresses belonging to unused RAM.
1232
cd4f0ef7 1233 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1234 memory.
1235
cd4f0ef7 1236 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1237 E820 memory map, as specified by the user.
1238 Such memmap=exactmap lines can be constructed based on
1239 BIOS output or other requirements. See the memmap=nn@ss
1240 option description.
1241
1242 memmap=nn[KMG]@ss[KMG]
1243 [KNL] Force usage of a specific region of memory
1244 Region of memory to be used, from ss to ss+nn.
1245
1246 memmap=nn[KMG]#ss[KMG]
1247 [KNL,ACPI] Mark specific memory as ACPI data.
1248 Region of memory to be used, from ss to ss+nn.
1249
1250 memmap=nn[KMG]$ss[KMG]
1251 [KNL,ACPI] Mark specific memory as reserved.
1252 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1253 Example: Exclude memory from 0x18690000-0x1869ffff
1254 memmap=64K$0x18690000
1255 or
1256 memmap=0x10000$0x18690000
1da177e4 1257
caadbdce 1258 memtest= [KNL,X86] Enable memtest
c64df707
YL
1259 Format: <integer>
1260 range: 0,4 : pattern number
1261 default : 0 <disable>
1262
1da177e4
LT
1263 meye.*= [HW] Set MotionEye Camera parameters
1264 See Documentation/video4linux/meye.txt.
1265
8f36881b
AS
1266 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1267 Multi-Function General Purpose Timers on AMD Geode
1268 platforms.
1269
e6c4dc6c
WT
1270 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1271 the BIOS has incorrectly applied a workaround. TinyBIOS
1272 version 0.98 is known to be affected, 0.99 fixes the
1273 problem by letting the user disable the workaround.
1274
1da177e4
LT
1275 mga= [HW,DRM]
1276
6b74ab97
MG
1277 mminit_loglevel=
1278 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1279 parameter allows control of the logging verbosity for
1280 the additional memory initialisation checks. A value
1281 of 0 disables mminit logging and a level of 4 will
1282 log everything. Information is printed at KERN_DEBUG
1283 so loglevel=8 may also need to be specified.
1284
1da177e4
LT
1285 mousedev.tap_time=
1286 [MOUSE] Maximum time between finger touching and
1287 leaving touchpad surface for touch to be considered
1288 a tap and be reported as a left button click (for
1289 touchpads working in absolute mode only).
1290 Format: <msecs>
1291 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1292 reporting absolute coordinates, such as tablets
1293 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1294 reporting absolute coordinates, such as tablets
1295
1296 mpu401= [HW,OSS]
1297 Format: <io>,<irq>
1298
1299 MTD_Partition= [MTD]
1300 Format: <name>,<region-number>,<size>,<offset>
1301
a9913044
RD
1302 MTD_Region= [MTD] Format:
1303 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1304
1305 mtdparts= [MTD]
c8facbb6 1306 See drivers/mtd/cmdlinepart.c.
1da177e4 1307
9db829f4
BD
1308 mtdset= [ARM]
1309 ARM/S3C2412 JIVE boot control
1310
1311 See arch/arm/mach-s3c2412/mach-jive.c
1312
1da177e4 1313 mtouchusb.raw_coordinates=
a9913044
RD
1314 [HW] Make the MicroTouch USB driver use raw coordinates
1315 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1316
1317 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1318
1319 NCR_D700= [HW,SCSI]
1320 See header of drivers/scsi/NCR_D700.c.
1321
1322 ncr5380= [HW,SCSI]
1323
1324 ncr53c400= [HW,SCSI]
1325
1326 ncr53c400a= [HW,SCSI]
1327
1328 ncr53c406a= [HW,SCSI]
1329
1330 ncr53c8xx= [HW,SCSI]
1331
1332 netdev= [NET] Network devices parameters
1333 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1334 Note that mem_start is often overloaded to mean
1335 something different and driver-specific.
a9913044
RD
1336 This usage is only documented in each driver source
1337 file if at all.
1338
58401572
KPO
1339 nf_conntrack.acct=
1340 [NETFILTER] Enable connection tracking flow accounting
1341 0 to disable accounting
1342 1 to enable accounting
1343 Default value depends on CONFIG_NF_CT_ACCT that is
1344 going to be removed in 2.6.29.
1345
1da177e4 1346 nfsaddrs= [NFS]
6ded55da 1347 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1348
1349 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1350 See Documentation/filesystems/nfsroot.txt.
1da177e4 1351
a72b4422
TM
1352 nfs.callback_tcpport=
1353 [NFS] set the TCP port on which the NFSv4 callback
1354 channel should listen.
1355
58df095b
TM
1356 nfs.idmap_cache_timeout=
1357 [NFS] set the maximum lifetime for idmapper cache
1358 entries.
1359
f43bf0be
TM
1360 nfs.enable_ino64=
1361 [NFS] enable 64-bit inode numbers.
1362 If zero, the NFS client will fake up a 32-bit inode
1363 number for the readdir() and stat() syscalls instead
1364 of returning the full 64-bit number.
1365 The default is to return 64-bit inode numbers.
1366
e7ba176b
HS
1367 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1368 when a NMI is triggered.
1369 Format: [state][,regs][,debounce][,die]
1370
cd4f0ef7 1371 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1372
cd4f0ef7 1373 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1374 emulation library even if a 387 maths coprocessor
1375 is present.
1376
c1aee215
CL
1377 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1378 caches in the slab allocator. Saves per-node memory,
1379 but will impact performance.
3395ee05 1380
a9913044
RD
1381 noalign [KNL,ARM]
1382
1da177e4
LT
1383 noapic [SMP,APIC] Tells the kernel to not make use of any
1384 IOAPICs that may be present in the system.
1385
1da177e4
LT
1386 nobats [PPC] Do not use BATs for mapping kernel lowmem
1387 on "Classic" PPC cores.
1388
1389 nocache [ARM]
a9913044 1390
163ecdff
SN
1391 nodelayacct [KNL] Disable per-task delay accounting
1392
1da177e4
LT
1393 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1394
8b2cb7a8
HY
1395 noefi [X86-32,X86-64] Disable EFI runtime services support.
1396
1da177e4
LT
1397 noexec [IA-64]
1398
cd4f0ef7 1399 noexec [X86-32,X86-64]
f5a1b191 1400 On X86-32 available only on PAE configured kernels.
1da177e4 1401 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1402 noexec=off: disable non-executable mappings
1403
1404 noexec32 [X86-64]
1405 This affects only 32-bit executables.
1406 noexec32=on: enable non-executable mappings (default)
1407 read doesn't imply executable mappings
1408 noexec32=off: disable non-executable mappings
1409 read implies executable mappings
1da177e4 1410
cd4f0ef7 1411 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1412 register save and restore. The kernel will only save
1413 legacy floating-point registers on task switch.
1da177e4 1414
191679fd
AK
1415 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1416
1da177e4 1417 nohlt [BUGS=ARM]
a9913044 1418
cd4f0ef7 1419 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1420 instruction doesn't work correctly and not to
1421 use it.
1422
1423 nohalt [IA-64] Tells the kernel not to use the power saving
1424 function PAL_HALT_LIGHT when idle. This increases
1425 power-consumption. On the positive side, it reduces
1426 interrupt wake-up latency, which may improve performance
1427 in certain environments such as networked servers or
1428 real-time systems.
1429
79bf2bb3
TG
1430 nohz= [KNL] Boottime enable/disable dynamic ticks
1431 Valid arguments: on, off
1432 Default: on
1433
cd4f0ef7 1434 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
8542b200 1435
cd4f0ef7 1436 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1437 disable unhandled interrupt sources.
1438
cd4f0ef7 1439 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1440 broken timer IRQ sources.
1441
1da177e4
LT
1442 noisapnp [ISAPNP] Disables ISA PnP code.
1443
1444 noinitrd [RAM] Tells the kernel not to load any configured
1445 initial RAM disk.
1446
1447 nointroute [IA-64]
1448
0aa366f3
TL
1449 nojitter [IA64] Disables jitter checking for ITC timers.
1450
cd4f0ef7 1451 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1452
cd4f0ef7 1453 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1454
1da177e4
LT
1455 noltlbs [PPC] Do not use large page/tlb entries for kernel
1456 lowmem mapping on PPC40x.
1457
312f1f01
H
1458 nomca [IA-64] Disable machine check abort handling
1459
cd4f0ef7 1460 nomce [X86-32] Machine Check Exception
abe37e5a 1461
83d7384f
AS
1462 nomfgpt [X86-32] Disable Multi-Function General Purpose
1463 Timer usage (for AMD Geode machines).
1464
cd4f0ef7 1465 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1466
cd4f0ef7 1467 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1468 with UP alternatives
1469
1da177e4
LT
1470 noresidual [PPC] Don't use residual data on PReP machines.
1471
a9913044
RD
1472 noresume [SWSUSP] Disables resume and restores original swap
1473 space.
1474
1da177e4
LT
1475 no-scroll [VGA] Disables scrollback.
1476 This is required for the Braillex ib80-piezo Braille
1477 reader made by F.H. Papenmeier (Germany).
1478
1479 nosbagart [IA-64]
1480
cd4f0ef7 1481 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1482
61ec7567
LB
1483 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1484 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1485
97842216
DJ
1486 nosoftlockup [KNL] Disable the soft-lockup detector.
1487
1da177e4
LT
1488 nosync [HW,M68K] Disables sync negotiation for all devices.
1489
cd4f0ef7 1490 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1491
1492 nousb [USB] Disable the USB subsystem
1493
1494 nowb [ARM]
a9913044 1495
a6c75b86
FY
1496 nptcg= [IA64] Override max number of concurrent global TLB
1497 purges which is reported from either PAL_VM_SUMMARY or
1498 SAL PALO.
1499
f0c0b2b8
KH
1500 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1501 one of ['zone', 'node', 'default'] can be specified
1502 This can be set from sysctl after boot.
1503 See Documentation/sysctl/vm.txt for details.
1504
a61c2d78
DJ
1505 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1506
3ef0e1f8
AS
1507 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1508 Rather than timing out after 20 ms if an EC
1509 command is not properly ACKed, override the length
1510 of the timeout. We have interrupts disabled while
1511 waiting for the ACK, so if this is set too high
1512 interrupts *may* be lost!
1513
1da177e4
LT
1514 opl3= [HW,OSS]
1515 Format: <io>
1516
1da177e4
LT
1517 oprofile.timer= [HW]
1518 Use timer interrupt instead of performance counters
1519
1da177e4
LT
1520 osst= [HW,SCSI] SCSI Tape Driver
1521 Format: <buffer_size>,<write_threshold>
1522 See also Documentation/scsi/st.txt.
1523
1524 panic= [KNL] Kernel behaviour on panic
1525 Format: <timeout>
1526
1527 parkbd.port= [HW] Parallel port number the keyboard adapter is
1528 connected to, default is 0.
1529 Format: <parport#>
1530 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1531 0 for XT, 1 for AT (default is AT).
a9913044
RD
1532 Format: <mode>
1533
1534 parport= [HW,PPT] Specify parallel ports. 0 disables.
1535 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1536 Use 'auto' to force the driver to use any
1537 IRQ/DMA settings detected (the default is to
1538 ignore detected IRQ/DMA settings because of
1539 possible conflicts). You can specify the base
1540 address, IRQ, and DMA settings; IRQ and DMA
1541 should be numbers, or 'auto' (for using detected
1542 settings on that particular port), or 'nofifo'
1543 (to avoid using a FIFO even if it is detected).
1544 Parallel ports are assigned in the order they
1545 are specified on the command line, starting
1546 with parport0.
1547
1548 parport_init_mode= [HW,PPT]
1549 Configure VIA parallel port to operate in
1550 a specific mode. This is necessary on Pegasos
1551 computer where firmware has no options for setting
1552 up parallel port mode and sets it to spp.
1553 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1554 Format: [spp|ps2|epp|ecp|ecpepp]
1555
a9913044
RD
1556 pas2= [HW,OSS] Format:
1557 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1558
1da177e4
LT
1559 pas16= [HW,SCSI]
1560 See header of drivers/scsi/pas16.c.
1561
dd287796
AM
1562 pause_on_oops=
1563 Halt all CPUs after the first oops has been printed for
1564 the specified number of seconds. This is to be used if
1565 your oopses keep scrolling off the screen.
1566
1da177e4
LT
1567 pcbit= [HW,ISDN]
1568
1569 pcd. [PARIDE]
1570 See header of drivers/block/paride/pcd.c.
1571 See also Documentation/paride.txt.
1572
a9913044 1573 pci=option[,option...] [PCI] various PCI subsystem options:
cd4f0ef7
AC
1574 off [X86-32] don't probe for the PCI bus
1575 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1576 the hardware directly. Use this if your machine
1577 has a non-standard PCI host bridge.
cd4f0ef7 1578 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1579 hardware access methods are allowed. Use this
1580 if you experience crashes upon bootup and you
1581 suspect they are caused by the BIOS.
cd4f0ef7 1582 conf1 [X86-32] Force use of PCI Configuration
a9913044 1583 Mechanism 1.
cd4f0ef7 1584 conf2 [X86-32] Force use of PCI Configuration
a9913044 1585 Mechanism 2.
7f785763
RD
1586 noaer [PCIE] If the PCIEAER kernel config parameter is
1587 enabled, this kernel boot option can be used to
1588 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1589 nodomains [PCI] Disable support for multiple PCI
1590 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1591 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1592 Configuration
309e57df
MW
1593 nomsi [MSI] If the PCI_MSI kernel config parameter is
1594 enabled, this kernel boot option can be used to
1595 disable the use of MSI interrupts system-wide.
cd4f0ef7 1596 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1597 routing table. These calls are known to be buggy
1598 on several machines and they hang the machine
1599 when used, but on other computers it's the only
1600 way to get the interrupt routing table. Try
1601 this option if the kernel is unable to allocate
1602 IRQs or discover secondary PCI buses on your
1603 motherboard.
cd4f0ef7 1604 rom [X86-32] Assign address space to expansion ROMs.
a9913044
RD
1605 Use with caution as certain devices share
1606 address decoders between ROMs and other
1607 resources.
bb71ad88
GH
1608 norom [X86-32,X86_64] Do not assign address space to
1609 expansion ROMs that do not already have
1610 BIOS assigned address ranges.
cd4f0ef7 1611 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
a9913044
RD
1612 assigned automatically to PCI devices. You can
1613 make the kernel exclude IRQs of your ISA cards
1614 this way.
cd4f0ef7 1615 pirqaddr=0xAAAAA [X86-32] Specify the physical address
a9913044
RD
1616 of the PIRQ table (normally generated
1617 by the BIOS) if it is outside the
1618 F0000h-100000h range.
cd4f0ef7 1619 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
a9913044
RD
1620 useful if the kernel is unable to find your
1621 secondary buses and you want to tell it
1622 explicitly which ones they are.
cd4f0ef7 1623 assign-busses [X86-32] Always assign all PCI bus
a9913044
RD
1624 numbers ourselves, overriding
1625 whatever the firmware may have done.
cd4f0ef7 1626 usepirqmask [X86-32] Honor the possible IRQ mask stored
a9913044
RD
1627 in the BIOS $PIR table. This is needed on
1628 some systems with broken BIOSes, notably
1629 some HP Pavilion N5400 and Omnibook XE3
1630 notebooks. This will have no effect if ACPI
1631 IRQ routing is enabled.
cd4f0ef7 1632 noacpi [X86-32] Do not use ACPI for IRQ routing
a9913044 1633 or for PCI scanning.
62f420f8
GH
1634 use_crs [X86-32] Use _CRS for PCI resource
1635 allocation.
a9913044
RD
1636 routeirq Do IRQ routing for all PCI devices.
1637 This is normally done in pci_enable_device(),
1638 so this option is a temporary workaround
1639 for broken drivers that don't call it.
13a6ddb0
YL
1640 skip_isa_align [X86] do not align io start addr, so can
1641 handle more pci cards
a9913044
RD
1642 firmware [ARM] Do not re-enumerate the bus but instead
1643 just use the configuration from the
1644 bootloader. This is currently used on
1645 IXP2000 systems where the bus has to be
1646 configured a certain way for adjunct CPUs.
0637a70a
AK
1647 noearly [X86] Don't do any early type 1 scanning.
1648 This might help on some broken boards which
1649 machine check when some devices' config space
1650 is read. But various workarounds are disabled
1651 and some IOMMU drivers will not work.
6b4b78fe
MD
1652 bfsort Sort PCI devices into breadth-first order.
1653 This sorting is done to get a device
1654 order compatible with older (<= 2.4) kernels.
1655 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1656 cbiosize=nn[KMG] The fixed amount of bus space which is
1657 reserved for the CardBus bridge's IO window.
1658 The default value is 256 bytes.
1659 cbmemsize=nn[KMG] The fixed amount of bus space which is
1660 reserved for the CardBus bridge's memory
1661 window. The default value is 64 megabytes.
6b4b78fe 1662
1da177e4
LT
1663 pcmv= [HW,PCMCIA] BadgePAD 4
1664
1665 pd. [PARIDE]
1666 See Documentation/paride.txt.
1667
1668 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1669 boot time.
1670 Format: { 0 | 1 }
1671 See arch/parisc/kernel/pdc_chassis.c
1672
1673 pf. [PARIDE]
1674 See Documentation/paride.txt.
1675
1676 pg. [PARIDE]
1677 See Documentation/paride.txt.
1678
1679 pirq= [SMP,APIC] Manual mp-table setup
1680 See Documentation/i386/IO-APIC.txt.
1681
1682 plip= [PPT,NET] Parallel port network link
1683 Format: { parport<nr> | timid | 0 }
1684 See also Documentation/parport.txt.
1685
de32a243
TG
1686 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1687 Override pmtimer IOPort with a hex value.
1688 e.g. pmtmr=0x508
1689
1da177e4
LT
1690 pnpacpi= [ACPI]
1691 { off }
1692
1693 pnpbios= [ISAPNP]
1694 { on | off | curr | res | no-curr | no-res }
1695
1696 pnp_reserve_irq=
1697 [ISAPNP] Exclude IRQs for the autoconfiguration
1698
1699 pnp_reserve_dma=
1700 [ISAPNP] Exclude DMAs for the autoconfiguration
1701
1702 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1703 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1704
1705 pnp_reserve_mem=
a9913044
RD
1706 [ISAPNP] Exclude memory regions for the
1707 autoconfiguration.
1da177e4
LT
1708 Ranges are in pairs (memory base and size).
1709
45807a1d
IM
1710 print-fatal-signals=
1711 [KNL] debug: print fatal signals
1712 print-fatal-signals=1: print segfault info to
1713 the kernel console.
1714 default: off.
1715
e84845c4
RD
1716 printk.time= Show timing data prefixed to each printk message line
1717 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1718
1da177e4 1719 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1720 Format: [schedule,]<number>
1721 Param: "schedule" - profile schedule points.
1722 Param: <number> - step/bucket size as a power of 2 for
1723 statistical time based profiling.
b3da2a73
MG
1724 Param: "sleep" - profile D-state sleeping (millisecs).
1725 Requires CONFIG_SCHEDSTATS
c0fe2e69 1726 Param: "kvm" - profile VM exits.
1da177e4 1727
a9913044 1728 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1729 Limit processor to maximum C-state
1730 max_cstate=9 overrides any DMI blacklist limit.
1731
41c0d868
LB
1732 processor.nocst [HW,ACPI]
1733 Ignore the _CST method to determine C-states,
1734 instead using the legacy FADT method
1735
1da177e4
LT
1736 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1737 before loading.
1738 See Documentation/ramdisk.txt.
1739
a9913044
RD
1740 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1741 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1742 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1743 per second.
a9913044
RD
1744 psmouse.resetafter= [HW,MOUSE]
1745 Try to reset the device after so many bad packets
1da177e4
LT
1746 (0 = never).
1747 psmouse.resolution=
1748 [HW,MOUSE] Set desired mouse resolution, in dpi.
1749 psmouse.smartscroll=
a9913044 1750 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1751 0 = disabled, 1 = enabled (default).
1752
1753 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1754 Format:
1755 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1756
1757 pt. [PARIDE]
1758 See Documentation/paride.txt.
1759
dc8c8587
KS
1760 pty.legacy_count=
1761 [KNL] Number of legacy pty's. Overwrites compiled-in
1762 default number.
1763
7d2c502f 1764 quiet [KNL] Disable most log messages
a9913044 1765
1da177e4
LT
1766 r128= [HW,DRM]
1767
1768 raid= [HW,RAID]
1769 See Documentation/md.txt.
1770
a9913044 1771 ramdisk_blocksize= [RAM]
1da177e4 1772 See Documentation/ramdisk.txt.
a9913044 1773
1da177e4 1774 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1da177e4
LT
1775 See Documentation/ramdisk.txt.
1776
24aaef8d
RD
1777 rcupdate.blimit= [KNL,BOOT]
1778 Set maximum number of finished RCU callbacks to process
1779 in one batch.
21a1ea9e 1780
24aaef8d
RD
1781 rcupdate.qhimark= [KNL,BOOT]
1782 Set threshold of queued
21a1ea9e
DS
1783 RCU callbacks over which batch limiting is disabled.
1784
24aaef8d
RD
1785 rcupdate.qlowmark= [KNL,BOOT]
1786 Set threshold of queued RCU callbacks below which
1787 batch limiting is re-enabled.
21a1ea9e 1788
ffdfc409
OJ
1789 rdinit= [KNL]
1790 Format: <full_path>
1791 Run specified binary instead of /init from the ramdisk,
1792 used for early userspace startup. See initrd.
1793
cd4f0ef7 1794 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1795 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1796 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1797
46b6d94e
PJ
1798 relax_domain_level=
1799 [KNL, SMP] Set scheduler's default relax_domain_level.
1800 See Documentation/cpusets.txt.
1801
1da177e4
LT
1802 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1803
cd4f0ef7 1804 reservetop= [X86-32]
461a9aff
ZA
1805 Format: nn[KMG]
1806 Reserves a hole at the top of the kernel virtual
1807 address space.
1808
7e96287d
VG
1809 reset_devices [KNL] Force drivers to reset the underlying device
1810 during initialization.
1811
a9913044
RD
1812 resume= [SWSUSP]
1813 Specify the partition device for software suspend
1da177e4 1814
ecbd0da1
RW
1815 resume_offset= [SWSUSP]
1816 Specify the offset from the beginning of the partition
1817 given by "resume=" at which the swap header is located,
1818 in <PAGE_SIZE> units (needed only for swap files).
1819 See Documentation/power/swsusp-and-swap-files.txt
1820
0a7b35cb
MN
1821 retain_initrd [RAM] Keep initrd memory after extraction
1822
1da177e4
LT
1823 rhash_entries= [KNL,NET]
1824 Set number of hash buckets for route cache
1825
1826 riscom8= [HW,SERIAL]
1827 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1828
1829 ro [KNL] Mount root device read-only on boot
1830
1831 root= [KNL] Root filesystem
1832
1833 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1834 mount the root filesystem
1835
1836 rootflags= [KNL] Set root filesystem mount option string
1837
1838 rootfstype= [KNL] Set root filesystem type
1839
cc1ed754
PO
1840 rootwait [KNL] Wait (indefinitely) for root device to show up.
1841 Useful for devices that are detected asynchronously
1842 (e.g. USB and MMC devices).
1843
20510f2f
JM
1844 root_plug.vendor_id=
1845 [ROOTPLUG] Override the default vendor ID
1846
1847 root_plug.product_id=
1848 [ROOTPLUG] Override the default product ID
1849
1850 root_plug.debug=
1851 [ROOTPLUG] Enable debugging output
1852
1da177e4
LT
1853 rw [KNL] Mount root device read-write on boot
1854
1855 S [KNL] Run init in single mode
1856
1857 sa1100ir [NET]
1858 See drivers/net/irda/sa1100_ir.c.
1859
1da177e4 1860 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1861
1da177e4
LT
1862 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1863 Format: <io>[,<timeout>[,<isapnp>]]
1864
1865 scsi_debug_*= [SCSI]
1866 See drivers/scsi/scsi_debug.c.
1867
1868 scsi_default_dev_flags=
1869 [SCSI] SCSI default device flags
1870 Format: <integer>
1871
1872 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1873 Format: <vendor>:<model>:<flags>
1874 (flags are integer value)
1875
6af6632a
RD
1876 scsi_logging_level= [SCSI] a bit mask of logging levels
1877 See drivers/scsi/scsi_logging.h for bits. Also
1878 settable via sysctl at dev.scsi.logging_level
1879 (/proc/sys/dev/scsi/logging_level).
1880 There is also a nice 'scsi_logging_level' script in the
1881 S390-tools package, available for download at
1882 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1883
3e082a91
MW
1884 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1885 discovered. async scans them in kernel threads,
1886 allowing boot to proceed. none ignores them, expecting
1887 user space to do the scan.
1888
1da177e4
LT
1889 selinux [SELINUX] Disable or enable SELinux at boot time.
1890 Format: { "0" | "1" }
1891 See security/selinux/Kconfig help text.
1892 0 -- disable.
1893 1 -- enable.
1894 Default value is set via kernel config option.
1895 If enabled at boot time, /selinux/disable can be used
1896 later to disable prior to initial policy load.
1897
4e5ab4cb
JM
1898 selinux_compat_net =
1899 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1900 Format: { "0" | "1" }
1901 0 -- use new secmark-based packet controls
1902 1 -- use legacy packet controls
1903 Default value is 0 (preferred).
1904 Value can be changed at runtime via
1905 /selinux/compat_net.
4e5ab4cb 1906
cd4f0ef7 1907 serialnumber [BUGS=X86-32]
1da177e4 1908
1da177e4
LT
1909 shapers= [NET]
1910 Maximal number of shapers.
a9913044 1911
1da177e4
LT
1912 sim710= [SCSI,HW]
1913 See header of drivers/scsi/sim710.c.
1914
1915 simeth= [IA-64]
1916 simscsi=
a9913044 1917
1da177e4
LT
1918 slram= [HW,MTD]
1919
f0630fff
CL
1920 slub_debug[=options[,slabs]] [MM, SLUB]
1921 Enabling slub_debug allows one to determine the
1922 culprit if slab objects become corrupted. Enabling
1923 slub_debug can create guard zones around objects and
1924 may poison objects when not in use. Also tracks the
1925 last alloc / free. For more information see
1926 Documentation/vm/slub.txt.
c1aee215
CL
1927
1928 slub_max_order= [MM, SLUB]
f0630fff
CL
1929 Determines the maximum allowed order for slabs.
1930 A high setting may cause OOMs due to memory
1931 fragmentation. For more information see
1932 Documentation/vm/slub.txt.
c1aee215
CL
1933
1934 slub_min_objects= [MM, SLUB]
f0630fff
CL
1935 The minimum number of objects per slab. SLUB will
1936 increase the slab order up to slub_max_order to
1937 generate a sufficiently large slab able to contain
1938 the number of objects indicated. The higher the number
1939 of objects the smaller the overhead of tracking slabs
1940 and the less frequently locks need to be acquired.
c1aee215
CL
1941 For more information see Documentation/vm/slub.txt.
1942
1943 slub_min_order= [MM, SLUB]
1944 Determines the mininum page order for slabs. Must be
f0630fff 1945 lower than slub_max_order.
c1aee215
CL
1946 For more information see Documentation/vm/slub.txt.
1947
1948 slub_nomerge [MM, SLUB]
f0630fff 1949 Disable merging of slabs with similar size. May be
c1aee215 1950 necessary if there is some reason to distinguish
f0630fff
CL
1951 allocs to different slabs. Debug options disable
1952 merging on their own.
c1aee215
CL
1953 For more information see Documentation/vm/slub.txt.
1954
1da177e4
LT
1955 smart2= [HW]
1956 Format: <io1>[,<io2>[,...,<io8>]]
1957
cd4f0ef7 1958 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
1959 attempt to substitute SMP alternatives once at boot.
1960
d0d4f69b
BH
1961 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1962 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1963 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1964 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1965 smsc-ircc2.ircc_irq= [HW] IRQ line
1966 smsc-ircc2.ircc_dma= [HW] DMA channel
1967 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1968 0: Toshiba Satellite 1800 (GP data pin select)
1969 1: Fast pin select (default)
1970 2: ATC IRMode
1971
1da177e4
LT
1972 snd-ad1816a= [HW,ALSA]
1973
1974 snd-ad1848= [HW,ALSA]
1975
1976 snd-ali5451= [HW,ALSA]
1977
1978 snd-als100= [HW,ALSA]
1979
1980 snd-als4000= [HW,ALSA]
1981
1982 snd-azt2320= [HW,ALSA]
1983
1984 snd-cmi8330= [HW,ALSA]
1985
1986 snd-cmipci= [HW,ALSA]
1987
1988 snd-cs4231= [HW,ALSA]
1989
1990 snd-cs4232= [HW,ALSA]
1991
1992 snd-cs4236= [HW,ALSA]
1993
1994 snd-cs4281= [HW,ALSA]
1995
1996 snd-cs46xx= [HW,ALSA]
1997
1998 snd-dt019x= [HW,ALSA]
1999
2000 snd-dummy= [HW,ALSA]
2001
2002 snd-emu10k1= [HW,ALSA]
2003
2004 snd-ens1370= [HW,ALSA]
2005
2006 snd-ens1371= [HW,ALSA]
2007
2008 snd-es968= [HW,ALSA]
2009
2010 snd-es1688= [HW,ALSA]
2011
2012 snd-es18xx= [HW,ALSA]
2013
2014 snd-es1938= [HW,ALSA]
2015
2016 snd-es1968= [HW,ALSA]
2017
2018 snd-fm801= [HW,ALSA]
2019
2020 snd-gusclassic= [HW,ALSA]
2021
2022 snd-gusextreme= [HW,ALSA]
2023
2024 snd-gusmax= [HW,ALSA]
2025
2026 snd-hdsp= [HW,ALSA]
2027
2028 snd-ice1712= [HW,ALSA]
2029
2030 snd-intel8x0= [HW,ALSA]
2031
2032 snd-interwave= [HW,ALSA]
2033
2034 snd-interwave-stb=
2035 [HW,ALSA]
2036
2037 snd-korg1212= [HW,ALSA]
2038
2039 snd-maestro3= [HW,ALSA]
2040
2041 snd-mpu401= [HW,ALSA]
2042
2043 snd-mtpav= [HW,ALSA]
2044
2045 snd-nm256= [HW,ALSA]
2046
2047 snd-opl3sa2= [HW,ALSA]
2048
2049 snd-opti92x-ad1848=
2050 [HW,ALSA]
2051
2052 snd-opti92x-cs4231=
2053 [HW,ALSA]
2054
2055 snd-opti93x= [HW,ALSA]
2056
2057 snd-pmac= [HW,ALSA]
2058
2059 snd-rme32= [HW,ALSA]
2060
2061 snd-rme96= [HW,ALSA]
2062
2063 snd-rme9652= [HW,ALSA]
2064
2065 snd-sb8= [HW,ALSA]
2066
2067 snd-sb16= [HW,ALSA]
2068
2069 snd-sbawe= [HW,ALSA]
2070
2071 snd-serial= [HW,ALSA]
2072
2073 snd-sgalaxy= [HW,ALSA]
2074
2075 snd-sonicvibes= [HW,ALSA]
2076
2077 snd-sun-amd7930=
2078 [HW,ALSA]
2079
2080 snd-sun-cs4231= [HW,ALSA]
2081
2082 snd-trident= [HW,ALSA]
2083
2084 snd-usb-audio= [HW,ALSA,USB]
2085
2086 snd-via82xx= [HW,ALSA]
2087
2088 snd-virmidi= [HW,ALSA]
2089
2090 snd-wavefront= [HW,ALSA]
2091
2092 snd-ymfpci= [HW,ALSA]
a9913044 2093
9c44bc03
IM
2094 softlockup_panic=
2095 [KNL] Should the soft-lockup detector generate panics.
2096
1da177e4
LT
2097 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2098 See Documentation/sonypi.txt
2099
2100 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2101 See Documentation/specialix.txt.
2102
2103 spia_io_base= [HW,MTD]
2104 spia_fio_base=
2105 spia_pedr=
2106 spia_peddr=
2107
2108 sscape= [HW,OSS]
2109 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2110
1da177e4
LT
2111 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2112 See Documentation/scsi/st.txt.
2113
1da177e4
LT
2114 sti= [PARISC,HW]
2115 Format: <num>
2116 Set the STI (builtin display/keyboard on the HP-PARISC
2117 machines) console (graphic card) which should be used
2118 as the initial boot-console.
2119 See also comment in drivers/video/console/sticore.c.
2120
2121 sti_font= [HW]
2122 See comment in drivers/video/console/sticore.c.
2123
2124 stifb= [HW]
2125 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2126
42a7fc4a
GB
2127 sunrpc.pool_mode=
2128 [NFS]
2129 Control how the NFS server code allocates CPUs to
2130 service thread pools. Depending on how many NICs
2131 you have and where their interrupts are bound, this
2132 option will affect which CPUs will do NFS serving.
2133 Note: this parameter cannot be changed while the
2134 NFS server is running.
2135
2136 auto the server chooses an appropriate mode
2137 automatically using heuristics
2138 global a single global pool contains all CPUs
2139 percpu one pool for each CPU
2140 pernode one pool for each NUMA node (equivalent
2141 to global on non-NUMA machines)
2142
1da177e4 2143 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2144
1da177e4
LT
2145 switches= [HW,M68k]
2146
2147 sym53c416= [HW,SCSI]
2148 See header of drivers/scsi/sym53c416.c.
2149
5d6f647f
IM
2150 sysrq_always_enabled
2151 [KNL]
2152 Ignore sysrq setting - this boot parameter will
2153 neutralize any effect of /proc/sys/kernel/sysrq.
2154 Useful for debugging.
2155
1da177e4
LT
2156 t128= [HW,SCSI]
2157 See header of drivers/scsi/t128.c.
2158
2159 tdfx= [HW,DRM]
2160
77437fd4
DB
2161 test_suspend= [SUSPEND]
2162 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2163 standby suspend) as the system sleep state to briefly
2164 enter during system startup. The system is woken from
2165 this state using a wakeup-capable RTC alarm.
2166
1da177e4
LT
2167 thash_entries= [KNL,NET]
2168 Set number of hash buckets for TCP connection
2169
f8707ec9
LB
2170 thermal.act= [HW,ACPI]
2171 -1: disable all active trip points in all thermal zones
2172 <degrees C>: override all lowest active trip points
2173
c52a7419
LB
2174 thermal.crt= [HW,ACPI]
2175 -1: disable all critical trip points in all thermal zones
22a94d79 2176 <degrees C>: override all critical trip points
c52a7419 2177
f5487145
LB
2178 thermal.nocrt= [HW,ACPI]
2179 Set to disable actions on ACPI thermal zone
2180 critical and hot trip points.
2181
72b33ef8
LB
2182 thermal.off= [HW,ACPI]
2183 1: disable ACPI thermal control
2184
a70cdc52
LB
2185 thermal.psv= [HW,ACPI]
2186 -1: disable all passive trip points
2187 <degrees C>: override all passive trip points to this value
2188
730ff34d
LB
2189 thermal.tzp= [HW,ACPI]
2190 Specify global default ACPI thermal zone polling rate
2191 <deci-seconds>: poll all this frequency
2192 0: no polling (default)
2193
1da177e4
LT
2194 tmscsim= [HW,SCSI]
2195 See comment before function dc390_setup() in
2196 drivers/scsi/tmscsim.c.
2197
2198 tp720= [HW,PS2]
2199
2200 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2201 Format:
2202 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2203
a9913044
RD
2204 turbografx.map[2|3]= [HW,JOY]
2205 TurboGraFX parallel port interface
2206 Format:
2207 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2208 See also Documentation/input/joystick-parport.txt
2209
2210 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2211 See header of drivers/scsi/u14-34f.c.
2212
2213 uart401= [HW,OSS]
2214 Format: <io>,<irq>
2215
2216 uart6850= [HW,OSS]
2217 Format: <io>,<irq>
2218
5f8364b7
AS
2219 uhci-hcd.ignore_oc=
2220 [USB] Ignore overcurrent events (default N).
2221 Some badly-designed motherboards generate lots of
2222 bogus events, for ports that aren't wired to
2223 anything. Set this parameter to avoid log spamming.
2224 Note that genuine overcurrent events won't be
2225 reported either.
2226
e3a61b0a
SA
2227 unknown_nmi_panic
2228 [X86-32,X86-64]
2229 Set unknown_nmi_panic=1 early on boot.
2230
b5e795f8
AS
2231 usbcore.autosuspend=
2232 [USB] The autosuspend time delay (in seconds) used
2233 for newly-detected USB devices (default 2). This
2234 is the time required before an idle device will be
2235 autosuspended. Devices for which the delay is set
eaafbc3a 2236 to a negative value won't be autosuspended at all.
b5e795f8 2237
1da177e4
LT
2238 usbhid.mousepoll=
2239 [USBHID] The interval which mice are to be polled at.
a9913044 2240
200001eb
PJ
2241 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2242 kernel's map of available physical RAM.
2243
cd4f0ef7 2244 vdso= [X86-32,SH,x86-64]
1dbf527c 2245 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2246 vdso=1: enable VDSO (default)
2247 vdso=0: disable VDSO mapping
2248
af65d648
RM
2249 vdso32= [X86-32,X86-64]
2250 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2251 vdso32=1: enable 32-bit VDSO (default)
2252 vdso32=0: disable 32-bit VDSO mapping
2253
d080d397
YI
2254 vector= [IA-64,SMP]
2255 vector=percpu: enable percpu vector domain
2256
1da177e4
LT
2257 video= [FB] Frame buffer configuration
2258 See Documentation/fb/modedb.txt.
2259
cd4f0ef7 2260 vga= [BOOT,X86-32] Select a particular video mode
a9913044
RD
2261 See Documentation/i386/boot.txt and
2262 Documentation/svga.txt.
1da177e4
LT
2263 Use vga=ask for menu.
2264 This is actually a boot loader parameter; the value is
2265 passed to the kernel using a special protocol.
2266
a9913044 2267 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2268 size of <nn>. This can be used to increase the
2269 minimum size (128MB on x86). It can also be used to
2270 decrease the size and leave more room for directly
2271 mapped kernel RAM.
2272
585c3047
PO
2273 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2274 Format: <command>
1da177e4 2275
585c3047
PO
2276 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2277 Format: <command>
2278
2279 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2280 Format: <command>
a9913044 2281
1da177e4
LT
2282 waveartist= [HW,OSS]
2283 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2284
1da177e4
LT
2285 wd33c93= [HW,SCSI]
2286 See header of drivers/scsi/wd33c93.c.
2287
2288 wd7000= [HW,SCSI]
2289 See header of drivers/scsi/wd7000.c.
2290
2291 wdt= [WDT] Watchdog
8dfe9c21 2292 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2293
2294 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2295 xd_geo= See header of drivers/block/xd.c.
2296
2297 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2298 Format:
2299 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2300
a62eaf15
AK
2301 norandmaps Don't use address space randomization
2302 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2303
a9913044 2304______________________________________________________________________
1da177e4
LT
2305
2306TODO:
2307
2308 Add documentation for ALSA options.
2309 Add more DRM drivers.