]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blame - Documentation/kernel-parameters.txt
usb gadget: link fixes for network gadget
[mirror_ubuntu-artful-kernel.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,
1da177e4
LT
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
f989106c
ZR
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
234
cd4f0ef7 235 acpi_pm_good [X86-32,X86-64]
5d0cf410
JS
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
239
c99c108a
CE
240 agp= [AGP]
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
245
66759a01
CE
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
a9913044
RD
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
66759a01
CE
250 The kernel tries to set a reasonable default.
251
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
255
1da177e4
LT
256 ad1848= [HW,OSS]
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
258
1da177e4
LT
259 advansys= [HW,SCSI]
260 See header of drivers/scsi/advansys.c.
261
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
264
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
a9913044 268
1da177e4
LT
269 aha152x= [HW,SCSI]
270 See Documentation/scsi/aha152x.txt.
271
272 aha1542= [HW,SCSI]
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
274
275 aic7xxx= [HW,SCSI]
276 See Documentation/scsi/aic7xxx.txt.
277
278 aic79xx= [HW,SCSI]
279 See Documentation/scsi/aic79xx.txt.
280
54b4cbd2
JR
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
283 Possible values are:
54b4cbd2
JR
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
286 domain)
afa9fdc2
FT
287 fullflush - enable flushing of IO/TLB entries when
288 they are unmapped. Otherwise they are
289 flushed before they will be reused, which
290 is a lot of faster
291
54b4cbd2
JR
292 amd_iommu_size= [HW,X86-64]
293 Define the size of the aperture for the AMD IOMMU
294 driver. Possible values are:
295 '32M', '64M' (default), '128M', '256M', '512M', '1G'
296
1da177e4
LT
297 amijoy.map= [HW,JOY] Amiga joystick support
298 Map of devices attached to JOY0DAT and JOY1DAT
299 Format: <a>,<b>
300 See also Documentation/kernel/input/joystick.txt
301
302 analog.map= [HW,JOY] Analog joystick and gamepad support
303 Specifies type or capabilities of an analog joystick
304 connected to one of 16 gameports
305 Format: <type1>,<type2>,..<type16>
306
a9913044
RD
307 apc= [HW,SPARC]
308 Power management functions (SPARCstation-4/5 + deriv.)
1da177e4
LT
309 Format: noidle
310 Disable APC CPU standby support. SPARCstation-Fox does
311 not play well with APC CPU idle - disable it if you have
312 APC and your system crashes randomly.
313
c8facbb6
RD
314 apic= [APIC,i386] Advanced Programmable Interrupt Controller
315 Change the output verbosity whilst booting
1da177e4
LT
316 Format: { quiet (default) | verbose | debug }
317 Change the amount of debugging information output
318 when initialising the APIC and IO-APIC components.
a9913044 319
1da177e4 320 apm= [APM] Advanced Power Management
71f77055 321 See header of arch/x86/kernel/apm_32.c.
1da177e4 322
1da177e4
LT
323 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
324 Format: <io>,<irq>,<nodeID>
325
326 ataflop= [HW,M68k]
327
328 atarimouse= [HW,MOUSE] Atari Mouse
329
330 atascsi= [HW,SCSI] Atari SCSI
331
332 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
333 EzKey and similar keyboards
334
335 atkbd.reset= [HW] Reset keyboard during initialization
336
a9913044
RD
337 atkbd.set= [HW] Select keyboard code set
338 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
LT
339
340 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
341 keyboards
342
343 atkbd.softraw= [HW] Choose between synthetic and real raw mode
344 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
RD
345
346 atkbd.softrepeat= [HW]
347 Use software keyboard repeat
1da177e4
LT
348
349 autotest [IA64]
350
1da177e4
LT
351 baycom_epp= [HW,AX25]
352 Format: <io>,<mode>
a9913044 353
1da177e4
LT
354 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
355 Format: <io>,<mode>
356 See header of drivers/net/hamradio/baycom_par.c.
357
a9913044
RD
358 baycom_ser_fdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
1da177e4
LT
360 Format: <io>,<irq>,<mode>[,<baud>]
361 See header of drivers/net/hamradio/baycom_ser_fdx.c.
362
a9913044
RD
363 baycom_ser_hdx= [HW,AX25]
364 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
1da177e4
LT
365 Format: <io>,<irq>,<mode>
366 See header of drivers/net/hamradio/baycom_ser_hdx.c.
367
bfe8df3d
RD
368 boot_delay= Milliseconds to delay each printk during boot.
369 Values larger than 10 seconds (10000) are changed to
370 no delay (0).
371 Format: integer
372
35fc908d
AH
373 bootmem_debug [KNL] Enable bootmem allocator debug messages.
374
1da177e4 375 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
a9913044
RD
376 bttv.radio= Most important insmod options are available as
377 kernel args too.
1da177e4
LT
378 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
379 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
380
381 BusLogic= [HW,SCSI]
382 See drivers/scsi/BusLogic.c, comment before function
383 BusLogic_ParseDriverOptions().
384
385 c101= [NET] Moxa C101 synchronous serial card
386
cd4f0ef7 387 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
1da177e4
LT
388 Sometimes CPU hardware bugs make them report the cache
389 size incorrectly. The kernel will attempt work arounds
390 to fix known problems, but for some CPUs it is not
391 possible to determine what the correct size should be.
392 This option provides an override for these situations.
393
076c54c5
AD
394 security= [SECURITY] Choose a security module to enable at boot.
395 If this boot parameter is not specified, only the first
396 security module asking for security registration will be
397 loaded. An invalid security module name will be treated
398 as if no module has been chosen.
399
20510f2f
JM
400 capability.disable=
401 [SECURITY] Disable capabilities. This would normally
402 be used only if an alternative security model is to be
403 configured. Potentially dangerous and should only be
404 used if you are entirely sure of the consequences.
405
14ff56bb
SO
406 ccw_timeout_log [S390]
407 See Documentation/s390/CommonIO for details.
1da177e4 408
8bab8dde
PM
409 cgroup_disable= [KNL] Disable a particular controller
410 Format: {name of the controller(s) to disable}
411 {Currently supported controllers - "memory"}
412
1da177e4
LT
413 checkreqprot [SELINUX] Set initial checkreqprot flag value.
414 Format: { "0" | "1" }
415 See security/selinux/Kconfig help text.
a9913044
RD
416 0 -- check protection applied by kernel (includes
417 any implied execute protection).
1da177e4
LT
418 1 -- check protection requested by application.
419 Default value is set via a kernel config option.
a9913044
RD
420 Value can be changed at runtime via
421 /selinux/checkreqprot.
422
661ca0da
SO
423 cio_ignore= [S390]
424 See Documentation/s390/CommonIO for details.
425
cd4f0ef7 426 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 427 [Deprecated]
3f6dee9b 428 Forces specified clocksource (if available) to be used
734efb46 429 when calculating gettimeofday(). If specified
3f6dee9b 430 clocksource is not available, it defaults to PIT.
1da177e4
LT
431 Format: { pit | tsc | cyclone | pmtmr }
432
3d6ac984
RD
433 clocksource= [GENERIC_TIME] Override the default clocksource
434 Format: <string>
435 Override the default clocksource and use the clocksource
436 with the name specified.
437 Some clocksource names to choose from, depending on
438 the platform:
439 [all] jiffies (this is the base, fallback clocksource)
440 [ACPI] acpi_pm
441 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
442 pxa_timer,timer3,32k_counter,timer0_1
443 [AVR32] avr32
cd4f0ef7 444 [X86-32] pit,hpet,tsc,vmi-timer;
3d6ac984
RD
445 scx200_hrt on Geode; cyclone on IBM x440
446 [MIPS] MIPS
447 [PARISC] cr16
448 [S390] tod
449 [SH] SuperH
450 [SPARC64] tick
451 [X86-64] hpet,tsc
452
ac72e788
AK
453 clearcpuid=BITNUM [X86]
454 Disable CPUID feature X for the kernel. See
455 include/asm-x86/cpufeature.h for the valid bit numbers.
456 Note the Linux specific bits are not necessarily
457 stable over kernel options, but the vendor specific
458 ones should be.
459 Also note that user programs calling CPUID directly
460 or using the feature without checking anything
461 will still see it. This just prevents it from
462 being used by the kernel or shown in /proc/cpuinfo.
463 Also note the kernel might malfunction if you disable
464 some critical bits.
465
a25bd949
AV
466 code_bytes [IA32/X86_64] How many bytes of object code to print
467 in an oops report.
86c41837
CE
468 Range: 0 - 8192
469 Default: 64
470
b17530bd
TG
471 hpet= [X86-32,HPET] option to control HPET usage
472 Format: { enable (default) | disable | force }
473 disable: disable HPET and use PIT instead
d79a5f80
CC
474 force: allow force enabled of undocumented chips (ICH4,
475 VIA, nVidia)
1da177e4 476
1da177e4 477 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
478 Format:
479 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
480
481 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
482 Format: <io>[,<irq>]
483
a9913044
RD
484 com90xx= [HW,NET]
485 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
486 Format: <io>[,<irq>[,<memstart>]]
487
488 condev= [HW,S390] console device
489 conmode=
a9913044 490
1da177e4
LT
491 console= [KNL] Output console device and options.
492
493 tty<n> Use the virtual console device <n>.
494
495 ttyS<n>[,options]
f1a1c2dc 496 ttyUSB0[,options]
1da177e4 497 Use the specified serial port. The options are of
f1a1c2dc
RD
498 the form "bbbbpnf", where "bbbb" is the baud rate,
499 "p" is parity ("n", "o", or "e"), "n" is number of
500 bits, and "f" is flow control ("r" for RTS or
501 omit it). Default is "9600n8".
502
503 See Documentation/serial-console.txt for more
504 information. See
505 Documentation/networking/netconsole.txt for an
506 alternative.
1da177e4 507
18a8bd94
YL
508 uart[8250],io,<addr>[,options]
509 uart[8250],mmio,<addr>[,options]
1da177e4
LT
510 Start an early, polled-mode console on the 8250/16550
511 UART at the specified I/O port or MMIO address,
512 switching to the matching ttyS device later. The
513 options are the same as for ttyS, above.
514
f7511d5f
ST
515 If the device connected to the port is not a TTY but a braille
516 device, prepend "brl," before the device type, for instance
517 console=brl,ttyS0
518 For now, only VisioBraille is supported.
519
18a8bd94
YL
520 earlycon= [KNL] Output early console device and options.
521 uart[8250],io,<addr>[,options]
522 uart[8250],mmio,<addr>[,options]
523 Start an early, polled-mode console on the 8250/16550
524 UART at the specified I/O port or MMIO address.
525 The options are the same as for ttyS, above.
526
8f4ce8c3
AS
527 no_console_suspend
528 [HW] Never suspend the console
529 Disable suspending of consoles during suspend and
530 hibernate operations. Once disabled, debugging
531 messages can reach various consoles while the rest
532 of the system is being put to sleep (ie, while
533 debugging driver suspend/resume hooks). This may
534 not work reliably with all consoles, but is known
535 to work with serial and VGA consoles.
536
1da177e4 537 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
538 Format:
539 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 540
dc009d92
EB
541 crashkernel=nn[KMG]@ss[KMG]
542 [KNL] Reserve a chunk of physical memory to
543 hold a kernel to switch to with kexec on panic.
544
fb391599
BW
545 crashkernel=range1:size1[,range2:size2,...][@offset]
546 [KNL] Same as above, but depends on the memory
547 in the running system. The syntax of range is
548 start-[end] where start and end are both
549 a memory unit (amount[KMG]). See also
550 Documentation/kdump/kdump.txt for a example.
551
1da177e4
LT
552 cs4232= [HW,OSS]
553 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
554
555 cs89x0_dma= [HW,NET]
556 Format: <dma>
557
558 cs89x0_media= [HW,NET]
559 Format: { rj45 | aui | bnc }
a9913044 560
a9913044 561 dasd= [HW,NET]
1da177e4
LT
562 See header of drivers/s390/block/dasd_devmap.c.
563
564 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
565 (one device per port)
566 Format: <port#>,<type>
567 See also Documentation/input/joystick-parport.txt
568
569 debug [KNL] Enable kernel debugging (events log level).
570
cae2ed9a
IM
571 debug_locks_verbose=
572 [KNL] verbose self-tests
573 Format=<0|1>
574 Print debugging info while doing the locking API
575 self-tests.
576 We default to 0 (no extra messages), setting it to
577 1 will print _a lot_ more information - normally
578 only useful to kernel developers.
579
3ac7fe5a
TG
580 debug_objects [KNL] Enable object debugging
581
d3af01f1
TG
582 debugpat [X86] Enable PAT debugging
583
2d27a966 584 decnet.addr= [HW,NET]
1da177e4
LT
585 Format: <area>[,<node>]
586 See also Documentation/networking/decnet.txt.
587
ecb77fa9 588 vt.default_blu= [VT]
55ff9780
AD
589 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
590 Change the default blue palette of the console.
591 This is a 16-member array composed of values
592 ranging from 0-255.
593
ecb77fa9 594 vt.default_grn= [VT]
55ff9780
AD
595 Format: <green0>,<green1>,<green2>,...,<green15>
596 Change the default green palette of the console.
597 This is a 16-member array composed of values
598 ranging from 0-255.
599
ecb77fa9 600 vt.default_red= [VT]
55ff9780
AD
601 Format: <red0>,<red1>,<red2>,...,<red15>
602 Change the default red palette of the console.
603 This is a 16-member array composed of values
604 ranging from 0-255.
605
ecb77fa9
ST
606 vt.default_utf8=
607 [VT]
55ff9780
AD
608 Format=<0|1>
609 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
610 Default is 1, i.e. UTF-8 mode is enabled for all
611 newly opened terminals.
55ff9780 612
1da177e4
LT
613 dhash_entries= [KNL]
614 Set number of hash buckets for dentry cache.
a9913044 615
1da177e4
LT
616 digi= [HW,SERIAL]
617 IO parameters + enable/disable command.
618
619 digiepca= [HW,SERIAL]
620 See drivers/char/README.epca and
621 Documentation/digiepca.txt.
622
95ffa243
YL
623 disable_mtrr_cleanup [X86]
624 enable_mtrr_cleanup [X86]
625 The kernel tries to adjust MTRR layout from continuous
626 to discrete, to make X server driver able to add WB
627 entry later. This parameter enables/disables that.
628
629 mtrr_chunk_size=nn[KMG] [X86]
630 used for mtrr cleanup. It is largest continous chunk
631 that could hold holes aka. UC entries.
632
633 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
634 Used for mtrr cleanup. It is granularity of mtrr block.
635 Default is 1.
636 Large value could prevent small alignment from
637 using up MTRRs.
638
639 mtrr_spare_reg_nr=n [X86]
640 Format: <integer>
641 Range: 0,7 : spare reg number
642 Default : 1
643 Used for mtrr cleanup. It is spare mtrr entries number.
644 Set to 2 or more if your graphical card needs more.
95ffa243 645
093af8d7 646 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
647 By default the kernel will trim any uncacheable
648 memory out of your available memory pool based on
649 MTRR settings. This parameter disables that behavior,
650 possibly causing your machine to run very slowly.
651
1da177e4
LT
652 dmasound= [HW,OSS] Sound subsystem buffers
653
654 dscc4.setup= [NET]
655
656 dtc3181e= [HW,SCSI]
657
0ae53640 658 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
659 earlyprintk=vga
660 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 661 earlyprintk=dbgp
1da177e4 662
a9913044 663 Append ",keep" to not disable it when the real console
1da177e4
LT
664 takes over.
665
5c05917e 666 Only vga or serial or usb debug port at a time.
1da177e4
LT
667
668 Currently only ttyS0 and ttyS1 are supported.
669
670 Interaction with the standard serial driver is not
671 very good.
672
673 The VGA output is eventually overwritten by the real
674 console.
675
676 eata= [HW,SCSI]
677
1da177e4 678 edd= [EDD]
8c4dd606 679 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 680
1da177e4
LT
681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
683
cd4f0ef7 684 elanfreq= [X86-32]
1da177e4 685 See comment before function elanfreq_setup() in
71f77055 686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
687
688 elevator= [IOSCHED]
16ab3adf 689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
692
cd4f0ef7 693 elfcorehdr= [X86-32, X86_64]
a9913044 694 Specifies physical address of start of kernel core
aac04b32
VG
695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
698
699 enforcing [SELINUX] Set initial enforcing status.
700 Format: {"0" | "1"}
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
704 Default value is 0.
705 Value can be changed at runtime via /selinux/enforce.
706
1da177e4
LT
707 es1371= [HW,OSS]
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
a9913044 710
1da177e4
LT
711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
714
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
716 Format: <io>[,<irq>]
717
de1ba09b
AM
718 failslab=
719 fail_page_alloc=
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
724
1da177e4
LT
725 fd_mcs= [HW,SCSI]
726 See header of drivers/scsi/fd_mcs.c.
727
728 fdomain= [HW,SCSI]
729 See header of drivers/scsi/fdomain.c.
730
731 floppy= [HW]
732 See Documentation/floppy.txt.
733
f13ae30e
AC
734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
739
1da177e4
LT
740 gamecon.map[2|3]=
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
745
746 gamma= [HW,DRM]
747
aaf23042
YL
748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
749 Format: off | on
750 default: on
751
1da177e4
LT
752 gdth= [HW,SCSI]
753 See header of drivers/scsi/gdth.c.
754
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
757
1da177e4
LT
758 gvp11= [HW,SCSI]
759
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
a9913044 763 Format: 0 | 1 (for off | on)
1da177e4
LT
764
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
766
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
769
1da177e4
LT
770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
774
54cdfdb4
TG
775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
777 Default: "on"
778
1da177e4
LT
779 hisax= [HW,ISDN]
780 See Documentation/isdn/README.HiSax.
781
b4718e62
AK
782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
e11bfbfc
NP
791 default_hugepagesz=
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
797 if not specified.
1da177e4 798
1da177e4 799 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
800 i8042.dumbkbd [HW] Pretend that controller can only read data from
801 keyboard and cannot control its state
1da177e4
LT
802 (Don't attempt to blink the leds)
803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 804 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
805 i8042.noloop [HW] Disable the AUX Loopback command while probing
806 for the AUX port
1da177e4
LT
807 i8042.nomux [HW] Don't check presence of an active multiplexing
808 controller
809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
810 controllers
811 i8042.panicblink=
812 [HW] Frequency with which keyboard LEDs should blink
813 when kernel panics (default is 0.5 sec)
814 i8042.reset [HW] Reset the controller during init and cleanup
815 i8042.unlock [HW] Unlock (ignore) the keylock
816
817 i810= [HW,DRM]
818
e70c9d5e
DT
819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
820 indicates that the driver is running on unsupported
821 hardware.
1da177e4
LT
822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
823 does not match list of supported models.
824 i8k.power_status
825 [HW] Report power status in /proc/i8k
826 (disabled by default)
827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
828 capability is set.
829
830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
831 See Documentation/mca.txt.
832
833 icn= [HW,ISDN]
834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
835
836 ide= [HW] (E)IDE subsystem
a594eeb1 837 Format: ide=nodma or ide=doubler
1c10e938 838 See Documentation/ide/ide.txt.
1da177e4 839
1da177e4 840 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 841 See Documentation/ide/ide.txt.
1da177e4 842
f039b754 843 idle= [X86]
da5e09a1 844 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
845 Poll forces a polling idle loop that can slightly improves the performance
846 of waking up a idle CPU, but will use a lot of power and make the system
847 run hot. Not recommended.
848 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
849 to not use it because it doesn't save as much power as a normal idle
850 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
851 as idle=poll.
c1e3b377
ZY
852 idle=halt. Halt is forced to be used for CPU idle.
853 In such case C2/C3 won't be used again.
da5e09a1 854 idle=nomwait. Disable mwait for CPU C-states
a9913044 855
594765a7
DC
856 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
857 Claim all unknown PCI IDE storage controllers.
858
79290822
IM
859 ignore_loglevel [KNL]
860 Ignore loglevel setting - this will print /all/
861 kernel messages to the console. Useful for debugging.
862
1da177e4
LT
863 ihash_entries= [KNL]
864 Set number of hash buckets for inode cache.
865
866 in2000= [HW,SCSI]
867 See header of drivers/scsi/in2000.c.
868
869 init= [KNL]
870 Format: <full_path>
871 Run specified binary instead of /sbin/init as init
872 process.
873
874 initcall_debug [KNL] Trace initcalls as they are executed. Useful
875 for working out where the kernel is dying during
876 startup.
877
878 initrd= [BOOT] Specify the location of the initial ramdisk
879
880 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
881 Format: <irq>
882
883 inttest= [IA64]
884
b552da87
PM
885 iommu= [x86]
886 off
887 force
888 noforce
889 biomerge
890 panic
891 nopanic
892 merge
893 nomerge
894 forcesac
895 soft
896
897
ba395927
KA
898 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
899 off
900 Disable intel iommu driver.
901 igfx_off [Default Off]
902 By default, gfx is mapped as normal device. If a gfx
903 device has a dedicated DMAR unit, the DMAR unit is
904 bypassed by not enabling DMAR with this option. In
905 this case, gfx device will use physical address for
906 DMA.
7d3b03ce
KA
907 forcedac [x86_64]
908 With this option iommu will not optimize to look
909 for io virtual address below 32 bit forcing dual
910 address cycle on pci bus for cards supporting greater
911 than 32 bit addressing. The default is to look
912 for translation below 32 bit and if not available
913 then look in the higher range.
5e0d2a6f 914 strict [Default Off]
915 With this option on every unmap_single operation will
916 result in a hardware IOTLB flush operation as opposed
917 to batching them for performance.
ba395927 918
b02aae9c 919 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
920 0x80
921 Standard port 0x80 based delay
922 0xed
923 Alternate port 0xed based delay (needed on some systems)
b02aae9c 924 udelay
6e7c4025
IM
925 Simple two microseconds delay
926 none
927 No delay
b02aae9c 928
1da177e4
LT
929 io7= [HW] IO7 for Marvel based alpha systems
930 See comment before marvel_specify_io7 in
931 arch/alpha/kernel/core_marvel.c.
932
933 ip= [IP_PNP]
6ded55da 934 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
935
936 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
937 See comment before ip2_setup() in
938 drivers/char/ip2/ip2base.c.
1da177e4
LT
939
940 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
941 See header of drivers/scsi/ips.c.
942
72c4a13a
SH
943 ports= [IP_VS_FTP] IPVS ftp helper module
944 Default is 21.
945 Up to 8 (IP_VS_APP_MAX_PORTS) ports
946 may be specified.
947 Format: <port>,<port>....
948
200803df
AC
949 irqfixup [HW]
950 When an interrupt is not handled search all handlers
951 for it. Intended to get systems with badly broken
952 firmware running.
953
954 irqpoll [HW]
955 When an interrupt is not handled search all handlers
956 for it. Also check all handlers each timer
957 interrupt. Intended to get systems with badly broken
958 firmware running.
959
1da177e4 960 isapnp= [ISAPNP]
a9913044 961 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
962
963 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
964 Format:
965 <cpu number>,...,<cpu number>
966 or
967 <cpu number>-<cpu number> (must be a positive range in ascending order)
968 or a mixture
969 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
970 This option can be used to specify one or more CPUs
971 to isolate from the general SMP balancing and scheduling
972 algorithms. The only way to move a process onto or off
973 an "isolated" CPU is via the CPU affinity syscalls.
974 <cpu number> begins at 0 and the maximum value is
975 "number of CPUs in system - 1".
976
977 This option is the preferred way to isolate CPUs. The
a9913044
RD
978 alternative -- manually setting the CPU mask of all
979 tasks in the system -- can cause problems and
980 suboptimal load balancer performance.
1da177e4 981
a9913044 982 iucv= [HW,NET]
1da177e4
LT
983
984 js= [HW,JOY] Analog joystick
985 See Documentation/input/joystick.txt.
986
cd4f0ef7 987 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
988 specifies the amount of memory usable by the kernel
989 for non-movable allocations. The requested amount is
990 spread evenly throughout all nodes in the system. The
991 remaining memory in each node is used for Movable
992 pages. In the event, a node is too small to have both
993 kernelcore and Movable pages, kernelcore pages will
994 take priority and other nodes will have a larger number
995 of kernelcore pages. The Movable zone is used for the
996 allocation of pages that may be reclaimed or moved
997 by the page migration subsystem. This means that
998 HugeTLB pages may not be allocated from this zone.
999 Note that allocations like PTEs-from-HighMem still
1000 use the HighMem zone if it exists, and the Normal
1001 zone if it does not.
1002
cd4f0ef7 1003 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1004 is similar to kernelcore except it specifies the
1005 amount of memory used for migratable allocations.
1006 If both kernelcore and movablecore is specified,
1007 then kernelcore will be at *least* the specified
1008 value but may be more. If movablecore on its own
1009 is specified, the administrator must be careful
1010 that the amount of memory usable for all allocations
1011 is not too small.
1012
1da177e4
LT
1013 keepinitrd [HW,ARM]
1014
cd4f0ef7 1015 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1016 in oops dumps.
1017
6cdf6e06
JW
1018 kgdboc= [HW] kgdb over consoles.
1019 Requires a tty driver that supports console polling.
1020 (only serial suported for now)
1021 Format: <serial_device>[,baud]
1022
9bed90c6
FF
1023 kmac= [MIPS] korina ethernet MAC address.
1024 Configure the RouterBoard 532 series on-chip
1025 Ethernet adapter MAC address.
1026
1da177e4
LT
1027 l2cr= [PPC]
1028
a78bfbfc
RB
1029 l3cr= [PPC]
1030
cd4f0ef7 1031 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1032 disabled it.
1da177e4 1033
cd4f0ef7 1034 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1035 C2 power state.
1036
fcb71f6f
FC
1037 libata.dma= [LIBATA] DMA control
1038 libata.dma=0 Disable all PATA and SATA DMA
1039 libata.dma=1 PATA and SATA Disk DMA only
1040 libata.dma=2 ATAPI (CDROM) DMA only
1041 libata.dma=4 Compact Flash DMA only
1042 Combinations also work, so libata.dma=3 enables DMA
1043 for disks and CDROMs, but not CFs.
1044
78e70c23
DJ
1045 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1046 when set.
1047 Format: <int>
1048
33267325
TH
1049 libata.force= [LIBATA] Force configurations. The format is comma
1050 separated list of "[ID:]VAL" where ID is
1051 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1052 matching port, link or device. Basically, it matches
1053 the ATA ID string printed on console by libata. If
1054 the whole ID part is omitted, the last PORT and DEVICE
1055 values are used. If ID hasn't been specified yet, the
1056 configuration applies to all ports, links and devices.
1057
1058 If only DEVICE is omitted, the parameter applies to
1059 the port and all links and devices behind it. DEVICE
1060 number of 0 either selects the first device or the
1061 first fan-out link behind PMP device. It does not
1062 select the host link. DEVICE number of 15 selects the
1063 host link and device attached to it.
1064
1065 The VAL specifies the configuration to force. As long
1066 as there's no ambiguity shortcut notation is allowed.
1067 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1068 The following configurations can be forced.
1069
1070 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1071 Any ID with matching PORT is used.
1072
1073 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1074
1075 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1076 udma[/][16,25,33,44,66,100,133] notation is also
1077 allowed.
1078
1079 * [no]ncq: Turn on or off NCQ.
1080
05944bdf
TH
1081 * nohrst, nosrst, norst: suppress hard, soft
1082 and both resets.
1083
33267325
TH
1084 If there are multiple matching configurations changing
1085 the same attribute, the last one is used.
1086
1da177e4
LT
1087 load_ramdisk= [RAM] List of ramdisks to load from floppy
1088 See Documentation/ramdisk.txt.
1089
a6b25b67
RD
1090 lockd.nlm_grace_period=P [NFS] Assign grace period.
1091 Format: <integer>
1da177e4 1092
a6b25b67
RD
1093 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1094 Format: <integer>
1095
1096 lockd.nlm_timeout=T [NFS] Assign timeout value.
1097 Format: <integer>
1098
1099 lockd.nlm_udpport=M [NFS] Assign UDP port.
1100 Format: <integer>
1da177e4
LT
1101
1102 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1103 Format: <irq>
1104
1105 loglevel= All Kernel Messages with a loglevel smaller than the
1106 console loglevel will be printed to the console. It can
1107 also be changed with klogd or other programs. The
1108 loglevels are defined as follows:
1109
1110 0 (KERN_EMERG) system is unusable
1111 1 (KERN_ALERT) action must be taken immediately
1112 2 (KERN_CRIT) critical conditions
1113 3 (KERN_ERR) error conditions
1114 4 (KERN_WARNING) warning conditions
1115 5 (KERN_NOTICE) normal but significant condition
1116 6 (KERN_INFO) informational
1117 7 (KERN_DEBUG) debug-level messages
1118
1119 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1120 Format: { n | nk | nM }
1121 n must be a power of two. The default size
1122 is set in the kernel config file.
1da177e4 1123
accaa24c
RD
1124 logo.nologo [FB] Disables display of the built-in Linux logo.
1125 This may be used to provide more screen space for
1126 kernel log messages and is useful when debugging
1127 kernel boot problems.
1128
1da177e4
LT
1129 lp=0 [LP] Specify parallel ports to use, e.g,
1130 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1131 lp=reset first parallel port). 'lp=0' disables the
1132 lp=auto printer driver. 'lp=reset' (which can be
1133 specified in addition to the ports) causes
1134 attached printers to be reset. Using
1135 lp=port1,port2,... specifies the parallel ports
1136 to associate lp devices with, starting with
1137 lp0. A port specification may be 'none' to skip
1138 that lp device, or a parport name such as
1139 'parport0'. Specifying 'lp=auto' instead of a
1140 port specification list means that device IDs
1141 from each port should be examined, to see if
1142 an IEEE 1284-compliant printer is attached; if
1143 so, the driver will manage that printer.
1144 See also header of drivers/char/lp.c.
1145
1146 lpj=n [KNL]
1147 Sets loops_per_jiffy to given constant, thus avoiding
1148 time-consuming boot-time autodetection (up to 250 ms per
1149 CPU). 0 enables autodetection (default). To determine
1150 the correct value for your kernel, boot with normal
1151 autodetection and see what value is printed. Note that
1152 on SMP systems the preset will be applied to all CPUs,
1153 which is likely to cause problems if your CPUs need
1154 significantly divergent settings. An incorrect value
1155 will cause delays in the kernel to be wrong, leading to
1156 unpredictable I/O errors and other breakage. Although
1157 unlikely, in the extreme case this might damage your
1158 hardware.
1159
1160 ltpc= [NET]
1161 Format: <io>,<irq>,<dma>
1162
a9913044
RD
1163 mac5380= [HW,SCSI] Format:
1164 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1165
a9913044
RD
1166 machvec= [IA64] Force the use of a particular machine-vector
1167 (machvec) in a generic kernel.
1168 Example: machvec=hpzx1_swiotlb
1da177e4 1169
a9913044 1170 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1171 be mounted
1172 Format: <1-256>
1173
1174 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1175 should make use of. maxcpus=n : n >= 0 limits the
1176 kernel to using 'n' processors. n=0 is a special case,
1177 it is equivalent to "nosmp", which also disables
1178 the IO APIC.
1da177e4 1179
2b2c3750
BP
1180 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1181 equal to this physical address is ignored.
1182
a9913044 1183 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1184 Should be between 1 and 2^32-1.
1185
1186 max_report_luns=
a9913044 1187 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1188 Should be between 1 and 16384.
1189
1da177e4
LT
1190 mcatest= [IA-64]
1191
cd4f0ef7 1192 mce [X86-32] Machine Check Exception
1da177e4 1193
909dd324
AK
1194 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1195
1da177e4
LT
1196 md= [HW] RAID subsystems devices and level
1197 See Documentation/md.txt.
a9913044 1198
1da177e4
LT
1199 mdacon= [MDA]
1200 Format: <first>,<last>
1201 Specifies range of consoles to be captured by the MDA.
a9913044 1202
1da177e4
LT
1203 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1204 Amount of memory to be used when the kernel is not able
1205 to see the whole system memory or for test.
cd4f0ef7 1206 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1207 address space collisions. Without memmap= PCI devices
1208 could be placed at addresses belonging to unused RAM.
1209
cd4f0ef7 1210 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1211 memory.
1212
cd4f0ef7 1213 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1214 E820 memory map, as specified by the user.
1215 Such memmap=exactmap lines can be constructed based on
1216 BIOS output or other requirements. See the memmap=nn@ss
1217 option description.
1218
1219 memmap=nn[KMG]@ss[KMG]
1220 [KNL] Force usage of a specific region of memory
1221 Region of memory to be used, from ss to ss+nn.
1222
1223 memmap=nn[KMG]#ss[KMG]
1224 [KNL,ACPI] Mark specific memory as ACPI data.
1225 Region of memory to be used, from ss to ss+nn.
1226
1227 memmap=nn[KMG]$ss[KMG]
1228 [KNL,ACPI] Mark specific memory as reserved.
1229 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1230 Example: Exclude memory from 0x18690000-0x1869ffff
1231 memmap=64K$0x18690000
1232 or
1233 memmap=0x10000$0x18690000
1da177e4 1234
9f077871
JF
1235 memory_corruption_check=0/1 [X86]
1236 Some BIOSes seem to corrupt the first 64k of
1237 memory when doing things like suspend/resume.
1238 Setting this option will scan the memory
1239 looking for corruption. Enabling this will
1240 both detect corruption and prevent the kernel
1241 from using the memory being corrupted.
1242 However, its intended as a diagnostic tool; if
1243 repeatable BIOS-originated corruption always
1244 affects the same memory, you can use memmap=
1245 to prevent the kernel from using that memory.
1246
1247 memory_corruption_check_size=size [X86]
1248 By default it checks for corruption in the low
1249 64k, making this memory unavailable for normal
1250 use. Use this parameter to scan for
1251 corruption in more or less memory.
1252
1253 memory_corruption_check_period=seconds [X86]
1254 By default it checks for corruption every 60
1255 seconds. Use this parameter to check at some
1256 other rate. 0 disables periodic checking.
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
6e1cb38a
SS
1455 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1456
af9d1388
SS
1457 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1458 default x2apic cluster mode on platforms
1459 supporting x2apic.
1460
1da177e4
LT
1461 noltlbs [PPC] Do not use large page/tlb entries for kernel
1462 lowmem mapping on PPC40x.
1463
312f1f01
H
1464 nomca [IA-64] Disable machine check abort handling
1465
cd4f0ef7 1466 nomce [X86-32] Machine Check Exception
abe37e5a 1467
83d7384f
AS
1468 nomfgpt [X86-32] Disable Multi-Function General Purpose
1469 Timer usage (for AMD Geode machines).
1470
cd4f0ef7 1471 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1472
cd4f0ef7 1473 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1474 with UP alternatives
1475
1da177e4
LT
1476 noresidual [PPC] Don't use residual data on PReP machines.
1477
a9913044
RD
1478 noresume [SWSUSP] Disables resume and restores original swap
1479 space.
1480
1da177e4
LT
1481 no-scroll [VGA] Disables scrollback.
1482 This is required for the Braillex ib80-piezo Braille
1483 reader made by F.H. Papenmeier (Germany).
1484
1485 nosbagart [IA-64]
1486
cd4f0ef7 1487 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1488
61ec7567
LB
1489 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1490 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1491
97842216
DJ
1492 nosoftlockup [KNL] Disable the soft-lockup detector.
1493
1da177e4
LT
1494 nosync [HW,M68K] Disables sync negotiation for all devices.
1495
cd4f0ef7 1496 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1497
1498 nousb [USB] Disable the USB subsystem
1499
1500 nowb [ARM]
a9913044 1501
a6c75b86
FY
1502 nptcg= [IA64] Override max number of concurrent global TLB
1503 purges which is reported from either PAL_VM_SUMMARY or
1504 SAL PALO.
1505
f0c0b2b8
KH
1506 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1507 one of ['zone', 'node', 'default'] can be specified
1508 This can be set from sysctl after boot.
1509 See Documentation/sysctl/vm.txt for details.
1510
a61c2d78
DJ
1511 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1512
3ef0e1f8
AS
1513 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1514 Rather than timing out after 20 ms if an EC
1515 command is not properly ACKed, override the length
1516 of the timeout. We have interrupts disabled while
1517 waiting for the ACK, so if this is set too high
1518 interrupts *may* be lost!
1519
1da177e4
LT
1520 opl3= [HW,OSS]
1521 Format: <io>
1522
1da177e4
LT
1523 oprofile.timer= [HW]
1524 Use timer interrupt instead of performance counters
1525
1da177e4
LT
1526 osst= [HW,SCSI] SCSI Tape Driver
1527 Format: <buffer_size>,<write_threshold>
1528 See also Documentation/scsi/st.txt.
1529
1530 panic= [KNL] Kernel behaviour on panic
1531 Format: <timeout>
1532
1533 parkbd.port= [HW] Parallel port number the keyboard adapter is
1534 connected to, default is 0.
1535 Format: <parport#>
1536 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1537 0 for XT, 1 for AT (default is AT).
a9913044
RD
1538 Format: <mode>
1539
1540 parport= [HW,PPT] Specify parallel ports. 0 disables.
1541 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1542 Use 'auto' to force the driver to use any
1543 IRQ/DMA settings detected (the default is to
1544 ignore detected IRQ/DMA settings because of
1545 possible conflicts). You can specify the base
1546 address, IRQ, and DMA settings; IRQ and DMA
1547 should be numbers, or 'auto' (for using detected
1548 settings on that particular port), or 'nofifo'
1549 (to avoid using a FIFO even if it is detected).
1550 Parallel ports are assigned in the order they
1551 are specified on the command line, starting
1552 with parport0.
1553
1554 parport_init_mode= [HW,PPT]
1555 Configure VIA parallel port to operate in
1556 a specific mode. This is necessary on Pegasos
1557 computer where firmware has no options for setting
1558 up parallel port mode and sets it to spp.
1559 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1560 Format: [spp|ps2|epp|ecp|ecpepp]
1561
a9913044
RD
1562 pas2= [HW,OSS] Format:
1563 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1564
1da177e4
LT
1565 pas16= [HW,SCSI]
1566 See header of drivers/scsi/pas16.c.
1567
dd287796
AM
1568 pause_on_oops=
1569 Halt all CPUs after the first oops has been printed for
1570 the specified number of seconds. This is to be used if
1571 your oopses keep scrolling off the screen.
1572
1da177e4
LT
1573 pcbit= [HW,ISDN]
1574
1575 pcd. [PARIDE]
1576 See header of drivers/block/paride/pcd.c.
1577 See also Documentation/paride.txt.
1578
a9913044 1579 pci=option[,option...] [PCI] various PCI subsystem options:
cd4f0ef7
AC
1580 off [X86-32] don't probe for the PCI bus
1581 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1582 the hardware directly. Use this if your machine
1583 has a non-standard PCI host bridge.
cd4f0ef7 1584 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1585 hardware access methods are allowed. Use this
1586 if you experience crashes upon bootup and you
1587 suspect they are caused by the BIOS.
cd4f0ef7 1588 conf1 [X86-32] Force use of PCI Configuration
a9913044 1589 Mechanism 1.
cd4f0ef7 1590 conf2 [X86-32] Force use of PCI Configuration
a9913044 1591 Mechanism 2.
7f785763
RD
1592 noaer [PCIE] If the PCIEAER kernel config parameter is
1593 enabled, this kernel boot option can be used to
1594 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1595 nodomains [PCI] Disable support for multiple PCI
1596 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1597 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1598 Configuration
309e57df
MW
1599 nomsi [MSI] If the PCI_MSI kernel config parameter is
1600 enabled, this kernel boot option can be used to
1601 disable the use of MSI interrupts system-wide.
cd4f0ef7 1602 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1603 routing table. These calls are known to be buggy
1604 on several machines and they hang the machine
1605 when used, but on other computers it's the only
1606 way to get the interrupt routing table. Try
1607 this option if the kernel is unable to allocate
1608 IRQs or discover secondary PCI buses on your
1609 motherboard.
cd4f0ef7 1610 rom [X86-32] Assign address space to expansion ROMs.
a9913044
RD
1611 Use with caution as certain devices share
1612 address decoders between ROMs and other
1613 resources.
bb71ad88
GH
1614 norom [X86-32,X86_64] Do not assign address space to
1615 expansion ROMs that do not already have
1616 BIOS assigned address ranges.
cd4f0ef7 1617 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
a9913044
RD
1618 assigned automatically to PCI devices. You can
1619 make the kernel exclude IRQs of your ISA cards
1620 this way.
cd4f0ef7 1621 pirqaddr=0xAAAAA [X86-32] Specify the physical address
a9913044
RD
1622 of the PIRQ table (normally generated
1623 by the BIOS) if it is outside the
1624 F0000h-100000h range.
cd4f0ef7 1625 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
a9913044
RD
1626 useful if the kernel is unable to find your
1627 secondary buses and you want to tell it
1628 explicitly which ones they are.
cd4f0ef7 1629 assign-busses [X86-32] Always assign all PCI bus
a9913044
RD
1630 numbers ourselves, overriding
1631 whatever the firmware may have done.
cd4f0ef7 1632 usepirqmask [X86-32] Honor the possible IRQ mask stored
a9913044
RD
1633 in the BIOS $PIR table. This is needed on
1634 some systems with broken BIOSes, notably
1635 some HP Pavilion N5400 and Omnibook XE3
1636 notebooks. This will have no effect if ACPI
1637 IRQ routing is enabled.
cd4f0ef7 1638 noacpi [X86-32] Do not use ACPI for IRQ routing
a9913044 1639 or for PCI scanning.
62f420f8
GH
1640 use_crs [X86-32] Use _CRS for PCI resource
1641 allocation.
a9913044
RD
1642 routeirq Do IRQ routing for all PCI devices.
1643 This is normally done in pci_enable_device(),
1644 so this option is a temporary workaround
1645 for broken drivers that don't call it.
13a6ddb0
YL
1646 skip_isa_align [X86] do not align io start addr, so can
1647 handle more pci cards
a9913044
RD
1648 firmware [ARM] Do not re-enumerate the bus but instead
1649 just use the configuration from the
1650 bootloader. This is currently used on
1651 IXP2000 systems where the bus has to be
1652 configured a certain way for adjunct CPUs.
0637a70a
AK
1653 noearly [X86] Don't do any early type 1 scanning.
1654 This might help on some broken boards which
1655 machine check when some devices' config space
1656 is read. But various workarounds are disabled
1657 and some IOMMU drivers will not work.
6b4b78fe
MD
1658 bfsort Sort PCI devices into breadth-first order.
1659 This sorting is done to get a device
1660 order compatible with older (<= 2.4) kernels.
1661 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1662 cbiosize=nn[KMG] The fixed amount of bus space which is
1663 reserved for the CardBus bridge's IO window.
1664 The default value is 256 bytes.
1665 cbmemsize=nn[KMG] The fixed amount of bus space which is
1666 reserved for the CardBus bridge's memory
1667 window. The default value is 64 megabytes.
6b4b78fe 1668
1da177e4
LT
1669 pcmv= [HW,PCMCIA] BadgePAD 4
1670
1671 pd. [PARIDE]
1672 See Documentation/paride.txt.
1673
1674 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1675 boot time.
1676 Format: { 0 | 1 }
1677 See arch/parisc/kernel/pdc_chassis.c
1678
1679 pf. [PARIDE]
1680 See Documentation/paride.txt.
1681
1682 pg. [PARIDE]
1683 See Documentation/paride.txt.
1684
1685 pirq= [SMP,APIC] Manual mp-table setup
1686 See Documentation/i386/IO-APIC.txt.
1687
1688 plip= [PPT,NET] Parallel port network link
1689 Format: { parport<nr> | timid | 0 }
1690 See also Documentation/parport.txt.
1691
de32a243
TG
1692 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1693 Override pmtimer IOPort with a hex value.
1694 e.g. pmtmr=0x508
1695
1da177e4
LT
1696 pnpacpi= [ACPI]
1697 { off }
1698
1699 pnpbios= [ISAPNP]
1700 { on | off | curr | res | no-curr | no-res }
1701
1702 pnp_reserve_irq=
1703 [ISAPNP] Exclude IRQs for the autoconfiguration
1704
1705 pnp_reserve_dma=
1706 [ISAPNP] Exclude DMAs for the autoconfiguration
1707
1708 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1709 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1710
1711 pnp_reserve_mem=
a9913044
RD
1712 [ISAPNP] Exclude memory regions for the
1713 autoconfiguration.
1da177e4
LT
1714 Ranges are in pairs (memory base and size).
1715
45807a1d
IM
1716 print-fatal-signals=
1717 [KNL] debug: print fatal signals
1718 print-fatal-signals=1: print segfault info to
1719 the kernel console.
1720 default: off.
1721
e84845c4
RD
1722 printk.time= Show timing data prefixed to each printk message line
1723 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1724
1da177e4 1725 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1726 Format: [schedule,]<number>
1727 Param: "schedule" - profile schedule points.
1728 Param: <number> - step/bucket size as a power of 2 for
1729 statistical time based profiling.
b3da2a73
MG
1730 Param: "sleep" - profile D-state sleeping (millisecs).
1731 Requires CONFIG_SCHEDSTATS
c0fe2e69 1732 Param: "kvm" - profile VM exits.
1da177e4 1733
a9913044 1734 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1735 Limit processor to maximum C-state
1736 max_cstate=9 overrides any DMI blacklist limit.
1737
41c0d868
LB
1738 processor.nocst [HW,ACPI]
1739 Ignore the _CST method to determine C-states,
1740 instead using the legacy FADT method
1741
1da177e4
LT
1742 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1743 before loading.
1744 See Documentation/ramdisk.txt.
1745
a9913044
RD
1746 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1747 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1748 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1749 per second.
a9913044
RD
1750 psmouse.resetafter= [HW,MOUSE]
1751 Try to reset the device after so many bad packets
1da177e4
LT
1752 (0 = never).
1753 psmouse.resolution=
1754 [HW,MOUSE] Set desired mouse resolution, in dpi.
1755 psmouse.smartscroll=
a9913044 1756 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1757 0 = disabled, 1 = enabled (default).
1758
1759 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1760 Format:
1761 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1762
1763 pt. [PARIDE]
1764 See Documentation/paride.txt.
1765
dc8c8587
KS
1766 pty.legacy_count=
1767 [KNL] Number of legacy pty's. Overwrites compiled-in
1768 default number.
1769
7d2c502f 1770 quiet [KNL] Disable most log messages
a9913044 1771
1da177e4
LT
1772 r128= [HW,DRM]
1773
1774 raid= [HW,RAID]
1775 See Documentation/md.txt.
1776
a9913044 1777 ramdisk_blocksize= [RAM]
1da177e4 1778 See Documentation/ramdisk.txt.
a9913044 1779
1da177e4 1780 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1da177e4
LT
1781 See Documentation/ramdisk.txt.
1782
24aaef8d
RD
1783 rcupdate.blimit= [KNL,BOOT]
1784 Set maximum number of finished RCU callbacks to process
1785 in one batch.
21a1ea9e 1786
24aaef8d
RD
1787 rcupdate.qhimark= [KNL,BOOT]
1788 Set threshold of queued
21a1ea9e
DS
1789 RCU callbacks over which batch limiting is disabled.
1790
24aaef8d
RD
1791 rcupdate.qlowmark= [KNL,BOOT]
1792 Set threshold of queued RCU callbacks below which
1793 batch limiting is re-enabled.
21a1ea9e 1794
ffdfc409
OJ
1795 rdinit= [KNL]
1796 Format: <full_path>
1797 Run specified binary instead of /init from the ramdisk,
1798 used for early userspace startup. See initrd.
1799
cd4f0ef7 1800 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1801 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1802 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1803
46b6d94e
PJ
1804 relax_domain_level=
1805 [KNL, SMP] Set scheduler's default relax_domain_level.
1806 See Documentation/cpusets.txt.
1807
1da177e4
LT
1808 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1809
cd4f0ef7 1810 reservetop= [X86-32]
461a9aff
ZA
1811 Format: nn[KMG]
1812 Reserves a hole at the top of the kernel virtual
1813 address space.
1814
7e96287d
VG
1815 reset_devices [KNL] Force drivers to reset the underlying device
1816 during initialization.
1817
a9913044
RD
1818 resume= [SWSUSP]
1819 Specify the partition device for software suspend
1da177e4 1820
ecbd0da1
RW
1821 resume_offset= [SWSUSP]
1822 Specify the offset from the beginning of the partition
1823 given by "resume=" at which the swap header is located,
1824 in <PAGE_SIZE> units (needed only for swap files).
1825 See Documentation/power/swsusp-and-swap-files.txt
1826
0a7b35cb
MN
1827 retain_initrd [RAM] Keep initrd memory after extraction
1828
1da177e4
LT
1829 rhash_entries= [KNL,NET]
1830 Set number of hash buckets for route cache
1831
1832 riscom8= [HW,SERIAL]
1833 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1834
1835 ro [KNL] Mount root device read-only on boot
1836
1837 root= [KNL] Root filesystem
1838
1839 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1840 mount the root filesystem
1841
1842 rootflags= [KNL] Set root filesystem mount option string
1843
1844 rootfstype= [KNL] Set root filesystem type
1845
cc1ed754
PO
1846 rootwait [KNL] Wait (indefinitely) for root device to show up.
1847 Useful for devices that are detected asynchronously
1848 (e.g. USB and MMC devices).
1849
20510f2f
JM
1850 root_plug.vendor_id=
1851 [ROOTPLUG] Override the default vendor ID
1852
1853 root_plug.product_id=
1854 [ROOTPLUG] Override the default product ID
1855
1856 root_plug.debug=
1857 [ROOTPLUG] Enable debugging output
1858
1da177e4
LT
1859 rw [KNL] Mount root device read-write on boot
1860
1861 S [KNL] Run init in single mode
1862
1863 sa1100ir [NET]
1864 See drivers/net/irda/sa1100_ir.c.
1865
1da177e4 1866 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1867
1da177e4
LT
1868 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1869 Format: <io>[,<timeout>[,<isapnp>]]
1870
1871 scsi_debug_*= [SCSI]
1872 See drivers/scsi/scsi_debug.c.
1873
1874 scsi_default_dev_flags=
1875 [SCSI] SCSI default device flags
1876 Format: <integer>
1877
1878 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1879 Format: <vendor>:<model>:<flags>
1880 (flags are integer value)
1881
6af6632a
RD
1882 scsi_logging_level= [SCSI] a bit mask of logging levels
1883 See drivers/scsi/scsi_logging.h for bits. Also
1884 settable via sysctl at dev.scsi.logging_level
1885 (/proc/sys/dev/scsi/logging_level).
1886 There is also a nice 'scsi_logging_level' script in the
1887 S390-tools package, available for download at
1888 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1889
3e082a91
MW
1890 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1891 discovered. async scans them in kernel threads,
1892 allowing boot to proceed. none ignores them, expecting
1893 user space to do the scan.
1894
1da177e4
LT
1895 selinux [SELINUX] Disable or enable SELinux at boot time.
1896 Format: { "0" | "1" }
1897 See security/selinux/Kconfig help text.
1898 0 -- disable.
1899 1 -- enable.
1900 Default value is set via kernel config option.
1901 If enabled at boot time, /selinux/disable can be used
1902 later to disable prior to initial policy load.
1903
4e5ab4cb
JM
1904 selinux_compat_net =
1905 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1906 Format: { "0" | "1" }
1907 0 -- use new secmark-based packet controls
1908 1 -- use legacy packet controls
1909 Default value is 0 (preferred).
1910 Value can be changed at runtime via
1911 /selinux/compat_net.
4e5ab4cb 1912
cd4f0ef7 1913 serialnumber [BUGS=X86-32]
1da177e4 1914
1da177e4
LT
1915 shapers= [NET]
1916 Maximal number of shapers.
a9913044 1917
b05f78f5
YL
1918 show_msr= [x86] show boot-time MSR settings
1919 Format: { <integer> }
1920 Show boot-time (BIOS-initialized) MSR settings.
1921 The parameter means the number of CPUs to show,
1922 for example 1 means boot CPU only.
1923
1da177e4
LT
1924 sim710= [SCSI,HW]
1925 See header of drivers/scsi/sim710.c.
1926
1927 simeth= [IA-64]
1928 simscsi=
a9913044 1929
1da177e4
LT
1930 slram= [HW,MTD]
1931
f0630fff
CL
1932 slub_debug[=options[,slabs]] [MM, SLUB]
1933 Enabling slub_debug allows one to determine the
1934 culprit if slab objects become corrupted. Enabling
1935 slub_debug can create guard zones around objects and
1936 may poison objects when not in use. Also tracks the
1937 last alloc / free. For more information see
1938 Documentation/vm/slub.txt.
c1aee215
CL
1939
1940 slub_max_order= [MM, SLUB]
f0630fff
CL
1941 Determines the maximum allowed order for slabs.
1942 A high setting may cause OOMs due to memory
1943 fragmentation. For more information see
1944 Documentation/vm/slub.txt.
c1aee215
CL
1945
1946 slub_min_objects= [MM, SLUB]
f0630fff
CL
1947 The minimum number of objects per slab. SLUB will
1948 increase the slab order up to slub_max_order to
1949 generate a sufficiently large slab able to contain
1950 the number of objects indicated. The higher the number
1951 of objects the smaller the overhead of tracking slabs
1952 and the less frequently locks need to be acquired.
c1aee215
CL
1953 For more information see Documentation/vm/slub.txt.
1954
1955 slub_min_order= [MM, SLUB]
1956 Determines the mininum page order for slabs. Must be
f0630fff 1957 lower than slub_max_order.
c1aee215
CL
1958 For more information see Documentation/vm/slub.txt.
1959
1960 slub_nomerge [MM, SLUB]
f0630fff 1961 Disable merging of slabs with similar size. May be
c1aee215 1962 necessary if there is some reason to distinguish
f0630fff
CL
1963 allocs to different slabs. Debug options disable
1964 merging on their own.
c1aee215
CL
1965 For more information see Documentation/vm/slub.txt.
1966
1da177e4
LT
1967 smart2= [HW]
1968 Format: <io1>[,<io2>[,...,<io8>]]
1969
cd4f0ef7 1970 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
1971 attempt to substitute SMP alternatives once at boot.
1972
d0d4f69b
BH
1973 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1974 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1975 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1976 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1977 smsc-ircc2.ircc_irq= [HW] IRQ line
1978 smsc-ircc2.ircc_dma= [HW] DMA channel
1979 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1980 0: Toshiba Satellite 1800 (GP data pin select)
1981 1: Fast pin select (default)
1982 2: ATC IRMode
1983
1da177e4
LT
1984 snd-ad1816a= [HW,ALSA]
1985
1986 snd-ad1848= [HW,ALSA]
1987
1988 snd-ali5451= [HW,ALSA]
1989
1990 snd-als100= [HW,ALSA]
1991
1992 snd-als4000= [HW,ALSA]
1993
1994 snd-azt2320= [HW,ALSA]
1995
1996 snd-cmi8330= [HW,ALSA]
1997
1998 snd-cmipci= [HW,ALSA]
1999
2000 snd-cs4231= [HW,ALSA]
2001
2002 snd-cs4232= [HW,ALSA]
2003
2004 snd-cs4236= [HW,ALSA]
2005
2006 snd-cs4281= [HW,ALSA]
2007
2008 snd-cs46xx= [HW,ALSA]
2009
2010 snd-dt019x= [HW,ALSA]
2011
2012 snd-dummy= [HW,ALSA]
2013
2014 snd-emu10k1= [HW,ALSA]
2015
2016 snd-ens1370= [HW,ALSA]
2017
2018 snd-ens1371= [HW,ALSA]
2019
2020 snd-es968= [HW,ALSA]
2021
2022 snd-es1688= [HW,ALSA]
2023
2024 snd-es18xx= [HW,ALSA]
2025
2026 snd-es1938= [HW,ALSA]
2027
2028 snd-es1968= [HW,ALSA]
2029
2030 snd-fm801= [HW,ALSA]
2031
2032 snd-gusclassic= [HW,ALSA]
2033
2034 snd-gusextreme= [HW,ALSA]
2035
2036 snd-gusmax= [HW,ALSA]
2037
2038 snd-hdsp= [HW,ALSA]
2039
2040 snd-ice1712= [HW,ALSA]
2041
2042 snd-intel8x0= [HW,ALSA]
2043
2044 snd-interwave= [HW,ALSA]
2045
2046 snd-interwave-stb=
2047 [HW,ALSA]
2048
2049 snd-korg1212= [HW,ALSA]
2050
2051 snd-maestro3= [HW,ALSA]
2052
2053 snd-mpu401= [HW,ALSA]
2054
2055 snd-mtpav= [HW,ALSA]
2056
2057 snd-nm256= [HW,ALSA]
2058
2059 snd-opl3sa2= [HW,ALSA]
2060
2061 snd-opti92x-ad1848=
2062 [HW,ALSA]
2063
2064 snd-opti92x-cs4231=
2065 [HW,ALSA]
2066
2067 snd-opti93x= [HW,ALSA]
2068
2069 snd-pmac= [HW,ALSA]
2070
2071 snd-rme32= [HW,ALSA]
2072
2073 snd-rme96= [HW,ALSA]
2074
2075 snd-rme9652= [HW,ALSA]
2076
2077 snd-sb8= [HW,ALSA]
2078
2079 snd-sb16= [HW,ALSA]
2080
2081 snd-sbawe= [HW,ALSA]
2082
2083 snd-serial= [HW,ALSA]
2084
2085 snd-sgalaxy= [HW,ALSA]
2086
2087 snd-sonicvibes= [HW,ALSA]
2088
2089 snd-sun-amd7930=
2090 [HW,ALSA]
2091
2092 snd-sun-cs4231= [HW,ALSA]
2093
2094 snd-trident= [HW,ALSA]
2095
2096 snd-usb-audio= [HW,ALSA,USB]
2097
2098 snd-via82xx= [HW,ALSA]
2099
2100 snd-virmidi= [HW,ALSA]
2101
2102 snd-wavefront= [HW,ALSA]
2103
2104 snd-ymfpci= [HW,ALSA]
a9913044 2105
9c44bc03
IM
2106 softlockup_panic=
2107 [KNL] Should the soft-lockup detector generate panics.
2108
1da177e4
LT
2109 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2110 See Documentation/sonypi.txt
2111
2112 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2113 See Documentation/specialix.txt.
2114
2115 spia_io_base= [HW,MTD]
2116 spia_fio_base=
2117 spia_pedr=
2118 spia_peddr=
2119
2120 sscape= [HW,OSS]
2121 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2122
1da177e4
LT
2123 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2124 See Documentation/scsi/st.txt.
2125
1da177e4
LT
2126 sti= [PARISC,HW]
2127 Format: <num>
2128 Set the STI (builtin display/keyboard on the HP-PARISC
2129 machines) console (graphic card) which should be used
2130 as the initial boot-console.
2131 See also comment in drivers/video/console/sticore.c.
2132
2133 sti_font= [HW]
2134 See comment in drivers/video/console/sticore.c.
2135
2136 stifb= [HW]
2137 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2138
42a7fc4a
GB
2139 sunrpc.pool_mode=
2140 [NFS]
2141 Control how the NFS server code allocates CPUs to
2142 service thread pools. Depending on how many NICs
2143 you have and where their interrupts are bound, this
2144 option will affect which CPUs will do NFS serving.
2145 Note: this parameter cannot be changed while the
2146 NFS server is running.
2147
2148 auto the server chooses an appropriate mode
2149 automatically using heuristics
2150 global a single global pool contains all CPUs
2151 percpu one pool for each CPU
2152 pernode one pool for each NUMA node (equivalent
2153 to global on non-NUMA machines)
2154
1da177e4 2155 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2156
1da177e4
LT
2157 switches= [HW,M68k]
2158
2159 sym53c416= [HW,SCSI]
2160 See header of drivers/scsi/sym53c416.c.
2161
5d6f647f
IM
2162 sysrq_always_enabled
2163 [KNL]
2164 Ignore sysrq setting - this boot parameter will
2165 neutralize any effect of /proc/sys/kernel/sysrq.
2166 Useful for debugging.
2167
1da177e4
LT
2168 t128= [HW,SCSI]
2169 See header of drivers/scsi/t128.c.
2170
2171 tdfx= [HW,DRM]
2172
77437fd4
DB
2173 test_suspend= [SUSPEND]
2174 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2175 standby suspend) as the system sleep state to briefly
2176 enter during system startup. The system is woken from
2177 this state using a wakeup-capable RTC alarm.
2178
1da177e4
LT
2179 thash_entries= [KNL,NET]
2180 Set number of hash buckets for TCP connection
2181
f8707ec9
LB
2182 thermal.act= [HW,ACPI]
2183 -1: disable all active trip points in all thermal zones
2184 <degrees C>: override all lowest active trip points
2185
c52a7419
LB
2186 thermal.crt= [HW,ACPI]
2187 -1: disable all critical trip points in all thermal zones
2188 <degrees C>: lower all critical trip points
2189
f5487145
LB
2190 thermal.nocrt= [HW,ACPI]
2191 Set to disable actions on ACPI thermal zone
2192 critical and hot trip points.
2193
72b33ef8
LB
2194 thermal.off= [HW,ACPI]
2195 1: disable ACPI thermal control
2196
a70cdc52
LB
2197 thermal.psv= [HW,ACPI]
2198 -1: disable all passive trip points
2199 <degrees C>: override all passive trip points to this value
2200
730ff34d
LB
2201 thermal.tzp= [HW,ACPI]
2202 Specify global default ACPI thermal zone polling rate
2203 <deci-seconds>: poll all this frequency
2204 0: no polling (default)
2205
1da177e4
LT
2206 tmscsim= [HW,SCSI]
2207 See comment before function dc390_setup() in
2208 drivers/scsi/tmscsim.c.
2209
2210 tp720= [HW,PS2]
2211
2212 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2213 Format:
2214 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2215
a9913044
RD
2216 turbografx.map[2|3]= [HW,JOY]
2217 TurboGraFX parallel port interface
2218 Format:
2219 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2220 See also Documentation/input/joystick-parport.txt
2221
2222 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2223 See header of drivers/scsi/u14-34f.c.
2224
2225 uart401= [HW,OSS]
2226 Format: <io>,<irq>
2227
2228 uart6850= [HW,OSS]
2229 Format: <io>,<irq>
2230
5f8364b7
AS
2231 uhci-hcd.ignore_oc=
2232 [USB] Ignore overcurrent events (default N).
2233 Some badly-designed motherboards generate lots of
2234 bogus events, for ports that aren't wired to
2235 anything. Set this parameter to avoid log spamming.
2236 Note that genuine overcurrent events won't be
2237 reported either.
2238
e3a61b0a
SA
2239 unknown_nmi_panic
2240 [X86-32,X86-64]
2241 Set unknown_nmi_panic=1 early on boot.
2242
b5e795f8
AS
2243 usbcore.autosuspend=
2244 [USB] The autosuspend time delay (in seconds) used
2245 for newly-detected USB devices (default 2). This
2246 is the time required before an idle device will be
2247 autosuspended. Devices for which the delay is set
eaafbc3a 2248 to a negative value won't be autosuspended at all.
b5e795f8 2249
1da177e4
LT
2250 usbhid.mousepoll=
2251 [USBHID] The interval which mice are to be polled at.
a9913044 2252
200001eb
PJ
2253 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2254 kernel's map of available physical RAM.
2255
cd4f0ef7 2256 vdso= [X86-32,SH,x86-64]
1dbf527c 2257 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2258 vdso=1: enable VDSO (default)
2259 vdso=0: disable VDSO mapping
2260
af65d648
RM
2261 vdso32= [X86-32,X86-64]
2262 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2263 vdso32=1: enable 32-bit VDSO (default)
2264 vdso32=0: disable 32-bit VDSO mapping
2265
d080d397
YI
2266 vector= [IA-64,SMP]
2267 vector=percpu: enable percpu vector domain
2268
1da177e4
LT
2269 video= [FB] Frame buffer configuration
2270 See Documentation/fb/modedb.txt.
2271
cd4f0ef7 2272 vga= [BOOT,X86-32] Select a particular video mode
a9913044
RD
2273 See Documentation/i386/boot.txt and
2274 Documentation/svga.txt.
1da177e4
LT
2275 Use vga=ask for menu.
2276 This is actually a boot loader parameter; the value is
2277 passed to the kernel using a special protocol.
2278
a9913044 2279 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2280 size of <nn>. This can be used to increase the
2281 minimum size (128MB on x86). It can also be used to
2282 decrease the size and leave more room for directly
2283 mapped kernel RAM.
2284
585c3047
PO
2285 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2286 Format: <command>
1da177e4 2287
585c3047
PO
2288 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2289 Format: <command>
2290
2291 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2292 Format: <command>
a9913044 2293
1da177e4
LT
2294 waveartist= [HW,OSS]
2295 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2296
1da177e4
LT
2297 wd33c93= [HW,SCSI]
2298 See header of drivers/scsi/wd33c93.c.
2299
2300 wd7000= [HW,SCSI]
2301 See header of drivers/scsi/wd7000.c.
2302
2303 wdt= [WDT] Watchdog
8dfe9c21 2304 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2305
2306 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2307 xd_geo= See header of drivers/block/xd.c.
2308
2309 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2310 Format:
2311 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2312
a62eaf15
AK
2313 norandmaps Don't use address space randomization
2314 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2315
a9913044 2316______________________________________________________________________
1da177e4
LT
2317
2318TODO:
2319
2320 Add documentation for ALSA options.
2321 Add more DRM drivers.