]> git.proxmox.com Git - mirror_ubuntu-hirsute-kernel.git/blame - Documentation/kernel-parameters.txt
i386: fix argument signedness warnings
[mirror_ubuntu-hirsute-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.
37 AX25 Appropriate AX.25 support is enabled.
0ae53640 38 BLACKFIN Blackfin architecture is enabled.
a9913044 39 DRM Direct Rendering Management support is enabled.
1da177e4
LT
40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
1da177e4
LT
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
1da177e4
LT
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
11ef697b 51 LIBATA Libata driver is enabled
1da177e4
LT
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
309e57df 60 MSI Message Signaled Interrupts (PCI).
c8facbb6 61 MTD MTD (Memory Technology Device) support is enabled.
1da177e4
LT
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
734efb46 64 GENERIC_TIME The generic timeofday code is enabled.
1da177e4
LT
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
c8facbb6
RD
67 PV_OPS A paravirtualized kernel is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
1da177e4
LT
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
7f785763 71 PCIE PCI Express support is enabled.
1da177e4
LT
72 PCMCIA The PCMCIA subsystem is enabled.
73 PNP Plug & Play support is enabled.
74 PPC PowerPC architecture is enabled.
75 PPT Parallel port support is enabled.
76 PS2 Appropriate PS/2 support is enabled.
77 RAM RAM disk support is enabled.
20510f2f 78 ROOTPLUG The example Root Plug LSM is enabled.
1da177e4
LT
79 S390 S390 architecture is enabled.
80 SCSI Appropriate SCSI support is enabled.
81 A lot of drivers has their options described inside of
82 Documentation/scsi/.
20510f2f 83 SECURITY Different security models are enabled.
1da177e4
LT
84 SELINUX SELinux support is enabled.
85 SERIAL Serial support is enabled.
e523d93c 86 SH SuperH architecture is enabled.
1da177e4
LT
87 SMP The kernel is an SMP kernel.
88 SPARC Sparc architecture is enabled.
a9913044 89 SWSUSP Software suspend is enabled.
1da177e4
LT
90 TS Appropriate touchscreen support is enabled.
91 USB USB support is enabled.
92 USBHID USB Human Interface Device support is enabled.
93 V4L Video For Linux support is enabled.
94 VGA The VGA console has been enabled.
95 VT Virtual terminal support is enabled.
96 WDT Watchdog support is enabled.
97 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 98 X86-32 X86-32, aka i386 architecture is enabled.
1da177e4
LT
99 X86-64 X86-64 architecture is enabled.
100 More X86-64 boot options can be found in
101 Documentation/x86_64/boot-options.txt .
102
103In addition, the following text indicates that the option:
104
105 BUGS= Relates to possible processor bugs on the said processor.
106 KNL Is a kernel start-up parameter.
107 BOOT Is a boot loader parameter.
108
109Parameters denoted with BOOT are actually interpreted by the boot
110loader, and have no meaning to the kernel directly.
111Do not modify the syntax of boot loader parameters without extreme
112need or coordination with <Documentation/i386/boot.txt>.
113
5558870b
KW
114There are also arch-specific kernel-parameters not documented here.
115See for example <Documentation/x86_64/boot-options.txt>.
116
1da177e4
LT
117Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
118a trailing = on the name of any parameter states that that parameter will
119be entered as an environment variable, whereas its absence indicates that
120it will appear as a kernel argument readable via /proc/cmdline by programs
121running once the system is up.
122
9c4751fd 123The number of kernel parameters is not limited, but the length of the
124complete command line (parameters including spaces etc.) is limited to
125a fixed number of characters. This limit depends on the architecture
126and is between 256 and 4096 characters. It is defined in the file
127./include/asm/setup.h as COMMAND_LINE_SIZE.
128
129
03d926f8
BW
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
a9913044 132 Format: { force | off | ht | strict | noirq }
1da177e4
LT
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
a9913044 137 strict -- Be less tolerant of platforms that are not
1da177e4
LT
138 strictly ACPI specification compliant.
139
140 See also Documentation/pm.txt, pci=noacpi
141
a1fdcc0d
LB
142 acpi_apic_instance= [ACPI, IOAPIC]
143 Format: <int>
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
4e381a4f 146 default: 0
a1fdcc0d 147
1da177e4
LT
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
a9913044 151
1da177e4 152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 153 Format: { level | edge | high | low }
1da177e4 154
a9913044
RD
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
157 default in APIC mode
1da177e4 158
a9913044
RD
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
161 default in PIC mode
1da177e4 162
a9913044
RD
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 use by PCI
1da177e4
LT
165 Format: <irq>,<irq>...
166
a9913044 167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
1da177e4
LT
168 Format: <irq>,<irq>...
169
67effe8f
LB
170 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
171
a1f9e65e
LB
172 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
173 Format: To spoof as Windows 98: ="Microsoft Windows"
174
ae00d812
LB
175 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
176 acpi_osi="string1" # add string1 -- only one string
177 acpi_osi="!string2" # remove built-in string2
178 acpi_osi= # disable all strings
1da177e4
LT
179
180 acpi_serialize [HW,ACPI] force serialization of AML methods
181
182 acpi_skip_timer_override [HW,ACPI]
183 Recognize and ignore IRQ0/pin2 Interrupt Override.
184 For broken nForce2 BIOS resulting in XT-PIC timer.
fa18f477
AK
185 acpi_use_timer_override [HW,ACPI}
186 Use timer override. For some broken Nvidia NF5 boards
187 that require a timer override, but don't have
188 HPET
1da177e4 189
f989106c 190 acpi.debug_layer= [HW,ACPI]
1da177e4 191 Format: <int>
a9913044 192 Each bit of the <int> indicates an ACPI debug layer,
1da177e4
LT
193 1: enable, 0: disable. It is useful for boot time
194 debugging. After system has booted up, it can be set
f989106c
ZR
195 via /sys/module/acpi/parameters/debug_layer.
196 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
197 Available bits (add the numbers together) to enable debug output
198 for specific parts of the ACPI subsystem:
199 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
200 0x10 namespace 0x20 parser 0x40 dispatcher
201 0x80 executer 0x100 resources 0x200 acpica debugger
202 0x400 os services 0x800 acpica disassembler.
203 The number can be in decimal or prefixed with 0x in hex.
204 Warning: Many of these options can produce a lot of
205 output and make your system unusable. Be very careful.
206
207 acpi.debug_level= [HW,ACPI]
1da177e4 208 Format: <int>
a9913044 209 Each bit of the <int> indicates an ACPI debug level,
1da177e4
LT
210 1: enable, 0: disable. It is useful for boot time
211 debugging. After system has booted up, it can be set
f989106c
ZR
212 via /sys/module/acpi/parameters/debug_level.
213 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
214 Available bits (add the numbers together) to enable different
215 debug output levels of the ACPI subsystem:
216 0x01 error 0x02 warn 0x04 init 0x08 debug object
217 0x10 info 0x20 init names 0x40 parse 0x80 load
218 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
219 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
220 0x10000 resources 0x20000 user requests 0x40000 package.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
224
1da177e4
LT
225
226 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
227
cd4f0ef7 228 acpi_pm_good [X86-32,X86-64]
5d0cf410
JS
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
c99c108a
CE
233 agp= [AGP]
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
238
66759a01
CE
239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
a9913044
RD
241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
66759a01
CE
243 The kernel tries to set a reasonable default.
244
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
248
1da177e4
LT
249 ad1848= [HW,OSS]
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
251
1da177e4
LT
252 advansys= [HW,SCSI]
253 See header of drivers/scsi/advansys.c.
254
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
257
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
a9913044 261
1da177e4
LT
262 aha152x= [HW,SCSI]
263 See Documentation/scsi/aha152x.txt.
264
265 aha1542= [HW,SCSI]
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
267
268 aic7xxx= [HW,SCSI]
269 See Documentation/scsi/aic7xxx.txt.
270
271 aic79xx= [HW,SCSI]
272 See Documentation/scsi/aic79xx.txt.
273
1da177e4
LT
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
276 Format: <a>,<b>
277 See also Documentation/kernel/input/joystick.txt
278
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
283
a9913044
RD
284 apc= [HW,SPARC]
285 Power management functions (SPARCstation-4/5 + deriv.)
1da177e4
LT
286 Format: noidle
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
290
c8facbb6
RD
291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
1da177e4
LT
293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
a9913044 296
1da177e4
LT
297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
299
300 applicom= [HW]
301 Format: <mem>,<irq>
a9913044 302
1da177e4
LT
303 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
304 Format: <io>,<irq>,<nodeID>
305
306 ataflop= [HW,M68k]
307
308 atarimouse= [HW,MOUSE] Atari Mouse
309
310 atascsi= [HW,SCSI] Atari SCSI
311
312 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
313 EzKey and similar keyboards
314
315 atkbd.reset= [HW] Reset keyboard during initialization
316
a9913044
RD
317 atkbd.set= [HW] Select keyboard code set
318 Format: <int> (2 = AT (default), 3 = PS/2)
1da177e4
LT
319
320 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
321 keyboards
322
323 atkbd.softraw= [HW] Choose between synthetic and real raw mode
324 Format: <bool> (0 = real, 1 = synthetic (default))
a9913044
RD
325
326 atkbd.softrepeat= [HW]
327 Use software keyboard repeat
1da177e4
LT
328
329 autotest [IA64]
330
1da177e4
LT
331 baycom_epp= [HW,AX25]
332 Format: <io>,<mode>
a9913044 333
1da177e4
LT
334 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
335 Format: <io>,<mode>
336 See header of drivers/net/hamradio/baycom_par.c.
337
a9913044
RD
338 baycom_ser_fdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
1da177e4
LT
340 Format: <io>,<irq>,<mode>[,<baud>]
341 See header of drivers/net/hamradio/baycom_ser_fdx.c.
342
a9913044
RD
343 baycom_ser_hdx= [HW,AX25]
344 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
1da177e4
LT
345 Format: <io>,<irq>,<mode>
346 See header of drivers/net/hamradio/baycom_ser_hdx.c.
347
348 blkmtd_device= [HW,MTD]
349 blkmtd_erasesz=
350 blkmtd_ro=
351 blkmtd_bs=
352 blkmtd_count=
353
bfe8df3d
RD
354 boot_delay= Milliseconds to delay each printk during boot.
355 Values larger than 10 seconds (10000) are changed to
356 no delay (0).
357 Format: integer
358
1da177e4 359 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
a9913044
RD
360 bttv.radio= Most important insmod options are available as
361 kernel args too.
1da177e4
LT
362 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
363 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
364
365 BusLogic= [HW,SCSI]
366 See drivers/scsi/BusLogic.c, comment before function
367 BusLogic_ParseDriverOptions().
368
369 c101= [NET] Moxa C101 synchronous serial card
370
cd4f0ef7 371 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
1da177e4
LT
372 Sometimes CPU hardware bugs make them report the cache
373 size incorrectly. The kernel will attempt work arounds
374 to fix known problems, but for some CPUs it is not
375 possible to determine what the correct size should be.
376 This option provides an override for these situations.
377
20510f2f
JM
378 capability.disable=
379 [SECURITY] Disable capabilities. This would normally
380 be used only if an alternative security model is to be
381 configured. Potentially dangerous and should only be
382 used if you are entirely sure of the consequences.
383
1da177e4
LT
384 chandev= [HW,NET] Generic channel device initialisation
385
386 checkreqprot [SELINUX] Set initial checkreqprot flag value.
387 Format: { "0" | "1" }
388 See security/selinux/Kconfig help text.
a9913044
RD
389 0 -- check protection applied by kernel (includes
390 any implied execute protection).
1da177e4
LT
391 1 -- check protection requested by application.
392 Default value is set via a kernel config option.
a9913044
RD
393 Value can be changed at runtime via
394 /selinux/checkreqprot.
395
cd4f0ef7 396 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 397 [Deprecated]
3f6dee9b 398 Forces specified clocksource (if available) to be used
734efb46 399 when calculating gettimeofday(). If specified
3f6dee9b 400 clocksource is not available, it defaults to PIT.
1da177e4
LT
401 Format: { pit | tsc | cyclone | pmtmr }
402
3d6ac984
RD
403 clocksource= [GENERIC_TIME] Override the default clocksource
404 Format: <string>
405 Override the default clocksource and use the clocksource
406 with the name specified.
407 Some clocksource names to choose from, depending on
408 the platform:
409 [all] jiffies (this is the base, fallback clocksource)
410 [ACPI] acpi_pm
411 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
412 pxa_timer,timer3,32k_counter,timer0_1
413 [AVR32] avr32
cd4f0ef7 414 [X86-32] pit,hpet,tsc,vmi-timer;
3d6ac984
RD
415 scx200_hrt on Geode; cyclone on IBM x440
416 [MIPS] MIPS
417 [PARISC] cr16
418 [S390] tod
419 [SH] SuperH
420 [SPARC64] tick
421 [X86-64] hpet,tsc
422
86c41837
CE
423 code_bytes [IA32] How many bytes of object code to print in an
424 oops report.
425 Range: 0 - 8192
426 Default: 64
427
f9262c12
AK
428 disable_8254_timer
429 enable_8254_timer
430 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
431 over the 8254 in addition to over the IO-APIC. The
432 kernel tries to set a sensible default.
433
cd4f0ef7 434 hpet= [X86-32,HPET] option to disable HPET and use PIT.
1da177e4
LT
435 Format: disable
436
1da177e4 437 com20020= [HW,NET] ARCnet - COM20020 chipset
a9913044
RD
438 Format:
439 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
1da177e4
LT
440
441 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
442 Format: <io>[,<irq>]
443
a9913044
RD
444 com90xx= [HW,NET]
445 ARCnet - COM90xx chipset (memory-mapped buffers)
1da177e4
LT
446 Format: <io>[,<irq>[,<memstart>]]
447
448 condev= [HW,S390] console device
449 conmode=
a9913044 450
1da177e4
LT
451 console= [KNL] Output console device and options.
452
453 tty<n> Use the virtual console device <n>.
454
455 ttyS<n>[,options]
f1a1c2dc 456 ttyUSB0[,options]
1da177e4 457 Use the specified serial port. The options are of
f1a1c2dc
RD
458 the form "bbbbpnf", where "bbbb" is the baud rate,
459 "p" is parity ("n", "o", or "e"), "n" is number of
460 bits, and "f" is flow control ("r" for RTS or
461 omit it). Default is "9600n8".
462
463 See Documentation/serial-console.txt for more
464 information. See
465 Documentation/networking/netconsole.txt for an
466 alternative.
1da177e4 467
18a8bd94
YL
468 uart[8250],io,<addr>[,options]
469 uart[8250],mmio,<addr>[,options]
1da177e4
LT
470 Start an early, polled-mode console on the 8250/16550
471 UART at the specified I/O port or MMIO address,
472 switching to the matching ttyS device later. The
473 options are the same as for ttyS, above.
474
18a8bd94
YL
475 earlycon= [KNL] Output early console device and options.
476 uart[8250],io,<addr>[,options]
477 uart[8250],mmio,<addr>[,options]
478 Start an early, polled-mode console on the 8250/16550
479 UART at the specified I/O port or MMIO address.
480 The options are the same as for ttyS, above.
481
1da177e4 482 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
483 Format:
484 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 485
dc009d92
EB
486 crashkernel=nn[KMG]@ss[KMG]
487 [KNL] Reserve a chunk of physical memory to
488 hold a kernel to switch to with kexec on panic.
489
1da177e4
LT
490 cs4232= [HW,OSS]
491 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
492
493 cs89x0_dma= [HW,NET]
494 Format: <dma>
495
496 cs89x0_media= [HW,NET]
497 Format: { rj45 | aui | bnc }
a9913044 498
1da177e4 499 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
a9913044
RD
500
501 dasd= [HW,NET]
1da177e4
LT
502 See header of drivers/s390/block/dasd_devmap.c.
503
504 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
505 (one device per port)
506 Format: <port#>,<type>
507 See also Documentation/input/joystick-parport.txt
508
509 debug [KNL] Enable kernel debugging (events log level).
510
cae2ed9a
IM
511 debug_locks_verbose=
512 [KNL] verbose self-tests
513 Format=<0|1>
514 Print debugging info while doing the locking API
515 self-tests.
516 We default to 0 (no extra messages), setting it to
517 1 will print _a lot_ more information - normally
518 only useful to kernel developers.
519
1da177e4
LT
520 decnet= [HW,NET]
521 Format: <area>[,<node>]
522 See also Documentation/networking/decnet.txt.
523
55ff9780
AD
524 default_blu= [VT]
525 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
526 Change the default blue palette of the console.
527 This is a 16-member array composed of values
528 ranging from 0-255.
529
530 default_grn= [VT]
531 Format: <green0>,<green1>,<green2>,...,<green15>
532 Change the default green palette of the console.
533 This is a 16-member array composed of values
534 ranging from 0-255.
535
536 default_red= [VT]
537 Format: <red0>,<red1>,<red2>,...,<red15>
538 Change the default red palette of the console.
539 This is a 16-member array composed of values
540 ranging from 0-255.
541
542 default_utf8= [VT]
543 Format=<0|1>
544 Set system-wide default UTF-8 mode for all tty's.
545 Default is 0 and by setting to 1, it enables UTF-8
546 mode for all newly opened or allocated terminals.
547
1da177e4
LT
548 dhash_entries= [KNL]
549 Set number of hash buckets for dentry cache.
a9913044 550
1da177e4
LT
551 digi= [HW,SERIAL]
552 IO parameters + enable/disable command.
553
554 digiepca= [HW,SERIAL]
555 See drivers/char/README.epca and
556 Documentation/digiepca.txt.
557
558 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
559 support available.
560 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
561
562 dmasound= [HW,OSS] Sound subsystem buffers
563
564 dscc4.setup= [NET]
565
566 dtc3181e= [HW,SCSI]
567
0ae53640 568 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
569 earlyprintk=vga
570 earlyprintk=serial[,ttySn[,baudrate]]
571
a9913044 572 Append ",keep" to not disable it when the real console
1da177e4
LT
573 takes over.
574
575 Only vga or serial at a time, not both.
576
577 Currently only ttyS0 and ttyS1 are supported.
578
579 Interaction with the standard serial driver is not
580 very good.
581
582 The VGA output is eventually overwritten by the real
583 console.
584
585 eata= [HW,SCSI]
586
53f11d4f
LB
587 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
588 Format: <int>
589 0: polling mode
590 non-0: interrupt mode (default)
591
1da177e4
LT
592 eda= [HW,PS2]
593
594 edb= [HW,PS2]
595
596 edd= [EDD]
597 Format: {"of[f]" | "sk[ipmbr]"}
598 See comment in arch/i386/boot/edd.S
599
a9913044 600 eicon= [HW,ISDN]
1da177e4
LT
601 Format: <id>,<membase>,<irq>
602
603 eisa_irq_edge= [PARISC,HW]
604 See header of drivers/parisc/eisa.c.
605
cd4f0ef7 606 elanfreq= [X86-32]
1da177e4
LT
607 See comment before function elanfreq_setup() in
608 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
609
610 elevator= [IOSCHED]
16ab3adf 611 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
612 See Documentation/block/as-iosched.txt and
613 Documentation/block/deadline-iosched.txt for details.
614
cd4f0ef7 615 elfcorehdr= [X86-32, X86_64]
a9913044 616 Specifies physical address of start of kernel core
aac04b32
VG
617 image elf header. Generally kexec loader will
618 pass this option to capture kernel.
619 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
620
621 enforcing [SELINUX] Set initial enforcing status.
622 Format: {"0" | "1"}
623 See security/selinux/Kconfig help text.
624 0 -- permissive (log only, no denials).
625 1 -- enforcing (deny and log).
626 Default value is 0.
627 Value can be changed at runtime via /selinux/enforce.
628
1da177e4
LT
629 es1371= [HW,OSS]
630 Format: <spdif>,[<nomix>,[<amplifier>]]
631 See also header of sound/oss/es1371.c.
a9913044 632
1da177e4
LT
633 ether= [HW,NET] Ethernet cards parameters
634 This option is obsoleted by the "netdev=" option, which
635 has equivalent usage. See its documentation for details.
636
637 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
638 Format: <io>[,<irq>]
639
de1ba09b
AM
640 failslab=
641 fail_page_alloc=
642 fail_make_request=[KNL]
643 General fault injection mechanism.
644 Format: <interval>,<probability>,<space>,<times>
645 See also /Documentation/fault-injection/.
646
1da177e4
LT
647 fd_mcs= [HW,SCSI]
648 See header of drivers/scsi/fd_mcs.c.
649
650 fdomain= [HW,SCSI]
651 See header of drivers/scsi/fdomain.c.
652
653 floppy= [HW]
654 See Documentation/floppy.txt.
655
1da177e4
LT
656 gamecon.map[2|3]=
657 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
658 support via parallel port (up to 5 devices per port)
659 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
660 See also Documentation/input/joystick-parport.txt
661
662 gamma= [HW,DRM]
663
664 gdth= [HW,SCSI]
665 See header of drivers/scsi/gdth.c.
666
667 gpt [EFI] Forces disk with valid GPT signature but
668 invalid Protective MBR to be treated as GPT.
669
1da177e4
LT
670 gvp11= [HW,SCSI]
671
672 hashdist= [KNL,NUMA] Large hashes allocated during boot
673 are distributed across NUMA nodes. Defaults on
674 for IA-64, off otherwise.
a9913044 675 Format: 0 | 1 (for off | on)
1da177e4
LT
676
677 hcl= [IA-64] SGI's Hardware Graph compatibility layer
678
679 hd= [EIDE] (E)IDE hard drive subsystem geometry
680 Format: <cyl>,<head>,<sect>
681
682 hd?= [HW] (E)IDE subsystem
683 hd?lun= See Documentation/ide.txt.
684
685 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
686 size of <nn>. This works even on boxes that have no
687 highmem otherwise. This also works to reduce highmem
688 size on bigger boxes.
689
54cdfdb4
TG
690 highres= [KNL] Enable/disable high resolution timer mode.
691 Valid parameters: "on", "off"
692 Default: "on"
693
1da177e4
LT
694 hisax= [HW,ISDN]
695 See Documentation/isdn/README.HiSax.
696
cd4f0ef7 697 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
1da177e4 698
1da177e4 699 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
700 i8042.dumbkbd [HW] Pretend that controller can only read data from
701 keyboard and cannot control its state
1da177e4
LT
702 (Don't attempt to blink the leds)
703 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 704 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
705 i8042.nomux [HW] Don't check presence of an active multiplexing
706 controller
707 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
708 controllers
709 i8042.panicblink=
710 [HW] Frequency with which keyboard LEDs should blink
711 when kernel panics (default is 0.5 sec)
712 i8042.reset [HW] Reset the controller during init and cleanup
713 i8042.unlock [HW] Unlock (ignore) the keylock
714
715 i810= [HW,DRM]
716
e70c9d5e
DT
717 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
718 indicates that the driver is running on unsupported
719 hardware.
1da177e4
LT
720 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
721 does not match list of supported models.
722 i8k.power_status
723 [HW] Report power status in /proc/i8k
724 (disabled by default)
725 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
726 capability is set.
727
728 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
729 See Documentation/mca.txt.
730
731 icn= [HW,ISDN]
732 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
733
734 ide= [HW] (E)IDE subsystem
735 Format: ide=nodma or ide=doubler or ide=reverse
736 See Documentation/ide.txt.
737
738 ide?= [HW] (E)IDE subsystem
739 Format: ide?=noprobe or chipset specific parameters.
740 See Documentation/ide.txt.
a9913044 741
1da177e4
LT
742 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
743 See Documentation/ide.txt.
744
f039b754
AK
745 idle= [X86]
746 Format: idle=poll or idle=mwait
747 Poll forces a polling idle loop that can slightly improves the performance
748 of waking up a idle CPU, but will use a lot of power and make the system
749 run hot. Not recommended.
750 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
751 to not use it because it doesn't save as much power as a normal idle
752 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
753 as idle=poll.
a9913044 754
79290822
IM
755 ignore_loglevel [KNL]
756 Ignore loglevel setting - this will print /all/
757 kernel messages to the console. Useful for debugging.
758
1da177e4
LT
759 ihash_entries= [KNL]
760 Set number of hash buckets for inode cache.
761
762 in2000= [HW,SCSI]
763 See header of drivers/scsi/in2000.c.
764
765 init= [KNL]
766 Format: <full_path>
767 Run specified binary instead of /sbin/init as init
768 process.
769
770 initcall_debug [KNL] Trace initcalls as they are executed. Useful
771 for working out where the kernel is dying during
772 startup.
773
774 initrd= [BOOT] Specify the location of the initial ramdisk
775
776 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
777 Format: <irq>
778
779 inttest= [IA64]
780
781 io7= [HW] IO7 for Marvel based alpha systems
782 See comment before marvel_specify_io7 in
783 arch/alpha/kernel/core_marvel.c.
784
785 ip= [IP_PNP]
786 See Documentation/nfsroot.txt.
787
788 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
789 See comment before ip2_setup() in
790 drivers/char/ip2/ip2base.c.
1da177e4
LT
791
792 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
793 See header of drivers/scsi/ips.c.
794
72c4a13a
SH
795 ports= [IP_VS_FTP] IPVS ftp helper module
796 Default is 21.
797 Up to 8 (IP_VS_APP_MAX_PORTS) ports
798 may be specified.
799 Format: <port>,<port>....
800
200803df
AC
801 irqfixup [HW]
802 When an interrupt is not handled search all handlers
803 for it. Intended to get systems with badly broken
804 firmware running.
805
806 irqpoll [HW]
807 When an interrupt is not handled search all handlers
808 for it. Also check all handlers each timer
809 interrupt. Intended to get systems with badly broken
810 firmware running.
811
1da177e4 812 isapnp= [ISAPNP]
a9913044 813 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
814
815 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
816 Format:
817 <cpu number>,...,<cpu number>
818 or
819 <cpu number>-<cpu number> (must be a positive range in ascending order)
820 or a mixture
821 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
822 This option can be used to specify one or more CPUs
823 to isolate from the general SMP balancing and scheduling
824 algorithms. The only way to move a process onto or off
825 an "isolated" CPU is via the CPU affinity syscalls.
826 <cpu number> begins at 0 and the maximum value is
827 "number of CPUs in system - 1".
828
829 This option is the preferred way to isolate CPUs. The
a9913044
RD
830 alternative -- manually setting the CPU mask of all
831 tasks in the system -- can cause problems and
832 suboptimal load balancer performance.
1da177e4 833
a9913044 834 iucv= [HW,NET]
1da177e4
LT
835
836 js= [HW,JOY] Analog joystick
837 See Documentation/input/joystick.txt.
838
cd4f0ef7 839 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
840 specifies the amount of memory usable by the kernel
841 for non-movable allocations. The requested amount is
842 spread evenly throughout all nodes in the system. The
843 remaining memory in each node is used for Movable
844 pages. In the event, a node is too small to have both
845 kernelcore and Movable pages, kernelcore pages will
846 take priority and other nodes will have a larger number
847 of kernelcore pages. The Movable zone is used for the
848 allocation of pages that may be reclaimed or moved
849 by the page migration subsystem. This means that
850 HugeTLB pages may not be allocated from this zone.
851 Note that allocations like PTEs-from-HighMem still
852 use the HighMem zone if it exists, and the Normal
853 zone if it does not.
854
cd4f0ef7 855 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
856 is similar to kernelcore except it specifies the
857 amount of memory used for migratable allocations.
858 If both kernelcore and movablecore is specified,
859 then kernelcore will be at *least* the specified
860 value but may be more. If movablecore on its own
861 is specified, the administrator must be careful
862 that the amount of memory usable for all allocations
863 is not too small.
864
1da177e4
LT
865 keepinitrd [HW,ARM]
866
cd4f0ef7 867 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
868 in oops dumps.
869
870 l2cr= [PPC]
871
cd4f0ef7 872 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 873 disabled it.
1da177e4 874
cd4f0ef7 875 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
876 C2 power state.
877
1da177e4
LT
878 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
879 Format: addr:<io>,irq:<irq>
880
78e70c23
DJ
881 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
882 when set.
883 Format: <int>
884
1da177e4
LT
885 load_ramdisk= [RAM] List of ramdisks to load from floppy
886 See Documentation/ramdisk.txt.
887
a6b25b67
RD
888 lockd.nlm_grace_period=P [NFS] Assign grace period.
889 Format: <integer>
1da177e4 890
a6b25b67
RD
891 lockd.nlm_tcpport=N [NFS] Assign TCP port.
892 Format: <integer>
893
894 lockd.nlm_timeout=T [NFS] Assign timeout value.
895 Format: <integer>
896
897 lockd.nlm_udpport=M [NFS] Assign UDP port.
898 Format: <integer>
1da177e4
LT
899
900 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
901 Format: <irq>
902
903 loglevel= All Kernel Messages with a loglevel smaller than the
904 console loglevel will be printed to the console. It can
905 also be changed with klogd or other programs. The
906 loglevels are defined as follows:
907
908 0 (KERN_EMERG) system is unusable
909 1 (KERN_ALERT) action must be taken immediately
910 2 (KERN_CRIT) critical conditions
911 3 (KERN_ERR) error conditions
912 4 (KERN_WARNING) warning conditions
913 5 (KERN_NOTICE) normal but significant condition
914 6 (KERN_INFO) informational
915 7 (KERN_DEBUG) debug-level messages
916
917 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
918 Format: { n | nk | nM }
919 n must be a power of two. The default size
920 is set in the kernel config file.
1da177e4 921
accaa24c
RD
922 logo.nologo [FB] Disables display of the built-in Linux logo.
923 This may be used to provide more screen space for
924 kernel log messages and is useful when debugging
925 kernel boot problems.
926
1da177e4
LT
927 lp=0 [LP] Specify parallel ports to use, e.g,
928 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
929 lp=reset first parallel port). 'lp=0' disables the
930 lp=auto printer driver. 'lp=reset' (which can be
931 specified in addition to the ports) causes
932 attached printers to be reset. Using
933 lp=port1,port2,... specifies the parallel ports
934 to associate lp devices with, starting with
935 lp0. A port specification may be 'none' to skip
936 that lp device, or a parport name such as
937 'parport0'. Specifying 'lp=auto' instead of a
938 port specification list means that device IDs
939 from each port should be examined, to see if
940 an IEEE 1284-compliant printer is attached; if
941 so, the driver will manage that printer.
942 See also header of drivers/char/lp.c.
943
944 lpj=n [KNL]
945 Sets loops_per_jiffy to given constant, thus avoiding
946 time-consuming boot-time autodetection (up to 250 ms per
947 CPU). 0 enables autodetection (default). To determine
948 the correct value for your kernel, boot with normal
949 autodetection and see what value is printed. Note that
950 on SMP systems the preset will be applied to all CPUs,
951 which is likely to cause problems if your CPUs need
952 significantly divergent settings. An incorrect value
953 will cause delays in the kernel to be wrong, leading to
954 unpredictable I/O errors and other breakage. Although
955 unlikely, in the extreme case this might damage your
956 hardware.
957
958 ltpc= [NET]
959 Format: <io>,<irq>,<dma>
960
a9913044
RD
961 mac5380= [HW,SCSI] Format:
962 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 963
a9913044
RD
964 mac53c9x= [HW,SCSI] Format:
965 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 966
a9913044
RD
967 machvec= [IA64] Force the use of a particular machine-vector
968 (machvec) in a generic kernel.
969 Example: machvec=hpzx1_swiotlb
1da177e4 970
a9913044 971 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
972 be mounted
973 Format: <1-256>
974
975 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
976 should make use of. maxcpus=n : n >= 0 limits the
977 kernel to using 'n' processors. n=0 is a special case,
978 it is equivalent to "nosmp", which also disables
979 the IO APIC.
1da177e4 980
2b2c3750
BP
981 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
982 equal to this physical address is ignored.
983
a9913044 984 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
985 Should be between 1 and 2^32-1.
986
987 max_report_luns=
a9913044 988 [SCSI] Maximum number of LUNs received.
1da177e4
LT
989 Should be between 1 and 16384.
990
cd4f0ef7 991 mca-pentium [BUGS=X86-32]
1da177e4
LT
992
993 mcatest= [IA-64]
994
cd4f0ef7 995 mce [X86-32] Machine Check Exception
1da177e4
LT
996
997 md= [HW] RAID subsystems devices and level
998 See Documentation/md.txt.
a9913044 999
1da177e4
LT
1000 mdacon= [MDA]
1001 Format: <first>,<last>
1002 Specifies range of consoles to be captured by the MDA.
a9913044 1003
1da177e4
LT
1004 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1005 Amount of memory to be used when the kernel is not able
1006 to see the whole system memory or for test.
cd4f0ef7 1007 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1008 address space collisions. Without memmap= PCI devices
1009 could be placed at addresses belonging to unused RAM.
1010
cd4f0ef7 1011 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1012 memory.
1013
cd4f0ef7 1014 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1015 E820 memory map, as specified by the user.
1016 Such memmap=exactmap lines can be constructed based on
1017 BIOS output or other requirements. See the memmap=nn@ss
1018 option description.
1019
1020 memmap=nn[KMG]@ss[KMG]
1021 [KNL] Force usage of a specific region of memory
1022 Region of memory to be used, from ss to ss+nn.
1023
1024 memmap=nn[KMG]#ss[KMG]
1025 [KNL,ACPI] Mark specific memory as ACPI data.
1026 Region of memory to be used, from ss to ss+nn.
1027
1028 memmap=nn[KMG]$ss[KMG]
1029 [KNL,ACPI] Mark specific memory as reserved.
1030 Region of memory to be used, from ss to ss+nn.
1031
1032 meye.*= [HW] Set MotionEye Camera parameters
1033 See Documentation/video4linux/meye.txt.
1034
8f36881b
AS
1035 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1036 Multi-Function General Purpose Timers on AMD Geode
1037 platforms.
1038
1da177e4
LT
1039 mga= [HW,DRM]
1040
1041 mousedev.tap_time=
1042 [MOUSE] Maximum time between finger touching and
1043 leaving touchpad surface for touch to be considered
1044 a tap and be reported as a left button click (for
1045 touchpads working in absolute mode only).
1046 Format: <msecs>
1047 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1048 reporting absolute coordinates, such as tablets
1049 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1050 reporting absolute coordinates, such as tablets
1051
1052 mpu401= [HW,OSS]
1053 Format: <io>,<irq>
1054
1055 MTD_Partition= [MTD]
1056 Format: <name>,<region-number>,<size>,<offset>
1057
a9913044
RD
1058 MTD_Region= [MTD] Format:
1059 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1060
1061 mtdparts= [MTD]
c8facbb6 1062 See drivers/mtd/cmdlinepart.c.
1da177e4
LT
1063
1064 mtouchusb.raw_coordinates=
a9913044
RD
1065 [HW] Make the MicroTouch USB driver use raw coordinates
1066 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1067
1068 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1069
1070 NCR_D700= [HW,SCSI]
1071 See header of drivers/scsi/NCR_D700.c.
1072
1073 ncr5380= [HW,SCSI]
1074
1075 ncr53c400= [HW,SCSI]
1076
1077 ncr53c400a= [HW,SCSI]
1078
1079 ncr53c406a= [HW,SCSI]
1080
1081 ncr53c8xx= [HW,SCSI]
1082
1083 netdev= [NET] Network devices parameters
1084 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1085 Note that mem_start is often overloaded to mean
1086 something different and driver-specific.
a9913044
RD
1087 This usage is only documented in each driver source
1088 file if at all.
1089
1da177e4
LT
1090 nfsaddrs= [NFS]
1091 See Documentation/nfsroot.txt.
1092
1093 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1094 See Documentation/nfsroot.txt.
1095
a72b4422
TM
1096 nfs.callback_tcpport=
1097 [NFS] set the TCP port on which the NFSv4 callback
1098 channel should listen.
1099
58df095b
TM
1100 nfs.idmap_cache_timeout=
1101 [NFS] set the maximum lifetime for idmapper cache
1102 entries.
1103
f43bf0be
TM
1104 nfs.enable_ino64=
1105 [NFS] enable 64-bit inode numbers.
1106 If zero, the NFS client will fake up a 32-bit inode
1107 number for the readdir() and stat() syscalls instead
1108 of returning the full 64-bit number.
1109 The default is to return 64-bit inode numbers.
1110
cd4f0ef7 1111 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1112
cd4f0ef7 1113 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1114 emulation library even if a 387 maths coprocessor
1115 is present.
1116
c1aee215
CL
1117 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1118 caches in the slab allocator. Saves per-node memory,
1119 but will impact performance.
3395ee05 1120
a9913044
RD
1121 noalign [KNL,ARM]
1122
1da177e4
LT
1123 noapic [SMP,APIC] Tells the kernel to not make use of any
1124 IOAPICs that may be present in the system.
1125
1126 noasync [HW,M68K] Disables async and sync negotiation for
1127 all devices.
1128
1129 nobats [PPC] Do not use BATs for mapping kernel lowmem
1130 on "Classic" PPC cores.
1131
1132 nocache [ARM]
a9913044 1133
163ecdff
SN
1134 nodelayacct [KNL] Disable per-task delay accounting
1135
1da177e4
LT
1136 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1137
1138 noexec [IA-64]
1139
cd4f0ef7 1140 noexec [X86-32,X86-64]
1da177e4
LT
1141 noexec=on: enable non-executable mappings (default)
1142 noexec=off: disable nn-executable mappings
1143
cd4f0ef7 1144 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1145 register save and restore. The kernel will only save
1146 legacy floating-point registers on task switch.
1da177e4
LT
1147
1148 nohlt [BUGS=ARM]
a9913044 1149
cd4f0ef7 1150 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1151 instruction doesn't work correctly and not to
1152 use it.
1153
1154 nohalt [IA-64] Tells the kernel not to use the power saving
1155 function PAL_HALT_LIGHT when idle. This increases
1156 power-consumption. On the positive side, it reduces
1157 interrupt wake-up latency, which may improve performance
1158 in certain environments such as networked servers or
1159 real-time systems.
1160
79bf2bb3
TG
1161 nohz= [KNL] Boottime enable/disable dynamic ticks
1162 Valid arguments: on, off
1163 Default: on
1164
cd4f0ef7 1165 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
8542b200 1166
cd4f0ef7 1167 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1168 disable unhandled interrupt sources.
1169
cd4f0ef7 1170 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1171 broken timer IRQ sources.
1172
1da177e4
LT
1173 noisapnp [ISAPNP] Disables ISA PnP code.
1174
1175 noinitrd [RAM] Tells the kernel not to load any configured
1176 initial RAM disk.
1177
1178 nointroute [IA-64]
1179
0aa366f3
TL
1180 nojitter [IA64] Disables jitter checking for ITC timers.
1181
cd4f0ef7 1182 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1183
cd4f0ef7 1184 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1185
1da177e4
LT
1186 noltlbs [PPC] Do not use large page/tlb entries for kernel
1187 lowmem mapping on PPC40x.
1188
312f1f01
H
1189 nomca [IA-64] Disable machine check abort handling
1190
cd4f0ef7 1191 nomce [X86-32] Machine Check Exception
abe37e5a 1192
83d7384f
AS
1193 nomfgpt [X86-32] Disable Multi-Function General Purpose
1194 Timer usage (for AMD Geode machines).
1195
cd4f0ef7 1196 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1197
cd4f0ef7 1198 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1199 with UP alternatives
1200
1da177e4
LT
1201 noresidual [PPC] Don't use residual data on PReP machines.
1202
a9913044
RD
1203 noresume [SWSUSP] Disables resume and restores original swap
1204 space.
1205
1da177e4
LT
1206 no-scroll [VGA] Disables scrollback.
1207 This is required for the Braillex ib80-piezo Braille
1208 reader made by F.H. Papenmeier (Germany).
1209
1210 nosbagart [IA-64]
1211
cd4f0ef7 1212 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1213
61ec7567
LB
1214 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1215 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1216
97842216
DJ
1217 nosoftlockup [KNL] Disable the soft-lockup detector.
1218
1da177e4
LT
1219 nosync [HW,M68K] Disables sync negotiation for all devices.
1220
cd4f0ef7 1221 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1222
1223 nousb [USB] Disable the USB subsystem
1224
1225 nowb [ARM]
a9913044 1226
f0c0b2b8
KH
1227 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1228 one of ['zone', 'node', 'default'] can be specified
1229 This can be set from sysctl after boot.
1230 See Documentation/sysctl/vm.txt for details.
1231
a61c2d78
DJ
1232 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1233
1da177e4
LT
1234 opl3= [HW,OSS]
1235 Format: <io>
1236
1da177e4
LT
1237 oprofile.timer= [HW]
1238 Use timer interrupt instead of performance counters
1239
1da177e4
LT
1240 osst= [HW,SCSI] SCSI Tape Driver
1241 Format: <buffer_size>,<write_threshold>
1242 See also Documentation/scsi/st.txt.
1243
1244 panic= [KNL] Kernel behaviour on panic
1245 Format: <timeout>
1246
1247 parkbd.port= [HW] Parallel port number the keyboard adapter is
1248 connected to, default is 0.
1249 Format: <parport#>
1250 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1251 0 for XT, 1 for AT (default is AT).
a9913044
RD
1252 Format: <mode>
1253
1254 parport= [HW,PPT] Specify parallel ports. 0 disables.
1255 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1256 Use 'auto' to force the driver to use any
1257 IRQ/DMA settings detected (the default is to
1258 ignore detected IRQ/DMA settings because of
1259 possible conflicts). You can specify the base
1260 address, IRQ, and DMA settings; IRQ and DMA
1261 should be numbers, or 'auto' (for using detected
1262 settings on that particular port), or 'nofifo'
1263 (to avoid using a FIFO even if it is detected).
1264 Parallel ports are assigned in the order they
1265 are specified on the command line, starting
1266 with parport0.
1267
1268 parport_init_mode= [HW,PPT]
1269 Configure VIA parallel port to operate in
1270 a specific mode. This is necessary on Pegasos
1271 computer where firmware has no options for setting
1272 up parallel port mode and sets it to spp.
1273 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1274 Format: [spp|ps2|epp|ecp|ecpepp]
1275
a9913044
RD
1276 pas2= [HW,OSS] Format:
1277 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1278
1da177e4
LT
1279 pas16= [HW,SCSI]
1280 See header of drivers/scsi/pas16.c.
1281
dd287796
AM
1282 pause_on_oops=
1283 Halt all CPUs after the first oops has been printed for
1284 the specified number of seconds. This is to be used if
1285 your oopses keep scrolling off the screen.
1286
1da177e4
LT
1287 pcbit= [HW,ISDN]
1288
1289 pcd. [PARIDE]
1290 See header of drivers/block/paride/pcd.c.
1291 See also Documentation/paride.txt.
1292
a9913044 1293 pci=option[,option...] [PCI] various PCI subsystem options:
cd4f0ef7
AC
1294 off [X86-32] don't probe for the PCI bus
1295 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1296 the hardware directly. Use this if your machine
1297 has a non-standard PCI host bridge.
cd4f0ef7 1298 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1299 hardware access methods are allowed. Use this
1300 if you experience crashes upon bootup and you
1301 suspect they are caused by the BIOS.
cd4f0ef7 1302 conf1 [X86-32] Force use of PCI Configuration
a9913044 1303 Mechanism 1.
cd4f0ef7 1304 conf2 [X86-32] Force use of PCI Configuration
a9913044 1305 Mechanism 2.
7f785763
RD
1306 noaer [PCIE] If the PCIEAER kernel config parameter is
1307 enabled, this kernel boot option can be used to
1308 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1309 nodomains [PCI] Disable support for multiple PCI
1310 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1311 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1312 Configuration
309e57df
MW
1313 nomsi [MSI] If the PCI_MSI kernel config parameter is
1314 enabled, this kernel boot option can be used to
1315 disable the use of MSI interrupts system-wide.
cd4f0ef7 1316 nosort [X86-32] Don't sort PCI devices according to
a9913044
RD
1317 order given by the PCI BIOS. This sorting is
1318 done to get a device order compatible with
1319 older kernels.
cd4f0ef7 1320 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1321 routing table. These calls are known to be buggy
1322 on several machines and they hang the machine
1323 when used, but on other computers it's the only
1324 way to get the interrupt routing table. Try
1325 this option if the kernel is unable to allocate
1326 IRQs or discover secondary PCI buses on your
1327 motherboard.
cd4f0ef7 1328 rom [X86-32] Assign address space to expansion ROMs.
a9913044
RD
1329 Use with caution as certain devices share
1330 address decoders between ROMs and other
1331 resources.
cd4f0ef7 1332 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
a9913044
RD
1333 assigned automatically to PCI devices. You can
1334 make the kernel exclude IRQs of your ISA cards
1335 this way.
cd4f0ef7 1336 pirqaddr=0xAAAAA [X86-32] Specify the physical address
a9913044
RD
1337 of the PIRQ table (normally generated
1338 by the BIOS) if it is outside the
1339 F0000h-100000h range.
cd4f0ef7 1340 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
a9913044
RD
1341 useful if the kernel is unable to find your
1342 secondary buses and you want to tell it
1343 explicitly which ones they are.
cd4f0ef7 1344 assign-busses [X86-32] Always assign all PCI bus
a9913044
RD
1345 numbers ourselves, overriding
1346 whatever the firmware may have done.
cd4f0ef7 1347 usepirqmask [X86-32] Honor the possible IRQ mask stored
a9913044
RD
1348 in the BIOS $PIR table. This is needed on
1349 some systems with broken BIOSes, notably
1350 some HP Pavilion N5400 and Omnibook XE3
1351 notebooks. This will have no effect if ACPI
1352 IRQ routing is enabled.
cd4f0ef7 1353 noacpi [X86-32] Do not use ACPI for IRQ routing
a9913044 1354 or for PCI scanning.
62f420f8
GH
1355 use_crs [X86-32] Use _CRS for PCI resource
1356 allocation.
a9913044
RD
1357 routeirq Do IRQ routing for all PCI devices.
1358 This is normally done in pci_enable_device(),
1359 so this option is a temporary workaround
1360 for broken drivers that don't call it.
1361 firmware [ARM] Do not re-enumerate the bus but instead
1362 just use the configuration from the
1363 bootloader. This is currently used on
1364 IXP2000 systems where the bus has to be
1365 configured a certain way for adjunct CPUs.
0637a70a
AK
1366 noearly [X86] Don't do any early type 1 scanning.
1367 This might help on some broken boards which
1368 machine check when some devices' config space
1369 is read. But various workarounds are disabled
1370 and some IOMMU drivers will not work.
6b4b78fe
MD
1371 bfsort Sort PCI devices into breadth-first order.
1372 This sorting is done to get a device
1373 order compatible with older (<= 2.4) kernels.
1374 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1375 cbiosize=nn[KMG] The fixed amount of bus space which is
1376 reserved for the CardBus bridge's IO window.
1377 The default value is 256 bytes.
1378 cbmemsize=nn[KMG] The fixed amount of bus space which is
1379 reserved for the CardBus bridge's memory
1380 window. The default value is 64 megabytes.
6b4b78fe 1381
1da177e4
LT
1382 pcmv= [HW,PCMCIA] BadgePAD 4
1383
1384 pd. [PARIDE]
1385 See Documentation/paride.txt.
1386
1387 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1388 boot time.
1389 Format: { 0 | 1 }
1390 See arch/parisc/kernel/pdc_chassis.c
1391
1392 pf. [PARIDE]
1393 See Documentation/paride.txt.
1394
1395 pg. [PARIDE]
1396 See Documentation/paride.txt.
1397
1398 pirq= [SMP,APIC] Manual mp-table setup
1399 See Documentation/i386/IO-APIC.txt.
1400
1401 plip= [PPT,NET] Parallel port network link
1402 Format: { parport<nr> | timid | 0 }
1403 See also Documentation/parport.txt.
1404
1405 pnpacpi= [ACPI]
1406 { off }
1407
1408 pnpbios= [ISAPNP]
1409 { on | off | curr | res | no-curr | no-res }
1410
1411 pnp_reserve_irq=
1412 [ISAPNP] Exclude IRQs for the autoconfiguration
1413
1414 pnp_reserve_dma=
1415 [ISAPNP] Exclude DMAs for the autoconfiguration
1416
1417 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1418 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1419
1420 pnp_reserve_mem=
a9913044
RD
1421 [ISAPNP] Exclude memory regions for the
1422 autoconfiguration.
1da177e4
LT
1423 Ranges are in pairs (memory base and size).
1424
45807a1d
IM
1425 print-fatal-signals=
1426 [KNL] debug: print fatal signals
1427 print-fatal-signals=1: print segfault info to
1428 the kernel console.
1429 default: off.
1430
e84845c4
RD
1431 printk.time= Show timing data prefixed to each printk message line
1432 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1433
1da177e4 1434 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1435 Format: [schedule,]<number>
1436 Param: "schedule" - profile schedule points.
1437 Param: <number> - step/bucket size as a power of 2 for
1438 statistical time based profiling.
ece8a684 1439 Param: "sleep" - profile D-state sleeping (millisecs)
1da177e4 1440
a9913044 1441 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1442 Limit processor to maximum C-state
1443 max_cstate=9 overrides any DMI blacklist limit.
1444
41c0d868
LB
1445 processor.nocst [HW,ACPI]
1446 Ignore the _CST method to determine C-states,
1447 instead using the legacy FADT method
1448
1da177e4
LT
1449 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1450 before loading.
1451 See Documentation/ramdisk.txt.
1452
a9913044
RD
1453 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1454 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1455 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1456 per second.
a9913044
RD
1457 psmouse.resetafter= [HW,MOUSE]
1458 Try to reset the device after so many bad packets
1da177e4
LT
1459 (0 = never).
1460 psmouse.resolution=
1461 [HW,MOUSE] Set desired mouse resolution, in dpi.
1462 psmouse.smartscroll=
a9913044 1463 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1464 0 = disabled, 1 = enabled (default).
1465
1466 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1467 Format:
1468 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1469
1470 pt. [PARIDE]
1471 See Documentation/paride.txt.
1472
dc8c8587
KS
1473 pty.legacy_count=
1474 [KNL] Number of legacy pty's. Overwrites compiled-in
1475 default number.
1476
7d2c502f 1477 quiet [KNL] Disable most log messages
a9913044 1478
1da177e4
LT
1479 r128= [HW,DRM]
1480
1481 raid= [HW,RAID]
1482 See Documentation/md.txt.
1483
a9913044 1484 ramdisk_blocksize= [RAM]
1da177e4 1485 See Documentation/ramdisk.txt.
a9913044 1486
1da177e4 1487 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1da177e4
LT
1488 See Documentation/ramdisk.txt.
1489
21a1ea9e
DS
1490 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1491 RCU callbacks to process in one batch.
1492
1493 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1494 RCU callbacks over which batch limiting is disabled.
1495
1496 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1497 RCU callbacks below which batch limiting is re-enabled.
1498
ffdfc409
OJ
1499 rdinit= [KNL]
1500 Format: <full_path>
1501 Run specified binary instead of /init from the ramdisk,
1502 used for early userspace startup. See initrd.
1503
cd4f0ef7 1504 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1505 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1506 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4
LT
1507
1508 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1509
cd4f0ef7 1510 reservetop= [X86-32]
461a9aff
ZA
1511 Format: nn[KMG]
1512 Reserves a hole at the top of the kernel virtual
1513 address space.
1514
7e96287d
VG
1515 reset_devices [KNL] Force drivers to reset the underlying device
1516 during initialization.
1517
a9913044
RD
1518 resume= [SWSUSP]
1519 Specify the partition device for software suspend
1da177e4 1520
ecbd0da1
RW
1521 resume_offset= [SWSUSP]
1522 Specify the offset from the beginning of the partition
1523 given by "resume=" at which the swap header is located,
1524 in <PAGE_SIZE> units (needed only for swap files).
1525 See Documentation/power/swsusp-and-swap-files.txt
1526
0a7b35cb
MN
1527 retain_initrd [RAM] Keep initrd memory after extraction
1528
1da177e4
LT
1529 rhash_entries= [KNL,NET]
1530 Set number of hash buckets for route cache
1531
1532 riscom8= [HW,SERIAL]
1533 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1534
1535 ro [KNL] Mount root device read-only on boot
1536
1537 root= [KNL] Root filesystem
1538
1539 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1540 mount the root filesystem
1541
1542 rootflags= [KNL] Set root filesystem mount option string
1543
1544 rootfstype= [KNL] Set root filesystem type
1545
cc1ed754
PO
1546 rootwait [KNL] Wait (indefinitely) for root device to show up.
1547 Useful for devices that are detected asynchronously
1548 (e.g. USB and MMC devices).
1549
20510f2f
JM
1550 root_plug.vendor_id=
1551 [ROOTPLUG] Override the default vendor ID
1552
1553 root_plug.product_id=
1554 [ROOTPLUG] Override the default product ID
1555
1556 root_plug.debug=
1557 [ROOTPLUG] Enable debugging output
1558
1da177e4
LT
1559 rw [KNL] Mount root device read-write on boot
1560
1561 S [KNL] Run init in single mode
1562
1563 sa1100ir [NET]
1564 See drivers/net/irda/sa1100_ir.c.
1565
1566 sb= [HW,OSS]
1567 Format: <io>,<irq>,<dma>,<dma2>
1568
1569 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1570
1da177e4
LT
1571 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1572 Format: <io>[,<timeout>[,<isapnp>]]
1573
1574 scsi_debug_*= [SCSI]
1575 See drivers/scsi/scsi_debug.c.
1576
1577 scsi_default_dev_flags=
1578 [SCSI] SCSI default device flags
1579 Format: <integer>
1580
1581 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1582 Format: <vendor>:<model>:<flags>
1583 (flags are integer value)
1584
1585 scsi_logging= [SCSI]
1586
3e082a91
MW
1587 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1588 discovered. async scans them in kernel threads,
1589 allowing boot to proceed. none ignores them, expecting
1590 user space to do the scan.
1591
1da177e4
LT
1592 selinux [SELINUX] Disable or enable SELinux at boot time.
1593 Format: { "0" | "1" }
1594 See security/selinux/Kconfig help text.
1595 0 -- disable.
1596 1 -- enable.
1597 Default value is set via kernel config option.
1598 If enabled at boot time, /selinux/disable can be used
1599 later to disable prior to initial policy load.
1600
4e5ab4cb
JM
1601 selinux_compat_net =
1602 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1603 Format: { "0" | "1" }
1604 0 -- use new secmark-based packet controls
1605 1 -- use legacy packet controls
1606 Default value is 0 (preferred).
1607 Value can be changed at runtime via
1608 /selinux/compat_net.
4e5ab4cb 1609
cd4f0ef7 1610 serialnumber [BUGS=X86-32]
1da177e4 1611
a9913044
RD
1612 sg_def_reserved_size= [SCSI]
1613
1da177e4
LT
1614 shapers= [NET]
1615 Maximal number of shapers.
a9913044 1616
1da177e4
LT
1617 sim710= [SCSI,HW]
1618 See header of drivers/scsi/sim710.c.
1619
1620 simeth= [IA-64]
1621 simscsi=
a9913044 1622
1da177e4
LT
1623 slram= [HW,MTD]
1624
f0630fff
CL
1625 slub_debug[=options[,slabs]] [MM, SLUB]
1626 Enabling slub_debug allows one to determine the
1627 culprit if slab objects become corrupted. Enabling
1628 slub_debug can create guard zones around objects and
1629 may poison objects when not in use. Also tracks the
1630 last alloc / free. For more information see
1631 Documentation/vm/slub.txt.
c1aee215
CL
1632
1633 slub_max_order= [MM, SLUB]
f0630fff
CL
1634 Determines the maximum allowed order for slabs.
1635 A high setting may cause OOMs due to memory
1636 fragmentation. For more information see
1637 Documentation/vm/slub.txt.
c1aee215
CL
1638
1639 slub_min_objects= [MM, SLUB]
f0630fff
CL
1640 The minimum number of objects per slab. SLUB will
1641 increase the slab order up to slub_max_order to
1642 generate a sufficiently large slab able to contain
1643 the number of objects indicated. The higher the number
1644 of objects the smaller the overhead of tracking slabs
1645 and the less frequently locks need to be acquired.
c1aee215
CL
1646 For more information see Documentation/vm/slub.txt.
1647
1648 slub_min_order= [MM, SLUB]
1649 Determines the mininum page order for slabs. Must be
f0630fff 1650 lower than slub_max_order.
c1aee215
CL
1651 For more information see Documentation/vm/slub.txt.
1652
1653 slub_nomerge [MM, SLUB]
f0630fff 1654 Disable merging of slabs with similar size. May be
c1aee215 1655 necessary if there is some reason to distinguish
f0630fff
CL
1656 allocs to different slabs. Debug options disable
1657 merging on their own.
c1aee215
CL
1658 For more information see Documentation/vm/slub.txt.
1659
1da177e4
LT
1660 smart2= [HW]
1661 Format: <io1>[,<io2>[,...,<io8>]]
1662
cd4f0ef7 1663 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
1664 attempt to substitute SMP alternatives once at boot.
1665
d0d4f69b
BH
1666 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1667 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1668 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1669 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1670 smsc-ircc2.ircc_irq= [HW] IRQ line
1671 smsc-ircc2.ircc_dma= [HW] DMA channel
1672 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1673 0: Toshiba Satellite 1800 (GP data pin select)
1674 1: Fast pin select (default)
1675 2: ATC IRMode
1676
1da177e4
LT
1677 snd-ad1816a= [HW,ALSA]
1678
1679 snd-ad1848= [HW,ALSA]
1680
1681 snd-ali5451= [HW,ALSA]
1682
1683 snd-als100= [HW,ALSA]
1684
1685 snd-als4000= [HW,ALSA]
1686
1687 snd-azt2320= [HW,ALSA]
1688
1689 snd-cmi8330= [HW,ALSA]
1690
1691 snd-cmipci= [HW,ALSA]
1692
1693 snd-cs4231= [HW,ALSA]
1694
1695 snd-cs4232= [HW,ALSA]
1696
1697 snd-cs4236= [HW,ALSA]
1698
1699 snd-cs4281= [HW,ALSA]
1700
1701 snd-cs46xx= [HW,ALSA]
1702
1703 snd-dt019x= [HW,ALSA]
1704
1705 snd-dummy= [HW,ALSA]
1706
1707 snd-emu10k1= [HW,ALSA]
1708
1709 snd-ens1370= [HW,ALSA]
1710
1711 snd-ens1371= [HW,ALSA]
1712
1713 snd-es968= [HW,ALSA]
1714
1715 snd-es1688= [HW,ALSA]
1716
1717 snd-es18xx= [HW,ALSA]
1718
1719 snd-es1938= [HW,ALSA]
1720
1721 snd-es1968= [HW,ALSA]
1722
1723 snd-fm801= [HW,ALSA]
1724
1725 snd-gusclassic= [HW,ALSA]
1726
1727 snd-gusextreme= [HW,ALSA]
1728
1729 snd-gusmax= [HW,ALSA]
1730
1731 snd-hdsp= [HW,ALSA]
1732
1733 snd-ice1712= [HW,ALSA]
1734
1735 snd-intel8x0= [HW,ALSA]
1736
1737 snd-interwave= [HW,ALSA]
1738
1739 snd-interwave-stb=
1740 [HW,ALSA]
1741
1742 snd-korg1212= [HW,ALSA]
1743
1744 snd-maestro3= [HW,ALSA]
1745
1746 snd-mpu401= [HW,ALSA]
1747
1748 snd-mtpav= [HW,ALSA]
1749
1750 snd-nm256= [HW,ALSA]
1751
1752 snd-opl3sa2= [HW,ALSA]
1753
1754 snd-opti92x-ad1848=
1755 [HW,ALSA]
1756
1757 snd-opti92x-cs4231=
1758 [HW,ALSA]
1759
1760 snd-opti93x= [HW,ALSA]
1761
1762 snd-pmac= [HW,ALSA]
1763
1764 snd-rme32= [HW,ALSA]
1765
1766 snd-rme96= [HW,ALSA]
1767
1768 snd-rme9652= [HW,ALSA]
1769
1770 snd-sb8= [HW,ALSA]
1771
1772 snd-sb16= [HW,ALSA]
1773
1774 snd-sbawe= [HW,ALSA]
1775
1776 snd-serial= [HW,ALSA]
1777
1778 snd-sgalaxy= [HW,ALSA]
1779
1780 snd-sonicvibes= [HW,ALSA]
1781
1782 snd-sun-amd7930=
1783 [HW,ALSA]
1784
1785 snd-sun-cs4231= [HW,ALSA]
1786
1787 snd-trident= [HW,ALSA]
1788
1789 snd-usb-audio= [HW,ALSA,USB]
1790
1791 snd-via82xx= [HW,ALSA]
1792
1793 snd-virmidi= [HW,ALSA]
1794
1795 snd-wavefront= [HW,ALSA]
1796
1797 snd-ymfpci= [HW,ALSA]
a9913044 1798
1da177e4
LT
1799 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1800 See Documentation/sonypi.txt
1801
1802 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1803 See Documentation/specialix.txt.
1804
1805 spia_io_base= [HW,MTD]
1806 spia_fio_base=
1807 spia_pedr=
1808 spia_peddr=
1809
1810 sscape= [HW,OSS]
1811 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1812
1da177e4
LT
1813 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1814 See Documentation/scsi/st.txt.
1815
1816 st0x= [HW,SCSI]
1817 See header of drivers/scsi/seagate.c.
1818
1819 sti= [PARISC,HW]
1820 Format: <num>
1821 Set the STI (builtin display/keyboard on the HP-PARISC
1822 machines) console (graphic card) which should be used
1823 as the initial boot-console.
1824 See also comment in drivers/video/console/sticore.c.
1825
1826 sti_font= [HW]
1827 See comment in drivers/video/console/sticore.c.
1828
1829 stifb= [HW]
1830 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1831
42a7fc4a
GB
1832 sunrpc.pool_mode=
1833 [NFS]
1834 Control how the NFS server code allocates CPUs to
1835 service thread pools. Depending on how many NICs
1836 you have and where their interrupts are bound, this
1837 option will affect which CPUs will do NFS serving.
1838 Note: this parameter cannot be changed while the
1839 NFS server is running.
1840
1841 auto the server chooses an appropriate mode
1842 automatically using heuristics
1843 global a single global pool contains all CPUs
1844 percpu one pool for each CPU
1845 pernode one pool for each NUMA node (equivalent
1846 to global on non-NUMA machines)
1847
1da177e4 1848 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1849
1da177e4
LT
1850 switches= [HW,M68k]
1851
1852 sym53c416= [HW,SCSI]
1853 See header of drivers/scsi/sym53c416.c.
1854
5d6f647f
IM
1855 sysrq_always_enabled
1856 [KNL]
1857 Ignore sysrq setting - this boot parameter will
1858 neutralize any effect of /proc/sys/kernel/sysrq.
1859 Useful for debugging.
1860
1da177e4
LT
1861 t128= [HW,SCSI]
1862 See header of drivers/scsi/t128.c.
1863
1864 tdfx= [HW,DRM]
1865
1866 thash_entries= [KNL,NET]
1867 Set number of hash buckets for TCP connection
1868
f8707ec9
LB
1869 thermal.act= [HW,ACPI]
1870 -1: disable all active trip points in all thermal zones
1871 <degrees C>: override all lowest active trip points
1872
c52a7419
LB
1873 thermal.crt= [HW,ACPI]
1874 -1: disable all critical trip points in all thermal zones
1875 <degrees C>: lower all critical trip points
1876
f5487145
LB
1877 thermal.nocrt= [HW,ACPI]
1878 Set to disable actions on ACPI thermal zone
1879 critical and hot trip points.
1880
72b33ef8
LB
1881 thermal.off= [HW,ACPI]
1882 1: disable ACPI thermal control
1883
a70cdc52
LB
1884 thermal.psv= [HW,ACPI]
1885 -1: disable all passive trip points
1886 <degrees C>: override all passive trip points to this value
1887
730ff34d
LB
1888 thermal.tzp= [HW,ACPI]
1889 Specify global default ACPI thermal zone polling rate
1890 <deci-seconds>: poll all this frequency
1891 0: no polling (default)
1892
1da177e4 1893 time Show timing data prefixed to each printk message line
e84845c4 1894 [deprecated, see 'printk.time']
1da177e4
LT
1895
1896 tipar.timeout= [HW,PPT]
1897 Set communications timeout in tenths of a second
1898 (default 15).
1899
1900 tipar.delay= [HW,PPT]
1901 Set inter-bit delay in microseconds (default 10).
1902
1903 tmc8xx= [HW,SCSI]
1904 See header of drivers/scsi/seagate.c.
1905
1906 tmscsim= [HW,SCSI]
1907 See comment before function dc390_setup() in
1908 drivers/scsi/tmscsim.c.
1909
1910 tp720= [HW,PS2]
1911
1912 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1913 Format:
1914 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1915
a9913044
RD
1916 turbografx.map[2|3]= [HW,JOY]
1917 TurboGraFX parallel port interface
1918 Format:
1919 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1920 See also Documentation/input/joystick-parport.txt
1921
1922 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1923 See header of drivers/scsi/u14-34f.c.
1924
1925 uart401= [HW,OSS]
1926 Format: <io>,<irq>
1927
1928 uart6850= [HW,OSS]
1929 Format: <io>,<irq>
1930
5f8364b7
AS
1931 uhci-hcd.ignore_oc=
1932 [USB] Ignore overcurrent events (default N).
1933 Some badly-designed motherboards generate lots of
1934 bogus events, for ports that aren't wired to
1935 anything. Set this parameter to avoid log spamming.
1936 Note that genuine overcurrent events won't be
1937 reported either.
1938
b5e795f8
AS
1939 usbcore.autosuspend=
1940 [USB] The autosuspend time delay (in seconds) used
1941 for newly-detected USB devices (default 2). This
1942 is the time required before an idle device will be
1943 autosuspended. Devices for which the delay is set
eaafbc3a 1944 to a negative value won't be autosuspended at all.
b5e795f8 1945
1da177e4
LT
1946 usbhid.mousepoll=
1947 [USBHID] The interval which mice are to be polled at.
a9913044 1948
cd4f0ef7 1949 vdso= [X86-32,SH,x86-64]
1dbf527c 1950 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
1951 vdso=1: enable VDSO (default)
1952 vdso=0: disable VDSO mapping
1953
d080d397
YI
1954 vector= [IA-64,SMP]
1955 vector=percpu: enable percpu vector domain
1956
1da177e4
LT
1957 video= [FB] Frame buffer configuration
1958 See Documentation/fb/modedb.txt.
1959
cd4f0ef7 1960 vga= [BOOT,X86-32] Select a particular video mode
a9913044
RD
1961 See Documentation/i386/boot.txt and
1962 Documentation/svga.txt.
1da177e4
LT
1963 Use vga=ask for menu.
1964 This is actually a boot loader parameter; the value is
1965 passed to the kernel using a special protocol.
1966
a9913044 1967 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1968 size of <nn>. This can be used to increase the
1969 minimum size (128MB on x86). It can also be used to
1970 decrease the size and leave more room for directly
1971 mapped kernel RAM.
1972
585c3047
PO
1973 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1974 Format: <command>
1da177e4 1975
585c3047
PO
1976 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1977 Format: <command>
1978
1979 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1980 Format: <command>
a9913044 1981
1da177e4
LT
1982 waveartist= [HW,OSS]
1983 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1984
1da177e4
LT
1985 wd33c93= [HW,SCSI]
1986 See header of drivers/scsi/wd33c93.c.
1987
1988 wd7000= [HW,SCSI]
1989 See header of drivers/scsi/wd7000.c.
1990
1991 wdt= [WDT] Watchdog
8dfe9c21 1992 See Documentation/watchdog/wdt.txt.
1da177e4
LT
1993
1994 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1995 xd_geo= See header of drivers/block/xd.c.
1996
1997 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1998 Format:
1999 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2000
a62eaf15
AK
2001 norandmaps Don't use address space randomization
2002 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2003
e53dd083 2004 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
6d0185ea
JB
2005 This is useful to get more information why
2006 you got a "dwarf2 unwinder stuck"
1da177e4 2007
a9913044 2008______________________________________________________________________
1da177e4
LT
2009
2010TODO:
2011
2012 Add documentation for ALSA options.
2013 Add more DRM drivers.