blob: fa885174fd7588031142b80cbb1f4d41b5bf0d62 [file] [log] [blame]
Stefan Richter0ee9d712006-04-01 01:42:29 +02001 Kernel Parameters
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 ~~~~~~~~~~~~~~~~~
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
Stefan Richtera901ebb2006-04-01 01:43:18 +020020This 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
Stefan Richter6585fa82006-04-01 01:44:30 +020027The 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:
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070038 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070047 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070051 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 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.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070060 MSI Message Signaled Interrupts (PCI).
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070064 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +020067 PV_OPS A paravirtualized kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 PARIDE The ParIDE subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCMCIA The PCMCIA subsystem is enabled.
72 PNP Plug & Play support is enabled.
73 PPC PowerPC architecture is enabled.
74 PPT Parallel port support is enabled.
75 PS2 Appropriate PS/2 support is enabled.
76 RAM RAM disk support is enabled.
77 S390 S390 architecture is enabled.
78 SCSI Appropriate SCSI support is enabled.
79 A lot of drivers has their options described inside of
80 Documentation/scsi/.
81 SELINUX SELinux support is enabled.
82 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090083 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 SMP The kernel is an SMP kernel.
85 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070086 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 TS Appropriate touchscreen support is enabled.
88 USB USB support is enabled.
89 USBHID USB Human Interface Device support is enabled.
90 V4L Video For Linux support is enabled.
91 VGA The VGA console has been enabled.
92 VT Virtual terminal support is enabled.
93 WDT Watchdog support is enabled.
94 XT IBM PC/XT MFM hard disk support is enabled.
95 X86-64 X86-64 architecture is enabled.
96 More X86-64 boot options can be found in
97 Documentation/x86_64/boot-options.txt .
98
99In addition, the following text indicates that the option:
100
101 BUGS= Relates to possible processor bugs on the said processor.
102 KNL Is a kernel start-up parameter.
103 BOOT Is a boot loader parameter.
104
105Parameters denoted with BOOT are actually interpreted by the boot
106loader, and have no meaning to the kernel directly.
107Do not modify the syntax of boot loader parameters without extreme
108need or coordination with <Documentation/i386/boot.txt>.
109
Karsten Weiss55588702007-02-13 13:26:21 +0100110There are also arch-specific kernel-parameters not documented here.
111See for example <Documentation/x86_64/boot-options.txt>.
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
114a trailing = on the name of any parameter states that that parameter will
115be entered as an environment variable, whereas its absence indicates that
116it will appear as a kernel argument readable via /proc/cmdline by programs
117running once the system is up.
118
jens m. noedler9c4751f2006-09-29 02:00:27 -0700119The number of kernel parameters is not limited, but the length of the
120complete command line (parameters including spaces etc.) is limited to
121a fixed number of characters. This limit depends on the architecture
122and is between 256 and 4096 characters. It is defined in the file
123./include/asm/setup.h as COMMAND_LINE_SIZE.
124
125
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 53c7xx= [HW,SCSI] Amiga SCSI controllers
127 See header of drivers/scsi/53c7xx.c.
128 See also Documentation/scsi/ncr53c7xx.txt.
129
Bernhard Walle03d926f2007-03-06 02:29:44 -0800130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700132 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 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
Randy Dunlapa9913042005-10-23 12:57:11 -0700137 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 strictly ACPI specification compliant.
139
140 See also Documentation/pm.txt, pci=noacpi
141
Len Browna1fdcc02007-03-11 03:26:14 -0400142 acpi_apic_instance= [ACPI, IOAPIC]
143 Format: <int>
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400146 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400147
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700153 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Randy Dunlapa9913042005-10-23 12:57:11 -0700155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
157 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
Randy Dunlapa9913042005-10-23 12:57:11 -0700159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
161 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162
Randy Dunlapa9913042005-10-23 12:57:11 -0700163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 Format: <irq>,<irq>...
166
Randy Dunlapa9913042005-10-23 12:57:11 -0700167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 Format: <irq>,<irq>...
169
Len Browna1f9e652006-01-25 23:47:36 -0500170 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
171 Format: To spoof as Windows 98: ="Microsoft Windows"
172
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 acpi_osi= [HW,ACPI] empty param disables _OSI
174
175 acpi_serialize [HW,ACPI] force serialization of AML methods
176
177 acpi_skip_timer_override [HW,ACPI]
178 Recognize and ignore IRQ0/pin2 Interrupt Override.
179 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100180 acpi_use_timer_override [HW,ACPI}
181 Use timer override. For some broken Nvidia NF5 boards
182 that require a timer override, but don't have
183 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
Zhang Ruif9891062007-04-24 13:53:22 +0800185 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700187 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 1: enable, 0: disable. It is useful for boot time
189 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800190 via /sys/module/acpi/parameters/debug_layer.
191 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
192 Available bits (add the numbers together) to enable debug output
193 for specific parts of the ACPI subsystem:
194 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
195 0x10 namespace 0x20 parser 0x40 dispatcher
196 0x80 executer 0x100 resources 0x200 acpica debugger
197 0x400 os services 0x800 acpica disassembler.
198 The number can be in decimal or prefixed with 0x in hex.
199 Warning: Many of these options can produce a lot of
200 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
Zhang Ruif9891062007-04-24 13:53:22 +0800202 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700204 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 1: enable, 0: disable. It is useful for boot time
206 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800207 via /sys/module/acpi/parameters/debug_level.
208 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
209 Available bits (add the numbers together) to enable different
210 debug output levels of the ACPI subsystem:
211 0x01 error 0x02 warn 0x04 init 0x08 debug object
212 0x10 info 0x20 init names 0x40 parse 0x80 load
213 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
214 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
215 0x10000 resources 0x20000 user requests 0x40000 package.
216 The number can be in decimal or prefixed with 0x in hex.
217 Warning: Many of these options can produce a lot of
218 output and make your system unusable. Be very careful.
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
222
Luming Yu30e332f2005-08-12 00:31:00 -0400223 acpi_generic_hotkey [HW,ACPI]
224 Allow consolidated generic hotkey driver to
Randy Dunlapa9913042005-10-23 12:57:11 -0700225 override platform specific driver.
Luming Yu30e332f2005-08-12 00:31:00 -0400226 See also Documentation/acpi-hotkey.txt.
227
john stultz5d0cf412006-06-26 00:25:12 -0700228 acpi_pm_good [IA-32,X86-64]
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
Chuck Ebbert66759a02005-09-12 18:49:25 +0200233 enable_timer_pin_1 [i386,x86-64]
234 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700235 Can be useful to work around chipset bugs
236 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200237 The kernel tries to set a reasonable default.
238
239 disable_timer_pin_1 [i386,x86-64]
240 Disable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs.
242
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 ad1816= [HW,OSS]
244 Format: <io>,<irq>,<dma>,<dma2>
245 See also Documentation/sound/oss/AD1816.
246
247 ad1848= [HW,OSS]
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
249
250 adlib= [HW,OSS]
251 Format: <io>
Randy Dunlapa9913042005-10-23 12:57:11 -0700252
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 advansys= [HW,SCSI]
254 See header of drivers/scsi/advansys.c.
255
256 advwdt= [HW,WDT] Advantech WDT
257 Format: <iostart>,<iostop>
258
259 aedsp16= [HW,OSS] Audio Excel DSP 16
260 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
261 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700262
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 aha152x= [HW,SCSI]
264 See Documentation/scsi/aha152x.txt.
265
266 aha1542= [HW,SCSI]
267 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
268
269 aic7xxx= [HW,SCSI]
270 See Documentation/scsi/aic7xxx.txt.
271
272 aic79xx= [HW,SCSI]
273 See Documentation/scsi/aic79xx.txt.
274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 amijoy.map= [HW,JOY] Amiga joystick support
276 Map of devices attached to JOY0DAT and JOY1DAT
277 Format: <a>,<b>
278 See also Documentation/kernel/input/joystick.txt
279
280 analog.map= [HW,JOY] Analog joystick and gamepad support
281 Specifies type or capabilities of an analog joystick
282 connected to one of 16 gameports
283 Format: <type1>,<type2>,..<type16>
284
Randy Dunlapa9913042005-10-23 12:57:11 -0700285 apc= [HW,SPARC]
286 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 Format: noidle
288 Disable APC CPU standby support. SPARCstation-Fox does
289 not play well with APC CPU idle - disable it if you have
290 APC and your system crashes randomly.
291
Randy Dunlapa9913042005-10-23 12:57:11 -0700292 apic= [APIC,i386] Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700296
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
299
300 applicom= [HW]
301 Format: <mem>,<irq>
Randy Dunlapa9913042005-10-23 12:57:11 -0700302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 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
Randy Dunlapa9913042005-10-23 12:57:11 -0700317 atkbd.set= [HW] Select keyboard code set
318 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
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))
Randy Dunlapa9913042005-10-23 12:57:11 -0700325
326 atkbd.softrepeat= [HW]
327 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328
329 autotest [IA64]
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 aztcd= [HW,CD] Aztech CD268 CDROM driver
332 Format: <io>,0x79 (?)
333
334 baycom_epp= [HW,AX25]
335 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
338 Format: <io>,<mode>
339 See header of drivers/net/hamradio/baycom_par.c.
340
Randy Dunlapa9913042005-10-23 12:57:11 -0700341 baycom_ser_fdx= [HW,AX25]
342 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 Format: <io>,<irq>,<mode>[,<baud>]
344 See header of drivers/net/hamradio/baycom_ser_fdx.c.
345
Randy Dunlapa9913042005-10-23 12:57:11 -0700346 baycom_ser_hdx= [HW,AX25]
347 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 Format: <io>,<irq>,<mode>
349 See header of drivers/net/hamradio/baycom_ser_hdx.c.
350
351 blkmtd_device= [HW,MTD]
352 blkmtd_erasesz=
353 blkmtd_ro=
354 blkmtd_bs=
355 blkmtd_count=
356
357 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700358 bttv.radio= Most important insmod options are available as
359 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
361 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
362
363 BusLogic= [HW,SCSI]
364 See drivers/scsi/BusLogic.c, comment before function
365 BusLogic_ParseDriverOptions().
366
367 c101= [NET] Moxa C101 synchronous serial card
368
369 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
370 Sometimes CPU hardware bugs make them report the cache
371 size incorrectly. The kernel will attempt work arounds
372 to fix known problems, but for some CPUs it is not
373 possible to determine what the correct size should be.
374 This option provides an override for these situations.
375
376 cdu31a= [HW,CD]
377 Format: <io>,<irq>[,PAS]
378 See header of drivers/cdrom/cdu31a.c.
379
380 chandev= [HW,NET] Generic channel device initialisation
381
382 checkreqprot [SELINUX] Set initial checkreqprot flag value.
383 Format: { "0" | "1" }
384 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700385 0 -- check protection applied by kernel (includes
386 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 1 -- check protection requested by application.
388 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700389 Value can be changed at runtime via
390 /selinux/checkreqprot.
391
john stultz734efb42006-06-26 00:25:05 -0700392 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
393 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200394 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700395 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200396 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 Format: { pit | tsc | cyclone | pmtmr }
398
Chuck Ebbert86c41832007-02-13 13:26:25 +0100399 code_bytes [IA32] How many bytes of object code to print in an
400 oops report.
401 Range: 0 - 8192
402 Default: 64
403
Andi Kleenf9262c12006-03-08 17:57:25 -0800404 disable_8254_timer
405 enable_8254_timer
406 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
407 over the 8254 in addition to over the IO-APIC. The
408 kernel tries to set a sensible default.
409
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 hpet= [IA-32,HPET] option to disable HPET and use PIT.
411 Format: disable
412
413 cm206= [HW,CD]
414 Format: { auto | [<io>,][<irq>] }
415
416 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700417 Format:
418 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419
420 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
421 Format: <io>[,<irq>]
422
Randy Dunlapa9913042005-10-23 12:57:11 -0700423 com90xx= [HW,NET]
424 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 Format: <io>[,<irq>[,<memstart>]]
426
427 condev= [HW,S390] console device
428 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 console= [KNL] Output console device and options.
431
432 tty<n> Use the virtual console device <n>.
433
434 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800435 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800437 the form "bbbbpnf", where "bbbb" is the baud rate,
438 "p" is parity ("n", "o", or "e"), "n" is number of
439 bits, and "f" is flow control ("r" for RTS or
440 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800442 See Documentation/serial-console.txt for more
443 information. See
444 Documentation/networking/netconsole.txt for an
445 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446
447 uart,io,<addr>[,options]
448 uart,mmio,<addr>[,options]
449 Start an early, polled-mode console on the 8250/16550
450 UART at the specified I/O port or MMIO address,
451 switching to the matching ttyS device later. The
452 options are the same as for ttyS, above.
453
454 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700455 Format:
456 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457
458 cpia_pp= [HW,PPT]
459 Format: { parport<nr> | auto | none }
460
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700461 crashkernel=nn[KMG]@ss[KMG]
462 [KNL] Reserve a chunk of physical memory to
463 hold a kernel to switch to with kexec on panic.
464
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 cs4232= [HW,OSS]
466 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
467
468 cs89x0_dma= [HW,NET]
469 Format: <dma>
470
471 cs89x0_media= [HW,NET]
472 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700473
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
Randy Dunlapa9913042005-10-23 12:57:11 -0700475
476 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 See header of drivers/s390/block/dasd_devmap.c.
478
479 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
480 (one device per port)
481 Format: <port#>,<type>
482 See also Documentation/input/joystick-parport.txt
483
484 debug [KNL] Enable kernel debugging (events log level).
485
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700486 debug_locks_verbose=
487 [KNL] verbose self-tests
488 Format=<0|1>
489 Print debugging info while doing the locking API
490 self-tests.
491 We default to 0 (no extra messages), setting it to
492 1 will print _a lot_ more information - normally
493 only useful to kernel developers.
494
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 decnet= [HW,NET]
496 Format: <area>[,<node>]
497 See also Documentation/networking/decnet.txt.
498
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 dhash_entries= [KNL]
500 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700501
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 digi= [HW,SERIAL]
503 IO parameters + enable/disable command.
504
505 digiepca= [HW,SERIAL]
506 See drivers/char/README.epca and
507 Documentation/digiepca.txt.
508
509 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
510 support available.
511 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
512
513 dmasound= [HW,OSS] Sound subsystem buffers
514
515 dscc4.setup= [NET]
516
517 dtc3181e= [HW,SCSI]
518
Paul Mundte523d932007-02-28 18:30:01 +0900519 earlyprintk= [IA-32,X86-64,SH]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 earlyprintk=vga
521 earlyprintk=serial[,ttySn[,baudrate]]
522
Randy Dunlapa9913042005-10-23 12:57:11 -0700523 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 takes over.
525
526 Only vga or serial at a time, not both.
527
528 Currently only ttyS0 and ttyS1 are supported.
529
530 Interaction with the standard serial driver is not
531 very good.
532
533 The VGA output is eventually overwritten by the real
534 console.
535
536 eata= [HW,SCSI]
537
Len Brown53f11d42005-12-05 16:46:36 -0500538 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
539 Format: <int>
540 0: polling mode
541 non-0: interrupt mode (default)
542
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 eda= [HW,PS2]
544
545 edb= [HW,PS2]
546
547 edd= [EDD]
548 Format: {"of[f]" | "sk[ipmbr]"}
549 See comment in arch/i386/boot/edd.S
550
Randy Dunlapa9913042005-10-23 12:57:11 -0700551 eicon= [HW,ISDN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 Format: <id>,<membase>,<irq>
553
554 eisa_irq_edge= [PARISC,HW]
555 See header of drivers/parisc/eisa.c.
556
557 elanfreq= [IA-32]
558 See comment before function elanfreq_setup() in
559 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
560
561 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800562 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700563 See Documentation/block/as-iosched.txt and
564 Documentation/block/deadline-iosched.txt for details.
565
Vivek Goyalaac04b32006-01-09 20:51:47 -0800566 elfcorehdr= [IA-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700567 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800568 image elf header. Generally kexec loader will
569 pass this option to capture kernel.
570 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
572 enforcing [SELINUX] Set initial enforcing status.
573 Format: {"0" | "1"}
574 See security/selinux/Kconfig help text.
575 0 -- permissive (log only, no denials).
576 1 -- enforcing (deny and log).
577 Default value is 0.
578 Value can be changed at runtime via /selinux/enforce.
579
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 es1371= [HW,OSS]
581 Format: <spdif>,[<nomix>,[<amplifier>]]
582 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 ether= [HW,NET] Ethernet cards parameters
585 This option is obsoleted by the "netdev=" option, which
586 has equivalent usage. See its documentation for details.
587
588 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
589 Format: <io>[,<irq>]
590
Akinobu Mitade1ba092006-12-08 02:39:42 -0800591 failslab=
592 fail_page_alloc=
593 fail_make_request=[KNL]
594 General fault injection mechanism.
595 Format: <interval>,<probability>,<space>,<times>
596 See also /Documentation/fault-injection/.
597
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 fd_mcs= [HW,SCSI]
599 See header of drivers/scsi/fd_mcs.c.
600
601 fdomain= [HW,SCSI]
602 See header of drivers/scsi/fdomain.c.
603
604 floppy= [HW]
605 See Documentation/floppy.txt.
606
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 gamecon.map[2|3]=
608 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
609 support via parallel port (up to 5 devices per port)
610 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
611 See also Documentation/input/joystick-parport.txt
612
613 gamma= [HW,DRM]
614
615 gdth= [HW,SCSI]
616 See header of drivers/scsi/gdth.c.
617
618 gpt [EFI] Forces disk with valid GPT signature but
619 invalid Protective MBR to be treated as GPT.
620
621 gscd= [HW,CD]
622 Format: <io>
623
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 gvp11= [HW,SCSI]
625
626 hashdist= [KNL,NUMA] Large hashes allocated during boot
627 are distributed across NUMA nodes. Defaults on
628 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700629 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630
631 hcl= [IA-64] SGI's Hardware Graph compatibility layer
632
633 hd= [EIDE] (E)IDE hard drive subsystem geometry
634 Format: <cyl>,<head>,<sect>
635
636 hd?= [HW] (E)IDE subsystem
637 hd?lun= See Documentation/ide.txt.
638
639 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
640 size of <nn>. This works even on boxes that have no
641 highmem otherwise. This also works to reduce highmem
642 size on bigger boxes.
643
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800644 highres= [KNL] Enable/disable high resolution timer mode.
645 Valid parameters: "on", "off"
646 Default: "on"
647
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 hisax= [HW,ISDN]
649 See Documentation/isdn/README.HiSax.
650
651 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
652
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200654 i8042.dumbkbd [HW] Pretend that controller can only read data from
655 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 (Don't attempt to blink the leds)
657 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500658 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 i8042.nomux [HW] Don't check presence of an active multiplexing
660 controller
661 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
662 controllers
663 i8042.panicblink=
664 [HW] Frequency with which keyboard LEDs should blink
665 when kernel panics (default is 0.5 sec)
666 i8042.reset [HW] Reset the controller during init and cleanup
667 i8042.unlock [HW] Unlock (ignore) the keylock
668
669 i810= [HW,DRM]
670
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700671 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
672 indicates that the driver is running on unsupported
673 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
675 does not match list of supported models.
676 i8k.power_status
677 [HW] Report power status in /proc/i8k
678 (disabled by default)
679 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
680 capability is set.
681
682 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
683 See Documentation/mca.txt.
684
685 icn= [HW,ISDN]
686 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
687
688 ide= [HW] (E)IDE subsystem
689 Format: ide=nodma or ide=doubler or ide=reverse
690 See Documentation/ide.txt.
691
692 ide?= [HW] (E)IDE subsystem
693 Format: ide?=noprobe or chipset specific parameters.
694 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700695
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
697 See Documentation/ide.txt.
698
Andi Kleenf039b752007-05-02 19:27:12 +0200699 idle= [X86]
700 Format: idle=poll or idle=mwait
701 Poll forces a polling idle loop that can slightly improves the performance
702 of waking up a idle CPU, but will use a lot of power and make the system
703 run hot. Not recommended.
704 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
705 to not use it because it doesn't save as much power as a normal idle
706 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
707 as idle=poll.
Randy Dunlapa9913042005-10-23 12:57:11 -0700708
Ingo Molnar792908222006-12-06 20:40:51 -0800709 ignore_loglevel [KNL]
710 Ignore loglevel setting - this will print /all/
711 kernel messages to the console. Useful for debugging.
712
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 ihash_entries= [KNL]
714 Set number of hash buckets for inode cache.
715
716 in2000= [HW,SCSI]
717 See header of drivers/scsi/in2000.c.
718
719 init= [KNL]
720 Format: <full_path>
721 Run specified binary instead of /sbin/init as init
722 process.
723
724 initcall_debug [KNL] Trace initcalls as they are executed. Useful
725 for working out where the kernel is dying during
726 startup.
727
728 initrd= [BOOT] Specify the location of the initial ramdisk
729
730 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
731 Format: <irq>
732
Jesse Barnes2bd0fa32005-12-13 03:05:03 -0500733 combined_mode= [HW] control which driver uses IDE ports in combined
734 mode: legacy IDE driver, libata, or both
735 (in the libata case, libata.atapi_enabled=1 may be
736 useful as well). Note that using the ide or libata
737 options may affect your device naming (e.g. by
738 changing hdc to sdb).
739 Format: combined (default), ide, or libata
740
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 inttest= [IA64]
742
743 io7= [HW] IO7 for Marvel based alpha systems
744 See comment before marvel_specify_io7 in
745 arch/alpha/kernel/core_marvel.c.
746
747 ip= [IP_PNP]
748 See Documentation/nfsroot.txt.
749
750 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
751 See comment before ip2_setup() in drivers/char/ip2.c.
752
753 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
754 See header of drivers/scsi/ips.c.
755
Simon Horman72c4a132006-09-13 19:57:18 -0700756 ports= [IP_VS_FTP] IPVS ftp helper module
757 Default is 21.
758 Up to 8 (IP_VS_APP_MAX_PORTS) ports
759 may be specified.
760 Format: <port>,<port>....
761
Alan Cox200803d2005-06-28 20:45:18 -0700762 irqfixup [HW]
763 When an interrupt is not handled search all handlers
764 for it. Intended to get systems with badly broken
765 firmware running.
766
767 irqpoll [HW]
768 When an interrupt is not handled search all handlers
769 for it. Also check all handlers each timer
770 interrupt. Intended to get systems with badly broken
771 firmware running.
772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700774 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775
776 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800777 Format:
778 <cpu number>,...,<cpu number>
779 or
780 <cpu number>-<cpu number> (must be a positive range in ascending order)
781 or a mixture
782 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 This option can be used to specify one or more CPUs
784 to isolate from the general SMP balancing and scheduling
785 algorithms. The only way to move a process onto or off
786 an "isolated" CPU is via the CPU affinity syscalls.
787 <cpu number> begins at 0 and the maximum value is
788 "number of CPUs in system - 1".
789
790 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700791 alternative -- manually setting the CPU mask of all
792 tasks in the system -- can cause problems and
793 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794
795 isp16= [HW,CD]
796 Format: <io>,<irq>,<dma>,<setup>
797
Randy Dunlapa9913042005-10-23 12:57:11 -0700798 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799
800 js= [HW,JOY] Analog joystick
801 See Documentation/input/joystick.txt.
802
803 keepinitrd [HW,ARM]
804
Randy Dunlapa9913042005-10-23 12:57:11 -0700805 kstack=N [IA-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 in oops dumps.
807
808 l2cr= [PPC]
809
Randy Dunlapa9913042005-10-23 12:57:11 -0700810 lapic [IA-32,APIC] Enable the local APIC even if BIOS
811 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
Linus Torvalds2e7c2832007-03-23 11:32:31 -0700813 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +0100814 C2 power state.
815
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
817 Format: addr:<io>,irq:<irq>
818
Randy Dunlapa9913042005-10-23 12:57:11 -0700819 llsc*= [IA64] See function print_params() in
820 arch/ia64/sn/kernel/llsc4.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821
822 load_ramdisk= [RAM] List of ramdisks to load from floppy
823 See Documentation/ramdisk.txt.
824
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800825 lockd.nlm_grace_period=P [NFS] Assign grace period.
826 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800828 lockd.nlm_tcpport=N [NFS] Assign TCP port.
829 Format: <integer>
830
831 lockd.nlm_timeout=T [NFS] Assign timeout value.
832 Format: <integer>
833
834 lockd.nlm_udpport=M [NFS] Assign UDP port.
835 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836
837 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
838 Format: <irq>
839
840 loglevel= All Kernel Messages with a loglevel smaller than the
841 console loglevel will be printed to the console. It can
842 also be changed with klogd or other programs. The
843 loglevels are defined as follows:
844
845 0 (KERN_EMERG) system is unusable
846 1 (KERN_ALERT) action must be taken immediately
847 2 (KERN_CRIT) critical conditions
848 3 (KERN_ERR) error conditions
849 4 (KERN_WARNING) warning conditions
850 5 (KERN_NOTICE) normal but significant condition
851 6 (KERN_INFO) informational
852 7 (KERN_DEBUG) debug-level messages
853
854 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700855 Format: { n | nk | nM }
856 n must be a power of two. The default size
857 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858
859 lp=0 [LP] Specify parallel ports to use, e.g,
860 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
861 lp=reset first parallel port). 'lp=0' disables the
862 lp=auto printer driver. 'lp=reset' (which can be
863 specified in addition to the ports) causes
864 attached printers to be reset. Using
865 lp=port1,port2,... specifies the parallel ports
866 to associate lp devices with, starting with
867 lp0. A port specification may be 'none' to skip
868 that lp device, or a parport name such as
869 'parport0'. Specifying 'lp=auto' instead of a
870 port specification list means that device IDs
871 from each port should be examined, to see if
872 an IEEE 1284-compliant printer is attached; if
873 so, the driver will manage that printer.
874 See also header of drivers/char/lp.c.
875
876 lpj=n [KNL]
877 Sets loops_per_jiffy to given constant, thus avoiding
878 time-consuming boot-time autodetection (up to 250 ms per
879 CPU). 0 enables autodetection (default). To determine
880 the correct value for your kernel, boot with normal
881 autodetection and see what value is printed. Note that
882 on SMP systems the preset will be applied to all CPUs,
883 which is likely to cause problems if your CPUs need
884 significantly divergent settings. An incorrect value
885 will cause delays in the kernel to be wrong, leading to
886 unpredictable I/O errors and other breakage. Although
887 unlikely, in the extreme case this might damage your
888 hardware.
889
890 ltpc= [NET]
891 Format: <io>,<irq>,<dma>
892
Randy Dunlapa9913042005-10-23 12:57:11 -0700893 mac5380= [HW,SCSI] Format:
894 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895
Randy Dunlapa9913042005-10-23 12:57:11 -0700896 mac53c9x= [HW,SCSI] Format:
897 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898
Randy Dunlapa9913042005-10-23 12:57:11 -0700899 machvec= [IA64] Force the use of a particular machine-vector
900 (machvec) in a generic kernel.
901 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902
Randy Dunlapa9913042005-10-23 12:57:11 -0700903 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 be mounted
905 Format: <1-256>
906
907 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Randy Dunlap78f92a82007-02-17 19:58:30 +0100908 should make use of.
909 Using "nosmp" or "maxcpus=0" will disable SMP
910 entirely (the MPS table probe still happens, though).
911 A command-line option of "maxcpus=<NUM>", where <NUM>
912 is an integer greater than 0, limits the maximum number
913 of CPUs activated in SMP mode to <NUM>.
914 Using "maxcpus=1" on an SMP kernel is the trivial
915 case of an SMP kernel with only one CPU.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916
Bob Picco2b2c3752005-06-29 18:00:00 -0700917 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
918 equal to this physical address is ignored.
919
Randy Dunlapa9913042005-10-23 12:57:11 -0700920 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 Should be between 1 and 2^32-1.
922
923 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -0700924 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 Should be between 1 and 16384.
926
927 mca-pentium [BUGS=IA-32]
928
929 mcatest= [IA-64]
930
931 mcd= [HW,CD]
932 Format: <port>,<irq>,<mitsumi_bug_93_wait>
933
934 mcdx= [HW,CD]
935
936 mce [IA-32] Machine Check Exception
937
938 md= [HW] RAID subsystems devices and level
939 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700940
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 mdacon= [MDA]
942 Format: <first>,<last>
943 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -0700944
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
946 Amount of memory to be used when the kernel is not able
947 to see the whole system memory or for test.
948 [IA-32] Use together with memmap= to avoid physical
949 address space collisions. Without memmap= PCI devices
950 could be placed at addresses belonging to unused RAM.
951
952 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
953 memory.
954
akpm@osdl.org69cda7b2006-01-09 20:51:46 -0800955 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 E820 memory map, as specified by the user.
957 Such memmap=exactmap lines can be constructed based on
958 BIOS output or other requirements. See the memmap=nn@ss
959 option description.
960
961 memmap=nn[KMG]@ss[KMG]
962 [KNL] Force usage of a specific region of memory
963 Region of memory to be used, from ss to ss+nn.
964
965 memmap=nn[KMG]#ss[KMG]
966 [KNL,ACPI] Mark specific memory as ACPI data.
967 Region of memory to be used, from ss to ss+nn.
968
969 memmap=nn[KMG]$ss[KMG]
970 [KNL,ACPI] Mark specific memory as reserved.
971 Region of memory to be used, from ss to ss+nn.
972
973 meye.*= [HW] Set MotionEye Camera parameters
974 See Documentation/video4linux/meye.txt.
975
976 mga= [HW,DRM]
977
akpm@osdl.org198e2f12006-01-12 01:05:30 -0800978 migration_cost=
979 [KNL,SMP] debug: override scheduler migration costs
980 Format: <level-1-usecs>,<level-2-usecs>,...
981 This debugging option can be used to override the
982 default scheduler migration cost matrix. The numbers
983 are indexed by 'CPU domain distance'.
984 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
985 box will set up an intra-core migration cost of
986 1 msec, an inter-core migration cost of 2 msecs,
987 and an inter-node migration cost of 3 msecs.
988
989 WARNING: using the wrong values here can break
990 scheduler performance, so it's only for scheduler
991 development purposes, not production environments.
992
993 migration_debug=
994 [KNL,SMP] migration cost auto-detect verbosity
995 Format=<0|1|2>
996 If a system's migration matrix reported at bootup
997 seems erroneous then this option can be used to
998 increase verbosity of the detection process.
999 We default to 0 (no extra messages), 1 will print
1000 some more information, and 2 will be really
1001 verbose (probably only useful if you also have a
1002 serial console attached to the system).
1003
1004 migration_factor=
1005 [KNL,SMP] multiply/divide migration costs by a factor
1006 Format=<percent>
1007 This debug option can be used to proportionally
1008 increase or decrease the auto-detected migration
1009 costs for all entries of the migration matrix.
1010 E.g. migration_factor=150 will increase migration
1011 costs by 50%. (and thus the scheduler will be less
1012 eager migrating cache-hot tasks)
1013 migration_factor=80 will decrease migration costs
1014 by 20%. (thus the scheduler will be more eager to
1015 migrate tasks)
1016
1017 WARNING: using the wrong values here can break
1018 scheduler performance, so it's only for scheduler
1019 development purposes, not production environments.
1020
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 mousedev.tap_time=
1022 [MOUSE] Maximum time between finger touching and
1023 leaving touchpad surface for touch to be considered
1024 a tap and be reported as a left button click (for
1025 touchpads working in absolute mode only).
1026 Format: <msecs>
1027 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1028 reporting absolute coordinates, such as tablets
1029 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1030 reporting absolute coordinates, such as tablets
1031
1032 mpu401= [HW,OSS]
1033 Format: <io>,<irq>
1034
1035 MTD_Partition= [MTD]
1036 Format: <name>,<region-number>,<size>,<offset>
1037
Randy Dunlapa9913042005-10-23 12:57:11 -07001038 MTD_Region= [MTD] Format:
1039 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040
1041 mtdparts= [MTD]
1042 See drivers/mtd/cmdline.c.
1043
1044 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001045 [HW] Make the MicroTouch USB driver use raw coordinates
1046 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047
1048 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1049
1050 NCR_D700= [HW,SCSI]
1051 See header of drivers/scsi/NCR_D700.c.
1052
1053 ncr5380= [HW,SCSI]
1054
1055 ncr53c400= [HW,SCSI]
1056
1057 ncr53c400a= [HW,SCSI]
1058
1059 ncr53c406a= [HW,SCSI]
1060
1061 ncr53c8xx= [HW,SCSI]
1062
1063 netdev= [NET] Network devices parameters
1064 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1065 Note that mem_start is often overloaded to mean
1066 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001067 This usage is only documented in each driver source
1068 file if at all.
1069
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 nfsaddrs= [NFS]
1071 See Documentation/nfsroot.txt.
1072
1073 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1074 See Documentation/nfsroot.txt.
1075
Trond Myklebusta72b4422006-01-03 09:55:41 +01001076 nfs.callback_tcpport=
1077 [NFS] set the TCP port on which the NFSv4 callback
1078 channel should listen.
1079
Trond Myklebust58df0952006-01-03 09:55:57 +01001080 nfs.idmap_cache_timeout=
1081 [NFS] set the maximum lifetime for idmapper cache
1082 entries.
1083
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1085
1086 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1087 emulation library even if a 387 maths coprocessor
1088 is present.
1089
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -07001090 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1091 when set.
1092 Format: <int>
1093
Paul Menage3395ee02006-12-06 20:32:16 -08001094 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1095 the slab allocator. Saves per-node memory, but will
1096 impact performance on real NUMA hardware.
1097
Randy Dunlapa9913042005-10-23 12:57:11 -07001098 noalign [KNL,ARM]
1099
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 noapic [SMP,APIC] Tells the kernel to not make use of any
1101 IOAPICs that may be present in the system.
1102
1103 noasync [HW,M68K] Disables async and sync negotiation for
1104 all devices.
1105
1106 nobats [PPC] Do not use BATs for mapping kernel lowmem
1107 on "Classic" PPC cores.
1108
1109 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001110
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001111 nodelayacct [KNL] Disable per-task delay accounting
1112
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1114
1115 noexec [IA-64]
1116
Randy Dunlapa9913042005-10-23 12:57:11 -07001117 noexec [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 noexec=on: enable non-executable mappings (default)
1119 noexec=off: disable nn-executable mappings
1120
Chuck Ebbert4f886512006-03-23 02:59:34 -08001121 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1122 register save and restore. The kernel will only save
1123 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
1125 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001126
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1128 instruction doesn't work correctly and not to
1129 use it.
1130
1131 nohalt [IA-64] Tells the kernel not to use the power saving
1132 function PAL_HALT_LIGHT when idle. This increases
1133 power-consumption. On the positive side, it reduces
1134 interrupt wake-up latency, which may improve performance
1135 in certain environments such as networked servers or
1136 real-time systems.
1137
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001138 nohz= [KNL] Boottime enable/disable dynamic ticks
1139 Valid arguments: on, off
1140 Default: on
1141
Zachary Amsden8542b202006-12-07 02:14:09 +01001142 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1143
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144 noirqdebug [IA-32] Disables the code which attempts to detect and
1145 disable unhandled interrupt sources.
1146
Zachary Amsden8542b202006-12-07 02:14:09 +01001147 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1148 broken timer IRQ sources.
1149
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150 noisapnp [ISAPNP] Disables ISA PnP code.
1151
1152 noinitrd [RAM] Tells the kernel not to load any configured
1153 initial RAM disk.
1154
1155 nointroute [IA-64]
1156
1157 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1158
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001159 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1160
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 noltlbs [PPC] Do not use large page/tlb entries for kernel
1162 lowmem mapping on PPC40x.
1163
Horms312f1f02006-02-22 09:57:55 +09001164 nomca [IA-64] Disable machine check abort handling
1165
Hormsabe37e52006-04-01 01:36:09 +02001166 nomce [IA-32] Machine Check Exception
1167
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001168 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1169
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001170 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1171 with UP alternatives
1172
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 noresidual [PPC] Don't use residual data on PReP machines.
1174
Randy Dunlapa9913042005-10-23 12:57:11 -07001175 noresume [SWSUSP] Disables resume and restores original swap
1176 space.
1177
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 no-scroll [VGA] Disables scrollback.
1179 This is required for the Braillex ib80-piezo Braille
1180 reader made by F.H. Papenmeier (Germany).
1181
1182 nosbagart [IA-64]
1183
Chuck Ebbert4f886512006-03-23 02:59:34 -08001184 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1185
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1187
1188 nosync [HW,M68K] Disables sync negotiation for all devices.
1189
1190 notsc [BUGS=IA-32] Disable Time Stamp Counter
1191
1192 nousb [USB] Disable the USB subsystem
1193
1194 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001195
Dave Jonesa61c2d72006-01-07 23:18:19 +00001196 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1197
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 opl3= [HW,OSS]
1199 Format: <io>
1200
Randy Dunlapa9913042005-10-23 12:57:11 -07001201 opl3sa2= [HW,OSS] Format:
1202 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1203
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 oprofile.timer= [HW]
1205 Use timer interrupt instead of performance counters
1206
1207 optcd= [HW,CD]
1208 Format: <io>
1209
1210 osst= [HW,SCSI] SCSI Tape Driver
1211 Format: <buffer_size>,<write_threshold>
1212 See also Documentation/scsi/st.txt.
1213
1214 panic= [KNL] Kernel behaviour on panic
1215 Format: <timeout>
1216
1217 parkbd.port= [HW] Parallel port number the keyboard adapter is
1218 connected to, default is 0.
1219 Format: <parport#>
1220 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1221 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001222 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223
Randy Dunlapa9913042005-10-23 12:57:11 -07001224 parport= [HW,PPT] Specify parallel ports. 0 disables.
1225 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1226 Use 'auto' to force the driver to use any
1227 IRQ/DMA settings detected (the default is to
1228 ignore detected IRQ/DMA settings because of
1229 possible conflicts). You can specify the base
1230 address, IRQ, and DMA settings; IRQ and DMA
1231 should be numbers, or 'auto' (for using detected
1232 settings on that particular port), or 'nofifo'
1233 (to avoid using a FIFO even if it is detected).
1234 Parallel ports are assigned in the order they
1235 are specified on the command line, starting
1236 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
Randy Dunlapa9913042005-10-23 12:57:11 -07001238 parport_init_mode= [HW,PPT]
1239 Configure VIA parallel port to operate in
1240 a specific mode. This is necessary on Pegasos
1241 computer where firmware has no options for setting
1242 up parallel port mode and sets it to spp.
1243 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 Format: [spp|ps2|epp|ecp|ecpepp]
1245
Randy Dunlapa9913042005-10-23 12:57:11 -07001246 pas2= [HW,OSS] Format:
1247 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1248
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249 pas16= [HW,SCSI]
1250 See header of drivers/scsi/pas16.c.
1251
Andrew Mortondd287792006-03-23 03:00:57 -08001252 pause_on_oops=
1253 Halt all CPUs after the first oops has been printed for
1254 the specified number of seconds. This is to be used if
1255 your oopses keep scrolling off the screen.
1256
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 pcbit= [HW,ISDN]
1258
1259 pcd. [PARIDE]
1260 See header of drivers/block/paride/pcd.c.
1261 See also Documentation/paride.txt.
1262
Randy Dunlapa9913042005-10-23 12:57:11 -07001263 pci=option[,option...] [PCI] various PCI subsystem options:
1264 off [IA-32] don't probe for the PCI bus
1265 bios [IA-32] force use of PCI BIOS, don't access
1266 the hardware directly. Use this if your machine
1267 has a non-standard PCI host bridge.
1268 nobios [IA-32] disallow use of PCI BIOS, only direct
1269 hardware access methods are allowed. Use this
1270 if you experience crashes upon bootup and you
1271 suspect they are caused by the BIOS.
1272 conf1 [IA-32] Force use of PCI Configuration
1273 Mechanism 1.
1274 conf2 [IA-32] Force use of PCI Configuration
1275 Mechanism 2.
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001276 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1277 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001278 nomsi [MSI] If the PCI_MSI kernel config parameter is
1279 enabled, this kernel boot option can be used to
1280 disable the use of MSI interrupts system-wide.
Randy Dunlapa9913042005-10-23 12:57:11 -07001281 nosort [IA-32] Don't sort PCI devices according to
1282 order given by the PCI BIOS. This sorting is
1283 done to get a device order compatible with
1284 older kernels.
1285 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1286 routing table. These calls are known to be buggy
1287 on several machines and they hang the machine
1288 when used, but on other computers it's the only
1289 way to get the interrupt routing table. Try
1290 this option if the kernel is unable to allocate
1291 IRQs or discover secondary PCI buses on your
1292 motherboard.
1293 rom [IA-32] Assign address space to expansion ROMs.
1294 Use with caution as certain devices share
1295 address decoders between ROMs and other
1296 resources.
1297 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1298 assigned automatically to PCI devices. You can
1299 make the kernel exclude IRQs of your ISA cards
1300 this way.
jayalk@intworks.biz120bb422005-03-21 20:20:42 -08001301 pirqaddr=0xAAAAA [IA-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001302 of the PIRQ table (normally generated
1303 by the BIOS) if it is outside the
1304 F0000h-100000h range.
1305 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1306 useful if the kernel is unable to find your
1307 secondary buses and you want to tell it
1308 explicitly which ones they are.
1309 assign-busses [IA-32] Always assign all PCI bus
1310 numbers ourselves, overriding
1311 whatever the firmware may have done.
1312 usepirqmask [IA-32] Honor the possible IRQ mask stored
1313 in the BIOS $PIR table. This is needed on
1314 some systems with broken BIOSes, notably
1315 some HP Pavilion N5400 and Omnibook XE3
1316 notebooks. This will have no effect if ACPI
1317 IRQ routing is enabled.
1318 noacpi [IA-32] Do not use ACPI for IRQ routing
1319 or for PCI scanning.
1320 routeirq Do IRQ routing for all PCI devices.
1321 This is normally done in pci_enable_device(),
1322 so this option is a temporary workaround
1323 for broken drivers that don't call it.
1324 firmware [ARM] Do not re-enumerate the bus but instead
1325 just use the configuration from the
1326 bootloader. This is currently used on
1327 IXP2000 systems where the bus has to be
1328 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001329 noearly [X86] Don't do any early type 1 scanning.
1330 This might help on some broken boards which
1331 machine check when some devices' config space
1332 is read. But various workarounds are disabled
1333 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001334 bfsort Sort PCI devices into breadth-first order.
1335 This sorting is done to get a device
1336 order compatible with older (<= 2.4) kernels.
1337 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001338 cbiosize=nn[KMG] The fixed amount of bus space which is
1339 reserved for the CardBus bridge's IO window.
1340 The default value is 256 bytes.
1341 cbmemsize=nn[KMG] The fixed amount of bus space which is
1342 reserved for the CardBus bridge's memory
1343 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001344
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 pcmv= [HW,PCMCIA] BadgePAD 4
1346
1347 pd. [PARIDE]
1348 See Documentation/paride.txt.
1349
1350 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1351 boot time.
1352 Format: { 0 | 1 }
1353 See arch/parisc/kernel/pdc_chassis.c
1354
1355 pf. [PARIDE]
1356 See Documentation/paride.txt.
1357
1358 pg. [PARIDE]
1359 See Documentation/paride.txt.
1360
1361 pirq= [SMP,APIC] Manual mp-table setup
1362 See Documentation/i386/IO-APIC.txt.
1363
1364 plip= [PPT,NET] Parallel port network link
1365 Format: { parport<nr> | timid | 0 }
1366 See also Documentation/parport.txt.
1367
1368 pnpacpi= [ACPI]
1369 { off }
1370
1371 pnpbios= [ISAPNP]
1372 { on | off | curr | res | no-curr | no-res }
1373
1374 pnp_reserve_irq=
1375 [ISAPNP] Exclude IRQs for the autoconfiguration
1376
1377 pnp_reserve_dma=
1378 [ISAPNP] Exclude DMAs for the autoconfiguration
1379
1380 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001381 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382
1383 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001384 [ISAPNP] Exclude memory regions for the
1385 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 Ranges are in pairs (memory base and size).
1387
1388 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001389 Format: [schedule,]<number>
1390 Param: "schedule" - profile schedule points.
1391 Param: <number> - step/bucket size as a power of 2 for
1392 statistical time based profiling.
Ingo Molnarece8a682006-12-06 20:37:24 -08001393 Param: "sleep" - profile D-state sleeping (millisecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394
Randy Dunlapa9913042005-10-23 12:57:11 -07001395 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 Limit processor to maximum C-state
1397 max_cstate=9 overrides any DMI blacklist limit.
1398
Len Brown41c0d862005-12-28 12:43:51 -05001399 processor.nocst [HW,ACPI]
1400 Ignore the _CST method to determine C-states,
1401 instead using the legacy FADT method
1402
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1404 before loading.
1405 See Documentation/ramdisk.txt.
1406
Randy Dunlapa9913042005-10-23 12:57:11 -07001407 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1408 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1410 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001411 psmouse.resetafter= [HW,MOUSE]
1412 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 (0 = never).
1414 psmouse.resolution=
1415 [HW,MOUSE] Set desired mouse resolution, in dpi.
1416 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001417 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 0 = disabled, 1 = enabled (default).
1419
1420 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001421 Format:
1422 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423
1424 pt. [PARIDE]
1425 See Documentation/paride.txt.
1426
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001427 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001428
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 r128= [HW,DRM]
1430
1431 raid= [HW,RAID]
1432 See Documentation/md.txt.
1433
1434 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1435 See Documentation/ramdisk.txt.
1436
Randy Dunlapa9913042005-10-23 12:57:11 -07001437 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001439
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1441 New name for the ramdisk parameter.
1442 See Documentation/ramdisk.txt.
1443
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001444 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1445 RCU callbacks to process in one batch.
1446
1447 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1448 RCU callbacks over which batch limiting is disabled.
1449
1450 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1451 RCU callbacks below which batch limiting is re-enabled.
1452
Olof Johanssonffdfc402005-09-06 15:17:19 -07001453 rdinit= [KNL]
1454 Format: <full_path>
1455 Run specified binary instead of /init from the ramdisk,
1456 used for early userspace startup. See initrd.
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1459 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Michael Opdenackerf3e299f2006-10-03 23:19:24 +02001460 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461
1462 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1463
Zachary Amsden461a9aff2006-09-25 23:32:25 -07001464 reservetop= [IA-32]
1465 Format: nn[KMG]
1466 Reserves a hole at the top of the kernel virtual
1467 address space.
1468
Vivek Goyal7e962872006-09-27 01:50:44 -07001469 reset_devices [KNL] Force drivers to reset the underlying device
1470 during initialization.
1471
Randy Dunlapa9913042005-10-23 12:57:11 -07001472 resume= [SWSUSP]
1473 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001475 resume_offset= [SWSUSP]
1476 Specify the offset from the beginning of the partition
1477 given by "resume=" at which the swap header is located,
1478 in <PAGE_SIZE> units (needed only for swap files).
1479 See Documentation/power/swsusp-and-swap-files.txt
1480
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001481 retain_initrd [RAM] Keep initrd memory after extraction
1482
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 rhash_entries= [KNL,NET]
1484 Set number of hash buckets for route cache
1485
1486 riscom8= [HW,SERIAL]
1487 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1488
1489 ro [KNL] Mount root device read-only on boot
1490
1491 root= [KNL] Root filesystem
1492
1493 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1494 mount the root filesystem
1495
1496 rootflags= [KNL] Set root filesystem mount option string
1497
1498 rootfstype= [KNL] Set root filesystem type
1499
1500 rw [KNL] Mount root device read-write on boot
1501
1502 S [KNL] Run init in single mode
1503
1504 sa1100ir [NET]
1505 See drivers/net/irda/sa1100_ir.c.
1506
1507 sb= [HW,OSS]
1508 Format: <io>,<irq>,<dma>,<dma2>
1509
1510 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 sbpcd= [HW,CD] Soundblaster CD adapter
1513 Format: <io>,<type>
1514 See a comment before function sbpcd_setup() in
1515 drivers/cdrom/sbpcd.c.
1516
1517 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1518 Format: <io>[,<timeout>[,<isapnp>]]
1519
1520 scsi_debug_*= [SCSI]
1521 See drivers/scsi/scsi_debug.c.
1522
1523 scsi_default_dev_flags=
1524 [SCSI] SCSI default device flags
1525 Format: <integer>
1526
1527 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1528 Format: <vendor>:<model>:<flags>
1529 (flags are integer value)
1530
1531 scsi_logging= [SCSI]
1532
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001533 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1534 discovered. async scans them in kernel threads,
1535 allowing boot to proceed. none ignores them, expecting
1536 user space to do the scan.
1537
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 selinux [SELINUX] Disable or enable SELinux at boot time.
1539 Format: { "0" | "1" }
1540 See security/selinux/Kconfig help text.
1541 0 -- disable.
1542 1 -- enable.
1543 Default value is set via kernel config option.
1544 If enabled at boot time, /selinux/disable can be used
1545 later to disable prior to initial policy load.
1546
James Morris4e5ab4c2006-06-09 00:33:33 -07001547 selinux_compat_net =
1548 [SELINUX] Set initial selinux_compat_net flag value.
1549 Format: { "0" | "1" }
1550 0 -- use new secmark-based packet controls
1551 1 -- use legacy packet controls
1552 Default value is 0 (preferred).
1553 Value can be changed at runtime via
1554 /selinux/compat_net.
1555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 serialnumber [BUGS=IA-32]
1557
Randy Dunlapa9913042005-10-23 12:57:11 -07001558 sg_def_reserved_size= [SCSI]
1559
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 shapers= [NET]
1561 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001562
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563 sim710= [SCSI,HW]
1564 See header of drivers/scsi/sim710.c.
1565
1566 simeth= [IA-64]
1567 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001568
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 sjcd= [HW,CD]
1570 Format: <io>,<irq>,<dma>
1571 See header of drivers/cdrom/sjcd.c.
1572
1573 slram= [HW,MTD]
1574
1575 smart2= [HW]
1576 Format: <io1>[,<io2>[,...,<io8>]]
1577
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001578 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1579 attempt to substitute SMP alternatives once at boot.
1580
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001581 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1582 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1583 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1584 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1585 smsc-ircc2.ircc_irq= [HW] IRQ line
1586 smsc-ircc2.ircc_dma= [HW] DMA channel
1587 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1588 0: Toshiba Satellite 1800 (GP data pin select)
1589 1: Fast pin select (default)
1590 2: ATC IRMode
1591
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 snd-ad1816a= [HW,ALSA]
1593
1594 snd-ad1848= [HW,ALSA]
1595
1596 snd-ali5451= [HW,ALSA]
1597
1598 snd-als100= [HW,ALSA]
1599
1600 snd-als4000= [HW,ALSA]
1601
1602 snd-azt2320= [HW,ALSA]
1603
1604 snd-cmi8330= [HW,ALSA]
1605
1606 snd-cmipci= [HW,ALSA]
1607
1608 snd-cs4231= [HW,ALSA]
1609
1610 snd-cs4232= [HW,ALSA]
1611
1612 snd-cs4236= [HW,ALSA]
1613
1614 snd-cs4281= [HW,ALSA]
1615
1616 snd-cs46xx= [HW,ALSA]
1617
1618 snd-dt019x= [HW,ALSA]
1619
1620 snd-dummy= [HW,ALSA]
1621
1622 snd-emu10k1= [HW,ALSA]
1623
1624 snd-ens1370= [HW,ALSA]
1625
1626 snd-ens1371= [HW,ALSA]
1627
1628 snd-es968= [HW,ALSA]
1629
1630 snd-es1688= [HW,ALSA]
1631
1632 snd-es18xx= [HW,ALSA]
1633
1634 snd-es1938= [HW,ALSA]
1635
1636 snd-es1968= [HW,ALSA]
1637
1638 snd-fm801= [HW,ALSA]
1639
1640 snd-gusclassic= [HW,ALSA]
1641
1642 snd-gusextreme= [HW,ALSA]
1643
1644 snd-gusmax= [HW,ALSA]
1645
1646 snd-hdsp= [HW,ALSA]
1647
1648 snd-ice1712= [HW,ALSA]
1649
1650 snd-intel8x0= [HW,ALSA]
1651
1652 snd-interwave= [HW,ALSA]
1653
1654 snd-interwave-stb=
1655 [HW,ALSA]
1656
1657 snd-korg1212= [HW,ALSA]
1658
1659 snd-maestro3= [HW,ALSA]
1660
1661 snd-mpu401= [HW,ALSA]
1662
1663 snd-mtpav= [HW,ALSA]
1664
1665 snd-nm256= [HW,ALSA]
1666
1667 snd-opl3sa2= [HW,ALSA]
1668
1669 snd-opti92x-ad1848=
1670 [HW,ALSA]
1671
1672 snd-opti92x-cs4231=
1673 [HW,ALSA]
1674
1675 snd-opti93x= [HW,ALSA]
1676
1677 snd-pmac= [HW,ALSA]
1678
1679 snd-rme32= [HW,ALSA]
1680
1681 snd-rme96= [HW,ALSA]
1682
1683 snd-rme9652= [HW,ALSA]
1684
1685 snd-sb8= [HW,ALSA]
1686
1687 snd-sb16= [HW,ALSA]
1688
1689 snd-sbawe= [HW,ALSA]
1690
1691 snd-serial= [HW,ALSA]
1692
1693 snd-sgalaxy= [HW,ALSA]
1694
1695 snd-sonicvibes= [HW,ALSA]
1696
1697 snd-sun-amd7930=
1698 [HW,ALSA]
1699
1700 snd-sun-cs4231= [HW,ALSA]
1701
1702 snd-trident= [HW,ALSA]
1703
1704 snd-usb-audio= [HW,ALSA,USB]
1705
1706 snd-via82xx= [HW,ALSA]
1707
1708 snd-virmidi= [HW,ALSA]
1709
1710 snd-wavefront= [HW,ALSA]
1711
1712 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001713
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 sonycd535= [HW,CD]
1715 Format: <io>[,<irq>]
1716
1717 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1718 See Documentation/sonypi.txt
1719
1720 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1721 See Documentation/specialix.txt.
1722
1723 spia_io_base= [HW,MTD]
1724 spia_fio_base=
1725 spia_pedr=
1726 spia_peddr=
1727
1728 sscape= [HW,OSS]
1729 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001730
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1732 See Documentation/scsi/st.txt.
1733
1734 st0x= [HW,SCSI]
1735 See header of drivers/scsi/seagate.c.
1736
1737 sti= [PARISC,HW]
1738 Format: <num>
1739 Set the STI (builtin display/keyboard on the HP-PARISC
1740 machines) console (graphic card) which should be used
1741 as the initial boot-console.
1742 See also comment in drivers/video/console/sticore.c.
1743
1744 sti_font= [HW]
1745 See comment in drivers/video/console/sticore.c.
1746
1747 stifb= [HW]
1748 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1749
Greg Banks42a7fc42007-03-06 01:42:23 -08001750 sunrpc.pool_mode=
1751 [NFS]
1752 Control how the NFS server code allocates CPUs to
1753 service thread pools. Depending on how many NICs
1754 you have and where their interrupts are bound, this
1755 option will affect which CPUs will do NFS serving.
1756 Note: this parameter cannot be changed while the
1757 NFS server is running.
1758
1759 auto the server chooses an appropriate mode
1760 automatically using heuristics
1761 global a single global pool contains all CPUs
1762 percpu one pool for each CPU
1763 pernode one pool for each NUMA node (equivalent
1764 to global on non-NUMA machines)
1765
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 switches= [HW,M68k]
1769
1770 sym53c416= [HW,SCSI]
1771 See header of drivers/scsi/sym53c416.c.
1772
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001773 sysrq_always_enabled
1774 [KNL]
1775 Ignore sysrq setting - this boot parameter will
1776 neutralize any effect of /proc/sys/kernel/sysrq.
1777 Useful for debugging.
1778
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 t128= [HW,SCSI]
1780 See header of drivers/scsi/t128.c.
1781
1782 tdfx= [HW,DRM]
1783
1784 thash_entries= [KNL,NET]
1785 Set number of hash buckets for TCP connection
1786
1787 time Show timing data prefixed to each printk message line
1788
john stultz734efb42006-06-26 00:25:05 -07001789 clocksource= [GENERIC_TIME] Override the default clocksource
1790 Override the default clocksource and use the clocksource
1791 with the name specified.
1792
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 tipar.timeout= [HW,PPT]
1794 Set communications timeout in tenths of a second
1795 (default 15).
1796
1797 tipar.delay= [HW,PPT]
1798 Set inter-bit delay in microseconds (default 10).
1799
1800 tmc8xx= [HW,SCSI]
1801 See header of drivers/scsi/seagate.c.
1802
1803 tmscsim= [HW,SCSI]
1804 See comment before function dc390_setup() in
1805 drivers/scsi/tmscsim.c.
1806
1807 tp720= [HW,PS2]
1808
1809 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001810 Format:
1811 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1812
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 tsdev.xres= [TS] Horizontal screen resolution.
1814 tsdev.yres= [TS] Vertical screen resolution.
1815
Randy Dunlapa9913042005-10-23 12:57:11 -07001816 turbografx.map[2|3]= [HW,JOY]
1817 TurboGraFX parallel port interface
1818 Format:
1819 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820 See also Documentation/input/joystick-parport.txt
1821
1822 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1823 See header of drivers/scsi/u14-34f.c.
1824
1825 uart401= [HW,OSS]
1826 Format: <io>,<irq>
1827
1828 uart6850= [HW,OSS]
1829 Format: <io>,<irq>
1830
Alan Stern5f8364b2006-12-05 16:29:55 -05001831 uhci-hcd.ignore_oc=
1832 [USB] Ignore overcurrent events (default N).
1833 Some badly-designed motherboards generate lots of
1834 bogus events, for ports that aren't wired to
1835 anything. Set this parameter to avoid log spamming.
1836 Note that genuine overcurrent events won't be
1837 reported either.
1838
Alan Sternb5e795f2007-02-20 15:00:53 -05001839 usbcore.autosuspend=
1840 [USB] The autosuspend time delay (in seconds) used
1841 for newly-detected USB devices (default 2). This
1842 is the time required before an idle device will be
1843 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04001844 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05001845
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846 usbhid.mousepoll=
1847 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07001848
Paul Mundte523d932007-02-28 18:30:01 +09001849 vdso= [IA-32,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02001850 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07001851 vdso=1: enable VDSO (default)
1852 vdso=0: disable VDSO mapping
1853
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 video= [FB] Frame buffer configuration
1855 See Documentation/fb/modedb.txt.
1856
1857 vga= [BOOT,IA-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07001858 See Documentation/i386/boot.txt and
1859 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860 Use vga=ask for menu.
1861 This is actually a boot loader parameter; the value is
1862 passed to the kernel using a special protocol.
1863
Randy Dunlapa9913042005-10-23 12:57:11 -07001864 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 size of <nn>. This can be used to increase the
1866 minimum size (128MB on x86). It can also be used to
1867 decrease the size and leave more room for directly
1868 mapped kernel RAM.
1869
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001870 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1871 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001873 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1874 Format: <command>
1875
1876 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1877 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07001878
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879 waveartist= [HW,OSS]
1880 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07001881
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 wd33c93= [HW,SCSI]
1883 See header of drivers/scsi/wd33c93.c.
1884
1885 wd7000= [HW,SCSI]
1886 See header of drivers/scsi/wd7000.c.
1887
1888 wdt= [WDT] Watchdog
1889 See Documentation/watchdog/watchdog.txt.
1890
1891 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1892 xd_geo= See header of drivers/block/xd.c.
1893
1894 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001895 Format:
1896 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001897
Andi Kleena62eaf12006-02-16 23:41:58 +01001898 norandmaps Don't use address space randomization
1899 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1900
Jan Beulich6d0185e2006-12-07 02:14:13 +01001901 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1902 This is useful to get more information why
1903 you got a "dwarf2 unwinder stuck"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904
Randy Dunlapa9913042005-10-23 12:57:11 -07001905______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906
1907TODO:
1908
1909 Add documentation for ALSA options.
1910 Add more DRM drivers.