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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
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.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100033 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020037 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080039 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070040 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070048 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070052 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070061 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070062 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070065 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070068 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070072 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070079 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070084 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090087 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070090 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -070099 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
103
104In addition, the following text indicates that the option:
105
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
109
110Parameters denoted with BOOT are actually interpreted by the boot
111loader, and have no meaning to the kernel directly.
112Do not modify the syntax of boot loader parameters without extreme
113need or coordination with <Documentation/i386/boot.txt>.
114
Karsten Weiss55588702007-02-13 13:26:21 +0100115There are also arch-specific kernel-parameters not documented here.
116See for example <Documentation/x86_64/boot-options.txt>.
117
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119a trailing = on the name of any parameter states that that parameter will
120be entered as an environment variable, whereas its absence indicates that
121it will appear as a kernel argument readable via /proc/cmdline by programs
122running once the system is up.
123
jens m. noedler9c4751f2006-09-29 02:00:27 -0700124The number of kernel parameters is not limited, but the length of the
125complete command line (parameters including spaces etc.) is limited to
126a fixed number of characters. This limit depends on the architecture
127and is between 256 and 4096 characters. It is defined in the file
128./include/asm/setup.h as COMMAND_LINE_SIZE.
129
130
Bernhard Walle03d926f2007-03-06 02:29:44 -0800131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700133 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700138 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 strictly ACPI specification compliant.
140
141 See also Documentation/pm.txt, pci=noacpi
142
Len Browna1fdcc02007-03-11 03:26:14 -0400143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400147 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400148
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode }
151 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700152
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700154 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
Randy Dunlapa9913042005-10-23 12:57:11 -0700156 acpi_irq_balance [HW,ACPI]
157 ACPI will balance active IRQs
158 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Randy Dunlapa9913042005-10-23 12:57:11 -0700160 acpi_irq_nobalance [HW,ACPI]
161 ACPI will not move active IRQs (default)
162 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163
Randy Dunlapa9913042005-10-23 12:57:11 -0700164 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 Format: <irq>,<irq>...
167
Randy Dunlapa9913042005-10-23 12:57:11 -0700168 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 Format: <irq>,<irq>...
170
Len Brown67effe82007-07-26 00:50:06 -0400171 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172
Len Browna1f9e652006-01-25 23:47:36 -0500173 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
174 Format: To spoof as Windows 98: ="Microsoft Windows"
175
Len Brownae00d812007-05-29 18:43:33 -0400176 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
177 acpi_osi="string1" # add string1 -- only one string
178 acpi_osi="!string2" # remove built-in string2
179 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
181 acpi_serialize [HW,ACPI] force serialization of AML methods
182
183 acpi_skip_timer_override [HW,ACPI]
184 Recognize and ignore IRQ0/pin2 Interrupt Override.
185 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100186 acpi_use_timer_override [HW,ACPI}
187 Use timer override. For some broken Nvidia NF5 boards
188 that require a timer override, but don't have
189 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
Zhang Ruif9891062007-04-24 13:53:22 +0800191 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700193 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 1: enable, 0: disable. It is useful for boot time
195 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800196 via /sys/module/acpi/parameters/debug_layer.
197 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
198 Available bits (add the numbers together) to enable debug output
199 for specific parts of the ACPI subsystem:
200 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
201 0x10 namespace 0x20 parser 0x40 dispatcher
202 0x80 executer 0x100 resources 0x200 acpica debugger
203 0x400 os services 0x800 acpica disassembler.
204 The number can be in decimal or prefixed with 0x in hex.
205 Warning: Many of these options can produce a lot of
206 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207
Zhang Ruif9891062007-04-24 13:53:22 +0800208 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700210 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 1: enable, 0: disable. It is useful for boot time
212 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800213 via /sys/module/acpi/parameters/debug_level.
214 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
215 Available bits (add the numbers together) to enable different
216 debug output levels of the ACPI subsystem:
217 0x01 error 0x02 warn 0x04 init 0x08 debug object
218 0x10 info 0x20 init names 0x40 parse 0x80 load
219 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
220 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
221 0x10000 resources 0x20000 user requests 0x40000 package.
222 The number can be in decimal or prefixed with 0x in hex.
223 Warning: Many of these options can produce a lot of
224 output and make your system unusable. Be very careful.
225
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700226 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
230
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000231 agp= [AGP]
232 { off | try_unsupported }
233 off: disable AGP support
234 try_unsupported: try to drive unsupported chipsets
235 (may crash computer or cause data corruption)
236
Chuck Ebbert66759a02005-09-12 18:49:25 +0200237 enable_timer_pin_1 [i386,x86-64]
238 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700239 Can be useful to work around chipset bugs
240 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200241 The kernel tries to set a reasonable default.
242
243 disable_timer_pin_1 [i386,x86-64]
244 Disable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs.
246
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 ad1848= [HW,OSS]
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
249
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 advansys= [HW,SCSI]
251 See header of drivers/scsi/advansys.c.
252
253 advwdt= [HW,WDT] Advantech WDT
254 Format: <iostart>,<iostop>
255
256 aedsp16= [HW,OSS] Audio Excel DSP 16
257 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
258 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700259
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 aha152x= [HW,SCSI]
261 See Documentation/scsi/aha152x.txt.
262
263 aha1542= [HW,SCSI]
264 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
265
266 aic7xxx= [HW,SCSI]
267 See Documentation/scsi/aic7xxx.txt.
268
269 aic79xx= [HW,SCSI]
270 See Documentation/scsi/aic79xx.txt.
271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 amijoy.map= [HW,JOY] Amiga joystick support
273 Map of devices attached to JOY0DAT and JOY1DAT
274 Format: <a>,<b>
275 See also Documentation/kernel/input/joystick.txt
276
277 analog.map= [HW,JOY] Analog joystick and gamepad support
278 Specifies type or capabilities of an analog joystick
279 connected to one of 16 gameports
280 Format: <type1>,<type2>,..<type16>
281
Randy Dunlapa9913042005-10-23 12:57:11 -0700282 apc= [HW,SPARC]
283 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 Format: noidle
285 Disable APC CPU standby support. SPARCstation-Fox does
286 not play well with APC CPU idle - disable it if you have
287 APC and your system crashes randomly.
288
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700289 apic= [APIC,i386] Advanced Programmable Interrupt Controller
290 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700294
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
297
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
299 Format: <io>,<irq>,<nodeID>
300
301 ataflop= [HW,M68k]
302
303 atarimouse= [HW,MOUSE] Atari Mouse
304
305 atascsi= [HW,SCSI] Atari SCSI
306
307 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
308 EzKey and similar keyboards
309
310 atkbd.reset= [HW] Reset keyboard during initialization
311
Randy Dunlapa9913042005-10-23 12:57:11 -0700312 atkbd.set= [HW] Select keyboard code set
313 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314
315 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
316 keyboards
317
318 atkbd.softraw= [HW] Choose between synthetic and real raw mode
319 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700320
321 atkbd.softrepeat= [HW]
322 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323
324 autotest [IA64]
325
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 baycom_epp= [HW,AX25]
327 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700328
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
330 Format: <io>,<mode>
331 See header of drivers/net/hamradio/baycom_par.c.
332
Randy Dunlapa9913042005-10-23 12:57:11 -0700333 baycom_ser_fdx= [HW,AX25]
334 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 Format: <io>,<irq>,<mode>[,<baud>]
336 See header of drivers/net/hamradio/baycom_ser_fdx.c.
337
Randy Dunlapa9913042005-10-23 12:57:11 -0700338 baycom_ser_hdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 Format: <io>,<irq>,<mode>
341 See header of drivers/net/hamradio/baycom_ser_hdx.c.
342
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700343 boot_delay= Milliseconds to delay each printk during boot.
344 Values larger than 10 seconds (10000) are changed to
345 no delay (0).
346 Format: integer
347
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700349 bttv.radio= Most important insmod options are available as
350 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
352 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
353
354 BusLogic= [HW,SCSI]
355 See drivers/scsi/BusLogic.c, comment before function
356 BusLogic_ParseDriverOptions().
357
358 c101= [NET] Moxa C101 synchronous serial card
359
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700360 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 Sometimes CPU hardware bugs make them report the cache
362 size incorrectly. The kernel will attempt work arounds
363 to fix known problems, but for some CPUs it is not
364 possible to determine what the correct size should be.
365 This option provides an override for these situations.
366
James Morris20510f22007-10-16 23:31:32 -0700367 capability.disable=
368 [SECURITY] Disable capabilities. This would normally
369 be used only if an alternative security model is to be
370 configured. Potentially dangerous and should only be
371 used if you are entirely sure of the consequences.
372
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100373 ccw_timeout_log [S390]
374 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375
376 checkreqprot [SELINUX] Set initial checkreqprot flag value.
377 Format: { "0" | "1" }
378 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700379 0 -- check protection applied by kernel (includes
380 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 1 -- check protection requested by application.
382 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700383 Value can be changed at runtime via
384 /selinux/checkreqprot.
385
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100386 cio_ignore= [S390]
387 See Documentation/s390/CommonIO for details.
388
389 cio_msg= [S390]
390 See Documentation/s390/CommonIO for details.
391
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700392 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700393 [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
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700399 clocksource= [GENERIC_TIME] Override the default clocksource
400 Format: <string>
401 Override the default clocksource and use the clocksource
402 with the name specified.
403 Some clocksource names to choose from, depending on
404 the platform:
405 [all] jiffies (this is the base, fallback clocksource)
406 [ACPI] acpi_pm
407 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
408 pxa_timer,timer3,32k_counter,timer0_1
409 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700410 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700411 scx200_hrt on Geode; cyclone on IBM x440
412 [MIPS] MIPS
413 [PARISC] cr16
414 [S390] tod
415 [SH] SuperH
416 [SPARC64] tick
417 [X86-64] hpet,tsc
418
Andi Kleenac72e782008-01-30 13:33:21 +0100419 clearcpuid=BITNUM [X86]
420 Disable CPUID feature X for the kernel. See
421 include/asm-x86/cpufeature.h for the valid bit numbers.
422 Note the Linux specific bits are not necessarily
423 stable over kernel options, but the vendor specific
424 ones should be.
425 Also note that user programs calling CPUID directly
426 or using the feature without checking anything
427 will still see it. This just prevents it from
428 being used by the kernel or shown in /proc/cpuinfo.
429 Also note the kernel might malfunction if you disable
430 some critical bits.
431
Arjan van de Vena25bd942008-01-30 13:33:08 +0100432 code_bytes [IA32/X86_64] How many bytes of object code to print
433 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100434 Range: 0 - 8192
435 Default: 64
436
Andi Kleenf9262c12006-03-08 17:57:25 -0800437 disable_8254_timer
438 enable_8254_timer
439 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
440 over the 8254 in addition to over the IO-APIC. The
441 kernel tries to set a sensible default.
442
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200443 hpet= [X86-32,HPET] option to control HPET usage
444 Format: { enable (default) | disable | force }
445 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100446 force: allow force enabled of undocumented chips (ICH4,
447 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700450 Format:
451 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
454 Format: <io>[,<irq>]
455
Randy Dunlapa9913042005-10-23 12:57:11 -0700456 com90xx= [HW,NET]
457 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 Format: <io>[,<irq>[,<memstart>]]
459
460 condev= [HW,S390] console device
461 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700462
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 console= [KNL] Output console device and options.
464
465 tty<n> Use the virtual console device <n>.
466
467 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800468 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800470 the form "bbbbpnf", where "bbbb" is the baud rate,
471 "p" is parity ("n", "o", or "e"), "n" is number of
472 bits, and "f" is flow control ("r" for RTS or
473 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800475 See Documentation/serial-console.txt for more
476 information. See
477 Documentation/networking/netconsole.txt for an
478 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700480 uart[8250],io,<addr>[,options]
481 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 Start an early, polled-mode console on the 8250/16550
483 UART at the specified I/O port or MMIO address,
484 switching to the matching ttyS device later. The
485 options are the same as for ttyS, above.
486
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700487 earlycon= [KNL] Output early console device and options.
488 uart[8250],io,<addr>[,options]
489 uart[8250],mmio,<addr>[,options]
490 Start an early, polled-mode console on the 8250/16550
491 UART at the specified I/O port or MMIO address.
492 The options are the same as for ttyS, above.
493
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700494 no_console_suspend
495 [HW] Never suspend the console
496 Disable suspending of consoles during suspend and
497 hibernate operations. Once disabled, debugging
498 messages can reach various consoles while the rest
499 of the system is being put to sleep (ie, while
500 debugging driver suspend/resume hooks). This may
501 not work reliably with all consoles, but is known
502 to work with serial and VGA consoles.
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700505 Format:
506 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700508 crashkernel=nn[KMG]@ss[KMG]
509 [KNL] Reserve a chunk of physical memory to
510 hold a kernel to switch to with kexec on panic.
511
Bernhard Wallefb391592007-10-18 23:41:02 -0700512 crashkernel=range1:size1[,range2:size2,...][@offset]
513 [KNL] Same as above, but depends on the memory
514 in the running system. The syntax of range is
515 start-[end] where start and end are both
516 a memory unit (amount[KMG]). See also
517 Documentation/kdump/kdump.txt for a example.
518
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 cs4232= [HW,OSS]
520 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
521
522 cs89x0_dma= [HW,NET]
523 Format: <dma>
524
525 cs89x0_media= [HW,NET]
526 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700527
Randy Dunlapa9913042005-10-23 12:57:11 -0700528 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 See header of drivers/s390/block/dasd_devmap.c.
530
531 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
532 (one device per port)
533 Format: <port#>,<type>
534 See also Documentation/input/joystick-parport.txt
535
536 debug [KNL] Enable kernel debugging (events log level).
537
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700538 debug_locks_verbose=
539 [KNL] verbose self-tests
540 Format=<0|1>
541 Print debugging info while doing the locking API
542 self-tests.
543 We default to 0 (no extra messages), setting it to
544 1 will print _a lot_ more information - normally
545 only useful to kernel developers.
546
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 decnet= [HW,NET]
548 Format: <area>[,<node>]
549 See also Documentation/networking/decnet.txt.
550
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000551 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700552 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
553 Change the default blue palette of the console.
554 This is a 16-member array composed of values
555 ranging from 0-255.
556
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000557 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700558 Format: <green0>,<green1>,<green2>,...,<green15>
559 Change the default green palette of the console.
560 This is a 16-member array composed of values
561 ranging from 0-255.
562
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000563 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700564 Format: <red0>,<red1>,<red2>,...,<red15>
565 Change the default red palette of the console.
566 This is a 16-member array composed of values
567 ranging from 0-255.
568
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000569 vt.default_utf8=
570 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700571 Format=<0|1>
572 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000573 Default is 1, i.e. UTF-8 mode is enabled for all
574 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700575
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 dhash_entries= [KNL]
577 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700578
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 digi= [HW,SERIAL]
580 IO parameters + enable/disable command.
581
582 digiepca= [HW,SERIAL]
583 See drivers/char/README.epca and
584 Documentation/digiepca.txt.
585
Yinghai Lu093af8d2008-01-30 13:33:32 +0100586 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100587 By default the kernel will trim any uncacheable
588 memory out of your available memory pool based on
589 MTRR settings. This parameter disables that behavior,
590 possibly causing your machine to run very slowly.
591
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 dmasound= [HW,OSS] Sound subsystem buffers
593
594 dscc4.setup= [NET]
595
596 dtc3181e= [HW,SCSI]
597
Robin Getz0ae53642007-10-09 17:24:49 +0800598 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 earlyprintk=vga
600 earlyprintk=serial[,ttySn[,baudrate]]
601
Randy Dunlapa9913042005-10-23 12:57:11 -0700602 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 takes over.
604
605 Only vga or serial at a time, not both.
606
607 Currently only ttyS0 and ttyS1 are supported.
608
609 Interaction with the standard serial driver is not
610 very good.
611
612 The VGA output is eventually overwritten by the real
613 console.
614
615 eata= [HW,SCSI]
616
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 edd= [EDD]
618 Format: {"of[f]" | "sk[ipmbr]"}
619 See comment in arch/i386/boot/edd.S
620
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 eisa_irq_edge= [PARISC,HW]
622 See header of drivers/parisc/eisa.c.
623
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700624 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 See comment before function elanfreq_setup() in
626 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
627
628 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800629 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700630 See Documentation/block/as-iosched.txt and
631 Documentation/block/deadline-iosched.txt for details.
632
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700633 elfcorehdr= [X86-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700634 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800635 image elf header. Generally kexec loader will
636 pass this option to capture kernel.
637 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638
639 enforcing [SELINUX] Set initial enforcing status.
640 Format: {"0" | "1"}
641 See security/selinux/Kconfig help text.
642 0 -- permissive (log only, no denials).
643 1 -- enforcing (deny and log).
644 Default value is 0.
645 Value can be changed at runtime via /selinux/enforce.
646
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 es1371= [HW,OSS]
648 Format: <spdif>,[<nomix>,[<amplifier>]]
649 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700650
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 ether= [HW,NET] Ethernet cards parameters
652 This option is obsoleted by the "netdev=" option, which
653 has equivalent usage. See its documentation for details.
654
655 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
656 Format: <io>[,<irq>]
657
Akinobu Mitade1ba092006-12-08 02:39:42 -0800658 failslab=
659 fail_page_alloc=
660 fail_make_request=[KNL]
661 General fault injection mechanism.
662 Format: <interval>,<probability>,<space>,<times>
663 See also /Documentation/fault-injection/.
664
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 fd_mcs= [HW,SCSI]
666 See header of drivers/scsi/fd_mcs.c.
667
668 fdomain= [HW,SCSI]
669 See header of drivers/scsi/fdomain.c.
670
671 floppy= [HW]
672 See Documentation/floppy.txt.
673
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 gamecon.map[2|3]=
675 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
676 support via parallel port (up to 5 devices per port)
677 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
678 See also Documentation/input/joystick-parport.txt
679
680 gamma= [HW,DRM]
681
Yinghai Luaaf23042008-01-30 13:33:09 +0100682 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
683 Format: off | on
684 default: on
685
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 gdth= [HW,SCSI]
687 See header of drivers/scsi/gdth.c.
688
689 gpt [EFI] Forces disk with valid GPT signature but
690 invalid Protective MBR to be treated as GPT.
691
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 gvp11= [HW,SCSI]
693
694 hashdist= [KNL,NUMA] Large hashes allocated during boot
695 are distributed across NUMA nodes. Defaults on
696 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700697 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
699 hcl= [IA-64] SGI's Hardware Graph compatibility layer
700
701 hd= [EIDE] (E)IDE hard drive subsystem geometry
702 Format: <cyl>,<head>,<sect>
703
704 hd?= [HW] (E)IDE subsystem
705 hd?lun= See Documentation/ide.txt.
706
707 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
708 size of <nn>. This works even on boxes that have no
709 highmem otherwise. This also works to reduce highmem
710 size on bigger boxes.
711
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800712 highres= [KNL] Enable/disable high resolution timer mode.
713 Valid parameters: "on", "off"
714 Default: "on"
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 hisax= [HW,ISDN]
717 See Documentation/isdn/README.HiSax.
718
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700719 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
Jon Tollefson4ec161c2008-01-04 09:59:50 +1100720 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200723 i8042.dumbkbd [HW] Pretend that controller can only read data from
724 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 (Don't attempt to blink the leds)
726 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500727 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 i8042.nomux [HW] Don't check presence of an active multiplexing
729 controller
730 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
731 controllers
732 i8042.panicblink=
733 [HW] Frequency with which keyboard LEDs should blink
734 when kernel panics (default is 0.5 sec)
735 i8042.reset [HW] Reset the controller during init and cleanup
736 i8042.unlock [HW] Unlock (ignore) the keylock
737
738 i810= [HW,DRM]
739
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700740 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
741 indicates that the driver is running on unsupported
742 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
744 does not match list of supported models.
745 i8k.power_status
746 [HW] Report power status in /proc/i8k
747 (disabled by default)
748 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
749 capability is set.
750
751 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
752 See Documentation/mca.txt.
753
754 icn= [HW,ISDN]
755 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
756
757 ide= [HW] (E)IDE subsystem
758 Format: ide=nodma or ide=doubler or ide=reverse
759 See Documentation/ide.txt.
760
761 ide?= [HW] (E)IDE subsystem
762 Format: ide?=noprobe or chipset specific parameters.
763 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700764
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
766 See Documentation/ide.txt.
767
Andi Kleenf039b752007-05-02 19:27:12 +0200768 idle= [X86]
769 Format: idle=poll or idle=mwait
770 Poll forces a polling idle loop that can slightly improves the performance
771 of waking up a idle CPU, but will use a lot of power and make the system
772 run hot. Not recommended.
773 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
774 to not use it because it doesn't save as much power as a normal idle
775 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
776 as idle=poll.
Randy Dunlapa9913042005-10-23 12:57:11 -0700777
Ingo Molnar792908222006-12-06 20:40:51 -0800778 ignore_loglevel [KNL]
779 Ignore loglevel setting - this will print /all/
780 kernel messages to the console. Useful for debugging.
781
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 ihash_entries= [KNL]
783 Set number of hash buckets for inode cache.
784
785 in2000= [HW,SCSI]
786 See header of drivers/scsi/in2000.c.
787
788 init= [KNL]
789 Format: <full_path>
790 Run specified binary instead of /sbin/init as init
791 process.
792
793 initcall_debug [KNL] Trace initcalls as they are executed. Useful
794 for working out where the kernel is dying during
795 startup.
796
797 initrd= [BOOT] Specify the location of the initial ramdisk
798
799 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
800 Format: <irq>
801
802 inttest= [IA64]
803
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700804 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
805 off
806 Disable intel iommu driver.
807 igfx_off [Default Off]
808 By default, gfx is mapped as normal device. If a gfx
809 device has a dedicated DMAR unit, the DMAR unit is
810 bypassed by not enabling DMAR with this option. In
811 this case, gfx device will use physical address for
812 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700813 forcedac [x86_64]
814 With this option iommu will not optimize to look
815 for io virtual address below 32 bit forcing dual
816 address cycle on pci bus for cards supporting greater
817 than 32 bit addressing. The default is to look
818 for translation below 32 bit and if not available
819 then look in the higher range.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700820
Rene Hermanb02aae92008-01-30 13:30:05 +0100821 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100822 0x80
823 Standard port 0x80 based delay
824 0xed
825 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100826 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100827 Simple two microseconds delay
828 none
829 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100830
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 io7= [HW] IO7 for Marvel based alpha systems
832 See comment before marvel_specify_io7 in
833 arch/alpha/kernel/core_marvel.c.
834
835 ip= [IP_PNP]
836 See Documentation/nfsroot.txt.
837
838 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700839 See comment before ip2_setup() in
840 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
842 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
843 See header of drivers/scsi/ips.c.
844
Simon Horman72c4a132006-09-13 19:57:18 -0700845 ports= [IP_VS_FTP] IPVS ftp helper module
846 Default is 21.
847 Up to 8 (IP_VS_APP_MAX_PORTS) ports
848 may be specified.
849 Format: <port>,<port>....
850
Alan Cox200803d2005-06-28 20:45:18 -0700851 irqfixup [HW]
852 When an interrupt is not handled search all handlers
853 for it. Intended to get systems with badly broken
854 firmware running.
855
856 irqpoll [HW]
857 When an interrupt is not handled search all handlers
858 for it. Also check all handlers each timer
859 interrupt. Intended to get systems with badly broken
860 firmware running.
861
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700863 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864
865 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800866 Format:
867 <cpu number>,...,<cpu number>
868 or
869 <cpu number>-<cpu number> (must be a positive range in ascending order)
870 or a mixture
871 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 This option can be used to specify one or more CPUs
873 to isolate from the general SMP balancing and scheduling
874 algorithms. The only way to move a process onto or off
875 an "isolated" CPU is via the CPU affinity syscalls.
876 <cpu number> begins at 0 and the maximum value is
877 "number of CPUs in system - 1".
878
879 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700880 alternative -- manually setting the CPU mask of all
881 tasks in the system -- can cause problems and
882 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883
Randy Dunlapa9913042005-10-23 12:57:11 -0700884 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
886 js= [HW,JOY] Analog joystick
887 See Documentation/input/joystick.txt.
888
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700889 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -0700890 specifies the amount of memory usable by the kernel
891 for non-movable allocations. The requested amount is
892 spread evenly throughout all nodes in the system. The
893 remaining memory in each node is used for Movable
894 pages. In the event, a node is too small to have both
895 kernelcore and Movable pages, kernelcore pages will
896 take priority and other nodes will have a larger number
897 of kernelcore pages. The Movable zone is used for the
898 allocation of pages that may be reclaimed or moved
899 by the page migration subsystem. This means that
900 HugeTLB pages may not be allocated from this zone.
901 Note that allocations like PTEs-from-HighMem still
902 use the HighMem zone if it exists, and the Normal
903 zone if it does not.
904
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700905 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -0700906 is similar to kernelcore except it specifies the
907 amount of memory used for migratable allocations.
908 If both kernelcore and movablecore is specified,
909 then kernelcore will be at *least* the specified
910 value but may be more. If movablecore on its own
911 is specified, the administrator must be careful
912 that the amount of memory usable for all allocations
913 is not too small.
914
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 keepinitrd [HW,ARM]
916
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700917 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 in oops dumps.
919
920 l2cr= [PPC]
921
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700922 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -0700923 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700925 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +0100926 C2 power state.
927
FD Camifcb71f62008-01-06 19:08:56 +0100928 libata.dma= [LIBATA] DMA control
929 libata.dma=0 Disable all PATA and SATA DMA
930 libata.dma=1 PATA and SATA Disk DMA only
931 libata.dma=2 ATAPI (CDROM) DMA only
932 libata.dma=4 Compact Flash DMA only
933 Combinations also work, so libata.dma=3 enables DMA
934 for disks and CDROMs, but not CFs.
935
Dave Jones78e70c22007-09-27 11:50:13 -0400936 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
937 when set.
938 Format: <int>
939
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 load_ramdisk= [RAM] List of ramdisks to load from floppy
941 See Documentation/ramdisk.txt.
942
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800943 lockd.nlm_grace_period=P [NFS] Assign grace period.
944 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800946 lockd.nlm_tcpport=N [NFS] Assign TCP port.
947 Format: <integer>
948
949 lockd.nlm_timeout=T [NFS] Assign timeout value.
950 Format: <integer>
951
952 lockd.nlm_udpport=M [NFS] Assign UDP port.
953 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954
955 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
956 Format: <irq>
957
958 loglevel= All Kernel Messages with a loglevel smaller than the
959 console loglevel will be printed to the console. It can
960 also be changed with klogd or other programs. The
961 loglevels are defined as follows:
962
963 0 (KERN_EMERG) system is unusable
964 1 (KERN_ALERT) action must be taken immediately
965 2 (KERN_CRIT) critical conditions
966 3 (KERN_ERR) error conditions
967 4 (KERN_WARNING) warning conditions
968 5 (KERN_NOTICE) normal but significant condition
969 6 (KERN_INFO) informational
970 7 (KERN_DEBUG) debug-level messages
971
972 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700973 Format: { n | nk | nM }
974 n must be a power of two. The default size
975 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976
Randy Dunlapaccaa242007-10-16 01:29:37 -0700977 logo.nologo [FB] Disables display of the built-in Linux logo.
978 This may be used to provide more screen space for
979 kernel log messages and is useful when debugging
980 kernel boot problems.
981
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 lp=0 [LP] Specify parallel ports to use, e.g,
983 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
984 lp=reset first parallel port). 'lp=0' disables the
985 lp=auto printer driver. 'lp=reset' (which can be
986 specified in addition to the ports) causes
987 attached printers to be reset. Using
988 lp=port1,port2,... specifies the parallel ports
989 to associate lp devices with, starting with
990 lp0. A port specification may be 'none' to skip
991 that lp device, or a parport name such as
992 'parport0'. Specifying 'lp=auto' instead of a
993 port specification list means that device IDs
994 from each port should be examined, to see if
995 an IEEE 1284-compliant printer is attached; if
996 so, the driver will manage that printer.
997 See also header of drivers/char/lp.c.
998
999 lpj=n [KNL]
1000 Sets loops_per_jiffy to given constant, thus avoiding
1001 time-consuming boot-time autodetection (up to 250 ms per
1002 CPU). 0 enables autodetection (default). To determine
1003 the correct value for your kernel, boot with normal
1004 autodetection and see what value is printed. Note that
1005 on SMP systems the preset will be applied to all CPUs,
1006 which is likely to cause problems if your CPUs need
1007 significantly divergent settings. An incorrect value
1008 will cause delays in the kernel to be wrong, leading to
1009 unpredictable I/O errors and other breakage. Although
1010 unlikely, in the extreme case this might damage your
1011 hardware.
1012
1013 ltpc= [NET]
1014 Format: <io>,<irq>,<dma>
1015
Randy Dunlapa9913042005-10-23 12:57:11 -07001016 mac5380= [HW,SCSI] Format:
1017 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018
Randy Dunlapa9913042005-10-23 12:57:11 -07001019 mac53c9x= [HW,SCSI] Format:
1020 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021
Randy Dunlapa9913042005-10-23 12:57:11 -07001022 machvec= [IA64] Force the use of a particular machine-vector
1023 (machvec) in a generic kernel.
1024 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025
Randy Dunlapa9913042005-10-23 12:57:11 -07001026 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 be mounted
1028 Format: <1-256>
1029
1030 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001031 should make use of. maxcpus=n : n >= 0 limits the
1032 kernel to using 'n' processors. n=0 is a special case,
1033 it is equivalent to "nosmp", which also disables
1034 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035
Bob Picco2b2c3752005-06-29 18:00:00 -07001036 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1037 equal to this physical address is ignored.
1038
Randy Dunlapa9913042005-10-23 12:57:11 -07001039 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 Should be between 1 and 2^32-1.
1041
1042 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001043 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 Should be between 1 and 16384.
1045
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001046 mca-pentium [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047
1048 mcatest= [IA-64]
1049
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001050 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051
Andi Kleen909dd322007-10-17 18:04:38 +02001052 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1053
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 md= [HW] RAID subsystems devices and level
1055 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001056
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 mdacon= [MDA]
1058 Format: <first>,<last>
1059 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001060
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1062 Amount of memory to be used when the kernel is not able
1063 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001064 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 address space collisions. Without memmap= PCI devices
1066 could be placed at addresses belonging to unused RAM.
1067
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001068 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 memory.
1070
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001071 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 E820 memory map, as specified by the user.
1073 Such memmap=exactmap lines can be constructed based on
1074 BIOS output or other requirements. See the memmap=nn@ss
1075 option description.
1076
1077 memmap=nn[KMG]@ss[KMG]
1078 [KNL] Force usage of a specific region of memory
1079 Region of memory to be used, from ss to ss+nn.
1080
1081 memmap=nn[KMG]#ss[KMG]
1082 [KNL,ACPI] Mark specific memory as ACPI data.
1083 Region of memory to be used, from ss to ss+nn.
1084
1085 memmap=nn[KMG]$ss[KMG]
1086 [KNL,ACPI] Mark specific memory as reserved.
1087 Region of memory to be used, from ss to ss+nn.
1088
1089 meye.*= [HW] Set MotionEye Camera parameters
1090 See Documentation/video4linux/meye.txt.
1091
Andres Salomon8f368812007-10-12 23:04:06 +02001092 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1093 Multi-Function General Purpose Timers on AMD Geode
1094 platforms.
1095
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001096 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1097 the BIOS has incorrectly applied a workaround. TinyBIOS
1098 version 0.98 is known to be affected, 0.99 fixes the
1099 problem by letting the user disable the workaround.
1100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 mga= [HW,DRM]
1102
1103 mousedev.tap_time=
1104 [MOUSE] Maximum time between finger touching and
1105 leaving touchpad surface for touch to be considered
1106 a tap and be reported as a left button click (for
1107 touchpads working in absolute mode only).
1108 Format: <msecs>
1109 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1110 reporting absolute coordinates, such as tablets
1111 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1112 reporting absolute coordinates, such as tablets
1113
1114 mpu401= [HW,OSS]
1115 Format: <io>,<irq>
1116
1117 MTD_Partition= [MTD]
1118 Format: <name>,<region-number>,<size>,<offset>
1119
Randy Dunlapa9913042005-10-23 12:57:11 -07001120 MTD_Region= [MTD] Format:
1121 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122
1123 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001124 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125
1126 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001127 [HW] Make the MicroTouch USB driver use raw coordinates
1128 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129
1130 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1131
1132 NCR_D700= [HW,SCSI]
1133 See header of drivers/scsi/NCR_D700.c.
1134
1135 ncr5380= [HW,SCSI]
1136
1137 ncr53c400= [HW,SCSI]
1138
1139 ncr53c400a= [HW,SCSI]
1140
1141 ncr53c406a= [HW,SCSI]
1142
1143 ncr53c8xx= [HW,SCSI]
1144
1145 netdev= [NET] Network devices parameters
1146 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1147 Note that mem_start is often overloaded to mean
1148 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001149 This usage is only documented in each driver source
1150 file if at all.
1151
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 nfsaddrs= [NFS]
1153 See Documentation/nfsroot.txt.
1154
1155 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1156 See Documentation/nfsroot.txt.
1157
Trond Myklebusta72b4422006-01-03 09:55:41 +01001158 nfs.callback_tcpport=
1159 [NFS] set the TCP port on which the NFSv4 callback
1160 channel should listen.
1161
Trond Myklebust58df0952006-01-03 09:55:57 +01001162 nfs.idmap_cache_timeout=
1163 [NFS] set the maximum lifetime for idmapper cache
1164 entries.
1165
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001166 nfs.enable_ino64=
1167 [NFS] enable 64-bit inode numbers.
1168 If zero, the NFS client will fake up a 32-bit inode
1169 number for the readdir() and stat() syscalls instead
1170 of returning the full 64-bit number.
1171 The default is to return 64-bit inode numbers.
1172
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001173 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1174 when a NMI is triggered.
1175 Format: [state][,regs][,debounce][,die]
1176
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001177 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001179 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 emulation library even if a 387 maths coprocessor
1181 is present.
1182
Christoph Lameterc1aee212007-05-31 00:40:47 -07001183 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1184 caches in the slab allocator. Saves per-node memory,
1185 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001186
Randy Dunlapa9913042005-10-23 12:57:11 -07001187 noalign [KNL,ARM]
1188
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 noapic [SMP,APIC] Tells the kernel to not make use of any
1190 IOAPICs that may be present in the system.
1191
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 nobats [PPC] Do not use BATs for mapping kernel lowmem
1193 on "Classic" PPC cores.
1194
1195 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001196
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001197 nodelayacct [KNL] Disable per-task delay accounting
1198
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1200
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001201 noefi [X86-32,X86-64] Disable EFI runtime services support.
1202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203 noexec [IA-64]
1204
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001205 noexec [X86-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 noexec=on: enable non-executable mappings (default)
1207 noexec=off: disable nn-executable mappings
1208
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001209 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001210 register save and restore. The kernel will only save
1211 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212
Andi Kleen191679f2008-01-30 13:33:21 +01001213 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1214
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001216
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001217 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 instruction doesn't work correctly and not to
1219 use it.
1220
1221 nohalt [IA-64] Tells the kernel not to use the power saving
1222 function PAL_HALT_LIGHT when idle. This increases
1223 power-consumption. On the positive side, it reduces
1224 interrupt wake-up latency, which may improve performance
1225 in certain environments such as networked servers or
1226 real-time systems.
1227
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001228 nohz= [KNL] Boottime enable/disable dynamic ticks
1229 Valid arguments: on, off
1230 Default: on
1231
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001232 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
Zachary Amsden8542b202006-12-07 02:14:09 +01001233
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001234 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 disable unhandled interrupt sources.
1236
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001237 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001238 broken timer IRQ sources.
1239
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240 noisapnp [ISAPNP] Disables ISA PnP code.
1241
1242 noinitrd [RAM] Tells the kernel not to load any configured
1243 initial RAM disk.
1244
1245 nointroute [IA-64]
1246
Tony Luck0aa366f2007-07-20 11:22:30 -07001247 nojitter [IA64] Disables jitter checking for ITC timers.
1248
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001249 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001251 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001252
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 noltlbs [PPC] Do not use large page/tlb entries for kernel
1254 lowmem mapping on PPC40x.
1255
Horms312f1f02006-02-22 09:57:55 +09001256 nomca [IA-64] Disable machine check abort handling
1257
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001258 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001259
Andres Salomon83d73842007-10-12 23:04:06 +02001260 nomfgpt [X86-32] Disable Multi-Function General Purpose
1261 Timer usage (for AMD Geode machines).
1262
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001263 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001264
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001265 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001266 with UP alternatives
1267
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268 noresidual [PPC] Don't use residual data on PReP machines.
1269
Randy Dunlapa9913042005-10-23 12:57:11 -07001270 noresume [SWSUSP] Disables resume and restores original swap
1271 space.
1272
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 no-scroll [VGA] Disables scrollback.
1274 This is required for the Braillex ib80-piezo Braille
1275 reader made by F.H. Papenmeier (Germany).
1276
1277 nosbagart [IA-64]
1278
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001279 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001280
Len Brown61ec7562007-08-16 03:34:22 -04001281 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1282 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283
Dave Jones97842212007-07-15 23:41:05 -07001284 nosoftlockup [KNL] Disable the soft-lockup detector.
1285
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 nosync [HW,M68K] Disables sync negotiation for all devices.
1287
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001288 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
1290 nousb [USB] Disable the USB subsystem
1291
1292 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001293
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001294 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1295 one of ['zone', 'node', 'default'] can be specified
1296 This can be set from sysctl after boot.
1297 See Documentation/sysctl/vm.txt for details.
1298
Dave Jonesa61c2d72006-01-07 23:18:19 +00001299 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1300
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 opl3= [HW,OSS]
1302 Format: <io>
1303
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 oprofile.timer= [HW]
1305 Use timer interrupt instead of performance counters
1306
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 osst= [HW,SCSI] SCSI Tape Driver
1308 Format: <buffer_size>,<write_threshold>
1309 See also Documentation/scsi/st.txt.
1310
1311 panic= [KNL] Kernel behaviour on panic
1312 Format: <timeout>
1313
1314 parkbd.port= [HW] Parallel port number the keyboard adapter is
1315 connected to, default is 0.
1316 Format: <parport#>
1317 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1318 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001319 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320
Randy Dunlapa9913042005-10-23 12:57:11 -07001321 parport= [HW,PPT] Specify parallel ports. 0 disables.
1322 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1323 Use 'auto' to force the driver to use any
1324 IRQ/DMA settings detected (the default is to
1325 ignore detected IRQ/DMA settings because of
1326 possible conflicts). You can specify the base
1327 address, IRQ, and DMA settings; IRQ and DMA
1328 should be numbers, or 'auto' (for using detected
1329 settings on that particular port), or 'nofifo'
1330 (to avoid using a FIFO even if it is detected).
1331 Parallel ports are assigned in the order they
1332 are specified on the command line, starting
1333 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
Randy Dunlapa9913042005-10-23 12:57:11 -07001335 parport_init_mode= [HW,PPT]
1336 Configure VIA parallel port to operate in
1337 a specific mode. This is necessary on Pegasos
1338 computer where firmware has no options for setting
1339 up parallel port mode and sets it to spp.
1340 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 Format: [spp|ps2|epp|ecp|ecpepp]
1342
Randy Dunlapa9913042005-10-23 12:57:11 -07001343 pas2= [HW,OSS] Format:
1344 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1345
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 pas16= [HW,SCSI]
1347 See header of drivers/scsi/pas16.c.
1348
Andrew Mortondd287792006-03-23 03:00:57 -08001349 pause_on_oops=
1350 Halt all CPUs after the first oops has been printed for
1351 the specified number of seconds. This is to be used if
1352 your oopses keep scrolling off the screen.
1353
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 pcbit= [HW,ISDN]
1355
1356 pcd. [PARIDE]
1357 See header of drivers/block/paride/pcd.c.
1358 See also Documentation/paride.txt.
1359
Randy Dunlapa9913042005-10-23 12:57:11 -07001360 pci=option[,option...] [PCI] various PCI subsystem options:
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001361 off [X86-32] don't probe for the PCI bus
1362 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001363 the hardware directly. Use this if your machine
1364 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001365 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001366 hardware access methods are allowed. Use this
1367 if you experience crashes upon bootup and you
1368 suspect they are caused by the BIOS.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001369 conf1 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001370 Mechanism 1.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001371 conf2 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001372 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001373 noaer [PCIE] If the PCIEAER kernel config parameter is
1374 enabled, this kernel boot option can be used to
1375 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001376 nodomains [PCI] Disable support for multiple PCI
1377 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001378 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001379 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001380 nomsi [MSI] If the PCI_MSI kernel config parameter is
1381 enabled, this kernel boot option can be used to
1382 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001383 nosort [X86-32] Don't sort PCI devices according to
Randy Dunlapa9913042005-10-23 12:57:11 -07001384 order given by the PCI BIOS. This sorting is
1385 done to get a device order compatible with
1386 older kernels.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001387 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001388 routing table. These calls are known to be buggy
1389 on several machines and they hang the machine
1390 when used, but on other computers it's the only
1391 way to get the interrupt routing table. Try
1392 this option if the kernel is unable to allocate
1393 IRQs or discover secondary PCI buses on your
1394 motherboard.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001395 rom [X86-32] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001396 Use with caution as certain devices share
1397 address decoders between ROMs and other
1398 resources.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001399 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001400 assigned automatically to PCI devices. You can
1401 make the kernel exclude IRQs of your ISA cards
1402 this way.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001403 pirqaddr=0xAAAAA [X86-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001404 of the PIRQ table (normally generated
1405 by the BIOS) if it is outside the
1406 F0000h-100000h range.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001407 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001408 useful if the kernel is unable to find your
1409 secondary buses and you want to tell it
1410 explicitly which ones they are.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001411 assign-busses [X86-32] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001412 numbers ourselves, overriding
1413 whatever the firmware may have done.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001414 usepirqmask [X86-32] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001415 in the BIOS $PIR table. This is needed on
1416 some systems with broken BIOSes, notably
1417 some HP Pavilion N5400 and Omnibook XE3
1418 notebooks. This will have no effect if ACPI
1419 IRQ routing is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001420 noacpi [X86-32] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001421 or for PCI scanning.
Gary Hade62f420f2007-10-03 15:56:51 -07001422 use_crs [X86-32] Use _CRS for PCI resource
1423 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001424 routeirq Do IRQ routing for all PCI devices.
1425 This is normally done in pci_enable_device(),
1426 so this option is a temporary workaround
1427 for broken drivers that don't call it.
1428 firmware [ARM] Do not re-enumerate the bus but instead
1429 just use the configuration from the
1430 bootloader. This is currently used on
1431 IXP2000 systems where the bus has to be
1432 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001433 noearly [X86] Don't do any early type 1 scanning.
1434 This might help on some broken boards which
1435 machine check when some devices' config space
1436 is read. But various workarounds are disabled
1437 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001438 bfsort Sort PCI devices into breadth-first order.
1439 This sorting is done to get a device
1440 order compatible with older (<= 2.4) kernels.
1441 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001442 cbiosize=nn[KMG] The fixed amount of bus space which is
1443 reserved for the CardBus bridge's IO window.
1444 The default value is 256 bytes.
1445 cbmemsize=nn[KMG] The fixed amount of bus space which is
1446 reserved for the CardBus bridge's memory
1447 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001448
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 pcmv= [HW,PCMCIA] BadgePAD 4
1450
1451 pd. [PARIDE]
1452 See Documentation/paride.txt.
1453
1454 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1455 boot time.
1456 Format: { 0 | 1 }
1457 See arch/parisc/kernel/pdc_chassis.c
1458
1459 pf. [PARIDE]
1460 See Documentation/paride.txt.
1461
1462 pg. [PARIDE]
1463 See Documentation/paride.txt.
1464
1465 pirq= [SMP,APIC] Manual mp-table setup
1466 See Documentation/i386/IO-APIC.txt.
1467
1468 plip= [PPT,NET] Parallel port network link
1469 Format: { parport<nr> | timid | 0 }
1470 See also Documentation/parport.txt.
1471
1472 pnpacpi= [ACPI]
1473 { off }
1474
1475 pnpbios= [ISAPNP]
1476 { on | off | curr | res | no-curr | no-res }
1477
1478 pnp_reserve_irq=
1479 [ISAPNP] Exclude IRQs for the autoconfiguration
1480
1481 pnp_reserve_dma=
1482 [ISAPNP] Exclude DMAs for the autoconfiguration
1483
1484 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001485 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486
1487 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001488 [ISAPNP] Exclude memory regions for the
1489 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 Ranges are in pairs (memory base and size).
1491
Ingo Molnar45807a12007-07-15 23:40:10 -07001492 print-fatal-signals=
1493 [KNL] debug: print fatal signals
1494 print-fatal-signals=1: print segfault info to
1495 the kernel console.
1496 default: off.
1497
Randy Dunlape84845c2007-07-15 23:40:25 -07001498 printk.time= Show timing data prefixed to each printk message line
1499 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1500
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001502 Format: [schedule,]<number>
1503 Param: "schedule" - profile schedule points.
1504 Param: <number> - step/bucket size as a power of 2 for
1505 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001506 Param: "sleep" - profile D-state sleeping (millisecs).
1507 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001508 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509
Randy Dunlapa9913042005-10-23 12:57:11 -07001510 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 Limit processor to maximum C-state
1512 max_cstate=9 overrides any DMI blacklist limit.
1513
Len Brown41c0d862005-12-28 12:43:51 -05001514 processor.nocst [HW,ACPI]
1515 Ignore the _CST method to determine C-states,
1516 instead using the legacy FADT method
1517
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1519 before loading.
1520 See Documentation/ramdisk.txt.
1521
Randy Dunlapa9913042005-10-23 12:57:11 -07001522 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1523 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1525 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001526 psmouse.resetafter= [HW,MOUSE]
1527 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528 (0 = never).
1529 psmouse.resolution=
1530 [HW,MOUSE] Set desired mouse resolution, in dpi.
1531 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001532 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 0 = disabled, 1 = enabled (default).
1534
1535 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001536 Format:
1537 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538
1539 pt. [PARIDE]
1540 See Documentation/paride.txt.
1541
Kay Sieversdc8c8582007-08-15 12:25:38 +02001542 pty.legacy_count=
1543 [KNL] Number of legacy pty's. Overwrites compiled-in
1544 default number.
1545
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001546 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 r128= [HW,DRM]
1549
1550 raid= [HW,RAID]
1551 See Documentation/md.txt.
1552
Randy Dunlapa9913042005-10-23 12:57:11 -07001553 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 See Documentation/ramdisk.txt.
1558
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001559 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1560 RCU callbacks to process in one batch.
1561
1562 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1563 RCU callbacks over which batch limiting is disabled.
1564
1565 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1566 RCU callbacks below which batch limiting is re-enabled.
1567
Olof Johanssonffdfc402005-09-06 15:17:19 -07001568 rdinit= [KNL]
1569 Format: <full_path>
1570 Run specified binary instead of /init from the ramdisk,
1571 used for early userspace startup. See initrd.
1572
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001573 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001575 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576
1577 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1578
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001579 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001580 Format: nn[KMG]
1581 Reserves a hole at the top of the kernel virtual
1582 address space.
1583
Vivek Goyal7e962872006-09-27 01:50:44 -07001584 reset_devices [KNL] Force drivers to reset the underlying device
1585 during initialization.
1586
Randy Dunlapa9913042005-10-23 12:57:11 -07001587 resume= [SWSUSP]
1588 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001590 resume_offset= [SWSUSP]
1591 Specify the offset from the beginning of the partition
1592 given by "resume=" at which the swap header is located,
1593 in <PAGE_SIZE> units (needed only for swap files).
1594 See Documentation/power/swsusp-and-swap-files.txt
1595
Michael Neuling0a7b35c2007-02-10 01:44:33 -08001596 retain_initrd [RAM] Keep initrd memory after extraction
1597
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598 rhash_entries= [KNL,NET]
1599 Set number of hash buckets for route cache
1600
1601 riscom8= [HW,SERIAL]
1602 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1603
1604 ro [KNL] Mount root device read-only on boot
1605
1606 root= [KNL] Root filesystem
1607
1608 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1609 mount the root filesystem
1610
1611 rootflags= [KNL] Set root filesystem mount option string
1612
1613 rootfstype= [KNL] Set root filesystem type
1614
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001615 rootwait [KNL] Wait (indefinitely) for root device to show up.
1616 Useful for devices that are detected asynchronously
1617 (e.g. USB and MMC devices).
1618
James Morris20510f22007-10-16 23:31:32 -07001619 root_plug.vendor_id=
1620 [ROOTPLUG] Override the default vendor ID
1621
1622 root_plug.product_id=
1623 [ROOTPLUG] Override the default product ID
1624
1625 root_plug.debug=
1626 [ROOTPLUG] Enable debugging output
1627
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 rw [KNL] Mount root device read-write on boot
1629
1630 S [KNL] Run init in single mode
1631
1632 sa1100ir [NET]
1633 See drivers/net/irda/sa1100_ir.c.
1634
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1638 Format: <io>[,<timeout>[,<isapnp>]]
1639
1640 scsi_debug_*= [SCSI]
1641 See drivers/scsi/scsi_debug.c.
1642
1643 scsi_default_dev_flags=
1644 [SCSI] SCSI default device flags
1645 Format: <integer>
1646
1647 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1648 Format: <vendor>:<model>:<flags>
1649 (flags are integer value)
1650
Randy Dunlap6af66322007-11-14 16:52:25 -08001651 scsi_logging_level= [SCSI] a bit mask of logging levels
1652 See drivers/scsi/scsi_logging.h for bits. Also
1653 settable via sysctl at dev.scsi.logging_level
1654 (/proc/sys/dev/scsi/logging_level).
1655 There is also a nice 'scsi_logging_level' script in the
1656 S390-tools package, available for download at
1657 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001659 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1660 discovered. async scans them in kernel threads,
1661 allowing boot to proceed. none ignores them, expecting
1662 user space to do the scan.
1663
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 selinux [SELINUX] Disable or enable SELinux at boot time.
1665 Format: { "0" | "1" }
1666 See security/selinux/Kconfig help text.
1667 0 -- disable.
1668 1 -- enable.
1669 Default value is set via kernel config option.
1670 If enabled at boot time, /selinux/disable can be used
1671 later to disable prior to initial policy load.
1672
James Morris4e5ab4c2006-06-09 00:33:33 -07001673 selinux_compat_net =
1674 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001675 Format: { "0" | "1" }
1676 0 -- use new secmark-based packet controls
1677 1 -- use legacy packet controls
1678 Default value is 0 (preferred).
1679 Value can be changed at runtime via
1680 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001681
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001682 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684 shapers= [NET]
1685 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 sim710= [SCSI,HW]
1688 See header of drivers/scsi/sim710.c.
1689
1690 simeth= [IA-64]
1691 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 slram= [HW,MTD]
1694
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001695 slub_debug[=options[,slabs]] [MM, SLUB]
1696 Enabling slub_debug allows one to determine the
1697 culprit if slab objects become corrupted. Enabling
1698 slub_debug can create guard zones around objects and
1699 may poison objects when not in use. Also tracks the
1700 last alloc / free. For more information see
1701 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001702
1703 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001704 Determines the maximum allowed order for slabs.
1705 A high setting may cause OOMs due to memory
1706 fragmentation. For more information see
1707 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001708
1709 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001710 The minimum number of objects per slab. SLUB will
1711 increase the slab order up to slub_max_order to
1712 generate a sufficiently large slab able to contain
1713 the number of objects indicated. The higher the number
1714 of objects the smaller the overhead of tracking slabs
1715 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001716 For more information see Documentation/vm/slub.txt.
1717
1718 slub_min_order= [MM, SLUB]
1719 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001720 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001721 For more information see Documentation/vm/slub.txt.
1722
1723 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001724 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07001725 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001726 allocs to different slabs. Debug options disable
1727 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001728 For more information see Documentation/vm/slub.txt.
1729
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 smart2= [HW]
1731 Format: <io1>[,<io2>[,...,<io8>]]
1732
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001733 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001734 attempt to substitute SMP alternatives once at boot.
1735
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001736 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1737 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1738 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1739 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1740 smsc-ircc2.ircc_irq= [HW] IRQ line
1741 smsc-ircc2.ircc_dma= [HW] DMA channel
1742 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1743 0: Toshiba Satellite 1800 (GP data pin select)
1744 1: Fast pin select (default)
1745 2: ATC IRMode
1746
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 snd-ad1816a= [HW,ALSA]
1748
1749 snd-ad1848= [HW,ALSA]
1750
1751 snd-ali5451= [HW,ALSA]
1752
1753 snd-als100= [HW,ALSA]
1754
1755 snd-als4000= [HW,ALSA]
1756
1757 snd-azt2320= [HW,ALSA]
1758
1759 snd-cmi8330= [HW,ALSA]
1760
1761 snd-cmipci= [HW,ALSA]
1762
1763 snd-cs4231= [HW,ALSA]
1764
1765 snd-cs4232= [HW,ALSA]
1766
1767 snd-cs4236= [HW,ALSA]
1768
1769 snd-cs4281= [HW,ALSA]
1770
1771 snd-cs46xx= [HW,ALSA]
1772
1773 snd-dt019x= [HW,ALSA]
1774
1775 snd-dummy= [HW,ALSA]
1776
1777 snd-emu10k1= [HW,ALSA]
1778
1779 snd-ens1370= [HW,ALSA]
1780
1781 snd-ens1371= [HW,ALSA]
1782
1783 snd-es968= [HW,ALSA]
1784
1785 snd-es1688= [HW,ALSA]
1786
1787 snd-es18xx= [HW,ALSA]
1788
1789 snd-es1938= [HW,ALSA]
1790
1791 snd-es1968= [HW,ALSA]
1792
1793 snd-fm801= [HW,ALSA]
1794
1795 snd-gusclassic= [HW,ALSA]
1796
1797 snd-gusextreme= [HW,ALSA]
1798
1799 snd-gusmax= [HW,ALSA]
1800
1801 snd-hdsp= [HW,ALSA]
1802
1803 snd-ice1712= [HW,ALSA]
1804
1805 snd-intel8x0= [HW,ALSA]
1806
1807 snd-interwave= [HW,ALSA]
1808
1809 snd-interwave-stb=
1810 [HW,ALSA]
1811
1812 snd-korg1212= [HW,ALSA]
1813
1814 snd-maestro3= [HW,ALSA]
1815
1816 snd-mpu401= [HW,ALSA]
1817
1818 snd-mtpav= [HW,ALSA]
1819
1820 snd-nm256= [HW,ALSA]
1821
1822 snd-opl3sa2= [HW,ALSA]
1823
1824 snd-opti92x-ad1848=
1825 [HW,ALSA]
1826
1827 snd-opti92x-cs4231=
1828 [HW,ALSA]
1829
1830 snd-opti93x= [HW,ALSA]
1831
1832 snd-pmac= [HW,ALSA]
1833
1834 snd-rme32= [HW,ALSA]
1835
1836 snd-rme96= [HW,ALSA]
1837
1838 snd-rme9652= [HW,ALSA]
1839
1840 snd-sb8= [HW,ALSA]
1841
1842 snd-sb16= [HW,ALSA]
1843
1844 snd-sbawe= [HW,ALSA]
1845
1846 snd-serial= [HW,ALSA]
1847
1848 snd-sgalaxy= [HW,ALSA]
1849
1850 snd-sonicvibes= [HW,ALSA]
1851
1852 snd-sun-amd7930=
1853 [HW,ALSA]
1854
1855 snd-sun-cs4231= [HW,ALSA]
1856
1857 snd-trident= [HW,ALSA]
1858
1859 snd-usb-audio= [HW,ALSA,USB]
1860
1861 snd-via82xx= [HW,ALSA]
1862
1863 snd-virmidi= [HW,ALSA]
1864
1865 snd-wavefront= [HW,ALSA]
1866
1867 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001868
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1870 See Documentation/sonypi.txt
1871
1872 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1873 See Documentation/specialix.txt.
1874
1875 spia_io_base= [HW,MTD]
1876 spia_fio_base=
1877 spia_pedr=
1878 spia_peddr=
1879
1880 sscape= [HW,OSS]
1881 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001882
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1884 See Documentation/scsi/st.txt.
1885
1886 st0x= [HW,SCSI]
1887 See header of drivers/scsi/seagate.c.
1888
1889 sti= [PARISC,HW]
1890 Format: <num>
1891 Set the STI (builtin display/keyboard on the HP-PARISC
1892 machines) console (graphic card) which should be used
1893 as the initial boot-console.
1894 See also comment in drivers/video/console/sticore.c.
1895
1896 sti_font= [HW]
1897 See comment in drivers/video/console/sticore.c.
1898
1899 stifb= [HW]
1900 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1901
Greg Banks42a7fc42007-03-06 01:42:23 -08001902 sunrpc.pool_mode=
1903 [NFS]
1904 Control how the NFS server code allocates CPUs to
1905 service thread pools. Depending on how many NICs
1906 you have and where their interrupts are bound, this
1907 option will affect which CPUs will do NFS serving.
1908 Note: this parameter cannot be changed while the
1909 NFS server is running.
1910
1911 auto the server chooses an appropriate mode
1912 automatically using heuristics
1913 global a single global pool contains all CPUs
1914 percpu one pool for each CPU
1915 pernode one pool for each NUMA node (equivalent
1916 to global on non-NUMA machines)
1917
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 switches= [HW,M68k]
1921
1922 sym53c416= [HW,SCSI]
1923 See header of drivers/scsi/sym53c416.c.
1924
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001925 sysrq_always_enabled
1926 [KNL]
1927 Ignore sysrq setting - this boot parameter will
1928 neutralize any effect of /proc/sys/kernel/sysrq.
1929 Useful for debugging.
1930
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931 t128= [HW,SCSI]
1932 See header of drivers/scsi/t128.c.
1933
1934 tdfx= [HW,DRM]
1935
1936 thash_entries= [KNL,NET]
1937 Set number of hash buckets for TCP connection
1938
Len Brownf8707ec2007-08-12 00:12:54 -04001939 thermal.act= [HW,ACPI]
1940 -1: disable all active trip points in all thermal zones
1941 <degrees C>: override all lowest active trip points
1942
Len Brownc52a7412007-08-14 15:49:32 -04001943 thermal.crt= [HW,ACPI]
1944 -1: disable all critical trip points in all thermal zones
1945 <degrees C>: lower all critical trip points
1946
Len Brownf5487142007-08-12 00:12:44 -04001947 thermal.nocrt= [HW,ACPI]
1948 Set to disable actions on ACPI thermal zone
1949 critical and hot trip points.
1950
Len Brown72b33ef2007-08-12 00:12:17 -04001951 thermal.off= [HW,ACPI]
1952 1: disable ACPI thermal control
1953
Len Browna70cdc52007-08-12 00:12:35 -04001954 thermal.psv= [HW,ACPI]
1955 -1: disable all passive trip points
1956 <degrees C>: override all passive trip points to this value
1957
Len Brown730ff342007-08-12 00:12:26 -04001958 thermal.tzp= [HW,ACPI]
1959 Specify global default ACPI thermal zone polling rate
1960 <deci-seconds>: poll all this frequency
1961 0: no polling (default)
1962
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 time Show timing data prefixed to each printk message line
Randy Dunlape84845c2007-07-15 23:40:25 -07001964 [deprecated, see 'printk.time']
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965
1966 tipar.timeout= [HW,PPT]
1967 Set communications timeout in tenths of a second
1968 (default 15).
1969
1970 tipar.delay= [HW,PPT]
1971 Set inter-bit delay in microseconds (default 10).
1972
1973 tmc8xx= [HW,SCSI]
1974 See header of drivers/scsi/seagate.c.
1975
1976 tmscsim= [HW,SCSI]
1977 See comment before function dc390_setup() in
1978 drivers/scsi/tmscsim.c.
1979
1980 tp720= [HW,PS2]
1981
1982 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001983 Format:
1984 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1985
Randy Dunlapa9913042005-10-23 12:57:11 -07001986 turbografx.map[2|3]= [HW,JOY]
1987 TurboGraFX parallel port interface
1988 Format:
1989 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 See also Documentation/input/joystick-parport.txt
1991
1992 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1993 See header of drivers/scsi/u14-34f.c.
1994
1995 uart401= [HW,OSS]
1996 Format: <io>,<irq>
1997
1998 uart6850= [HW,OSS]
1999 Format: <io>,<irq>
2000
Alan Stern5f8364b2006-12-05 16:29:55 -05002001 uhci-hcd.ignore_oc=
2002 [USB] Ignore overcurrent events (default N).
2003 Some badly-designed motherboards generate lots of
2004 bogus events, for ports that aren't wired to
2005 anything. Set this parameter to avoid log spamming.
2006 Note that genuine overcurrent events won't be
2007 reported either.
2008
Alan Sternb5e795f2007-02-20 15:00:53 -05002009 usbcore.autosuspend=
2010 [USB] The autosuspend time delay (in seconds) used
2011 for newly-detected USB devices (default 2). This
2012 is the time required before an idle device will be
2013 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002014 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002015
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 usbhid.mousepoll=
2017 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002018
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002019 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002020 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002021 vdso=1: enable VDSO (default)
2022 vdso=0: disable VDSO mapping
2023
Roland McGrathaf65d642008-01-30 13:30:43 +01002024 vdso32= [X86-32,X86-64]
2025 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2026 vdso32=1: enable 32-bit VDSO (default)
2027 vdso32=0: disable 32-bit VDSO mapping
2028
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002029 vector= [IA-64,SMP]
2030 vector=percpu: enable percpu vector domain
2031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 video= [FB] Frame buffer configuration
2033 See Documentation/fb/modedb.txt.
2034
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002035 vga= [BOOT,X86-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07002036 See Documentation/i386/boot.txt and
2037 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038 Use vga=ask for menu.
2039 This is actually a boot loader parameter; the value is
2040 passed to the kernel using a special protocol.
2041
Randy Dunlapa9913042005-10-23 12:57:11 -07002042 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 size of <nn>. This can be used to increase the
2044 minimum size (128MB on x86). It can also be used to
2045 decrease the size and leave more room for directly
2046 mapped kernel RAM.
2047
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002048 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2049 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002051 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2052 Format: <command>
2053
2054 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2055 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002056
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 waveartist= [HW,OSS]
2058 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002059
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060 wd33c93= [HW,SCSI]
2061 See header of drivers/scsi/wd33c93.c.
2062
2063 wd7000= [HW,SCSI]
2064 See header of drivers/scsi/wd7000.c.
2065
2066 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002067 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068
2069 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2070 xd_geo= See header of drivers/block/xd.c.
2071
2072 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002073 Format:
2074 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075
Andi Kleena62eaf12006-02-16 23:41:58 +01002076 norandmaps Don't use address space randomization
2077 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2078
Randy Dunlapa9913042005-10-23 12:57:11 -07002079______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
2081TODO:
2082
2083 Add documentation for ALSA options.
2084 Add more DRM drivers.