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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.
David Brownell77437fd2008-07-23 21:28:33 -070090 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700100 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700103 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
106In addition, the following text indicates that the option:
107
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
111
112Parameters denoted with BOOT are actually interpreted by the boot
113loader, and have no meaning to the kernel directly.
114Do not modify the syntax of boot loader parameters without extreme
Uwe Hermann71cced62008-10-20 09:32:21 -0700115need or coordination with <Documentation/x86/i386/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
Karsten Weiss55588702007-02-13 13:26:21 +0100117There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700118See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100119
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121a trailing = on the name of any parameter states that that parameter will
122be entered as an environment variable, whereas its absence indicates that
123it will appear as a kernel argument readable via /proc/cmdline by programs
124running once the system is up.
125
jens m. noedler9c4751f2006-09-29 02:00:27 -0700126The number of kernel parameters is not limited, but the length of the
127complete command line (parameters including spaces etc.) is limited to
128a fixed number of characters. This limit depends on the architecture
129and is between 256 and 4096 characters. It is defined in the file
130./include/asm/setup.h as COMMAND_LINE_SIZE.
131
132
Bernhard Walle03d926f2007-03-06 02:29:44 -0800133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700135 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700140 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 strictly ACPI specification compliant.
142
Randy Dunlap53471122008-03-12 18:10:51 -0400143 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Len Browna1fdcc02007-03-11 03:26:14 -0400145 acpi_apic_instance= [ACPI, IOAPIC]
146 Format: <int>
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400149 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400150
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 acpi_sleep= [HW,ACPI] Sleep options
Shaohua Libdfe6b72008-07-23 21:28:41 -0700152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
Pavel Machek23b168d2008-02-05 19:27:12 +0100153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
161 used by default).
Randy Dunlapa9913042005-10-23 12:57:11 -0700162
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700164 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Randy Dunlapa9913042005-10-23 12:57:11 -0700166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
168 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
Randy Dunlapa9913042005-10-23 12:57:11 -0700170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
172 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
Randy Dunlapa9913042005-10-23 12:57:11 -0700174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 Format: <irq>,<irq>...
177
Randy Dunlapa9913042005-10-23 12:57:11 -0700178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 Format: <irq>,<irq>...
180
Len Brown67effe82007-07-26 00:50:06 -0400181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182
Len Browna1f9e652006-01-25 23:47:36 -0500183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
185
Len Brownae00d812007-05-29 18:43:33 -0400186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
191 acpi_serialize [HW,ACPI] force serialization of AML methods
192
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
199 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
203 acpi_backlight=video
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
207
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
211 See above.
212
Zhang Ruif9891062007-04-24 13:53:22 +0800213 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700215 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 1: enable, 0: disable. It is useful for boot time
217 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800218 via /sys/module/acpi/parameters/debug_layer.
219 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
220 Available bits (add the numbers together) to enable debug output
221 for specific parts of the ACPI subsystem:
222 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
223 0x10 namespace 0x20 parser 0x40 dispatcher
224 0x80 executer 0x100 resources 0x200 acpica debugger
225 0x400 os services 0x800 acpica disassembler.
226 The number can be in decimal or prefixed with 0x in hex.
227 Warning: Many of these options can produce a lot of
228 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
Zhang Ruif9891062007-04-24 13:53:22 +0800230 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700232 Each bit of the <int> indicates an ACPI debug level,
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200233 which corresponds to the level in an ACPI_DEBUG_PRINT
234 statement. After system has booted up, this mask
235 can be set via /sys/module/acpi/parameters/debug_level.
236
237 CONFIG_ACPI_DEBUG must be enabled for this to produce
238 any output. The number can be in decimal or prefixed
239 with 0x in hex. Some of these options produce so much
240 output that the system is unusable.
241
242 The following global components are defined by the
243 ACPI CA:
244 0x01 error
245 0x02 warn
246 0x04 init
247 0x08 debug object
248 0x10 info
249 0x20 init names
250 0x40 parse
251 0x80 load
252 0x100 dispatch
253 0x200 execute
254 0x400 names
255 0x800 operation region
256 0x1000 bfield
257 0x2000 tables
258 0x4000 values
259 0x8000 objects
260 0x10000 resources
261 0x20000 user requests
262 0x40000 package
263 The number can be in decimal or prefixed with 0x in hex.
264 Warning: Many of these options can produce a lot of
265 output and make your system unusable. Be very careful.
Zhang Ruif9891062007-04-24 13:53:22 +0800266
Zhao Yakuif5adfaa2008-08-11 14:57:50 +0800267 acpi.power_nocheck= [HW,ACPI]
268 Format: 1/0 enable/disable the check of power state.
269 On some bogus BIOS the _PSC object/_STA object of
270 power resource can't return the correct device power
271 state. In such case it is unneccessary to check its
272 power state again in power transition.
273 1 : disable the power state check
274
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700275 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700276 Override the pmtimer bug detection: force the kernel
277 to assume that this machine's pmtimer latches its value
278 and always returns good values.
279
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000280 agp= [AGP]
281 { off | try_unsupported }
282 off: disable AGP support
283 try_unsupported: try to drive unsupported chipsets
284 (may crash computer or cause data corruption)
285
Chuck Ebbert66759a02005-09-12 18:49:25 +0200286 enable_timer_pin_1 [i386,x86-64]
287 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700288 Can be useful to work around chipset bugs
289 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200290 The kernel tries to set a reasonable default.
291
292 disable_timer_pin_1 [i386,x86-64]
293 Disable PIN 1 of APIC timer
294 Can be useful to work around chipset bugs.
295
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 ad1848= [HW,OSS]
297 Format: <io>,<irq>,<dma>,<dma2>,<type>
298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 advansys= [HW,SCSI]
300 See header of drivers/scsi/advansys.c.
301
302 advwdt= [HW,WDT] Advantech WDT
303 Format: <iostart>,<iostop>
304
305 aedsp16= [HW,OSS] Audio Excel DSP 16
306 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
307 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700308
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 aha152x= [HW,SCSI]
310 See Documentation/scsi/aha152x.txt.
311
312 aha1542= [HW,SCSI]
313 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
314
315 aic7xxx= [HW,SCSI]
316 See Documentation/scsi/aic7xxx.txt.
317
318 aic79xx= [HW,SCSI]
319 See Documentation/scsi/aic79xx.txt.
320
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200321 amd_iommu= [HW,X86-84]
322 Pass parameters to the AMD IOMMU driver in the system.
323 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200324 isolate - enable device isolation (each device, as far
325 as possible, will get its own protection
326 domain)
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900327 fullflush - enable flushing of IO/TLB entries when
328 they are unmapped. Otherwise they are
329 flushed before they will be reused, which
330 is a lot of faster
331
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200332 amd_iommu_size= [HW,X86-64]
333 Define the size of the aperture for the AMD IOMMU
334 driver. Possible values are:
335 '32M', '64M' (default), '128M', '256M', '512M', '1G'
336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
339 Format: <a>,<b>
340 See also Documentation/kernel/input/joystick.txt
341
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
346
Randy Dunlapa9913042005-10-23 12:57:11 -0700347 apc= [HW,SPARC]
348 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 Format: noidle
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
353
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700354 apic= [APIC,i386] Advanced Programmable Interrupt Controller
355 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700359
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700361 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
364 Format: <io>,<irq>,<nodeID>
365
366 ataflop= [HW,M68k]
367
368 atarimouse= [HW,MOUSE] Atari Mouse
369
370 atascsi= [HW,SCSI] Atari SCSI
371
372 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
373 EzKey and similar keyboards
374
375 atkbd.reset= [HW] Reset keyboard during initialization
376
Randy Dunlapa9913042005-10-23 12:57:11 -0700377 atkbd.set= [HW] Select keyboard code set
378 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
381 keyboards
382
383 atkbd.softraw= [HW] Choose between synthetic and real raw mode
384 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700385
386 atkbd.softrepeat= [HW]
387 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 autotest [IA64]
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 baycom_epp= [HW,AX25]
392 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700393
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
395 Format: <io>,<mode>
396 See header of drivers/net/hamradio/baycom_par.c.
397
Randy Dunlapa9913042005-10-23 12:57:11 -0700398 baycom_ser_fdx= [HW,AX25]
399 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 Format: <io>,<irq>,<mode>[,<baud>]
401 See header of drivers/net/hamradio/baycom_ser_fdx.c.
402
Randy Dunlapa9913042005-10-23 12:57:11 -0700403 baycom_ser_hdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 Format: <io>,<irq>,<mode>
406 See header of drivers/net/hamradio/baycom_ser_hdx.c.
407
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700408 boot_delay= Milliseconds to delay each printk during boot.
409 Values larger than 10 seconds (10000) are changed to
410 no delay (0).
411 Format: integer
412
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700413 bootmem_debug [KNL] Enable bootmem allocator debug messages.
414
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700416 bttv.radio= Most important insmod options are available as
417 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
419 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
420
421 BusLogic= [HW,SCSI]
422 See drivers/scsi/BusLogic.c, comment before function
423 BusLogic_ParseDriverOptions().
424
425 c101= [NET] Moxa C101 synchronous serial card
426
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700427 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 Sometimes CPU hardware bugs make them report the cache
429 size incorrectly. The kernel will attempt work arounds
430 to fix known problems, but for some CPUs it is not
431 possible to determine what the correct size should be.
432 This option provides an override for these situations.
433
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200434 security= [SECURITY] Choose a security module to enable at boot.
435 If this boot parameter is not specified, only the first
436 security module asking for security registration will be
437 loaded. An invalid security module name will be treated
438 as if no module has been chosen.
439
James Morris20510f22007-10-16 23:31:32 -0700440 capability.disable=
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
445
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Paul Menage8bab8dd2008-04-04 14:29:57 -0700449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
452
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700460 Value can be changed at runtime via
461 /selinux/checkreqprot.
462
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100463 cio_ignore= [S390]
464 See Documentation/s390/CommonIO for details.
465
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700467 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200468 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700469 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200470 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 Format: { pit | tsc | cyclone | pmtmr }
472
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700473 clocksource= [GENERIC_TIME] Override the default clocksource
474 Format: <string>
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
478 the platform:
479 [all] jiffies (this is the base, fallback clocksource)
480 [ACPI] acpi_pm
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
483 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700484 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700485 scx200_hrt on Geode; cyclone on IBM x440
486 [MIPS] MIPS
487 [PARISC] cr16
488 [S390] tod
489 [SH] SuperH
490 [SPARC64] tick
491 [X86-64] hpet,tsc
492
Andi Kleenac72e782008-01-30 13:33:21 +0100493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 include/asm-x86/cpufeature.h for the valid bit numbers.
496 Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
498 ones should be.
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
504 some critical bits.
505
Arjan van de Vena25bd942008-01-30 13:33:08 +0100506 code_bytes [IA32/X86_64] How many bytes of object code to print
507 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100508 Range: 0 - 8192
509 Default: 64
510
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200511 hpet= [X86-32,HPET] option to control HPET usage
512 Format: { enable (default) | disable | force }
513 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100514 force: allow force enabled of undocumented chips (ICH4,
515 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700518 Format:
519 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520
521 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
522 Format: <io>[,<irq>]
523
Randy Dunlapa9913042005-10-23 12:57:11 -0700524 com90xx= [HW,NET]
525 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 Format: <io>[,<irq>[,<memstart>]]
527
528 condev= [HW,S390] console device
529 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700530
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 console= [KNL] Output console device and options.
532
533 tty<n> Use the virtual console device <n>.
534
535 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800536 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800538 the form "bbbbpnf", where "bbbb" is the baud rate,
539 "p" is parity ("n", "o", or "e"), "n" is number of
540 bits, and "f" is flow control ("r" for RTS or
541 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800543 See Documentation/serial-console.txt for more
544 information. See
545 Documentation/networking/netconsole.txt for an
546 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700548 uart[8250],io,<addr>[,options]
549 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 Start an early, polled-mode console on the 8250/16550
551 UART at the specified I/O port or MMIO address,
552 switching to the matching ttyS device later. The
553 options are the same as for ttyS, above.
554
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700555 If the device connected to the port is not a TTY but a braille
556 device, prepend "brl," before the device type, for instance
557 console=brl,ttyS0
558 For now, only VisioBraille is supported.
559
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700560 earlycon= [KNL] Output early console device and options.
561 uart[8250],io,<addr>[,options]
562 uart[8250],mmio,<addr>[,options]
563 Start an early, polled-mode console on the 8250/16550
564 UART at the specified I/O port or MMIO address.
565 The options are the same as for ttyS, above.
566
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700567 no_console_suspend
568 [HW] Never suspend the console
569 Disable suspending of consoles during suspend and
570 hibernate operations. Once disabled, debugging
571 messages can reach various consoles while the rest
572 of the system is being put to sleep (ie, while
573 debugging driver suspend/resume hooks). This may
574 not work reliably with all consoles, but is known
575 to work with serial and VGA consoles.
576
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700578 Format:
579 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700581 crashkernel=nn[KMG]@ss[KMG]
582 [KNL] Reserve a chunk of physical memory to
583 hold a kernel to switch to with kexec on panic.
584
Bernhard Wallefb391592007-10-18 23:41:02 -0700585 crashkernel=range1:size1[,range2:size2,...][@offset]
586 [KNL] Same as above, but depends on the memory
587 in the running system. The syntax of range is
588 start-[end] where start and end are both
589 a memory unit (amount[KMG]). See also
590 Documentation/kdump/kdump.txt for a example.
591
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 cs4232= [HW,OSS]
593 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
594
595 cs89x0_dma= [HW,NET]
596 Format: <dma>
597
598 cs89x0_media= [HW,NET]
599 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700600
Randy Dunlapa9913042005-10-23 12:57:11 -0700601 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 See header of drivers/s390/block/dasd_devmap.c.
603
604 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
605 (one device per port)
606 Format: <port#>,<type>
607 See also Documentation/input/joystick-parport.txt
608
609 debug [KNL] Enable kernel debugging (events log level).
610
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700611 debug_locks_verbose=
612 [KNL] verbose self-tests
613 Format=<0|1>
614 Print debugging info while doing the locking API
615 self-tests.
616 We default to 0 (no extra messages), setting it to
617 1 will print _a lot_ more information - normally
618 only useful to kernel developers.
619
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700620 debug_objects [KNL] Enable object debugging
621
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200622 debugpat [X86] Enable PAT debugging
623
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200624 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 Format: <area>[,<node>]
626 See also Documentation/networking/decnet.txt.
627
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000628 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700629 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
630 Change the default blue palette of the console.
631 This is a 16-member array composed of values
632 ranging from 0-255.
633
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000634 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700635 Format: <green0>,<green1>,<green2>,...,<green15>
636 Change the default green palette of the console.
637 This is a 16-member array composed of values
638 ranging from 0-255.
639
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000640 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700641 Format: <red0>,<red1>,<red2>,...,<red15>
642 Change the default red palette of the console.
643 This is a 16-member array composed of values
644 ranging from 0-255.
645
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000646 vt.default_utf8=
647 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700648 Format=<0|1>
649 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000650 Default is 1, i.e. UTF-8 mode is enabled for all
651 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700652
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 dhash_entries= [KNL]
654 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700655
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 digi= [HW,SERIAL]
657 IO parameters + enable/disable command.
658
659 digiepca= [HW,SERIAL]
660 See drivers/char/README.epca and
661 Documentation/digiepca.txt.
662
Yinghai Lu95ffa242008-04-29 03:52:33 -0700663 disable_mtrr_cleanup [X86]
664 enable_mtrr_cleanup [X86]
665 The kernel tries to adjust MTRR layout from continuous
666 to discrete, to make X server driver able to add WB
667 entry later. This parameter enables/disables that.
668
669 mtrr_chunk_size=nn[KMG] [X86]
670 used for mtrr cleanup. It is largest continous chunk
671 that could hold holes aka. UC entries.
672
673 mtrr_gran_size=nn[KMG] [X86]
Yinghai Lu12031a62008-05-02 02:40:22 -0700674 Used for mtrr cleanup. It is granularity of mtrr block.
675 Default is 1.
676 Large value could prevent small alignment from
677 using up MTRRs.
678
679 mtrr_spare_reg_nr=n [X86]
680 Format: <integer>
681 Range: 0,7 : spare reg number
682 Default : 1
683 Used for mtrr cleanup. It is spare mtrr entries number.
684 Set to 2 or more if your graphical card needs more.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700685
Yinghai Lu093af8d2008-01-30 13:33:32 +0100686 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100687 By default the kernel will trim any uncacheable
688 memory out of your available memory pool based on
689 MTRR settings. This parameter disables that behavior,
690 possibly causing your machine to run very slowly.
691
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 dmasound= [HW,OSS] Sound subsystem buffers
693
694 dscc4.setup= [NET]
695
696 dtc3181e= [HW,SCSI]
697
Robin Getz0ae53642007-10-09 17:24:49 +0800698 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 earlyprintk=vga
700 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700701 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
Randy Dunlapa9913042005-10-23 12:57:11 -0700703 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 takes over.
705
Yinghai Lu5c059172008-07-24 17:29:40 -0700706 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707
708 Currently only ttyS0 and ttyS1 are supported.
709
710 Interaction with the standard serial driver is not
711 very good.
712
713 The VGA output is eventually overwritten by the real
714 console.
715
716 eata= [HW,SCSI]
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700719 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 eisa_irq_edge= [PARISC,HW]
722 See header of drivers/parisc/eisa.c.
723
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700724 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700726 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727
728 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800729 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700730 See Documentation/block/as-iosched.txt and
731 Documentation/block/deadline-iosched.txt for details.
732
Simon Hormane515a0d2008-10-18 20:28:27 -0700733 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700734 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800735 image elf header. Generally kexec loader will
736 pass this option to capture kernel.
737 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
739 enforcing [SELINUX] Set initial enforcing status.
740 Format: {"0" | "1"}
741 See security/selinux/Kconfig help text.
742 0 -- permissive (log only, no denials).
743 1 -- enforcing (deny and log).
744 Default value is 0.
745 Value can be changed at runtime via /selinux/enforce.
746
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 es1371= [HW,OSS]
748 Format: <spdif>,[<nomix>,[<amplifier>]]
749 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700750
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 ether= [HW,NET] Ethernet cards parameters
752 This option is obsoleted by the "netdev=" option, which
753 has equivalent usage. See its documentation for details.
754
755 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
756 Format: <io>[,<irq>]
757
Akinobu Mitade1ba092006-12-08 02:39:42 -0800758 failslab=
759 fail_page_alloc=
760 fail_make_request=[KNL]
761 General fault injection mechanism.
762 Format: <interval>,<probability>,<space>,<times>
763 See also /Documentation/fault-injection/.
764
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 fd_mcs= [HW,SCSI]
766 See header of drivers/scsi/fd_mcs.c.
767
768 fdomain= [HW,SCSI]
769 See header of drivers/scsi/fdomain.c.
770
771 floppy= [HW]
772 See Documentation/floppy.txt.
773
Alex Chiangf13ae302008-05-08 14:03:23 -0600774 force_pal_cache_flush
775 [IA-64] Avoid check_sal_cache_flush which may hang on
776 buggy SAL_CACHE_FLUSH implementations. Using this
777 parameter will force ia64_sal_cache_flush to call
778 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 gamecon.map[2|3]=
781 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
782 support via parallel port (up to 5 devices per port)
783 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
784 See also Documentation/input/joystick-parport.txt
785
786 gamma= [HW,DRM]
787
Yinghai Luaaf23042008-01-30 13:33:09 +0100788 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 Format: off | on
790 default: on
791
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 gdth= [HW,SCSI]
793 See header of drivers/scsi/gdth.c.
794
795 gpt [EFI] Forces disk with valid GPT signature but
796 invalid Protective MBR to be treated as GPT.
797
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 gvp11= [HW,SCSI]
799
800 hashdist= [KNL,NUMA] Large hashes allocated during boot
801 are distributed across NUMA nodes. Defaults on
802 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700803 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
805 hcl= [IA-64] SGI's Hardware Graph compatibility layer
806
807 hd= [EIDE] (E)IDE hard drive subsystem geometry
808 Format: <cyl>,<head>,<sect>
809
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
811 size of <nn>. This works even on boxes that have no
812 highmem otherwise. This also works to reduce highmem
813 size on bigger boxes.
814
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800815 highres= [KNL] Enable/disable high resolution timer mode.
816 Valid parameters: "on", "off"
817 Default: "on"
818
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 hisax= [HW,ISDN]
820 See Documentation/isdn/README.HiSax.
821
Andi Kleenb4718e62008-07-23 21:27:51 -0700822 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
823 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700824 On x86-64 and powerpc, this option can be specified
825 multiple times interleaved with hugepages= to reserve
826 huge pages of different sizes. Valid pages sizes on
827 x86-64 are 2M (when the CPU supports "pse") and 1G
828 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700829 Note that 1GB pages can only be allocated at boot time
830 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700831 default_hugepagesz=
832 [same as hugepagesz=] The size of the default
833 HugeTLB page size. This is the size represented by
834 the legacy /proc/ hugepages APIs, used for SHM, and
835 default size when mounting hugetlbfs filesystems.
836 Defaults to the default architecture's huge page size
837 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838
Paul Mundt6902aa82008-09-21 17:14:42 +0900839 hlt [BUGS=ARM,SH]
840
Jiri Kosina36d95732008-10-06 02:51:09 -0400841 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200843 i8042.dumbkbd [HW] Pretend that controller can only read data from
844 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 (Don't attempt to blink the leds)
846 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500847 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400848 i8042.noloop [HW] Disable the AUX Loopback command while probing
849 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 i8042.nomux [HW] Don't check presence of an active multiplexing
851 controller
852 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
853 controllers
854 i8042.panicblink=
855 [HW] Frequency with which keyboard LEDs should blink
856 when kernel panics (default is 0.5 sec)
857 i8042.reset [HW] Reset the controller during init and cleanup
858 i8042.unlock [HW] Unlock (ignore) the keylock
859
860 i810= [HW,DRM]
861
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700862 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
863 indicates that the driver is running on unsupported
864 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
866 does not match list of supported models.
867 i8k.power_status
868 [HW] Report power status in /proc/i8k
869 (disabled by default)
870 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
871 capability is set.
872
873 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
874 See Documentation/mca.txt.
875
876 icn= [HW,ISDN]
877 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
878
879 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200880 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100881 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100884 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
Andi Kleenf039b752007-05-02 19:27:12 +0200886 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800887 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200888 Poll forces a polling idle loop that can slightly improves the performance
889 of waking up a idle CPU, but will use a lot of power and make the system
890 run hot. Not recommended.
891 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
892 to not use it because it doesn't save as much power as a normal idle
893 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
894 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800895 idle=halt. Halt is forced to be used for CPU idle.
896 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800897 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700898
Denis Cheng594765a2008-02-06 02:57:49 +0100899 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
900 Claim all unknown PCI IDE storage controllers.
901
Ingo Molnar792908222006-12-06 20:40:51 -0800902 ignore_loglevel [KNL]
903 Ignore loglevel setting - this will print /all/
904 kernel messages to the console. Useful for debugging.
905
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 ihash_entries= [KNL]
907 Set number of hash buckets for inode cache.
908
909 in2000= [HW,SCSI]
910 See header of drivers/scsi/in2000.c.
911
912 init= [KNL]
913 Format: <full_path>
914 Run specified binary instead of /sbin/init as init
915 process.
916
917 initcall_debug [KNL] Trace initcalls as they are executed. Useful
918 for working out where the kernel is dying during
919 startup.
920
921 initrd= [BOOT] Specify the location of the initial ramdisk
922
923 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
924 Format: <irq>
925
926 inttest= [IA64]
927
Pavel Machekb552da82008-03-19 15:58:11 +0100928 iommu= [x86]
929 off
930 force
931 noforce
932 biomerge
933 panic
934 nopanic
935 merge
936 nomerge
937 forcesac
938 soft
939
940
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700941 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
942 off
943 Disable intel iommu driver.
944 igfx_off [Default Off]
945 By default, gfx is mapped as normal device. If a gfx
946 device has a dedicated DMAR unit, the DMAR unit is
947 bypassed by not enabling DMAR with this option. In
948 this case, gfx device will use physical address for
949 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700950 forcedac [x86_64]
951 With this option iommu will not optimize to look
952 for io virtual address below 32 bit forcing dual
953 address cycle on pci bus for cards supporting greater
954 than 32 bit addressing. The default is to look
955 for translation below 32 bit and if not available
956 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800957 strict [Default Off]
958 With this option on every unmap_single operation will
959 result in a hardware IOTLB flush operation as opposed
960 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700961
Rene Hermanb02aae92008-01-30 13:30:05 +0100962 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100963 0x80
964 Standard port 0x80 based delay
965 0xed
966 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100967 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100968 Simple two microseconds delay
969 none
970 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100971
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 io7= [HW] IO7 for Marvel based alpha systems
973 See comment before marvel_specify_io7 in
974 arch/alpha/kernel/core_marvel.c.
975
976 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400977 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978
979 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700980 See comment before ip2_setup() in
981 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982
983 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
984 See header of drivers/scsi/ips.c.
985
Simon Horman72c4a132006-09-13 19:57:18 -0700986 ports= [IP_VS_FTP] IPVS ftp helper module
987 Default is 21.
988 Up to 8 (IP_VS_APP_MAX_PORTS) ports
989 may be specified.
990 Format: <port>,<port>....
991
Alan Cox200803d2005-06-28 20:45:18 -0700992 irqfixup [HW]
993 When an interrupt is not handled search all handlers
994 for it. Intended to get systems with badly broken
995 firmware running.
996
997 irqpoll [HW]
998 When an interrupt is not handled search all handlers
999 for it. Also check all handlers each timer
1000 interrupt. Intended to get systems with badly broken
1001 firmware running.
1002
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001004 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
1006 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001007 Format:
1008 <cpu number>,...,<cpu number>
1009 or
Li Zefanb225d442008-11-06 12:53:39 -08001010 <cpu number>-<cpu number>
1011 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001012 or a mixture
1013 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001014
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 This option can be used to specify one or more CPUs
1016 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001017 algorithms. You can move a process onto or off an
1018 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 <cpu number> begins at 0 and the maximum value is
1020 "number of CPUs in system - 1".
1021
1022 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001023 alternative -- manually setting the CPU mask of all
1024 tasks in the system -- can cause problems and
1025 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026
Randy Dunlapa9913042005-10-23 12:57:11 -07001027 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028
1029 js= [HW,JOY] Analog joystick
1030 See Documentation/input/joystick.txt.
1031
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001032 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001033 specifies the amount of memory usable by the kernel
1034 for non-movable allocations. The requested amount is
1035 spread evenly throughout all nodes in the system. The
1036 remaining memory in each node is used for Movable
1037 pages. In the event, a node is too small to have both
1038 kernelcore and Movable pages, kernelcore pages will
1039 take priority and other nodes will have a larger number
1040 of kernelcore pages. The Movable zone is used for the
1041 allocation of pages that may be reclaimed or moved
1042 by the page migration subsystem. This means that
1043 HugeTLB pages may not be allocated from this zone.
1044 Note that allocations like PTEs-from-HighMem still
1045 use the HighMem zone if it exists, and the Normal
1046 zone if it does not.
1047
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001048 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001049 is similar to kernelcore except it specifies the
1050 amount of memory used for migratable allocations.
1051 If both kernelcore and movablecore is specified,
1052 then kernelcore will be at *least* the specified
1053 value but may be more. If movablecore on its own
1054 is specified, the administrator must be careful
1055 that the amount of memory usable for all allocations
1056 is not too small.
1057
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 keepinitrd [HW,ARM]
1059
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001060 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 in oops dumps.
1062
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001063 kgdboc= [HW] kgdb over consoles.
1064 Requires a tty driver that supports console polling.
1065 (only serial suported for now)
1066 Format: <serial_device>[,baud]
1067
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001068 kmac= [MIPS] korina ethernet MAC address.
1069 Configure the RouterBoard 532 series on-chip
1070 Ethernet adapter MAC address.
1071
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 l2cr= [PPC]
1073
Robert Brosea78bfbf2008-03-29 07:20:23 +11001074 l3cr= [PPC]
1075
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001076 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001077 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001079 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001080 C2 power state.
1081
FD Camifcb71f62008-01-06 19:08:56 +01001082 libata.dma= [LIBATA] DMA control
1083 libata.dma=0 Disable all PATA and SATA DMA
1084 libata.dma=1 PATA and SATA Disk DMA only
1085 libata.dma=2 ATAPI (CDROM) DMA only
1086 libata.dma=4 Compact Flash DMA only
1087 Combinations also work, so libata.dma=3 enables DMA
1088 for disks and CDROMs, but not CFs.
1089
Dave Jones78e70c22007-09-27 11:50:13 -04001090 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1091 when set.
1092 Format: <int>
1093
Tejun Heo33267322008-02-13 09:15:09 +09001094 libata.force= [LIBATA] Force configurations. The format is comma
1095 separated list of "[ID:]VAL" where ID is
1096 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1097 matching port, link or device. Basically, it matches
1098 the ATA ID string printed on console by libata. If
1099 the whole ID part is omitted, the last PORT and DEVICE
1100 values are used. If ID hasn't been specified yet, the
1101 configuration applies to all ports, links and devices.
1102
1103 If only DEVICE is omitted, the parameter applies to
1104 the port and all links and devices behind it. DEVICE
1105 number of 0 either selects the first device or the
1106 first fan-out link behind PMP device. It does not
1107 select the host link. DEVICE number of 15 selects the
1108 host link and device attached to it.
1109
1110 The VAL specifies the configuration to force. As long
1111 as there's no ambiguity shortcut notation is allowed.
1112 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1113 The following configurations can be forced.
1114
1115 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1116 Any ID with matching PORT is used.
1117
1118 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1119
1120 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1121 udma[/][16,25,33,44,66,100,133] notation is also
1122 allowed.
1123
1124 * [no]ncq: Turn on or off NCQ.
1125
Tejun Heo05944bd2008-08-13 20:19:09 +09001126 * nohrst, nosrst, norst: suppress hard, soft
1127 and both resets.
1128
Tejun Heo33267322008-02-13 09:15:09 +09001129 If there are multiple matching configurations changing
1130 the same attribute, the last one is used.
1131
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 load_ramdisk= [RAM] List of ramdisks to load from floppy
1133 See Documentation/ramdisk.txt.
1134
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001135 lockd.nlm_grace_period=P [NFS] Assign grace period.
1136 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001138 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1139 Format: <integer>
1140
1141 lockd.nlm_timeout=T [NFS] Assign timeout value.
1142 Format: <integer>
1143
1144 lockd.nlm_udpport=M [NFS] Assign UDP port.
1145 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146
1147 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1148 Format: <irq>
1149
1150 loglevel= All Kernel Messages with a loglevel smaller than the
1151 console loglevel will be printed to the console. It can
1152 also be changed with klogd or other programs. The
1153 loglevels are defined as follows:
1154
1155 0 (KERN_EMERG) system is unusable
1156 1 (KERN_ALERT) action must be taken immediately
1157 2 (KERN_CRIT) critical conditions
1158 3 (KERN_ERR) error conditions
1159 4 (KERN_WARNING) warning conditions
1160 5 (KERN_NOTICE) normal but significant condition
1161 6 (KERN_INFO) informational
1162 7 (KERN_DEBUG) debug-level messages
1163
1164 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001165 Format: { n | nk | nM }
1166 n must be a power of two. The default size
1167 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
Randy Dunlapaccaa242007-10-16 01:29:37 -07001169 logo.nologo [FB] Disables display of the built-in Linux logo.
1170 This may be used to provide more screen space for
1171 kernel log messages and is useful when debugging
1172 kernel boot problems.
1173
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 lp=0 [LP] Specify parallel ports to use, e.g,
1175 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1176 lp=reset first parallel port). 'lp=0' disables the
1177 lp=auto printer driver. 'lp=reset' (which can be
1178 specified in addition to the ports) causes
1179 attached printers to be reset. Using
1180 lp=port1,port2,... specifies the parallel ports
1181 to associate lp devices with, starting with
1182 lp0. A port specification may be 'none' to skip
1183 that lp device, or a parport name such as
1184 'parport0'. Specifying 'lp=auto' instead of a
1185 port specification list means that device IDs
1186 from each port should be examined, to see if
1187 an IEEE 1284-compliant printer is attached; if
1188 so, the driver will manage that printer.
1189 See also header of drivers/char/lp.c.
1190
1191 lpj=n [KNL]
1192 Sets loops_per_jiffy to given constant, thus avoiding
1193 time-consuming boot-time autodetection (up to 250 ms per
1194 CPU). 0 enables autodetection (default). To determine
1195 the correct value for your kernel, boot with normal
1196 autodetection and see what value is printed. Note that
1197 on SMP systems the preset will be applied to all CPUs,
1198 which is likely to cause problems if your CPUs need
1199 significantly divergent settings. An incorrect value
1200 will cause delays in the kernel to be wrong, leading to
1201 unpredictable I/O errors and other breakage. Although
1202 unlikely, in the extreme case this might damage your
1203 hardware.
1204
1205 ltpc= [NET]
1206 Format: <io>,<irq>,<dma>
1207
Randy Dunlapa9913042005-10-23 12:57:11 -07001208 mac5380= [HW,SCSI] Format:
1209 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210
Randy Dunlapa9913042005-10-23 12:57:11 -07001211 machvec= [IA64] Force the use of a particular machine-vector
1212 (machvec) in a generic kernel.
1213 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214
Randy Dunlapa9913042005-10-23 12:57:11 -07001215 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 be mounted
1217 Format: <1-256>
1218
1219 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001220 should make use of. maxcpus=n : n >= 0 limits the
1221 kernel to using 'n' processors. n=0 is a special case,
1222 it is equivalent to "nosmp", which also disables
1223 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224
Bob Picco2b2c3752005-06-29 18:00:00 -07001225 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1226 equal to this physical address is ignored.
1227
Randy Dunlapa9913042005-10-23 12:57:11 -07001228 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 Should be between 1 and 2^32-1.
1230
1231 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001232 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 Should be between 1 and 16384.
1234
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 mcatest= [IA-64]
1236
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001237 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238
Uwe Hermann71cced62008-10-20 09:32:21 -07001239 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001240
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 md= [HW] RAID subsystems devices and level
1242 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 mdacon= [MDA]
1245 Format: <first>,<last>
1246 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001247
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1249 Amount of memory to be used when the kernel is not able
1250 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001251 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 address space collisions. Without memmap= PCI devices
1253 could be placed at addresses belonging to unused RAM.
1254
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001255 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 memory.
1257
Paul Mundt6902aa82008-09-21 17:14:42 +09001258 memchunk=nn[KMG]
1259 [KNL,SH] Allow user to override the default size for
1260 per-device physically contiguous DMA buffers.
1261
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001262 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 E820 memory map, as specified by the user.
1264 Such memmap=exactmap lines can be constructed based on
1265 BIOS output or other requirements. See the memmap=nn@ss
1266 option description.
1267
1268 memmap=nn[KMG]@ss[KMG]
1269 [KNL] Force usage of a specific region of memory
1270 Region of memory to be used, from ss to ss+nn.
1271
1272 memmap=nn[KMG]#ss[KMG]
1273 [KNL,ACPI] Mark specific memory as ACPI data.
1274 Region of memory to be used, from ss to ss+nn.
1275
1276 memmap=nn[KMG]$ss[KMG]
1277 [KNL,ACPI] Mark specific memory as reserved.
1278 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001279 Example: Exclude memory from 0x18690000-0x1869ffff
1280 memmap=64K$0x18690000
1281 or
1282 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001284 memory_corruption_check=0/1 [X86]
1285 Some BIOSes seem to corrupt the first 64k of
1286 memory when doing things like suspend/resume.
1287 Setting this option will scan the memory
1288 looking for corruption. Enabling this will
1289 both detect corruption and prevent the kernel
1290 from using the memory being corrupted.
1291 However, its intended as a diagnostic tool; if
1292 repeatable BIOS-originated corruption always
1293 affects the same memory, you can use memmap=
1294 to prevent the kernel from using that memory.
1295
1296 memory_corruption_check_size=size [X86]
1297 By default it checks for corruption in the low
1298 64k, making this memory unavailable for normal
1299 use. Use this parameter to scan for
1300 corruption in more or less memory.
1301
1302 memory_corruption_check_period=seconds [X86]
1303 By default it checks for corruption every 60
1304 seconds. Use this parameter to check at some
1305 other rate. 0 disables periodic checking.
1306
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001307 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001308 Format: <integer>
1309 range: 0,4 : pattern number
1310 default : 0 <disable>
1311
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 meye.*= [HW] Set MotionEye Camera parameters
1313 See Documentation/video4linux/meye.txt.
1314
Andres Salomon8f368812007-10-12 23:04:06 +02001315 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1316 Multi-Function General Purpose Timers on AMD Geode
1317 platforms.
1318
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001319 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1320 the BIOS has incorrectly applied a workaround. TinyBIOS
1321 version 0.98 is known to be affected, 0.99 fixes the
1322 problem by letting the user disable the workaround.
1323
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 mga= [HW,DRM]
1325
Mel Gorman6b74ab92008-07-23 21:26:49 -07001326 mminit_loglevel=
1327 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1328 parameter allows control of the logging verbosity for
1329 the additional memory initialisation checks. A value
1330 of 0 disables mminit logging and a level of 4 will
1331 log everything. Information is printed at KERN_DEBUG
1332 so loglevel=8 may also need to be specified.
1333
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 mousedev.tap_time=
1335 [MOUSE] Maximum time between finger touching and
1336 leaving touchpad surface for touch to be considered
1337 a tap and be reported as a left button click (for
1338 touchpads working in absolute mode only).
1339 Format: <msecs>
1340 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1341 reporting absolute coordinates, such as tablets
1342 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1343 reporting absolute coordinates, such as tablets
1344
1345 mpu401= [HW,OSS]
1346 Format: <io>,<irq>
1347
1348 MTD_Partition= [MTD]
1349 Format: <name>,<region-number>,<size>,<offset>
1350
Randy Dunlapa9913042005-10-23 12:57:11 -07001351 MTD_Region= [MTD] Format:
1352 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
1354 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001355 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356
Ben Dooks9db829f2008-07-03 11:24:29 +01001357 mtdset= [ARM]
1358 ARM/S3C2412 JIVE boot control
1359
1360 See arch/arm/mach-s3c2412/mach-jive.c
1361
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001363 [HW] Make the MicroTouch USB driver use raw coordinates
1364 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
1366 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1367
1368 NCR_D700= [HW,SCSI]
1369 See header of drivers/scsi/NCR_D700.c.
1370
1371 ncr5380= [HW,SCSI]
1372
1373 ncr53c400= [HW,SCSI]
1374
1375 ncr53c400a= [HW,SCSI]
1376
1377 ncr53c406a= [HW,SCSI]
1378
1379 ncr53c8xx= [HW,SCSI]
1380
1381 netdev= [NET] Network devices parameters
1382 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1383 Note that mem_start is often overloaded to mean
1384 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001385 This usage is only documented in each driver source
1386 file if at all.
1387
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001388 nf_conntrack.acct=
1389 [NETFILTER] Enable connection tracking flow accounting
1390 0 to disable accounting
1391 1 to enable accounting
1392 Default value depends on CONFIG_NF_CT_ACCT that is
1393 going to be removed in 2.6.29.
1394
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001396 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397
1398 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001399 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400
Trond Myklebusta72b4422006-01-03 09:55:41 +01001401 nfs.callback_tcpport=
1402 [NFS] set the TCP port on which the NFSv4 callback
1403 channel should listen.
1404
Trond Myklebust58df0952006-01-03 09:55:57 +01001405 nfs.idmap_cache_timeout=
1406 [NFS] set the maximum lifetime for idmapper cache
1407 entries.
1408
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001409 nfs.enable_ino64=
1410 [NFS] enable 64-bit inode numbers.
1411 If zero, the NFS client will fake up a 32-bit inode
1412 number for the readdir() and stat() syscalls instead
1413 of returning the full 64-bit number.
1414 The default is to return 64-bit inode numbers.
1415
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001416 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1417 when a NMI is triggered.
1418 Format: [state][,regs][,debounce][,die]
1419
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001420 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001422 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 emulation library even if a 387 maths coprocessor
1424 is present.
1425
Christoph Lameterc1aee212007-05-31 00:40:47 -07001426 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1427 caches in the slab allocator. Saves per-node memory,
1428 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001429
Randy Dunlapa9913042005-10-23 12:57:11 -07001430 noalign [KNL,ARM]
1431
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432 noapic [SMP,APIC] Tells the kernel to not make use of any
1433 IOAPICs that may be present in the system.
1434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 nobats [PPC] Do not use BATs for mapping kernel lowmem
1436 on "Classic" PPC cores.
1437
1438 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001439
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001440 nodelayacct [KNL] Disable per-task delay accounting
1441
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1443
Paul Mundt6902aa82008-09-21 17:14:42 +09001444 nodsp [SH] Disable hardware DSP at boot time.
1445
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001446 noefi [X86-32,X86-64] Disable EFI runtime services support.
1447
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 noexec [IA-64]
1449
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001450 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001451 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001453 noexec=off: disable non-executable mappings
1454
1455 noexec32 [X86-64]
1456 This affects only 32-bit executables.
1457 noexec32=on: enable non-executable mappings (default)
1458 read doesn't imply executable mappings
1459 noexec32=off: disable non-executable mappings
1460 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461
Paul Mundt6902aa82008-09-21 17:14:42 +09001462 nofpu [SH] Disable hardware FPU at boot time.
1463
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001464 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001465 register save and restore. The kernel will only save
1466 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467
Andi Kleen191679f2008-01-30 13:33:21 +01001468 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1469
Paul Mundt6902aa82008-09-21 17:14:42 +09001470 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001471
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001472 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 instruction doesn't work correctly and not to
1474 use it.
1475
1476 nohalt [IA-64] Tells the kernel not to use the power saving
1477 function PAL_HALT_LIGHT when idle. This increases
1478 power-consumption. On the positive side, it reduces
1479 interrupt wake-up latency, which may improve performance
1480 in certain environments such as networked servers or
1481 real-time systems.
1482
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001483 nohz= [KNL] Boottime enable/disable dynamic ticks
1484 Valid arguments: on, off
1485 Default: on
1486
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001487 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 disable unhandled interrupt sources.
1489
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001490 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001491 broken timer IRQ sources.
1492
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 noisapnp [ISAPNP] Disables ISA PnP code.
1494
1495 noinitrd [RAM] Tells the kernel not to load any configured
1496 initial RAM disk.
1497
1498 nointroute [IA-64]
1499
Tony Luck0aa366f2007-07-20 11:22:30 -07001500 nojitter [IA64] Disables jitter checking for ITC timers.
1501
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001502 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001504 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001505
Suresh Siddha6e1cb382008-07-10 11:16:58 -07001506 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1507
Suresh Siddhaaf9d1382008-07-11 13:11:57 -07001508 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1509 default x2apic cluster mode on platforms
1510 supporting x2apic.
1511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 noltlbs [PPC] Do not use large page/tlb entries for kernel
1513 lowmem mapping on PPC40x.
1514
Horms312f1f02006-02-22 09:57:55 +09001515 nomca [IA-64] Disable machine check abort handling
1516
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001517 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001518
Andres Salomon83d73842007-10-12 23:04:06 +02001519 nomfgpt [X86-32] Disable Multi-Function General Purpose
1520 Timer usage (for AMD Geode machines).
1521
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001522 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001523
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001524 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001525 with UP alternatives
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 noresidual [PPC] Don't use residual data on PReP machines.
1528
Randy Dunlapa9913042005-10-23 12:57:11 -07001529 noresume [SWSUSP] Disables resume and restores original swap
1530 space.
1531
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532 no-scroll [VGA] Disables scrollback.
1533 This is required for the Braillex ib80-piezo Braille
1534 reader made by F.H. Papenmeier (Germany).
1535
1536 nosbagart [IA-64]
1537
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001538 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001539
Len Brown61ec7562007-08-16 03:34:22 -04001540 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1541 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542
Dave Jones97842212007-07-15 23:41:05 -07001543 nosoftlockup [KNL] Disable the soft-lockup detector.
1544
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 nosync [HW,M68K] Disables sync negotiation for all devices.
1546
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001547 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548
1549 nousb [USB] Disable the USB subsystem
1550
1551 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001552
Fenghua Yua6c75b862008-03-14 13:57:08 -07001553 nptcg= [IA64] Override max number of concurrent global TLB
1554 purges which is reported from either PAL_VM_SUMMARY or
1555 SAL PALO.
1556
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001557 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1558 one of ['zone', 'node', 'default'] can be specified
1559 This can be set from sysctl after boot.
1560 See Documentation/sysctl/vm.txt for details.
1561
Dave Jonesa61c2d72006-01-07 23:18:19 +00001562 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1563
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001564 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1565 Rather than timing out after 20 ms if an EC
1566 command is not properly ACKed, override the length
1567 of the timeout. We have interrupts disabled while
1568 waiting for the ACK, so if this is set too high
1569 interrupts *may* be lost!
1570
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 opl3= [HW,OSS]
1572 Format: <io>
1573
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 oprofile.timer= [HW]
1575 Use timer interrupt instead of performance counters
1576
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 osst= [HW,SCSI] SCSI Tape Driver
1578 Format: <buffer_size>,<write_threshold>
1579 See also Documentation/scsi/st.txt.
1580
1581 panic= [KNL] Kernel behaviour on panic
1582 Format: <timeout>
1583
1584 parkbd.port= [HW] Parallel port number the keyboard adapter is
1585 connected to, default is 0.
1586 Format: <parport#>
1587 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1588 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001589 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590
Randy Dunlapa9913042005-10-23 12:57:11 -07001591 parport= [HW,PPT] Specify parallel ports. 0 disables.
1592 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1593 Use 'auto' to force the driver to use any
1594 IRQ/DMA settings detected (the default is to
1595 ignore detected IRQ/DMA settings because of
1596 possible conflicts). You can specify the base
1597 address, IRQ, and DMA settings; IRQ and DMA
1598 should be numbers, or 'auto' (for using detected
1599 settings on that particular port), or 'nofifo'
1600 (to avoid using a FIFO even if it is detected).
1601 Parallel ports are assigned in the order they
1602 are specified on the command line, starting
1603 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
Randy Dunlapa9913042005-10-23 12:57:11 -07001605 parport_init_mode= [HW,PPT]
1606 Configure VIA parallel port to operate in
1607 a specific mode. This is necessary on Pegasos
1608 computer where firmware has no options for setting
1609 up parallel port mode and sets it to spp.
1610 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 Format: [spp|ps2|epp|ecp|ecpepp]
1612
Randy Dunlapa9913042005-10-23 12:57:11 -07001613 pas2= [HW,OSS] Format:
1614 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1615
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 pas16= [HW,SCSI]
1617 See header of drivers/scsi/pas16.c.
1618
Andrew Mortondd287792006-03-23 03:00:57 -08001619 pause_on_oops=
1620 Halt all CPUs after the first oops has been printed for
1621 the specified number of seconds. This is to be used if
1622 your oopses keep scrolling off the screen.
1623
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 pcbit= [HW,ISDN]
1625
1626 pcd. [PARIDE]
1627 See header of drivers/block/paride/pcd.c.
1628 See also Documentation/paride.txt.
1629
Randy Dunlapa9913042005-10-23 12:57:11 -07001630 pci=option[,option...] [PCI] various PCI subsystem options:
Andi Kleenc0115602008-08-22 09:53:39 +02001631 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001632 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001633 the hardware directly. Use this if your machine
1634 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001635 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001636 hardware access methods are allowed. Use this
1637 if you experience crashes upon bootup and you
1638 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001639 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001640 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001641 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001642 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001643 noaer [PCIE] If the PCIEAER kernel config parameter is
1644 enabled, this kernel boot option can be used to
1645 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001646 nodomains [PCI] Disable support for multiple PCI
1647 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001648 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001649 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001650 nomsi [MSI] If the PCI_MSI kernel config parameter is
1651 enabled, this kernel boot option can be used to
1652 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001653 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001654 routing table. These calls are known to be buggy
1655 on several machines and they hang the machine
1656 when used, but on other computers it's the only
1657 way to get the interrupt routing table. Try
1658 this option if the kernel is unable to allocate
1659 IRQs or discover secondary PCI buses on your
1660 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001661 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001662 Use with caution as certain devices share
1663 address decoders between ROMs and other
1664 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001665 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001666 expansion ROMs that do not already have
1667 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001668 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001669 assigned automatically to PCI devices. You can
1670 make the kernel exclude IRQs of your ISA cards
1671 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001672 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001673 of the PIRQ table (normally generated
1674 by the BIOS) if it is outside the
1675 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001676 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001677 useful if the kernel is unable to find your
1678 secondary buses and you want to tell it
1679 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001680 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001681 numbers ourselves, overriding
1682 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001683 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001684 in the BIOS $PIR table. This is needed on
1685 some systems with broken BIOSes, notably
1686 some HP Pavilion N5400 and Omnibook XE3
1687 notebooks. This will have no effect if ACPI
1688 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001689 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001690 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001691 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001692 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001693 routeirq Do IRQ routing for all PCI devices.
1694 This is normally done in pci_enable_device(),
1695 so this option is a temporary workaround
1696 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001697 skip_isa_align [X86] do not align io start addr, so can
1698 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001699 firmware [ARM] Do not re-enumerate the bus but instead
1700 just use the configuration from the
1701 bootloader. This is currently used on
1702 IXP2000 systems where the bus has to be
1703 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001704 noearly [X86] Don't do any early type 1 scanning.
1705 This might help on some broken boards which
1706 machine check when some devices' config space
1707 is read. But various workarounds are disabled
1708 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001709 bfsort Sort PCI devices into breadth-first order.
1710 This sorting is done to get a device
1711 order compatible with older (<= 2.4) kernels.
1712 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001713 cbiosize=nn[KMG] The fixed amount of bus space which is
1714 reserved for the CardBus bridge's IO window.
1715 The default value is 256 bytes.
1716 cbmemsize=nn[KMG] The fixed amount of bus space which is
1717 reserved for the CardBus bridge's memory
1718 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001719
Chuck Ebberte5665a42008-09-24 20:40:34 -04001720 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1721 Management.
1722 off Disable ASPM.
1723 force Enable ASPM even on devices that claim not to support it.
1724 WARNING: Forcing ASPM on may cause system lockups.
1725
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 pcmv= [HW,PCMCIA] BadgePAD 4
1727
1728 pd. [PARIDE]
1729 See Documentation/paride.txt.
1730
1731 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1732 boot time.
1733 Format: { 0 | 1 }
1734 See arch/parisc/kernel/pdc_chassis.c
1735
1736 pf. [PARIDE]
1737 See Documentation/paride.txt.
1738
1739 pg. [PARIDE]
1740 See Documentation/paride.txt.
1741
1742 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001743 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744
1745 plip= [PPT,NET] Parallel port network link
1746 Format: { parport<nr> | timid | 0 }
1747 See also Documentation/parport.txt.
1748
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001749 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1750 Override pmtimer IOPort with a hex value.
1751 e.g. pmtmr=0x508
1752
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001753 pnp.debug [PNP]
1754 Enable PNP debug messages. This depends on the
1755 CONFIG_PNP_DEBUG_MESSAGES option.
1756
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 pnpacpi= [ACPI]
1758 { off }
1759
1760 pnpbios= [ISAPNP]
1761 { on | off | curr | res | no-curr | no-res }
1762
1763 pnp_reserve_irq=
1764 [ISAPNP] Exclude IRQs for the autoconfiguration
1765
1766 pnp_reserve_dma=
1767 [ISAPNP] Exclude DMAs for the autoconfiguration
1768
1769 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001770 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771
1772 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001773 [ISAPNP] Exclude memory regions for the
1774 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775 Ranges are in pairs (memory base and size).
1776
Jason Baron346e15b2008-08-12 16:46:19 -04001777 dynamic_printk
1778 Enables pr_debug()/dev_dbg() calls if
1779 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1780 be switched on/off via <debugfs>/dynamic_printk/modules
1781
Ingo Molnar45807a12007-07-15 23:40:10 -07001782 print-fatal-signals=
1783 [KNL] debug: print fatal signals
1784 print-fatal-signals=1: print segfault info to
1785 the kernel console.
1786 default: off.
1787
Randy Dunlape84845c2007-07-15 23:40:25 -07001788 printk.time= Show timing data prefixed to each printk message line
1789 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1790
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001792 Format: [schedule,]<number>
1793 Param: "schedule" - profile schedule points.
1794 Param: <number> - step/bucket size as a power of 2 for
1795 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001796 Param: "sleep" - profile D-state sleeping (millisecs).
1797 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001798 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799
Randy Dunlapa9913042005-10-23 12:57:11 -07001800 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801 Limit processor to maximum C-state
1802 max_cstate=9 overrides any DMI blacklist limit.
1803
Len Brown41c0d862005-12-28 12:43:51 -05001804 processor.nocst [HW,ACPI]
1805 Ignore the _CST method to determine C-states,
1806 instead using the legacy FADT method
1807
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1809 before loading.
1810 See Documentation/ramdisk.txt.
1811
Randy Dunlapa9913042005-10-23 12:57:11 -07001812 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1813 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1815 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001816 psmouse.resetafter= [HW,MOUSE]
1817 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818 (0 = never).
1819 psmouse.resolution=
1820 [HW,MOUSE] Set desired mouse resolution, in dpi.
1821 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001822 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 0 = disabled, 1 = enabled (default).
1824
1825 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001826 Format:
1827 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828
1829 pt. [PARIDE]
1830 See Documentation/paride.txt.
1831
Kay Sieversdc8c8582007-08-15 12:25:38 +02001832 pty.legacy_count=
1833 [KNL] Number of legacy pty's. Overwrites compiled-in
1834 default number.
1835
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001836 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001837
Linus Torvalds1da177e2005-04-16 15:20:36 -07001838 r128= [HW,DRM]
1839
1840 raid= [HW,RAID]
1841 See Documentation/md.txt.
1842
Randy Dunlapa9913042005-10-23 12:57:11 -07001843 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001845
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 See Documentation/ramdisk.txt.
1848
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001849 rcupdate.blimit= [KNL,BOOT]
1850 Set maximum number of finished RCU callbacks to process
1851 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001852
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001853 rcupdate.qhimark= [KNL,BOOT]
1854 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001855 RCU callbacks over which batch limiting is disabled.
1856
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001857 rcupdate.qlowmark= [KNL,BOOT]
1858 Set threshold of queued RCU callbacks below which
1859 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001860
Olof Johanssonffdfc402005-09-06 15:17:19 -07001861 rdinit= [KNL]
1862 Format: <full_path>
1863 Run specified binary instead of /init from the ramdisk,
1864 used for early userspace startup. See initrd.
1865
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001866 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001868 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869
Paul Jackson46b6d942008-07-04 10:00:09 -07001870 relax_domain_level=
1871 [KNL, SMP] Set scheduler's default relax_domain_level.
1872 See Documentation/cpusets.txt.
1873
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1875
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001876 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001877 Format: nn[KMG]
1878 Reserves a hole at the top of the kernel virtual
1879 address space.
1880
Vivek Goyal7e962872006-09-27 01:50:44 -07001881 reset_devices [KNL] Force drivers to reset the underlying device
1882 during initialization.
1883
Randy Dunlapa9913042005-10-23 12:57:11 -07001884 resume= [SWSUSP]
1885 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001887 resume_offset= [SWSUSP]
1888 Specify the offset from the beginning of the partition
1889 given by "resume=" at which the swap header is located,
1890 in <PAGE_SIZE> units (needed only for swap files).
1891 See Documentation/power/swsusp-and-swap-files.txt
1892
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001893 retain_initrd [RAM] Keep initrd memory after extraction
1894
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895 rhash_entries= [KNL,NET]
1896 Set number of hash buckets for route cache
1897
1898 riscom8= [HW,SERIAL]
1899 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1900
1901 ro [KNL] Mount root device read-only on boot
1902
1903 root= [KNL] Root filesystem
1904
1905 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1906 mount the root filesystem
1907
1908 rootflags= [KNL] Set root filesystem mount option string
1909
1910 rootfstype= [KNL] Set root filesystem type
1911
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001912 rootwait [KNL] Wait (indefinitely) for root device to show up.
1913 Useful for devices that are detected asynchronously
1914 (e.g. USB and MMC devices).
1915
James Morris20510f22007-10-16 23:31:32 -07001916 root_plug.vendor_id=
1917 [ROOTPLUG] Override the default vendor ID
1918
1919 root_plug.product_id=
1920 [ROOTPLUG] Override the default product ID
1921
1922 root_plug.debug=
1923 [ROOTPLUG] Enable debugging output
1924
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 rw [KNL] Mount root device read-write on boot
1926
1927 S [KNL] Run init in single mode
1928
1929 sa1100ir [NET]
1930 See drivers/net/irda/sa1100_ir.c.
1931
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001933
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1935 Format: <io>[,<timeout>[,<isapnp>]]
1936
1937 scsi_debug_*= [SCSI]
1938 See drivers/scsi/scsi_debug.c.
1939
1940 scsi_default_dev_flags=
1941 [SCSI] SCSI default device flags
1942 Format: <integer>
1943
1944 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1945 Format: <vendor>:<model>:<flags>
1946 (flags are integer value)
1947
Randy Dunlap6af66322007-11-14 16:52:25 -08001948 scsi_logging_level= [SCSI] a bit mask of logging levels
1949 See drivers/scsi/scsi_logging.h for bits. Also
1950 settable via sysctl at dev.scsi.logging_level
1951 (/proc/sys/dev/scsi/logging_level).
1952 There is also a nice 'scsi_logging_level' script in the
1953 S390-tools package, available for download at
1954 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001956 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1957 discovered. async scans them in kernel threads,
1958 allowing boot to proceed. none ignores them, expecting
1959 user space to do the scan.
1960
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 selinux [SELINUX] Disable or enable SELinux at boot time.
1962 Format: { "0" | "1" }
1963 See security/selinux/Kconfig help text.
1964 0 -- disable.
1965 1 -- enable.
1966 Default value is set via kernel config option.
1967 If enabled at boot time, /selinux/disable can be used
1968 later to disable prior to initial policy load.
1969
James Morris4e5ab4c2006-06-09 00:33:33 -07001970 selinux_compat_net =
1971 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001972 Format: { "0" | "1" }
1973 0 -- use new secmark-based packet controls
1974 1 -- use legacy packet controls
1975 Default value is 0 (preferred).
1976 Value can be changed at runtime via
1977 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001978
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001979 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 shapers= [NET]
1982 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001983
Yinghai Lub05f78f2008-08-22 01:32:50 -07001984 show_msr= [x86] show boot-time MSR settings
1985 Format: { <integer> }
1986 Show boot-time (BIOS-initialized) MSR settings.
1987 The parameter means the number of CPUs to show,
1988 for example 1 means boot CPU only.
1989
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 sim710= [SCSI,HW]
1991 See header of drivers/scsi/sim710.c.
1992
1993 simeth= [IA-64]
1994 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001995
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996 slram= [HW,MTD]
1997
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001998 slub_debug[=options[,slabs]] [MM, SLUB]
1999 Enabling slub_debug allows one to determine the
2000 culprit if slab objects become corrupted. Enabling
2001 slub_debug can create guard zones around objects and
2002 may poison objects when not in use. Also tracks the
2003 last alloc / free. For more information see
2004 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002005
2006 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002007 Determines the maximum allowed order for slabs.
2008 A high setting may cause OOMs due to memory
2009 fragmentation. For more information see
2010 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002011
2012 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002013 The minimum number of objects per slab. SLUB will
2014 increase the slab order up to slub_max_order to
2015 generate a sufficiently large slab able to contain
2016 the number of objects indicated. The higher the number
2017 of objects the smaller the overhead of tracking slabs
2018 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002019 For more information see Documentation/vm/slub.txt.
2020
2021 slub_min_order= [MM, SLUB]
2022 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002023 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002024 For more information see Documentation/vm/slub.txt.
2025
2026 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002027 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002028 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002029 allocs to different slabs. Debug options disable
2030 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002031 For more information see Documentation/vm/slub.txt.
2032
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 smart2= [HW]
2034 Format: <io1>[,<io2>[,...,<io8>]]
2035
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002036 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002037 attempt to substitute SMP alternatives once at boot.
2038
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002039 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2040 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2041 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2042 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2043 smsc-ircc2.ircc_irq= [HW] IRQ line
2044 smsc-ircc2.ircc_dma= [HW] DMA channel
2045 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2046 0: Toshiba Satellite 1800 (GP data pin select)
2047 1: Fast pin select (default)
2048 2: ATC IRMode
2049
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050 snd-ad1816a= [HW,ALSA]
2051
2052 snd-ad1848= [HW,ALSA]
2053
2054 snd-ali5451= [HW,ALSA]
2055
2056 snd-als100= [HW,ALSA]
2057
2058 snd-als4000= [HW,ALSA]
2059
2060 snd-azt2320= [HW,ALSA]
2061
2062 snd-cmi8330= [HW,ALSA]
2063
2064 snd-cmipci= [HW,ALSA]
2065
2066 snd-cs4231= [HW,ALSA]
2067
2068 snd-cs4232= [HW,ALSA]
2069
2070 snd-cs4236= [HW,ALSA]
2071
2072 snd-cs4281= [HW,ALSA]
2073
2074 snd-cs46xx= [HW,ALSA]
2075
2076 snd-dt019x= [HW,ALSA]
2077
2078 snd-dummy= [HW,ALSA]
2079
2080 snd-emu10k1= [HW,ALSA]
2081
2082 snd-ens1370= [HW,ALSA]
2083
2084 snd-ens1371= [HW,ALSA]
2085
2086 snd-es968= [HW,ALSA]
2087
2088 snd-es1688= [HW,ALSA]
2089
2090 snd-es18xx= [HW,ALSA]
2091
2092 snd-es1938= [HW,ALSA]
2093
2094 snd-es1968= [HW,ALSA]
2095
2096 snd-fm801= [HW,ALSA]
2097
2098 snd-gusclassic= [HW,ALSA]
2099
2100 snd-gusextreme= [HW,ALSA]
2101
2102 snd-gusmax= [HW,ALSA]
2103
2104 snd-hdsp= [HW,ALSA]
2105
2106 snd-ice1712= [HW,ALSA]
2107
2108 snd-intel8x0= [HW,ALSA]
2109
2110 snd-interwave= [HW,ALSA]
2111
2112 snd-interwave-stb=
2113 [HW,ALSA]
2114
2115 snd-korg1212= [HW,ALSA]
2116
2117 snd-maestro3= [HW,ALSA]
2118
2119 snd-mpu401= [HW,ALSA]
2120
2121 snd-mtpav= [HW,ALSA]
2122
2123 snd-nm256= [HW,ALSA]
2124
2125 snd-opl3sa2= [HW,ALSA]
2126
2127 snd-opti92x-ad1848=
2128 [HW,ALSA]
2129
2130 snd-opti92x-cs4231=
2131 [HW,ALSA]
2132
2133 snd-opti93x= [HW,ALSA]
2134
2135 snd-pmac= [HW,ALSA]
2136
2137 snd-rme32= [HW,ALSA]
2138
2139 snd-rme96= [HW,ALSA]
2140
2141 snd-rme9652= [HW,ALSA]
2142
2143 snd-sb8= [HW,ALSA]
2144
2145 snd-sb16= [HW,ALSA]
2146
2147 snd-sbawe= [HW,ALSA]
2148
2149 snd-serial= [HW,ALSA]
2150
2151 snd-sgalaxy= [HW,ALSA]
2152
2153 snd-sonicvibes= [HW,ALSA]
2154
2155 snd-sun-amd7930=
2156 [HW,ALSA]
2157
2158 snd-sun-cs4231= [HW,ALSA]
2159
2160 snd-trident= [HW,ALSA]
2161
2162 snd-usb-audio= [HW,ALSA,USB]
2163
2164 snd-via82xx= [HW,ALSA]
2165
2166 snd-virmidi= [HW,ALSA]
2167
2168 snd-wavefront= [HW,ALSA]
2169
2170 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002171
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002172 softlockup_panic=
2173 [KNL] Should the soft-lockup detector generate panics.
2174
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2176 See Documentation/sonypi.txt
2177
2178 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2179 See Documentation/specialix.txt.
2180
2181 spia_io_base= [HW,MTD]
2182 spia_fio_base=
2183 spia_pedr=
2184 spia_peddr=
2185
2186 sscape= [HW,OSS]
2187 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002188
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2190 See Documentation/scsi/st.txt.
2191
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 sti= [PARISC,HW]
2193 Format: <num>
2194 Set the STI (builtin display/keyboard on the HP-PARISC
2195 machines) console (graphic card) which should be used
2196 as the initial boot-console.
2197 See also comment in drivers/video/console/sticore.c.
2198
2199 sti_font= [HW]
2200 See comment in drivers/video/console/sticore.c.
2201
2202 stifb= [HW]
2203 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2204
Greg Banks42a7fc42007-03-06 01:42:23 -08002205 sunrpc.pool_mode=
2206 [NFS]
2207 Control how the NFS server code allocates CPUs to
2208 service thread pools. Depending on how many NICs
2209 you have and where their interrupts are bound, this
2210 option will affect which CPUs will do NFS serving.
2211 Note: this parameter cannot be changed while the
2212 NFS server is running.
2213
2214 auto the server chooses an appropriate mode
2215 automatically using heuristics
2216 global a single global pool contains all CPUs
2217 percpu one pool for each CPU
2218 pernode one pool for each NUMA node (equivalent
2219 to global on non-NUMA machines)
2220
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002222
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223 switches= [HW,M68k]
2224
2225 sym53c416= [HW,SCSI]
2226 See header of drivers/scsi/sym53c416.c.
2227
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002228 sysrq_always_enabled
2229 [KNL]
2230 Ignore sysrq setting - this boot parameter will
2231 neutralize any effect of /proc/sys/kernel/sysrq.
2232 Useful for debugging.
2233
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234 t128= [HW,SCSI]
2235 See header of drivers/scsi/t128.c.
2236
2237 tdfx= [HW,DRM]
2238
David Brownell77437fd2008-07-23 21:28:33 -07002239 test_suspend= [SUSPEND]
2240 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2241 standby suspend) as the system sleep state to briefly
2242 enter during system startup. The system is woken from
2243 this state using a wakeup-capable RTC alarm.
2244
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 thash_entries= [KNL,NET]
2246 Set number of hash buckets for TCP connection
2247
Len Brownf8707ec2007-08-12 00:12:54 -04002248 thermal.act= [HW,ACPI]
2249 -1: disable all active trip points in all thermal zones
2250 <degrees C>: override all lowest active trip points
2251
Len Brownc52a7412007-08-14 15:49:32 -04002252 thermal.crt= [HW,ACPI]
2253 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002254 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002255
Len Brownf5487142007-08-12 00:12:44 -04002256 thermal.nocrt= [HW,ACPI]
2257 Set to disable actions on ACPI thermal zone
2258 critical and hot trip points.
2259
Len Brown72b33ef2007-08-12 00:12:17 -04002260 thermal.off= [HW,ACPI]
2261 1: disable ACPI thermal control
2262
Len Browna70cdc52007-08-12 00:12:35 -04002263 thermal.psv= [HW,ACPI]
2264 -1: disable all passive trip points
2265 <degrees C>: override all passive trip points to this value
2266
Len Brown730ff342007-08-12 00:12:26 -04002267 thermal.tzp= [HW,ACPI]
2268 Specify global default ACPI thermal zone polling rate
2269 <deci-seconds>: poll all this frequency
2270 0: no polling (default)
2271
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 tmscsim= [HW,SCSI]
2273 See comment before function dc390_setup() in
2274 drivers/scsi/tmscsim.c.
2275
2276 tp720= [HW,PS2]
2277
2278 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002279 Format:
2280 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2281
Randy Dunlapa9913042005-10-23 12:57:11 -07002282 turbografx.map[2|3]= [HW,JOY]
2283 TurboGraFX parallel port interface
2284 Format:
2285 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002286 See also Documentation/input/joystick-parport.txt
2287
2288 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2289 See header of drivers/scsi/u14-34f.c.
2290
2291 uart401= [HW,OSS]
2292 Format: <io>,<irq>
2293
2294 uart6850= [HW,OSS]
2295 Format: <io>,<irq>
2296
Alan Stern5f8364b2006-12-05 16:29:55 -05002297 uhci-hcd.ignore_oc=
2298 [USB] Ignore overcurrent events (default N).
2299 Some badly-designed motherboards generate lots of
2300 bogus events, for ports that aren't wired to
2301 anything. Set this parameter to avoid log spamming.
2302 Note that genuine overcurrent events won't be
2303 reported either.
2304
Simon Arlotte3a61b02008-07-19 23:32:54 +01002305 unknown_nmi_panic
2306 [X86-32,X86-64]
2307 Set unknown_nmi_panic=1 early on boot.
2308
Alan Sternb5e795f2007-02-20 15:00:53 -05002309 usbcore.autosuspend=
2310 [USB] The autosuspend time delay (in seconds) used
2311 for newly-detected USB devices (default 2). This
2312 is the time required before an idle device will be
2313 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002314 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002315
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002316 usbcore.usbfs_snoop=
2317 [USB] Set to log all usbfs traffic (default 0 = off).
2318
2319 usbcore.blinkenlights=
2320 [USB] Set to cycle leds on hubs (default 0 = off).
2321
2322 usbcore.old_scheme_first=
2323 [USB] Start with the old device initialization
2324 scheme (default 0 = off).
2325
2326 usbcore.use_both_schemes=
2327 [USB] Try the other device initialization scheme
2328 if the first one fails (default 1 = enabled).
2329
2330 usbcore.initial_descriptor_timeout=
2331 [USB] Specifies timeout for the initial 64-byte
2332 USB_REQ_GET_DESCRIPTOR request in milliseconds
2333 (default 5000 = 5.0 seconds).
2334
Linus Torvalds1da177e2005-04-16 15:20:36 -07002335 usbhid.mousepoll=
2336 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002337
Paul Jackson200001e2008-06-25 05:44:46 -07002338 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2339 kernel's map of available physical RAM.
2340
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002341 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002342 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002343 vdso=1: enable VDSO (default)
2344 vdso=0: disable VDSO mapping
2345
Roland McGrathaf65d642008-01-30 13:30:43 +01002346 vdso32= [X86-32,X86-64]
2347 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2348 vdso32=1: enable 32-bit VDSO (default)
2349 vdso32=0: disable 32-bit VDSO mapping
2350
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002351 vector= [IA-64,SMP]
2352 vector=percpu: enable percpu vector domain
2353
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 video= [FB] Frame buffer configuration
2355 See Documentation/fb/modedb.txt.
2356
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002357 vga= [BOOT,X86-32] Select a particular video mode
Uwe Hermann71cced62008-10-20 09:32:21 -07002358 See Documentation/x86/i386/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002359 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360 Use vga=ask for menu.
2361 This is actually a boot loader parameter; the value is
2362 passed to the kernel using a special protocol.
2363
Randy Dunlapa9913042005-10-23 12:57:11 -07002364 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365 size of <nn>. This can be used to increase the
2366 minimum size (128MB on x86). It can also be used to
2367 decrease the size and leave more room for directly
2368 mapped kernel RAM.
2369
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002370 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2371 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002372
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002373 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2374 Format: <command>
2375
2376 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2377 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002378
Linus Torvalds1da177e2005-04-16 15:20:36 -07002379 waveartist= [HW,OSS]
2380 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002381
Linus Torvalds1da177e2005-04-16 15:20:36 -07002382 wd33c93= [HW,SCSI]
2383 See header of drivers/scsi/wd33c93.c.
2384
2385 wd7000= [HW,SCSI]
2386 See header of drivers/scsi/wd7000.c.
2387
2388 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002389 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390
2391 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2392 xd_geo= See header of drivers/block/xd.c.
2393
2394 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002395 Format:
2396 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002397
Andi Kleena62eaf12006-02-16 23:41:58 +01002398 norandmaps Don't use address space randomization
2399 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2400
Randy Dunlapa9913042005-10-23 12:57:11 -07002401______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002402
2403TODO:
2404
2405 Add documentation for ALSA options.
2406 Add more DRM drivers.