blob: f5fce483930cf933d0eb7928f1a4fa6cfe8ff921 [file] [log] [blame]
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
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050061 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020062 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070063 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070072 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070073 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070076 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070079 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070083 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
93 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070094 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 SELINUX SELinux support is enabled.
96 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090097 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500102 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300103 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500105 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700113 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700116 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119In addition, the following text indicates that the option:
120
121 BUGS= Relates to possible processor bugs on the said processor.
122 KNL Is a kernel start-up parameter.
123 BOOT Is a boot loader parameter.
124
125Parameters denoted with BOOT are actually interpreted by the boot
126loader, and have no meaning to the kernel directly.
127Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500128need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Karsten Weiss55588702007-02-13 13:26:21 +0100130There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700131See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
134a trailing = on the name of any parameter states that that parameter will
135be entered as an environment variable, whereas its absence indicates that
136it will appear as a kernel argument readable via /proc/cmdline by programs
137running once the system is up.
138
jens m. noedler9c4751f2006-09-29 02:00:27 -0700139The number of kernel parameters is not limited, but the length of the
140complete command line (parameters including spaces etc.) is limited to
141a fixed number of characters. This limit depends on the architecture
142and is between 256 and 4096 characters. It is defined in the file
143./include/asm/setup.h as COMMAND_LINE_SIZE.
144
145
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530146 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800147 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800148 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 force -- enable ACPI if default was off
150 off -- disable ACPI if default was on
151 noirq -- do not use ACPI for IRQ routing
152 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700153 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800155 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800156 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Randy Dunlap53471122008-03-12 18:10:51 -0400158 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Len Browna1fdcc02007-03-11 03:26:14 -0400160 acpi_apic_instance= [ACPI, IOAPIC]
161 Format: <int>
162 2: use 2nd APIC table, if available
163 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400164 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400165
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200166 acpi_backlight= [HW,ACPI]
167 acpi_backlight=vendor
168 acpi_backlight=video
169 If set to vendor, prefer vendor specific driver
170 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
171 of the ACPI video.ko driver.
172
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700173 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
174 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700176 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
177 debug output. Bits in debug_layer correspond to a
178 _COMPONENT in an ACPI source file, e.g.,
179 #define _COMPONENT ACPI_PCI_COMPONENT
180 Bits in debug_level correspond to a level in
181 ACPI_DEBUG_PRINT statements, e.g.,
182 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600183 The debug_level mask defaults to "info". See
184 Documentation/acpi/debug.txt for more information about
185 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600187 Enable processor driver info messages:
188 acpi.debug_layer=0x20000000
189 Enable PCI/PCI interrupt routing info messages:
190 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700191 Enable AML "Debug" output, i.e., stores to the Debug
192 object while interpreting AML:
193 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700194 Enable all messages related to ACPI hardware:
195 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200196
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700197 Some values produce so much output that the system is
198 unusable. The "log_buf_len" parameter may be useful
199 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800200
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700201 acpi_display_output= [HW,ACPI]
202 acpi_display_output=vendor
203 acpi_display_output=video
204 See above.
205
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
208 default in APIC mode
209
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
212 default in PIC mode
213
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
216
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 use by PCI
219 Format: <irq>,<irq>...
220
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
222
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
225
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
230
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530231 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
235
Randy Dunlap4af94f32009-04-17 18:30:28 -0700236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
238
239 acpi_serialize [HW,ACPI] force serialization of AML methods
240
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
244
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800247 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700248 See Documentation/power/video.txt for information on
249 s3_bios and s3_mode.
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
258 s4_nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700263
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
267
Luca Tettamanti7e905602009-03-30 00:01:27 +0200268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
283
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
286
Randy Dunlap4af94f32009-04-17 18:30:28 -0700287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 advansys= [HW,SCSI]
291 See header of drivers/scsi/advansys.c.
292
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
295
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700299
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700300 agp= [AGP]
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 aha152x= [HW,SCSI]
307 See Documentation/scsi/aha152x.txt.
308
309 aha1542= [HW,SCSI]
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
311
312 aic7xxx= [HW,SCSI]
313 See Documentation/scsi/aic7xxx.txt.
314
315 aic79xx= [HW,SCSI]
316 See Documentation/scsi/aic79xx.txt.
317
Russell Kingd944d542010-02-20 16:13:29 +0000318 alignment= [KNL,ARM]
319 Allow the default userspace alignment fault handler
320 behaviour to be specified. Bit 0 enables warnings,
321 bit 1 enables fixups, and bit 2 sends a segfault.
322
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200323 amd_iommu= [HW,X86-84]
324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
329 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200330 off - do not initialize any AMD IOMMU found in
331 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900332
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
335 Format: <a>,<b>
336 See also Documentation/kernel/input/joystick.txt
337
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
342
Randy Dunlapa9913042005-10-23 12:57:11 -0700343 apc= [HW,SPARC]
344 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 Format: noidle
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
349
Randy Dunlapca1eda22009-05-06 16:02:58 -0700350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700351 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700355
Brian Haleyb0f83b22010-02-04 13:36:50 -0800356 autoconf= [IPV6]
357 See Documentation/networking/ipv6.txt.
358
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700369 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
373
374 ataflop= [HW,M68k]
375
376 atarimouse= [HW,MOUSE] Atari Mouse
377
378 atascsi= [HW,SCSI] Atari SCSI
379
380 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
381 EzKey and similar keyboards
382
383 atkbd.reset= [HW] Reset keyboard during initialization
384
Randy Dunlapa9913042005-10-23 12:57:11 -0700385 atkbd.set= [HW] Select keyboard code set
386 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387
388 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 keyboards
390
391 atkbd.softraw= [HW] Choose between synthetic and real raw mode
392 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700393
394 atkbd.softrepeat= [HW]
395 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
397 autotest [IA64]
398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 baycom_epp= [HW,AX25]
400 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
403 Format: <io>,<mode>
404 See header of drivers/net/hamradio/baycom_par.c.
405
Randy Dunlapa9913042005-10-23 12:57:11 -0700406 baycom_ser_fdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 Format: <io>,<irq>,<mode>[,<baud>]
409 See header of drivers/net/hamradio/baycom_ser_fdx.c.
410
Randy Dunlapa9913042005-10-23 12:57:11 -0700411 baycom_ser_hdx= [HW,AX25]
412 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 Format: <io>,<irq>,<mode>
414 See header of drivers/net/hamradio/baycom_ser_hdx.c.
415
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700416 boot_delay= Milliseconds to delay each printk during boot.
417 Values larger than 10 seconds (10000) are changed to
418 no delay (0).
419 Format: integer
420
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700421 bootmem_debug [KNL] Enable bootmem allocator debug messages.
422
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700424 bttv.radio= Most important insmod options are available as
425 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
428
429 BusLogic= [HW,SCSI]
430 See drivers/scsi/BusLogic.c, comment before function
431 BusLogic_ParseDriverOptions().
432
433 c101= [NET] Moxa C101 synchronous serial card
434
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700435 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 Sometimes CPU hardware bugs make them report the cache
437 size incorrectly. The kernel will attempt work arounds
438 to fix known problems, but for some CPUs it is not
439 possible to determine what the correct size should be.
440 This option provides an override for these situations.
441
James Morris20510f22007-10-16 23:31:32 -0700442 capability.disable=
443 [SECURITY] Disable capabilities. This would normally
444 be used only if an alternative security model is to be
445 configured. Potentially dangerous and should only be
446 used if you are entirely sure of the consequences.
447
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100448 ccw_timeout_log [S390]
449 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450
Paul Menage8bab8dd2008-04-04 14:29:57 -0700451 cgroup_disable= [KNL] Disable a particular controller
452 Format: {name of the controller(s) to disable}
453 {Currently supported controllers - "memory"}
454
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 checkreqprot [SELINUX] Set initial checkreqprot flag value.
456 Format: { "0" | "1" }
457 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700458 0 -- check protection applied by kernel (includes
459 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 1 -- check protection requested by application.
461 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700462 Value can be changed at runtime via
463 /selinux/checkreqprot.
464
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100465 cio_ignore= [S390]
466 See Documentation/s390/CommonIO for details.
467
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700468 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700469 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200470 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700471 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200472 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 Format: { pit | tsc | cyclone | pmtmr }
474
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700475 clocksource= [GENERIC_TIME] Override the default clocksource
476 Format: <string>
477 Override the default clocksource and use the clocksource
478 with the name specified.
479 Some clocksource names to choose from, depending on
480 the platform:
481 [all] jiffies (this is the base, fallback clocksource)
482 [ACPI] acpi_pm
483 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
484 pxa_timer,timer3,32k_counter,timer0_1
485 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700486 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700487 scx200_hrt on Geode; cyclone on IBM x440
488 [MIPS] MIPS
489 [PARISC] cr16
490 [S390] tod
491 [SH] SuperH
492 [SPARC64] tick
493 [X86-64] hpet,tsc
494
Andi Kleenac72e782008-01-30 13:33:21 +0100495 clearcpuid=BITNUM [X86]
496 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800497 arch/x86/include/asm/cpufeature.h for the valid bit
498 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100499 stable over kernel options, but the vendor specific
500 ones should be.
501 Also note that user programs calling CPUID directly
502 or using the feature without checking anything
503 will still see it. This just prevents it from
504 being used by the kernel or shown in /proc/cpuinfo.
505 Also note the kernel might malfunction if you disable
506 some critical bits.
507
Robert Jennings14f966e2009-04-15 05:55:32 +0000508 cmo_free_hint= [PPC] Format: { yes | no }
509 Specify whether pages are marked as being inactive
510 when they are freed. This is used in CMO environments
511 to determine OS memory pressure for page stealing by
512 a hypervisor.
513 Default: yes
514
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530515 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100516 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100517 Range: 0 - 8192
518 Default: 64
519
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700521 Format:
522 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
524 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 Format: <io>[,<irq>]
526
Randy Dunlapa9913042005-10-23 12:57:11 -0700527 com90xx= [HW,NET]
528 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 Format: <io>[,<irq>[,<memstart>]]
530
531 condev= [HW,S390] console device
532 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700533
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 console= [KNL] Output console device and options.
535
536 tty<n> Use the virtual console device <n>.
537
538 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800539 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800541 the form "bbbbpnf", where "bbbb" is the baud rate,
542 "p" is parity ("n", "o", or "e"), "n" is number of
543 bits, and "f" is flow control ("r" for RTS or
544 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800546 See Documentation/serial-console.txt for more
547 information. See
548 Documentation/networking/netconsole.txt for an
549 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700551 uart[8250],io,<addr>[,options]
552 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 Start an early, polled-mode console on the 8250/16550
554 UART at the specified I/O port or MMIO address,
555 switching to the matching ttyS device later. The
556 options are the same as for ttyS, above.
557
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700558 If the device connected to the port is not a TTY but a braille
559 device, prepend "brl," before the device type, for instance
560 console=brl,ttyS0
561 For now, only VisioBraille is supported.
562
Daniel Mackf324edc2009-06-16 15:33:52 -0700563 consoleblank= [KNL] The console blank (screen saver) timeout in
564 seconds. Defaults to 10*60 = 10mins. A value of 0
565 disables the blank timer.
566
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800567 coredump_filter=
568 [KNL] Change the default value for
569 /proc/<pid>/coredump_filter.
570 See also Documentation/filesystems/proc.txt.
571
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700573 Format:
574 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700576 crashkernel=nn[KMG]@ss[KMG]
577 [KNL] Reserve a chunk of physical memory to
578 hold a kernel to switch to with kexec on panic.
579
Bernhard Wallefb391592007-10-18 23:41:02 -0700580 crashkernel=range1:size1[,range2:size2,...][@offset]
581 [KNL] Same as above, but depends on the memory
582 in the running system. The syntax of range is
583 start-[end] where start and end are both
584 a memory unit (amount[KMG]). See also
585 Documentation/kdump/kdump.txt for a example.
586
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 cs89x0_dma= [HW,NET]
588 Format: <dma>
589
590 cs89x0_media= [HW,NET]
591 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700592
Randy Dunlapa9913042005-10-23 12:57:11 -0700593 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 See header of drivers/s390/block/dasd_devmap.c.
595
596 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
597 (one device per port)
598 Format: <port#>,<type>
599 See also Documentation/input/joystick-parport.txt
600
601 debug [KNL] Enable kernel debugging (events log level).
602
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700603 debug_locks_verbose=
604 [KNL] verbose self-tests
605 Format=<0|1>
606 Print debugging info while doing the locking API
607 self-tests.
608 We default to 0 (no extra messages), setting it to
609 1 will print _a lot_ more information - normally
610 only useful to kernel developers.
611
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700612 debug_objects [KNL] Enable object debugging
613
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500614 no_debug_objects
615 [KNL] Disable object debugging
616
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200617 debugpat [X86] Enable PAT debugging
618
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200619 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 Format: <area>[,<node>]
621 See also Documentation/networking/decnet.txt.
622
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700623 default_hugepagesz=
624 [same as hugepagesz=] The size of the default
625 HugeTLB page size. This is the size represented by
626 the legacy /proc/ hugepages APIs, used for SHM, and
627 default size when mounting hugetlbfs filesystems.
628 Defaults to the default architecture's huge page size
629 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700630
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 dhash_entries= [KNL]
632 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700633
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 digi= [HW,SERIAL]
635 IO parameters + enable/disable command.
636
637 digiepca= [HW,SERIAL]
638 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000639 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640
Brian Haleyb0f83b22010-02-04 13:36:50 -0800641 disable= [IPV6]
642 See Documentation/networking/ipv6.txt.
643
644 disable_ipv6= [IPV6]
645 See Documentation/networking/ipv6.txt.
646
Yinghai Lu95ffa242008-04-29 03:52:33 -0700647 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700648 The kernel tries to adjust MTRR layout from continuous
649 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700650 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700651
Yinghai Lu093af8d2008-01-30 13:33:32 +0100652 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100653 By default the kernel will trim any uncacheable
654 memory out of your available memory pool based on
655 MTRR settings. This parameter disables that behavior,
656 possibly causing your machine to run very slowly.
657
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530658 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700659 Disable PIN 1 of APIC timer
660 Can be useful to work around chipset bugs.
661
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 dmasound= [HW,OSS] Sound subsystem buffers
663
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700664 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
665 this option disables the debugging code at boot.
666
667 dma_debug_entries=<number>
668 This option allows to tune the number of preallocated
669 entries for DMA-API debugging code. One entry is
670 required per DMA-API allocation. Use this if the
671 DMA-API debugging code disables itself because the
672 architectural default is too low.
673
Joerg Roedel1745de52009-05-22 21:49:51 +0200674 dma_debug_driver=<driver_name>
675 With this option the DMA-API debugging driver
676 filter feature can be enabled at boot time. Just
677 pass the driver to filter for as the parameter.
678 The filter can be disabled or changed to another
679 driver later using sysfs.
680
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 dscc4.setup= [NET]
682
683 dtc3181e= [HW,SCSI]
684
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700685 dynamic_printk Enables pr_debug()/dev_dbg() calls if
686 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
687 These can also be switched on/off via
688 <debugfs>/dynamic_printk/modules
689
690 earlycon= [KNL] Output early console device and options.
691 uart[8250],io,<addr>[,options]
692 uart[8250],mmio,<addr>[,options]
693 Start an early, polled-mode console on the 8250/16550
694 UART at the specified I/O port or MMIO address.
695 The options are the same as for ttyS, above.
696
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530697 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 earlyprintk=vga
699 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500700 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500701 earlyprintk=dbgp[debugController#]
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
Jason Wessel97311912010-05-20 21:04:30 -0500716 ekgdboc= [X86,KGDB] Allow early kernel console debugging
717 ekgdboc=kbd
718
719 This is desgined to be used in conjunction with
720 the boot argument: earlyprintk=vga
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 eata= [HW,SCSI]
723
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700725 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 eisa_irq_edge= [PARISC,HW]
728 See header of drivers/parisc/eisa.c.
729
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700730 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700732 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
734 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800735 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700736 See Documentation/block/as-iosched.txt and
737 Documentation/block/deadline-iosched.txt for details.
738
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530739 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700740 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800741 image elf header. Generally kexec loader will
742 pass this option to capture kernel.
743 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700745 enable_mtrr_cleanup [X86]
746 The kernel tries to adjust MTRR layout from continuous
747 to discrete, to make X server driver able to add WB
748 entry later. This parameter enables that.
749
Randy Dunlapca1eda22009-05-06 16:02:58 -0700750 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700751 Enable PIN 1 of APIC timer
752 Can be useful to work around chipset bugs
753 (in particular on some ATI chipsets).
754 The kernel tries to set a reasonable default.
755
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 enforcing [SELINUX] Set initial enforcing status.
757 Format: {"0" | "1"}
758 See security/selinux/Kconfig help text.
759 0 -- permissive (log only, no denials).
760 1 -- enforcing (deny and log).
761 Default value is 0.
762 Value can be changed at runtime via /selinux/enforce.
763
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 ether= [HW,NET] Ethernet cards parameters
765 This option is obsoleted by the "netdev=" option, which
766 has equivalent usage. See its documentation for details.
767
768 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
769 Format: <io>[,<irq>]
770
Akinobu Mitade1ba092006-12-08 02:39:42 -0800771 failslab=
772 fail_page_alloc=
773 fail_make_request=[KNL]
774 General fault injection mechanism.
775 Format: <interval>,<probability>,<space>,<times>
776 See also /Documentation/fault-injection/.
777
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 fd_mcs= [HW,SCSI]
779 See header of drivers/scsi/fd_mcs.c.
780
781 fdomain= [HW,SCSI]
782 See header of drivers/scsi/fdomain.c.
783
784 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000785 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
Alex Chiangf13ae302008-05-08 14:03:23 -0600787 force_pal_cache_flush
788 [IA-64] Avoid check_sal_cache_flush which may hang on
789 buggy SAL_CACHE_FLUSH implementations. Using this
790 parameter will force ia64_sal_cache_flush to call
791 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
792
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100793 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400794 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100795 as early as possible in order to facilitate early
796 boot debugging.
797
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200798 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400799 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200800 If no parameter is passed, ftrace will dump
801 buffers of all CPUs, but if you pass orig_cpu, it will
802 dump only the buffer of the CPU that triggered the
803 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400804
805 ftrace_filter=[function-list]
806 [FTRACE] Limit the functions traced by the function
807 tracer at boot up. function-list is a comma separated
808 list of functions. This list can be changed at run
809 time by the set_ftrace_filter file in the debugfs
810 tracing directory.
811
812 ftrace_notrace=[function-list]
813 [FTRACE] Do not trace the functions specified in
814 function-list. This list can be changed at run time
815 by the set_ftrace_notrace file in the debugfs
816 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100817
Stefan Assmann369bc182009-10-12 22:17:21 +0200818 ftrace_graph_filter=[function-list]
819 [FTRACE] Limit the top level callers functions traced
820 by the function graph tracer at boot up.
821 function-list is a comma separated list of functions
822 that can be changed at run time by the
823 set_graph_function file in the debugfs tracing directory.
824
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 gamecon.map[2|3]=
826 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
827 support via parallel port (up to 5 devices per port)
828 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
829 See also Documentation/input/joystick-parport.txt
830
831 gamma= [HW,DRM]
832
Yinghai Luaaf23042008-01-30 13:33:09 +0100833 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
834 Format: off | on
835 default: on
836
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700837 gcov_persist= [GCOV] When non-zero (default), profiling data for
838 kernel modules is saved and remains accessible via
839 debugfs, even when the module is unloaded/reloaded.
840 When zero, profiling data is discarded and associated
841 debugfs files are removed at module unload time.
842
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 gdth= [HW,SCSI]
844 See header of drivers/scsi/gdth.c.
845
846 gpt [EFI] Forces disk with valid GPT signature but
847 invalid Protective MBR to be treated as GPT.
848
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 gvp11= [HW,SCSI]
850
851 hashdist= [KNL,NUMA] Large hashes allocated during boot
852 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700853 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700854 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
856 hcl= [IA-64] SGI's Hardware Graph compatibility layer
857
858 hd= [EIDE] (E)IDE hard drive subsystem geometry
859 Format: <cyl>,<head>,<sect>
860
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
862 size of <nn>. This works even on boxes that have no
863 highmem otherwise. This also works to reduce highmem
864 size on bigger boxes.
865
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800866 highres= [KNL] Enable/disable high resolution timer mode.
867 Valid parameters: "on", "off"
868 Default: "on"
869
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 hisax= [HW,ISDN]
871 See Documentation/isdn/README.HiSax.
872
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700873 hlt [BUGS=ARM,SH]
874
875 hpet= [X86-32,HPET] option to control HPET usage
876 Format: { enable (default) | disable | force |
877 verbose }
878 disable: disable HPET and use PIT instead
879 force: allow force enabled of undocumented chips (ICH4,
880 VIA, nVidia)
881 verbose: show contents of HPET registers during setup
882
Andi Kleenb4718e62008-07-23 21:27:51 -0700883 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
884 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700885 On x86-64 and powerpc, this option can be specified
886 multiple times interleaved with hugepages= to reserve
887 huge pages of different sizes. Valid pages sizes on
888 x86-64 are 2M (when the CPU supports "pse") and 1G
889 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700890 Note that 1GB pages can only be allocated at boot time
891 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900892
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100893 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
894 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100895 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
896 If specified, z/VM IUCV HVC accepts connections
897 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100898
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700899 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700900 or register an additional I2C bus that is not
901 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700902 Format:
903 <bus_id>,<clkrate>
904
Jiri Kosina36d95732008-10-06 02:51:09 -0400905 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200907 i8042.dumbkbd [HW] Pretend that controller can only read data from
908 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 (Don't attempt to blink the leds)
910 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500911 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400912 i8042.noloop [HW] Disable the AUX Loopback command while probing
913 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 i8042.nomux [HW] Don't check presence of an active multiplexing
915 controller
916 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
917 controllers
918 i8042.panicblink=
919 [HW] Frequency with which keyboard LEDs should blink
920 when kernel panics (default is 0.5 sec)
921 i8042.reset [HW] Reset the controller during init and cleanup
922 i8042.unlock [HW] Unlock (ignore) the keylock
923
924 i810= [HW,DRM]
925
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700926 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
927 indicates that the driver is running on unsupported
928 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
930 does not match list of supported models.
931 i8k.power_status
932 [HW] Report power status in /proc/i8k
933 (disabled by default)
934 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
935 capability is set.
936
937 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
938 See Documentation/mca.txt.
939
940 icn= [HW,ISDN]
941 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
942
David Fries0af80c02009-02-25 20:28:21 +0100943 ide-core.nodma= [HW] (E)IDE subsystem
944 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200945 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
946 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100947 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700949 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
950 Claim all unknown PCI IDE storage controllers.
951
Andi Kleenf039b752007-05-02 19:27:12 +0200952 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800953 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
954 Poll forces a polling idle loop that can slightly
955 improve the performance of waking up a idle CPU, but
956 will use a lot of power and make the system run hot.
957 Not recommended.
958 idle=mwait: On systems which support MONITOR/MWAIT but
959 the kernel chose to not use it because it doesn't save
960 as much power as a normal idle loop, use the
961 MONITOR/MWAIT idle loop anyways. Performance should be
962 the same as idle=poll.
963 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800964 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800965 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700966
Ingo Molnar792908222006-12-06 20:40:51 -0800967 ignore_loglevel [KNL]
968 Ignore loglevel setting - this will print /all/
969 kernel messages to the console. Useful for debugging.
970
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 ihash_entries= [KNL]
972 Set number of hash buckets for inode cache.
973
Mimi Zohar3323eec2009-02-04 09:06:58 -0500974 ima_audit= [IMA]
975 Format: { "0" | "1" }
976 0 -- integrity auditing messages. (Default)
977 1 -- enable informational integrity auditing messages.
978
979 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700980 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500981 default: "sha1"
982
Eric Paris5789ba32009-05-21 15:47:06 -0400983 ima_tcb [IMA]
984 Load a policy which meets the needs of the Trusted
985 Computing Base. This means IMA will measure all
986 programs exec'd, files mmap'd for exec, and all files
987 opened for read by uid=0.
988
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 in2000= [HW,SCSI]
990 See header of drivers/scsi/in2000.c.
991
992 init= [KNL]
993 Format: <full_path>
994 Run specified binary instead of /sbin/init as init
995 process.
996
997 initcall_debug [KNL] Trace initcalls as they are executed. Useful
998 for working out where the kernel is dying during
999 startup.
1000
1001 initrd= [BOOT] Specify the location of the initial ramdisk
1002
1003 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1004 Format: <irq>
1005
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001006 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001007 on
1008 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001009 off
1010 Disable intel iommu driver.
1011 igfx_off [Default Off]
1012 By default, gfx is mapped as normal device. If a gfx
1013 device has a dedicated DMAR unit, the DMAR unit is
1014 bypassed by not enabling DMAR with this option. In
1015 this case, gfx device will use physical address for
1016 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001017 forcedac [x86_64]
1018 With this option iommu will not optimize to look
1019 for io virtual address below 32 bit forcing dual
1020 address cycle on pci bus for cards supporting greater
1021 than 32 bit addressing. The default is to look
1022 for translation below 32 bit and if not available
1023 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001024 strict [Default Off]
1025 With this option on every unmap_single operation will
1026 result in a hardware IOTLB flush operation as opposed
1027 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001028
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001029 inttest= [IA64]
1030
1031 iomem= Disable strict checking of access to MMIO memory
1032 strict regions from userspace.
1033 relaxed
1034
1035 iommu= [x86]
1036 off
1037 force
1038 noforce
1039 biomerge
1040 panic
1041 nopanic
1042 merge
1043 nomerge
1044 forcesac
1045 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001046 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001047
1048 io7= [HW] IO7 for Marvel based alpha systems
1049 See comment before marvel_specify_io7 in
1050 arch/alpha/kernel/core_marvel.c.
1051
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301052 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001053 0x80
1054 Standard port 0x80 based delay
1055 0xed
1056 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001057 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001058 Simple two microseconds delay
1059 none
1060 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001061
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001063 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
1065 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001066 See comment before ip2_setup() in
1067 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068
1069 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1070 See header of drivers/scsi/ips.c.
1071
Alan Cox200803d2005-06-28 20:45:18 -07001072 irqfixup [HW]
1073 When an interrupt is not handled search all handlers
1074 for it. Intended to get systems with badly broken
1075 firmware running.
1076
1077 irqpoll [HW]
1078 When an interrupt is not handled search all handlers
1079 for it. Also check all handlers each timer
1080 interrupt. Intended to get systems with badly broken
1081 firmware running.
1082
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001084 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
1086 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001087 Format:
1088 <cpu number>,...,<cpu number>
1089 or
Li Zefanb225d442008-11-06 12:53:39 -08001090 <cpu number>-<cpu number>
1091 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001092 or a mixture
1093 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001094
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 This option can be used to specify one or more CPUs
1096 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001097 algorithms. You can move a process onto or off an
1098 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 <cpu number> begins at 0 and the maximum value is
1100 "number of CPUs in system - 1".
1101
1102 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001103 alternative -- manually setting the CPU mask of all
1104 tasks in the system -- can cause problems and
1105 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106
Randy Dunlapa9913042005-10-23 12:57:11 -07001107 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
1109 js= [HW,JOY] Analog joystick
1110 See Documentation/input/joystick.txt.
1111
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001112 keepinitrd [HW,ARM]
1113
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301114 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001115 specifies the amount of memory usable by the kernel
1116 for non-movable allocations. The requested amount is
1117 spread evenly throughout all nodes in the system. The
1118 remaining memory in each node is used for Movable
1119 pages. In the event, a node is too small to have both
1120 kernelcore and Movable pages, kernelcore pages will
1121 take priority and other nodes will have a larger number
1122 of kernelcore pages. The Movable zone is used for the
1123 allocation of pages that may be reclaimed or moved
1124 by the page migration subsystem. This means that
1125 HugeTLB pages may not be allocated from this zone.
1126 Note that allocations like PTEs-from-HighMem still
1127 use the HighMem zone if it exists, and the Normal
1128 zone if it does not.
1129
Jason Wessel4fe1da42010-05-20 21:04:31 -05001130 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1131 Format: <Controller#>[,poll interval]
1132 The controller # is the number of the ehci usb debug
1133 port as it is probed via PCI. The poll interval is
1134 optional and is the number seconds in between
1135 each poll cycle to the debug port in case you need
1136 the functionality for interrupting the kernel with
1137 gdb or control-c on the dbgp connection. When
1138 not using this parameter you use sysrq-g to break into
1139 the kernel debugger.
1140
Jason Wessel84c08fd2010-05-20 21:04:24 -05001141 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001142 Requires a tty driver that supports console polling,
1143 or a supported polling keyboard driver (non-usb).
1144 Serial only format: <serial_device>[,baud]
1145 keyboard only format: kbd
1146 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001147
Jason Wessel84c08fd2010-05-20 21:04:24 -05001148 kgdbwait [KGDB] Stop kernel execution and enter the
1149 kernel debugger at the earliest opportunity.
1150
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001151 kmac= [MIPS] korina ethernet MAC address.
1152 Configure the RouterBoard 532 series on-chip
1153 Ethernet adapter MAC address.
1154
Catalin Marinas04f70332009-06-11 13:22:39 +01001155 kmemleak= [KNL] Boot-time kmemleak enable/disable
1156 Valid arguments: on, off
1157 Default: on
1158
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301159 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001160 in oops dumps.
1161
Andre Przywarafef07aa2009-07-10 14:20:35 +02001162 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1163 Default is 0 (don't ignore, but inject #GP)
1164
1165 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1166 Default is 1 (enabled)
1167
1168 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1169 Default is 0 (off)
1170
1171 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1172 for all guests.
1173 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1174
1175 kvm-intel.bypass_guest_pf=
1176 [KVM,Intel] Disables bypassing of guest page faults
1177 on Intel chips. Default is 1 (enabled)
1178
1179 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1180 (virtualized MMU) support on capable Intel chips.
1181 Default is 1 (enabled)
1182
1183 kvm-intel.emulate_invalid_guest_state=
1184 [KVM,Intel] Enable emulation of invalid guest states
1185 Default is 0 (disabled)
1186
1187 kvm-intel.flexpriority=
1188 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1189 Default is 1 (enabled)
1190
1191 kvm-intel.unrestricted_guest=
1192 [KVM,Intel] Disable unrestricted guest feature
1193 (virtualized real and unpaged mode) on capable
1194 Intel chips. Default is 1 (enabled)
1195
1196 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1197 feature (tagged TLBs) on capable Intel chips.
1198 Default is 1 (enabled)
1199
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 l2cr= [PPC]
1201
Robert Brosea78bfbf2008-03-29 07:20:23 +11001202 l3cr= [PPC]
1203
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001204 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001205 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301207 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001208 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001209
FD Camifcb71f62008-01-06 19:08:56 +01001210 libata.dma= [LIBATA] DMA control
1211 libata.dma=0 Disable all PATA and SATA DMA
1212 libata.dma=1 PATA and SATA Disk DMA only
1213 libata.dma=2 ATAPI (CDROM) DMA only
1214 libata.dma=4 Compact Flash DMA only
1215 Combinations also work, so libata.dma=3 enables DMA
1216 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001217
1218 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1219 libata.ignore_hpa=0 keep BIOS limits (default)
1220 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001221
Dave Jones78e70c22007-09-27 11:50:13 -04001222 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1223 when set.
1224 Format: <int>
1225
Tejun Heo33267322008-02-13 09:15:09 +09001226 libata.force= [LIBATA] Force configurations. The format is comma
1227 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001228 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001229 matching port, link or device. Basically, it matches
1230 the ATA ID string printed on console by libata. If
1231 the whole ID part is omitted, the last PORT and DEVICE
1232 values are used. If ID hasn't been specified yet, the
1233 configuration applies to all ports, links and devices.
1234
1235 If only DEVICE is omitted, the parameter applies to
1236 the port and all links and devices behind it. DEVICE
1237 number of 0 either selects the first device or the
1238 first fan-out link behind PMP device. It does not
1239 select the host link. DEVICE number of 15 selects the
1240 host link and device attached to it.
1241
1242 The VAL specifies the configuration to force. As long
1243 as there's no ambiguity shortcut notation is allowed.
1244 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1245 The following configurations can be forced.
1246
1247 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1248 Any ID with matching PORT is used.
1249
1250 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1251
1252 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1253 udma[/][16,25,33,44,66,100,133] notation is also
1254 allowed.
1255
1256 * [no]ncq: Turn on or off NCQ.
1257
Tejun Heo05944bd2008-08-13 20:19:09 +09001258 * nohrst, nosrst, norst: suppress hard, soft
1259 and both resets.
1260
Tejun Heo33267322008-02-13 09:15:09 +09001261 If there are multiple matching configurations changing
1262 the same attribute, the last one is used.
1263
Randy Dunlap7c4be252009-01-06 14:42:44 -08001264 lmb=debug [KNL] Enable lmb debug messages.
1265
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001267 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001269 lockd.nlm_grace_period=P [NFS] Assign grace period.
1270 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001272 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1273 Format: <integer>
1274
1275 lockd.nlm_timeout=T [NFS] Assign timeout value.
1276 Format: <integer>
1277
1278 lockd.nlm_udpport=M [NFS] Assign UDP port.
1279 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
1281 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1282 Format: <irq>
1283
1284 loglevel= All Kernel Messages with a loglevel smaller than the
1285 console loglevel will be printed to the console. It can
1286 also be changed with klogd or other programs. The
1287 loglevels are defined as follows:
1288
1289 0 (KERN_EMERG) system is unusable
1290 1 (KERN_ALERT) action must be taken immediately
1291 2 (KERN_CRIT) critical conditions
1292 3 (KERN_ERR) error conditions
1293 4 (KERN_WARNING) warning conditions
1294 5 (KERN_NOTICE) normal but significant condition
1295 6 (KERN_INFO) informational
1296 7 (KERN_DEBUG) debug-level messages
1297
1298 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001299 Format: { n | nk | nM }
1300 n must be a power of two. The default size
1301 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302
Randy Dunlapaccaa242007-10-16 01:29:37 -07001303 logo.nologo [FB] Disables display of the built-in Linux logo.
1304 This may be used to provide more screen space for
1305 kernel log messages and is useful when debugging
1306 kernel boot problems.
1307
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 lp=0 [LP] Specify parallel ports to use, e.g,
1309 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1310 lp=reset first parallel port). 'lp=0' disables the
1311 lp=auto printer driver. 'lp=reset' (which can be
1312 specified in addition to the ports) causes
1313 attached printers to be reset. Using
1314 lp=port1,port2,... specifies the parallel ports
1315 to associate lp devices with, starting with
1316 lp0. A port specification may be 'none' to skip
1317 that lp device, or a parport name such as
1318 'parport0'. Specifying 'lp=auto' instead of a
1319 port specification list means that device IDs
1320 from each port should be examined, to see if
1321 an IEEE 1284-compliant printer is attached; if
1322 so, the driver will manage that printer.
1323 See also header of drivers/char/lp.c.
1324
1325 lpj=n [KNL]
1326 Sets loops_per_jiffy to given constant, thus avoiding
1327 time-consuming boot-time autodetection (up to 250 ms per
1328 CPU). 0 enables autodetection (default). To determine
1329 the correct value for your kernel, boot with normal
1330 autodetection and see what value is printed. Note that
1331 on SMP systems the preset will be applied to all CPUs,
1332 which is likely to cause problems if your CPUs need
1333 significantly divergent settings. An incorrect value
1334 will cause delays in the kernel to be wrong, leading to
1335 unpredictable I/O errors and other breakage. Although
1336 unlikely, in the extreme case this might damage your
1337 hardware.
1338
1339 ltpc= [NET]
1340 Format: <io>,<irq>,<dma>
1341
Randy Dunlapa9913042005-10-23 12:57:11 -07001342 mac5380= [HW,SCSI] Format:
1343 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344
Randy Dunlapa9913042005-10-23 12:57:11 -07001345 machvec= [IA64] Force the use of a particular machine-vector
1346 (machvec) in a generic kernel.
1347 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348
Wu Zhangjin3209e702009-07-02 23:27:12 +08001349 machtype= [Loongson] Share the same kernel image file between different
1350 yeeloong laptop.
1351 Example: machtype=lemote-yeeloong-2f-7inch
1352
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001353 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1354 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355
1356 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001357 should make use of. maxcpus=n : n >= 0 limits the
1358 kernel to using 'n' processors. n=0 is a special case,
1359 it is equivalent to "nosmp", which also disables
1360 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001362 max_loop= [LOOP] Maximum number of loopback devices that can
1363 be mounted
1364 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001365
Randy Dunlapa9913042005-10-23 12:57:11 -07001366 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 Should be between 1 and 2^32-1.
1368
1369 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001370 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 Should be between 1 and 16384.
1372
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 mcatest= [IA-64]
1374
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001375 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376
Uwe Hermann71cced62008-10-20 09:32:21 -07001377 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001378
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 md= [HW] RAID subsystems devices and level
1380 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 mdacon= [MDA]
1383 Format: <first>,<last>
1384 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1387 Amount of memory to be used when the kernel is not able
1388 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001389 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 address space collisions. Without memmap= PCI devices
1391 could be placed at addresses belonging to unused RAM.
1392
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001393 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 memory.
1395
Paul Mundt6902aa82008-09-21 17:14:42 +09001396 memchunk=nn[KMG]
1397 [KNL,SH] Allow user to override the default size for
1398 per-device physically contiguous DMA buffers.
1399
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301400 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 E820 memory map, as specified by the user.
1402 Such memmap=exactmap lines can be constructed based on
1403 BIOS output or other requirements. See the memmap=nn@ss
1404 option description.
1405
1406 memmap=nn[KMG]@ss[KMG]
1407 [KNL] Force usage of a specific region of memory
1408 Region of memory to be used, from ss to ss+nn.
1409
1410 memmap=nn[KMG]#ss[KMG]
1411 [KNL,ACPI] Mark specific memory as ACPI data.
1412 Region of memory to be used, from ss to ss+nn.
1413
1414 memmap=nn[KMG]$ss[KMG]
1415 [KNL,ACPI] Mark specific memory as reserved.
1416 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001417 Example: Exclude memory from 0x18690000-0x1869ffff
1418 memmap=64K$0x18690000
1419 or
1420 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001422 memory_corruption_check=0/1 [X86]
1423 Some BIOSes seem to corrupt the first 64k of
1424 memory when doing things like suspend/resume.
1425 Setting this option will scan the memory
1426 looking for corruption. Enabling this will
1427 both detect corruption and prevent the kernel
1428 from using the memory being corrupted.
1429 However, its intended as a diagnostic tool; if
1430 repeatable BIOS-originated corruption always
1431 affects the same memory, you can use memmap=
1432 to prevent the kernel from using that memory.
1433
1434 memory_corruption_check_size=size [X86]
1435 By default it checks for corruption in the low
1436 64k, making this memory unavailable for normal
1437 use. Use this parameter to scan for
1438 corruption in more or less memory.
1439
1440 memory_corruption_check_period=seconds [X86]
1441 By default it checks for corruption every 60
1442 seconds. Use this parameter to check at some
1443 other rate. 0 disables periodic checking.
1444
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001445 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001446 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001447 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001448 Specifies the number of memtest passes to be
1449 performed. Each pass selects another test
1450 pattern from a given set of patterns. Memtest
1451 fills the memory with this pattern, validates
1452 memory contents and reserves bad memory
1453 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001454
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 meye.*= [HW] Set MotionEye Camera parameters
1456 See Documentation/video4linux/meye.txt.
1457
Andres Salomon8f368812007-10-12 23:04:06 +02001458 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1459 Multi-Function General Purpose Timers on AMD Geode
1460 platforms.
1461
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001462 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1463 the BIOS has incorrectly applied a workaround. TinyBIOS
1464 version 0.98 is known to be affected, 0.99 fixes the
1465 problem by letting the user disable the workaround.
1466
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467 mga= [HW,DRM]
1468
Randy Dunlap1c207f92008-11-19 15:36:16 -08001469 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1470 physical address is ignored.
1471
Michel Pollet39f45d72009-05-20 11:10:31 +01001472 mini2440= [ARM,HW,KNL]
1473 Format:[0..2][b][c][t]
1474 Default: "0tb"
1475 MINI2440 configuration specification:
1476 0 - The attached screen is the 3.5" TFT
1477 1 - The attached screen is the 7" TFT
1478 2 - The VGA Shield is attached (1024x768)
1479 Leaving out the screen size parameter will not load
1480 the TFT driver, and the framebuffer will be left
1481 unconfigured.
1482 b - Enable backlight. The TFT backlight pin will be
1483 linked to the kernel VESA blanking code and a GPIO
1484 LED. This parameter is not necessary when using the
1485 VGA shield.
1486 c - Enable the s3c camera interface.
1487 t - Reserved for enabling touchscreen support. The
1488 touchscreen support is not enabled in the mainstream
1489 kernel as of 2.6.30, a preliminary port can be found
1490 in the "bleeding edge" mini2440 support kernel at
1491 http://repo.or.cz/w/linux-2.6/mini2440.git
1492
Mel Gorman6b74ab92008-07-23 21:26:49 -07001493 mminit_loglevel=
1494 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1495 parameter allows control of the logging verbosity for
1496 the additional memory initialisation checks. A value
1497 of 0 disables mminit logging and a level of 4 will
1498 log everything. Information is printed at KERN_DEBUG
1499 so loglevel=8 may also need to be specified.
1500
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 mousedev.tap_time=
1502 [MOUSE] Maximum time between finger touching and
1503 leaving touchpad surface for touch to be considered
1504 a tap and be reported as a left button click (for
1505 touchpads working in absolute mode only).
1506 Format: <msecs>
1507 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1508 reporting absolute coordinates, such as tablets
1509 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1510 reporting absolute coordinates, such as tablets
1511
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301512 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001513 is similar to kernelcore except it specifies the
1514 amount of memory used for migratable allocations.
1515 If both kernelcore and movablecore is specified,
1516 then kernelcore will be at *least* the specified
1517 value but may be more. If movablecore on its own
1518 is specified, the administrator must be careful
1519 that the amount of memory usable for all allocations
1520 is not too small.
1521
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 mpu401= [HW,OSS]
1523 Format: <io>,<irq>
1524
1525 MTD_Partition= [MTD]
1526 Format: <name>,<region-number>,<size>,<offset>
1527
Randy Dunlapa9913042005-10-23 12:57:11 -07001528 MTD_Region= [MTD] Format:
1529 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
1531 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001532 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001534 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1535
1536 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1537
1538 boundary - index of last SLC block on Flex-OneNAND.
1539 The remaining blocks are configured as MLC blocks.
1540 lock - Configure if Flex-OneNAND boundary should be locked.
1541 Once locked, the boundary cannot be changed.
1542 1 indicates lock status, 0 indicates unlock status.
1543
Ben Dooks9db829f2008-07-03 11:24:29 +01001544 mtdset= [ARM]
1545 ARM/S3C2412 JIVE boot control
1546
1547 See arch/arm/mach-s3c2412/mach-jive.c
1548
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001550 [HW] Make the MicroTouch USB driver use raw coordinates
1551 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001553 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001554 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001555 that could hold holes aka. UC entries.
1556
1557 mtrr_gran_size=nn[KMG] [X86]
1558 Used for mtrr cleanup. It is granularity of mtrr block.
1559 Default is 1.
1560 Large value could prevent small alignment from
1561 using up MTRRs.
1562
1563 mtrr_spare_reg_nr=n [X86]
1564 Format: <integer>
1565 Range: 0,7 : spare reg number
1566 Default : 1
1567 Used for mtrr cleanup. It is spare mtrr entries number.
1568 Set to 2 or more if your graphical card needs more.
1569
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1571
1572 NCR_D700= [HW,SCSI]
1573 See header of drivers/scsi/NCR_D700.c.
1574
1575 ncr5380= [HW,SCSI]
1576
1577 ncr53c400= [HW,SCSI]
1578
1579 ncr53c400a= [HW,SCSI]
1580
1581 ncr53c406a= [HW,SCSI]
1582
1583 ncr53c8xx= [HW,SCSI]
1584
1585 netdev= [NET] Network devices parameters
1586 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1587 Note that mem_start is often overloaded to mean
1588 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001589 This usage is only documented in each driver source
1590 file if at all.
1591
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001592 nf_conntrack.acct=
1593 [NETFILTER] Enable connection tracking flow accounting
1594 0 to disable accounting
1595 1 to enable accounting
1596 Default value depends on CONFIG_NF_CT_ACCT that is
1597 going to be removed in 2.6.29.
1598
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001600 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601
1602 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001603 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
Trond Myklebusta72b4422006-01-03 09:55:41 +01001605 nfs.callback_tcpport=
1606 [NFS] set the TCP port on which the NFSv4 callback
1607 channel should listen.
1608
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001609 nfs.cache_getent=
1610 [NFS] sets the pathname to the program which is used
1611 to update the NFS client cache entries.
1612
1613 nfs.cache_getent_timeout=
1614 [NFS] sets the timeout after which an attempt to
1615 update a cache entry is deemed to have failed.
1616
Trond Myklebust58df0952006-01-03 09:55:57 +01001617 nfs.idmap_cache_timeout=
1618 [NFS] set the maximum lifetime for idmapper cache
1619 entries.
1620
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001621 nfs.enable_ino64=
1622 [NFS] enable 64-bit inode numbers.
1623 If zero, the NFS client will fake up a 32-bit inode
1624 number for the readdir() and stat() syscalls instead
1625 of returning the full 64-bit number.
1626 The default is to return 64-bit inode numbers.
1627
Paul Mundt1e1030d2009-09-01 17:38:32 +09001628 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001629 when a NMI is triggered.
1630 Format: [state][,regs][,debounce][,die]
1631
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301632 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001633 Format: [panic,][num]
1634 Valid num: 0,1,2
1635 0 - turn nmi_watchdog off
1636 1 - use the IO-APIC timer for the NMI watchdog
1637 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001638 a performance counter. Note: This will use one
1639 performance counter and the local APIC's performance
1640 vector.
1641 When panic is specified, panic when an NMI watchdog
1642 timeout occurs.
1643 This is useful when you use a panic=... timeout and
1644 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001645 Instead of 1 and 2 it is possible to use the following
1646 symbolic names: lapic and ioapic
1647 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648
Anton Vorontsovbff38772009-07-08 11:10:56 -07001649 netpoll.carrier_timeout=
1650 [NET] Specifies amount of time (in seconds) that
1651 netpoll should wait for a carrier. By default netpoll
1652 waits 4 seconds.
1653
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001654 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 emulation library even if a 387 maths coprocessor
1656 is present.
1657
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001658 no_console_suspend
1659 [HW] Never suspend the console
1660 Disable suspending of consoles during suspend and
1661 hibernate operations. Once disabled, debugging
1662 messages can reach various consoles while the rest
1663 of the system is being put to sleep (ie, while
1664 debugging driver suspend/resume hooks). This may
1665 not work reliably with all consoles, but is known
1666 to work with serial and VGA consoles.
1667
Christoph Lameterc1aee212007-05-31 00:40:47 -07001668 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1669 caches in the slab allocator. Saves per-node memory,
1670 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001671
Randy Dunlapa9913042005-10-23 12:57:11 -07001672 noalign [KNL,ARM]
1673
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674 noapic [SMP,APIC] Tells the kernel to not make use of any
1675 IOAPICs that may be present in the system.
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 nobats [PPC] Do not use BATs for mapping kernel lowmem
1678 on "Classic" PPC cores.
1679
1680 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001681
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001682 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1683
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001684 nodelayacct [KNL] Disable per-task delay accounting
1685
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1687
Paul Mundt6902aa82008-09-21 17:14:42 +09001688 nodsp [SH] Disable hardware DSP at boot time.
1689
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301690 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001691
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 noexec [IA-64]
1693
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301694 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001695 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001697 noexec=off: disable non-executable mappings
1698
1699 noexec32 [X86-64]
1700 This affects only 32-bit executables.
1701 noexec32=on: enable non-executable mappings (default)
1702 read doesn't imply executable mappings
1703 noexec32=off: disable non-executable mappings
1704 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705
Paul Mundt6902aa82008-09-21 17:14:42 +09001706 nofpu [SH] Disable hardware FPU at boot time.
1707
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001708 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001709 register save and restore. The kernel will only save
1710 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711
Suresh Siddha0c752a92009-05-22 12:17:45 -07001712 noxsave [BUGS=X86] Disables x86 extended register state save
1713 and restore using xsave. The kernel will fallback to
1714 enabling legacy floating-point and sse state.
1715
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001716 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1717 wfi(ARM) instruction doesn't work correctly and not to
1718 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001719
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001720 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 instruction doesn't work correctly and not to
1722 use it.
1723
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001724 no_file_caps Tells the kernel not to honor file capabilities. The
1725 only way then for a file to be executed with privilege
1726 is to be setuid root or executed by root.
1727
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 nohalt [IA-64] Tells the kernel not to use the power saving
1729 function PAL_HALT_LIGHT when idle. This increases
1730 power-consumption. On the positive side, it reduces
1731 interrupt wake-up latency, which may improve performance
1732 in certain environments such as networked servers or
1733 real-time systems.
1734
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001735 nohz= [KNL] Boottime enable/disable dynamic ticks
1736 Valid arguments: on, off
1737 Default: on
1738
Paul Mundteeee7852009-04-02 12:31:16 +09001739 noiotrap [SH] Disables trapped I/O port accesses.
1740
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001741 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 disable unhandled interrupt sources.
1743
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301744 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001745 broken timer IRQ sources.
1746
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 noisapnp [ISAPNP] Disables ISA PnP code.
1748
1749 noinitrd [RAM] Tells the kernel not to load any configured
1750 initial RAM disk.
1751
Weidong Han03ea8152009-04-17 16:42:15 +08001752 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1753 remapping.
1754
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 nointroute [IA-64]
1756
Tony Luck0aa366f2007-07-20 11:22:30 -07001757 nojitter [IA64] Disables jitter checking for ITC timers.
1758
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001759 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001761 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001762
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 noltlbs [PPC] Do not use large page/tlb entries for kernel
1764 lowmem mapping on PPC40x.
1765
Horms312f1f02006-02-22 09:57:55 +09001766 nomca [IA-64] Disable machine check abort handling
1767
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001768 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001769
Andres Salomon83d73842007-10-12 23:04:06 +02001770 nomfgpt [X86-32] Disable Multi-Function General Purpose
1771 Timer usage (for AMD Geode machines).
1772
Jiri Kosina016ddd92010-01-18 17:05:40 +01001773 nopat [X86] Disable PAT (page attribute table extension of
1774 pagetables) support.
1775
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001776 norandmaps Don't use address space randomization. Equivalent to
1777 echo 0 > /proc/sys/kernel/randomize_va_space
1778
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001779 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001780
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001781 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001782 with UP alternatives
1783
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 noresidual [PPC] Don't use residual data on PReP machines.
1785
Randy Dunlapa9913042005-10-23 12:57:11 -07001786 noresume [SWSUSP] Disables resume and restores original swap
1787 space.
1788
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 no-scroll [VGA] Disables scrollback.
1790 This is required for the Braillex ib80-piezo Braille
1791 reader made by F.H. Papenmeier (Germany).
1792
1793 nosbagart [IA-64]
1794
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001795 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001796
Len Brown61ec7562007-08-16 03:34:22 -04001797 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1798 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799
Dave Jones97842212007-07-15 23:41:05 -07001800 nosoftlockup [KNL] Disable the soft-lockup detector.
1801
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001802 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001803 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001804
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805 nosync [HW,M68K] Disables sync negotiation for all devices.
1806
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001807 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808
1809 nousb [USB] Disable the USB subsystem
1810
1811 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001812
Weidong Han2b2fd872009-04-17 16:42:12 +08001813 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1814
Fenghua Yua6c75b862008-03-14 13:57:08 -07001815 nptcg= [IA64] Override max number of concurrent global TLB
1816 purges which is reported from either PAL_VM_SUMMARY or
1817 SAL PALO.
1818
Yinghai Lu2b633e32010-02-10 01:20:37 -08001819 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1820 could support. nr_cpus=n : n >= 1 limits the kernel to
1821 supporting 'n' processors. Later in runtime you can not
1822 use hotplug cpu feature to put more cpu back to online.
1823 just like you compile the kernel NR_CPUS=n
1824
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001825 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1826
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001827 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1828 one of ['zone', 'node', 'default'] can be specified
1829 This can be set from sysctl after boot.
1830 See Documentation/sysctl/vm.txt for details.
1831
Randy Dunlap7c4be252009-01-06 14:42:44 -08001832 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1833 See Documentation/debugging-via-ohci1394.txt for more
1834 info.
1835
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001836 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1837 Rather than timing out after 20 ms if an EC
1838 command is not properly ACKed, override the length
1839 of the timeout. We have interrupts disabled while
1840 waiting for the ACK, so if this is set too high
1841 interrupts *may* be lost!
1842
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001843 omap_mux= [OMAP] Override bootloader pin multiplexing.
1844 Format: <mux_mode0.mode_name=value>...
1845 For example, to override I2C bus2:
1846 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1847
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 opl3= [HW,OSS]
1849 Format: <io>
1850
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851 oprofile.timer= [HW]
1852 Use timer interrupt instead of performance counters
1853
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001854 oprofile.cpu_type= Force an oprofile cpu type
1855 This might be useful if you have an older oprofile
1856 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001857 Format: { arch_perfmon }
1858 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001859 perfmon on Intel CPUs instead of the
1860 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001861
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 osst= [HW,SCSI] SCSI Tape Driver
1863 Format: <buffer_size>,<write_threshold>
1864 See also Documentation/scsi/st.txt.
1865
1866 panic= [KNL] Kernel behaviour on panic
1867 Format: <timeout>
1868
1869 parkbd.port= [HW] Parallel port number the keyboard adapter is
1870 connected to, default is 0.
1871 Format: <parport#>
1872 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1873 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001874 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875
Randy Dunlapa9913042005-10-23 12:57:11 -07001876 parport= [HW,PPT] Specify parallel ports. 0 disables.
1877 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1878 Use 'auto' to force the driver to use any
1879 IRQ/DMA settings detected (the default is to
1880 ignore detected IRQ/DMA settings because of
1881 possible conflicts). You can specify the base
1882 address, IRQ, and DMA settings; IRQ and DMA
1883 should be numbers, or 'auto' (for using detected
1884 settings on that particular port), or 'nofifo'
1885 (to avoid using a FIFO even if it is detected).
1886 Parallel ports are assigned in the order they
1887 are specified on the command line, starting
1888 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889
Randy Dunlapa9913042005-10-23 12:57:11 -07001890 parport_init_mode= [HW,PPT]
1891 Configure VIA parallel port to operate in
1892 a specific mode. This is necessary on Pegasos
1893 computer where firmware has no options for setting
1894 up parallel port mode and sets it to spp.
1895 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 Format: [spp|ps2|epp|ecp|ecpepp]
1897
Randy Dunlapa9913042005-10-23 12:57:11 -07001898 pas2= [HW,OSS] Format:
1899 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1900
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 pas16= [HW,SCSI]
1902 See header of drivers/scsi/pas16.c.
1903
Andrew Mortondd287792006-03-23 03:00:57 -08001904 pause_on_oops=
1905 Halt all CPUs after the first oops has been printed for
1906 the specified number of seconds. This is to be used if
1907 your oopses keep scrolling off the screen.
1908
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 pcbit= [HW,ISDN]
1910
1911 pcd. [PARIDE]
1912 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001913 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914
Randy Dunlapa9913042005-10-23 12:57:11 -07001915 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001916 earlydump [X86] dump PCI config space before the kernel
1917 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001918 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001919 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001920 the hardware directly. Use this if your machine
1921 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001922 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001923 hardware access methods are allowed. Use this
1924 if you experience crashes upon bootup and you
1925 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001926 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001927 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001928 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001929 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001930 noaer [PCIE] If the PCIEAER kernel config parameter is
1931 enabled, this kernel boot option can be used to
1932 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001933 nodomains [PCI] Disable support for multiple PCI
1934 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301935 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001936 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001937 check_enable_amd_mmconf [X86] check for and enable
1938 properly configured MMIO access to PCI
1939 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001940 nomsi [MSI] If the PCI_MSI kernel config parameter is
1941 enabled, this kernel boot option can be used to
1942 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001943 noioapicquirk [APIC] Disable all boot interrupt quirks.
1944 Safety option to keep boot IRQs enabled. This
1945 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001946 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1947 primary IO-APIC for bridges that cannot disable
1948 boot IRQs. This fixes a source of spurious IRQs
1949 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001950 noioapicreroute [APIC] Disable workaround that uses the
1951 boot IRQ equivalent of an IRQ that connects to
1952 a chipset where boot IRQs cannot be disabled.
1953 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001954 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001955 routing table. These calls are known to be buggy
1956 on several machines and they hang the machine
1957 when used, but on other computers it's the only
1958 way to get the interrupt routing table. Try
1959 this option if the kernel is unable to allocate
1960 IRQs or discover secondary PCI buses on your
1961 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001962 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001963 Use with caution as certain devices share
1964 address decoders between ROMs and other
1965 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001966 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001967 expansion ROMs that do not already have
1968 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001969 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001970 assigned automatically to PCI devices. You can
1971 make the kernel exclude IRQs of your ISA cards
1972 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001973 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001974 of the PIRQ table (normally generated
1975 by the BIOS) if it is outside the
1976 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001977 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001978 useful if the kernel is unable to find your
1979 secondary buses and you want to tell it
1980 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001981 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001982 numbers ourselves, overriding
1983 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001984 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001985 in the BIOS $PIR table. This is needed on
1986 some systems with broken BIOSes, notably
1987 some HP Pavilion N5400 and Omnibook XE3
1988 notebooks. This will have no effect if ACPI
1989 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001990 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001991 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001992 use_crs [X86] Use PCI host bridge window information
1993 from ACPI. On BIOSes from 2008 or later, this
1994 is enabled by default. If you need to use this,
1995 please report a bug.
1996 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1997 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001998 routeirq Do IRQ routing for all PCI devices.
1999 This is normally done in pci_enable_device(),
2000 so this option is a temporary workaround
2001 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002002 skip_isa_align [X86] do not align io start addr, so can
2003 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002004 firmware [ARM] Do not re-enumerate the bus but instead
2005 just use the configuration from the
2006 bootloader. This is currently used on
2007 IXP2000 systems where the bus has to be
2008 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002009 noearly [X86] Don't do any early type 1 scanning.
2010 This might help on some broken boards which
2011 machine check when some devices' config space
2012 is read. But various workarounds are disabled
2013 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002014 bfsort Sort PCI devices into breadth-first order.
2015 This sorting is done to get a device
2016 order compatible with older (<= 2.4) kernels.
2017 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002018 cbiosize=nn[KMG] The fixed amount of bus space which is
2019 reserved for the CardBus bridge's IO window.
2020 The default value is 256 bytes.
2021 cbmemsize=nn[KMG] The fixed amount of bus space which is
2022 reserved for the CardBus bridge's memory
2023 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002024 resource_alignment=
2025 Format:
2026 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2027 Specifies alignment and device to reassign
2028 aligned memory resources.
2029 If <order of align> is not specified,
2030 PAGE_SIZE is used as alignment.
2031 PCI-PCI bridge can be specified, if resource
2032 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002033 ecrc= Enable/disable PCIe ECRC (transaction layer
2034 end-to-end CRC checking).
2035 bios: Use BIOS/firmware settings. This is the
2036 the default.
2037 off: Turn ECRC off
2038 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002039
Chuck Ebberte5665a42008-09-24 20:40:34 -04002040 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2041 Management.
2042 off Disable ASPM.
2043 force Enable ASPM even on devices that claim not to support it.
2044 WARNING: Forcing ASPM on may cause system lockups.
2045
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002046 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2047 off Do not use native PCIe PME signaling.
2048 force Use native PCIe PME signaling even if the BIOS refuses
2049 to allow the kernel to control the relevant PCIe config
2050 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002051 nomsi Do not use MSI for native PCIe PME signaling (this makes
2052 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002053
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054 pcmv= [HW,PCMCIA] BadgePAD 4
2055
2056 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002057 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058
2059 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2060 boot time.
2061 Format: { 0 | 1 }
2062 See arch/parisc/kernel/pdc_chassis.c
2063
Tejun Heof58dc012009-08-14 15:00:50 +09002064 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002065 Currently supported values are "embed" and "page".
2066 Archs may support subset or none of the selections.
2067 See comments in mm/percpu.c for details on each
2068 allocator. This parameter is primarily for debugging
2069 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002070
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002072 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073
2074 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002075 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076
2077 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002078 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079
2080 plip= [PPT,NET] Parallel port network link
2081 Format: { parport<nr> | timid | 0 }
2082 See also Documentation/parport.txt.
2083
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002084 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2085 Override pmtimer IOPort with a hex value.
2086 e.g. pmtmr=0x508
2087
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002088 pnp.debug [PNP]
2089 Enable PNP debug messages. This depends on the
2090 CONFIG_PNP_DEBUG_MESSAGES option.
2091
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 pnpacpi= [ACPI]
2093 { off }
2094
2095 pnpbios= [ISAPNP]
2096 { on | off | curr | res | no-curr | no-res }
2097
2098 pnp_reserve_irq=
2099 [ISAPNP] Exclude IRQs for the autoconfiguration
2100
2101 pnp_reserve_dma=
2102 [ISAPNP] Exclude DMAs for the autoconfiguration
2103
2104 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002105 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106
2107 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002108 [ISAPNP] Exclude memory regions for the
2109 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110 Ranges are in pairs (memory base and size).
2111
Randy Dunlap4af94f32009-04-17 18:30:28 -07002112 ports= [IP_VS_FTP] IPVS ftp helper module
2113 Default is 21.
2114 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2115 may be specified.
2116 Format: <port>,<port>....
2117
Ingo Molnar45807a12007-07-15 23:40:10 -07002118 print-fatal-signals=
2119 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002120
2121 If enabled, warn about various signal handling
2122 related application anomalies: too many signals,
2123 too many POSIX.1 timers, fatal signals causing a
2124 coredump - etc.
2125
2126 If you hit the warning due to signal overflow,
2127 you might want to try "ulimit -i unlimited".
2128
Ingo Molnar45807a12007-07-15 23:40:10 -07002129 default: off.
2130
Randy Dunlape84845c2007-07-15 23:40:25 -07002131 printk.time= Show timing data prefixed to each printk message line
2132 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2133
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002134 processor.max_cstate= [HW,ACPI]
2135 Limit processor to maximum C-state
2136 max_cstate=9 overrides any DMI blacklist limit.
2137
2138 processor.nocst [HW,ACPI]
2139 Ignore the _CST method to determine C-states,
2140 instead using the legacy FADT method
2141
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002143 Format: [schedule,]<number>
2144 Param: "schedule" - profile schedule points.
2145 Param: <number> - step/bucket size as a power of 2 for
2146 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002147 Param: "sleep" - profile D-state sleeping (millisecs).
2148 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002149 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150
Linus Torvalds1da177e2005-04-16 15:20:36 -07002151 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2152 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002153 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154
Randy Dunlapa9913042005-10-23 12:57:11 -07002155 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2156 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2158 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002159 psmouse.resetafter= [HW,MOUSE]
2160 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 (0 = never).
2162 psmouse.resolution=
2163 [HW,MOUSE] Set desired mouse resolution, in dpi.
2164 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002165 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 0 = disabled, 1 = enabled (default).
2167
2168 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002169 Format:
2170 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171
2172 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002173 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
Kay Sieversdc8c8582007-08-15 12:25:38 +02002175 pty.legacy_count=
2176 [KNL] Number of legacy pty's. Overwrites compiled-in
2177 default number.
2178
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002179 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002180
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 r128= [HW,DRM]
2182
2183 raid= [HW,RAID]
2184 See Documentation/md.txt.
2185
Randy Dunlapa9913042005-10-23 12:57:11 -07002186 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002187 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002188
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002190 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002192 rcupdate.blimit= [KNL,BOOT]
2193 Set maximum number of finished RCU callbacks to process
2194 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002195
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002196 rcupdate.qhimark= [KNL,BOOT]
2197 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002198 RCU callbacks over which batch limiting is disabled.
2199
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002200 rcupdate.qlowmark= [KNL,BOOT]
2201 Set threshold of queued RCU callbacks below which
2202 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002203
Olof Johanssonffdfc402005-09-06 15:17:19 -07002204 rdinit= [KNL]
2205 Format: <full_path>
2206 Run specified binary instead of /init from the ramdisk,
2207 used for early userspace startup. See initrd.
2208
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002209 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002211 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212
Paul Jackson46b6d942008-07-04 10:00:09 -07002213 relax_domain_level=
2214 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002215 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002216
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2218
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002219 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002220 Format: nn[KMG]
2221 Reserves a hole at the top of the kernel virtual
2222 address space.
2223
Vivek Goyal7e962872006-09-27 01:50:44 -07002224 reset_devices [KNL] Force drivers to reset the underlying device
2225 during initialization.
2226
Randy Dunlapa9913042005-10-23 12:57:11 -07002227 resume= [SWSUSP]
2228 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002230 resume_offset= [SWSUSP]
2231 Specify the offset from the beginning of the partition
2232 given by "resume=" at which the swap header is located,
2233 in <PAGE_SIZE> units (needed only for swap files).
2234 See Documentation/power/swsusp-and-swap-files.txt
2235
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002236 retain_initrd [RAM] Keep initrd memory after extraction
2237
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 rhash_entries= [KNL,NET]
2239 Set number of hash buckets for route cache
2240
2241 riscom8= [HW,SERIAL]
2242 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2243
2244 ro [KNL] Mount root device read-only on boot
2245
2246 root= [KNL] Root filesystem
2247
2248 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2249 mount the root filesystem
2250
2251 rootflags= [KNL] Set root filesystem mount option string
2252
2253 rootfstype= [KNL] Set root filesystem type
2254
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002255 rootwait [KNL] Wait (indefinitely) for root device to show up.
2256 Useful for devices that are detected asynchronously
2257 (e.g. USB and MMC devices).
2258
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259 rw [KNL] Mount root device read-write on boot
2260
2261 S [KNL] Run init in single mode
2262
2263 sa1100ir [NET]
2264 See drivers/net/irda/sa1100_ir.c.
2265
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002267
Mike Travisf6630112009-11-17 18:22:15 -06002268 sched_debug [KNL] Enables verbose scheduler debug messages.
2269
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2271 Format: <io>[,<timeout>[,<isapnp>]]
2272
2273 scsi_debug_*= [SCSI]
2274 See drivers/scsi/scsi_debug.c.
2275
2276 scsi_default_dev_flags=
2277 [SCSI] SCSI default device flags
2278 Format: <integer>
2279
2280 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2281 Format: <vendor>:<model>:<flags>
2282 (flags are integer value)
2283
Randy Dunlap6af66322007-11-14 16:52:25 -08002284 scsi_logging_level= [SCSI] a bit mask of logging levels
2285 See drivers/scsi/scsi_logging.h for bits. Also
2286 settable via sysctl at dev.scsi.logging_level
2287 (/proc/sys/dev/scsi/logging_level).
2288 There is also a nice 'scsi_logging_level' script in the
2289 S390-tools package, available for download at
2290 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002291
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002292 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2293 discovered. async scans them in kernel threads,
2294 allowing boot to proceed. none ignores them, expecting
2295 user space to do the scan.
2296
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002297 security= [SECURITY] Choose a security module to enable at boot.
2298 If this boot parameter is not specified, only the first
2299 security module asking for security registration will be
2300 loaded. An invalid security module name will be treated
2301 as if no module has been chosen.
2302
2303 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 Format: { "0" | "1" }
2305 See security/selinux/Kconfig help text.
2306 0 -- disable.
2307 1 -- enable.
2308 Default value is set via kernel config option.
2309 If enabled at boot time, /selinux/disable can be used
2310 later to disable prior to initial policy load.
2311
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002312 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313
Linus Torvalds1da177e2005-04-16 15:20:36 -07002314 shapers= [NET]
2315 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002316
Yinghai Lub05f78f2008-08-22 01:32:50 -07002317 show_msr= [x86] show boot-time MSR settings
2318 Format: { <integer> }
2319 Show boot-time (BIOS-initialized) MSR settings.
2320 The parameter means the number of CPUs to show,
2321 for example 1 means boot CPU only.
2322
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323 sim710= [SCSI,HW]
2324 See header of drivers/scsi/sim710.c.
2325
2326 simeth= [IA-64]
2327 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002328
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329 slram= [HW,MTD]
2330
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002331 slub_debug[=options[,slabs]] [MM, SLUB]
2332 Enabling slub_debug allows one to determine the
2333 culprit if slab objects become corrupted. Enabling
2334 slub_debug can create guard zones around objects and
2335 may poison objects when not in use. Also tracks the
2336 last alloc / free. For more information see
2337 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002338
2339 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002340 Determines the maximum allowed order for slabs.
2341 A high setting may cause OOMs due to memory
2342 fragmentation. For more information see
2343 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002344
2345 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002346 The minimum number of objects per slab. SLUB will
2347 increase the slab order up to slub_max_order to
2348 generate a sufficiently large slab able to contain
2349 the number of objects indicated. The higher the number
2350 of objects the smaller the overhead of tracking slabs
2351 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002352 For more information see Documentation/vm/slub.txt.
2353
2354 slub_min_order= [MM, SLUB]
2355 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002356 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002357 For more information see Documentation/vm/slub.txt.
2358
2359 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002360 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002361 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002362 allocs to different slabs. Debug options disable
2363 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002364 For more information see Documentation/vm/slub.txt.
2365
Linus Torvalds1da177e2005-04-16 15:20:36 -07002366 smart2= [HW]
2367 Format: <io1>[,<io2>[,...,<io8>]]
2368
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002369 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002370 attempt to substitute SMP alternatives once at boot.
2371
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002372 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2373 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2374 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2375 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2376 smsc-ircc2.ircc_irq= [HW] IRQ line
2377 smsc-ircc2.ircc_dma= [HW] DMA channel
2378 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2379 0: Toshiba Satellite 1800 (GP data pin select)
2380 1: Fast pin select (default)
2381 2: ATC IRMode
2382
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383 snd-ad1816a= [HW,ALSA]
2384
2385 snd-ad1848= [HW,ALSA]
2386
2387 snd-ali5451= [HW,ALSA]
2388
2389 snd-als100= [HW,ALSA]
2390
2391 snd-als4000= [HW,ALSA]
2392
2393 snd-azt2320= [HW,ALSA]
2394
2395 snd-cmi8330= [HW,ALSA]
2396
2397 snd-cmipci= [HW,ALSA]
2398
2399 snd-cs4231= [HW,ALSA]
2400
2401 snd-cs4232= [HW,ALSA]
2402
2403 snd-cs4236= [HW,ALSA]
2404
2405 snd-cs4281= [HW,ALSA]
2406
2407 snd-cs46xx= [HW,ALSA]
2408
2409 snd-dt019x= [HW,ALSA]
2410
2411 snd-dummy= [HW,ALSA]
2412
2413 snd-emu10k1= [HW,ALSA]
2414
2415 snd-ens1370= [HW,ALSA]
2416
2417 snd-ens1371= [HW,ALSA]
2418
2419 snd-es968= [HW,ALSA]
2420
2421 snd-es1688= [HW,ALSA]
2422
2423 snd-es18xx= [HW,ALSA]
2424
2425 snd-es1938= [HW,ALSA]
2426
2427 snd-es1968= [HW,ALSA]
2428
2429 snd-fm801= [HW,ALSA]
2430
2431 snd-gusclassic= [HW,ALSA]
2432
2433 snd-gusextreme= [HW,ALSA]
2434
2435 snd-gusmax= [HW,ALSA]
2436
2437 snd-hdsp= [HW,ALSA]
2438
2439 snd-ice1712= [HW,ALSA]
2440
2441 snd-intel8x0= [HW,ALSA]
2442
2443 snd-interwave= [HW,ALSA]
2444
2445 snd-interwave-stb=
2446 [HW,ALSA]
2447
2448 snd-korg1212= [HW,ALSA]
2449
2450 snd-maestro3= [HW,ALSA]
2451
2452 snd-mpu401= [HW,ALSA]
2453
2454 snd-mtpav= [HW,ALSA]
2455
2456 snd-nm256= [HW,ALSA]
2457
2458 snd-opl3sa2= [HW,ALSA]
2459
2460 snd-opti92x-ad1848=
2461 [HW,ALSA]
2462
2463 snd-opti92x-cs4231=
2464 [HW,ALSA]
2465
2466 snd-opti93x= [HW,ALSA]
2467
2468 snd-pmac= [HW,ALSA]
2469
2470 snd-rme32= [HW,ALSA]
2471
2472 snd-rme96= [HW,ALSA]
2473
2474 snd-rme9652= [HW,ALSA]
2475
2476 snd-sb8= [HW,ALSA]
2477
2478 snd-sb16= [HW,ALSA]
2479
2480 snd-sbawe= [HW,ALSA]
2481
2482 snd-serial= [HW,ALSA]
2483
2484 snd-sgalaxy= [HW,ALSA]
2485
2486 snd-sonicvibes= [HW,ALSA]
2487
2488 snd-sun-amd7930=
2489 [HW,ALSA]
2490
2491 snd-sun-cs4231= [HW,ALSA]
2492
2493 snd-trident= [HW,ALSA]
2494
2495 snd-usb-audio= [HW,ALSA,USB]
2496
2497 snd-via82xx= [HW,ALSA]
2498
2499 snd-virmidi= [HW,ALSA]
2500
2501 snd-wavefront= [HW,ALSA]
2502
2503 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002504
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002505 softlockup_panic=
2506 [KNL] Should the soft-lockup detector generate panics.
2507
Linus Torvalds1da177e2005-04-16 15:20:36 -07002508 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2509 See Documentation/sonypi.txt
2510
2511 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002512 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513
2514 spia_io_base= [HW,MTD]
2515 spia_fio_base=
2516 spia_pedr=
2517 spia_peddr=
2518
2519 sscape= [HW,OSS]
2520 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002521
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2523 See Documentation/scsi/st.txt.
2524
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002525 stacktrace [FTRACE]
2526 Enabled the stack tracer on boot up.
2527
Linus Torvalds1da177e2005-04-16 15:20:36 -07002528 sti= [PARISC,HW]
2529 Format: <num>
2530 Set the STI (builtin display/keyboard on the HP-PARISC
2531 machines) console (graphic card) which should be used
2532 as the initial boot-console.
2533 See also comment in drivers/video/console/sticore.c.
2534
2535 sti_font= [HW]
2536 See comment in drivers/video/console/sticore.c.
2537
2538 stifb= [HW]
2539 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2540
Trond Myklebustcbf11072009-08-09 15:06:19 -04002541 sunrpc.min_resvport=
2542 sunrpc.max_resvport=
2543 [NFS,SUNRPC]
2544 SunRPC servers often require that client requests
2545 originate from a privileged port (i.e. a port in the
2546 range 0 < portnr < 1024).
2547 An administrator who wishes to reserve some of these
2548 ports for other uses may adjust the range that the
2549 kernel's sunrpc client considers to be privileged
2550 using these two parameters to set the minimum and
2551 maximum port values.
2552
Greg Banks42a7fc42007-03-06 01:42:23 -08002553 sunrpc.pool_mode=
2554 [NFS]
2555 Control how the NFS server code allocates CPUs to
2556 service thread pools. Depending on how many NICs
2557 you have and where their interrupts are bound, this
2558 option will affect which CPUs will do NFS serving.
2559 Note: this parameter cannot be changed while the
2560 NFS server is running.
2561
2562 auto the server chooses an appropriate mode
2563 automatically using heuristics
2564 global a single global pool contains all CPUs
2565 percpu one pool for each CPU
2566 pernode one pool for each NUMA node (equivalent
2567 to global on non-NUMA machines)
2568
Trond Myklebustcbf11072009-08-09 15:06:19 -04002569 sunrpc.tcp_slot_table_entries=
2570 sunrpc.udp_slot_table_entries=
2571 [NFS,SUNRPC]
2572 Sets the upper limit on the number of simultaneous
2573 RPC calls that can be sent from the client to a
2574 server. Increasing these values may allow you to
2575 improve throughput, but will also increase the
2576 amount of memory reserved for use by the client.
2577
Linus Torvalds1da177e2005-04-16 15:20:36 -07002578 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002579
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580 switches= [HW,M68k]
2581
2582 sym53c416= [HW,SCSI]
2583 See header of drivers/scsi/sym53c416.c.
2584
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002585 sysrq_always_enabled
2586 [KNL]
2587 Ignore sysrq setting - this boot parameter will
2588 neutralize any effect of /proc/sys/kernel/sysrq.
2589 Useful for debugging.
2590
Linus Torvalds1da177e2005-04-16 15:20:36 -07002591 t128= [HW,SCSI]
2592 See header of drivers/scsi/t128.c.
2593
2594 tdfx= [HW,DRM]
2595
David Brownell77437fd2008-07-23 21:28:33 -07002596 test_suspend= [SUSPEND]
2597 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2598 standby suspend) as the system sleep state to briefly
2599 enter during system startup. The system is woken from
2600 this state using a wakeup-capable RTC alarm.
2601
Linus Torvalds1da177e2005-04-16 15:20:36 -07002602 thash_entries= [KNL,NET]
2603 Set number of hash buckets for TCP connection
2604
Len Brownf8707ec2007-08-12 00:12:54 -04002605 thermal.act= [HW,ACPI]
2606 -1: disable all active trip points in all thermal zones
2607 <degrees C>: override all lowest active trip points
2608
Len Brownc52a7412007-08-14 15:49:32 -04002609 thermal.crt= [HW,ACPI]
2610 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002611 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002612
Len Brownf5487142007-08-12 00:12:44 -04002613 thermal.nocrt= [HW,ACPI]
2614 Set to disable actions on ACPI thermal zone
2615 critical and hot trip points.
2616
Len Brown72b33ef2007-08-12 00:12:17 -04002617 thermal.off= [HW,ACPI]
2618 1: disable ACPI thermal control
2619
Len Browna70cdc52007-08-12 00:12:35 -04002620 thermal.psv= [HW,ACPI]
2621 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002622 <degrees C>: override all passive trip points to this
2623 value
Len Browna70cdc52007-08-12 00:12:35 -04002624
Len Brown730ff342007-08-12 00:12:26 -04002625 thermal.tzp= [HW,ACPI]
2626 Specify global default ACPI thermal zone polling rate
2627 <deci-seconds>: poll all this frequency
2628 0: no polling (default)
2629
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630 tmscsim= [HW,SCSI]
2631 See comment before function dc390_setup() in
2632 drivers/scsi/tmscsim.c.
2633
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002634 topology= [S390]
2635 Format: {off | on}
2636 Specify if the kernel should make use of the cpu
2637 topology informations if the hardware supports these.
2638 The scheduler will make use of these informations and
2639 e.g. base its process migration decisions on it.
2640 Default is off.
2641
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642 tp720= [HW,PS2]
2643
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002644 tpm_suspend_pcr=[HW,TPM]
2645 Format: integer pcr id
2646 Specify that at suspend time, the tpm driver
2647 should extend the specified pcr with zeros,
2648 as a workaround for some chips which fail to
2649 flush the last written pcr on TPM_SaveState.
2650 This will guarantee that all the other pcrs
2651 are saved.
2652
Li Zefan9d612be2009-06-24 17:33:15 +08002653 trace_buf_size=nn[KMG]
2654 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002655
Li Zefan020e5f82009-07-01 10:47:05 +08002656 trace_event=[event-list]
2657 [FTRACE] Set and start specified trace events in order
2658 to facilitate early boot debugging.
2659 See also Documentation/trace/events.txt
2660
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002662 Format:
2663 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2664
Alok Kataria395628e2008-10-24 17:22:01 -07002665 tsc= Disable clocksource-must-verify flag for TSC.
2666 Format: <string>
2667 [x86] reliable: mark tsc clocksource as reliable, this
2668 disables clocksource verification at runtime.
2669 Used to enable high-resolution timer mode on older
2670 hardware, and in virtualized environment.
2671
Randy Dunlapa9913042005-10-23 12:57:11 -07002672 turbografx.map[2|3]= [HW,JOY]
2673 TurboGraFX parallel port interface
2674 Format:
2675 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002676 See also Documentation/input/joystick-parport.txt
2677
2678 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2679 See header of drivers/scsi/u14-34f.c.
2680
2681 uart401= [HW,OSS]
2682 Format: <io>,<irq>
2683
2684 uart6850= [HW,OSS]
2685 Format: <io>,<irq>
2686
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002687 uhash_entries= [KNL,NET]
2688 Set number of hash buckets for UDP/UDP-Lite connections
2689
Alan Stern5f8364b2006-12-05 16:29:55 -05002690 uhci-hcd.ignore_oc=
2691 [USB] Ignore overcurrent events (default N).
2692 Some badly-designed motherboards generate lots of
2693 bogus events, for ports that aren't wired to
2694 anything. Set this parameter to avoid log spamming.
2695 Note that genuine overcurrent events won't be
2696 reported either.
2697
Simon Arlotte3a61b02008-07-19 23:32:54 +01002698 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302699 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002700 Set unknown_nmi_panic=1 early on boot.
2701
Alan Sternb5e795f2007-02-20 15:00:53 -05002702 usbcore.autosuspend=
2703 [USB] The autosuspend time delay (in seconds) used
2704 for newly-detected USB devices (default 2). This
2705 is the time required before an idle device will be
2706 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002707 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002708
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002709 usbcore.usbfs_snoop=
2710 [USB] Set to log all usbfs traffic (default 0 = off).
2711
2712 usbcore.blinkenlights=
2713 [USB] Set to cycle leds on hubs (default 0 = off).
2714
2715 usbcore.old_scheme_first=
2716 [USB] Start with the old device initialization
2717 scheme (default 0 = off).
2718
2719 usbcore.use_both_schemes=
2720 [USB] Try the other device initialization scheme
2721 if the first one fails (default 1 = enabled).
2722
2723 usbcore.initial_descriptor_timeout=
2724 [USB] Specifies timeout for the initial 64-byte
2725 USB_REQ_GET_DESCRIPTOR request in milliseconds
2726 (default 5000 = 5.0 seconds).
2727
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728 usbhid.mousepoll=
2729 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002730
Alan Sternd4f373e2008-11-10 14:07:45 -05002731 usb-storage.delay_use=
2732 [UMS] The delay in seconds before a new device is
2733 scanned for Logical Units (default 5).
2734
2735 usb-storage.quirks=
2736 [UMS] A list of quirks entries to supplement or
2737 override the built-in unusual_devs list. List
2738 entries are separated by commas. Each entry has
2739 the form VID:PID:Flags where VID and PID are Vendor
2740 and Product ID values (4-digit hex numbers) and
2741 Flags is a set of characters, each corresponding
2742 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002743 a = SANE_SENSE (collect more than 18 bytes
2744 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002745 b = BAD_SENSE (don't collect more than 18
2746 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002747 c = FIX_CAPACITY (decrease the reported
2748 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002749 h = CAPACITY_HEURISTICS (decrease the
2750 reported device capacity by one
2751 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002752 i = IGNORE_DEVICE (don't bind to this
2753 device);
2754 l = NOT_LOCKABLE (don't try to lock and
2755 unlock ejectable media);
2756 m = MAX_SECTORS_64 (don't transfer more
2757 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002758 o = CAPACITY_OK (accept the capacity
2759 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002760 r = IGNORE_RESIDUE (the device reports
2761 bogus residue values);
2762 s = SINGLE_LUN (the device has only one
2763 Logical Unit);
2764 w = NO_WP_DETECT (don't test whether the
2765 medium is write-protected).
2766 Example: quirks=0419:aaf5:rl,0421:0433:rc
2767
Ian Campbell14315592010-02-17 10:38:10 +00002768 userpte=
2769 [X86] Flags controlling user PTE allocations.
2770
2771 nohigh = do not allocate PTE pages in
2772 HIGHMEM regardless of setting
2773 of CONFIG_HIGHPTE.
2774
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302775 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002776 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002777 vdso=1: enable VDSO (default)
2778 vdso=0: disable VDSO mapping
2779
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302780 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002781 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2782 vdso32=1: enable 32-bit VDSO (default)
2783 vdso32=0: disable 32-bit VDSO mapping
2784
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002785 vector= [IA-64,SMP]
2786 vector=percpu: enable percpu vector domain
2787
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788 video= [FB] Frame buffer configuration
2789 See Documentation/fb/modedb.txt.
2790
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002791 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002792 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002793 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002794 Use vga=ask for menu.
2795 This is actually a boot loader parameter; the value is
2796 passed to the kernel using a special protocol.
2797
Randy Dunlapa9913042005-10-23 12:57:11 -07002798 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799 size of <nn>. This can be used to increase the
2800 minimum size (128MB on x86). It can also be used to
2801 decrease the size and leave more room for directly
2802 mapped kernel RAM.
2803
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002804 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2805 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002806
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002807 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2808 Format: <command>
2809
2810 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2811 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002812
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002813 vt.cur_default= [VT] Default cursor shape.
2814 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2815 the parameters of the <Esc>[?A;B;Cc escape sequence;
2816 see VGA-softcursor.txt. Default: 2 = underline.
2817
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002818 vt.default_blu= [VT]
2819 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2820 Change the default blue palette of the console.
2821 This is a 16-member array composed of values
2822 ranging from 0-255.
2823
2824 vt.default_grn= [VT]
2825 Format: <green0>,<green1>,<green2>,...,<green15>
2826 Change the default green palette of the console.
2827 This is a 16-member array composed of values
2828 ranging from 0-255.
2829
2830 vt.default_red= [VT]
2831 Format: <red0>,<red1>,<red2>,...,<red15>
2832 Change the default red palette of the console.
2833 This is a 16-member array composed of values
2834 ranging from 0-255.
2835
2836 vt.default_utf8=
2837 [VT]
2838 Format=<0|1>
2839 Set system-wide default UTF-8 mode for all tty's.
2840 Default is 1, i.e. UTF-8 mode is enabled for all
2841 newly opened terminals.
2842
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002843 vt.global_cursor_default=
2844 [VT]
2845 Format=<-1|0|1>
2846 Set system-wide default for whether a cursor
2847 is shown on new VTs. Default is -1,
2848 i.e. cursors will be created by default unless
2849 overridden by individual drivers. 0 will hide
2850 cursors, 1 will display them.
2851
Linus Torvalds1da177e2005-04-16 15:20:36 -07002852 waveartist= [HW,OSS]
2853 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002854
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855 wd33c93= [HW,SCSI]
2856 See header of drivers/scsi/wd33c93.c.
2857
2858 wd7000= [HW,SCSI]
2859 See header of drivers/scsi/wd7000.c.
2860
2861 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002862 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002864 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2865 default x2apic cluster mode on platforms
2866 supporting x2apic.
2867
Jacob Panbb24c472009-09-02 07:37:17 -07002868 x86_mrst_timer= [X86-32,APBT]
2869 Choose timer option for x86 Moorestown MID platform.
2870 Two valid options are apbt timer only and lapic timer
2871 plus one apbt timer for broadcast timer.
2872 x86_mrst_timer=apbt_only | lapic_and_apbt
2873
Linus Torvalds1da177e2005-04-16 15:20:36 -07002874 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2875 xd_geo= See header of drivers/block/xd.c.
2876
2877 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002878 Format:
2879 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002880
Randy Dunlapa9913042005-10-23 12:57:11 -07002881______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882
2883TODO:
2884
2885 Add documentation for ALSA options.
2886 Add more DRM drivers.