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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100118 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120In addition, the following text indicates that the option:
121
122 BUGS= Relates to possible processor bugs on the said processor.
123 KNL Is a kernel start-up parameter.
124 BOOT Is a boot loader parameter.
125
126Parameters denoted with BOOT are actually interpreted by the boot
127loader, and have no meaning to the kernel directly.
128Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500129need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Karsten Weiss55588702007-02-13 13:26:21 +0100131There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700132See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
135a trailing = on the name of any parameter states that that parameter will
136be entered as an environment variable, whereas its absence indicates that
137it will appear as a kernel argument readable via /proc/cmdline by programs
138running once the system is up.
139
jens m. noedler9c4751f2006-09-29 02:00:27 -0700140The number of kernel parameters is not limited, but the length of the
141complete command line (parameters including spaces etc.) is limited to
142a fixed number of characters. This limit depends on the architecture
143and is between 256 and 4096 characters. It is defined in the file
144./include/asm/setup.h as COMMAND_LINE_SIZE.
145
146
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530147 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800148 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500149 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 force -- enable ACPI if default was off
151 off -- disable ACPI if default was on
152 noirq -- do not use ACPI for IRQ routing
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700296
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700297 agp= [AGP]
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 aha152x= [HW,SCSI]
304 See Documentation/scsi/aha152x.txt.
305
306 aha1542= [HW,SCSI]
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
308
309 aic7xxx= [HW,SCSI]
310 See Documentation/scsi/aic7xxx.txt.
311
312 aic79xx= [HW,SCSI]
313 See Documentation/scsi/aic79xx.txt.
314
Russell Kingd944d542010-02-20 16:13:29 +0000315 alignment= [KNL,ARM]
316 Allow the default userspace alignment fault handler
317 behaviour to be specified. Bit 0 enables warnings,
318 bit 1 enables fixups, and bit 2 sends a segfault.
319
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200320 amd_iommu= [HW,X86-84]
321 Pass parameters to the AMD IOMMU driver in the system.
322 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900323 fullflush - enable flushing of IO/TLB entries when
324 they are unmapped. Otherwise they are
325 flushed before they will be reused, which
326 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200327 off - do not initialize any AMD IOMMU found in
328 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900329
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 amijoy.map= [HW,JOY] Amiga joystick support
331 Map of devices attached to JOY0DAT and JOY1DAT
332 Format: <a>,<b>
333 See also Documentation/kernel/input/joystick.txt
334
335 analog.map= [HW,JOY] Analog joystick and gamepad support
336 Specifies type or capabilities of an analog joystick
337 connected to one of 16 gameports
338 Format: <type1>,<type2>,..<type16>
339
Randy Dunlapa9913042005-10-23 12:57:11 -0700340 apc= [HW,SPARC]
341 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 Format: noidle
343 Disable APC CPU standby support. SPARCstation-Fox does
344 not play well with APC CPU idle - disable it if you have
345 APC and your system crashes randomly.
346
Randy Dunlapca1eda22009-05-06 16:02:58 -0700347 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700348 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 Format: { quiet (default) | verbose | debug }
350 Change the amount of debugging information output
351 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700352
Brian Haleyb0f83b22010-02-04 13:36:50 -0800353 autoconf= [IPV6]
354 See Documentation/networking/ipv6.txt.
355
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400356 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
357 Limit apic dumping. The parameter defines the maximal
358 number of local apics being dumped. Also it is possible
359 to set it to "all" by meaning -- no limit here.
360 Format: { 1 (default) | 2 | ... | all }.
361 The parameter valid if only apic=debug or
362 apic=verbose is specified.
363 Example: apic=debug show_lapic=all
364
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700366 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
369 Format: <io>,<irq>,<nodeID>
370
371 ataflop= [HW,M68k]
372
373 atarimouse= [HW,MOUSE] Atari Mouse
374
375 atascsi= [HW,SCSI] Atari SCSI
376
377 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
378 EzKey and similar keyboards
379
380 atkbd.reset= [HW] Reset keyboard during initialization
381
Randy Dunlapa9913042005-10-23 12:57:11 -0700382 atkbd.set= [HW] Select keyboard code set
383 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
385 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
386 keyboards
387
388 atkbd.softraw= [HW] Choose between synthetic and real raw mode
389 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700390
391 atkbd.softrepeat= [HW]
392 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393
394 autotest [IA64]
395
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 baycom_epp= [HW,AX25]
397 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
400 Format: <io>,<mode>
401 See header of drivers/net/hamradio/baycom_par.c.
402
Randy Dunlapa9913042005-10-23 12:57:11 -0700403 baycom_ser_fdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 Format: <io>,<irq>,<mode>[,<baud>]
406 See header of drivers/net/hamradio/baycom_ser_fdx.c.
407
Randy Dunlapa9913042005-10-23 12:57:11 -0700408 baycom_ser_hdx= [HW,AX25]
409 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 Format: <io>,<irq>,<mode>
411 See header of drivers/net/hamradio/baycom_ser_hdx.c.
412
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700413 boot_delay= Milliseconds to delay each printk during boot.
414 Values larger than 10 seconds (10000) are changed to
415 no delay (0).
416 Format: integer
417
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700418 bootmem_debug [KNL] Enable bootmem allocator debug messages.
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700421 bttv.radio= Most important insmod options are available as
422 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
424 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
425
426 BusLogic= [HW,SCSI]
427 See drivers/scsi/BusLogic.c, comment before function
428 BusLogic_ParseDriverOptions().
429
430 c101= [NET] Moxa C101 synchronous serial card
431
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700432 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 Sometimes CPU hardware bugs make them report the cache
434 size incorrectly. The kernel will attempt work arounds
435 to fix known problems, but for some CPUs it is not
436 possible to determine what the correct size should be.
437 This option provides an override for these situations.
438
James Morris20510f22007-10-16 23:31:32 -0700439 capability.disable=
440 [SECURITY] Disable capabilities. This would normally
441 be used only if an alternative security model is to be
442 configured. Potentially dangerous and should only be
443 used if you are entirely sure of the consequences.
444
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100445 ccw_timeout_log [S390]
446 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447
Paul Menage8bab8dd2008-04-04 14:29:57 -0700448 cgroup_disable= [KNL] Disable a particular controller
449 Format: {name of the controller(s) to disable}
450 {Currently supported controllers - "memory"}
451
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 checkreqprot [SELINUX] Set initial checkreqprot flag value.
453 Format: { "0" | "1" }
454 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700455 0 -- check protection applied by kernel (includes
456 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 1 -- check protection requested by application.
458 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700459 Value can be changed at runtime via
460 /selinux/checkreqprot.
461
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100462 cio_ignore= [S390]
463 See Documentation/s390/CommonIO for details.
464
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700465 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700466 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200467 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700468 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200469 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 Format: { pit | tsc | cyclone | pmtmr }
471
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700472 clocksource= [GENERIC_TIME] Override the default clocksource
473 Format: <string>
474 Override the default clocksource and use the clocksource
475 with the name specified.
476 Some clocksource names to choose from, depending on
477 the platform:
478 [all] jiffies (this is the base, fallback clocksource)
479 [ACPI] acpi_pm
480 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
481 pxa_timer,timer3,32k_counter,timer0_1
482 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700483 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700484 scx200_hrt on Geode; cyclone on IBM x440
485 [MIPS] MIPS
486 [PARISC] cr16
487 [S390] tod
488 [SH] SuperH
489 [SPARC64] tick
490 [X86-64] hpet,tsc
491
Andi Kleenac72e782008-01-30 13:33:21 +0100492 clearcpuid=BITNUM [X86]
493 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800494 arch/x86/include/asm/cpufeature.h for the valid bit
495 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100496 stable over kernel options, but the vendor specific
497 ones should be.
498 Also note that user programs calling CPUID directly
499 or using the feature without checking anything
500 will still see it. This just prevents it from
501 being used by the kernel or shown in /proc/cpuinfo.
502 Also note the kernel might malfunction if you disable
503 some critical bits.
504
Robert Jennings14f966e2009-04-15 05:55:32 +0000505 cmo_free_hint= [PPC] Format: { yes | no }
506 Specify whether pages are marked as being inactive
507 when they are freed. This is used in CMO environments
508 to determine OS memory pressure for page stealing by
509 a hypervisor.
510 Default: yes
511
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530512 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100513 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100514 Range: 0 - 8192
515 Default: 64
516
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700518 Format:
519 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520
521 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
522 Format: <io>[,<irq>]
523
Randy Dunlapa9913042005-10-23 12:57:11 -0700524 com90xx= [HW,NET]
525 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 Format: <io>[,<irq>[,<memstart>]]
527
528 condev= [HW,S390] console device
529 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700530
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 console= [KNL] Output console device and options.
532
533 tty<n> Use the virtual console device <n>.
534
535 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800536 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800538 the form "bbbbpnf", where "bbbb" is the baud rate,
539 "p" is parity ("n", "o", or "e"), "n" is number of
540 bits, and "f" is flow control ("r" for RTS or
541 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800543 See Documentation/serial-console.txt for more
544 information. See
545 Documentation/networking/netconsole.txt for an
546 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700548 uart[8250],io,<addr>[,options]
549 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 Start an early, polled-mode console on the 8250/16550
551 UART at the specified I/O port or MMIO address,
552 switching to the matching ttyS device later. The
553 options are the same as for ttyS, above.
554
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700555 If the device connected to the port is not a TTY but a braille
556 device, prepend "brl," before the device type, for instance
557 console=brl,ttyS0
558 For now, only VisioBraille is supported.
559
Daniel Mackf324edc2009-06-16 15:33:52 -0700560 consoleblank= [KNL] The console blank (screen saver) timeout in
561 seconds. Defaults to 10*60 = 10mins. A value of 0
562 disables the blank timer.
563
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800564 coredump_filter=
565 [KNL] Change the default value for
566 /proc/<pid>/coredump_filter.
567 See also Documentation/filesystems/proc.txt.
568
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700570 Format:
571 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700573 crashkernel=nn[KMG]@ss[KMG]
574 [KNL] Reserve a chunk of physical memory to
575 hold a kernel to switch to with kexec on panic.
576
Bernhard Wallefb391592007-10-18 23:41:02 -0700577 crashkernel=range1:size1[,range2:size2,...][@offset]
578 [KNL] Same as above, but depends on the memory
579 in the running system. The syntax of range is
580 start-[end] where start and end are both
581 a memory unit (amount[KMG]). See also
582 Documentation/kdump/kdump.txt for a example.
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 cs89x0_dma= [HW,NET]
585 Format: <dma>
586
587 cs89x0_media= [HW,NET]
588 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700589
Randy Dunlapa9913042005-10-23 12:57:11 -0700590 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 See header of drivers/s390/block/dasd_devmap.c.
592
593 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
594 (one device per port)
595 Format: <port#>,<type>
596 See also Documentation/input/joystick-parport.txt
597
598 debug [KNL] Enable kernel debugging (events log level).
599
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700600 debug_locks_verbose=
601 [KNL] verbose self-tests
602 Format=<0|1>
603 Print debugging info while doing the locking API
604 self-tests.
605 We default to 0 (no extra messages), setting it to
606 1 will print _a lot_ more information - normally
607 only useful to kernel developers.
608
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700609 debug_objects [KNL] Enable object debugging
610
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500611 no_debug_objects
612 [KNL] Disable object debugging
613
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200614 debugpat [X86] Enable PAT debugging
615
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200616 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 Format: <area>[,<node>]
618 See also Documentation/networking/decnet.txt.
619
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700620 default_hugepagesz=
621 [same as hugepagesz=] The size of the default
622 HugeTLB page size. This is the size represented by
623 the legacy /proc/ hugepages APIs, used for SHM, and
624 default size when mounting hugetlbfs filesystems.
625 Defaults to the default architecture's huge page size
626 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700627
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 dhash_entries= [KNL]
629 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700630
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 digi= [HW,SERIAL]
632 IO parameters + enable/disable command.
633
634 digiepca= [HW,SERIAL]
635 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000636 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
Brian Haleyb0f83b22010-02-04 13:36:50 -0800638 disable= [IPV6]
639 See Documentation/networking/ipv6.txt.
640
641 disable_ipv6= [IPV6]
642 See Documentation/networking/ipv6.txt.
643
Yinghai Lu95ffa242008-04-29 03:52:33 -0700644 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700645 The kernel tries to adjust MTRR layout from continuous
646 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700647 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700648
Yinghai Lu093af8d2008-01-30 13:33:32 +0100649 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100650 By default the kernel will trim any uncacheable
651 memory out of your available memory pool based on
652 MTRR settings. This parameter disables that behavior,
653 possibly causing your machine to run very slowly.
654
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530655 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700656 Disable PIN 1 of APIC timer
657 Can be useful to work around chipset bugs.
658
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 dmasound= [HW,OSS] Sound subsystem buffers
660
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700661 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
662 this option disables the debugging code at boot.
663
664 dma_debug_entries=<number>
665 This option allows to tune the number of preallocated
666 entries for DMA-API debugging code. One entry is
667 required per DMA-API allocation. Use this if the
668 DMA-API debugging code disables itself because the
669 architectural default is too low.
670
Joerg Roedel1745de52009-05-22 21:49:51 +0200671 dma_debug_driver=<driver_name>
672 With this option the DMA-API debugging driver
673 filter feature can be enabled at boot time. Just
674 pass the driver to filter for as the parameter.
675 The filter can be disabled or changed to another
676 driver later using sysfs.
677
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 dscc4.setup= [NET]
679
680 dtc3181e= [HW,SCSI]
681
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700682 dynamic_printk Enables pr_debug()/dev_dbg() calls if
683 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
684 These can also be switched on/off via
685 <debugfs>/dynamic_printk/modules
686
687 earlycon= [KNL] Output early console device and options.
688 uart[8250],io,<addr>[,options]
689 uart[8250],mmio,<addr>[,options]
690 Start an early, polled-mode console on the 8250/16550
691 UART at the specified I/O port or MMIO address.
692 The options are the same as for ttyS, above.
693
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530694 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 earlyprintk=vga
696 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500697 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500698 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699
Randy Dunlapa9913042005-10-23 12:57:11 -0700700 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 takes over.
702
Yinghai Lu5c059172008-07-24 17:29:40 -0700703 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704
705 Currently only ttyS0 and ttyS1 are supported.
706
707 Interaction with the standard serial driver is not
708 very good.
709
710 The VGA output is eventually overwritten by the real
711 console.
712
Jason Wessel97311912010-05-20 21:04:30 -0500713 ekgdboc= [X86,KGDB] Allow early kernel console debugging
714 ekgdboc=kbd
715
716 This is desgined to be used in conjunction with
717 the boot argument: earlyprintk=vga
718
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 eata= [HW,SCSI]
720
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700722 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 eisa_irq_edge= [PARISC,HW]
725 See header of drivers/parisc/eisa.c.
726
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700727 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700729 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730
731 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800732 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700733 See Documentation/block/as-iosched.txt and
734 Documentation/block/deadline-iosched.txt for details.
735
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530736 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700737 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800738 image elf header. Generally kexec loader will
739 pass this option to capture kernel.
740 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700742 enable_mtrr_cleanup [X86]
743 The kernel tries to adjust MTRR layout from continuous
744 to discrete, to make X server driver able to add WB
745 entry later. This parameter enables that.
746
Randy Dunlapca1eda22009-05-06 16:02:58 -0700747 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700748 Enable PIN 1 of APIC timer
749 Can be useful to work around chipset bugs
750 (in particular on some ATI chipsets).
751 The kernel tries to set a reasonable default.
752
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 enforcing [SELINUX] Set initial enforcing status.
754 Format: {"0" | "1"}
755 See security/selinux/Kconfig help text.
756 0 -- permissive (log only, no denials).
757 1 -- enforcing (deny and log).
758 Default value is 0.
759 Value can be changed at runtime via /selinux/enforce.
760
Huang Yinga08f82d2010-05-18 14:35:21 +0800761 erst_disable [ACPI]
762 Disable Error Record Serialization Table (ERST)
763 support.
764
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 ether= [HW,NET] Ethernet cards parameters
766 This option is obsoleted by the "netdev=" option, which
767 has equivalent usage. See its documentation for details.
768
Akinobu Mitade1ba092006-12-08 02:39:42 -0800769 failslab=
770 fail_page_alloc=
771 fail_make_request=[KNL]
772 General fault injection mechanism.
773 Format: <interval>,<probability>,<space>,<times>
774 See also /Documentation/fault-injection/.
775
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 fd_mcs= [HW,SCSI]
777 See header of drivers/scsi/fd_mcs.c.
778
779 fdomain= [HW,SCSI]
780 See header of drivers/scsi/fdomain.c.
781
782 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000783 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
Alex Chiangf13ae302008-05-08 14:03:23 -0600785 force_pal_cache_flush
786 [IA-64] Avoid check_sal_cache_flush which may hang on
787 buggy SAL_CACHE_FLUSH implementations. Using this
788 parameter will force ia64_sal_cache_flush to call
789 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
790
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100791 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400792 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100793 as early as possible in order to facilitate early
794 boot debugging.
795
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200796 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400797 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200798 If no parameter is passed, ftrace will dump
799 buffers of all CPUs, but if you pass orig_cpu, it will
800 dump only the buffer of the CPU that triggered the
801 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400802
803 ftrace_filter=[function-list]
804 [FTRACE] Limit the functions traced by the function
805 tracer at boot up. function-list is a comma separated
806 list of functions. This list can be changed at run
807 time by the set_ftrace_filter file in the debugfs
808 tracing directory.
809
810 ftrace_notrace=[function-list]
811 [FTRACE] Do not trace the functions specified in
812 function-list. This list can be changed at run time
813 by the set_ftrace_notrace file in the debugfs
814 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100815
Stefan Assmann369bc182009-10-12 22:17:21 +0200816 ftrace_graph_filter=[function-list]
817 [FTRACE] Limit the top level callers functions traced
818 by the function graph tracer at boot up.
819 function-list is a comma separated list of functions
820 that can be changed at run time by the
821 set_graph_function file in the debugfs tracing directory.
822
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 gamecon.map[2|3]=
824 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
825 support via parallel port (up to 5 devices per port)
826 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
827 See also Documentation/input/joystick-parport.txt
828
829 gamma= [HW,DRM]
830
Yinghai Luaaf23042008-01-30 13:33:09 +0100831 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
832 Format: off | on
833 default: on
834
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700835 gcov_persist= [GCOV] When non-zero (default), profiling data for
836 kernel modules is saved and remains accessible via
837 debugfs, even when the module is unloaded/reloaded.
838 When zero, profiling data is discarded and associated
839 debugfs files are removed at module unload time.
840
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 gdth= [HW,SCSI]
842 See header of drivers/scsi/gdth.c.
843
844 gpt [EFI] Forces disk with valid GPT signature but
845 invalid Protective MBR to be treated as GPT.
846
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 gvp11= [HW,SCSI]
848
849 hashdist= [KNL,NUMA] Large hashes allocated during boot
850 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700851 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700852 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853
854 hcl= [IA-64] SGI's Hardware Graph compatibility layer
855
856 hd= [EIDE] (E)IDE hard drive subsystem geometry
857 Format: <cyl>,<head>,<sect>
858
Huang Yingea8c0712010-05-18 14:35:15 +0800859 hest_disable [ACPI]
860 Disable Hardware Error Source Table (HEST) support;
861 corresponding firmware-first mode error processing
862 logic will be disabled.
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
865 size of <nn>. This works even on boxes that have no
866 highmem otherwise. This also works to reduce highmem
867 size on bigger boxes.
868
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800869 highres= [KNL] Enable/disable high resolution timer mode.
870 Valid parameters: "on", "off"
871 Default: "on"
872
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 hisax= [HW,ISDN]
874 See Documentation/isdn/README.HiSax.
875
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700876 hlt [BUGS=ARM,SH]
877
878 hpet= [X86-32,HPET] option to control HPET usage
879 Format: { enable (default) | disable | force |
880 verbose }
881 disable: disable HPET and use PIT instead
882 force: allow force enabled of undocumented chips (ICH4,
883 VIA, nVidia)
884 verbose: show contents of HPET registers during setup
885
Andi Kleenb4718e62008-07-23 21:27:51 -0700886 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
887 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700888 On x86-64 and powerpc, this option can be specified
889 multiple times interleaved with hugepages= to reserve
890 huge pages of different sizes. Valid pages sizes on
891 x86-64 are 2M (when the CPU supports "pse") and 1G
892 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700893 Note that 1GB pages can only be allocated at boot time
894 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900895
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100896 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
897 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100898 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
899 If specified, z/VM IUCV HVC accepts connections
900 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100901
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700902 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700903 or register an additional I2C bus that is not
904 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700905 Format:
906 <bus_id>,<clkrate>
907
Jiri Kosina36d95732008-10-06 02:51:09 -0400908 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200910 i8042.dumbkbd [HW] Pretend that controller can only read data from
911 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 (Don't attempt to blink the leds)
913 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500914 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400915 i8042.noloop [HW] Disable the AUX Loopback command while probing
916 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 i8042.nomux [HW] Don't check presence of an active multiplexing
918 controller
919 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
920 controllers
921 i8042.panicblink=
922 [HW] Frequency with which keyboard LEDs should blink
923 when kernel panics (default is 0.5 sec)
924 i8042.reset [HW] Reset the controller during init and cleanup
925 i8042.unlock [HW] Unlock (ignore) the keylock
926
927 i810= [HW,DRM]
928
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700929 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
930 indicates that the driver is running on unsupported
931 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
933 does not match list of supported models.
934 i8k.power_status
935 [HW] Report power status in /proc/i8k
936 (disabled by default)
937 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
938 capability is set.
939
940 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
941 See Documentation/mca.txt.
942
943 icn= [HW,ISDN]
944 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
945
David Fries0af80c02009-02-25 20:28:21 +0100946 ide-core.nodma= [HW] (E)IDE subsystem
947 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200948 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
949 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100950 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700952 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
953 Claim all unknown PCI IDE storage controllers.
954
Andi Kleenf039b752007-05-02 19:27:12 +0200955 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800956 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
957 Poll forces a polling idle loop that can slightly
958 improve the performance of waking up a idle CPU, but
959 will use a lot of power and make the system run hot.
960 Not recommended.
961 idle=mwait: On systems which support MONITOR/MWAIT but
962 the kernel chose to not use it because it doesn't save
963 as much power as a normal idle loop, use the
964 MONITOR/MWAIT idle loop anyways. Performance should be
965 the same as idle=poll.
966 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800967 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800968 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700969
Ingo Molnar792908222006-12-06 20:40:51 -0800970 ignore_loglevel [KNL]
971 Ignore loglevel setting - this will print /all/
972 kernel messages to the console. Useful for debugging.
973
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 ihash_entries= [KNL]
975 Set number of hash buckets for inode cache.
976
Mimi Zohar3323eec92009-02-04 09:06:58 -0500977 ima_audit= [IMA]
978 Format: { "0" | "1" }
979 0 -- integrity auditing messages. (Default)
980 1 -- enable informational integrity auditing messages.
981
982 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700983 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500984 default: "sha1"
985
Eric Paris5789ba32009-05-21 15:47:06 -0400986 ima_tcb [IMA]
987 Load a policy which meets the needs of the Trusted
988 Computing Base. This means IMA will measure all
989 programs exec'd, files mmap'd for exec, and all files
990 opened for read by uid=0.
991
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 in2000= [HW,SCSI]
993 See header of drivers/scsi/in2000.c.
994
995 init= [KNL]
996 Format: <full_path>
997 Run specified binary instead of /sbin/init as init
998 process.
999
1000 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1001 for working out where the kernel is dying during
1002 startup.
1003
1004 initrd= [BOOT] Specify the location of the initial ramdisk
1005
1006 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1007 Format: <irq>
1008
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001009 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001010 on
1011 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001012 off
1013 Disable intel iommu driver.
1014 igfx_off [Default Off]
1015 By default, gfx is mapped as normal device. If a gfx
1016 device has a dedicated DMAR unit, the DMAR unit is
1017 bypassed by not enabling DMAR with this option. In
1018 this case, gfx device will use physical address for
1019 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001020 forcedac [x86_64]
1021 With this option iommu will not optimize to look
1022 for io virtual address below 32 bit forcing dual
1023 address cycle on pci bus for cards supporting greater
1024 than 32 bit addressing. The default is to look
1025 for translation below 32 bit and if not available
1026 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001027 strict [Default Off]
1028 With this option on every unmap_single operation will
1029 result in a hardware IOTLB flush operation as opposed
1030 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001031
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001032 inttest= [IA64]
1033
1034 iomem= Disable strict checking of access to MMIO memory
1035 strict regions from userspace.
1036 relaxed
1037
1038 iommu= [x86]
1039 off
1040 force
1041 noforce
1042 biomerge
1043 panic
1044 nopanic
1045 merge
1046 nomerge
1047 forcesac
1048 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001049 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001050
1051 io7= [HW] IO7 for Marvel based alpha systems
1052 See comment before marvel_specify_io7 in
1053 arch/alpha/kernel/core_marvel.c.
1054
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301055 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001056 0x80
1057 Standard port 0x80 based delay
1058 0xed
1059 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001060 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001061 Simple two microseconds delay
1062 none
1063 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001064
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001066 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067
1068 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001069 See comment before ip2_setup() in
1070 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071
1072 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1073 See header of drivers/scsi/ips.c.
1074
Alan Cox200803d2005-06-28 20:45:18 -07001075 irqfixup [HW]
1076 When an interrupt is not handled search all handlers
1077 for it. Intended to get systems with badly broken
1078 firmware running.
1079
1080 irqpoll [HW]
1081 When an interrupt is not handled search all handlers
1082 for it. Also check all handlers each timer
1083 interrupt. Intended to get systems with badly broken
1084 firmware running.
1085
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001087 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088
1089 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001090 Format:
1091 <cpu number>,...,<cpu number>
1092 or
Li Zefanb225d442008-11-06 12:53:39 -08001093 <cpu number>-<cpu number>
1094 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001095 or a mixture
1096 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001097
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 This option can be used to specify one or more CPUs
1099 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001100 algorithms. You can move a process onto or off an
1101 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 <cpu number> begins at 0 and the maximum value is
1103 "number of CPUs in system - 1".
1104
1105 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001106 alternative -- manually setting the CPU mask of all
1107 tasks in the system -- can cause problems and
1108 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109
Randy Dunlapa9913042005-10-23 12:57:11 -07001110 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111
1112 js= [HW,JOY] Analog joystick
1113 See Documentation/input/joystick.txt.
1114
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001115 keepinitrd [HW,ARM]
1116
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301117 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001118 specifies the amount of memory usable by the kernel
1119 for non-movable allocations. The requested amount is
1120 spread evenly throughout all nodes in the system. The
1121 remaining memory in each node is used for Movable
1122 pages. In the event, a node is too small to have both
1123 kernelcore and Movable pages, kernelcore pages will
1124 take priority and other nodes will have a larger number
1125 of kernelcore pages. The Movable zone is used for the
1126 allocation of pages that may be reclaimed or moved
1127 by the page migration subsystem. This means that
1128 HugeTLB pages may not be allocated from this zone.
1129 Note that allocations like PTEs-from-HighMem still
1130 use the HighMem zone if it exists, and the Normal
1131 zone if it does not.
1132
Jason Wessel4fe1da42010-05-20 21:04:31 -05001133 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1134 Format: <Controller#>[,poll interval]
1135 The controller # is the number of the ehci usb debug
1136 port as it is probed via PCI. The poll interval is
1137 optional and is the number seconds in between
1138 each poll cycle to the debug port in case you need
1139 the functionality for interrupting the kernel with
1140 gdb or control-c on the dbgp connection. When
1141 not using this parameter you use sysrq-g to break into
1142 the kernel debugger.
1143
Jason Wessel84c08fd2010-05-20 21:04:24 -05001144 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001145 Requires a tty driver that supports console polling,
1146 or a supported polling keyboard driver (non-usb).
1147 Serial only format: <serial_device>[,baud]
1148 keyboard only format: kbd
1149 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001150
Jason Wessel84c08fd2010-05-20 21:04:24 -05001151 kgdbwait [KGDB] Stop kernel execution and enter the
1152 kernel debugger at the earliest opportunity.
1153
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001154 kmac= [MIPS] korina ethernet MAC address.
1155 Configure the RouterBoard 532 series on-chip
1156 Ethernet adapter MAC address.
1157
Catalin Marinas04f70332009-06-11 13:22:39 +01001158 kmemleak= [KNL] Boot-time kmemleak enable/disable
1159 Valid arguments: on, off
1160 Default: on
1161
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301162 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001163 in oops dumps.
1164
Andre Przywarafef07aa2009-07-10 14:20:35 +02001165 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1166 Default is 0 (don't ignore, but inject #GP)
1167
1168 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1169 Default is 1 (enabled)
1170
1171 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1172 Default is 0 (off)
1173
1174 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1175 for all guests.
1176 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1177
1178 kvm-intel.bypass_guest_pf=
1179 [KVM,Intel] Disables bypassing of guest page faults
1180 on Intel chips. Default is 1 (enabled)
1181
1182 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1183 (virtualized MMU) support on capable Intel chips.
1184 Default is 1 (enabled)
1185
1186 kvm-intel.emulate_invalid_guest_state=
1187 [KVM,Intel] Enable emulation of invalid guest states
1188 Default is 0 (disabled)
1189
1190 kvm-intel.flexpriority=
1191 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1192 Default is 1 (enabled)
1193
1194 kvm-intel.unrestricted_guest=
1195 [KVM,Intel] Disable unrestricted guest feature
1196 (virtualized real and unpaged mode) on capable
1197 Intel chips. Default is 1 (enabled)
1198
1199 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1200 feature (tagged TLBs) on capable Intel chips.
1201 Default is 1 (enabled)
1202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203 l2cr= [PPC]
1204
Robert Brosea78bfbf2008-03-29 07:20:23 +11001205 l3cr= [PPC]
1206
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001207 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001208 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301210 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001211 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001212
FD Camifcb71f62008-01-06 19:08:56 +01001213 libata.dma= [LIBATA] DMA control
1214 libata.dma=0 Disable all PATA and SATA DMA
1215 libata.dma=1 PATA and SATA Disk DMA only
1216 libata.dma=2 ATAPI (CDROM) DMA only
1217 libata.dma=4 Compact Flash DMA only
1218 Combinations also work, so libata.dma=3 enables DMA
1219 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001220
1221 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1222 libata.ignore_hpa=0 keep BIOS limits (default)
1223 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001224
Dave Jones78e70c22007-09-27 11:50:13 -04001225 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1226 when set.
1227 Format: <int>
1228
Tejun Heo33267322008-02-13 09:15:09 +09001229 libata.force= [LIBATA] Force configurations. The format is comma
1230 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001231 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001232 matching port, link or device. Basically, it matches
1233 the ATA ID string printed on console by libata. If
1234 the whole ID part is omitted, the last PORT and DEVICE
1235 values are used. If ID hasn't been specified yet, the
1236 configuration applies to all ports, links and devices.
1237
1238 If only DEVICE is omitted, the parameter applies to
1239 the port and all links and devices behind it. DEVICE
1240 number of 0 either selects the first device or the
1241 first fan-out link behind PMP device. It does not
1242 select the host link. DEVICE number of 15 selects the
1243 host link and device attached to it.
1244
1245 The VAL specifies the configuration to force. As long
1246 as there's no ambiguity shortcut notation is allowed.
1247 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1248 The following configurations can be forced.
1249
1250 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1251 Any ID with matching PORT is used.
1252
1253 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1254
1255 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1256 udma[/][16,25,33,44,66,100,133] notation is also
1257 allowed.
1258
1259 * [no]ncq: Turn on or off NCQ.
1260
Tejun Heo05944bd2008-08-13 20:19:09 +09001261 * nohrst, nosrst, norst: suppress hard, soft
1262 and both resets.
1263
Tejun Heo43c9c592010-05-23 12:59:11 +02001264 * dump_id: dump IDENTIFY data.
1265
Tejun Heo33267322008-02-13 09:15:09 +09001266 If there are multiple matching configurations changing
1267 the same attribute, the last one is used.
1268
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001269 lmb=debug [KNL] Enable lmb debug messages.
1270
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001272 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001274 lockd.nlm_grace_period=P [NFS] Assign grace period.
1275 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001277 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1278 Format: <integer>
1279
1280 lockd.nlm_timeout=T [NFS] Assign timeout value.
1281 Format: <integer>
1282
1283 lockd.nlm_udpport=M [NFS] Assign UDP port.
1284 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
1286 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1287 Format: <irq>
1288
1289 loglevel= All Kernel Messages with a loglevel smaller than the
1290 console loglevel will be printed to the console. It can
1291 also be changed with klogd or other programs. The
1292 loglevels are defined as follows:
1293
1294 0 (KERN_EMERG) system is unusable
1295 1 (KERN_ALERT) action must be taken immediately
1296 2 (KERN_CRIT) critical conditions
1297 3 (KERN_ERR) error conditions
1298 4 (KERN_WARNING) warning conditions
1299 5 (KERN_NOTICE) normal but significant condition
1300 6 (KERN_INFO) informational
1301 7 (KERN_DEBUG) debug-level messages
1302
1303 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001304 Format: { n | nk | nM }
1305 n must be a power of two. The default size
1306 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307
Randy Dunlapaccaa242007-10-16 01:29:37 -07001308 logo.nologo [FB] Disables display of the built-in Linux logo.
1309 This may be used to provide more screen space for
1310 kernel log messages and is useful when debugging
1311 kernel boot problems.
1312
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 lp=0 [LP] Specify parallel ports to use, e.g,
1314 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1315 lp=reset first parallel port). 'lp=0' disables the
1316 lp=auto printer driver. 'lp=reset' (which can be
1317 specified in addition to the ports) causes
1318 attached printers to be reset. Using
1319 lp=port1,port2,... specifies the parallel ports
1320 to associate lp devices with, starting with
1321 lp0. A port specification may be 'none' to skip
1322 that lp device, or a parport name such as
1323 'parport0'. Specifying 'lp=auto' instead of a
1324 port specification list means that device IDs
1325 from each port should be examined, to see if
1326 an IEEE 1284-compliant printer is attached; if
1327 so, the driver will manage that printer.
1328 See also header of drivers/char/lp.c.
1329
1330 lpj=n [KNL]
1331 Sets loops_per_jiffy to given constant, thus avoiding
1332 time-consuming boot-time autodetection (up to 250 ms per
1333 CPU). 0 enables autodetection (default). To determine
1334 the correct value for your kernel, boot with normal
1335 autodetection and see what value is printed. Note that
1336 on SMP systems the preset will be applied to all CPUs,
1337 which is likely to cause problems if your CPUs need
1338 significantly divergent settings. An incorrect value
1339 will cause delays in the kernel to be wrong, leading to
1340 unpredictable I/O errors and other breakage. Although
1341 unlikely, in the extreme case this might damage your
1342 hardware.
1343
1344 ltpc= [NET]
1345 Format: <io>,<irq>,<dma>
1346
Randy Dunlapa9913042005-10-23 12:57:11 -07001347 mac5380= [HW,SCSI] Format:
1348 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
Randy Dunlapa9913042005-10-23 12:57:11 -07001350 machvec= [IA64] Force the use of a particular machine-vector
1351 (machvec) in a generic kernel.
1352 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
Wu Zhangjin3209e702009-07-02 23:27:12 +08001354 machtype= [Loongson] Share the same kernel image file between different
1355 yeeloong laptop.
1356 Example: machtype=lemote-yeeloong-2f-7inch
1357
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001358 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1359 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360
1361 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001362 should make use of. maxcpus=n : n >= 0 limits the
1363 kernel to using 'n' processors. n=0 is a special case,
1364 it is equivalent to "nosmp", which also disables
1365 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001367 max_loop= [LOOP] Maximum number of loopback devices that can
1368 be mounted
1369 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001370
Randy Dunlapa9913042005-10-23 12:57:11 -07001371 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 Should be between 1 and 2^32-1.
1373
1374 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001375 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 Should be between 1 and 16384.
1377
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 mcatest= [IA-64]
1379
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001380 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381
Uwe Hermann71cced62008-10-20 09:32:21 -07001382 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001383
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 md= [HW] RAID subsystems devices and level
1385 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001386
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 mdacon= [MDA]
1388 Format: <first>,<last>
1389 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001390
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1392 Amount of memory to be used when the kernel is not able
1393 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001394 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 address space collisions. Without memmap= PCI devices
1396 could be placed at addresses belonging to unused RAM.
1397
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001398 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 memory.
1400
Paul Mundt6902aa82008-09-21 17:14:42 +09001401 memchunk=nn[KMG]
1402 [KNL,SH] Allow user to override the default size for
1403 per-device physically contiguous DMA buffers.
1404
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301405 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 E820 memory map, as specified by the user.
1407 Such memmap=exactmap lines can be constructed based on
1408 BIOS output or other requirements. See the memmap=nn@ss
1409 option description.
1410
1411 memmap=nn[KMG]@ss[KMG]
1412 [KNL] Force usage of a specific region of memory
1413 Region of memory to be used, from ss to ss+nn.
1414
1415 memmap=nn[KMG]#ss[KMG]
1416 [KNL,ACPI] Mark specific memory as ACPI data.
1417 Region of memory to be used, from ss to ss+nn.
1418
1419 memmap=nn[KMG]$ss[KMG]
1420 [KNL,ACPI] Mark specific memory as reserved.
1421 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001422 Example: Exclude memory from 0x18690000-0x1869ffff
1423 memmap=64K$0x18690000
1424 or
1425 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001427 memory_corruption_check=0/1 [X86]
1428 Some BIOSes seem to corrupt the first 64k of
1429 memory when doing things like suspend/resume.
1430 Setting this option will scan the memory
1431 looking for corruption. Enabling this will
1432 both detect corruption and prevent the kernel
1433 from using the memory being corrupted.
1434 However, its intended as a diagnostic tool; if
1435 repeatable BIOS-originated corruption always
1436 affects the same memory, you can use memmap=
1437 to prevent the kernel from using that memory.
1438
1439 memory_corruption_check_size=size [X86]
1440 By default it checks for corruption in the low
1441 64k, making this memory unavailable for normal
1442 use. Use this parameter to scan for
1443 corruption in more or less memory.
1444
1445 memory_corruption_check_period=seconds [X86]
1446 By default it checks for corruption every 60
1447 seconds. Use this parameter to check at some
1448 other rate. 0 disables periodic checking.
1449
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001450 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001451 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001452 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001453 Specifies the number of memtest passes to be
1454 performed. Each pass selects another test
1455 pattern from a given set of patterns. Memtest
1456 fills the memory with this pattern, validates
1457 memory contents and reserves bad memory
1458 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 meye.*= [HW] Set MotionEye Camera parameters
1461 See Documentation/video4linux/meye.txt.
1462
Andres Salomon8f368812007-10-12 23:04:06 +02001463 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1464 Multi-Function General Purpose Timers on AMD Geode
1465 platforms.
1466
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001467 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1468 the BIOS has incorrectly applied a workaround. TinyBIOS
1469 version 0.98 is known to be affected, 0.99 fixes the
1470 problem by letting the user disable the workaround.
1471
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 mga= [HW,DRM]
1473
Randy Dunlap1c207f92008-11-19 15:36:16 -08001474 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1475 physical address is ignored.
1476
Michel Pollet39f45d72009-05-20 11:10:31 +01001477 mini2440= [ARM,HW,KNL]
1478 Format:[0..2][b][c][t]
1479 Default: "0tb"
1480 MINI2440 configuration specification:
1481 0 - The attached screen is the 3.5" TFT
1482 1 - The attached screen is the 7" TFT
1483 2 - The VGA Shield is attached (1024x768)
1484 Leaving out the screen size parameter will not load
1485 the TFT driver, and the framebuffer will be left
1486 unconfigured.
1487 b - Enable backlight. The TFT backlight pin will be
1488 linked to the kernel VESA blanking code and a GPIO
1489 LED. This parameter is not necessary when using the
1490 VGA shield.
1491 c - Enable the s3c camera interface.
1492 t - Reserved for enabling touchscreen support. The
1493 touchscreen support is not enabled in the mainstream
1494 kernel as of 2.6.30, a preliminary port can be found
1495 in the "bleeding edge" mini2440 support kernel at
1496 http://repo.or.cz/w/linux-2.6/mini2440.git
1497
Mel Gorman6b74ab92008-07-23 21:26:49 -07001498 mminit_loglevel=
1499 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1500 parameter allows control of the logging verbosity for
1501 the additional memory initialisation checks. A value
1502 of 0 disables mminit logging and a level of 4 will
1503 log everything. Information is printed at KERN_DEBUG
1504 so loglevel=8 may also need to be specified.
1505
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506 mousedev.tap_time=
1507 [MOUSE] Maximum time between finger touching and
1508 leaving touchpad surface for touch to be considered
1509 a tap and be reported as a left button click (for
1510 touchpads working in absolute mode only).
1511 Format: <msecs>
1512 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1513 reporting absolute coordinates, such as tablets
1514 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1515 reporting absolute coordinates, such as tablets
1516
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301517 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001518 is similar to kernelcore except it specifies the
1519 amount of memory used for migratable allocations.
1520 If both kernelcore and movablecore is specified,
1521 then kernelcore will be at *least* the specified
1522 value but may be more. If movablecore on its own
1523 is specified, the administrator must be careful
1524 that the amount of memory usable for all allocations
1525 is not too small.
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 mpu401= [HW,OSS]
1528 Format: <io>,<irq>
1529
1530 MTD_Partition= [MTD]
1531 Format: <name>,<region-number>,<size>,<offset>
1532
Randy Dunlapa9913042005-10-23 12:57:11 -07001533 MTD_Region= [MTD] Format:
1534 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535
1536 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001537 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001539 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1540
1541 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1542
1543 boundary - index of last SLC block on Flex-OneNAND.
1544 The remaining blocks are configured as MLC blocks.
1545 lock - Configure if Flex-OneNAND boundary should be locked.
1546 Once locked, the boundary cannot be changed.
1547 1 indicates lock status, 0 indicates unlock status.
1548
Ben Dooks9db829f2008-07-03 11:24:29 +01001549 mtdset= [ARM]
1550 ARM/S3C2412 JIVE boot control
1551
1552 See arch/arm/mach-s3c2412/mach-jive.c
1553
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001555 [HW] Make the MicroTouch USB driver use raw coordinates
1556 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001558 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001559 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001560 that could hold holes aka. UC entries.
1561
1562 mtrr_gran_size=nn[KMG] [X86]
1563 Used for mtrr cleanup. It is granularity of mtrr block.
1564 Default is 1.
1565 Large value could prevent small alignment from
1566 using up MTRRs.
1567
1568 mtrr_spare_reg_nr=n [X86]
1569 Format: <integer>
1570 Range: 0,7 : spare reg number
1571 Default : 1
1572 Used for mtrr cleanup. It is spare mtrr entries number.
1573 Set to 2 or more if your graphical card needs more.
1574
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1576
1577 NCR_D700= [HW,SCSI]
1578 See header of drivers/scsi/NCR_D700.c.
1579
1580 ncr5380= [HW,SCSI]
1581
1582 ncr53c400= [HW,SCSI]
1583
1584 ncr53c400a= [HW,SCSI]
1585
1586 ncr53c406a= [HW,SCSI]
1587
1588 ncr53c8xx= [HW,SCSI]
1589
1590 netdev= [NET] Network devices parameters
1591 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1592 Note that mem_start is often overloaded to mean
1593 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001594 This usage is only documented in each driver source
1595 file if at all.
1596
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001597 nf_conntrack.acct=
1598 [NETFILTER] Enable connection tracking flow accounting
1599 0 to disable accounting
1600 1 to enable accounting
1601 Default value depends on CONFIG_NF_CT_ACCT that is
1602 going to be removed in 2.6.29.
1603
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001605 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606
1607 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001608 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
Trond Myklebusta72b4422006-01-03 09:55:41 +01001610 nfs.callback_tcpport=
1611 [NFS] set the TCP port on which the NFSv4 callback
1612 channel should listen.
1613
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001614 nfs.cache_getent=
1615 [NFS] sets the pathname to the program which is used
1616 to update the NFS client cache entries.
1617
1618 nfs.cache_getent_timeout=
1619 [NFS] sets the timeout after which an attempt to
1620 update a cache entry is deemed to have failed.
1621
Trond Myklebust58df0952006-01-03 09:55:57 +01001622 nfs.idmap_cache_timeout=
1623 [NFS] set the maximum lifetime for idmapper cache
1624 entries.
1625
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001626 nfs.enable_ino64=
1627 [NFS] enable 64-bit inode numbers.
1628 If zero, the NFS client will fake up a 32-bit inode
1629 number for the readdir() and stat() syscalls instead
1630 of returning the full 64-bit number.
1631 The default is to return 64-bit inode numbers.
1632
Paul Mundt1e1030d2009-09-01 17:38:32 +09001633 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001634 when a NMI is triggered.
1635 Format: [state][,regs][,debounce][,die]
1636
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301637 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001638 Format: [panic,][num]
1639 Valid num: 0,1,2
1640 0 - turn nmi_watchdog off
1641 1 - use the IO-APIC timer for the NMI watchdog
1642 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001643 a performance counter. Note: This will use one
1644 performance counter and the local APIC's performance
1645 vector.
1646 When panic is specified, panic when an NMI watchdog
1647 timeout occurs.
1648 This is useful when you use a panic=... timeout and
1649 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001650 Instead of 1 and 2 it is possible to use the following
1651 symbolic names: lapic and ioapic
1652 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653
Anton Vorontsovbff38772009-07-08 11:10:56 -07001654 netpoll.carrier_timeout=
1655 [NET] Specifies amount of time (in seconds) that
1656 netpoll should wait for a carrier. By default netpoll
1657 waits 4 seconds.
1658
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001659 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 emulation library even if a 387 maths coprocessor
1661 is present.
1662
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001663 no_console_suspend
1664 [HW] Never suspend the console
1665 Disable suspending of consoles during suspend and
1666 hibernate operations. Once disabled, debugging
1667 messages can reach various consoles while the rest
1668 of the system is being put to sleep (ie, while
1669 debugging driver suspend/resume hooks). This may
1670 not work reliably with all consoles, but is known
1671 to work with serial and VGA consoles.
1672
Christoph Lameterc1aee212007-05-31 00:40:47 -07001673 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1674 caches in the slab allocator. Saves per-node memory,
1675 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001676
Randy Dunlapa9913042005-10-23 12:57:11 -07001677 noalign [KNL,ARM]
1678
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 noapic [SMP,APIC] Tells the kernel to not make use of any
1680 IOAPICs that may be present in the system.
1681
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 nobats [PPC] Do not use BATs for mapping kernel lowmem
1683 on "Classic" PPC cores.
1684
1685 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001686
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001687 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1688
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001689 nodelayacct [KNL] Disable per-task delay accounting
1690
Linus Torvalds1da177e2005-04-16 15:20:36 -07001691 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1692
Paul Mundt6902aa82008-09-21 17:14:42 +09001693 nodsp [SH] Disable hardware DSP at boot time.
1694
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301695 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001696
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 noexec [IA-64]
1698
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301699 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001700 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001702 noexec=off: disable non-executable mappings
1703
1704 noexec32 [X86-64]
1705 This affects only 32-bit executables.
1706 noexec32=on: enable non-executable mappings (default)
1707 read doesn't imply executable mappings
1708 noexec32=off: disable non-executable mappings
1709 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710
Paul Mundt6902aa82008-09-21 17:14:42 +09001711 nofpu [SH] Disable hardware FPU at boot time.
1712
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001713 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001714 register save and restore. The kernel will only save
1715 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716
Suresh Siddha0c752a92009-05-22 12:17:45 -07001717 noxsave [BUGS=X86] Disables x86 extended register state save
1718 and restore using xsave. The kernel will fallback to
1719 enabling legacy floating-point and sse state.
1720
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001721 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1722 wfi(ARM) instruction doesn't work correctly and not to
1723 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001724
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001725 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 instruction doesn't work correctly and not to
1727 use it.
1728
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001729 no_file_caps Tells the kernel not to honor file capabilities. The
1730 only way then for a file to be executed with privilege
1731 is to be setuid root or executed by root.
1732
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 nohalt [IA-64] Tells the kernel not to use the power saving
1734 function PAL_HALT_LIGHT when idle. This increases
1735 power-consumption. On the positive side, it reduces
1736 interrupt wake-up latency, which may improve performance
1737 in certain environments such as networked servers or
1738 real-time systems.
1739
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001740 nohz= [KNL] Boottime enable/disable dynamic ticks
1741 Valid arguments: on, off
1742 Default: on
1743
Paul Mundteeee7852009-04-02 12:31:16 +09001744 noiotrap [SH] Disables trapped I/O port accesses.
1745
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001746 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 disable unhandled interrupt sources.
1748
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301749 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001750 broken timer IRQ sources.
1751
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752 noisapnp [ISAPNP] Disables ISA PnP code.
1753
1754 noinitrd [RAM] Tells the kernel not to load any configured
1755 initial RAM disk.
1756
Weidong Han03ea8152009-04-17 16:42:15 +08001757 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1758 remapping.
1759
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 nointroute [IA-64]
1761
Tony Luck0aa366f2007-07-20 11:22:30 -07001762 nojitter [IA64] Disables jitter checking for ITC timers.
1763
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001766 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 noltlbs [PPC] Do not use large page/tlb entries for kernel
1769 lowmem mapping on PPC40x.
1770
Horms312f1f02006-02-22 09:57:55 +09001771 nomca [IA-64] Disable machine check abort handling
1772
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001773 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001774
Andres Salomon83d73842007-10-12 23:04:06 +02001775 nomfgpt [X86-32] Disable Multi-Function General Purpose
1776 Timer usage (for AMD Geode machines).
1777
Jiri Kosina016ddd92010-01-18 17:05:40 +01001778 nopat [X86] Disable PAT (page attribute table extension of
1779 pagetables) support.
1780
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001781 norandmaps Don't use address space randomization. Equivalent to
1782 echo 0 > /proc/sys/kernel/randomize_va_space
1783
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001784 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001785
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001786 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001787 with UP alternatives
1788
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 noresidual [PPC] Don't use residual data on PReP machines.
1790
Randy Dunlapa9913042005-10-23 12:57:11 -07001791 noresume [SWSUSP] Disables resume and restores original swap
1792 space.
1793
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 no-scroll [VGA] Disables scrollback.
1795 This is required for the Braillex ib80-piezo Braille
1796 reader made by F.H. Papenmeier (Germany).
1797
1798 nosbagart [IA-64]
1799
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001800 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001801
Len Brown61ec7562007-08-16 03:34:22 -04001802 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1803 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804
Dave Jones97842212007-07-15 23:41:05 -07001805 nosoftlockup [KNL] Disable the soft-lockup detector.
1806
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001807 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001808 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001809
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 nosync [HW,M68K] Disables sync negotiation for all devices.
1811
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001812 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
1814 nousb [USB] Disable the USB subsystem
1815
1816 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001817
Weidong Han2b2fd872009-04-17 16:42:12 +08001818 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1819
Fenghua Yua6c75b862008-03-14 13:57:08 -07001820 nptcg= [IA64] Override max number of concurrent global TLB
1821 purges which is reported from either PAL_VM_SUMMARY or
1822 SAL PALO.
1823
Yinghai Lu2b633e32010-02-10 01:20:37 -08001824 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1825 could support. nr_cpus=n : n >= 1 limits the kernel to
1826 supporting 'n' processors. Later in runtime you can not
1827 use hotplug cpu feature to put more cpu back to online.
1828 just like you compile the kernel NR_CPUS=n
1829
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001830 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1831
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001832 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1833 one of ['zone', 'node', 'default'] can be specified
1834 This can be set from sysctl after boot.
1835 See Documentation/sysctl/vm.txt for details.
1836
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001837 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1838 See Documentation/debugging-via-ohci1394.txt for more
1839 info.
1840
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001841 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1842 Rather than timing out after 20 ms if an EC
1843 command is not properly ACKed, override the length
1844 of the timeout. We have interrupts disabled while
1845 waiting for the ACK, so if this is set too high
1846 interrupts *may* be lost!
1847
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001848 omap_mux= [OMAP] Override bootloader pin multiplexing.
1849 Format: <mux_mode0.mode_name=value>...
1850 For example, to override I2C bus2:
1851 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1852
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 opl3= [HW,OSS]
1854 Format: <io>
1855
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 oprofile.timer= [HW]
1857 Use timer interrupt instead of performance counters
1858
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001859 oprofile.cpu_type= Force an oprofile cpu type
1860 This might be useful if you have an older oprofile
1861 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001862 Format: { arch_perfmon }
1863 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001864 perfmon on Intel CPUs instead of the
1865 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001866
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 osst= [HW,SCSI] SCSI Tape Driver
1868 Format: <buffer_size>,<write_threshold>
1869 See also Documentation/scsi/st.txt.
1870
1871 panic= [KNL] Kernel behaviour on panic
1872 Format: <timeout>
1873
1874 parkbd.port= [HW] Parallel port number the keyboard adapter is
1875 connected to, default is 0.
1876 Format: <parport#>
1877 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1878 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001879 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880
Randy Dunlapa9913042005-10-23 12:57:11 -07001881 parport= [HW,PPT] Specify parallel ports. 0 disables.
1882 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1883 Use 'auto' to force the driver to use any
1884 IRQ/DMA settings detected (the default is to
1885 ignore detected IRQ/DMA settings because of
1886 possible conflicts). You can specify the base
1887 address, IRQ, and DMA settings; IRQ and DMA
1888 should be numbers, or 'auto' (for using detected
1889 settings on that particular port), or 'nofifo'
1890 (to avoid using a FIFO even if it is detected).
1891 Parallel ports are assigned in the order they
1892 are specified on the command line, starting
1893 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894
Randy Dunlapa9913042005-10-23 12:57:11 -07001895 parport_init_mode= [HW,PPT]
1896 Configure VIA parallel port to operate in
1897 a specific mode. This is necessary on Pegasos
1898 computer where firmware has no options for setting
1899 up parallel port mode and sets it to spp.
1900 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 Format: [spp|ps2|epp|ecp|ecpepp]
1902
Randy Dunlapa9913042005-10-23 12:57:11 -07001903 pas2= [HW,OSS] Format:
1904 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1905
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 pas16= [HW,SCSI]
1907 See header of drivers/scsi/pas16.c.
1908
Andrew Mortondd287792006-03-23 03:00:57 -08001909 pause_on_oops=
1910 Halt all CPUs after the first oops has been printed for
1911 the specified number of seconds. This is to be used if
1912 your oopses keep scrolling off the screen.
1913
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 pcbit= [HW,ISDN]
1915
1916 pcd. [PARIDE]
1917 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001918 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919
Randy Dunlapa9913042005-10-23 12:57:11 -07001920 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001921 earlydump [X86] dump PCI config space before the kernel
1922 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001923 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001924 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001925 the hardware directly. Use this if your machine
1926 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001927 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001928 hardware access methods are allowed. Use this
1929 if you experience crashes upon bootup and you
1930 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001931 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001932 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001933 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001934 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001935 noaer [PCIE] If the PCIEAER kernel config parameter is
1936 enabled, this kernel boot option can be used to
1937 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001938 nodomains [PCI] Disable support for multiple PCI
1939 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301940 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001941 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001942 check_enable_amd_mmconf [X86] check for and enable
1943 properly configured MMIO access to PCI
1944 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001945 nomsi [MSI] If the PCI_MSI kernel config parameter is
1946 enabled, this kernel boot option can be used to
1947 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001948 noioapicquirk [APIC] Disable all boot interrupt quirks.
1949 Safety option to keep boot IRQs enabled. This
1950 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001951 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1952 primary IO-APIC for bridges that cannot disable
1953 boot IRQs. This fixes a source of spurious IRQs
1954 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001955 noioapicreroute [APIC] Disable workaround that uses the
1956 boot IRQ equivalent of an IRQ that connects to
1957 a chipset where boot IRQs cannot be disabled.
1958 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001959 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001960 routing table. These calls are known to be buggy
1961 on several machines and they hang the machine
1962 when used, but on other computers it's the only
1963 way to get the interrupt routing table. Try
1964 this option if the kernel is unable to allocate
1965 IRQs or discover secondary PCI buses on your
1966 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001967 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001968 Use with caution as certain devices share
1969 address decoders between ROMs and other
1970 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001971 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001972 expansion ROMs that do not already have
1973 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001974 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001975 assigned automatically to PCI devices. You can
1976 make the kernel exclude IRQs of your ISA cards
1977 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001978 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001979 of the PIRQ table (normally generated
1980 by the BIOS) if it is outside the
1981 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001982 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001983 useful if the kernel is unable to find your
1984 secondary buses and you want to tell it
1985 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001986 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001987 numbers ourselves, overriding
1988 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001989 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001990 in the BIOS $PIR table. This is needed on
1991 some systems with broken BIOSes, notably
1992 some HP Pavilion N5400 and Omnibook XE3
1993 notebooks. This will have no effect if ACPI
1994 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001995 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001996 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001997 use_crs [X86] Use PCI host bridge window information
1998 from ACPI. On BIOSes from 2008 or later, this
1999 is enabled by default. If you need to use this,
2000 please report a bug.
2001 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2002 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002003 routeirq Do IRQ routing for all PCI devices.
2004 This is normally done in pci_enable_device(),
2005 so this option is a temporary workaround
2006 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002007 skip_isa_align [X86] do not align io start addr, so can
2008 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002009 firmware [ARM] Do not re-enumerate the bus but instead
2010 just use the configuration from the
2011 bootloader. This is currently used on
2012 IXP2000 systems where the bus has to be
2013 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002014 noearly [X86] Don't do any early type 1 scanning.
2015 This might help on some broken boards which
2016 machine check when some devices' config space
2017 is read. But various workarounds are disabled
2018 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002019 bfsort Sort PCI devices into breadth-first order.
2020 This sorting is done to get a device
2021 order compatible with older (<= 2.4) kernels.
2022 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002023 cbiosize=nn[KMG] The fixed amount of bus space which is
2024 reserved for the CardBus bridge's IO window.
2025 The default value is 256 bytes.
2026 cbmemsize=nn[KMG] The fixed amount of bus space which is
2027 reserved for the CardBus bridge's memory
2028 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002029 resource_alignment=
2030 Format:
2031 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2032 Specifies alignment and device to reassign
2033 aligned memory resources.
2034 If <order of align> is not specified,
2035 PAGE_SIZE is used as alignment.
2036 PCI-PCI bridge can be specified, if resource
2037 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002038 ecrc= Enable/disable PCIe ECRC (transaction layer
2039 end-to-end CRC checking).
2040 bios: Use BIOS/firmware settings. This is the
2041 the default.
2042 off: Turn ECRC off
2043 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002044
Chuck Ebberte5665a42008-09-24 20:40:34 -04002045 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2046 Management.
2047 off Disable ASPM.
2048 force Enable ASPM even on devices that claim not to support it.
2049 WARNING: Forcing ASPM on may cause system lockups.
2050
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002051 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockib27759f2010-06-18 17:04:22 +02002052 Format: {auto|force}[,nomsi]
2053 auto Use native PCIe PME signaling if the BIOS allows the
2054 kernel to control PCIe config registers of root ports.
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002055 force Use native PCIe PME signaling even if the BIOS refuses
2056 to allow the kernel to control the relevant PCIe config
2057 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002058 nomsi Do not use MSI for native PCIe PME signaling (this makes
2059 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002060
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 pcmv= [HW,PCMCIA] BadgePAD 4
2062
2063 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002064 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065
2066 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2067 boot time.
2068 Format: { 0 | 1 }
2069 See arch/parisc/kernel/pdc_chassis.c
2070
Tejun Heof58dc012009-08-14 15:00:50 +09002071 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002072 Currently supported values are "embed" and "page".
2073 Archs may support subset or none of the selections.
2074 See comments in mm/percpu.c for details on each
2075 allocator. This parameter is primarily for debugging
2076 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002077
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002079 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
2081 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002082 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
2084 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002085 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002086
2087 plip= [PPT,NET] Parallel port network link
2088 Format: { parport<nr> | timid | 0 }
2089 See also Documentation/parport.txt.
2090
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002091 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2092 Override pmtimer IOPort with a hex value.
2093 e.g. pmtmr=0x508
2094
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002095 pnp.debug [PNP]
2096 Enable PNP debug messages. This depends on the
2097 CONFIG_PNP_DEBUG_MESSAGES option.
2098
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 pnpacpi= [ACPI]
2100 { off }
2101
2102 pnpbios= [ISAPNP]
2103 { on | off | curr | res | no-curr | no-res }
2104
2105 pnp_reserve_irq=
2106 [ISAPNP] Exclude IRQs for the autoconfiguration
2107
2108 pnp_reserve_dma=
2109 [ISAPNP] Exclude DMAs for the autoconfiguration
2110
2111 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002112 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
2114 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002115 [ISAPNP] Exclude memory regions for the
2116 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 Ranges are in pairs (memory base and size).
2118
Randy Dunlap4af94f32009-04-17 18:30:28 -07002119 ports= [IP_VS_FTP] IPVS ftp helper module
2120 Default is 21.
2121 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2122 may be specified.
2123 Format: <port>,<port>....
2124
Ingo Molnar45807a12007-07-15 23:40:10 -07002125 print-fatal-signals=
2126 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002127
2128 If enabled, warn about various signal handling
2129 related application anomalies: too many signals,
2130 too many POSIX.1 timers, fatal signals causing a
2131 coredump - etc.
2132
2133 If you hit the warning due to signal overflow,
2134 you might want to try "ulimit -i unlimited".
2135
Ingo Molnar45807a12007-07-15 23:40:10 -07002136 default: off.
2137
Randy Dunlape84845c2007-07-15 23:40:25 -07002138 printk.time= Show timing data prefixed to each printk message line
2139 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2140
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002141 processor.max_cstate= [HW,ACPI]
2142 Limit processor to maximum C-state
2143 max_cstate=9 overrides any DMI blacklist limit.
2144
2145 processor.nocst [HW,ACPI]
2146 Ignore the _CST method to determine C-states,
2147 instead using the legacy FADT method
2148
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002150 Format: [schedule,]<number>
2151 Param: "schedule" - profile schedule points.
2152 Param: <number> - step/bucket size as a power of 2 for
2153 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002154 Param: "sleep" - profile D-state sleeping (millisecs).
2155 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002156 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2159 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002160 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161
Randy Dunlapa9913042005-10-23 12:57:11 -07002162 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2163 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2165 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002166 psmouse.resetafter= [HW,MOUSE]
2167 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 (0 = never).
2169 psmouse.resolution=
2170 [HW,MOUSE] Set desired mouse resolution, in dpi.
2171 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002172 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173 0 = disabled, 1 = enabled (default).
2174
2175 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002176 Format:
2177 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178
2179 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002180 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181
Kay Sieversdc8c8582007-08-15 12:25:38 +02002182 pty.legacy_count=
2183 [KNL] Number of legacy pty's. Overwrites compiled-in
2184 default number.
2185
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002186 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002187
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 r128= [HW,DRM]
2189
2190 raid= [HW,RAID]
2191 See Documentation/md.txt.
2192
Randy Dunlapa9913042005-10-23 12:57:11 -07002193 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002194 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002195
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002197 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002199 rcupdate.blimit= [KNL,BOOT]
2200 Set maximum number of finished RCU callbacks to process
2201 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002202
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002203 rcupdate.qhimark= [KNL,BOOT]
2204 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002205 RCU callbacks over which batch limiting is disabled.
2206
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002207 rcupdate.qlowmark= [KNL,BOOT]
2208 Set threshold of queued RCU callbacks below which
2209 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002210
Olof Johanssonffdfc402005-09-06 15:17:19 -07002211 rdinit= [KNL]
2212 Format: <full_path>
2213 Run specified binary instead of /init from the ramdisk,
2214 used for early userspace startup. See initrd.
2215
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002216 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002218 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219
Paul Jackson46b6d942008-07-04 10:00:09 -07002220 relax_domain_level=
2221 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002222 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002223
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2225
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002226 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002227 Format: nn[KMG]
2228 Reserves a hole at the top of the kernel virtual
2229 address space.
2230
Vivek Goyal7e962872006-09-27 01:50:44 -07002231 reset_devices [KNL] Force drivers to reset the underlying device
2232 during initialization.
2233
Randy Dunlapa9913042005-10-23 12:57:11 -07002234 resume= [SWSUSP]
2235 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002236
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002237 resume_offset= [SWSUSP]
2238 Specify the offset from the beginning of the partition
2239 given by "resume=" at which the swap header is located,
2240 in <PAGE_SIZE> units (needed only for swap files).
2241 See Documentation/power/swsusp-and-swap-files.txt
2242
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002243 retain_initrd [RAM] Keep initrd memory after extraction
2244
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 rhash_entries= [KNL,NET]
2246 Set number of hash buckets for route cache
2247
2248 riscom8= [HW,SERIAL]
2249 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2250
2251 ro [KNL] Mount root device read-only on boot
2252
2253 root= [KNL] Root filesystem
2254
2255 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2256 mount the root filesystem
2257
2258 rootflags= [KNL] Set root filesystem mount option string
2259
2260 rootfstype= [KNL] Set root filesystem type
2261
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002262 rootwait [KNL] Wait (indefinitely) for root device to show up.
2263 Useful for devices that are detected asynchronously
2264 (e.g. USB and MMC devices).
2265
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 rw [KNL] Mount root device read-write on boot
2267
2268 S [KNL] Run init in single mode
2269
2270 sa1100ir [NET]
2271 See drivers/net/irda/sa1100_ir.c.
2272
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002274
Mike Travisf6630112009-11-17 18:22:15 -06002275 sched_debug [KNL] Enables verbose scheduler debug messages.
2276
Linus Torvalds1da177e2005-04-16 15:20:36 -07002277 scsi_debug_*= [SCSI]
2278 See drivers/scsi/scsi_debug.c.
2279
2280 scsi_default_dev_flags=
2281 [SCSI] SCSI default device flags
2282 Format: <integer>
2283
2284 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2285 Format: <vendor>:<model>:<flags>
2286 (flags are integer value)
2287
Randy Dunlap6af66322007-11-14 16:52:25 -08002288 scsi_logging_level= [SCSI] a bit mask of logging levels
2289 See drivers/scsi/scsi_logging.h for bits. Also
2290 settable via sysctl at dev.scsi.logging_level
2291 (/proc/sys/dev/scsi/logging_level).
2292 There is also a nice 'scsi_logging_level' script in the
2293 S390-tools package, available for download at
2294 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002296 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2297 discovered. async scans them in kernel threads,
2298 allowing boot to proceed. none ignores them, expecting
2299 user space to do the scan.
2300
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002301 security= [SECURITY] Choose a security module to enable at boot.
2302 If this boot parameter is not specified, only the first
2303 security module asking for security registration will be
2304 loaded. An invalid security module name will be treated
2305 as if no module has been chosen.
2306
2307 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 Format: { "0" | "1" }
2309 See security/selinux/Kconfig help text.
2310 0 -- disable.
2311 1 -- enable.
2312 Default value is set via kernel config option.
2313 If enabled at boot time, /selinux/disable can be used
2314 later to disable prior to initial policy load.
2315
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002316 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002317
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 shapers= [NET]
2319 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002320
Yinghai Lub05f78f2008-08-22 01:32:50 -07002321 show_msr= [x86] show boot-time MSR settings
2322 Format: { <integer> }
2323 Show boot-time (BIOS-initialized) MSR settings.
2324 The parameter means the number of CPUs to show,
2325 for example 1 means boot CPU only.
2326
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 sim710= [SCSI,HW]
2328 See header of drivers/scsi/sim710.c.
2329
2330 simeth= [IA-64]
2331 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002332
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 slram= [HW,MTD]
2334
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002335 slub_debug[=options[,slabs]] [MM, SLUB]
2336 Enabling slub_debug allows one to determine the
2337 culprit if slab objects become corrupted. Enabling
2338 slub_debug can create guard zones around objects and
2339 may poison objects when not in use. Also tracks the
2340 last alloc / free. For more information see
2341 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002342
2343 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002344 Determines the maximum allowed order for slabs.
2345 A high setting may cause OOMs due to memory
2346 fragmentation. For more information see
2347 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002348
2349 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002350 The minimum number of objects per slab. SLUB will
2351 increase the slab order up to slub_max_order to
2352 generate a sufficiently large slab able to contain
2353 the number of objects indicated. The higher the number
2354 of objects the smaller the overhead of tracking slabs
2355 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002356 For more information see Documentation/vm/slub.txt.
2357
2358 slub_min_order= [MM, SLUB]
2359 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002360 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002361 For more information see Documentation/vm/slub.txt.
2362
2363 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002364 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002365 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002366 allocs to different slabs. Debug options disable
2367 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002368 For more information see Documentation/vm/slub.txt.
2369
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 smart2= [HW]
2371 Format: <io1>[,<io2>[,...,<io8>]]
2372
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002373 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002374 attempt to substitute SMP alternatives once at boot.
2375
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002376 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2377 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2378 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2379 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2380 smsc-ircc2.ircc_irq= [HW] IRQ line
2381 smsc-ircc2.ircc_dma= [HW] DMA channel
2382 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2383 0: Toshiba Satellite 1800 (GP data pin select)
2384 1: Fast pin select (default)
2385 2: ATC IRMode
2386
Linus Torvalds1da177e2005-04-16 15:20:36 -07002387 snd-ad1816a= [HW,ALSA]
2388
2389 snd-ad1848= [HW,ALSA]
2390
2391 snd-ali5451= [HW,ALSA]
2392
2393 snd-als100= [HW,ALSA]
2394
2395 snd-als4000= [HW,ALSA]
2396
2397 snd-azt2320= [HW,ALSA]
2398
2399 snd-cmi8330= [HW,ALSA]
2400
2401 snd-cmipci= [HW,ALSA]
2402
2403 snd-cs4231= [HW,ALSA]
2404
2405 snd-cs4232= [HW,ALSA]
2406
2407 snd-cs4236= [HW,ALSA]
2408
2409 snd-cs4281= [HW,ALSA]
2410
2411 snd-cs46xx= [HW,ALSA]
2412
2413 snd-dt019x= [HW,ALSA]
2414
2415 snd-dummy= [HW,ALSA]
2416
2417 snd-emu10k1= [HW,ALSA]
2418
2419 snd-ens1370= [HW,ALSA]
2420
2421 snd-ens1371= [HW,ALSA]
2422
2423 snd-es968= [HW,ALSA]
2424
2425 snd-es1688= [HW,ALSA]
2426
2427 snd-es18xx= [HW,ALSA]
2428
2429 snd-es1938= [HW,ALSA]
2430
2431 snd-es1968= [HW,ALSA]
2432
2433 snd-fm801= [HW,ALSA]
2434
2435 snd-gusclassic= [HW,ALSA]
2436
2437 snd-gusextreme= [HW,ALSA]
2438
2439 snd-gusmax= [HW,ALSA]
2440
2441 snd-hdsp= [HW,ALSA]
2442
2443 snd-ice1712= [HW,ALSA]
2444
2445 snd-intel8x0= [HW,ALSA]
2446
2447 snd-interwave= [HW,ALSA]
2448
2449 snd-interwave-stb=
2450 [HW,ALSA]
2451
2452 snd-korg1212= [HW,ALSA]
2453
2454 snd-maestro3= [HW,ALSA]
2455
2456 snd-mpu401= [HW,ALSA]
2457
2458 snd-mtpav= [HW,ALSA]
2459
2460 snd-nm256= [HW,ALSA]
2461
2462 snd-opl3sa2= [HW,ALSA]
2463
2464 snd-opti92x-ad1848=
2465 [HW,ALSA]
2466
2467 snd-opti92x-cs4231=
2468 [HW,ALSA]
2469
2470 snd-opti93x= [HW,ALSA]
2471
2472 snd-pmac= [HW,ALSA]
2473
2474 snd-rme32= [HW,ALSA]
2475
2476 snd-rme96= [HW,ALSA]
2477
2478 snd-rme9652= [HW,ALSA]
2479
2480 snd-sb8= [HW,ALSA]
2481
2482 snd-sb16= [HW,ALSA]
2483
2484 snd-sbawe= [HW,ALSA]
2485
2486 snd-serial= [HW,ALSA]
2487
2488 snd-sgalaxy= [HW,ALSA]
2489
2490 snd-sonicvibes= [HW,ALSA]
2491
2492 snd-sun-amd7930=
2493 [HW,ALSA]
2494
2495 snd-sun-cs4231= [HW,ALSA]
2496
2497 snd-trident= [HW,ALSA]
2498
2499 snd-usb-audio= [HW,ALSA,USB]
2500
2501 snd-via82xx= [HW,ALSA]
2502
2503 snd-virmidi= [HW,ALSA]
2504
2505 snd-wavefront= [HW,ALSA]
2506
2507 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002508
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002509 softlockup_panic=
2510 [KNL] Should the soft-lockup detector generate panics.
2511
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2513 See Documentation/sonypi.txt
2514
2515 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002516 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002517
2518 spia_io_base= [HW,MTD]
2519 spia_fio_base=
2520 spia_pedr=
2521 spia_peddr=
2522
2523 sscape= [HW,OSS]
2524 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002525
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2527 See Documentation/scsi/st.txt.
2528
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002529 stacktrace [FTRACE]
2530 Enabled the stack tracer on boot up.
2531
Linus Torvalds1da177e2005-04-16 15:20:36 -07002532 sti= [PARISC,HW]
2533 Format: <num>
2534 Set the STI (builtin display/keyboard on the HP-PARISC
2535 machines) console (graphic card) which should be used
2536 as the initial boot-console.
2537 See also comment in drivers/video/console/sticore.c.
2538
2539 sti_font= [HW]
2540 See comment in drivers/video/console/sticore.c.
2541
2542 stifb= [HW]
2543 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2544
Trond Myklebustcbf11072009-08-09 15:06:19 -04002545 sunrpc.min_resvport=
2546 sunrpc.max_resvport=
2547 [NFS,SUNRPC]
2548 SunRPC servers often require that client requests
2549 originate from a privileged port (i.e. a port in the
2550 range 0 < portnr < 1024).
2551 An administrator who wishes to reserve some of these
2552 ports for other uses may adjust the range that the
2553 kernel's sunrpc client considers to be privileged
2554 using these two parameters to set the minimum and
2555 maximum port values.
2556
Greg Banks42a7fc42007-03-06 01:42:23 -08002557 sunrpc.pool_mode=
2558 [NFS]
2559 Control how the NFS server code allocates CPUs to
2560 service thread pools. Depending on how many NICs
2561 you have and where their interrupts are bound, this
2562 option will affect which CPUs will do NFS serving.
2563 Note: this parameter cannot be changed while the
2564 NFS server is running.
2565
2566 auto the server chooses an appropriate mode
2567 automatically using heuristics
2568 global a single global pool contains all CPUs
2569 percpu one pool for each CPU
2570 pernode one pool for each NUMA node (equivalent
2571 to global on non-NUMA machines)
2572
Trond Myklebustcbf11072009-08-09 15:06:19 -04002573 sunrpc.tcp_slot_table_entries=
2574 sunrpc.udp_slot_table_entries=
2575 [NFS,SUNRPC]
2576 Sets the upper limit on the number of simultaneous
2577 RPC calls that can be sent from the client to a
2578 server. Increasing these values may allow you to
2579 improve throughput, but will also increase the
2580 amount of memory reserved for use by the client.
2581
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002583
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584 switches= [HW,M68k]
2585
2586 sym53c416= [HW,SCSI]
2587 See header of drivers/scsi/sym53c416.c.
2588
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002589 sysrq_always_enabled
2590 [KNL]
2591 Ignore sysrq setting - this boot parameter will
2592 neutralize any effect of /proc/sys/kernel/sysrq.
2593 Useful for debugging.
2594
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595 t128= [HW,SCSI]
2596 See header of drivers/scsi/t128.c.
2597
2598 tdfx= [HW,DRM]
2599
David Brownell77437fd2008-07-23 21:28:33 -07002600 test_suspend= [SUSPEND]
2601 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2602 standby suspend) as the system sleep state to briefly
2603 enter during system startup. The system is woken from
2604 this state using a wakeup-capable RTC alarm.
2605
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606 thash_entries= [KNL,NET]
2607 Set number of hash buckets for TCP connection
2608
Len Brownf8707ec2007-08-12 00:12:54 -04002609 thermal.act= [HW,ACPI]
2610 -1: disable all active trip points in all thermal zones
2611 <degrees C>: override all lowest active trip points
2612
Len Brownc52a7412007-08-14 15:49:32 -04002613 thermal.crt= [HW,ACPI]
2614 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002615 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002616
Len Brownf5487142007-08-12 00:12:44 -04002617 thermal.nocrt= [HW,ACPI]
2618 Set to disable actions on ACPI thermal zone
2619 critical and hot trip points.
2620
Len Brown72b33ef2007-08-12 00:12:17 -04002621 thermal.off= [HW,ACPI]
2622 1: disable ACPI thermal control
2623
Len Browna70cdc52007-08-12 00:12:35 -04002624 thermal.psv= [HW,ACPI]
2625 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002626 <degrees C>: override all passive trip points to this
2627 value
Len Browna70cdc52007-08-12 00:12:35 -04002628
Len Brown730ff342007-08-12 00:12:26 -04002629 thermal.tzp= [HW,ACPI]
2630 Specify global default ACPI thermal zone polling rate
2631 <deci-seconds>: poll all this frequency
2632 0: no polling (default)
2633
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634 tmscsim= [HW,SCSI]
2635 See comment before function dc390_setup() in
2636 drivers/scsi/tmscsim.c.
2637
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002638 topology= [S390]
2639 Format: {off | on}
2640 Specify if the kernel should make use of the cpu
2641 topology informations if the hardware supports these.
2642 The scheduler will make use of these informations and
2643 e.g. base its process migration decisions on it.
2644 Default is off.
2645
Linus Torvalds1da177e2005-04-16 15:20:36 -07002646 tp720= [HW,PS2]
2647
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002648 tpm_suspend_pcr=[HW,TPM]
2649 Format: integer pcr id
2650 Specify that at suspend time, the tpm driver
2651 should extend the specified pcr with zeros,
2652 as a workaround for some chips which fail to
2653 flush the last written pcr on TPM_SaveState.
2654 This will guarantee that all the other pcrs
2655 are saved.
2656
Li Zefan9d612be2009-06-24 17:33:15 +08002657 trace_buf_size=nn[KMG]
2658 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002659
Li Zefan020e5f82009-07-01 10:47:05 +08002660 trace_event=[event-list]
2661 [FTRACE] Set and start specified trace events in order
2662 to facilitate early boot debugging.
2663 See also Documentation/trace/events.txt
2664
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002666 Format:
2667 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2668
Alok Kataria395628e2008-10-24 17:22:01 -07002669 tsc= Disable clocksource-must-verify flag for TSC.
2670 Format: <string>
2671 [x86] reliable: mark tsc clocksource as reliable, this
2672 disables clocksource verification at runtime.
2673 Used to enable high-resolution timer mode on older
2674 hardware, and in virtualized environment.
2675
Randy Dunlapa9913042005-10-23 12:57:11 -07002676 turbografx.map[2|3]= [HW,JOY]
2677 TurboGraFX parallel port interface
2678 Format:
2679 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680 See also Documentation/input/joystick-parport.txt
2681
2682 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2683 See header of drivers/scsi/u14-34f.c.
2684
2685 uart401= [HW,OSS]
2686 Format: <io>,<irq>
2687
2688 uart6850= [HW,OSS]
2689 Format: <io>,<irq>
2690
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002691 uhash_entries= [KNL,NET]
2692 Set number of hash buckets for UDP/UDP-Lite connections
2693
Alan Stern5f8364b2006-12-05 16:29:55 -05002694 uhci-hcd.ignore_oc=
2695 [USB] Ignore overcurrent events (default N).
2696 Some badly-designed motherboards generate lots of
2697 bogus events, for ports that aren't wired to
2698 anything. Set this parameter to avoid log spamming.
2699 Note that genuine overcurrent events won't be
2700 reported either.
2701
Simon Arlotte3a61b02008-07-19 23:32:54 +01002702 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302703 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002704 Set unknown_nmi_panic=1 early on boot.
2705
Alan Sternb5e795f2007-02-20 15:00:53 -05002706 usbcore.autosuspend=
2707 [USB] The autosuspend time delay (in seconds) used
2708 for newly-detected USB devices (default 2). This
2709 is the time required before an idle device will be
2710 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002711 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002712
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002713 usbcore.usbfs_snoop=
2714 [USB] Set to log all usbfs traffic (default 0 = off).
2715
2716 usbcore.blinkenlights=
2717 [USB] Set to cycle leds on hubs (default 0 = off).
2718
2719 usbcore.old_scheme_first=
2720 [USB] Start with the old device initialization
2721 scheme (default 0 = off).
2722
2723 usbcore.use_both_schemes=
2724 [USB] Try the other device initialization scheme
2725 if the first one fails (default 1 = enabled).
2726
2727 usbcore.initial_descriptor_timeout=
2728 [USB] Specifies timeout for the initial 64-byte
2729 USB_REQ_GET_DESCRIPTOR request in milliseconds
2730 (default 5000 = 5.0 seconds).
2731
Linus Torvalds1da177e2005-04-16 15:20:36 -07002732 usbhid.mousepoll=
2733 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002734
Alan Sternd4f373e2008-11-10 14:07:45 -05002735 usb-storage.delay_use=
2736 [UMS] The delay in seconds before a new device is
2737 scanned for Logical Units (default 5).
2738
2739 usb-storage.quirks=
2740 [UMS] A list of quirks entries to supplement or
2741 override the built-in unusual_devs list. List
2742 entries are separated by commas. Each entry has
2743 the form VID:PID:Flags where VID and PID are Vendor
2744 and Product ID values (4-digit hex numbers) and
2745 Flags is a set of characters, each corresponding
2746 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002747 a = SANE_SENSE (collect more than 18 bytes
2748 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002749 b = BAD_SENSE (don't collect more than 18
2750 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002751 c = FIX_CAPACITY (decrease the reported
2752 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002753 h = CAPACITY_HEURISTICS (decrease the
2754 reported device capacity by one
2755 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002756 i = IGNORE_DEVICE (don't bind to this
2757 device);
2758 l = NOT_LOCKABLE (don't try to lock and
2759 unlock ejectable media);
2760 m = MAX_SECTORS_64 (don't transfer more
2761 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002762 o = CAPACITY_OK (accept the capacity
2763 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002764 r = IGNORE_RESIDUE (the device reports
2765 bogus residue values);
2766 s = SINGLE_LUN (the device has only one
2767 Logical Unit);
2768 w = NO_WP_DETECT (don't test whether the
2769 medium is write-protected).
2770 Example: quirks=0419:aaf5:rl,0421:0433:rc
2771
Ian Campbell14315592010-02-17 10:38:10 +00002772 userpte=
2773 [X86] Flags controlling user PTE allocations.
2774
2775 nohigh = do not allocate PTE pages in
2776 HIGHMEM regardless of setting
2777 of CONFIG_HIGHPTE.
2778
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302779 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002780 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002781 vdso=1: enable VDSO (default)
2782 vdso=0: disable VDSO mapping
2783
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302784 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002785 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2786 vdso32=1: enable 32-bit VDSO (default)
2787 vdso32=0: disable 32-bit VDSO mapping
2788
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002789 vector= [IA-64,SMP]
2790 vector=percpu: enable percpu vector domain
2791
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792 video= [FB] Frame buffer configuration
2793 See Documentation/fb/modedb.txt.
2794
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002795 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002796 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002797 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002798 Use vga=ask for menu.
2799 This is actually a boot loader parameter; the value is
2800 passed to the kernel using a special protocol.
2801
Randy Dunlapa9913042005-10-23 12:57:11 -07002802 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803 size of <nn>. This can be used to increase the
2804 minimum size (128MB on x86). It can also be used to
2805 decrease the size and leave more room for directly
2806 mapped kernel RAM.
2807
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002808 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2809 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002810
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002811 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2812 Format: <command>
2813
2814 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2815 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002816
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002817 vt.cur_default= [VT] Default cursor shape.
2818 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2819 the parameters of the <Esc>[?A;B;Cc escape sequence;
2820 see VGA-softcursor.txt. Default: 2 = underline.
2821
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002822 vt.default_blu= [VT]
2823 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2824 Change the default blue palette of the console.
2825 This is a 16-member array composed of values
2826 ranging from 0-255.
2827
2828 vt.default_grn= [VT]
2829 Format: <green0>,<green1>,<green2>,...,<green15>
2830 Change the default green palette of the console.
2831 This is a 16-member array composed of values
2832 ranging from 0-255.
2833
2834 vt.default_red= [VT]
2835 Format: <red0>,<red1>,<red2>,...,<red15>
2836 Change the default red palette of the console.
2837 This is a 16-member array composed of values
2838 ranging from 0-255.
2839
2840 vt.default_utf8=
2841 [VT]
2842 Format=<0|1>
2843 Set system-wide default UTF-8 mode for all tty's.
2844 Default is 1, i.e. UTF-8 mode is enabled for all
2845 newly opened terminals.
2846
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002847 vt.global_cursor_default=
2848 [VT]
2849 Format=<-1|0|1>
2850 Set system-wide default for whether a cursor
2851 is shown on new VTs. Default is -1,
2852 i.e. cursors will be created by default unless
2853 overridden by individual drivers. 0 will hide
2854 cursors, 1 will display them.
2855
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856 waveartist= [HW,OSS]
2857 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002858
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859 wd33c93= [HW,SCSI]
2860 See header of drivers/scsi/wd33c93.c.
2861
2862 wd7000= [HW,SCSI]
2863 See header of drivers/scsi/wd7000.c.
2864
Randy Dunlap4724ba572010-05-03 11:42:52 -07002865 watchdog timers [HW,WDT] For information on watchdog timers,
2866 see Documentation/watchdog/watchdog-parameters.txt
2867 or other driver-specific files in the
2868 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002870 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2871 default x2apic cluster mode on platforms
2872 supporting x2apic.
2873
Jacob Panbb24c472009-09-02 07:37:17 -07002874 x86_mrst_timer= [X86-32,APBT]
2875 Choose timer option for x86 Moorestown MID platform.
2876 Two valid options are apbt timer only and lapic timer
2877 plus one apbt timer for broadcast timer.
2878 x86_mrst_timer=apbt_only | lapic_and_apbt
2879
Linus Torvalds1da177e2005-04-16 15:20:36 -07002880 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2881 xd_geo= See header of drivers/block/xd.c.
2882
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002883 xen_emul_unplug= [HW,X86,XEN]
2884 Unplug Xen emulated devices
2885 Format: [unplug0,][unplug1]
2886 ide-disks -- unplug primary master IDE devices
2887 aux-ide-disks -- unplug non-primary-master IDE devices
2888 nics -- unplug network devices
2889 all -- unplug all emulated devices (NICs and IDE disks)
2890 ignore -- continue loading the Xen platform PCI driver even
2891 if the version check failed
2892
Linus Torvalds1da177e2005-04-16 15:20:36 -07002893 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002894 Format:
2895 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002896
Randy Dunlapa9913042005-10-23 12:57:11 -07002897______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002898
2899TODO:
2900
2901 Add documentation for ALSA options.
2902 Add more DRM drivers.