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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.
Alan Cox9cfe2682011-01-25 14:18:38 +000046 DRM Direct Rendering Management support is enabled.
47 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
49 EFI EFI Partitioning (GPT) is enabled
50 EIDE EIDE/ATAPI support is enabled.
51 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070052 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050055 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070057 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080058 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 ISAPNP ISA PnP code is enabled.
60 ISDN Appropriate ISDN support is enabled.
61 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050062 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020063 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070064 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 LP Printer support is enabled.
66 LOOP Loopback device support is enabled.
67 M68k M68k architecture is enabled.
68 These options have more detailed description inside of
69 Documentation/m68k/kernel-options.txt.
70 MCA MCA bus support is enabled.
71 MDA MDA console support is enabled.
72 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070073 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070074 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 NET Appropriate network support is enabled.
76 NUMA NUMA support is enabled.
77 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.
Randy Dunlap163475f2010-08-14 12:36:14 -070092 A lot of drivers have their options described inside
93 the Documentation/scsi/ sub-directory.
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.
John Johansenc1c124e2010-07-29 14:48:09 -070096 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090098 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500103 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300104 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500106 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700114 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700117 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100119 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121In addition, the following text indicates that the option:
122
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
126
127Parameters denoted with BOOT are actually interpreted by the boot
128loader, and have no meaning to the kernel directly.
129Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500130need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Karsten Weiss55588702007-02-13 13:26:21 +0100132There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700133See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100134
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136a trailing = on the name of any parameter states that that parameter will
137be entered as an environment variable, whereas its absence indicates that
138it will appear as a kernel argument readable via /proc/cmdline by programs
139running once the system is up.
140
jens m. noedler9c4751f2006-09-29 02:00:27 -0700141The number of kernel parameters is not limited, but the length of the
142complete command line (parameters including spaces etc.) is limited to
143a fixed number of characters. This limit depends on the architecture
144and is between 256 and 4096 characters. It is defined in the file
145./include/asm/setup.h as COMMAND_LINE_SIZE.
146
Ahmed S. Darwish7a19a232011-02-20 20:08:35 -0800147Finally, the [KMG] suffix is commonly described after a number of kernel
148parameter values. These 'K', 'M', and 'G' letters represent the _binary_
149multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
150bytes respectively. Such letter suffixes can also be entirely omitted.
151
jens m. noedler9c4751f2006-09-29 02:00:27 -0700152
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530153 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800154 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500155 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 force -- enable ACPI if default was off
157 off -- disable ACPI if default was on
158 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700159 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800161 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800162 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163
Randy Dunlap53471122008-03-12 18:10:51 -0400164 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Len Browna1fdcc02007-03-11 03:26:14 -0400166 acpi_apic_instance= [ACPI, IOAPIC]
167 Format: <int>
168 2: use 2nd APIC table, if available
169 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400170 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400171
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200172 acpi_backlight= [HW,ACPI]
173 acpi_backlight=vendor
174 acpi_backlight=video
175 If set to vendor, prefer vendor specific driver
176 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
177 of the ACPI video.ko driver.
178
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700179 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
180 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700182 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
183 debug output. Bits in debug_layer correspond to a
184 _COMPONENT in an ACPI source file, e.g.,
185 #define _COMPONENT ACPI_PCI_COMPONENT
186 Bits in debug_level correspond to a level in
187 ACPI_DEBUG_PRINT statements, e.g.,
188 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600189 The debug_level mask defaults to "info". See
190 Documentation/acpi/debug.txt for more information about
191 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600193 Enable processor driver info messages:
194 acpi.debug_layer=0x20000000
195 Enable PCI/PCI interrupt routing info messages:
196 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700197 Enable AML "Debug" output, i.e., stores to the Debug
198 object while interpreting AML:
199 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700200 Enable all messages related to ACPI hardware:
201 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200202
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700203 Some values produce so much output that the system is
204 unusable. The "log_buf_len" parameter may be useful
205 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800206
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
209 default in APIC mode
210
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
213 default in PIC mode
214
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
217
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
219 use by PCI
220 Format: <irq>,<irq>...
221
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
226
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
231
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530232 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
236
Randy Dunlap4af94f32009-04-17 18:30:28 -0700237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
239
240 acpi_serialize [HW,ACPI] force serialization of AML methods
241
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
245
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Amerigo Wangc3b07952011-05-10 21:09:38 +0200248 old_ordering, nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700249 See Documentation/power/video.txt for information on
250 s3_bios and s3_mode.
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200259 nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700264
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
268
Luca Tettamanti7e905602009-03-30 00:01:27 +0200269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
284
Randy Dunlap4af94f32009-04-17 18:30:28 -0700285 add_efi_memmap [EFI; X86] Include EFI memory map in
286 kernel's map of available physical RAM.
287
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700288 agp= [AGP]
289 { off | try_unsupported }
290 off: disable AGP support
291 try_unsupported: try to drive unsupported chipsets
292 (may crash computer or cause data corruption)
293
Randy Dunlapbcfde332010-06-07 17:10:38 -0700294 ALSA [HW,ALSA]
295 See Documentation/sound/alsa/alsa-parameters.txt
296
Russell Kingd944d542010-02-20 16:13:29 +0000297 alignment= [KNL,ARM]
298 Allow the default userspace alignment fault handler
299 behaviour to be specified. Bit 0 enables warnings,
300 bit 1 enables fixups, and bit 2 sends a segfault.
301
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200302 align_va_addr= [X86-64]
303 Align virtual addresses by clearing slice [14:12] when
304 allocating a VMA at process creation time. This option
305 gives you up to 3% performance improvement on AMD F15h
306 machines (where it is enabled by default) for a
307 CPU-intensive style benchmark, and it can vary highly in
308 a microbenchmark depending on workload and compiler.
309
310 1: only for 32-bit processes
311 2: only for 64-bit processes
312 on: enable for both 32- and 64-bit processes
313 off: disable for both 32- and 64-bit processes
314
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200315 amd_iommu= [HW,X86-84]
316 Pass parameters to the AMD IOMMU driver in the system.
317 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900318 fullflush - enable flushing of IO/TLB entries when
319 they are unmapped. Otherwise they are
320 flushed before they will be reused, which
321 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200322 off - do not initialize any AMD IOMMU found in
323 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
327 Format: <a>,<b>
328 See also Documentation/kernel/input/joystick.txt
329
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
334
Randy Dunlapa9913042005-10-23 12:57:11 -0700335 apc= [HW,SPARC]
336 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 Format: noidle
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
341
Randy Dunlapca1eda22009-05-06 16:02:58 -0700342 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700343 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700347
Brian Haleyb0f83b22010-02-04 13:36:50 -0800348 autoconf= [IPV6]
349 See Documentation/networking/ipv6.txt.
350
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400351 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
352 Limit apic dumping. The parameter defines the maximal
353 number of local apics being dumped. Also it is possible
354 to set it to "all" by meaning -- no limit here.
355 Format: { 1 (default) | 2 | ... | all }.
356 The parameter valid if only apic=debug or
357 apic=verbose is specified.
358 Example: apic=debug show_lapic=all
359
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700361 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
364 Format: <io>,<irq>,<nodeID>
365
366 ataflop= [HW,M68k]
367
368 atarimouse= [HW,MOUSE] Atari Mouse
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
371 EzKey and similar keyboards
372
373 atkbd.reset= [HW] Reset keyboard during initialization
374
Randy Dunlapa9913042005-10-23 12:57:11 -0700375 atkbd.set= [HW] Select keyboard code set
376 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377
378 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
379 keyboards
380
381 atkbd.softraw= [HW] Choose between synthetic and real raw mode
382 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700383
384 atkbd.softrepeat= [HW]
385 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386
387 autotest [IA64]
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 baycom_epp= [HW,AX25]
390 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
393 Format: <io>,<mode>
394 See header of drivers/net/hamradio/baycom_par.c.
395
Randy Dunlapa9913042005-10-23 12:57:11 -0700396 baycom_ser_fdx= [HW,AX25]
397 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 Format: <io>,<irq>,<mode>[,<baud>]
399 See header of drivers/net/hamradio/baycom_ser_fdx.c.
400
Randy Dunlapa9913042005-10-23 12:57:11 -0700401 baycom_ser_hdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 Format: <io>,<irq>,<mode>
404 See header of drivers/net/hamradio/baycom_ser_hdx.c.
405
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700406 boot_delay= Milliseconds to delay each printk during boot.
407 Values larger than 10 seconds (10000) are changed to
408 no delay (0).
409 Format: integer
410
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700411 bootmem_debug [KNL] Enable bootmem allocator debug messages.
412
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700414 bttv.radio= Most important insmod options are available as
415 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
417 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
418
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000419 bulk_remove=off [PPC] This parameter disables the use of the pSeries
420 firmware feature for flushing multiple hpte entries
421 at a time.
422
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 c101= [NET] Moxa C101 synchronous serial card
424
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700425 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 Sometimes CPU hardware bugs make them report the cache
427 size incorrectly. The kernel will attempt work arounds
428 to fix known problems, but for some CPUs it is not
429 possible to determine what the correct size should be.
430 This option provides an override for these situations.
431
James Morris20510f22007-10-16 23:31:32 -0700432 capability.disable=
433 [SECURITY] Disable capabilities. This would normally
434 be used only if an alternative security model is to be
435 configured. Potentially dangerous and should only be
436 used if you are entirely sure of the consequences.
437
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100438 ccw_timeout_log [S390]
439 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440
Paul Menage8bab8dd2008-04-04 14:29:57 -0700441 cgroup_disable= [KNL] Disable a particular controller
442 Format: {name of the controller(s) to disable}
443 {Currently supported controllers - "memory"}
444
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 checkreqprot [SELINUX] Set initial checkreqprot flag value.
446 Format: { "0" | "1" }
447 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700448 0 -- check protection applied by kernel (includes
449 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 1 -- check protection requested by application.
451 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700452 Value can be changed at runtime via
453 /selinux/checkreqprot.
454
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100455 cio_ignore= [S390]
456 See Documentation/s390/CommonIO for details.
457
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700458 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700459 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200460 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700461 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200462 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 Format: { pit | tsc | cyclone | pmtmr }
464
John Stultz592913e2010-07-13 17:56:20 -0700465 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700466 Format: <string>
467 Override the default clocksource and use the clocksource
468 with the name specified.
469 Some clocksource names to choose from, depending on
470 the platform:
471 [all] jiffies (this is the base, fallback clocksource)
472 [ACPI] acpi_pm
473 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
474 pxa_timer,timer3,32k_counter,timer0_1
475 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700476 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700477 scx200_hrt on Geode; cyclone on IBM x440
478 [MIPS] MIPS
479 [PARISC] cr16
480 [S390] tod
481 [SH] SuperH
482 [SPARC64] tick
483 [X86-64] hpet,tsc
484
Andi Kleenac72e782008-01-30 13:33:21 +0100485 clearcpuid=BITNUM [X86]
486 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800487 arch/x86/include/asm/cpufeature.h for the valid bit
488 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100489 stable over kernel options, but the vendor specific
490 ones should be.
491 Also note that user programs calling CPUID directly
492 or using the feature without checking anything
493 will still see it. This just prevents it from
494 being used by the kernel or shown in /proc/cpuinfo.
495 Also note the kernel might malfunction if you disable
496 some critical bits.
497
Robert Jennings14f966e2009-04-15 05:55:32 +0000498 cmo_free_hint= [PPC] Format: { yes | no }
499 Specify whether pages are marked as being inactive
500 when they are freed. This is used in CMO environments
501 to determine OS memory pressure for page stealing by
502 a hypervisor.
503 Default: yes
504
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530505 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100506 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100507 Range: 0 - 8192
508 Default: 64
509
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700511 Format:
512 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
514 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
515 Format: <io>[,<irq>]
516
Randy Dunlapa9913042005-10-23 12:57:11 -0700517 com90xx= [HW,NET]
518 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 Format: <io>[,<irq>[,<memstart>]]
520
521 condev= [HW,S390] console device
522 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 console= [KNL] Output console device and options.
525
526 tty<n> Use the virtual console device <n>.
527
528 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800529 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800531 the form "bbbbpnf", where "bbbb" is the baud rate,
532 "p" is parity ("n", "o", or "e"), "n" is number of
533 bits, and "f" is flow control ("r" for RTS or
534 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800536 See Documentation/serial-console.txt for more
537 information. See
538 Documentation/networking/netconsole.txt for an
539 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700541 uart[8250],io,<addr>[,options]
542 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 Start an early, polled-mode console on the 8250/16550
544 UART at the specified I/O port or MMIO address,
545 switching to the matching ttyS device later. The
546 options are the same as for ttyS, above.
547
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700548 If the device connected to the port is not a TTY but a braille
549 device, prepend "brl," before the device type, for instance
550 console=brl,ttyS0
551 For now, only VisioBraille is supported.
552
Daniel Mackf324edc2009-06-16 15:33:52 -0700553 consoleblank= [KNL] The console blank (screen saver) timeout in
554 seconds. Defaults to 10*60 = 10mins. A value of 0
555 disables the blank timer.
556
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800557 coredump_filter=
558 [KNL] Change the default value for
559 /proc/<pid>/coredump_filter.
560 See also Documentation/filesystems/proc.txt.
561
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700563 Format:
564 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800566 crashkernel=size[KMG][@offset[KMG]]
567 [KNL] Using kexec, Linux can switch to a 'crash kernel'
568 upon panic. This parameter reserves the physical
569 memory region [offset, offset + size] for that kernel
570 image. If '@offset' is omitted, then a suitable offset
571 is selected automatically. Check
572 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700573
Bernhard Wallefb391592007-10-18 23:41:02 -0700574 crashkernel=range1:size1[,range2:size2,...][@offset]
575 [KNL] Same as above, but depends on the memory
576 in the running system. The syntax of range is
577 start-[end] where start and end are both
578 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800579 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 cs89x0_dma= [HW,NET]
582 Format: <dma>
583
584 cs89x0_media= [HW,NET]
585 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700586
Randy Dunlapa9913042005-10-23 12:57:11 -0700587 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 See header of drivers/s390/block/dasd_devmap.c.
589
590 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
591 (one device per port)
592 Format: <port#>,<type>
593 See also Documentation/input/joystick-parport.txt
594
Thomas Renningera648ec02010-08-06 16:11:02 +0200595 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
596 time. See Documentation/dynamic-debug-howto.txt for
597 details.
598
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 debug [KNL] Enable kernel debugging (events log level).
600
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700601 debug_locks_verbose=
602 [KNL] verbose self-tests
603 Format=<0|1>
604 Print debugging info while doing the locking API
605 self-tests.
606 We default to 0 (no extra messages), setting it to
607 1 will print _a lot_ more information - normally
608 only useful to kernel developers.
609
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700610 debug_objects [KNL] Enable object debugging
611
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500612 no_debug_objects
613 [KNL] Disable object debugging
614
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200615 debugpat [X86] Enable PAT debugging
616
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200617 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 Format: <area>[,<node>]
619 See also Documentation/networking/decnet.txt.
620
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700621 default_hugepagesz=
622 [same as hugepagesz=] The size of the default
623 HugeTLB page size. This is the size represented by
624 the legacy /proc/ hugepages APIs, used for SHM, and
625 default size when mounting hugetlbfs filesystems.
626 Defaults to the default architecture's huge page size
627 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 dhash_entries= [KNL]
630 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700631
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 digi= [HW,SERIAL]
633 IO parameters + enable/disable command.
634
635 digiepca= [HW,SERIAL]
636 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000637 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638
Brian Haleyb0f83b22010-02-04 13:36:50 -0800639 disable= [IPV6]
640 See Documentation/networking/ipv6.txt.
641
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000642 disable_ddw [PPC/PSERIES]
643 Disable Dynamic DMA Window support. Use this if
644 to workaround buggy firmware.
645
Brian Haleyb0f83b22010-02-04 13:36:50 -0800646 disable_ipv6= [IPV6]
647 See Documentation/networking/ipv6.txt.
648
Yinghai Lu95ffa242008-04-29 03:52:33 -0700649 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700650 The kernel tries to adjust MTRR layout from continuous
651 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700652 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700653
Yinghai Lu093af8d2008-01-30 13:33:32 +0100654 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100655 By default the kernel will trim any uncacheable
656 memory out of your available memory pool based on
657 MTRR settings. This parameter disables that behavior,
658 possibly causing your machine to run very slowly.
659
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530660 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700661 Disable PIN 1 of APIC timer
662 Can be useful to work around chipset bugs.
663
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700664 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
665 this option disables the debugging code at boot.
666
667 dma_debug_entries=<number>
668 This option allows to tune the number of preallocated
669 entries for DMA-API debugging code. One entry is
670 required per DMA-API allocation. Use this if the
671 DMA-API debugging code disables itself because the
672 architectural default is too low.
673
Joerg Roedel1745de52009-05-22 21:49:51 +0200674 dma_debug_driver=<driver_name>
675 With this option the DMA-API debugging driver
676 filter feature can be enabled at boot time. Just
677 pass the driver to filter for as the parameter.
678 The filter can be disabled or changed to another
679 driver later using sysfs.
680
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 dscc4.setup= [NET]
682
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700683 earlycon= [KNL] Output early console device and options.
684 uart[8250],io,<addr>[,options]
685 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700686 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700687 Start an early, polled-mode console on the 8250/16550
688 UART at the specified I/O port or MMIO address.
Samium Gromoff1917ac72010-07-20 15:26:51 -0700689 MMIO inter-register address stride is either 8bit (mmio)
690 or 32bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700691 The options are the same as for ttyS, above.
692
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530693 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 earlyprintk=vga
695 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500696 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500697 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
Randy Dunlapa9913042005-10-23 12:57:11 -0700699 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 takes over.
701
Yinghai Lu5c059172008-07-24 17:29:40 -0700702 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703
704 Currently only ttyS0 and ttyS1 are supported.
705
706 Interaction with the standard serial driver is not
707 very good.
708
709 The VGA output is eventually overwritten by the real
710 console.
711
Jason Wessel97311912010-05-20 21:04:30 -0500712 ekgdboc= [X86,KGDB] Allow early kernel console debugging
713 ekgdboc=kbd
714
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300715 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500716 the boot argument: earlyprintk=vga
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700719 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 eisa_irq_edge= [PARISC,HW]
722 See header of drivers/parisc/eisa.c.
723
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700724 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700726 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727
728 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100729 Format: {"cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700730 See Documentation/block/as-iosched.txt and
731 Documentation/block/deadline-iosched.txt for details.
732
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530733 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700734 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800735 image elf header. Generally kexec loader will
736 pass this option to capture kernel.
737 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700739 enable_mtrr_cleanup [X86]
740 The kernel tries to adjust MTRR layout from continuous
741 to discrete, to make X server driver able to add WB
742 entry later. This parameter enables that.
743
Randy Dunlapca1eda22009-05-06 16:02:58 -0700744 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700745 Enable PIN 1 of APIC timer
746 Can be useful to work around chipset bugs
747 (in particular on some ATI chipsets).
748 The kernel tries to set a reasonable default.
749
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 enforcing [SELINUX] Set initial enforcing status.
751 Format: {"0" | "1"}
752 See security/selinux/Kconfig help text.
753 0 -- permissive (log only, no denials).
754 1 -- enforcing (deny and log).
755 Default value is 0.
756 Value can be changed at runtime via /selinux/enforce.
757
Huang Yinga08f82d2010-05-18 14:35:21 +0800758 erst_disable [ACPI]
759 Disable Error Record Serialization Table (ERST)
760 support.
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 ether= [HW,NET] Ethernet cards parameters
763 This option is obsoleted by the "netdev=" option, which
764 has equivalent usage. See its documentation for details.
765
Akinobu Mitade1ba092006-12-08 02:39:42 -0800766 failslab=
767 fail_page_alloc=
768 fail_make_request=[KNL]
769 General fault injection mechanism.
770 Format: <interval>,<probability>,<space>,<times>
771 See also /Documentation/fault-injection/.
772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000774 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775
Alex Chiangf13ae302008-05-08 14:03:23 -0600776 force_pal_cache_flush
777 [IA-64] Avoid check_sal_cache_flush which may hang on
778 buggy SAL_CACHE_FLUSH implementations. Using this
779 parameter will force ia64_sal_cache_flush to call
780 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
781
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100782 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400783 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100784 as early as possible in order to facilitate early
785 boot debugging.
786
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200787 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400788 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200789 If no parameter is passed, ftrace will dump
790 buffers of all CPUs, but if you pass orig_cpu, it will
791 dump only the buffer of the CPU that triggered the
792 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400793
794 ftrace_filter=[function-list]
795 [FTRACE] Limit the functions traced by the function
796 tracer at boot up. function-list is a comma separated
797 list of functions. This list can be changed at run
798 time by the set_ftrace_filter file in the debugfs
799 tracing directory.
800
801 ftrace_notrace=[function-list]
802 [FTRACE] Do not trace the functions specified in
803 function-list. This list can be changed at run time
804 by the set_ftrace_notrace file in the debugfs
805 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100806
Stefan Assmann369bc182009-10-12 22:17:21 +0200807 ftrace_graph_filter=[function-list]
808 [FTRACE] Limit the top level callers functions traced
809 by the function graph tracer at boot up.
810 function-list is a comma separated list of functions
811 that can be changed at run time by the
812 set_graph_function file in the debugfs tracing directory.
813
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 gamecon.map[2|3]=
815 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
816 support via parallel port (up to 5 devices per port)
817 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
818 See also Documentation/input/joystick-parport.txt
819
820 gamma= [HW,DRM]
821
Yinghai Luaaf23042008-01-30 13:33:09 +0100822 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
823 Format: off | on
824 default: on
825
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700826 gcov_persist= [GCOV] When non-zero (default), profiling data for
827 kernel modules is saved and remains accessible via
828 debugfs, even when the module is unloaded/reloaded.
829 When zero, profiling data is discarded and associated
830 debugfs files are removed at module unload time.
831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 gpt [EFI] Forces disk with valid GPT signature but
833 invalid Protective MBR to be treated as GPT.
834
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 hashdist= [KNL,NUMA] Large hashes allocated during boot
836 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700837 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700838 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839
840 hcl= [IA-64] SGI's Hardware Graph compatibility layer
841
842 hd= [EIDE] (E)IDE hard drive subsystem geometry
843 Format: <cyl>,<head>,<sect>
844
Huang Yingea8c0712010-05-18 14:35:15 +0800845 hest_disable [ACPI]
846 Disable Hardware Error Source Table (HEST) support;
847 corresponding firmware-first mode error processing
848 logic will be disabled.
849
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
851 size of <nn>. This works even on boxes that have no
852 highmem otherwise. This also works to reduce highmem
853 size on bigger boxes.
854
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800855 highres= [KNL] Enable/disable high resolution timer mode.
856 Valid parameters: "on", "off"
857 Default: "on"
858
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 hisax= [HW,ISDN]
860 See Documentation/isdn/README.HiSax.
861
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700862 hlt [BUGS=ARM,SH]
863
864 hpet= [X86-32,HPET] option to control HPET usage
865 Format: { enable (default) | disable | force |
866 verbose }
867 disable: disable HPET and use PIT instead
868 force: allow force enabled of undocumented chips (ICH4,
869 VIA, nVidia)
870 verbose: show contents of HPET registers during setup
871
Andi Kleenb4718e62008-07-23 21:27:51 -0700872 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
873 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700874 On x86-64 and powerpc, this option can be specified
875 multiple times interleaved with hugepages= to reserve
876 huge pages of different sizes. Valid pages sizes on
877 x86-64 are 2M (when the CPU supports "pse") and 1G
878 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700879 Note that 1GB pages can only be allocated at boot time
880 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900881
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100882 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
883 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100884 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
885 If specified, z/VM IUCV HVC accepts connections
886 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100887
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700888 keep_bootcon [KNL]
889 Do not unregister boot console at start. This is only
890 useful for debugging when something happens in the window
891 between unregistering the boot console and initializing
892 the real console.
893
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700894 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700895 or register an additional I2C bus that is not
896 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700897 Format:
898 <bus_id>,<clkrate>
899
Jiri Kosina36d95732008-10-06 02:51:09 -0400900 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200902 i8042.dumbkbd [HW] Pretend that controller can only read data from
903 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 (Don't attempt to blink the leds)
905 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500906 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400907 i8042.noloop [HW] Disable the AUX Loopback command while probing
908 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 i8042.nomux [HW] Don't check presence of an active multiplexing
910 controller
911 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
912 controllers
Jiri Kosinaf8313ef2011-01-08 01:37:26 -0800913 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 i8042.reset [HW] Reset the controller during init and cleanup
915 i8042.unlock [HW] Unlock (ignore) the keylock
916
917 i810= [HW,DRM]
918
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700919 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
920 indicates that the driver is running on unsupported
921 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
923 does not match list of supported models.
924 i8k.power_status
925 [HW] Report power status in /proc/i8k
926 (disabled by default)
927 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
928 capability is set.
929
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 icn= [HW,ISDN]
931 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
932
David Fries0af80c02009-02-25 20:28:21 +0100933 ide-core.nodma= [HW] (E)IDE subsystem
934 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200935 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
936 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100937 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700939 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
940 Claim all unknown PCI IDE storage controllers.
941
Andi Kleenf039b752007-05-02 19:27:12 +0200942 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800943 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
944 Poll forces a polling idle loop that can slightly
945 improve the performance of waking up a idle CPU, but
946 will use a lot of power and make the system run hot.
947 Not recommended.
948 idle=mwait: On systems which support MONITOR/MWAIT but
949 the kernel chose to not use it because it doesn't save
950 as much power as a normal idle loop, use the
951 MONITOR/MWAIT idle loop anyways. Performance should be
952 the same as idle=poll.
953 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800954 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800955 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700956
Ingo Molnar792908222006-12-06 20:40:51 -0800957 ignore_loglevel [KNL]
958 Ignore loglevel setting - this will print /all/
959 kernel messages to the console. Useful for debugging.
960
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 ihash_entries= [KNL]
962 Set number of hash buckets for inode cache.
963
Mimi Zohar3323eec92009-02-04 09:06:58 -0500964 ima_audit= [IMA]
965 Format: { "0" | "1" }
966 0 -- integrity auditing messages. (Default)
967 1 -- enable informational integrity auditing messages.
968
969 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700970 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500971 default: "sha1"
972
Eric Paris5789ba32009-05-21 15:47:06 -0400973 ima_tcb [IMA]
974 Load a policy which meets the needs of the Trusted
975 Computing Base. This means IMA will measure all
976 programs exec'd, files mmap'd for exec, and all files
977 opened for read by uid=0.
978
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 init= [KNL]
980 Format: <full_path>
981 Run specified binary instead of /sbin/init as init
982 process.
983
984 initcall_debug [KNL] Trace initcalls as they are executed. Useful
985 for working out where the kernel is dying during
986 startup.
987
988 initrd= [BOOT] Specify the location of the initial ramdisk
989
990 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
991 Format: <irq>
992
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700993 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800994 on
995 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700996 off
997 Disable intel iommu driver.
998 igfx_off [Default Off]
999 By default, gfx is mapped as normal device. If a gfx
1000 device has a dedicated DMAR unit, the DMAR unit is
1001 bypassed by not enabling DMAR with this option. In
1002 this case, gfx device will use physical address for
1003 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001004 forcedac [x86_64]
1005 With this option iommu will not optimize to look
1006 for io virtual address below 32 bit forcing dual
1007 address cycle on pci bus for cards supporting greater
1008 than 32 bit addressing. The default is to look
1009 for translation below 32 bit and if not available
1010 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001011 strict [Default Off]
1012 With this option on every unmap_single operation will
1013 result in a hardware IOTLB flush operation as opposed
1014 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001015 sp_off [Default Off]
1016 By default, super page will be supported if Intel IOMMU
1017 has the capability. With this option, super page will
1018 not be supported.
Chris Wrightd1423d52010-07-20 11:06:49 -07001019 intremap= [X86-64, Intel-IOMMU]
1020 Format: { on (default) | off | nosid }
1021 on enable Interrupt Remapping (default)
1022 off disable Interrupt Remapping
1023 nosid disable Source ID checking
1024
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001025 inttest= [IA64]
1026
1027 iomem= Disable strict checking of access to MMIO memory
1028 strict regions from userspace.
1029 relaxed
1030
1031 iommu= [x86]
1032 off
1033 force
1034 noforce
1035 biomerge
1036 panic
1037 nopanic
1038 merge
1039 nomerge
1040 forcesac
1041 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001042 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001043
1044 io7= [HW] IO7 for Marvel based alpha systems
1045 See comment before marvel_specify_io7 in
1046 arch/alpha/kernel/core_marvel.c.
1047
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301048 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001049 0x80
1050 Standard port 0x80 based delay
1051 0xed
1052 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001053 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001054 Simple two microseconds delay
1055 none
1056 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001057
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001059 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060
1061 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001062 See comment before ip2_setup() in
1063 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
Alan Cox200803d2005-06-28 20:45:18 -07001065 irqfixup [HW]
1066 When an interrupt is not handled search all handlers
1067 for it. Intended to get systems with badly broken
1068 firmware running.
1069
1070 irqpoll [HW]
1071 When an interrupt is not handled search all handlers
1072 for it. Also check all handlers each timer
1073 interrupt. Intended to get systems with badly broken
1074 firmware running.
1075
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001077 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078
1079 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001080 Format:
1081 <cpu number>,...,<cpu number>
1082 or
Li Zefanb225d442008-11-06 12:53:39 -08001083 <cpu number>-<cpu number>
1084 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001085 or a mixture
1086 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001087
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 This option can be used to specify one or more CPUs
1089 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001090 algorithms. You can move a process onto or off an
1091 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 <cpu number> begins at 0 and the maximum value is
1093 "number of CPUs in system - 1".
1094
1095 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001096 alternative -- manually setting the CPU mask of all
1097 tasks in the system -- can cause problems and
1098 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
Randy Dunlapa9913042005-10-23 12:57:11 -07001100 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101
1102 js= [HW,JOY] Analog joystick
1103 See Documentation/input/joystick.txt.
1104
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001105 keepinitrd [HW,ARM]
1106
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301107 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001108 specifies the amount of memory usable by the kernel
1109 for non-movable allocations. The requested amount is
1110 spread evenly throughout all nodes in the system. The
1111 remaining memory in each node is used for Movable
1112 pages. In the event, a node is too small to have both
1113 kernelcore and Movable pages, kernelcore pages will
1114 take priority and other nodes will have a larger number
1115 of kernelcore pages. The Movable zone is used for the
1116 allocation of pages that may be reclaimed or moved
1117 by the page migration subsystem. This means that
1118 HugeTLB pages may not be allocated from this zone.
1119 Note that allocations like PTEs-from-HighMem still
1120 use the HighMem zone if it exists, and the Normal
1121 zone if it does not.
1122
Jason Wessel4fe1da42010-05-20 21:04:31 -05001123 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1124 Format: <Controller#>[,poll interval]
1125 The controller # is the number of the ehci usb debug
1126 port as it is probed via PCI. The poll interval is
1127 optional and is the number seconds in between
1128 each poll cycle to the debug port in case you need
1129 the functionality for interrupting the kernel with
1130 gdb or control-c on the dbgp connection. When
1131 not using this parameter you use sysrq-g to break into
1132 the kernel debugger.
1133
Jason Wessel84c08fd2010-05-20 21:04:24 -05001134 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001135 Requires a tty driver that supports console polling,
1136 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001137 Serial only format: <serial_device>[,baud]
1138 keyboard only format: kbd
1139 keyboard and serial format: kbd,<serial_device>[,baud]
1140 Optional Kernel mode setting:
1141 kms, kbd format: kms,kbd
1142 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001143
Jason Wessel84c08fd2010-05-20 21:04:24 -05001144 kgdbwait [KGDB] Stop kernel execution and enter the
1145 kernel debugger at the earliest opportunity.
1146
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001147 kmac= [MIPS] korina ethernet MAC address.
1148 Configure the RouterBoard 532 series on-chip
1149 Ethernet adapter MAC address.
1150
Catalin Marinas04f70332009-06-11 13:22:39 +01001151 kmemleak= [KNL] Boot-time kmemleak enable/disable
1152 Valid arguments: on, off
1153 Default: on
1154
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301155 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001156 in oops dumps.
1157
Andre Przywarafef07aa2009-07-10 14:20:35 +02001158 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1159 Default is 0 (don't ignore, but inject #GP)
1160
1161 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1162 Default is 1 (enabled)
1163
Xiao Guangronga182d872010-09-20 22:17:48 +08001164 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1165 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001166 Default is 0 (off)
1167
Andre Przywarafef07aa2009-07-10 14:20:35 +02001168 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001169 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001170
1171 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1172 for all guests.
1173 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1174
1175 kvm-intel.bypass_guest_pf=
1176 [KVM,Intel] Disables bypassing of guest page faults
1177 on Intel chips. Default is 1 (enabled)
1178
1179 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1180 (virtualized MMU) support on capable Intel chips.
1181 Default is 1 (enabled)
1182
1183 kvm-intel.emulate_invalid_guest_state=
1184 [KVM,Intel] Enable emulation of invalid guest states
1185 Default is 0 (disabled)
1186
1187 kvm-intel.flexpriority=
1188 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1189 Default is 1 (enabled)
1190
1191 kvm-intel.unrestricted_guest=
1192 [KVM,Intel] Disable unrestricted guest feature
1193 (virtualized real and unpaged mode) on capable
1194 Intel chips. Default is 1 (enabled)
1195
1196 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1197 feature (tagged TLBs) on capable Intel chips.
1198 Default is 1 (enabled)
1199
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 l2cr= [PPC]
1201
Robert Brosea78bfbf2008-03-29 07:20:23 +11001202 l3cr= [PPC]
1203
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001204 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001205 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301207 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001208 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001209
FD Camifcb71f62008-01-06 19:08:56 +01001210 libata.dma= [LIBATA] DMA control
1211 libata.dma=0 Disable all PATA and SATA DMA
1212 libata.dma=1 PATA and SATA Disk DMA only
1213 libata.dma=2 ATAPI (CDROM) DMA only
1214 libata.dma=4 Compact Flash DMA only
1215 Combinations also work, so libata.dma=3 enables DMA
1216 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001217
1218 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1219 libata.ignore_hpa=0 keep BIOS limits (default)
1220 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001221
Dave Jones78e70c22007-09-27 11:50:13 -04001222 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1223 when set.
1224 Format: <int>
1225
Tejun Heo33267322008-02-13 09:15:09 +09001226 libata.force= [LIBATA] Force configurations. The format is comma
1227 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001228 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001229 matching port, link or device. Basically, it matches
1230 the ATA ID string printed on console by libata. If
1231 the whole ID part is omitted, the last PORT and DEVICE
1232 values are used. If ID hasn't been specified yet, the
1233 configuration applies to all ports, links and devices.
1234
1235 If only DEVICE is omitted, the parameter applies to
1236 the port and all links and devices behind it. DEVICE
1237 number of 0 either selects the first device or the
1238 first fan-out link behind PMP device. It does not
1239 select the host link. DEVICE number of 15 selects the
1240 host link and device attached to it.
1241
1242 The VAL specifies the configuration to force. As long
1243 as there's no ambiguity shortcut notation is allowed.
1244 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1245 The following configurations can be forced.
1246
1247 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1248 Any ID with matching PORT is used.
1249
1250 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1251
1252 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1253 udma[/][16,25,33,44,66,100,133] notation is also
1254 allowed.
1255
1256 * [no]ncq: Turn on or off NCQ.
1257
Tejun Heo05944bd2008-08-13 20:19:09 +09001258 * nohrst, nosrst, norst: suppress hard, soft
1259 and both resets.
1260
Tejun Heo43c9c592010-05-23 12:59:11 +02001261 * dump_id: dump IDENTIFY data.
1262
Tejun Heo33267322008-02-13 09:15:09 +09001263 If there are multiple matching configurations changing
1264 the same attribute, the last one is used.
1265
Yinghai Lu95f72d12010-07-12 14:36:09 +10001266 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001267
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001269 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001271 lockd.nlm_grace_period=P [NFS] Assign grace period.
1272 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001274 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1275 Format: <integer>
1276
1277 lockd.nlm_timeout=T [NFS] Assign timeout value.
1278 Format: <integer>
1279
1280 lockd.nlm_udpport=M [NFS] Assign UDP port.
1281 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282
1283 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1284 Format: <irq>
1285
1286 loglevel= All Kernel Messages with a loglevel smaller than the
1287 console loglevel will be printed to the console. It can
1288 also be changed with klogd or other programs. The
1289 loglevels are defined as follows:
1290
1291 0 (KERN_EMERG) system is unusable
1292 1 (KERN_ALERT) action must be taken immediately
1293 2 (KERN_CRIT) critical conditions
1294 3 (KERN_ERR) error conditions
1295 4 (KERN_WARNING) warning conditions
1296 5 (KERN_NOTICE) normal but significant condition
1297 6 (KERN_INFO) informational
1298 7 (KERN_DEBUG) debug-level messages
1299
Randy Dunlapc756d082011-02-20 20:08:35 -08001300 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1301 in bytes. n must be a power of two. The default
1302 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
Randy Dunlapaccaa242007-10-16 01:29:37 -07001304 logo.nologo [FB] Disables display of the built-in Linux logo.
1305 This may be used to provide more screen space for
1306 kernel log messages and is useful when debugging
1307 kernel boot problems.
1308
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 lp=0 [LP] Specify parallel ports to use, e.g,
1310 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1311 lp=reset first parallel port). 'lp=0' disables the
1312 lp=auto printer driver. 'lp=reset' (which can be
1313 specified in addition to the ports) causes
1314 attached printers to be reset. Using
1315 lp=port1,port2,... specifies the parallel ports
1316 to associate lp devices with, starting with
1317 lp0. A port specification may be 'none' to skip
1318 that lp device, or a parport name such as
1319 'parport0'. Specifying 'lp=auto' instead of a
1320 port specification list means that device IDs
1321 from each port should be examined, to see if
1322 an IEEE 1284-compliant printer is attached; if
1323 so, the driver will manage that printer.
1324 See also header of drivers/char/lp.c.
1325
1326 lpj=n [KNL]
1327 Sets loops_per_jiffy to given constant, thus avoiding
1328 time-consuming boot-time autodetection (up to 250 ms per
1329 CPU). 0 enables autodetection (default). To determine
1330 the correct value for your kernel, boot with normal
1331 autodetection and see what value is printed. Note that
1332 on SMP systems the preset will be applied to all CPUs,
1333 which is likely to cause problems if your CPUs need
1334 significantly divergent settings. An incorrect value
1335 will cause delays in the kernel to be wrong, leading to
1336 unpredictable I/O errors and other breakage. Although
1337 unlikely, in the extreme case this might damage your
1338 hardware.
1339
1340 ltpc= [NET]
1341 Format: <io>,<irq>,<dma>
1342
Randy Dunlapa9913042005-10-23 12:57:11 -07001343 machvec= [IA64] Force the use of a particular machine-vector
1344 (machvec) in a generic kernel.
1345 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346
Wu Zhangjin3209e702009-07-02 23:27:12 +08001347 machtype= [Loongson] Share the same kernel image file between different
1348 yeeloong laptop.
1349 Example: machtype=lemote-yeeloong-2f-7inch
1350
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001351 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1352 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
1354 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001355 should make use of. maxcpus=n : n >= 0 limits the
1356 kernel to using 'n' processors. n=0 is a special case,
1357 it is equivalent to "nosmp", which also disables
1358 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001360 max_loop= [LOOP] Maximum number of loopback devices that can
1361 be mounted
1362 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001363
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 mcatest= [IA-64]
1365
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001366 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367
Uwe Hermann71cced62008-10-20 09:32:21 -07001368 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001369
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 md= [HW] RAID subsystems devices and level
1371 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001372
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 mdacon= [MDA]
1374 Format: <first>,<last>
1375 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1378 Amount of memory to be used when the kernel is not able
1379 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001380 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 address space collisions. Without memmap= PCI devices
1382 could be placed at addresses belonging to unused RAM.
1383
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001384 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 memory.
1386
Paul Mundt6902aa82008-09-21 17:14:42 +09001387 memchunk=nn[KMG]
1388 [KNL,SH] Allow user to override the default size for
1389 per-device physically contiguous DMA buffers.
1390
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301391 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 E820 memory map, as specified by the user.
1393 Such memmap=exactmap lines can be constructed based on
1394 BIOS output or other requirements. See the memmap=nn@ss
1395 option description.
1396
1397 memmap=nn[KMG]@ss[KMG]
1398 [KNL] Force usage of a specific region of memory
1399 Region of memory to be used, from ss to ss+nn.
1400
1401 memmap=nn[KMG]#ss[KMG]
1402 [KNL,ACPI] Mark specific memory as ACPI data.
1403 Region of memory to be used, from ss to ss+nn.
1404
1405 memmap=nn[KMG]$ss[KMG]
1406 [KNL,ACPI] Mark specific memory as reserved.
1407 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001408 Example: Exclude memory from 0x18690000-0x1869ffff
1409 memmap=64K$0x18690000
1410 or
1411 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001413 memory_corruption_check=0/1 [X86]
1414 Some BIOSes seem to corrupt the first 64k of
1415 memory when doing things like suspend/resume.
1416 Setting this option will scan the memory
1417 looking for corruption. Enabling this will
1418 both detect corruption and prevent the kernel
1419 from using the memory being corrupted.
1420 However, its intended as a diagnostic tool; if
1421 repeatable BIOS-originated corruption always
1422 affects the same memory, you can use memmap=
1423 to prevent the kernel from using that memory.
1424
1425 memory_corruption_check_size=size [X86]
1426 By default it checks for corruption in the low
1427 64k, making this memory unavailable for normal
1428 use. Use this parameter to scan for
1429 corruption in more or less memory.
1430
1431 memory_corruption_check_period=seconds [X86]
1432 By default it checks for corruption every 60
1433 seconds. Use this parameter to check at some
1434 other rate. 0 disables periodic checking.
1435
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001436 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001437 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001438 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001439 Specifies the number of memtest passes to be
1440 performed. Each pass selects another test
1441 pattern from a given set of patterns. Memtest
1442 fills the memory with this pattern, validates
1443 memory contents and reserves bad memory
1444 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001445
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446 meye.*= [HW] Set MotionEye Camera parameters
1447 See Documentation/video4linux/meye.txt.
1448
Andres Salomon8f368812007-10-12 23:04:06 +02001449 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1450 Multi-Function General Purpose Timers on AMD Geode
1451 platforms.
1452
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001453 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1454 the BIOS has incorrectly applied a workaround. TinyBIOS
1455 version 0.98 is known to be affected, 0.99 fixes the
1456 problem by letting the user disable the workaround.
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 mga= [HW,DRM]
1459
Randy Dunlap1c207f92008-11-19 15:36:16 -08001460 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1461 physical address is ignored.
1462
Michel Pollet39f45d72009-05-20 11:10:31 +01001463 mini2440= [ARM,HW,KNL]
1464 Format:[0..2][b][c][t]
1465 Default: "0tb"
1466 MINI2440 configuration specification:
1467 0 - The attached screen is the 3.5" TFT
1468 1 - The attached screen is the 7" TFT
1469 2 - The VGA Shield is attached (1024x768)
1470 Leaving out the screen size parameter will not load
1471 the TFT driver, and the framebuffer will be left
1472 unconfigured.
1473 b - Enable backlight. The TFT backlight pin will be
1474 linked to the kernel VESA blanking code and a GPIO
1475 LED. This parameter is not necessary when using the
1476 VGA shield.
1477 c - Enable the s3c camera interface.
1478 t - Reserved for enabling touchscreen support. The
1479 touchscreen support is not enabled in the mainstream
1480 kernel as of 2.6.30, a preliminary port can be found
1481 in the "bleeding edge" mini2440 support kernel at
1482 http://repo.or.cz/w/linux-2.6/mini2440.git
1483
Mel Gorman6b74ab92008-07-23 21:26:49 -07001484 mminit_loglevel=
1485 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1486 parameter allows control of the logging verbosity for
1487 the additional memory initialisation checks. A value
1488 of 0 disables mminit logging and a level of 4 will
1489 log everything. Information is printed at KERN_DEBUG
1490 so loglevel=8 may also need to be specified.
1491
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 mousedev.tap_time=
1493 [MOUSE] Maximum time between finger touching and
1494 leaving touchpad surface for touch to be considered
1495 a tap and be reported as a left button click (for
1496 touchpads working in absolute mode only).
1497 Format: <msecs>
1498 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1499 reporting absolute coordinates, such as tablets
1500 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1501 reporting absolute coordinates, such as tablets
1502
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301503 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001504 is similar to kernelcore except it specifies the
1505 amount of memory used for migratable allocations.
1506 If both kernelcore and movablecore is specified,
1507 then kernelcore will be at *least* the specified
1508 value but may be more. If movablecore on its own
1509 is specified, the administrator must be careful
1510 that the amount of memory usable for all allocations
1511 is not too small.
1512
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513 MTD_Partition= [MTD]
1514 Format: <name>,<region-number>,<size>,<offset>
1515
Randy Dunlapa9913042005-10-23 12:57:11 -07001516 MTD_Region= [MTD] Format:
1517 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518
1519 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001520 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001522 multitce=off [PPC] This parameter disables the use of the pSeries
1523 firmware feature for updating multiple TCE entries
1524 at a time.
1525
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001526 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1527
1528 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1529
1530 boundary - index of last SLC block on Flex-OneNAND.
1531 The remaining blocks are configured as MLC blocks.
1532 lock - Configure if Flex-OneNAND boundary should be locked.
1533 Once locked, the boundary cannot be changed.
1534 1 indicates lock status, 0 indicates unlock status.
1535
Ben Dooks9db829f2008-07-03 11:24:29 +01001536 mtdset= [ARM]
1537 ARM/S3C2412 JIVE boot control
1538
1539 See arch/arm/mach-s3c2412/mach-jive.c
1540
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001542 [HW] Make the MicroTouch USB driver use raw coordinates
1543 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001545 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001546 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001547 that could hold holes aka. UC entries.
1548
1549 mtrr_gran_size=nn[KMG] [X86]
1550 Used for mtrr cleanup. It is granularity of mtrr block.
1551 Default is 1.
1552 Large value could prevent small alignment from
1553 using up MTRRs.
1554
1555 mtrr_spare_reg_nr=n [X86]
1556 Format: <integer>
1557 Range: 0,7 : spare reg number
1558 Default : 1
1559 Used for mtrr cleanup. It is spare mtrr entries number.
1560 Set to 2 or more if your graphical card needs more.
1561
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1563
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 netdev= [NET] Network devices parameters
1565 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1566 Note that mem_start is often overloaded to mean
1567 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001568 This usage is only documented in each driver source
1569 file if at all.
1570
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001571 nf_conntrack.acct=
1572 [NETFILTER] Enable connection tracking flow accounting
1573 0 to disable accounting
1574 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001575 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001576
Chuck Lever306a0752010-09-17 10:54:37 -04001577 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001578 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
1580 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001581 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582
Chuck Lever306a0752010-09-17 10:54:37 -04001583 nfsrootdebug [NFS] enable nfsroot debugging messages.
1584 See Documentation/filesystems/nfs/nfsroot.txt.
1585
Trond Myklebusta72b4422006-01-03 09:55:41 +01001586 nfs.callback_tcpport=
1587 [NFS] set the TCP port on which the NFSv4 callback
1588 channel should listen.
1589
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001590 nfs.cache_getent=
1591 [NFS] sets the pathname to the program which is used
1592 to update the NFS client cache entries.
1593
1594 nfs.cache_getent_timeout=
1595 [NFS] sets the timeout after which an attempt to
1596 update a cache entry is deemed to have failed.
1597
Trond Myklebust58df0952006-01-03 09:55:57 +01001598 nfs.idmap_cache_timeout=
1599 [NFS] set the maximum lifetime for idmapper cache
1600 entries.
1601
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001602 nfs.enable_ino64=
1603 [NFS] enable 64-bit inode numbers.
1604 If zero, the NFS client will fake up a 32-bit inode
1605 number for the readdir() and stat() syscalls instead
1606 of returning the full 64-bit number.
1607 The default is to return 64-bit inode numbers.
1608
Trond Myklebustb064eca22011-02-22 15:44:32 -08001609 nfs.nfs4_disable_idmapping=
1610 [NFSv4] When set, this option disables the NFSv4
1611 idmapper on the client, but only if the mount
1612 is using the 'sec=sys' security flavour. This may
1613 make migration from legacy NFSv2/v3 systems easier
1614 provided that the server has the appropriate support.
1615 The default is to always enable NFSv4 idmapping.
1616
Paul Mundt1e1030d2009-09-01 17:38:32 +09001617 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001618 when a NMI is triggered.
1619 Format: [state][,regs][,debounce][,die]
1620
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301621 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001622 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001623 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001624 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001625 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001626 timeout occurs (or 'nopanic' to override the opposite
1627 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001628 This is useful when you use a panic=... timeout and
1629 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630
Anton Vorontsovbff38772009-07-08 11:10:56 -07001631 netpoll.carrier_timeout=
1632 [NET] Specifies amount of time (in seconds) that
1633 netpoll should wait for a carrier. By default netpoll
1634 waits 4 seconds.
1635
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001636 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 emulation library even if a 387 maths coprocessor
1638 is present.
1639
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001640 no_console_suspend
1641 [HW] Never suspend the console
1642 Disable suspending of consoles during suspend and
1643 hibernate operations. Once disabled, debugging
1644 messages can reach various consoles while the rest
1645 of the system is being put to sleep (ie, while
1646 debugging driver suspend/resume hooks). This may
1647 not work reliably with all consoles, but is known
1648 to work with serial and VGA consoles.
1649
Christoph Lameterc1aee212007-05-31 00:40:47 -07001650 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1651 caches in the slab allocator. Saves per-node memory,
1652 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001653
Randy Dunlapa9913042005-10-23 12:57:11 -07001654 noalign [KNL,ARM]
1655
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656 noapic [SMP,APIC] Tells the kernel to not make use of any
1657 IOAPICs that may be present in the system.
1658
Mike Galbraith5091faa2010-11-30 14:18:03 +01001659 noautogroup Disable scheduler automatic task group creation.
1660
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 nobats [PPC] Do not use BATs for mapping kernel lowmem
1662 on "Classic" PPC cores.
1663
1664 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001665
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001666 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1667
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001668 nodelayacct [KNL] Disable per-task delay accounting
1669
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1671
Paul Mundt6902aa82008-09-21 17:14:42 +09001672 nodsp [SH] Disable hardware DSP at boot time.
1673
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301674 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001675
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 noexec [IA-64]
1677
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301678 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001679 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001681 noexec=off: disable non-executable mappings
1682
Fenghua Yude5397a2011-05-11 16:51:05 -07001683 nosmep [X86]
1684 Disable SMEP (Supervisor Mode Execution Protection)
1685 even if it is supported by processor.
1686
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001687 noexec32 [X86-64]
1688 This affects only 32-bit executables.
1689 noexec32=on: enable non-executable mappings (default)
1690 read doesn't imply executable mappings
1691 noexec32=off: disable non-executable mappings
1692 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693
Paul Mundt6902aa82008-09-21 17:14:42 +09001694 nofpu [SH] Disable hardware FPU at boot time.
1695
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001696 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001697 register save and restore. The kernel will only save
1698 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699
Suresh Siddha0c752a92009-05-22 12:17:45 -07001700 noxsave [BUGS=X86] Disables x86 extended register state save
1701 and restore using xsave. The kernel will fallback to
1702 enabling legacy floating-point and sse state.
1703
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001704 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1705 wfi(ARM) instruction doesn't work correctly and not to
1706 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001707
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001708 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 instruction doesn't work correctly and not to
1710 use it.
1711
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001712 no_file_caps Tells the kernel not to honor file capabilities. The
1713 only way then for a file to be executed with privilege
1714 is to be setuid root or executed by root.
1715
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 nohalt [IA-64] Tells the kernel not to use the power saving
1717 function PAL_HALT_LIGHT when idle. This increases
1718 power-consumption. On the positive side, it reduces
1719 interrupt wake-up latency, which may improve performance
1720 in certain environments such as networked servers or
1721 real-time systems.
1722
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001723 nohz= [KNL] Boottime enable/disable dynamic ticks
1724 Valid arguments: on, off
1725 Default: on
1726
Paul Mundteeee7852009-04-02 12:31:16 +09001727 noiotrap [SH] Disables trapped I/O port accesses.
1728
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001729 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 disable unhandled interrupt sources.
1731
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301732 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001733 broken timer IRQ sources.
1734
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 noisapnp [ISAPNP] Disables ISA PnP code.
1736
1737 noinitrd [RAM] Tells the kernel not to load any configured
1738 initial RAM disk.
1739
Weidong Han03ea8152009-04-17 16:42:15 +08001740 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1741 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001742 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 nointroute [IA-64]
1745
Tony Luck0aa366f2007-07-20 11:22:30 -07001746 nojitter [IA64] Disables jitter checking for ITC timers.
1747
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001748 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1749
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001750 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1751 fault handling.
1752
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001753 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001755 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001756
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 noltlbs [PPC] Do not use large page/tlb entries for kernel
1758 lowmem mapping on PPC40x.
1759
Horms312f1f02006-02-22 09:57:55 +09001760 nomca [IA-64] Disable machine check abort handling
1761
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001762 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001763
Andres Salomon83d73842007-10-12 23:04:06 +02001764 nomfgpt [X86-32] Disable Multi-Function General Purpose
1765 Timer usage (for AMD Geode machines).
1766
Jiri Kosina016ddd92010-01-18 17:05:40 +01001767 nopat [X86] Disable PAT (page attribute table extension of
1768 pagetables) support.
1769
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001770 norandmaps Don't use address space randomization. Equivalent to
1771 echo 0 > /proc/sys/kernel/randomize_va_space
1772
Jiri Kosinabbff2162010-08-11 18:34:09 +02001773 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001774
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001775 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001776 with UP alternatives
1777
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 noresidual [PPC] Don't use residual data on PReP machines.
1779
Randy Dunlapa9913042005-10-23 12:57:11 -07001780 noresume [SWSUSP] Disables resume and restores original swap
1781 space.
1782
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 no-scroll [VGA] Disables scrollback.
1784 This is required for the Braillex ib80-piezo Braille
1785 reader made by F.H. Papenmeier (Germany).
1786
1787 nosbagart [IA-64]
1788
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001789 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001790
Len Brown61ec7562007-08-16 03:34:22 -04001791 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1792 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793
Dave Jones97842212007-07-15 23:41:05 -07001794 nosoftlockup [KNL] Disable the soft-lockup detector.
1795
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 nosync [HW,M68K] Disables sync negotiation for all devices.
1797
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001798 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799
1800 nousb [USB] Disable the USB subsystem
1801
Ben Hutchings55142372011-01-02 23:02:42 +00001802 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001803
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001805
Weidong Han2b2fd872009-04-17 16:42:12 +08001806 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1807
Fenghua Yua6c75b862008-03-14 13:57:08 -07001808 nptcg= [IA64] Override max number of concurrent global TLB
1809 purges which is reported from either PAL_VM_SUMMARY or
1810 SAL PALO.
1811
Yinghai Lu2b633e32010-02-10 01:20:37 -08001812 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1813 could support. nr_cpus=n : n >= 1 limits the kernel to
1814 supporting 'n' processors. Later in runtime you can not
1815 use hotplug cpu feature to put more cpu back to online.
1816 just like you compile the kernel NR_CPUS=n
1817
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001818 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1819
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001820 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1821 one of ['zone', 'node', 'default'] can be specified
1822 This can be set from sysctl after boot.
1823 See Documentation/sysctl/vm.txt for details.
1824
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001825 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1826 See Documentation/debugging-via-ohci1394.txt for more
1827 info.
1828
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001829 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1830 Rather than timing out after 20 ms if an EC
1831 command is not properly ACKed, override the length
1832 of the timeout. We have interrupts disabled while
1833 waiting for the ACK, so if this is set too high
1834 interrupts *may* be lost!
1835
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001836 omap_mux= [OMAP] Override bootloader pin multiplexing.
1837 Format: <mux_mode0.mode_name=value>...
1838 For example, to override I2C bus2:
1839 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1840
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 oprofile.timer= [HW]
1842 Use timer interrupt instead of performance counters
1843
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001844 oprofile.cpu_type= Force an oprofile cpu type
1845 This might be useful if you have an older oprofile
1846 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001847 Format: { arch_perfmon }
1848 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001849 perfmon on Intel CPUs instead of the
1850 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001851
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001852 oops=panic Always panic on oopses. Default is to just kill the
1853 process, but there is a small probability of
1854 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07001855 This will also cause panics on machine check exceptions.
1856 Useful together with panic=30 to trigger a reboot.
1857
Randy Dunlapbcfde332010-06-07 17:10:38 -07001858 OSS [HW,OSS]
1859 See Documentation/sound/oss/oss-parameters.txt
1860
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001861 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1862 seconds before rebooting
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 Format: <timeout>
1864
1865 parkbd.port= [HW] Parallel port number the keyboard adapter is
1866 connected to, default is 0.
1867 Format: <parport#>
1868 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1869 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001870 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871
Randy Dunlapa9913042005-10-23 12:57:11 -07001872 parport= [HW,PPT] Specify parallel ports. 0 disables.
1873 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1874 Use 'auto' to force the driver to use any
1875 IRQ/DMA settings detected (the default is to
1876 ignore detected IRQ/DMA settings because of
1877 possible conflicts). You can specify the base
1878 address, IRQ, and DMA settings; IRQ and DMA
1879 should be numbers, or 'auto' (for using detected
1880 settings on that particular port), or 'nofifo'
1881 (to avoid using a FIFO even if it is detected).
1882 Parallel ports are assigned in the order they
1883 are specified on the command line, starting
1884 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885
Randy Dunlapa9913042005-10-23 12:57:11 -07001886 parport_init_mode= [HW,PPT]
1887 Configure VIA parallel port to operate in
1888 a specific mode. This is necessary on Pegasos
1889 computer where firmware has no options for setting
1890 up parallel port mode and sets it to spp.
1891 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 Format: [spp|ps2|epp|ecp|ecpepp]
1893
Andrew Mortondd287792006-03-23 03:00:57 -08001894 pause_on_oops=
1895 Halt all CPUs after the first oops has been printed for
1896 the specified number of seconds. This is to be used if
1897 your oopses keep scrolling off the screen.
1898
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 pcbit= [HW,ISDN]
1900
1901 pcd. [PARIDE]
1902 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001903 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904
Randy Dunlapa9913042005-10-23 12:57:11 -07001905 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001906 earlydump [X86] dump PCI config space before the kernel
1907 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001908 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001909 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001910 the hardware directly. Use this if your machine
1911 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001912 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001913 hardware access methods are allowed. Use this
1914 if you experience crashes upon bootup and you
1915 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001916 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001917 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001918 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001919 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001920 noaer [PCIE] If the PCIEAER kernel config parameter is
1921 enabled, this kernel boot option can be used to
1922 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001923 nodomains [PCI] Disable support for multiple PCI
1924 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301925 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001926 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001927 check_enable_amd_mmconf [X86] check for and enable
1928 properly configured MMIO access to PCI
1929 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001930 nomsi [MSI] If the PCI_MSI kernel config parameter is
1931 enabled, this kernel boot option can be used to
1932 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001933 noioapicquirk [APIC] Disable all boot interrupt quirks.
1934 Safety option to keep boot IRQs enabled. This
1935 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001936 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1937 primary IO-APIC for bridges that cannot disable
1938 boot IRQs. This fixes a source of spurious IRQs
1939 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001940 noioapicreroute [APIC] Disable workaround that uses the
1941 boot IRQ equivalent of an IRQ that connects to
1942 a chipset where boot IRQs cannot be disabled.
1943 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001944 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001945 routing table. These calls are known to be buggy
1946 on several machines and they hang the machine
1947 when used, but on other computers it's the only
1948 way to get the interrupt routing table. Try
1949 this option if the kernel is unable to allocate
1950 IRQs or discover secondary PCI buses on your
1951 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001952 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001953 Use with caution as certain devices share
1954 address decoders between ROMs and other
1955 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001956 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001957 expansion ROMs that do not already have
1958 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07001959 nobar [X86] Do not assign address space to the
1960 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001961 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001962 assigned automatically to PCI devices. You can
1963 make the kernel exclude IRQs of your ISA cards
1964 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001965 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001966 of the PIRQ table (normally generated
1967 by the BIOS) if it is outside the
1968 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001969 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001970 useful if the kernel is unable to find your
1971 secondary buses and you want to tell it
1972 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001973 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001974 numbers ourselves, overriding
1975 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001976 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001977 in the BIOS $PIR table. This is needed on
1978 some systems with broken BIOSes, notably
1979 some HP Pavilion N5400 and Omnibook XE3
1980 notebooks. This will have no effect if ACPI
1981 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001982 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001983 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001984 use_crs [X86] Use PCI host bridge window information
1985 from ACPI. On BIOSes from 2008 or later, this
1986 is enabled by default. If you need to use this,
1987 please report a bug.
1988 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1989 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001990 routeirq Do IRQ routing for all PCI devices.
1991 This is normally done in pci_enable_device(),
1992 so this option is a temporary workaround
1993 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001994 skip_isa_align [X86] do not align io start addr, so can
1995 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001996 firmware [ARM] Do not re-enumerate the bus but instead
1997 just use the configuration from the
1998 bootloader. This is currently used on
1999 IXP2000 systems where the bus has to be
2000 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002001 noearly [X86] Don't do any early type 1 scanning.
2002 This might help on some broken boards which
2003 machine check when some devices' config space
2004 is read. But various workarounds are disabled
2005 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002006 bfsort Sort PCI devices into breadth-first order.
2007 This sorting is done to get a device
2008 order compatible with older (<= 2.4) kernels.
2009 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002010 cbiosize=nn[KMG] The fixed amount of bus space which is
2011 reserved for the CardBus bridge's IO window.
2012 The default value is 256 bytes.
2013 cbmemsize=nn[KMG] The fixed amount of bus space which is
2014 reserved for the CardBus bridge's memory
2015 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002016 resource_alignment=
2017 Format:
2018 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2019 Specifies alignment and device to reassign
2020 aligned memory resources.
2021 If <order of align> is not specified,
2022 PAGE_SIZE is used as alignment.
2023 PCI-PCI bridge can be specified, if resource
2024 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002025 ecrc= Enable/disable PCIe ECRC (transaction layer
2026 end-to-end CRC checking).
2027 bios: Use BIOS/firmware settings. This is the
2028 the default.
2029 off: Turn ECRC off
2030 on: Turn ECRC on.
Ram Paif483d392011-07-07 11:19:10 -07002031 realloc reallocate PCI resources if allocations done by BIOS
2032 are erroneous.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002033
Chuck Ebberte5665a42008-09-24 20:40:34 -04002034 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2035 Management.
2036 off Disable ASPM.
2037 force Enable ASPM even on devices that claim not to support it.
2038 WARNING: Forcing ASPM on may cause system lockups.
2039
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002040 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002041 auto Ask the BIOS whether or not to use native PCIe services
2042 associated with PCIe ports (PME, hot-plug, AER). Use
2043 them only if that is allowed by the BIOS.
2044 native Use native PCIe services associated with PCIe ports
2045 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002046 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2047 ports driver.
2048
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002049 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002050 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002051 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002052
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 pcmv= [HW,PCMCIA] BadgePAD 4
2054
2055 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002056 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057
2058 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2059 boot time.
2060 Format: { 0 | 1 }
2061 See arch/parisc/kernel/pdc_chassis.c
2062
Tejun Heof58dc012009-08-14 15:00:50 +09002063 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002064 Currently supported values are "embed" and "page".
2065 Archs may support subset or none of the selections.
2066 See comments in mm/percpu.c for details on each
2067 allocator. This parameter is primarily for debugging
2068 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002071 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072
2073 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002074 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075
2076 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002077 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078
2079 plip= [PPT,NET] Parallel port network link
2080 Format: { parport<nr> | timid | 0 }
2081 See also Documentation/parport.txt.
2082
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002083 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2084 Override pmtimer IOPort with a hex value.
2085 e.g. pmtmr=0x508
2086
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002087 pnp.debug [PNP]
2088 Enable PNP debug messages. This depends on the
2089 CONFIG_PNP_DEBUG_MESSAGES option.
2090
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 pnpacpi= [ACPI]
2092 { off }
2093
2094 pnpbios= [ISAPNP]
2095 { on | off | curr | res | no-curr | no-res }
2096
2097 pnp_reserve_irq=
2098 [ISAPNP] Exclude IRQs for the autoconfiguration
2099
2100 pnp_reserve_dma=
2101 [ISAPNP] Exclude DMAs for the autoconfiguration
2102
2103 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002104 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105
2106 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002107 [ISAPNP] Exclude memory regions for the
2108 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 Ranges are in pairs (memory base and size).
2110
Randy Dunlap4af94f32009-04-17 18:30:28 -07002111 ports= [IP_VS_FTP] IPVS ftp helper module
2112 Default is 21.
2113 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2114 may be specified.
2115 Format: <port>,<port>....
2116
Ingo Molnar45807a12007-07-15 23:40:10 -07002117 print-fatal-signals=
2118 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002119
2120 If enabled, warn about various signal handling
2121 related application anomalies: too many signals,
2122 too many POSIX.1 timers, fatal signals causing a
2123 coredump - etc.
2124
2125 If you hit the warning due to signal overflow,
2126 you might want to try "ulimit -i unlimited".
2127
Ingo Molnar45807a12007-07-15 23:40:10 -07002128 default: off.
2129
Randy Dunlape84845c2007-07-15 23:40:25 -07002130 printk.time= Show timing data prefixed to each printk message line
2131 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2132
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002133 processor.max_cstate= [HW,ACPI]
2134 Limit processor to maximum C-state
2135 max_cstate=9 overrides any DMI blacklist limit.
2136
2137 processor.nocst [HW,ACPI]
2138 Ignore the _CST method to determine C-states,
2139 instead using the legacy FADT method
2140
Linus Torvalds1da177e2005-04-16 15:20:36 -07002141 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002142 Format: [schedule,]<number>
2143 Param: "schedule" - profile schedule points.
2144 Param: <number> - step/bucket size as a power of 2 for
2145 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002146 Param: "sleep" - profile D-state sleeping (millisecs).
2147 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002148 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2151 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002152 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
Randy Dunlapa9913042005-10-23 12:57:11 -07002154 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2155 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2157 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002158 psmouse.resetafter= [HW,MOUSE]
2159 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 (0 = never).
2161 psmouse.resolution=
2162 [HW,MOUSE] Set desired mouse resolution, in dpi.
2163 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002164 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 0 = disabled, 1 = enabled (default).
2166
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002168 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169
Kay Sieversdc8c8582007-08-15 12:25:38 +02002170 pty.legacy_count=
2171 [KNL] Number of legacy pty's. Overwrites compiled-in
2172 default number.
2173
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002174 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002175
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176 r128= [HW,DRM]
2177
2178 raid= [HW,RAID]
2179 See Documentation/md.txt.
2180
Randy Dunlapa9913042005-10-23 12:57:11 -07002181 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002182 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002183
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002185 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002187 rcupdate.blimit= [KNL,BOOT]
2188 Set maximum number of finished RCU callbacks to process
2189 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002190
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002191 rcupdate.qhimark= [KNL,BOOT]
2192 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002193 RCU callbacks over which batch limiting is disabled.
2194
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002195 rcupdate.qlowmark= [KNL,BOOT]
2196 Set threshold of queued RCU callbacks below which
2197 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002198
Olof Johanssonffdfc402005-09-06 15:17:19 -07002199 rdinit= [KNL]
2200 Format: <full_path>
2201 Run specified binary instead of /init from the ramdisk,
2202 used for early userspace startup. See initrd.
2203
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002204 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002206 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207
Paul Jackson46b6d942008-07-04 10:00:09 -07002208 relax_domain_level=
2209 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002210 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002211
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2213
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002214 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002215 Format: nn[KMG]
2216 Reserves a hole at the top of the kernel virtual
2217 address space.
2218
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002219 reservelow= [X86]
2220 Format: nn[K]
2221 Set the amount of memory to reserve for BIOS at
2222 the bottom of the address space.
2223
Vivek Goyal7e962872006-09-27 01:50:44 -07002224 reset_devices [KNL] Force drivers to reset the underlying device
2225 during initialization.
2226
Randy Dunlapa9913042005-10-23 12:57:11 -07002227 resume= [SWSUSP]
2228 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002230 resume_offset= [SWSUSP]
2231 Specify the offset from the beginning of the partition
2232 given by "resume=" at which the swap header is located,
2233 in <PAGE_SIZE> units (needed only for swap files).
2234 See Documentation/power/swsusp-and-swap-files.txt
2235
Bojan Smojverf996fc92010-09-09 23:06:23 +02002236 hibernate= [HIBERNATION]
2237 noresume Don't check if there's a hibernation image
2238 present during boot.
2239 nocompress Don't compress/decompress hibernation images.
2240
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002241 retain_initrd [RAM] Keep initrd memory after extraction
2242
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243 rhash_entries= [KNL,NET]
2244 Set number of hash buckets for route cache
2245
2246 riscom8= [HW,SERIAL]
2247 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2248
2249 ro [KNL] Mount root device read-only on boot
2250
2251 root= [KNL] Root filesystem
2252
2253 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2254 mount the root filesystem
2255
2256 rootflags= [KNL] Set root filesystem mount option string
2257
2258 rootfstype= [KNL] Set root filesystem type
2259
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002260 rootwait [KNL] Wait (indefinitely) for root device to show up.
2261 Useful for devices that are detected asynchronously
2262 (e.g. USB and MMC devices).
2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 rw [KNL] Mount root device read-write on boot
2265
2266 S [KNL] Run init in single mode
2267
2268 sa1100ir [NET]
2269 See drivers/net/irda/sa1100_ir.c.
2270
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002272
Mike Travisf6630112009-11-17 18:22:15 -06002273 sched_debug [KNL] Enables verbose scheduler debug messages.
2274
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002275 security= [SECURITY] Choose a security module to enable at boot.
2276 If this boot parameter is not specified, only the first
2277 security module asking for security registration will be
2278 loaded. An invalid security module name will be treated
2279 as if no module has been chosen.
2280
2281 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282 Format: { "0" | "1" }
2283 See security/selinux/Kconfig help text.
2284 0 -- disable.
2285 1 -- enable.
2286 Default value is set via kernel config option.
2287 If enabled at boot time, /selinux/disable can be used
2288 later to disable prior to initial policy load.
2289
John Johansenc1c124e2010-07-29 14:48:09 -07002290 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2291 Format: { "0" | "1" }
2292 See security/apparmor/Kconfig help text
2293 0 -- disable.
2294 1 -- enable.
2295 Default value is set via kernel config option.
2296
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002297 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299 shapers= [NET]
2300 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002301
Yinghai Lub05f78f2008-08-22 01:32:50 -07002302 show_msr= [x86] show boot-time MSR settings
2303 Format: { <integer> }
2304 Show boot-time (BIOS-initialized) MSR settings.
2305 The parameter means the number of CPUs to show,
2306 for example 1 means boot CPU only.
2307
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 simeth= [IA-64]
2309 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002310
Linus Torvalds1da177e2005-04-16 15:20:36 -07002311 slram= [HW,MTD]
2312
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002313 slub_debug[=options[,slabs]] [MM, SLUB]
2314 Enabling slub_debug allows one to determine the
2315 culprit if slab objects become corrupted. Enabling
2316 slub_debug can create guard zones around objects and
2317 may poison objects when not in use. Also tracks the
2318 last alloc / free. For more information see
2319 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002320
2321 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002322 Determines the maximum allowed order for slabs.
2323 A high setting may cause OOMs due to memory
2324 fragmentation. For more information see
2325 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002326
2327 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002328 The minimum number of objects per slab. SLUB will
2329 increase the slab order up to slub_max_order to
2330 generate a sufficiently large slab able to contain
2331 the number of objects indicated. The higher the number
2332 of objects the smaller the overhead of tracking slabs
2333 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002334 For more information see Documentation/vm/slub.txt.
2335
2336 slub_min_order= [MM, SLUB]
2337 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002338 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002339 For more information see Documentation/vm/slub.txt.
2340
2341 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002342 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002343 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002344 allocs to different slabs. Debug options disable
2345 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002346 For more information see Documentation/vm/slub.txt.
2347
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 smart2= [HW]
2349 Format: <io1>[,<io2>[,...,<io8>]]
2350
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002351 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002352 attempt to substitute SMP alternatives once at boot.
2353
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002354 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2355 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2356 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2357 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2358 smsc-ircc2.ircc_irq= [HW] IRQ line
2359 smsc-ircc2.ircc_dma= [HW] DMA channel
2360 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2361 0: Toshiba Satellite 1800 (GP data pin select)
2362 1: Fast pin select (default)
2363 2: ATC IRMode
2364
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002365 softlockup_panic=
2366 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002367 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002368
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2370 See Documentation/sonypi.txt
2371
2372 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002373 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374
2375 spia_io_base= [HW,MTD]
2376 spia_fio_base=
2377 spia_pedr=
2378 spia_peddr=
2379
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002380 stacktrace [FTRACE]
2381 Enabled the stack tracer on boot up.
2382
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383 sti= [PARISC,HW]
2384 Format: <num>
2385 Set the STI (builtin display/keyboard on the HP-PARISC
2386 machines) console (graphic card) which should be used
2387 as the initial boot-console.
2388 See also comment in drivers/video/console/sticore.c.
2389
2390 sti_font= [HW]
2391 See comment in drivers/video/console/sticore.c.
2392
2393 stifb= [HW]
2394 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2395
Trond Myklebustcbf11072009-08-09 15:06:19 -04002396 sunrpc.min_resvport=
2397 sunrpc.max_resvport=
2398 [NFS,SUNRPC]
2399 SunRPC servers often require that client requests
2400 originate from a privileged port (i.e. a port in the
2401 range 0 < portnr < 1024).
2402 An administrator who wishes to reserve some of these
2403 ports for other uses may adjust the range that the
2404 kernel's sunrpc client considers to be privileged
2405 using these two parameters to set the minimum and
2406 maximum port values.
2407
Greg Banks42a7fc42007-03-06 01:42:23 -08002408 sunrpc.pool_mode=
2409 [NFS]
2410 Control how the NFS server code allocates CPUs to
2411 service thread pools. Depending on how many NICs
2412 you have and where their interrupts are bound, this
2413 option will affect which CPUs will do NFS serving.
2414 Note: this parameter cannot be changed while the
2415 NFS server is running.
2416
2417 auto the server chooses an appropriate mode
2418 automatically using heuristics
2419 global a single global pool contains all CPUs
2420 percpu one pool for each CPU
2421 pernode one pool for each NUMA node (equivalent
2422 to global on non-NUMA machines)
2423
Trond Myklebustcbf11072009-08-09 15:06:19 -04002424 sunrpc.tcp_slot_table_entries=
2425 sunrpc.udp_slot_table_entries=
2426 [NFS,SUNRPC]
2427 Sets the upper limit on the number of simultaneous
2428 RPC calls that can be sent from the client to a
2429 server. Increasing these values may allow you to
2430 improve throughput, but will also increase the
2431 amount of memory reserved for use by the client.
2432
Michal Hockoa42c3902010-11-24 12:57:08 -08002433 swapaccount[=0|1]
2434 [KNL] Enable accounting of swap in memory resource
2435 controller if no parameter or 1 is given or disable
2436 it if 0 is given (See Documentation/cgroups/memory.txt)
2437
Linus Torvalds1da177e2005-04-16 15:20:36 -07002438 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002439
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440 switches= [HW,M68k]
2441
Andi Kleene52eec12010-09-08 16:54:17 +02002442 sysfs.deprecated=0|1 [KNL]
2443 Enable/disable old style sysfs layout for old udev
2444 on older distributions. When this option is enabled
2445 very new udev will not work anymore. When this option
2446 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2447 in older udev will not work anymore.
2448 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2449 the kernel configuration.
2450
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002451 sysrq_always_enabled
2452 [KNL]
2453 Ignore sysrq setting - this boot parameter will
2454 neutralize any effect of /proc/sys/kernel/sysrq.
2455 Useful for debugging.
2456
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 tdfx= [HW,DRM]
2458
David Brownell77437fd2008-07-23 21:28:33 -07002459 test_suspend= [SUSPEND]
2460 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2461 standby suspend) as the system sleep state to briefly
2462 enter during system startup. The system is woken from
2463 this state using a wakeup-capable RTC alarm.
2464
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465 thash_entries= [KNL,NET]
2466 Set number of hash buckets for TCP connection
2467
Len Brownf8707ec2007-08-12 00:12:54 -04002468 thermal.act= [HW,ACPI]
2469 -1: disable all active trip points in all thermal zones
2470 <degrees C>: override all lowest active trip points
2471
Len Brownc52a7412007-08-14 15:49:32 -04002472 thermal.crt= [HW,ACPI]
2473 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002474 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002475
Len Brownf5487142007-08-12 00:12:44 -04002476 thermal.nocrt= [HW,ACPI]
2477 Set to disable actions on ACPI thermal zone
2478 critical and hot trip points.
2479
Len Brown72b33ef2007-08-12 00:12:17 -04002480 thermal.off= [HW,ACPI]
2481 1: disable ACPI thermal control
2482
Len Browna70cdc52007-08-12 00:12:35 -04002483 thermal.psv= [HW,ACPI]
2484 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002485 <degrees C>: override all passive trip points to this
2486 value
Len Browna70cdc52007-08-12 00:12:35 -04002487
Len Brown730ff342007-08-12 00:12:26 -04002488 thermal.tzp= [HW,ACPI]
2489 Specify global default ACPI thermal zone polling rate
2490 <deci-seconds>: poll all this frequency
2491 0: no polling (default)
2492
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002493 threadirqs [KNL]
2494 Force threading of all interrupt handlers except those
2495 marked explicitely IRQF_NO_THREAD.
2496
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002497 topology= [S390]
2498 Format: {off | on}
2499 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002500 topology information if the hardware supports this.
2501 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002502 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002503 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505 tp720= [HW,PS2]
2506
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002507 tpm_suspend_pcr=[HW,TPM]
2508 Format: integer pcr id
2509 Specify that at suspend time, the tpm driver
2510 should extend the specified pcr with zeros,
2511 as a workaround for some chips which fail to
2512 flush the last written pcr on TPM_SaveState.
2513 This will guarantee that all the other pcrs
2514 are saved.
2515
Li Zefan9d612be2009-06-24 17:33:15 +08002516 trace_buf_size=nn[KMG]
2517 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002518
Li Zefan020e5f82009-07-01 10:47:05 +08002519 trace_event=[event-list]
2520 [FTRACE] Set and start specified trace events in order
2521 to facilitate early boot debugging.
2522 See also Documentation/trace/events.txt
2523
john stultzd3b8f882009-08-17 16:40:47 -07002524 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002525 Format: <string>
2526 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002527 disables clocksource verification at runtime, as well
2528 as the stability checks done at bootup. Used to enable
2529 high-resolution timer mode on older hardware, and in
2530 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002531 [x86] noirqtime: Do not use TSC to do irq accounting.
2532 Used to run time disable IRQ_TIME_ACCOUNTING on any
2533 platforms where RDTSC is slow and this accounting
2534 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002535
Randy Dunlapa9913042005-10-23 12:57:11 -07002536 turbografx.map[2|3]= [HW,JOY]
2537 TurboGraFX parallel port interface
2538 Format:
2539 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002540 See also Documentation/input/joystick-parport.txt
2541
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002542 uhash_entries= [KNL,NET]
2543 Set number of hash buckets for UDP/UDP-Lite connections
2544
Alan Stern5f8364b2006-12-05 16:29:55 -05002545 uhci-hcd.ignore_oc=
2546 [USB] Ignore overcurrent events (default N).
2547 Some badly-designed motherboards generate lots of
2548 bogus events, for ports that aren't wired to
2549 anything. Set this parameter to avoid log spamming.
2550 Note that genuine overcurrent events won't be
2551 reported either.
2552
Simon Arlotte3a61b02008-07-19 23:32:54 +01002553 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002554 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01002555
Alan Sternb5e795f2007-02-20 15:00:53 -05002556 usbcore.autosuspend=
2557 [USB] The autosuspend time delay (in seconds) used
2558 for newly-detected USB devices (default 2). This
2559 is the time required before an idle device will be
2560 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002561 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002562
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002563 usbcore.usbfs_snoop=
2564 [USB] Set to log all usbfs traffic (default 0 = off).
2565
2566 usbcore.blinkenlights=
2567 [USB] Set to cycle leds on hubs (default 0 = off).
2568
2569 usbcore.old_scheme_first=
2570 [USB] Start with the old device initialization
2571 scheme (default 0 = off).
2572
2573 usbcore.use_both_schemes=
2574 [USB] Try the other device initialization scheme
2575 if the first one fails (default 1 = enabled).
2576
2577 usbcore.initial_descriptor_timeout=
2578 [USB] Specifies timeout for the initial 64-byte
2579 USB_REQ_GET_DESCRIPTOR request in milliseconds
2580 (default 5000 = 5.0 seconds).
2581
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 usbhid.mousepoll=
2583 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002584
Alan Sternd4f373e2008-11-10 14:07:45 -05002585 usb-storage.delay_use=
2586 [UMS] The delay in seconds before a new device is
2587 scanned for Logical Units (default 5).
2588
2589 usb-storage.quirks=
2590 [UMS] A list of quirks entries to supplement or
2591 override the built-in unusual_devs list. List
2592 entries are separated by commas. Each entry has
2593 the form VID:PID:Flags where VID and PID are Vendor
2594 and Product ID values (4-digit hex numbers) and
2595 Flags is a set of characters, each corresponding
2596 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002597 a = SANE_SENSE (collect more than 18 bytes
2598 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002599 b = BAD_SENSE (don't collect more than 18
2600 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002601 c = FIX_CAPACITY (decrease the reported
2602 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01002603 d = NO_READ_DISC_INFO (don't use
2604 READ_DISC_INFO command);
2605 e = NO_READ_CAPACITY_16 (don't use
2606 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05002607 h = CAPACITY_HEURISTICS (decrease the
2608 reported device capacity by one
2609 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002610 i = IGNORE_DEVICE (don't bind to this
2611 device);
2612 l = NOT_LOCKABLE (don't try to lock and
2613 unlock ejectable media);
2614 m = MAX_SECTORS_64 (don't transfer more
2615 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04002616 n = INITIAL_READ10 (force a retry of the
2617 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05002618 o = CAPACITY_OK (accept the capacity
2619 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002620 r = IGNORE_RESIDUE (the device reports
2621 bogus residue values);
2622 s = SINGLE_LUN (the device has only one
2623 Logical Unit);
2624 w = NO_WP_DETECT (don't test whether the
2625 medium is write-protected).
2626 Example: quirks=0419:aaf5:rl,0421:0433:rc
2627
Ian Campbell14315592010-02-17 10:38:10 +00002628 userpte=
2629 [X86] Flags controlling user PTE allocations.
2630
2631 nohigh = do not allocate PTE pages in
2632 HIGHMEM regardless of setting
2633 of CONFIG_HIGHPTE.
2634
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302635 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002636 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002637 vdso=1: enable VDSO (default)
2638 vdso=0: disable VDSO mapping
2639
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302640 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002641 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2642 vdso32=1: enable 32-bit VDSO (default)
2643 vdso32=0: disable 32-bit VDSO mapping
2644
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002645 vector= [IA-64,SMP]
2646 vector=percpu: enable percpu vector domain
2647
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648 video= [FB] Frame buffer configuration
2649 See Documentation/fb/modedb.txt.
2650
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002651 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002652 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002653 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654 Use vga=ask for menu.
2655 This is actually a boot loader parameter; the value is
2656 passed to the kernel using a special protocol.
2657
Randy Dunlapa9913042005-10-23 12:57:11 -07002658 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002659 size of <nn>. This can be used to increase the
2660 minimum size (128MB on x86). It can also be used to
2661 decrease the size and leave more room for directly
2662 mapped kernel RAM.
2663
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002664 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2665 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002667 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2668 Format: <command>
2669
2670 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2671 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002672
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002673 vt.cur_default= [VT] Default cursor shape.
2674 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2675 the parameters of the <Esc>[?A;B;Cc escape sequence;
2676 see VGA-softcursor.txt. Default: 2 = underline.
2677
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002678 vt.default_blu= [VT]
2679 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2680 Change the default blue palette of the console.
2681 This is a 16-member array composed of values
2682 ranging from 0-255.
2683
2684 vt.default_grn= [VT]
2685 Format: <green0>,<green1>,<green2>,...,<green15>
2686 Change the default green palette of the console.
2687 This is a 16-member array composed of values
2688 ranging from 0-255.
2689
2690 vt.default_red= [VT]
2691 Format: <red0>,<red1>,<red2>,...,<red15>
2692 Change the default red palette of the console.
2693 This is a 16-member array composed of values
2694 ranging from 0-255.
2695
2696 vt.default_utf8=
2697 [VT]
2698 Format=<0|1>
2699 Set system-wide default UTF-8 mode for all tty's.
2700 Default is 1, i.e. UTF-8 mode is enabled for all
2701 newly opened terminals.
2702
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002703 vt.global_cursor_default=
2704 [VT]
2705 Format=<-1|0|1>
2706 Set system-wide default for whether a cursor
2707 is shown on new VTs. Default is -1,
2708 i.e. cursors will be created by default unless
2709 overridden by individual drivers. 0 will hide
2710 cursors, 1 will display them.
2711
Randy Dunlap4724ba572010-05-03 11:42:52 -07002712 watchdog timers [HW,WDT] For information on watchdog timers,
2713 see Documentation/watchdog/watchdog-parameters.txt
2714 or other driver-specific files in the
2715 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002716
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002717 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2718 default x2apic cluster mode on platforms
2719 supporting x2apic.
2720
Jacob Panbb24c472009-09-02 07:37:17 -07002721 x86_mrst_timer= [X86-32,APBT]
2722 Choose timer option for x86 Moorestown MID platform.
2723 Two valid options are apbt timer only and lapic timer
2724 plus one apbt timer for broadcast timer.
2725 x86_mrst_timer=apbt_only | lapic_and_apbt
2726
Linus Torvalds1da177e2005-04-16 15:20:36 -07002727 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2728 xd_geo= See header of drivers/block/xd.c.
2729
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002730 xen_emul_unplug= [HW,X86,XEN]
2731 Unplug Xen emulated devices
2732 Format: [unplug0,][unplug1]
2733 ide-disks -- unplug primary master IDE devices
2734 aux-ide-disks -- unplug non-primary-master IDE devices
2735 nics -- unplug network devices
2736 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002737 unnecessary -- unplugging emulated devices is
2738 unnecessary even if the host did not respond to
2739 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002740 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002741
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002743 Format:
2744 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002745
Randy Dunlapa9913042005-10-23 12:57:11 -07002746______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747
2748TODO:
2749
Linus Torvalds1da177e2005-04-16 15:20:36 -07002750 Add more DRM drivers.