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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,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800248 old_ordering, s4_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
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200302 amd_iommu= [HW,X86-84]
303 Pass parameters to the AMD IOMMU driver in the system.
304 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900305 fullflush - enable flushing of IO/TLB entries when
306 they are unmapped. Otherwise they are
307 flushed before they will be reused, which
308 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200309 off - do not initialize any AMD IOMMU found in
310 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900311
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 amijoy.map= [HW,JOY] Amiga joystick support
313 Map of devices attached to JOY0DAT and JOY1DAT
314 Format: <a>,<b>
315 See also Documentation/kernel/input/joystick.txt
316
317 analog.map= [HW,JOY] Analog joystick and gamepad support
318 Specifies type or capabilities of an analog joystick
319 connected to one of 16 gameports
320 Format: <type1>,<type2>,..<type16>
321
Randy Dunlapa9913042005-10-23 12:57:11 -0700322 apc= [HW,SPARC]
323 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 Format: noidle
325 Disable APC CPU standby support. SPARCstation-Fox does
326 not play well with APC CPU idle - disable it if you have
327 APC and your system crashes randomly.
328
Randy Dunlapca1eda22009-05-06 16:02:58 -0700329 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700330 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 Format: { quiet (default) | verbose | debug }
332 Change the amount of debugging information output
333 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700334
Brian Haleyb0f83b22010-02-04 13:36:50 -0800335 autoconf= [IPV6]
336 See Documentation/networking/ipv6.txt.
337
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400338 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
339 Limit apic dumping. The parameter defines the maximal
340 number of local apics being dumped. Also it is possible
341 to set it to "all" by meaning -- no limit here.
342 Format: { 1 (default) | 2 | ... | all }.
343 The parameter valid if only apic=debug or
344 apic=verbose is specified.
345 Example: apic=debug show_lapic=all
346
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700348 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
351 Format: <io>,<irq>,<nodeID>
352
353 ataflop= [HW,M68k]
354
355 atarimouse= [HW,MOUSE] Atari Mouse
356
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
358 EzKey and similar keyboards
359
360 atkbd.reset= [HW] Reset keyboard during initialization
361
Randy Dunlapa9913042005-10-23 12:57:11 -0700362 atkbd.set= [HW] Select keyboard code set
363 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364
365 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
366 keyboards
367
368 atkbd.softraw= [HW] Choose between synthetic and real raw mode
369 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700370
371 atkbd.softrepeat= [HW]
372 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373
374 autotest [IA64]
375
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 baycom_epp= [HW,AX25]
377 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 Format: <io>,<mode>
381 See header of drivers/net/hamradio/baycom_par.c.
382
Randy Dunlapa9913042005-10-23 12:57:11 -0700383 baycom_ser_fdx= [HW,AX25]
384 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 Format: <io>,<irq>,<mode>[,<baud>]
386 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387
Randy Dunlapa9913042005-10-23 12:57:11 -0700388 baycom_ser_hdx= [HW,AX25]
389 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 Format: <io>,<irq>,<mode>
391 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700393 boot_delay= Milliseconds to delay each printk during boot.
394 Values larger than 10 seconds (10000) are changed to
395 no delay (0).
396 Format: integer
397
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700398 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700401 bttv.radio= Most important insmod options are available as
402 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
404 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
405
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000406 bulk_remove=off [PPC] This parameter disables the use of the pSeries
407 firmware feature for flushing multiple hpte entries
408 at a time.
409
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 c101= [NET] Moxa C101 synchronous serial card
411
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700412 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 Sometimes CPU hardware bugs make them report the cache
414 size incorrectly. The kernel will attempt work arounds
415 to fix known problems, but for some CPUs it is not
416 possible to determine what the correct size should be.
417 This option provides an override for these situations.
418
James Morris20510f22007-10-16 23:31:32 -0700419 capability.disable=
420 [SECURITY] Disable capabilities. This would normally
421 be used only if an alternative security model is to be
422 configured. Potentially dangerous and should only be
423 used if you are entirely sure of the consequences.
424
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100425 ccw_timeout_log [S390]
426 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427
Paul Menage8bab8dd2008-04-04 14:29:57 -0700428 cgroup_disable= [KNL] Disable a particular controller
429 Format: {name of the controller(s) to disable}
430 {Currently supported controllers - "memory"}
431
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 checkreqprot [SELINUX] Set initial checkreqprot flag value.
433 Format: { "0" | "1" }
434 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700435 0 -- check protection applied by kernel (includes
436 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 1 -- check protection requested by application.
438 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700439 Value can be changed at runtime via
440 /selinux/checkreqprot.
441
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100442 cio_ignore= [S390]
443 See Documentation/s390/CommonIO for details.
444
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700445 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700446 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200447 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700448 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200449 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 Format: { pit | tsc | cyclone | pmtmr }
451
John Stultz592913e2010-07-13 17:56:20 -0700452 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700453 Format: <string>
454 Override the default clocksource and use the clocksource
455 with the name specified.
456 Some clocksource names to choose from, depending on
457 the platform:
458 [all] jiffies (this is the base, fallback clocksource)
459 [ACPI] acpi_pm
460 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
461 pxa_timer,timer3,32k_counter,timer0_1
462 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700463 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700464 scx200_hrt on Geode; cyclone on IBM x440
465 [MIPS] MIPS
466 [PARISC] cr16
467 [S390] tod
468 [SH] SuperH
469 [SPARC64] tick
470 [X86-64] hpet,tsc
471
Andi Kleenac72e782008-01-30 13:33:21 +0100472 clearcpuid=BITNUM [X86]
473 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800474 arch/x86/include/asm/cpufeature.h for the valid bit
475 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100476 stable over kernel options, but the vendor specific
477 ones should be.
478 Also note that user programs calling CPUID directly
479 or using the feature without checking anything
480 will still see it. This just prevents it from
481 being used by the kernel or shown in /proc/cpuinfo.
482 Also note the kernel might malfunction if you disable
483 some critical bits.
484
Robert Jennings14f966e2009-04-15 05:55:32 +0000485 cmo_free_hint= [PPC] Format: { yes | no }
486 Specify whether pages are marked as being inactive
487 when they are freed. This is used in CMO environments
488 to determine OS memory pressure for page stealing by
489 a hypervisor.
490 Default: yes
491
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530492 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100493 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100494 Range: 0 - 8192
495 Default: 64
496
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700498 Format:
499 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
501 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
502 Format: <io>[,<irq>]
503
Randy Dunlapa9913042005-10-23 12:57:11 -0700504 com90xx= [HW,NET]
505 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 Format: <io>[,<irq>[,<memstart>]]
507
508 condev= [HW,S390] console device
509 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700510
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 console= [KNL] Output console device and options.
512
513 tty<n> Use the virtual console device <n>.
514
515 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800516 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800518 the form "bbbbpnf", where "bbbb" is the baud rate,
519 "p" is parity ("n", "o", or "e"), "n" is number of
520 bits, and "f" is flow control ("r" for RTS or
521 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800523 See Documentation/serial-console.txt for more
524 information. See
525 Documentation/networking/netconsole.txt for an
526 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700528 uart[8250],io,<addr>[,options]
529 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 Start an early, polled-mode console on the 8250/16550
531 UART at the specified I/O port or MMIO address,
532 switching to the matching ttyS device later. The
533 options are the same as for ttyS, above.
534
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700535 If the device connected to the port is not a TTY but a braille
536 device, prepend "brl," before the device type, for instance
537 console=brl,ttyS0
538 For now, only VisioBraille is supported.
539
Daniel Mackf324edc2009-06-16 15:33:52 -0700540 consoleblank= [KNL] The console blank (screen saver) timeout in
541 seconds. Defaults to 10*60 = 10mins. A value of 0
542 disables the blank timer.
543
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800544 coredump_filter=
545 [KNL] Change the default value for
546 /proc/<pid>/coredump_filter.
547 See also Documentation/filesystems/proc.txt.
548
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700550 Format:
551 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800553 crashkernel=size[KMG][@offset[KMG]]
554 [KNL] Using kexec, Linux can switch to a 'crash kernel'
555 upon panic. This parameter reserves the physical
556 memory region [offset, offset + size] for that kernel
557 image. If '@offset' is omitted, then a suitable offset
558 is selected automatically. Check
559 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700560
Bernhard Wallefb391592007-10-18 23:41:02 -0700561 crashkernel=range1:size1[,range2:size2,...][@offset]
562 [KNL] Same as above, but depends on the memory
563 in the running system. The syntax of range is
564 start-[end] where start and end are both
565 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800566 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700567
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 cs89x0_dma= [HW,NET]
569 Format: <dma>
570
571 cs89x0_media= [HW,NET]
572 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700573
Randy Dunlapa9913042005-10-23 12:57:11 -0700574 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 See header of drivers/s390/block/dasd_devmap.c.
576
577 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
578 (one device per port)
579 Format: <port#>,<type>
580 See also Documentation/input/joystick-parport.txt
581
Thomas Renningera648ec02010-08-06 16:11:02 +0200582 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
583 time. See Documentation/dynamic-debug-howto.txt for
584 details.
585
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 debug [KNL] Enable kernel debugging (events log level).
587
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700588 debug_locks_verbose=
589 [KNL] verbose self-tests
590 Format=<0|1>
591 Print debugging info while doing the locking API
592 self-tests.
593 We default to 0 (no extra messages), setting it to
594 1 will print _a lot_ more information - normally
595 only useful to kernel developers.
596
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700597 debug_objects [KNL] Enable object debugging
598
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500599 no_debug_objects
600 [KNL] Disable object debugging
601
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200602 debugpat [X86] Enable PAT debugging
603
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200604 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 Format: <area>[,<node>]
606 See also Documentation/networking/decnet.txt.
607
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700608 default_hugepagesz=
609 [same as hugepagesz=] The size of the default
610 HugeTLB page size. This is the size represented by
611 the legacy /proc/ hugepages APIs, used for SHM, and
612 default size when mounting hugetlbfs filesystems.
613 Defaults to the default architecture's huge page size
614 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700615
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 dhash_entries= [KNL]
617 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700618
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 digi= [HW,SERIAL]
620 IO parameters + enable/disable command.
621
622 digiepca= [HW,SERIAL]
623 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000624 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625
Brian Haleyb0f83b22010-02-04 13:36:50 -0800626 disable= [IPV6]
627 See Documentation/networking/ipv6.txt.
628
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000629 disable_ddw [PPC/PSERIES]
630 Disable Dynamic DMA Window support. Use this if
631 to workaround buggy firmware.
632
Brian Haleyb0f83b22010-02-04 13:36:50 -0800633 disable_ipv6= [IPV6]
634 See Documentation/networking/ipv6.txt.
635
Yinghai Lu95ffa242008-04-29 03:52:33 -0700636 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700637 The kernel tries to adjust MTRR layout from continuous
638 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700639 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700640
Yinghai Lu093af8d2008-01-30 13:33:32 +0100641 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100642 By default the kernel will trim any uncacheable
643 memory out of your available memory pool based on
644 MTRR settings. This parameter disables that behavior,
645 possibly causing your machine to run very slowly.
646
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530647 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700648 Disable PIN 1 of APIC timer
649 Can be useful to work around chipset bugs.
650
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700651 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
652 this option disables the debugging code at boot.
653
654 dma_debug_entries=<number>
655 This option allows to tune the number of preallocated
656 entries for DMA-API debugging code. One entry is
657 required per DMA-API allocation. Use this if the
658 DMA-API debugging code disables itself because the
659 architectural default is too low.
660
Joerg Roedel1745de52009-05-22 21:49:51 +0200661 dma_debug_driver=<driver_name>
662 With this option the DMA-API debugging driver
663 filter feature can be enabled at boot time. Just
664 pass the driver to filter for as the parameter.
665 The filter can be disabled or changed to another
666 driver later using sysfs.
667
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 dscc4.setup= [NET]
669
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700670 earlycon= [KNL] Output early console device and options.
671 uart[8250],io,<addr>[,options]
672 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700673 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700674 Start an early, polled-mode console on the 8250/16550
675 UART at the specified I/O port or MMIO address.
Samium Gromoff1917ac72010-07-20 15:26:51 -0700676 MMIO inter-register address stride is either 8bit (mmio)
677 or 32bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700678 The options are the same as for ttyS, above.
679
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530680 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 earlyprintk=vga
682 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500683 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500684 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685
Randy Dunlapa9913042005-10-23 12:57:11 -0700686 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 takes over.
688
Yinghai Lu5c059172008-07-24 17:29:40 -0700689 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690
691 Currently only ttyS0 and ttyS1 are supported.
692
693 Interaction with the standard serial driver is not
694 very good.
695
696 The VGA output is eventually overwritten by the real
697 console.
698
Jason Wessel97311912010-05-20 21:04:30 -0500699 ekgdboc= [X86,KGDB] Allow early kernel console debugging
700 ekgdboc=kbd
701
702 This is desgined to be used in conjunction with
703 the boot argument: earlyprintk=vga
704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700706 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 eisa_irq_edge= [PARISC,HW]
709 See header of drivers/parisc/eisa.c.
710
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700711 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700713 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714
715 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100716 Format: {"cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700717 See Documentation/block/as-iosched.txt and
718 Documentation/block/deadline-iosched.txt for details.
719
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530720 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700721 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800722 image elf header. Generally kexec loader will
723 pass this option to capture kernel.
724 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700726 enable_mtrr_cleanup [X86]
727 The kernel tries to adjust MTRR layout from continuous
728 to discrete, to make X server driver able to add WB
729 entry later. This parameter enables that.
730
Randy Dunlapca1eda22009-05-06 16:02:58 -0700731 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700732 Enable PIN 1 of APIC timer
733 Can be useful to work around chipset bugs
734 (in particular on some ATI chipsets).
735 The kernel tries to set a reasonable default.
736
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 enforcing [SELINUX] Set initial enforcing status.
738 Format: {"0" | "1"}
739 See security/selinux/Kconfig help text.
740 0 -- permissive (log only, no denials).
741 1 -- enforcing (deny and log).
742 Default value is 0.
743 Value can be changed at runtime via /selinux/enforce.
744
Huang Yinga08f82d2010-05-18 14:35:21 +0800745 erst_disable [ACPI]
746 Disable Error Record Serialization Table (ERST)
747 support.
748
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 ether= [HW,NET] Ethernet cards parameters
750 This option is obsoleted by the "netdev=" option, which
751 has equivalent usage. See its documentation for details.
752
Akinobu Mitade1ba092006-12-08 02:39:42 -0800753 failslab=
754 fail_page_alloc=
755 fail_make_request=[KNL]
756 General fault injection mechanism.
757 Format: <interval>,<probability>,<space>,<times>
758 See also /Documentation/fault-injection/.
759
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000761 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Alex Chiangf13ae302008-05-08 14:03:23 -0600763 force_pal_cache_flush
764 [IA-64] Avoid check_sal_cache_flush which may hang on
765 buggy SAL_CACHE_FLUSH implementations. Using this
766 parameter will force ia64_sal_cache_flush to call
767 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
768
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100769 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400770 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100771 as early as possible in order to facilitate early
772 boot debugging.
773
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200774 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400775 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200776 If no parameter is passed, ftrace will dump
777 buffers of all CPUs, but if you pass orig_cpu, it will
778 dump only the buffer of the CPU that triggered the
779 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400780
781 ftrace_filter=[function-list]
782 [FTRACE] Limit the functions traced by the function
783 tracer at boot up. function-list is a comma separated
784 list of functions. This list can be changed at run
785 time by the set_ftrace_filter file in the debugfs
786 tracing directory.
787
788 ftrace_notrace=[function-list]
789 [FTRACE] Do not trace the functions specified in
790 function-list. This list can be changed at run time
791 by the set_ftrace_notrace file in the debugfs
792 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100793
Stefan Assmann369bc182009-10-12 22:17:21 +0200794 ftrace_graph_filter=[function-list]
795 [FTRACE] Limit the top level callers functions traced
796 by the function graph tracer at boot up.
797 function-list is a comma separated list of functions
798 that can be changed at run time by the
799 set_graph_function file in the debugfs tracing directory.
800
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 gamecon.map[2|3]=
802 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
803 support via parallel port (up to 5 devices per port)
804 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
805 See also Documentation/input/joystick-parport.txt
806
807 gamma= [HW,DRM]
808
Yinghai Luaaf23042008-01-30 13:33:09 +0100809 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
810 Format: off | on
811 default: on
812
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700813 gcov_persist= [GCOV] When non-zero (default), profiling data for
814 kernel modules is saved and remains accessible via
815 debugfs, even when the module is unloaded/reloaded.
816 When zero, profiling data is discarded and associated
817 debugfs files are removed at module unload time.
818
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 gpt [EFI] Forces disk with valid GPT signature but
820 invalid Protective MBR to be treated as GPT.
821
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 hashdist= [KNL,NUMA] Large hashes allocated during boot
823 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700824 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700825 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
827 hcl= [IA-64] SGI's Hardware Graph compatibility layer
828
829 hd= [EIDE] (E)IDE hard drive subsystem geometry
830 Format: <cyl>,<head>,<sect>
831
Huang Yingea8c0712010-05-18 14:35:15 +0800832 hest_disable [ACPI]
833 Disable Hardware Error Source Table (HEST) support;
834 corresponding firmware-first mode error processing
835 logic will be disabled.
836
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
838 size of <nn>. This works even on boxes that have no
839 highmem otherwise. This also works to reduce highmem
840 size on bigger boxes.
841
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800842 highres= [KNL] Enable/disable high resolution timer mode.
843 Valid parameters: "on", "off"
844 Default: "on"
845
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 hisax= [HW,ISDN]
847 See Documentation/isdn/README.HiSax.
848
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700849 hlt [BUGS=ARM,SH]
850
851 hpet= [X86-32,HPET] option to control HPET usage
852 Format: { enable (default) | disable | force |
853 verbose }
854 disable: disable HPET and use PIT instead
855 force: allow force enabled of undocumented chips (ICH4,
856 VIA, nVidia)
857 verbose: show contents of HPET registers during setup
858
Andi Kleenb4718e62008-07-23 21:27:51 -0700859 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
860 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700861 On x86-64 and powerpc, this option can be specified
862 multiple times interleaved with hugepages= to reserve
863 huge pages of different sizes. Valid pages sizes on
864 x86-64 are 2M (when the CPU supports "pse") and 1G
865 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700866 Note that 1GB pages can only be allocated at boot time
867 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900868
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100869 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
870 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100871 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
872 If specified, z/VM IUCV HVC accepts connections
873 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100874
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700875 keep_bootcon [KNL]
876 Do not unregister boot console at start. This is only
877 useful for debugging when something happens in the window
878 between unregistering the boot console and initializing
879 the real console.
880
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700881 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700882 or register an additional I2C bus that is not
883 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700884 Format:
885 <bus_id>,<clkrate>
886
Jiri Kosina36d95732008-10-06 02:51:09 -0400887 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200889 i8042.dumbkbd [HW] Pretend that controller can only read data from
890 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 (Don't attempt to blink the leds)
892 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500893 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400894 i8042.noloop [HW] Disable the AUX Loopback command while probing
895 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 i8042.nomux [HW] Don't check presence of an active multiplexing
897 controller
898 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
899 controllers
Jiri Kosinaf8313ef2011-01-08 01:37:26 -0800900 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 i8042.reset [HW] Reset the controller during init and cleanup
902 i8042.unlock [HW] Unlock (ignore) the keylock
903
904 i810= [HW,DRM]
905
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700906 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
907 indicates that the driver is running on unsupported
908 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
910 does not match list of supported models.
911 i8k.power_status
912 [HW] Report power status in /proc/i8k
913 (disabled by default)
914 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
915 capability is set.
916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 icn= [HW,ISDN]
918 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
919
David Fries0af80c02009-02-25 20:28:21 +0100920 ide-core.nodma= [HW] (E)IDE subsystem
921 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200922 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
923 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100924 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700926 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
927 Claim all unknown PCI IDE storage controllers.
928
Andi Kleenf039b752007-05-02 19:27:12 +0200929 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800930 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
931 Poll forces a polling idle loop that can slightly
932 improve the performance of waking up a idle CPU, but
933 will use a lot of power and make the system run hot.
934 Not recommended.
935 idle=mwait: On systems which support MONITOR/MWAIT but
936 the kernel chose to not use it because it doesn't save
937 as much power as a normal idle loop, use the
938 MONITOR/MWAIT idle loop anyways. Performance should be
939 the same as idle=poll.
940 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800941 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800942 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700943
Ingo Molnar792908222006-12-06 20:40:51 -0800944 ignore_loglevel [KNL]
945 Ignore loglevel setting - this will print /all/
946 kernel messages to the console. Useful for debugging.
947
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 ihash_entries= [KNL]
949 Set number of hash buckets for inode cache.
950
Mimi Zohar3323eec92009-02-04 09:06:58 -0500951 ima_audit= [IMA]
952 Format: { "0" | "1" }
953 0 -- integrity auditing messages. (Default)
954 1 -- enable informational integrity auditing messages.
955
956 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700957 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500958 default: "sha1"
959
Eric Paris5789ba32009-05-21 15:47:06 -0400960 ima_tcb [IMA]
961 Load a policy which meets the needs of the Trusted
962 Computing Base. This means IMA will measure all
963 programs exec'd, files mmap'd for exec, and all files
964 opened for read by uid=0.
965
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 init= [KNL]
967 Format: <full_path>
968 Run specified binary instead of /sbin/init as init
969 process.
970
971 initcall_debug [KNL] Trace initcalls as they are executed. Useful
972 for working out where the kernel is dying during
973 startup.
974
975 initrd= [BOOT] Specify the location of the initial ramdisk
976
977 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
978 Format: <irq>
979
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700980 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800981 on
982 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700983 off
984 Disable intel iommu driver.
985 igfx_off [Default Off]
986 By default, gfx is mapped as normal device. If a gfx
987 device has a dedicated DMAR unit, the DMAR unit is
988 bypassed by not enabling DMAR with this option. In
989 this case, gfx device will use physical address for
990 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700991 forcedac [x86_64]
992 With this option iommu will not optimize to look
993 for io virtual address below 32 bit forcing dual
994 address cycle on pci bus for cards supporting greater
995 than 32 bit addressing. The default is to look
996 for translation below 32 bit and if not available
997 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800998 strict [Default Off]
999 With this option on every unmap_single operation will
1000 result in a hardware IOTLB flush operation as opposed
1001 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001002
Chris Wrightd1423d52010-07-20 11:06:49 -07001003 intremap= [X86-64, Intel-IOMMU]
1004 Format: { on (default) | off | nosid }
1005 on enable Interrupt Remapping (default)
1006 off disable Interrupt Remapping
1007 nosid disable Source ID checking
1008
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001009 inttest= [IA64]
1010
1011 iomem= Disable strict checking of access to MMIO memory
1012 strict regions from userspace.
1013 relaxed
1014
1015 iommu= [x86]
1016 off
1017 force
1018 noforce
1019 biomerge
1020 panic
1021 nopanic
1022 merge
1023 nomerge
1024 forcesac
1025 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001026 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001027
1028 io7= [HW] IO7 for Marvel based alpha systems
1029 See comment before marvel_specify_io7 in
1030 arch/alpha/kernel/core_marvel.c.
1031
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301032 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001033 0x80
1034 Standard port 0x80 based delay
1035 0xed
1036 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001037 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001038 Simple two microseconds delay
1039 none
1040 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001041
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001043 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001046 See comment before ip2_setup() in
1047 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
Alan Cox200803d2005-06-28 20:45:18 -07001049 irqfixup [HW]
1050 When an interrupt is not handled search all handlers
1051 for it. Intended to get systems with badly broken
1052 firmware running.
1053
1054 irqpoll [HW]
1055 When an interrupt is not handled search all handlers
1056 for it. Also check all handlers each timer
1057 interrupt. Intended to get systems with badly broken
1058 firmware running.
1059
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001061 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
1063 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001064 Format:
1065 <cpu number>,...,<cpu number>
1066 or
Li Zefanb225d442008-11-06 12:53:39 -08001067 <cpu number>-<cpu number>
1068 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001069 or a mixture
1070 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001071
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 This option can be used to specify one or more CPUs
1073 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001074 algorithms. You can move a process onto or off an
1075 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 <cpu number> begins at 0 and the maximum value is
1077 "number of CPUs in system - 1".
1078
1079 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001080 alternative -- manually setting the CPU mask of all
1081 tasks in the system -- can cause problems and
1082 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
Randy Dunlapa9913042005-10-23 12:57:11 -07001084 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
1086 js= [HW,JOY] Analog joystick
1087 See Documentation/input/joystick.txt.
1088
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001089 keepinitrd [HW,ARM]
1090
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301091 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001092 specifies the amount of memory usable by the kernel
1093 for non-movable allocations. The requested amount is
1094 spread evenly throughout all nodes in the system. The
1095 remaining memory in each node is used for Movable
1096 pages. In the event, a node is too small to have both
1097 kernelcore and Movable pages, kernelcore pages will
1098 take priority and other nodes will have a larger number
1099 of kernelcore pages. The Movable zone is used for the
1100 allocation of pages that may be reclaimed or moved
1101 by the page migration subsystem. This means that
1102 HugeTLB pages may not be allocated from this zone.
1103 Note that allocations like PTEs-from-HighMem still
1104 use the HighMem zone if it exists, and the Normal
1105 zone if it does not.
1106
Jason Wessel4fe1da42010-05-20 21:04:31 -05001107 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1108 Format: <Controller#>[,poll interval]
1109 The controller # is the number of the ehci usb debug
1110 port as it is probed via PCI. The poll interval is
1111 optional and is the number seconds in between
1112 each poll cycle to the debug port in case you need
1113 the functionality for interrupting the kernel with
1114 gdb or control-c on the dbgp connection. When
1115 not using this parameter you use sysrq-g to break into
1116 the kernel debugger.
1117
Jason Wessel84c08fd2010-05-20 21:04:24 -05001118 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001119 Requires a tty driver that supports console polling,
1120 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001121 Serial only format: <serial_device>[,baud]
1122 keyboard only format: kbd
1123 keyboard and serial format: kbd,<serial_device>[,baud]
1124 Optional Kernel mode setting:
1125 kms, kbd format: kms,kbd
1126 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001127
Jason Wessel84c08fd2010-05-20 21:04:24 -05001128 kgdbwait [KGDB] Stop kernel execution and enter the
1129 kernel debugger at the earliest opportunity.
1130
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001131 kmac= [MIPS] korina ethernet MAC address.
1132 Configure the RouterBoard 532 series on-chip
1133 Ethernet adapter MAC address.
1134
Catalin Marinas04f70332009-06-11 13:22:39 +01001135 kmemleak= [KNL] Boot-time kmemleak enable/disable
1136 Valid arguments: on, off
1137 Default: on
1138
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301139 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001140 in oops dumps.
1141
Andre Przywarafef07aa2009-07-10 14:20:35 +02001142 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1143 Default is 0 (don't ignore, but inject #GP)
1144
1145 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1146 Default is 1 (enabled)
1147
Xiao Guangronga182d872010-09-20 22:17:48 +08001148 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1149 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001150 Default is 0 (off)
1151
Andre Przywarafef07aa2009-07-10 14:20:35 +02001152 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001153 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001154
1155 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1156 for all guests.
1157 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1158
1159 kvm-intel.bypass_guest_pf=
1160 [KVM,Intel] Disables bypassing of guest page faults
1161 on Intel chips. Default is 1 (enabled)
1162
1163 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1164 (virtualized MMU) support on capable Intel chips.
1165 Default is 1 (enabled)
1166
1167 kvm-intel.emulate_invalid_guest_state=
1168 [KVM,Intel] Enable emulation of invalid guest states
1169 Default is 0 (disabled)
1170
1171 kvm-intel.flexpriority=
1172 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1173 Default is 1 (enabled)
1174
1175 kvm-intel.unrestricted_guest=
1176 [KVM,Intel] Disable unrestricted guest feature
1177 (virtualized real and unpaged mode) on capable
1178 Intel chips. Default is 1 (enabled)
1179
1180 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1181 feature (tagged TLBs) on capable Intel chips.
1182 Default is 1 (enabled)
1183
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 l2cr= [PPC]
1185
Robert Brosea78bfbf2008-03-29 07:20:23 +11001186 l3cr= [PPC]
1187
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001188 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001189 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301191 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001192 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001193
FD Camifcb71f62008-01-06 19:08:56 +01001194 libata.dma= [LIBATA] DMA control
1195 libata.dma=0 Disable all PATA and SATA DMA
1196 libata.dma=1 PATA and SATA Disk DMA only
1197 libata.dma=2 ATAPI (CDROM) DMA only
1198 libata.dma=4 Compact Flash DMA only
1199 Combinations also work, so libata.dma=3 enables DMA
1200 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001201
1202 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1203 libata.ignore_hpa=0 keep BIOS limits (default)
1204 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001205
Dave Jones78e70c22007-09-27 11:50:13 -04001206 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1207 when set.
1208 Format: <int>
1209
Tejun Heo33267322008-02-13 09:15:09 +09001210 libata.force= [LIBATA] Force configurations. The format is comma
1211 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001212 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001213 matching port, link or device. Basically, it matches
1214 the ATA ID string printed on console by libata. If
1215 the whole ID part is omitted, the last PORT and DEVICE
1216 values are used. If ID hasn't been specified yet, the
1217 configuration applies to all ports, links and devices.
1218
1219 If only DEVICE is omitted, the parameter applies to
1220 the port and all links and devices behind it. DEVICE
1221 number of 0 either selects the first device or the
1222 first fan-out link behind PMP device. It does not
1223 select the host link. DEVICE number of 15 selects the
1224 host link and device attached to it.
1225
1226 The VAL specifies the configuration to force. As long
1227 as there's no ambiguity shortcut notation is allowed.
1228 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1229 The following configurations can be forced.
1230
1231 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1232 Any ID with matching PORT is used.
1233
1234 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1235
1236 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1237 udma[/][16,25,33,44,66,100,133] notation is also
1238 allowed.
1239
1240 * [no]ncq: Turn on or off NCQ.
1241
Tejun Heo05944bd2008-08-13 20:19:09 +09001242 * nohrst, nosrst, norst: suppress hard, soft
1243 and both resets.
1244
Tejun Heo43c9c592010-05-23 12:59:11 +02001245 * dump_id: dump IDENTIFY data.
1246
Tejun Heo33267322008-02-13 09:15:09 +09001247 If there are multiple matching configurations changing
1248 the same attribute, the last one is used.
1249
Yinghai Lu95f72d12010-07-12 14:36:09 +10001250 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001251
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001253 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001255 lockd.nlm_grace_period=P [NFS] Assign grace period.
1256 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001258 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1259 Format: <integer>
1260
1261 lockd.nlm_timeout=T [NFS] Assign timeout value.
1262 Format: <integer>
1263
1264 lockd.nlm_udpport=M [NFS] Assign UDP port.
1265 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266
1267 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1268 Format: <irq>
1269
1270 loglevel= All Kernel Messages with a loglevel smaller than the
1271 console loglevel will be printed to the console. It can
1272 also be changed with klogd or other programs. The
1273 loglevels are defined as follows:
1274
1275 0 (KERN_EMERG) system is unusable
1276 1 (KERN_ALERT) action must be taken immediately
1277 2 (KERN_CRIT) critical conditions
1278 3 (KERN_ERR) error conditions
1279 4 (KERN_WARNING) warning conditions
1280 5 (KERN_NOTICE) normal but significant condition
1281 6 (KERN_INFO) informational
1282 7 (KERN_DEBUG) debug-level messages
1283
Randy Dunlapc756d082011-02-20 20:08:35 -08001284 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1285 in bytes. n must be a power of two. The default
1286 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287
Randy Dunlapaccaa242007-10-16 01:29:37 -07001288 logo.nologo [FB] Disables display of the built-in Linux logo.
1289 This may be used to provide more screen space for
1290 kernel log messages and is useful when debugging
1291 kernel boot problems.
1292
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293 lp=0 [LP] Specify parallel ports to use, e.g,
1294 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1295 lp=reset first parallel port). 'lp=0' disables the
1296 lp=auto printer driver. 'lp=reset' (which can be
1297 specified in addition to the ports) causes
1298 attached printers to be reset. Using
1299 lp=port1,port2,... specifies the parallel ports
1300 to associate lp devices with, starting with
1301 lp0. A port specification may be 'none' to skip
1302 that lp device, or a parport name such as
1303 'parport0'. Specifying 'lp=auto' instead of a
1304 port specification list means that device IDs
1305 from each port should be examined, to see if
1306 an IEEE 1284-compliant printer is attached; if
1307 so, the driver will manage that printer.
1308 See also header of drivers/char/lp.c.
1309
1310 lpj=n [KNL]
1311 Sets loops_per_jiffy to given constant, thus avoiding
1312 time-consuming boot-time autodetection (up to 250 ms per
1313 CPU). 0 enables autodetection (default). To determine
1314 the correct value for your kernel, boot with normal
1315 autodetection and see what value is printed. Note that
1316 on SMP systems the preset will be applied to all CPUs,
1317 which is likely to cause problems if your CPUs need
1318 significantly divergent settings. An incorrect value
1319 will cause delays in the kernel to be wrong, leading to
1320 unpredictable I/O errors and other breakage. Although
1321 unlikely, in the extreme case this might damage your
1322 hardware.
1323
1324 ltpc= [NET]
1325 Format: <io>,<irq>,<dma>
1326
Randy Dunlapa9913042005-10-23 12:57:11 -07001327 machvec= [IA64] Force the use of a particular machine-vector
1328 (machvec) in a generic kernel.
1329 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Wu Zhangjin3209e702009-07-02 23:27:12 +08001331 machtype= [Loongson] Share the same kernel image file between different
1332 yeeloong laptop.
1333 Example: machtype=lemote-yeeloong-2f-7inch
1334
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001335 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1336 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337
1338 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001339 should make use of. maxcpus=n : n >= 0 limits the
1340 kernel to using 'n' processors. n=0 is a special case,
1341 it is equivalent to "nosmp", which also disables
1342 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001344 max_loop= [LOOP] Maximum number of loopback devices that can
1345 be mounted
1346 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001347
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 mcatest= [IA-64]
1349
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001350 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351
Uwe Hermann71cced62008-10-20 09:32:21 -07001352 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001353
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 md= [HW] RAID subsystems devices and level
1355 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 mdacon= [MDA]
1358 Format: <first>,<last>
1359 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001360
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1362 Amount of memory to be used when the kernel is not able
1363 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001364 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 address space collisions. Without memmap= PCI devices
1366 could be placed at addresses belonging to unused RAM.
1367
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001368 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 memory.
1370
Paul Mundt6902aa82008-09-21 17:14:42 +09001371 memchunk=nn[KMG]
1372 [KNL,SH] Allow user to override the default size for
1373 per-device physically contiguous DMA buffers.
1374
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301375 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 E820 memory map, as specified by the user.
1377 Such memmap=exactmap lines can be constructed based on
1378 BIOS output or other requirements. See the memmap=nn@ss
1379 option description.
1380
1381 memmap=nn[KMG]@ss[KMG]
1382 [KNL] Force usage of a specific region of memory
1383 Region of memory to be used, from ss to ss+nn.
1384
1385 memmap=nn[KMG]#ss[KMG]
1386 [KNL,ACPI] Mark specific memory as ACPI data.
1387 Region of memory to be used, from ss to ss+nn.
1388
1389 memmap=nn[KMG]$ss[KMG]
1390 [KNL,ACPI] Mark specific memory as reserved.
1391 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001392 Example: Exclude memory from 0x18690000-0x1869ffff
1393 memmap=64K$0x18690000
1394 or
1395 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001397 memory_corruption_check=0/1 [X86]
1398 Some BIOSes seem to corrupt the first 64k of
1399 memory when doing things like suspend/resume.
1400 Setting this option will scan the memory
1401 looking for corruption. Enabling this will
1402 both detect corruption and prevent the kernel
1403 from using the memory being corrupted.
1404 However, its intended as a diagnostic tool; if
1405 repeatable BIOS-originated corruption always
1406 affects the same memory, you can use memmap=
1407 to prevent the kernel from using that memory.
1408
1409 memory_corruption_check_size=size [X86]
1410 By default it checks for corruption in the low
1411 64k, making this memory unavailable for normal
1412 use. Use this parameter to scan for
1413 corruption in more or less memory.
1414
1415 memory_corruption_check_period=seconds [X86]
1416 By default it checks for corruption every 60
1417 seconds. Use this parameter to check at some
1418 other rate. 0 disables periodic checking.
1419
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001420 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001421 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001422 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001423 Specifies the number of memtest passes to be
1424 performed. Each pass selects another test
1425 pattern from a given set of patterns. Memtest
1426 fills the memory with this pattern, validates
1427 memory contents and reserves bad memory
1428 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001429
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 meye.*= [HW] Set MotionEye Camera parameters
1431 See Documentation/video4linux/meye.txt.
1432
Andres Salomon8f368812007-10-12 23:04:06 +02001433 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1434 Multi-Function General Purpose Timers on AMD Geode
1435 platforms.
1436
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001437 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1438 the BIOS has incorrectly applied a workaround. TinyBIOS
1439 version 0.98 is known to be affected, 0.99 fixes the
1440 problem by letting the user disable the workaround.
1441
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 mga= [HW,DRM]
1443
Randy Dunlap1c207f92008-11-19 15:36:16 -08001444 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1445 physical address is ignored.
1446
Michel Pollet39f45d72009-05-20 11:10:31 +01001447 mini2440= [ARM,HW,KNL]
1448 Format:[0..2][b][c][t]
1449 Default: "0tb"
1450 MINI2440 configuration specification:
1451 0 - The attached screen is the 3.5" TFT
1452 1 - The attached screen is the 7" TFT
1453 2 - The VGA Shield is attached (1024x768)
1454 Leaving out the screen size parameter will not load
1455 the TFT driver, and the framebuffer will be left
1456 unconfigured.
1457 b - Enable backlight. The TFT backlight pin will be
1458 linked to the kernel VESA blanking code and a GPIO
1459 LED. This parameter is not necessary when using the
1460 VGA shield.
1461 c - Enable the s3c camera interface.
1462 t - Reserved for enabling touchscreen support. The
1463 touchscreen support is not enabled in the mainstream
1464 kernel as of 2.6.30, a preliminary port can be found
1465 in the "bleeding edge" mini2440 support kernel at
1466 http://repo.or.cz/w/linux-2.6/mini2440.git
1467
Mel Gorman6b74ab92008-07-23 21:26:49 -07001468 mminit_loglevel=
1469 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1470 parameter allows control of the logging verbosity for
1471 the additional memory initialisation checks. A value
1472 of 0 disables mminit logging and a level of 4 will
1473 log everything. Information is printed at KERN_DEBUG
1474 so loglevel=8 may also need to be specified.
1475
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476 mousedev.tap_time=
1477 [MOUSE] Maximum time between finger touching and
1478 leaving touchpad surface for touch to be considered
1479 a tap and be reported as a left button click (for
1480 touchpads working in absolute mode only).
1481 Format: <msecs>
1482 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1483 reporting absolute coordinates, such as tablets
1484 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1485 reporting absolute coordinates, such as tablets
1486
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301487 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001488 is similar to kernelcore except it specifies the
1489 amount of memory used for migratable allocations.
1490 If both kernelcore and movablecore is specified,
1491 then kernelcore will be at *least* the specified
1492 value but may be more. If movablecore on its own
1493 is specified, the administrator must be careful
1494 that the amount of memory usable for all allocations
1495 is not too small.
1496
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 MTD_Partition= [MTD]
1498 Format: <name>,<region-number>,<size>,<offset>
1499
Randy Dunlapa9913042005-10-23 12:57:11 -07001500 MTD_Region= [MTD] Format:
1501 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502
1503 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001504 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001506 multitce=off [PPC] This parameter disables the use of the pSeries
1507 firmware feature for updating multiple TCE entries
1508 at a time.
1509
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001510 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1511
1512 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1513
1514 boundary - index of last SLC block on Flex-OneNAND.
1515 The remaining blocks are configured as MLC blocks.
1516 lock - Configure if Flex-OneNAND boundary should be locked.
1517 Once locked, the boundary cannot be changed.
1518 1 indicates lock status, 0 indicates unlock status.
1519
Ben Dooks9db829f2008-07-03 11:24:29 +01001520 mtdset= [ARM]
1521 ARM/S3C2412 JIVE boot control
1522
1523 See arch/arm/mach-s3c2412/mach-jive.c
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001526 [HW] Make the MicroTouch USB driver use raw coordinates
1527 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001529 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001530 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001531 that could hold holes aka. UC entries.
1532
1533 mtrr_gran_size=nn[KMG] [X86]
1534 Used for mtrr cleanup. It is granularity of mtrr block.
1535 Default is 1.
1536 Large value could prevent small alignment from
1537 using up MTRRs.
1538
1539 mtrr_spare_reg_nr=n [X86]
1540 Format: <integer>
1541 Range: 0,7 : spare reg number
1542 Default : 1
1543 Used for mtrr cleanup. It is spare mtrr entries number.
1544 Set to 2 or more if your graphical card needs more.
1545
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 netdev= [NET] Network devices parameters
1549 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1550 Note that mem_start is often overloaded to mean
1551 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001552 This usage is only documented in each driver source
1553 file if at all.
1554
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001555 nf_conntrack.acct=
1556 [NETFILTER] Enable connection tracking flow accounting
1557 0 to disable accounting
1558 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001559 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001560
Chuck Lever306a0752010-09-17 10:54:37 -04001561 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001562 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563
1564 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001565 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566
Chuck Lever306a0752010-09-17 10:54:37 -04001567 nfsrootdebug [NFS] enable nfsroot debugging messages.
1568 See Documentation/filesystems/nfs/nfsroot.txt.
1569
Trond Myklebusta72b4422006-01-03 09:55:41 +01001570 nfs.callback_tcpport=
1571 [NFS] set the TCP port on which the NFSv4 callback
1572 channel should listen.
1573
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001574 nfs.cache_getent=
1575 [NFS] sets the pathname to the program which is used
1576 to update the NFS client cache entries.
1577
1578 nfs.cache_getent_timeout=
1579 [NFS] sets the timeout after which an attempt to
1580 update a cache entry is deemed to have failed.
1581
Trond Myklebust58df0952006-01-03 09:55:57 +01001582 nfs.idmap_cache_timeout=
1583 [NFS] set the maximum lifetime for idmapper cache
1584 entries.
1585
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001586 nfs.enable_ino64=
1587 [NFS] enable 64-bit inode numbers.
1588 If zero, the NFS client will fake up a 32-bit inode
1589 number for the readdir() and stat() syscalls instead
1590 of returning the full 64-bit number.
1591 The default is to return 64-bit inode numbers.
1592
Trond Myklebustb064eca22011-02-22 15:44:32 -08001593 nfs.nfs4_disable_idmapping=
1594 [NFSv4] When set, this option disables the NFSv4
1595 idmapper on the client, but only if the mount
1596 is using the 'sec=sys' security flavour. This may
1597 make migration from legacy NFSv2/v3 systems easier
1598 provided that the server has the appropriate support.
1599 The default is to always enable NFSv4 idmapping.
1600
Paul Mundt1e1030d2009-09-01 17:38:32 +09001601 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001602 when a NMI is triggered.
1603 Format: [state][,regs][,debounce][,die]
1604
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301605 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001606 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001607 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001608 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001609 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001610 timeout occurs (or 'nopanic' to override the opposite
1611 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001612 This is useful when you use a panic=... timeout and
1613 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614
Anton Vorontsovbff38772009-07-08 11:10:56 -07001615 netpoll.carrier_timeout=
1616 [NET] Specifies amount of time (in seconds) that
1617 netpoll should wait for a carrier. By default netpoll
1618 waits 4 seconds.
1619
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001620 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621 emulation library even if a 387 maths coprocessor
1622 is present.
1623
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001624 no_console_suspend
1625 [HW] Never suspend the console
1626 Disable suspending of consoles during suspend and
1627 hibernate operations. Once disabled, debugging
1628 messages can reach various consoles while the rest
1629 of the system is being put to sleep (ie, while
1630 debugging driver suspend/resume hooks). This may
1631 not work reliably with all consoles, but is known
1632 to work with serial and VGA consoles.
1633
Christoph Lameterc1aee212007-05-31 00:40:47 -07001634 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1635 caches in the slab allocator. Saves per-node memory,
1636 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001637
Randy Dunlapa9913042005-10-23 12:57:11 -07001638 noalign [KNL,ARM]
1639
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 noapic [SMP,APIC] Tells the kernel to not make use of any
1641 IOAPICs that may be present in the system.
1642
Mike Galbraith5091faa2010-11-30 14:18:03 +01001643 noautogroup Disable scheduler automatic task group creation.
1644
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 nobats [PPC] Do not use BATs for mapping kernel lowmem
1646 on "Classic" PPC cores.
1647
1648 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001649
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001650 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1651
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001652 nodelayacct [KNL] Disable per-task delay accounting
1653
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1655
Paul Mundt6902aa82008-09-21 17:14:42 +09001656 nodsp [SH] Disable hardware DSP at boot time.
1657
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301658 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 noexec [IA-64]
1661
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301662 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001663 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001665 noexec=off: disable non-executable mappings
1666
1667 noexec32 [X86-64]
1668 This affects only 32-bit executables.
1669 noexec32=on: enable non-executable mappings (default)
1670 read doesn't imply executable mappings
1671 noexec32=off: disable non-executable mappings
1672 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673
Paul Mundt6902aa82008-09-21 17:14:42 +09001674 nofpu [SH] Disable hardware FPU at boot time.
1675
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001676 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001677 register save and restore. The kernel will only save
1678 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679
Suresh Siddha0c752a92009-05-22 12:17:45 -07001680 noxsave [BUGS=X86] Disables x86 extended register state save
1681 and restore using xsave. The kernel will fallback to
1682 enabling legacy floating-point and sse state.
1683
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001684 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1685 wfi(ARM) instruction doesn't work correctly and not to
1686 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001687
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001688 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 instruction doesn't work correctly and not to
1690 use it.
1691
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001692 no_file_caps Tells the kernel not to honor file capabilities. The
1693 only way then for a file to be executed with privilege
1694 is to be setuid root or executed by root.
1695
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 nohalt [IA-64] Tells the kernel not to use the power saving
1697 function PAL_HALT_LIGHT when idle. This increases
1698 power-consumption. On the positive side, it reduces
1699 interrupt wake-up latency, which may improve performance
1700 in certain environments such as networked servers or
1701 real-time systems.
1702
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001703 nohz= [KNL] Boottime enable/disable dynamic ticks
1704 Valid arguments: on, off
1705 Default: on
1706
Paul Mundteeee7852009-04-02 12:31:16 +09001707 noiotrap [SH] Disables trapped I/O port accesses.
1708
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001709 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710 disable unhandled interrupt sources.
1711
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301712 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001713 broken timer IRQ sources.
1714
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 noisapnp [ISAPNP] Disables ISA PnP code.
1716
1717 noinitrd [RAM] Tells the kernel not to load any configured
1718 initial RAM disk.
1719
Weidong Han03ea8152009-04-17 16:42:15 +08001720 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1721 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001722 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001723
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724 nointroute [IA-64]
1725
Tony Luck0aa366f2007-07-20 11:22:30 -07001726 nojitter [IA64] Disables jitter checking for ITC timers.
1727
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001728 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1729
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001730 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1731 fault handling.
1732
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001733 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001735 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001736
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 noltlbs [PPC] Do not use large page/tlb entries for kernel
1738 lowmem mapping on PPC40x.
1739
Horms312f1f02006-02-22 09:57:55 +09001740 nomca [IA-64] Disable machine check abort handling
1741
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001742 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001743
Andres Salomon83d73842007-10-12 23:04:06 +02001744 nomfgpt [X86-32] Disable Multi-Function General Purpose
1745 Timer usage (for AMD Geode machines).
1746
Jiri Kosina016ddd92010-01-18 17:05:40 +01001747 nopat [X86] Disable PAT (page attribute table extension of
1748 pagetables) support.
1749
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001750 norandmaps Don't use address space randomization. Equivalent to
1751 echo 0 > /proc/sys/kernel/randomize_va_space
1752
Jiri Kosinabbff2162010-08-11 18:34:09 +02001753 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001754
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001755 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001756 with UP alternatives
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 noresidual [PPC] Don't use residual data on PReP machines.
1759
Randy Dunlapa9913042005-10-23 12:57:11 -07001760 noresume [SWSUSP] Disables resume and restores original swap
1761 space.
1762
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 no-scroll [VGA] Disables scrollback.
1764 This is required for the Braillex ib80-piezo Braille
1765 reader made by F.H. Papenmeier (Germany).
1766
1767 nosbagart [IA-64]
1768
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001769 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001770
Len Brown61ec7562007-08-16 03:34:22 -04001771 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1772 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773
Dave Jones97842212007-07-15 23:41:05 -07001774 nosoftlockup [KNL] Disable the soft-lockup detector.
1775
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001776 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001777 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001778
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 nosync [HW,M68K] Disables sync negotiation for all devices.
1780
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001781 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782
1783 nousb [USB] Disable the USB subsystem
1784
Ben Hutchings55142372011-01-02 23:02:42 +00001785 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001786
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001788
Weidong Han2b2fd872009-04-17 16:42:12 +08001789 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1790
Fenghua Yua6c75b862008-03-14 13:57:08 -07001791 nptcg= [IA64] Override max number of concurrent global TLB
1792 purges which is reported from either PAL_VM_SUMMARY or
1793 SAL PALO.
1794
Yinghai Lu2b633e32010-02-10 01:20:37 -08001795 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1796 could support. nr_cpus=n : n >= 1 limits the kernel to
1797 supporting 'n' processors. Later in runtime you can not
1798 use hotplug cpu feature to put more cpu back to online.
1799 just like you compile the kernel NR_CPUS=n
1800
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001801 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1802
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001803 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1804 one of ['zone', 'node', 'default'] can be specified
1805 This can be set from sysctl after boot.
1806 See Documentation/sysctl/vm.txt for details.
1807
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001808 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1809 See Documentation/debugging-via-ohci1394.txt for more
1810 info.
1811
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001812 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1813 Rather than timing out after 20 ms if an EC
1814 command is not properly ACKed, override the length
1815 of the timeout. We have interrupts disabled while
1816 waiting for the ACK, so if this is set too high
1817 interrupts *may* be lost!
1818
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001819 omap_mux= [OMAP] Override bootloader pin multiplexing.
1820 Format: <mux_mode0.mode_name=value>...
1821 For example, to override I2C bus2:
1822 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1823
Linus Torvalds1da177e2005-04-16 15:20:36 -07001824 oprofile.timer= [HW]
1825 Use timer interrupt instead of performance counters
1826
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001827 oprofile.cpu_type= Force an oprofile cpu type
1828 This might be useful if you have an older oprofile
1829 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001830 Format: { arch_perfmon }
1831 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001832 perfmon on Intel CPUs instead of the
1833 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001834
Olaf Heringd404ab02011-03-22 16:34:04 -07001835 oops=panic Always panic on oopses. Default is to just kill the process,
1836 but there is a small probability of deadlocking the machine.
1837 This will also cause panics on machine check exceptions.
1838 Useful together with panic=30 to trigger a reboot.
1839
Randy Dunlapbcfde332010-06-07 17:10:38 -07001840 OSS [HW,OSS]
1841 See Documentation/sound/oss/oss-parameters.txt
1842
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 panic= [KNL] Kernel behaviour on panic
1844 Format: <timeout>
1845
1846 parkbd.port= [HW] Parallel port number the keyboard adapter is
1847 connected to, default is 0.
1848 Format: <parport#>
1849 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1850 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001851 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852
Randy Dunlapa9913042005-10-23 12:57:11 -07001853 parport= [HW,PPT] Specify parallel ports. 0 disables.
1854 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1855 Use 'auto' to force the driver to use any
1856 IRQ/DMA settings detected (the default is to
1857 ignore detected IRQ/DMA settings because of
1858 possible conflicts). You can specify the base
1859 address, IRQ, and DMA settings; IRQ and DMA
1860 should be numbers, or 'auto' (for using detected
1861 settings on that particular port), or 'nofifo'
1862 (to avoid using a FIFO even if it is detected).
1863 Parallel ports are assigned in the order they
1864 are specified on the command line, starting
1865 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866
Randy Dunlapa9913042005-10-23 12:57:11 -07001867 parport_init_mode= [HW,PPT]
1868 Configure VIA parallel port to operate in
1869 a specific mode. This is necessary on Pegasos
1870 computer where firmware has no options for setting
1871 up parallel port mode and sets it to spp.
1872 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 Format: [spp|ps2|epp|ecp|ecpepp]
1874
Andrew Mortondd287792006-03-23 03:00:57 -08001875 pause_on_oops=
1876 Halt all CPUs after the first oops has been printed for
1877 the specified number of seconds. This is to be used if
1878 your oopses keep scrolling off the screen.
1879
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 pcbit= [HW,ISDN]
1881
1882 pcd. [PARIDE]
1883 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001884 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885
Randy Dunlapa9913042005-10-23 12:57:11 -07001886 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001887 earlydump [X86] dump PCI config space before the kernel
1888 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001889 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001890 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001891 the hardware directly. Use this if your machine
1892 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001893 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001894 hardware access methods are allowed. Use this
1895 if you experience crashes upon bootup and you
1896 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001897 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001898 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001899 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001900 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001901 noaer [PCIE] If the PCIEAER kernel config parameter is
1902 enabled, this kernel boot option can be used to
1903 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001904 nodomains [PCI] Disable support for multiple PCI
1905 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301906 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001907 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001908 check_enable_amd_mmconf [X86] check for and enable
1909 properly configured MMIO access to PCI
1910 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001911 nomsi [MSI] If the PCI_MSI kernel config parameter is
1912 enabled, this kernel boot option can be used to
1913 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001914 noioapicquirk [APIC] Disable all boot interrupt quirks.
1915 Safety option to keep boot IRQs enabled. This
1916 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001917 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1918 primary IO-APIC for bridges that cannot disable
1919 boot IRQs. This fixes a source of spurious IRQs
1920 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001921 noioapicreroute [APIC] Disable workaround that uses the
1922 boot IRQ equivalent of an IRQ that connects to
1923 a chipset where boot IRQs cannot be disabled.
1924 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001925 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001926 routing table. These calls are known to be buggy
1927 on several machines and they hang the machine
1928 when used, but on other computers it's the only
1929 way to get the interrupt routing table. Try
1930 this option if the kernel is unable to allocate
1931 IRQs or discover secondary PCI buses on your
1932 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001933 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001934 Use with caution as certain devices share
1935 address decoders between ROMs and other
1936 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001937 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001938 expansion ROMs that do not already have
1939 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07001940 nobar [X86] Do not assign address space to the
1941 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001942 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001943 assigned automatically to PCI devices. You can
1944 make the kernel exclude IRQs of your ISA cards
1945 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001946 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001947 of the PIRQ table (normally generated
1948 by the BIOS) if it is outside the
1949 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001950 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001951 useful if the kernel is unable to find your
1952 secondary buses and you want to tell it
1953 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001954 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001955 numbers ourselves, overriding
1956 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001957 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001958 in the BIOS $PIR table. This is needed on
1959 some systems with broken BIOSes, notably
1960 some HP Pavilion N5400 and Omnibook XE3
1961 notebooks. This will have no effect if ACPI
1962 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001963 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001964 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001965 use_crs [X86] Use PCI host bridge window information
1966 from ACPI. On BIOSes from 2008 or later, this
1967 is enabled by default. If you need to use this,
1968 please report a bug.
1969 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1970 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001971 routeirq Do IRQ routing for all PCI devices.
1972 This is normally done in pci_enable_device(),
1973 so this option is a temporary workaround
1974 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001975 skip_isa_align [X86] do not align io start addr, so can
1976 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001977 firmware [ARM] Do not re-enumerate the bus but instead
1978 just use the configuration from the
1979 bootloader. This is currently used on
1980 IXP2000 systems where the bus has to be
1981 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001982 noearly [X86] Don't do any early type 1 scanning.
1983 This might help on some broken boards which
1984 machine check when some devices' config space
1985 is read. But various workarounds are disabled
1986 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001987 bfsort Sort PCI devices into breadth-first order.
1988 This sorting is done to get a device
1989 order compatible with older (<= 2.4) kernels.
1990 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001991 cbiosize=nn[KMG] The fixed amount of bus space which is
1992 reserved for the CardBus bridge's IO window.
1993 The default value is 256 bytes.
1994 cbmemsize=nn[KMG] The fixed amount of bus space which is
1995 reserved for the CardBus bridge's memory
1996 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09001997 resource_alignment=
1998 Format:
1999 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2000 Specifies alignment and device to reassign
2001 aligned memory resources.
2002 If <order of align> is not specified,
2003 PAGE_SIZE is used as alignment.
2004 PCI-PCI bridge can be specified, if resource
2005 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002006 ecrc= Enable/disable PCIe ECRC (transaction layer
2007 end-to-end CRC checking).
2008 bios: Use BIOS/firmware settings. This is the
2009 the default.
2010 off: Turn ECRC off
2011 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002012
Chuck Ebberte5665a42008-09-24 20:40:34 -04002013 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2014 Management.
2015 off Disable ASPM.
2016 force Enable ASPM even on devices that claim not to support it.
2017 WARNING: Forcing ASPM on may cause system lockups.
2018
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002019 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002020 auto Ask the BIOS whether or not to use native PCIe services
2021 associated with PCIe ports (PME, hot-plug, AER). Use
2022 them only if that is allowed by the BIOS.
2023 native Use native PCIe services associated with PCIe ports
2024 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002025 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2026 ports driver.
2027
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002028 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002029 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002030 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 pcmv= [HW,PCMCIA] BadgePAD 4
2033
2034 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002035 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036
2037 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2038 boot time.
2039 Format: { 0 | 1 }
2040 See arch/parisc/kernel/pdc_chassis.c
2041
Tejun Heof58dc012009-08-14 15:00:50 +09002042 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002043 Currently supported values are "embed" and "page".
2044 Archs may support subset or none of the selections.
2045 See comments in mm/percpu.c for details on each
2046 allocator. This parameter is primarily for debugging
2047 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002050 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051
2052 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002053 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054
2055 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002056 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057
2058 plip= [PPT,NET] Parallel port network link
2059 Format: { parport<nr> | timid | 0 }
2060 See also Documentation/parport.txt.
2061
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002062 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2063 Override pmtimer IOPort with a hex value.
2064 e.g. pmtmr=0x508
2065
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002066 pnp.debug [PNP]
2067 Enable PNP debug messages. This depends on the
2068 CONFIG_PNP_DEBUG_MESSAGES option.
2069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 pnpacpi= [ACPI]
2071 { off }
2072
2073 pnpbios= [ISAPNP]
2074 { on | off | curr | res | no-curr | no-res }
2075
2076 pnp_reserve_irq=
2077 [ISAPNP] Exclude IRQs for the autoconfiguration
2078
2079 pnp_reserve_dma=
2080 [ISAPNP] Exclude DMAs for the autoconfiguration
2081
2082 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002083 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084
2085 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002086 [ISAPNP] Exclude memory regions for the
2087 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088 Ranges are in pairs (memory base and size).
2089
Randy Dunlap4af94f32009-04-17 18:30:28 -07002090 ports= [IP_VS_FTP] IPVS ftp helper module
2091 Default is 21.
2092 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2093 may be specified.
2094 Format: <port>,<port>....
2095
Ingo Molnar45807a12007-07-15 23:40:10 -07002096 print-fatal-signals=
2097 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002098
2099 If enabled, warn about various signal handling
2100 related application anomalies: too many signals,
2101 too many POSIX.1 timers, fatal signals causing a
2102 coredump - etc.
2103
2104 If you hit the warning due to signal overflow,
2105 you might want to try "ulimit -i unlimited".
2106
Ingo Molnar45807a12007-07-15 23:40:10 -07002107 default: off.
2108
Randy Dunlape84845c2007-07-15 23:40:25 -07002109 printk.time= Show timing data prefixed to each printk message line
2110 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2111
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002112 processor.max_cstate= [HW,ACPI]
2113 Limit processor to maximum C-state
2114 max_cstate=9 overrides any DMI blacklist limit.
2115
2116 processor.nocst [HW,ACPI]
2117 Ignore the _CST method to determine C-states,
2118 instead using the legacy FADT method
2119
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002121 Format: [schedule,]<number>
2122 Param: "schedule" - profile schedule points.
2123 Param: <number> - step/bucket size as a power of 2 for
2124 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002125 Param: "sleep" - profile D-state sleeping (millisecs).
2126 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002127 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2130 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002131 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132
Randy Dunlapa9913042005-10-23 12:57:11 -07002133 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2134 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2136 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002137 psmouse.resetafter= [HW,MOUSE]
2138 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 (0 = never).
2140 psmouse.resolution=
2141 [HW,MOUSE] Set desired mouse resolution, in dpi.
2142 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002143 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 0 = disabled, 1 = enabled (default).
2145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002147 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148
Kay Sieversdc8c8582007-08-15 12:25:38 +02002149 pty.legacy_count=
2150 [KNL] Number of legacy pty's. Overwrites compiled-in
2151 default number.
2152
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002153 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 r128= [HW,DRM]
2156
2157 raid= [HW,RAID]
2158 See Documentation/md.txt.
2159
Randy Dunlapa9913042005-10-23 12:57:11 -07002160 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002161 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002162
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002164 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002166 rcupdate.blimit= [KNL,BOOT]
2167 Set maximum number of finished RCU callbacks to process
2168 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002169
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002170 rcupdate.qhimark= [KNL,BOOT]
2171 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002172 RCU callbacks over which batch limiting is disabled.
2173
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002174 rcupdate.qlowmark= [KNL,BOOT]
2175 Set threshold of queued RCU callbacks below which
2176 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002177
Olof Johanssonffdfc402005-09-06 15:17:19 -07002178 rdinit= [KNL]
2179 Format: <full_path>
2180 Run specified binary instead of /init from the ramdisk,
2181 used for early userspace startup. See initrd.
2182
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002183 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002185 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186
Paul Jackson46b6d942008-07-04 10:00:09 -07002187 relax_domain_level=
2188 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002189 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002190
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2192
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002193 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002194 Format: nn[KMG]
2195 Reserves a hole at the top of the kernel virtual
2196 address space.
2197
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002198 reservelow= [X86]
2199 Format: nn[K]
2200 Set the amount of memory to reserve for BIOS at
2201 the bottom of the address space.
2202
Vivek Goyal7e962872006-09-27 01:50:44 -07002203 reset_devices [KNL] Force drivers to reset the underlying device
2204 during initialization.
2205
Randy Dunlapa9913042005-10-23 12:57:11 -07002206 resume= [SWSUSP]
2207 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002208
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002209 resume_offset= [SWSUSP]
2210 Specify the offset from the beginning of the partition
2211 given by "resume=" at which the swap header is located,
2212 in <PAGE_SIZE> units (needed only for swap files).
2213 See Documentation/power/swsusp-and-swap-files.txt
2214
Bojan Smojverf996fc92010-09-09 23:06:23 +02002215 hibernate= [HIBERNATION]
2216 noresume Don't check if there's a hibernation image
2217 present during boot.
2218 nocompress Don't compress/decompress hibernation images.
2219
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002220 retain_initrd [RAM] Keep initrd memory after extraction
2221
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 rhash_entries= [KNL,NET]
2223 Set number of hash buckets for route cache
2224
2225 riscom8= [HW,SERIAL]
2226 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2227
2228 ro [KNL] Mount root device read-only on boot
2229
2230 root= [KNL] Root filesystem
2231
2232 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2233 mount the root filesystem
2234
2235 rootflags= [KNL] Set root filesystem mount option string
2236
2237 rootfstype= [KNL] Set root filesystem type
2238
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002239 rootwait [KNL] Wait (indefinitely) for root device to show up.
2240 Useful for devices that are detected asynchronously
2241 (e.g. USB and MMC devices).
2242
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243 rw [KNL] Mount root device read-write on boot
2244
2245 S [KNL] Run init in single mode
2246
2247 sa1100ir [NET]
2248 See drivers/net/irda/sa1100_ir.c.
2249
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002251
Mike Travisf6630112009-11-17 18:22:15 -06002252 sched_debug [KNL] Enables verbose scheduler debug messages.
2253
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002254 security= [SECURITY] Choose a security module to enable at boot.
2255 If this boot parameter is not specified, only the first
2256 security module asking for security registration will be
2257 loaded. An invalid security module name will be treated
2258 as if no module has been chosen.
2259
2260 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 Format: { "0" | "1" }
2262 See security/selinux/Kconfig help text.
2263 0 -- disable.
2264 1 -- enable.
2265 Default value is set via kernel config option.
2266 If enabled at boot time, /selinux/disable can be used
2267 later to disable prior to initial policy load.
2268
John Johansenc1c124e2010-07-29 14:48:09 -07002269 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2270 Format: { "0" | "1" }
2271 See security/apparmor/Kconfig help text
2272 0 -- disable.
2273 1 -- enable.
2274 Default value is set via kernel config option.
2275
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002276 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002277
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278 shapers= [NET]
2279 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002280
Yinghai Lub05f78f2008-08-22 01:32:50 -07002281 show_msr= [x86] show boot-time MSR settings
2282 Format: { <integer> }
2283 Show boot-time (BIOS-initialized) MSR settings.
2284 The parameter means the number of CPUs to show,
2285 for example 1 means boot CPU only.
2286
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287 simeth= [IA-64]
2288 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002289
Linus Torvalds1da177e2005-04-16 15:20:36 -07002290 slram= [HW,MTD]
2291
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002292 slub_debug[=options[,slabs]] [MM, SLUB]
2293 Enabling slub_debug allows one to determine the
2294 culprit if slab objects become corrupted. Enabling
2295 slub_debug can create guard zones around objects and
2296 may poison objects when not in use. Also tracks the
2297 last alloc / free. For more information see
2298 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002299
2300 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002301 Determines the maximum allowed order for slabs.
2302 A high setting may cause OOMs due to memory
2303 fragmentation. For more information see
2304 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002305
2306 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002307 The minimum number of objects per slab. SLUB will
2308 increase the slab order up to slub_max_order to
2309 generate a sufficiently large slab able to contain
2310 the number of objects indicated. The higher the number
2311 of objects the smaller the overhead of tracking slabs
2312 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002313 For more information see Documentation/vm/slub.txt.
2314
2315 slub_min_order= [MM, SLUB]
2316 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002317 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002318 For more information see Documentation/vm/slub.txt.
2319
2320 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002321 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002322 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002323 allocs to different slabs. Debug options disable
2324 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002325 For more information see Documentation/vm/slub.txt.
2326
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 smart2= [HW]
2328 Format: <io1>[,<io2>[,...,<io8>]]
2329
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002330 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002331 attempt to substitute SMP alternatives once at boot.
2332
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002333 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2334 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2335 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2336 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2337 smsc-ircc2.ircc_irq= [HW] IRQ line
2338 smsc-ircc2.ircc_dma= [HW] DMA channel
2339 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2340 0: Toshiba Satellite 1800 (GP data pin select)
2341 1: Fast pin select (default)
2342 2: ATC IRMode
2343
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002344 softlockup_panic=
2345 [KNL] Should the soft-lockup detector generate panics.
2346
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2348 See Documentation/sonypi.txt
2349
2350 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002351 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352
2353 spia_io_base= [HW,MTD]
2354 spia_fio_base=
2355 spia_pedr=
2356 spia_peddr=
2357
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002358 stacktrace [FTRACE]
2359 Enabled the stack tracer on boot up.
2360
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 sti= [PARISC,HW]
2362 Format: <num>
2363 Set the STI (builtin display/keyboard on the HP-PARISC
2364 machines) console (graphic card) which should be used
2365 as the initial boot-console.
2366 See also comment in drivers/video/console/sticore.c.
2367
2368 sti_font= [HW]
2369 See comment in drivers/video/console/sticore.c.
2370
2371 stifb= [HW]
2372 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2373
Trond Myklebustcbf11072009-08-09 15:06:19 -04002374 sunrpc.min_resvport=
2375 sunrpc.max_resvport=
2376 [NFS,SUNRPC]
2377 SunRPC servers often require that client requests
2378 originate from a privileged port (i.e. a port in the
2379 range 0 < portnr < 1024).
2380 An administrator who wishes to reserve some of these
2381 ports for other uses may adjust the range that the
2382 kernel's sunrpc client considers to be privileged
2383 using these two parameters to set the minimum and
2384 maximum port values.
2385
Greg Banks42a7fc42007-03-06 01:42:23 -08002386 sunrpc.pool_mode=
2387 [NFS]
2388 Control how the NFS server code allocates CPUs to
2389 service thread pools. Depending on how many NICs
2390 you have and where their interrupts are bound, this
2391 option will affect which CPUs will do NFS serving.
2392 Note: this parameter cannot be changed while the
2393 NFS server is running.
2394
2395 auto the server chooses an appropriate mode
2396 automatically using heuristics
2397 global a single global pool contains all CPUs
2398 percpu one pool for each CPU
2399 pernode one pool for each NUMA node (equivalent
2400 to global on non-NUMA machines)
2401
Trond Myklebustcbf11072009-08-09 15:06:19 -04002402 sunrpc.tcp_slot_table_entries=
2403 sunrpc.udp_slot_table_entries=
2404 [NFS,SUNRPC]
2405 Sets the upper limit on the number of simultaneous
2406 RPC calls that can be sent from the client to a
2407 server. Increasing these values may allow you to
2408 improve throughput, but will also increase the
2409 amount of memory reserved for use by the client.
2410
Michal Hockoa42c3902010-11-24 12:57:08 -08002411 swapaccount[=0|1]
2412 [KNL] Enable accounting of swap in memory resource
2413 controller if no parameter or 1 is given or disable
2414 it if 0 is given (See Documentation/cgroups/memory.txt)
2415
Linus Torvalds1da177e2005-04-16 15:20:36 -07002416 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002417
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418 switches= [HW,M68k]
2419
Andi Kleene52eec12010-09-08 16:54:17 +02002420 sysfs.deprecated=0|1 [KNL]
2421 Enable/disable old style sysfs layout for old udev
2422 on older distributions. When this option is enabled
2423 very new udev will not work anymore. When this option
2424 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2425 in older udev will not work anymore.
2426 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2427 the kernel configuration.
2428
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002429 sysrq_always_enabled
2430 [KNL]
2431 Ignore sysrq setting - this boot parameter will
2432 neutralize any effect of /proc/sys/kernel/sysrq.
2433 Useful for debugging.
2434
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 tdfx= [HW,DRM]
2436
David Brownell77437fd2008-07-23 21:28:33 -07002437 test_suspend= [SUSPEND]
2438 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2439 standby suspend) as the system sleep state to briefly
2440 enter during system startup. The system is woken from
2441 this state using a wakeup-capable RTC alarm.
2442
Linus Torvalds1da177e2005-04-16 15:20:36 -07002443 thash_entries= [KNL,NET]
2444 Set number of hash buckets for TCP connection
2445
Len Brownf8707ec2007-08-12 00:12:54 -04002446 thermal.act= [HW,ACPI]
2447 -1: disable all active trip points in all thermal zones
2448 <degrees C>: override all lowest active trip points
2449
Len Brownc52a7412007-08-14 15:49:32 -04002450 thermal.crt= [HW,ACPI]
2451 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002452 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002453
Len Brownf5487142007-08-12 00:12:44 -04002454 thermal.nocrt= [HW,ACPI]
2455 Set to disable actions on ACPI thermal zone
2456 critical and hot trip points.
2457
Len Brown72b33ef2007-08-12 00:12:17 -04002458 thermal.off= [HW,ACPI]
2459 1: disable ACPI thermal control
2460
Len Browna70cdc52007-08-12 00:12:35 -04002461 thermal.psv= [HW,ACPI]
2462 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002463 <degrees C>: override all passive trip points to this
2464 value
Len Browna70cdc52007-08-12 00:12:35 -04002465
Len Brown730ff342007-08-12 00:12:26 -04002466 thermal.tzp= [HW,ACPI]
2467 Specify global default ACPI thermal zone polling rate
2468 <deci-seconds>: poll all this frequency
2469 0: no polling (default)
2470
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002471 threadirqs [KNL]
2472 Force threading of all interrupt handlers except those
2473 marked explicitely IRQF_NO_THREAD.
2474
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002475 topology= [S390]
2476 Format: {off | on}
2477 Specify if the kernel should make use of the cpu
2478 topology informations if the hardware supports these.
2479 The scheduler will make use of these informations and
2480 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002481 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002482
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483 tp720= [HW,PS2]
2484
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002485 tpm_suspend_pcr=[HW,TPM]
2486 Format: integer pcr id
2487 Specify that at suspend time, the tpm driver
2488 should extend the specified pcr with zeros,
2489 as a workaround for some chips which fail to
2490 flush the last written pcr on TPM_SaveState.
2491 This will guarantee that all the other pcrs
2492 are saved.
2493
Li Zefan9d612be2009-06-24 17:33:15 +08002494 trace_buf_size=nn[KMG]
2495 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002496
Li Zefan020e5f82009-07-01 10:47:05 +08002497 trace_event=[event-list]
2498 [FTRACE] Set and start specified trace events in order
2499 to facilitate early boot debugging.
2500 See also Documentation/trace/events.txt
2501
john stultzd3b8f882009-08-17 16:40:47 -07002502 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002503 Format: <string>
2504 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002505 disables clocksource verification at runtime, as well
2506 as the stability checks done at bootup. Used to enable
2507 high-resolution timer mode on older hardware, and in
2508 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002509 [x86] noirqtime: Do not use TSC to do irq accounting.
2510 Used to run time disable IRQ_TIME_ACCOUNTING on any
2511 platforms where RDTSC is slow and this accounting
2512 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002513
Randy Dunlapa9913042005-10-23 12:57:11 -07002514 turbografx.map[2|3]= [HW,JOY]
2515 TurboGraFX parallel port interface
2516 Format:
2517 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518 See also Documentation/input/joystick-parport.txt
2519
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002520 uhash_entries= [KNL,NET]
2521 Set number of hash buckets for UDP/UDP-Lite connections
2522
Alan Stern5f8364b2006-12-05 16:29:55 -05002523 uhci-hcd.ignore_oc=
2524 [USB] Ignore overcurrent events (default N).
2525 Some badly-designed motherboards generate lots of
2526 bogus events, for ports that aren't wired to
2527 anything. Set this parameter to avoid log spamming.
2528 Note that genuine overcurrent events won't be
2529 reported either.
2530
Simon Arlotte3a61b02008-07-19 23:32:54 +01002531 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302532 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002533 Set unknown_nmi_panic=1 early on boot.
2534
Alan Sternb5e795f2007-02-20 15:00:53 -05002535 usbcore.autosuspend=
2536 [USB] The autosuspend time delay (in seconds) used
2537 for newly-detected USB devices (default 2). This
2538 is the time required before an idle device will be
2539 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002540 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002541
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002542 usbcore.usbfs_snoop=
2543 [USB] Set to log all usbfs traffic (default 0 = off).
2544
2545 usbcore.blinkenlights=
2546 [USB] Set to cycle leds on hubs (default 0 = off).
2547
2548 usbcore.old_scheme_first=
2549 [USB] Start with the old device initialization
2550 scheme (default 0 = off).
2551
2552 usbcore.use_both_schemes=
2553 [USB] Try the other device initialization scheme
2554 if the first one fails (default 1 = enabled).
2555
2556 usbcore.initial_descriptor_timeout=
2557 [USB] Specifies timeout for the initial 64-byte
2558 USB_REQ_GET_DESCRIPTOR request in milliseconds
2559 (default 5000 = 5.0 seconds).
2560
Linus Torvalds1da177e2005-04-16 15:20:36 -07002561 usbhid.mousepoll=
2562 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002563
Alan Sternd4f373e2008-11-10 14:07:45 -05002564 usb-storage.delay_use=
2565 [UMS] The delay in seconds before a new device is
2566 scanned for Logical Units (default 5).
2567
2568 usb-storage.quirks=
2569 [UMS] A list of quirks entries to supplement or
2570 override the built-in unusual_devs list. List
2571 entries are separated by commas. Each entry has
2572 the form VID:PID:Flags where VID and PID are Vendor
2573 and Product ID values (4-digit hex numbers) and
2574 Flags is a set of characters, each corresponding
2575 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002576 a = SANE_SENSE (collect more than 18 bytes
2577 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002578 b = BAD_SENSE (don't collect more than 18
2579 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002580 c = FIX_CAPACITY (decrease the reported
2581 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002582 h = CAPACITY_HEURISTICS (decrease the
2583 reported device capacity by one
2584 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002585 i = IGNORE_DEVICE (don't bind to this
2586 device);
2587 l = NOT_LOCKABLE (don't try to lock and
2588 unlock ejectable media);
2589 m = MAX_SECTORS_64 (don't transfer more
2590 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002591 o = CAPACITY_OK (accept the capacity
2592 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002593 r = IGNORE_RESIDUE (the device reports
2594 bogus residue values);
2595 s = SINGLE_LUN (the device has only one
2596 Logical Unit);
2597 w = NO_WP_DETECT (don't test whether the
2598 medium is write-protected).
2599 Example: quirks=0419:aaf5:rl,0421:0433:rc
2600
Ian Campbell14315592010-02-17 10:38:10 +00002601 userpte=
2602 [X86] Flags controlling user PTE allocations.
2603
2604 nohigh = do not allocate PTE pages in
2605 HIGHMEM regardless of setting
2606 of CONFIG_HIGHPTE.
2607
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302608 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002609 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002610 vdso=1: enable VDSO (default)
2611 vdso=0: disable VDSO mapping
2612
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302613 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002614 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2615 vdso32=1: enable 32-bit VDSO (default)
2616 vdso32=0: disable 32-bit VDSO mapping
2617
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002618 vector= [IA-64,SMP]
2619 vector=percpu: enable percpu vector domain
2620
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621 video= [FB] Frame buffer configuration
2622 See Documentation/fb/modedb.txt.
2623
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002624 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002625 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002626 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002627 Use vga=ask for menu.
2628 This is actually a boot loader parameter; the value is
2629 passed to the kernel using a special protocol.
2630
Randy Dunlapa9913042005-10-23 12:57:11 -07002631 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002632 size of <nn>. This can be used to increase the
2633 minimum size (128MB on x86). It can also be used to
2634 decrease the size and leave more room for directly
2635 mapped kernel RAM.
2636
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002637 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2638 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002640 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2641 Format: <command>
2642
2643 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2644 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002645
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002646 vt.cur_default= [VT] Default cursor shape.
2647 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2648 the parameters of the <Esc>[?A;B;Cc escape sequence;
2649 see VGA-softcursor.txt. Default: 2 = underline.
2650
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002651 vt.default_blu= [VT]
2652 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2653 Change the default blue palette of the console.
2654 This is a 16-member array composed of values
2655 ranging from 0-255.
2656
2657 vt.default_grn= [VT]
2658 Format: <green0>,<green1>,<green2>,...,<green15>
2659 Change the default green palette of the console.
2660 This is a 16-member array composed of values
2661 ranging from 0-255.
2662
2663 vt.default_red= [VT]
2664 Format: <red0>,<red1>,<red2>,...,<red15>
2665 Change the default red palette of the console.
2666 This is a 16-member array composed of values
2667 ranging from 0-255.
2668
2669 vt.default_utf8=
2670 [VT]
2671 Format=<0|1>
2672 Set system-wide default UTF-8 mode for all tty's.
2673 Default is 1, i.e. UTF-8 mode is enabled for all
2674 newly opened terminals.
2675
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002676 vt.global_cursor_default=
2677 [VT]
2678 Format=<-1|0|1>
2679 Set system-wide default for whether a cursor
2680 is shown on new VTs. Default is -1,
2681 i.e. cursors will be created by default unless
2682 overridden by individual drivers. 0 will hide
2683 cursors, 1 will display them.
2684
Randy Dunlap4724ba572010-05-03 11:42:52 -07002685 watchdog timers [HW,WDT] For information on watchdog timers,
2686 see Documentation/watchdog/watchdog-parameters.txt
2687 or other driver-specific files in the
2688 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002689
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002690 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2691 default x2apic cluster mode on platforms
2692 supporting x2apic.
2693
Jacob Panbb24c472009-09-02 07:37:17 -07002694 x86_mrst_timer= [X86-32,APBT]
2695 Choose timer option for x86 Moorestown MID platform.
2696 Two valid options are apbt timer only and lapic timer
2697 plus one apbt timer for broadcast timer.
2698 x86_mrst_timer=apbt_only | lapic_and_apbt
2699
Linus Torvalds1da177e2005-04-16 15:20:36 -07002700 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2701 xd_geo= See header of drivers/block/xd.c.
2702
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002703 xen_emul_unplug= [HW,X86,XEN]
2704 Unplug Xen emulated devices
2705 Format: [unplug0,][unplug1]
2706 ide-disks -- unplug primary master IDE devices
2707 aux-ide-disks -- unplug non-primary-master IDE devices
2708 nics -- unplug network devices
2709 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002710 unnecessary -- unplugging emulated devices is
2711 unnecessary even if the host did not respond to
2712 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002713 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002714
Linus Torvalds1da177e2005-04-16 15:20:36 -07002715 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002716 Format:
2717 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002718
Randy Dunlapa9913042005-10-23 12:57:11 -07002719______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002720
2721TODO:
2722
Linus Torvalds1da177e2005-04-16 15:20:36 -07002723 Add more DRM drivers.