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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Alan Cox9cfe2682011-01-25 14:18:38 +000046 DRM Direct Rendering Management support is enabled.
47 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
49 EFI EFI Partitioning (GPT) is enabled
50 EIDE EIDE/ATAPI support is enabled.
51 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070052 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050055 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070057 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080058 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 ISAPNP ISA PnP code is enabled.
60 ISDN Appropriate ISDN support is enabled.
61 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050062 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020063 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070064 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 LP Printer support is enabled.
66 LOOP Loopback device support is enabled.
67 M68k M68k architecture is enabled.
68 These options have more detailed description inside of
69 Documentation/m68k/kernel-options.txt.
70 MCA MCA bus support is enabled.
71 MDA MDA console support is enabled.
72 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070073 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070074 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 NET Appropriate network support is enabled.
76 NUMA NUMA support is enabled.
77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070079 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070083 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
Randy Dunlap163475f2010-08-14 12:36:14 -070092 A lot of drivers have their options described inside
93 the Documentation/scsi/ sub-directory.
James Morris20510f22007-10-16 23:31:32 -070094 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 SELINUX SELinux support is enabled.
John Johansenc1c124e2010-07-29 14:48:09 -070096 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090098 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500103 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300104 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500106 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700114 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700117 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100119 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121In addition, the following text indicates that the option:
122
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
126
127Parameters denoted with BOOT are actually interpreted by the boot
128loader, and have no meaning to the kernel directly.
129Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500130need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Karsten Weiss55588702007-02-13 13:26:21 +0100132There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700133See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100134
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136a trailing = on the name of any parameter states that that parameter will
137be entered as an environment variable, whereas its absence indicates that
138it will appear as a kernel argument readable via /proc/cmdline by programs
139running once the system is up.
140
jens m. noedler9c4751f2006-09-29 02:00:27 -0700141The number of kernel parameters is not limited, but the length of the
142complete command line (parameters including spaces etc.) is limited to
143a fixed number of characters. This limit depends on the architecture
144and is between 256 and 4096 characters. It is defined in the file
145./include/asm/setup.h as COMMAND_LINE_SIZE.
146
Ahmed S. Darwish7a19a232011-02-20 20:08:35 -0800147Finally, the [KMG] suffix is commonly described after a number of kernel
148parameter values. These 'K', 'M', and 'G' letters represent the _binary_
149multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
150bytes respectively. Such letter suffixes can also be entirely omitted.
151
jens m. noedler9c4751f2006-09-29 02:00:27 -0700152
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530153 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800154 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500155 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 force -- enable ACPI if default was off
157 off -- disable ACPI if default was on
158 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700159 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800161 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800162 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163
Randy Dunlap53471122008-03-12 18:10:51 -0400164 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Len Browna1fdcc02007-03-11 03:26:14 -0400166 acpi_apic_instance= [ACPI, IOAPIC]
167 Format: <int>
168 2: use 2nd APIC table, if available
169 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400170 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400171
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200172 acpi_backlight= [HW,ACPI]
173 acpi_backlight=vendor
174 acpi_backlight=video
175 If set to vendor, prefer vendor specific driver
176 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
177 of the ACPI video.ko driver.
178
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700179 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
180 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700182 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
183 debug output. Bits in debug_layer correspond to a
184 _COMPONENT in an ACPI source file, e.g.,
185 #define _COMPONENT ACPI_PCI_COMPONENT
186 Bits in debug_level correspond to a level in
187 ACPI_DEBUG_PRINT statements, e.g.,
188 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600189 The debug_level mask defaults to "info". See
190 Documentation/acpi/debug.txt for more information about
191 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600193 Enable processor driver info messages:
194 acpi.debug_layer=0x20000000
195 Enable PCI/PCI interrupt routing info messages:
196 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700197 Enable AML "Debug" output, i.e., stores to the Debug
198 object while interpreting AML:
199 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700200 Enable all messages related to ACPI hardware:
201 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200202
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700203 Some values produce so much output that the system is
204 unusable. The "log_buf_len" parameter may be useful
205 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800206
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
209 default in APIC mode
210
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
213 default in PIC mode
214
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
217
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
219 use by PCI
220 Format: <irq>,<irq>...
221
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
226
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
231
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530232 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
236
Randy Dunlap4af94f32009-04-17 18:30:28 -0700237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
239
240 acpi_serialize [HW,ACPI] force serialization of AML methods
241
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
245
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Amerigo Wangc3b07952011-05-10 21:09:38 +0200248 old_ordering, nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700249 See Documentation/power/video.txt for information on
250 s3_bios and s3_mode.
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200259 nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700264
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
268
Luca Tettamanti7e905602009-03-30 00:01:27 +0200269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
284
Randy Dunlap4af94f32009-04-17 18:30:28 -0700285 add_efi_memmap [EFI; X86] Include EFI memory map in
286 kernel's map of available physical RAM.
287
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700288 agp= [AGP]
289 { off | try_unsupported }
290 off: disable AGP support
291 try_unsupported: try to drive unsupported chipsets
292 (may crash computer or cause data corruption)
293
Randy Dunlapbcfde332010-06-07 17:10:38 -0700294 ALSA [HW,ALSA]
295 See Documentation/sound/alsa/alsa-parameters.txt
296
Russell Kingd944d542010-02-20 16:13:29 +0000297 alignment= [KNL,ARM]
298 Allow the default userspace alignment fault handler
299 behaviour to be specified. Bit 0 enables warnings,
300 bit 1 enables fixups, and bit 2 sends a segfault.
301
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 Machek71f770552008-07-04 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
Len Brown62027ae2011-04-01 18:13:10 -0400549 cpuidle.off=1 [CPU_IDLE]
550 disable the cpuidle sub-system
551
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700553 Format:
554 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800556 crashkernel=size[KMG][@offset[KMG]]
557 [KNL] Using kexec, Linux can switch to a 'crash kernel'
558 upon panic. This parameter reserves the physical
559 memory region [offset, offset + size] for that kernel
560 image. If '@offset' is omitted, then a suitable offset
561 is selected automatically. Check
562 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700563
Bernhard Wallefb391592007-10-18 23:41:02 -0700564 crashkernel=range1:size1[,range2:size2,...][@offset]
565 [KNL] Same as above, but depends on the memory
566 in the running system. The syntax of range is
567 start-[end] where start and end are both
568 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800569 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 cs89x0_dma= [HW,NET]
572 Format: <dma>
573
574 cs89x0_media= [HW,NET]
575 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700576
Randy Dunlapa9913042005-10-23 12:57:11 -0700577 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 See header of drivers/s390/block/dasd_devmap.c.
579
580 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
581 (one device per port)
582 Format: <port#>,<type>
583 See also Documentation/input/joystick-parport.txt
584
Thomas Renningera648ec02010-08-06 16:11:02 +0200585 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
586 time. See Documentation/dynamic-debug-howto.txt for
587 details.
588
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 debug [KNL] Enable kernel debugging (events log level).
590
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700591 debug_locks_verbose=
592 [KNL] verbose self-tests
593 Format=<0|1>
594 Print debugging info while doing the locking API
595 self-tests.
596 We default to 0 (no extra messages), setting it to
597 1 will print _a lot_ more information - normally
598 only useful to kernel developers.
599
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700600 debug_objects [KNL] Enable object debugging
601
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500602 no_debug_objects
603 [KNL] Disable object debugging
604
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200605 debugpat [X86] Enable PAT debugging
606
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200607 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 Format: <area>[,<node>]
609 See also Documentation/networking/decnet.txt.
610
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700611 default_hugepagesz=
612 [same as hugepagesz=] The size of the default
613 HugeTLB page size. This is the size represented by
614 the legacy /proc/ hugepages APIs, used for SHM, and
615 default size when mounting hugetlbfs filesystems.
616 Defaults to the default architecture's huge page size
617 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700618
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 dhash_entries= [KNL]
620 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 digi= [HW,SERIAL]
623 IO parameters + enable/disable command.
624
625 digiepca= [HW,SERIAL]
626 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000627 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628
Brian Haleyb0f83b22010-02-04 13:36:50 -0800629 disable= [IPV6]
630 See Documentation/networking/ipv6.txt.
631
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000632 disable_ddw [PPC/PSERIES]
633 Disable Dynamic DMA Window support. Use this if
634 to workaround buggy firmware.
635
Brian Haleyb0f83b22010-02-04 13:36:50 -0800636 disable_ipv6= [IPV6]
637 See Documentation/networking/ipv6.txt.
638
Yinghai Lu95ffa242008-04-29 03:52:33 -0700639 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700640 The kernel tries to adjust MTRR layout from continuous
641 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700642 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700643
Yinghai Lu093af8d2008-01-30 13:33:32 +0100644 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100645 By default the kernel will trim any uncacheable
646 memory out of your available memory pool based on
647 MTRR settings. This parameter disables that behavior,
648 possibly causing your machine to run very slowly.
649
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530650 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700651 Disable PIN 1 of APIC timer
652 Can be useful to work around chipset bugs.
653
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
655 this option disables the debugging code at boot.
656
657 dma_debug_entries=<number>
658 This option allows to tune the number of preallocated
659 entries for DMA-API debugging code. One entry is
660 required per DMA-API allocation. Use this if the
661 DMA-API debugging code disables itself because the
662 architectural default is too low.
663
Joerg Roedel1745de52009-05-22 21:49:51 +0200664 dma_debug_driver=<driver_name>
665 With this option the DMA-API debugging driver
666 filter feature can be enabled at boot time. Just
667 pass the driver to filter for as the parameter.
668 The filter can be disabled or changed to another
669 driver later using sysfs.
670
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 dscc4.setup= [NET]
672
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700673 earlycon= [KNL] Output early console device and options.
674 uart[8250],io,<addr>[,options]
675 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700676 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700677 Start an early, polled-mode console on the 8250/16550
678 UART at the specified I/O port or MMIO address.
Samium Gromoff1917ac72010-07-20 15:26:51 -0700679 MMIO inter-register address stride is either 8bit (mmio)
680 or 32bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700681 The options are the same as for ttyS, above.
682
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530683 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 earlyprintk=vga
685 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500686 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500687 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688
Randy Dunlapa9913042005-10-23 12:57:11 -0700689 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 takes over.
691
Yinghai Lu5c059172008-07-24 17:29:40 -0700692 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693
694 Currently only ttyS0 and ttyS1 are supported.
695
696 Interaction with the standard serial driver is not
697 very good.
698
699 The VGA output is eventually overwritten by the real
700 console.
701
Jason Wessel97311912010-05-20 21:04:30 -0500702 ekgdboc= [X86,KGDB] Allow early kernel console debugging
703 ekgdboc=kbd
704
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300705 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500706 the boot argument: earlyprintk=vga
707
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700709 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 eisa_irq_edge= [PARISC,HW]
712 See header of drivers/parisc/eisa.c.
713
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700714 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 See comment before function elanfreq_setup() in
Pavel Machek71f770552008-07-04 09:59:43 -0700716 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717
718 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100719 Format: {"cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700720 See Documentation/block/as-iosched.txt and
721 Documentation/block/deadline-iosched.txt for details.
722
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530723 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700724 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800725 image elf header. Generally kexec loader will
726 pass this option to capture kernel.
727 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700729 enable_mtrr_cleanup [X86]
730 The kernel tries to adjust MTRR layout from continuous
731 to discrete, to make X server driver able to add WB
732 entry later. This parameter enables that.
733
Randy Dunlapca1eda22009-05-06 16:02:58 -0700734 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700735 Enable PIN 1 of APIC timer
736 Can be useful to work around chipset bugs
737 (in particular on some ATI chipsets).
738 The kernel tries to set a reasonable default.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 enforcing [SELINUX] Set initial enforcing status.
741 Format: {"0" | "1"}
742 See security/selinux/Kconfig help text.
743 0 -- permissive (log only, no denials).
744 1 -- enforcing (deny and log).
745 Default value is 0.
746 Value can be changed at runtime via /selinux/enforce.
747
Huang Yinga08f82d2010-05-18 14:35:21 +0800748 erst_disable [ACPI]
749 Disable Error Record Serialization Table (ERST)
750 support.
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 ether= [HW,NET] Ethernet cards parameters
753 This option is obsoleted by the "netdev=" option, which
754 has equivalent usage. See its documentation for details.
755
Akinobu Mitade1ba092006-12-08 02:39:42 -0800756 failslab=
757 fail_page_alloc=
758 fail_make_request=[KNL]
759 General fault injection mechanism.
760 Format: <interval>,<probability>,<space>,<times>
761 See also /Documentation/fault-injection/.
762
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000764 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765
Alex Chiangf13ae302008-05-08 14:03:23 -0600766 force_pal_cache_flush
767 [IA-64] Avoid check_sal_cache_flush which may hang on
768 buggy SAL_CACHE_FLUSH implementations. Using this
769 parameter will force ia64_sal_cache_flush to call
770 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
771
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100772 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400773 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100774 as early as possible in order to facilitate early
775 boot debugging.
776
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200777 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400778 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200779 If no parameter is passed, ftrace will dump
780 buffers of all CPUs, but if you pass orig_cpu, it will
781 dump only the buffer of the CPU that triggered the
782 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400783
784 ftrace_filter=[function-list]
785 [FTRACE] Limit the functions traced by the function
786 tracer at boot up. function-list is a comma separated
787 list of functions. This list can be changed at run
788 time by the set_ftrace_filter file in the debugfs
789 tracing directory.
790
791 ftrace_notrace=[function-list]
792 [FTRACE] Do not trace the functions specified in
793 function-list. This list can be changed at run time
794 by the set_ftrace_notrace file in the debugfs
795 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100796
Stefan Assmann369bc182009-10-12 22:17:21 +0200797 ftrace_graph_filter=[function-list]
798 [FTRACE] Limit the top level callers functions traced
799 by the function graph tracer at boot up.
800 function-list is a comma separated list of functions
801 that can be changed at run time by the
802 set_graph_function file in the debugfs tracing directory.
803
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 gamecon.map[2|3]=
805 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
806 support via parallel port (up to 5 devices per port)
807 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
808 See also Documentation/input/joystick-parport.txt
809
810 gamma= [HW,DRM]
811
Yinghai Luaaf23042008-01-30 13:33:09 +0100812 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
813 Format: off | on
814 default: on
815
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700816 gcov_persist= [GCOV] When non-zero (default), profiling data for
817 kernel modules is saved and remains accessible via
818 debugfs, even when the module is unloaded/reloaded.
819 When zero, profiling data is discarded and associated
820 debugfs files are removed at module unload time.
821
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 gpt [EFI] Forces disk with valid GPT signature but
823 invalid Protective MBR to be treated as GPT.
824
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 hashdist= [KNL,NUMA] Large hashes allocated during boot
826 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700827 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700828 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829
830 hcl= [IA-64] SGI's Hardware Graph compatibility layer
831
832 hd= [EIDE] (E)IDE hard drive subsystem geometry
833 Format: <cyl>,<head>,<sect>
834
Huang Yingea8c0712010-05-18 14:35:15 +0800835 hest_disable [ACPI]
836 Disable Hardware Error Source Table (HEST) support;
837 corresponding firmware-first mode error processing
838 logic will be disabled.
839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
841 size of <nn>. This works even on boxes that have no
842 highmem otherwise. This also works to reduce highmem
843 size on bigger boxes.
844
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800845 highres= [KNL] Enable/disable high resolution timer mode.
846 Valid parameters: "on", "off"
847 Default: "on"
848
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 hisax= [HW,ISDN]
850 See Documentation/isdn/README.HiSax.
851
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700852 hlt [BUGS=ARM,SH]
853
854 hpet= [X86-32,HPET] option to control HPET usage
855 Format: { enable (default) | disable | force |
856 verbose }
857 disable: disable HPET and use PIT instead
858 force: allow force enabled of undocumented chips (ICH4,
859 VIA, nVidia)
860 verbose: show contents of HPET registers during setup
861
Andi Kleenb4718e62008-07-23 21:27:51 -0700862 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
863 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700864 On x86-64 and powerpc, this option can be specified
865 multiple times interleaved with hugepages= to reserve
866 huge pages of different sizes. Valid pages sizes on
867 x86-64 are 2M (when the CPU supports "pse") and 1G
868 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700869 Note that 1GB pages can only be allocated at boot time
870 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900871
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100872 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
873 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100874 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
875 If specified, z/VM IUCV HVC accepts connections
876 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100877
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700878 keep_bootcon [KNL]
879 Do not unregister boot console at start. This is only
880 useful for debugging when something happens in the window
881 between unregistering the boot console and initializing
882 the real console.
883
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700884 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700885 or register an additional I2C bus that is not
886 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700887 Format:
888 <bus_id>,<clkrate>
889
Jiri Kosina36d95732008-10-06 02:51:09 -0400890 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200892 i8042.dumbkbd [HW] Pretend that controller can only read data from
893 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 (Don't attempt to blink the leds)
895 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500896 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400897 i8042.noloop [HW] Disable the AUX Loopback command while probing
898 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 i8042.nomux [HW] Don't check presence of an active multiplexing
900 controller
901 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
902 controllers
Jiri Kosinaf8313ef2011-01-08 01:37:26 -0800903 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 i8042.reset [HW] Reset the controller during init and cleanup
905 i8042.unlock [HW] Unlock (ignore) the keylock
906
907 i810= [HW,DRM]
908
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700909 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
910 indicates that the driver is running on unsupported
911 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
913 does not match list of supported models.
914 i8k.power_status
915 [HW] Report power status in /proc/i8k
916 (disabled by default)
917 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
918 capability is set.
919
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 icn= [HW,ISDN]
921 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
922
David Fries0af80c02009-02-25 20:28:21 +0100923 ide-core.nodma= [HW] (E)IDE subsystem
924 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200925 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
926 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100927 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700929 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
930 Claim all unknown PCI IDE storage controllers.
931
Andi Kleenf039b752007-05-02 19:27:12 +0200932 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800933 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
934 Poll forces a polling idle loop that can slightly
935 improve the performance of waking up a idle CPU, but
936 will use a lot of power and make the system run hot.
937 Not recommended.
938 idle=mwait: On systems which support MONITOR/MWAIT but
939 the kernel chose to not use it because it doesn't save
940 as much power as a normal idle loop, use the
941 MONITOR/MWAIT idle loop anyways. Performance should be
942 the same as idle=poll.
943 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800944 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800945 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700946
Ingo Molnar792908222006-12-06 20:40:51 -0800947 ignore_loglevel [KNL]
948 Ignore loglevel setting - this will print /all/
949 kernel messages to the console. Useful for debugging.
950
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 ihash_entries= [KNL]
952 Set number of hash buckets for inode cache.
953
Mimi Zohar3323eec2009-02-04 09:06:58 -0500954 ima_audit= [IMA]
955 Format: { "0" | "1" }
956 0 -- integrity auditing messages. (Default)
957 1 -- enable informational integrity auditing messages.
958
959 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700960 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500961 default: "sha1"
962
Eric Paris5789ba32009-05-21 15:47:06 -0400963 ima_tcb [IMA]
964 Load a policy which meets the needs of the Trusted
965 Computing Base. This means IMA will measure all
966 programs exec'd, files mmap'd for exec, and all files
967 opened for read by uid=0.
968
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 init= [KNL]
970 Format: <full_path>
971 Run specified binary instead of /sbin/init as init
972 process.
973
974 initcall_debug [KNL] Trace initcalls as they are executed. Useful
975 for working out where the kernel is dying during
976 startup.
977
978 initrd= [BOOT] Specify the location of the initial ramdisk
979
980 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
981 Format: <irq>
982
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700983 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800984 on
985 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700986 off
987 Disable intel iommu driver.
988 igfx_off [Default Off]
989 By default, gfx is mapped as normal device. If a gfx
990 device has a dedicated DMAR unit, the DMAR unit is
991 bypassed by not enabling DMAR with this option. In
992 this case, gfx device will use physical address for
993 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700994 forcedac [x86_64]
995 With this option iommu will not optimize to look
996 for io virtual address below 32 bit forcing dual
997 address cycle on pci bus for cards supporting greater
998 than 32 bit addressing. The default is to look
999 for translation below 32 bit and if not available
1000 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001001 strict [Default Off]
1002 With this option on every unmap_single operation will
1003 result in a hardware IOTLB flush operation as opposed
1004 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001005 sp_off [Default Off]
1006 By default, super page will be supported if Intel IOMMU
1007 has the capability. With this option, super page will
1008 not be supported.
Chris Wrightd1423d52010-07-20 11:06:49 -07001009 intremap= [X86-64, Intel-IOMMU]
1010 Format: { on (default) | off | nosid }
1011 on enable Interrupt Remapping (default)
1012 off disable Interrupt Remapping
1013 nosid disable Source ID checking
1014
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001015 inttest= [IA64]
1016
1017 iomem= Disable strict checking of access to MMIO memory
1018 strict regions from userspace.
1019 relaxed
1020
1021 iommu= [x86]
1022 off
1023 force
1024 noforce
1025 biomerge
1026 panic
1027 nopanic
1028 merge
1029 nomerge
1030 forcesac
1031 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001032 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001033
1034 io7= [HW] IO7 for Marvel based alpha systems
1035 See comment before marvel_specify_io7 in
1036 arch/alpha/kernel/core_marvel.c.
1037
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301038 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001039 0x80
1040 Standard port 0x80 based delay
1041 0xed
1042 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001043 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001044 Simple two microseconds delay
1045 none
1046 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001047
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001049 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
1051 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001052 See comment before ip2_setup() in
1053 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054
Alan Cox200803d2005-06-28 20:45:18 -07001055 irqfixup [HW]
1056 When an interrupt is not handled search all handlers
1057 for it. Intended to get systems with badly broken
1058 firmware running.
1059
1060 irqpoll [HW]
1061 When an interrupt is not handled search all handlers
1062 for it. Also check all handlers each timer
1063 interrupt. Intended to get systems with badly broken
1064 firmware running.
1065
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001067 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068
1069 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001070 Format:
1071 <cpu number>,...,<cpu number>
1072 or
Li Zefanb225d442008-11-06 12:53:39 -08001073 <cpu number>-<cpu number>
1074 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001075 or a mixture
1076 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001077
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 This option can be used to specify one or more CPUs
1079 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001080 algorithms. You can move a process onto or off an
1081 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 <cpu number> begins at 0 and the maximum value is
1083 "number of CPUs in system - 1".
1084
1085 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001086 alternative -- manually setting the CPU mask of all
1087 tasks in the system -- can cause problems and
1088 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089
Randy Dunlapa9913042005-10-23 12:57:11 -07001090 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091
1092 js= [HW,JOY] Analog joystick
1093 See Documentation/input/joystick.txt.
1094
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001095 keepinitrd [HW,ARM]
1096
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301097 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001098 specifies the amount of memory usable by the kernel
1099 for non-movable allocations. The requested amount is
1100 spread evenly throughout all nodes in the system. The
1101 remaining memory in each node is used for Movable
1102 pages. In the event, a node is too small to have both
1103 kernelcore and Movable pages, kernelcore pages will
1104 take priority and other nodes will have a larger number
1105 of kernelcore pages. The Movable zone is used for the
1106 allocation of pages that may be reclaimed or moved
1107 by the page migration subsystem. This means that
1108 HugeTLB pages may not be allocated from this zone.
1109 Note that allocations like PTEs-from-HighMem still
1110 use the HighMem zone if it exists, and the Normal
1111 zone if it does not.
1112
Jason Wessel4fe1da42010-05-20 21:04:31 -05001113 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1114 Format: <Controller#>[,poll interval]
1115 The controller # is the number of the ehci usb debug
1116 port as it is probed via PCI. The poll interval is
1117 optional and is the number seconds in between
1118 each poll cycle to the debug port in case you need
1119 the functionality for interrupting the kernel with
1120 gdb or control-c on the dbgp connection. When
1121 not using this parameter you use sysrq-g to break into
1122 the kernel debugger.
1123
Jason Wessel84c08fd2010-05-20 21:04:24 -05001124 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001125 Requires a tty driver that supports console polling,
1126 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001127 Serial only format: <serial_device>[,baud]
1128 keyboard only format: kbd
1129 keyboard and serial format: kbd,<serial_device>[,baud]
1130 Optional Kernel mode setting:
1131 kms, kbd format: kms,kbd
1132 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001133
Jason Wessel84c08fd2010-05-20 21:04:24 -05001134 kgdbwait [KGDB] Stop kernel execution and enter the
1135 kernel debugger at the earliest opportunity.
1136
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001137 kmac= [MIPS] korina ethernet MAC address.
1138 Configure the RouterBoard 532 series on-chip
1139 Ethernet adapter MAC address.
1140
Catalin Marinas04f70332009-06-11 13:22:39 +01001141 kmemleak= [KNL] Boot-time kmemleak enable/disable
1142 Valid arguments: on, off
1143 Default: on
1144
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301145 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001146 in oops dumps.
1147
Andre Przywarafef07aa2009-07-10 14:20:35 +02001148 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1149 Default is 0 (don't ignore, but inject #GP)
1150
1151 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1152 Default is 1 (enabled)
1153
Xiao Guangronga182d872010-09-20 22:17:48 +08001154 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1155 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001156 Default is 0 (off)
1157
Andre Przywarafef07aa2009-07-10 14:20:35 +02001158 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001159 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001160
1161 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1162 for all guests.
1163 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1164
1165 kvm-intel.bypass_guest_pf=
1166 [KVM,Intel] Disables bypassing of guest page faults
1167 on Intel chips. Default is 1 (enabled)
1168
1169 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1170 (virtualized MMU) support on capable Intel chips.
1171 Default is 1 (enabled)
1172
1173 kvm-intel.emulate_invalid_guest_state=
1174 [KVM,Intel] Enable emulation of invalid guest states
1175 Default is 0 (disabled)
1176
1177 kvm-intel.flexpriority=
1178 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1179 Default is 1 (enabled)
1180
1181 kvm-intel.unrestricted_guest=
1182 [KVM,Intel] Disable unrestricted guest feature
1183 (virtualized real and unpaged mode) on capable
1184 Intel chips. Default is 1 (enabled)
1185
1186 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1187 feature (tagged TLBs) on capable Intel chips.
1188 Default is 1 (enabled)
1189
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 l2cr= [PPC]
1191
Robert Brosea78bfbf2008-03-29 07:20:23 +11001192 l3cr= [PPC]
1193
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001194 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001195 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301197 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001198 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001199
FD Camifcb71f62008-01-06 19:08:56 +01001200 libata.dma= [LIBATA] DMA control
1201 libata.dma=0 Disable all PATA and SATA DMA
1202 libata.dma=1 PATA and SATA Disk DMA only
1203 libata.dma=2 ATAPI (CDROM) DMA only
1204 libata.dma=4 Compact Flash DMA only
1205 Combinations also work, so libata.dma=3 enables DMA
1206 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001207
1208 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1209 libata.ignore_hpa=0 keep BIOS limits (default)
1210 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001211
Dave Jones78e70c22007-09-27 11:50:13 -04001212 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1213 when set.
1214 Format: <int>
1215
Tejun Heo33267322008-02-13 09:15:09 +09001216 libata.force= [LIBATA] Force configurations. The format is comma
1217 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001218 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001219 matching port, link or device. Basically, it matches
1220 the ATA ID string printed on console by libata. If
1221 the whole ID part is omitted, the last PORT and DEVICE
1222 values are used. If ID hasn't been specified yet, the
1223 configuration applies to all ports, links and devices.
1224
1225 If only DEVICE is omitted, the parameter applies to
1226 the port and all links and devices behind it. DEVICE
1227 number of 0 either selects the first device or the
1228 first fan-out link behind PMP device. It does not
1229 select the host link. DEVICE number of 15 selects the
1230 host link and device attached to it.
1231
1232 The VAL specifies the configuration to force. As long
1233 as there's no ambiguity shortcut notation is allowed.
1234 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1235 The following configurations can be forced.
1236
1237 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1238 Any ID with matching PORT is used.
1239
1240 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1241
1242 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1243 udma[/][16,25,33,44,66,100,133] notation is also
1244 allowed.
1245
1246 * [no]ncq: Turn on or off NCQ.
1247
Tejun Heo05944bd2008-08-13 20:19:09 +09001248 * nohrst, nosrst, norst: suppress hard, soft
1249 and both resets.
1250
Tejun Heo43c9c592010-05-23 12:59:11 +02001251 * dump_id: dump IDENTIFY data.
1252
Tejun Heo33267322008-02-13 09:15:09 +09001253 If there are multiple matching configurations changing
1254 the same attribute, the last one is used.
1255
Yinghai Lu95f72d12010-07-12 14:36:09 +10001256 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001257
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001259 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001261 lockd.nlm_grace_period=P [NFS] Assign grace period.
1262 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001264 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1265 Format: <integer>
1266
1267 lockd.nlm_timeout=T [NFS] Assign timeout value.
1268 Format: <integer>
1269
1270 lockd.nlm_udpport=M [NFS] Assign UDP port.
1271 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
1273 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1274 Format: <irq>
1275
1276 loglevel= All Kernel Messages with a loglevel smaller than the
1277 console loglevel will be printed to the console. It can
1278 also be changed with klogd or other programs. The
1279 loglevels are defined as follows:
1280
1281 0 (KERN_EMERG) system is unusable
1282 1 (KERN_ALERT) action must be taken immediately
1283 2 (KERN_CRIT) critical conditions
1284 3 (KERN_ERR) error conditions
1285 4 (KERN_WARNING) warning conditions
1286 5 (KERN_NOTICE) normal but significant condition
1287 6 (KERN_INFO) informational
1288 7 (KERN_DEBUG) debug-level messages
1289
Randy Dunlapc756d082011-02-20 20:08:35 -08001290 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1291 in bytes. n must be a power of two. The default
1292 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
Randy Dunlapaccaa242007-10-16 01:29:37 -07001294 logo.nologo [FB] Disables display of the built-in Linux logo.
1295 This may be used to provide more screen space for
1296 kernel log messages and is useful when debugging
1297 kernel boot problems.
1298
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 lp=0 [LP] Specify parallel ports to use, e.g,
1300 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1301 lp=reset first parallel port). 'lp=0' disables the
1302 lp=auto printer driver. 'lp=reset' (which can be
1303 specified in addition to the ports) causes
1304 attached printers to be reset. Using
1305 lp=port1,port2,... specifies the parallel ports
1306 to associate lp devices with, starting with
1307 lp0. A port specification may be 'none' to skip
1308 that lp device, or a parport name such as
1309 'parport0'. Specifying 'lp=auto' instead of a
1310 port specification list means that device IDs
1311 from each port should be examined, to see if
1312 an IEEE 1284-compliant printer is attached; if
1313 so, the driver will manage that printer.
1314 See also header of drivers/char/lp.c.
1315
1316 lpj=n [KNL]
1317 Sets loops_per_jiffy to given constant, thus avoiding
1318 time-consuming boot-time autodetection (up to 250 ms per
1319 CPU). 0 enables autodetection (default). To determine
1320 the correct value for your kernel, boot with normal
1321 autodetection and see what value is printed. Note that
1322 on SMP systems the preset will be applied to all CPUs,
1323 which is likely to cause problems if your CPUs need
1324 significantly divergent settings. An incorrect value
1325 will cause delays in the kernel to be wrong, leading to
1326 unpredictable I/O errors and other breakage. Although
1327 unlikely, in the extreme case this might damage your
1328 hardware.
1329
1330 ltpc= [NET]
1331 Format: <io>,<irq>,<dma>
1332
Randy Dunlapa9913042005-10-23 12:57:11 -07001333 machvec= [IA64] Force the use of a particular machine-vector
1334 (machvec) in a generic kernel.
1335 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336
Wu Zhangjin3209e702009-07-02 23:27:12 +08001337 machtype= [Loongson] Share the same kernel image file between different
1338 yeeloong laptop.
1339 Example: machtype=lemote-yeeloong-2f-7inch
1340
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001341 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1342 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343
1344 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001345 should make use of. maxcpus=n : n >= 0 limits the
1346 kernel to using 'n' processors. n=0 is a special case,
1347 it is equivalent to "nosmp", which also disables
1348 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001350 max_loop= [LOOP] Maximum number of loopback devices that can
1351 be mounted
1352 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001353
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 mcatest= [IA-64]
1355
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001356 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357
Uwe Hermann71cced62008-10-20 09:32:21 -07001358 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001359
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 md= [HW] RAID subsystems devices and level
1361 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001362
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 mdacon= [MDA]
1364 Format: <first>,<last>
1365 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1368 Amount of memory to be used when the kernel is not able
1369 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001370 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 address space collisions. Without memmap= PCI devices
1372 could be placed at addresses belonging to unused RAM.
1373
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001374 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 memory.
1376
Paul Mundt6902aa82008-09-21 17:14:42 +09001377 memchunk=nn[KMG]
1378 [KNL,SH] Allow user to override the default size for
1379 per-device physically contiguous DMA buffers.
1380
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301381 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 E820 memory map, as specified by the user.
1383 Such memmap=exactmap lines can be constructed based on
1384 BIOS output or other requirements. See the memmap=nn@ss
1385 option description.
1386
1387 memmap=nn[KMG]@ss[KMG]
1388 [KNL] Force usage of a specific region of memory
1389 Region of memory to be used, from ss to ss+nn.
1390
1391 memmap=nn[KMG]#ss[KMG]
1392 [KNL,ACPI] Mark specific memory as ACPI data.
1393 Region of memory to be used, from ss to ss+nn.
1394
1395 memmap=nn[KMG]$ss[KMG]
1396 [KNL,ACPI] Mark specific memory as reserved.
1397 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001398 Example: Exclude memory from 0x18690000-0x1869ffff
1399 memmap=64K$0x18690000
1400 or
1401 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001403 memory_corruption_check=0/1 [X86]
1404 Some BIOSes seem to corrupt the first 64k of
1405 memory when doing things like suspend/resume.
1406 Setting this option will scan the memory
1407 looking for corruption. Enabling this will
1408 both detect corruption and prevent the kernel
1409 from using the memory being corrupted.
1410 However, its intended as a diagnostic tool; if
1411 repeatable BIOS-originated corruption always
1412 affects the same memory, you can use memmap=
1413 to prevent the kernel from using that memory.
1414
1415 memory_corruption_check_size=size [X86]
1416 By default it checks for corruption in the low
1417 64k, making this memory unavailable for normal
1418 use. Use this parameter to scan for
1419 corruption in more or less memory.
1420
1421 memory_corruption_check_period=seconds [X86]
1422 By default it checks for corruption every 60
1423 seconds. Use this parameter to check at some
1424 other rate. 0 disables periodic checking.
1425
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001426 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001427 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001428 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001429 Specifies the number of memtest passes to be
1430 performed. Each pass selects another test
1431 pattern from a given set of patterns. Memtest
1432 fills the memory with this pattern, validates
1433 memory contents and reserves bad memory
1434 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001435
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 meye.*= [HW] Set MotionEye Camera parameters
1437 See Documentation/video4linux/meye.txt.
1438
Andres Salomon8f368812007-10-12 23:04:06 +02001439 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1440 Multi-Function General Purpose Timers on AMD Geode
1441 platforms.
1442
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001443 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1444 the BIOS has incorrectly applied a workaround. TinyBIOS
1445 version 0.98 is known to be affected, 0.99 fixes the
1446 problem by letting the user disable the workaround.
1447
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 mga= [HW,DRM]
1449
Randy Dunlap1c207f92008-11-19 15:36:16 -08001450 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1451 physical address is ignored.
1452
Michel Pollet39f45d72009-05-20 11:10:31 +01001453 mini2440= [ARM,HW,KNL]
1454 Format:[0..2][b][c][t]
1455 Default: "0tb"
1456 MINI2440 configuration specification:
1457 0 - The attached screen is the 3.5" TFT
1458 1 - The attached screen is the 7" TFT
1459 2 - The VGA Shield is attached (1024x768)
1460 Leaving out the screen size parameter will not load
1461 the TFT driver, and the framebuffer will be left
1462 unconfigured.
1463 b - Enable backlight. The TFT backlight pin will be
1464 linked to the kernel VESA blanking code and a GPIO
1465 LED. This parameter is not necessary when using the
1466 VGA shield.
1467 c - Enable the s3c camera interface.
1468 t - Reserved for enabling touchscreen support. The
1469 touchscreen support is not enabled in the mainstream
1470 kernel as of 2.6.30, a preliminary port can be found
1471 in the "bleeding edge" mini2440 support kernel at
1472 http://repo.or.cz/w/linux-2.6/mini2440.git
1473
Mel Gorman6b74ab92008-07-23 21:26:49 -07001474 mminit_loglevel=
1475 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1476 parameter allows control of the logging verbosity for
1477 the additional memory initialisation checks. A value
1478 of 0 disables mminit logging and a level of 4 will
1479 log everything. Information is printed at KERN_DEBUG
1480 so loglevel=8 may also need to be specified.
1481
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482 mousedev.tap_time=
1483 [MOUSE] Maximum time between finger touching and
1484 leaving touchpad surface for touch to be considered
1485 a tap and be reported as a left button click (for
1486 touchpads working in absolute mode only).
1487 Format: <msecs>
1488 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1489 reporting absolute coordinates, such as tablets
1490 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1491 reporting absolute coordinates, such as tablets
1492
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301493 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001494 is similar to kernelcore except it specifies the
1495 amount of memory used for migratable allocations.
1496 If both kernelcore and movablecore is specified,
1497 then kernelcore will be at *least* the specified
1498 value but may be more. If movablecore on its own
1499 is specified, the administrator must be careful
1500 that the amount of memory usable for all allocations
1501 is not too small.
1502
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 MTD_Partition= [MTD]
1504 Format: <name>,<region-number>,<size>,<offset>
1505
Randy Dunlapa9913042005-10-23 12:57:11 -07001506 MTD_Region= [MTD] Format:
1507 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508
1509 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001510 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001512 multitce=off [PPC] This parameter disables the use of the pSeries
1513 firmware feature for updating multiple TCE entries
1514 at a time.
1515
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001516 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1517
1518 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1519
1520 boundary - index of last SLC block on Flex-OneNAND.
1521 The remaining blocks are configured as MLC blocks.
1522 lock - Configure if Flex-OneNAND boundary should be locked.
1523 Once locked, the boundary cannot be changed.
1524 1 indicates lock status, 0 indicates unlock status.
1525
Ben Dooks9db829f2008-07-03 11:24:29 +01001526 mtdset= [ARM]
1527 ARM/S3C2412 JIVE boot control
1528
1529 See arch/arm/mach-s3c2412/mach-jive.c
1530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001532 [HW] Make the MicroTouch USB driver use raw coordinates
1533 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001535 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001536 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001537 that could hold holes aka. UC entries.
1538
1539 mtrr_gran_size=nn[KMG] [X86]
1540 Used for mtrr cleanup. It is granularity of mtrr block.
1541 Default is 1.
1542 Large value could prevent small alignment from
1543 using up MTRRs.
1544
1545 mtrr_spare_reg_nr=n [X86]
1546 Format: <integer>
1547 Range: 0,7 : spare reg number
1548 Default : 1
1549 Used for mtrr cleanup. It is spare mtrr entries number.
1550 Set to 2 or more if your graphical card needs more.
1551
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1553
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 netdev= [NET] Network devices parameters
1555 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1556 Note that mem_start is often overloaded to mean
1557 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001558 This usage is only documented in each driver source
1559 file if at all.
1560
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001561 nf_conntrack.acct=
1562 [NETFILTER] Enable connection tracking flow accounting
1563 0 to disable accounting
1564 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001565 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001566
Chuck Lever306a0752010-09-17 10:54:37 -04001567 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001568 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569
1570 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001571 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572
Chuck Lever306a0752010-09-17 10:54:37 -04001573 nfsrootdebug [NFS] enable nfsroot debugging messages.
1574 See Documentation/filesystems/nfs/nfsroot.txt.
1575
Trond Myklebusta72b4422006-01-03 09:55:41 +01001576 nfs.callback_tcpport=
1577 [NFS] set the TCP port on which the NFSv4 callback
1578 channel should listen.
1579
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001580 nfs.cache_getent=
1581 [NFS] sets the pathname to the program which is used
1582 to update the NFS client cache entries.
1583
1584 nfs.cache_getent_timeout=
1585 [NFS] sets the timeout after which an attempt to
1586 update a cache entry is deemed to have failed.
1587
Trond Myklebust58df0952006-01-03 09:55:57 +01001588 nfs.idmap_cache_timeout=
1589 [NFS] set the maximum lifetime for idmapper cache
1590 entries.
1591
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001592 nfs.enable_ino64=
1593 [NFS] enable 64-bit inode numbers.
1594 If zero, the NFS client will fake up a 32-bit inode
1595 number for the readdir() and stat() syscalls instead
1596 of returning the full 64-bit number.
1597 The default is to return 64-bit inode numbers.
1598
Trond Myklebustb064eca22011-02-22 15:44:32 -08001599 nfs.nfs4_disable_idmapping=
1600 [NFSv4] When set, this option disables the NFSv4
1601 idmapper on the client, but only if the mount
1602 is using the 'sec=sys' security flavour. This may
1603 make migration from legacy NFSv2/v3 systems easier
1604 provided that the server has the appropriate support.
1605 The default is to always enable NFSv4 idmapping.
1606
Paul Mundt1e1030d2009-09-01 17:38:32 +09001607 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001608 when a NMI is triggered.
1609 Format: [state][,regs][,debounce][,die]
1610
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301611 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001612 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001613 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001614 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001615 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001616 timeout occurs (or 'nopanic' to override the opposite
1617 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001618 This is useful when you use a panic=... timeout and
1619 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620
Anton Vorontsovbff38772009-07-08 11:10:56 -07001621 netpoll.carrier_timeout=
1622 [NET] Specifies amount of time (in seconds) that
1623 netpoll should wait for a carrier. By default netpoll
1624 waits 4 seconds.
1625
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001626 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 emulation library even if a 387 maths coprocessor
1628 is present.
1629
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001630 no_console_suspend
1631 [HW] Never suspend the console
1632 Disable suspending of consoles during suspend and
1633 hibernate operations. Once disabled, debugging
1634 messages can reach various consoles while the rest
1635 of the system is being put to sleep (ie, while
1636 debugging driver suspend/resume hooks). This may
1637 not work reliably with all consoles, but is known
1638 to work with serial and VGA consoles.
1639
Christoph Lameterc1aee212007-05-31 00:40:47 -07001640 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1641 caches in the slab allocator. Saves per-node memory,
1642 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001643
Randy Dunlapa9913042005-10-23 12:57:11 -07001644 noalign [KNL,ARM]
1645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 noapic [SMP,APIC] Tells the kernel to not make use of any
1647 IOAPICs that may be present in the system.
1648
Mike Galbraith5091faa2010-11-30 14:18:03 +01001649 noautogroup Disable scheduler automatic task group creation.
1650
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 nobats [PPC] Do not use BATs for mapping kernel lowmem
1652 on "Classic" PPC cores.
1653
1654 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001655
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001656 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1657
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001658 nodelayacct [KNL] Disable per-task delay accounting
1659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1661
Paul Mundt6902aa82008-09-21 17:14:42 +09001662 nodsp [SH] Disable hardware DSP at boot time.
1663
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301664 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001665
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666 noexec [IA-64]
1667
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301668 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001669 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001671 noexec=off: disable non-executable mappings
1672
Fenghua Yude5397a2011-05-11 16:51:05 -07001673 nosmep [X86]
1674 Disable SMEP (Supervisor Mode Execution Protection)
1675 even if it is supported by processor.
1676
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001677 noexec32 [X86-64]
1678 This affects only 32-bit executables.
1679 noexec32=on: enable non-executable mappings (default)
1680 read doesn't imply executable mappings
1681 noexec32=off: disable non-executable mappings
1682 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
Paul Mundt6902aa82008-09-21 17:14:42 +09001684 nofpu [SH] Disable hardware FPU at boot time.
1685
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001686 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001687 register save and restore. The kernel will only save
1688 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689
Suresh Siddha0c752a92009-05-22 12:17:45 -07001690 noxsave [BUGS=X86] Disables x86 extended register state save
1691 and restore using xsave. The kernel will fallback to
1692 enabling legacy floating-point and sse state.
1693
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001694 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1695 wfi(ARM) instruction doesn't work correctly and not to
1696 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001697
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001698 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 instruction doesn't work correctly and not to
1700 use it.
1701
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001702 no_file_caps Tells the kernel not to honor file capabilities. The
1703 only way then for a file to be executed with privilege
1704 is to be setuid root or executed by root.
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 nohalt [IA-64] Tells the kernel not to use the power saving
1707 function PAL_HALT_LIGHT when idle. This increases
1708 power-consumption. On the positive side, it reduces
1709 interrupt wake-up latency, which may improve performance
1710 in certain environments such as networked servers or
1711 real-time systems.
1712
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001713 nohz= [KNL] Boottime enable/disable dynamic ticks
1714 Valid arguments: on, off
1715 Default: on
1716
Paul Mundteeee7852009-04-02 12:31:16 +09001717 noiotrap [SH] Disables trapped I/O port accesses.
1718
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001719 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 disable unhandled interrupt sources.
1721
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301722 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001723 broken timer IRQ sources.
1724
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 noisapnp [ISAPNP] Disables ISA PnP code.
1726
1727 noinitrd [RAM] Tells the kernel not to load any configured
1728 initial RAM disk.
1729
Weidong Han03ea8152009-04-17 16:42:15 +08001730 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1731 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001732 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001733
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734 nointroute [IA-64]
1735
Tony Luck0aa366f2007-07-20 11:22:30 -07001736 nojitter [IA64] Disables jitter checking for ITC timers.
1737
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001738 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1739
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001740 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1741 fault handling.
1742
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001743 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001745 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001746
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 noltlbs [PPC] Do not use large page/tlb entries for kernel
1748 lowmem mapping on PPC40x.
1749
Horms312f1f02006-02-22 09:57:55 +09001750 nomca [IA-64] Disable machine check abort handling
1751
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001752 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001753
Andres Salomon83d73842007-10-12 23:04:06 +02001754 nomfgpt [X86-32] Disable Multi-Function General Purpose
1755 Timer usage (for AMD Geode machines).
1756
Jiri Kosina016ddd92010-01-18 17:05:40 +01001757 nopat [X86] Disable PAT (page attribute table extension of
1758 pagetables) support.
1759
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001760 norandmaps Don't use address space randomization. Equivalent to
1761 echo 0 > /proc/sys/kernel/randomize_va_space
1762
Jiri Kosinabbff2162010-08-11 18:34:09 +02001763 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001764
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001765 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001766 with UP alternatives
1767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 noresidual [PPC] Don't use residual data on PReP machines.
1769
Randy Dunlapa9913042005-10-23 12:57:11 -07001770 noresume [SWSUSP] Disables resume and restores original swap
1771 space.
1772
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 no-scroll [VGA] Disables scrollback.
1774 This is required for the Braillex ib80-piezo Braille
1775 reader made by F.H. Papenmeier (Germany).
1776
1777 nosbagart [IA-64]
1778
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001779 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001780
Len Brown61ec7562007-08-16 03:34:22 -04001781 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1782 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783
Dave Jones97842212007-07-15 23:41:05 -07001784 nosoftlockup [KNL] Disable the soft-lockup detector.
1785
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 nosync [HW,M68K] Disables sync negotiation for all devices.
1787
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001788 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789
1790 nousb [USB] Disable the USB subsystem
1791
Ben Hutchings55142372011-01-02 23:02:42 +00001792 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001793
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001795
Weidong Han2b2fd872009-04-17 16:42:12 +08001796 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1797
Fenghua Yua6c75b862008-03-14 13:57:08 -07001798 nptcg= [IA64] Override max number of concurrent global TLB
1799 purges which is reported from either PAL_VM_SUMMARY or
1800 SAL PALO.
1801
Yinghai Lu2b633e32010-02-10 01:20:37 -08001802 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1803 could support. nr_cpus=n : n >= 1 limits the kernel to
1804 supporting 'n' processors. Later in runtime you can not
1805 use hotplug cpu feature to put more cpu back to online.
1806 just like you compile the kernel NR_CPUS=n
1807
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001808 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1809
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001810 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1811 one of ['zone', 'node', 'default'] can be specified
1812 This can be set from sysctl after boot.
1813 See Documentation/sysctl/vm.txt for details.
1814
Randy Dunlap7c4be252009-01-06 14:42:44 -08001815 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1816 See Documentation/debugging-via-ohci1394.txt for more
1817 info.
1818
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001819 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1820 Rather than timing out after 20 ms if an EC
1821 command is not properly ACKed, override the length
1822 of the timeout. We have interrupts disabled while
1823 waiting for the ACK, so if this is set too high
1824 interrupts *may* be lost!
1825
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001826 omap_mux= [OMAP] Override bootloader pin multiplexing.
1827 Format: <mux_mode0.mode_name=value>...
1828 For example, to override I2C bus2:
1829 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1830
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 oprofile.timer= [HW]
1832 Use timer interrupt instead of performance counters
1833
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001834 oprofile.cpu_type= Force an oprofile cpu type
1835 This might be useful if you have an older oprofile
1836 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001837 Format: { arch_perfmon }
1838 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001839 perfmon on Intel CPUs instead of the
1840 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001841
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001842 oops=panic Always panic on oopses. Default is to just kill the
1843 process, but there is a small probability of
1844 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07001845 This will also cause panics on machine check exceptions.
1846 Useful together with panic=30 to trigger a reboot.
1847
Randy Dunlapbcfde332010-06-07 17:10:38 -07001848 OSS [HW,OSS]
1849 See Documentation/sound/oss/oss-parameters.txt
1850
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001851 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1852 seconds before rebooting
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 Format: <timeout>
1854
1855 parkbd.port= [HW] Parallel port number the keyboard adapter is
1856 connected to, default is 0.
1857 Format: <parport#>
1858 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1859 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001860 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861
Randy Dunlapa9913042005-10-23 12:57:11 -07001862 parport= [HW,PPT] Specify parallel ports. 0 disables.
1863 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1864 Use 'auto' to force the driver to use any
1865 IRQ/DMA settings detected (the default is to
1866 ignore detected IRQ/DMA settings because of
1867 possible conflicts). You can specify the base
1868 address, IRQ, and DMA settings; IRQ and DMA
1869 should be numbers, or 'auto' (for using detected
1870 settings on that particular port), or 'nofifo'
1871 (to avoid using a FIFO even if it is detected).
1872 Parallel ports are assigned in the order they
1873 are specified on the command line, starting
1874 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875
Randy Dunlapa9913042005-10-23 12:57:11 -07001876 parport_init_mode= [HW,PPT]
1877 Configure VIA parallel port to operate in
1878 a specific mode. This is necessary on Pegasos
1879 computer where firmware has no options for setting
1880 up parallel port mode and sets it to spp.
1881 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 Format: [spp|ps2|epp|ecp|ecpepp]
1883
Andrew Mortondd287792006-03-23 03:00:57 -08001884 pause_on_oops=
1885 Halt all CPUs after the first oops has been printed for
1886 the specified number of seconds. This is to be used if
1887 your oopses keep scrolling off the screen.
1888
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 pcbit= [HW,ISDN]
1890
1891 pcd. [PARIDE]
1892 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001893 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894
Randy Dunlapa9913042005-10-23 12:57:11 -07001895 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001896 earlydump [X86] dump PCI config space before the kernel
1897 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001898 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001899 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001900 the hardware directly. Use this if your machine
1901 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001902 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001903 hardware access methods are allowed. Use this
1904 if you experience crashes upon bootup and you
1905 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001906 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001907 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001908 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001909 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001910 noaer [PCIE] If the PCIEAER kernel config parameter is
1911 enabled, this kernel boot option can be used to
1912 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001913 nodomains [PCI] Disable support for multiple PCI
1914 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301915 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001916 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001917 check_enable_amd_mmconf [X86] check for and enable
1918 properly configured MMIO access to PCI
1919 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001920 nomsi [MSI] If the PCI_MSI kernel config parameter is
1921 enabled, this kernel boot option can be used to
1922 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001923 noioapicquirk [APIC] Disable all boot interrupt quirks.
1924 Safety option to keep boot IRQs enabled. This
1925 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001926 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1927 primary IO-APIC for bridges that cannot disable
1928 boot IRQs. This fixes a source of spurious IRQs
1929 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001930 noioapicreroute [APIC] Disable workaround that uses the
1931 boot IRQ equivalent of an IRQ that connects to
1932 a chipset where boot IRQs cannot be disabled.
1933 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001934 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001935 routing table. These calls are known to be buggy
1936 on several machines and they hang the machine
1937 when used, but on other computers it's the only
1938 way to get the interrupt routing table. Try
1939 this option if the kernel is unable to allocate
1940 IRQs or discover secondary PCI buses on your
1941 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001942 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001943 Use with caution as certain devices share
1944 address decoders between ROMs and other
1945 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001946 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001947 expansion ROMs that do not already have
1948 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07001949 nobar [X86] Do not assign address space to the
1950 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001951 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001952 assigned automatically to PCI devices. You can
1953 make the kernel exclude IRQs of your ISA cards
1954 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001955 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001956 of the PIRQ table (normally generated
1957 by the BIOS) if it is outside the
1958 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001959 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001960 useful if the kernel is unable to find your
1961 secondary buses and you want to tell it
1962 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001963 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001964 numbers ourselves, overriding
1965 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001966 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001967 in the BIOS $PIR table. This is needed on
1968 some systems with broken BIOSes, notably
1969 some HP Pavilion N5400 and Omnibook XE3
1970 notebooks. This will have no effect if ACPI
1971 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001972 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001973 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001974 use_crs [X86] Use PCI host bridge window information
1975 from ACPI. On BIOSes from 2008 or later, this
1976 is enabled by default. If you need to use this,
1977 please report a bug.
1978 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1979 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001980 routeirq Do IRQ routing for all PCI devices.
1981 This is normally done in pci_enable_device(),
1982 so this option is a temporary workaround
1983 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001984 skip_isa_align [X86] do not align io start addr, so can
1985 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001986 firmware [ARM] Do not re-enumerate the bus but instead
1987 just use the configuration from the
1988 bootloader. This is currently used on
1989 IXP2000 systems where the bus has to be
1990 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001991 noearly [X86] Don't do any early type 1 scanning.
1992 This might help on some broken boards which
1993 machine check when some devices' config space
1994 is read. But various workarounds are disabled
1995 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001996 bfsort Sort PCI devices into breadth-first order.
1997 This sorting is done to get a device
1998 order compatible with older (<= 2.4) kernels.
1999 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002000 cbiosize=nn[KMG] The fixed amount of bus space which is
2001 reserved for the CardBus bridge's IO window.
2002 The default value is 256 bytes.
2003 cbmemsize=nn[KMG] The fixed amount of bus space which is
2004 reserved for the CardBus bridge's memory
2005 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002006 resource_alignment=
2007 Format:
2008 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2009 Specifies alignment and device to reassign
2010 aligned memory resources.
2011 If <order of align> is not specified,
2012 PAGE_SIZE is used as alignment.
2013 PCI-PCI bridge can be specified, if resource
2014 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002015 ecrc= Enable/disable PCIe ECRC (transaction layer
2016 end-to-end CRC checking).
2017 bios: Use BIOS/firmware settings. This is the
2018 the default.
2019 off: Turn ECRC off
2020 on: Turn ECRC on.
Ram Paif483d392011-07-07 11:19:10 -07002021 realloc reallocate PCI resources if allocations done by BIOS
2022 are erroneous.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002023
Chuck Ebberte5665a42008-09-24 20:40:34 -04002024 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2025 Management.
2026 off Disable ASPM.
2027 force Enable ASPM even on devices that claim not to support it.
2028 WARNING: Forcing ASPM on may cause system lockups.
2029
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002030 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002031 auto Ask the BIOS whether or not to use native PCIe services
2032 associated with PCIe ports (PME, hot-plug, AER). Use
2033 them only if that is allowed by the BIOS.
2034 native Use native PCIe services associated with PCIe ports
2035 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002036 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2037 ports driver.
2038
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002039 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002040 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002041 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002042
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 pcmv= [HW,PCMCIA] BadgePAD 4
2044
2045 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002046 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047
2048 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2049 boot time.
2050 Format: { 0 | 1 }
2051 See arch/parisc/kernel/pdc_chassis.c
2052
Tejun Heof58dc012009-08-14 15:00:50 +09002053 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002054 Currently supported values are "embed" and "page".
2055 Archs may support subset or none of the selections.
2056 See comments in mm/percpu.c for details on each
2057 allocator. This parameter is primarily for debugging
2058 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002059
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002061 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062
2063 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002064 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065
2066 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002067 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068
2069 plip= [PPT,NET] Parallel port network link
2070 Format: { parport<nr> | timid | 0 }
2071 See also Documentation/parport.txt.
2072
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002073 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2074 Override pmtimer IOPort with a hex value.
2075 e.g. pmtmr=0x508
2076
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002077 pnp.debug [PNP]
2078 Enable PNP debug messages. This depends on the
2079 CONFIG_PNP_DEBUG_MESSAGES option.
2080
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 pnpacpi= [ACPI]
2082 { off }
2083
2084 pnpbios= [ISAPNP]
2085 { on | off | curr | res | no-curr | no-res }
2086
2087 pnp_reserve_irq=
2088 [ISAPNP] Exclude IRQs for the autoconfiguration
2089
2090 pnp_reserve_dma=
2091 [ISAPNP] Exclude DMAs for the autoconfiguration
2092
2093 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002094 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095
2096 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002097 [ISAPNP] Exclude memory regions for the
2098 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 Ranges are in pairs (memory base and size).
2100
Randy Dunlap4af94f32009-04-17 18:30:28 -07002101 ports= [IP_VS_FTP] IPVS ftp helper module
2102 Default is 21.
2103 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2104 may be specified.
2105 Format: <port>,<port>....
2106
Ingo Molnar45807a12007-07-15 23:40:10 -07002107 print-fatal-signals=
2108 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002109
2110 If enabled, warn about various signal handling
2111 related application anomalies: too many signals,
2112 too many POSIX.1 timers, fatal signals causing a
2113 coredump - etc.
2114
2115 If you hit the warning due to signal overflow,
2116 you might want to try "ulimit -i unlimited".
2117
Ingo Molnar45807a12007-07-15 23:40:10 -07002118 default: off.
2119
Randy Dunlape84845c2007-07-15 23:40:25 -07002120 printk.time= Show timing data prefixed to each printk message line
2121 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2122
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002123 processor.max_cstate= [HW,ACPI]
2124 Limit processor to maximum C-state
2125 max_cstate=9 overrides any DMI blacklist limit.
2126
2127 processor.nocst [HW,ACPI]
2128 Ignore the _CST method to determine C-states,
2129 instead using the legacy FADT method
2130
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002132 Format: [schedule,]<number>
2133 Param: "schedule" - profile schedule points.
2134 Param: <number> - step/bucket size as a power of 2 for
2135 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002136 Param: "sleep" - profile D-state sleeping (millisecs).
2137 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002138 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2141 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002142 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
Randy Dunlapa9913042005-10-23 12:57:11 -07002144 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2145 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2147 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002148 psmouse.resetafter= [HW,MOUSE]
2149 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 (0 = never).
2151 psmouse.resolution=
2152 [HW,MOUSE] Set desired mouse resolution, in dpi.
2153 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002154 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 0 = disabled, 1 = enabled (default).
2156
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002158 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159
Kay Sieversdc8c8582007-08-15 12:25:38 +02002160 pty.legacy_count=
2161 [KNL] Number of legacy pty's. Overwrites compiled-in
2162 default number.
2163
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002164 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002165
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 r128= [HW,DRM]
2167
2168 raid= [HW,RAID]
2169 See Documentation/md.txt.
2170
Randy Dunlapa9913042005-10-23 12:57:11 -07002171 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002172 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002173
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002175 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002177 rcupdate.blimit= [KNL,BOOT]
2178 Set maximum number of finished RCU callbacks to process
2179 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002180
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002181 rcupdate.qhimark= [KNL,BOOT]
2182 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002183 RCU callbacks over which batch limiting is disabled.
2184
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002185 rcupdate.qlowmark= [KNL,BOOT]
2186 Set threshold of queued RCU callbacks below which
2187 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002188
Olof Johanssonffdfc402005-09-06 15:17:19 -07002189 rdinit= [KNL]
2190 Format: <full_path>
2191 Run specified binary instead of /init from the ramdisk,
2192 used for early userspace startup. See initrd.
2193
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002194 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002196 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197
Paul Jackson46b6d942008-07-04 10:00:09 -07002198 relax_domain_level=
2199 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002200 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002201
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2203
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002204 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002205 Format: nn[KMG]
2206 Reserves a hole at the top of the kernel virtual
2207 address space.
2208
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002209 reservelow= [X86]
2210 Format: nn[K]
2211 Set the amount of memory to reserve for BIOS at
2212 the bottom of the address space.
2213
Vivek Goyal7e962872006-09-27 01:50:44 -07002214 reset_devices [KNL] Force drivers to reset the underlying device
2215 during initialization.
2216
Randy Dunlapa9913042005-10-23 12:57:11 -07002217 resume= [SWSUSP]
2218 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002220 resume_offset= [SWSUSP]
2221 Specify the offset from the beginning of the partition
2222 given by "resume=" at which the swap header is located,
2223 in <PAGE_SIZE> units (needed only for swap files).
2224 See Documentation/power/swsusp-and-swap-files.txt
2225
Bojan Smojverf996fc92010-09-09 23:06:23 +02002226 hibernate= [HIBERNATION]
2227 noresume Don't check if there's a hibernation image
2228 present during boot.
2229 nocompress Don't compress/decompress hibernation images.
2230
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002231 retain_initrd [RAM] Keep initrd memory after extraction
2232
Linus Torvalds1da177e2005-04-16 15:20:36 -07002233 rhash_entries= [KNL,NET]
2234 Set number of hash buckets for route cache
2235
2236 riscom8= [HW,SERIAL]
2237 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2238
2239 ro [KNL] Mount root device read-only on boot
2240
2241 root= [KNL] Root filesystem
2242
2243 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2244 mount the root filesystem
2245
2246 rootflags= [KNL] Set root filesystem mount option string
2247
2248 rootfstype= [KNL] Set root filesystem type
2249
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002250 rootwait [KNL] Wait (indefinitely) for root device to show up.
2251 Useful for devices that are detected asynchronously
2252 (e.g. USB and MMC devices).
2253
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254 rw [KNL] Mount root device read-write on boot
2255
2256 S [KNL] Run init in single mode
2257
2258 sa1100ir [NET]
2259 See drivers/net/irda/sa1100_ir.c.
2260
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002262
Mike Travisf6630112009-11-17 18:22:15 -06002263 sched_debug [KNL] Enables verbose scheduler debug messages.
2264
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002265 security= [SECURITY] Choose a security module to enable at boot.
2266 If this boot parameter is not specified, only the first
2267 security module asking for security registration will be
2268 loaded. An invalid security module name will be treated
2269 as if no module has been chosen.
2270
2271 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 Format: { "0" | "1" }
2273 See security/selinux/Kconfig help text.
2274 0 -- disable.
2275 1 -- enable.
2276 Default value is set via kernel config option.
2277 If enabled at boot time, /selinux/disable can be used
2278 later to disable prior to initial policy load.
2279
John Johansenc1c124e2010-07-29 14:48:09 -07002280 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2281 Format: { "0" | "1" }
2282 See security/apparmor/Kconfig help text
2283 0 -- disable.
2284 1 -- enable.
2285 Default value is set via kernel config option.
2286
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002287 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289 shapers= [NET]
2290 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002291
Yinghai Lub05f78f2008-08-22 01:32:50 -07002292 show_msr= [x86] show boot-time MSR settings
2293 Format: { <integer> }
2294 Show boot-time (BIOS-initialized) MSR settings.
2295 The parameter means the number of CPUs to show,
2296 for example 1 means boot CPU only.
2297
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298 simeth= [IA-64]
2299 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002300
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 slram= [HW,MTD]
2302
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002303 slub_debug[=options[,slabs]] [MM, SLUB]
2304 Enabling slub_debug allows one to determine the
2305 culprit if slab objects become corrupted. Enabling
2306 slub_debug can create guard zones around objects and
2307 may poison objects when not in use. Also tracks the
2308 last alloc / free. For more information see
2309 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002310
2311 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002312 Determines the maximum allowed order for slabs.
2313 A high setting may cause OOMs due to memory
2314 fragmentation. For more information see
2315 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002316
2317 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002318 The minimum number of objects per slab. SLUB will
2319 increase the slab order up to slub_max_order to
2320 generate a sufficiently large slab able to contain
2321 the number of objects indicated. The higher the number
2322 of objects the smaller the overhead of tracking slabs
2323 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002324 For more information see Documentation/vm/slub.txt.
2325
2326 slub_min_order= [MM, SLUB]
2327 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002328 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002329 For more information see Documentation/vm/slub.txt.
2330
2331 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002332 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002333 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002334 allocs to different slabs. Debug options disable
2335 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002336 For more information see Documentation/vm/slub.txt.
2337
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 smart2= [HW]
2339 Format: <io1>[,<io2>[,...,<io8>]]
2340
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002341 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002342 attempt to substitute SMP alternatives once at boot.
2343
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002344 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2345 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2346 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2347 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2348 smsc-ircc2.ircc_irq= [HW] IRQ line
2349 smsc-ircc2.ircc_dma= [HW] DMA channel
2350 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2351 0: Toshiba Satellite 1800 (GP data pin select)
2352 1: Fast pin select (default)
2353 2: ATC IRMode
2354
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002355 softlockup_panic=
2356 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002357 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002358
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2360 See Documentation/sonypi.txt
2361
2362 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002363 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002364
2365 spia_io_base= [HW,MTD]
2366 spia_fio_base=
2367 spia_pedr=
2368 spia_peddr=
2369
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002370 stacktrace [FTRACE]
2371 Enabled the stack tracer on boot up.
2372
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373 sti= [PARISC,HW]
2374 Format: <num>
2375 Set the STI (builtin display/keyboard on the HP-PARISC
2376 machines) console (graphic card) which should be used
2377 as the initial boot-console.
2378 See also comment in drivers/video/console/sticore.c.
2379
2380 sti_font= [HW]
2381 See comment in drivers/video/console/sticore.c.
2382
2383 stifb= [HW]
2384 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2385
Trond Myklebustcbf11072009-08-09 15:06:19 -04002386 sunrpc.min_resvport=
2387 sunrpc.max_resvport=
2388 [NFS,SUNRPC]
2389 SunRPC servers often require that client requests
2390 originate from a privileged port (i.e. a port in the
2391 range 0 < portnr < 1024).
2392 An administrator who wishes to reserve some of these
2393 ports for other uses may adjust the range that the
2394 kernel's sunrpc client considers to be privileged
2395 using these two parameters to set the minimum and
2396 maximum port values.
2397
Greg Banks42a7fc42007-03-06 01:42:23 -08002398 sunrpc.pool_mode=
2399 [NFS]
2400 Control how the NFS server code allocates CPUs to
2401 service thread pools. Depending on how many NICs
2402 you have and where their interrupts are bound, this
2403 option will affect which CPUs will do NFS serving.
2404 Note: this parameter cannot be changed while the
2405 NFS server is running.
2406
2407 auto the server chooses an appropriate mode
2408 automatically using heuristics
2409 global a single global pool contains all CPUs
2410 percpu one pool for each CPU
2411 pernode one pool for each NUMA node (equivalent
2412 to global on non-NUMA machines)
2413
Trond Myklebustcbf11072009-08-09 15:06:19 -04002414 sunrpc.tcp_slot_table_entries=
2415 sunrpc.udp_slot_table_entries=
2416 [NFS,SUNRPC]
2417 Sets the upper limit on the number of simultaneous
2418 RPC calls that can be sent from the client to a
2419 server. Increasing these values may allow you to
2420 improve throughput, but will also increase the
2421 amount of memory reserved for use by the client.
2422
Michal Hockoa42c3902010-11-24 12:57:08 -08002423 swapaccount[=0|1]
2424 [KNL] Enable accounting of swap in memory resource
2425 controller if no parameter or 1 is given or disable
2426 it if 0 is given (See Documentation/cgroups/memory.txt)
2427
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002429
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430 switches= [HW,M68k]
2431
Andi Kleene52eec12010-09-08 16:54:17 +02002432 sysfs.deprecated=0|1 [KNL]
2433 Enable/disable old style sysfs layout for old udev
2434 on older distributions. When this option is enabled
2435 very new udev will not work anymore. When this option
2436 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2437 in older udev will not work anymore.
2438 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2439 the kernel configuration.
2440
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002441 sysrq_always_enabled
2442 [KNL]
2443 Ignore sysrq setting - this boot parameter will
2444 neutralize any effect of /proc/sys/kernel/sysrq.
2445 Useful for debugging.
2446
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447 tdfx= [HW,DRM]
2448
David Brownell77437fd2008-07-23 21:28:33 -07002449 test_suspend= [SUSPEND]
2450 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2451 standby suspend) as the system sleep state to briefly
2452 enter during system startup. The system is woken from
2453 this state using a wakeup-capable RTC alarm.
2454
Linus Torvalds1da177e2005-04-16 15:20:36 -07002455 thash_entries= [KNL,NET]
2456 Set number of hash buckets for TCP connection
2457
Len Brownf8707ec2007-08-12 00:12:54 -04002458 thermal.act= [HW,ACPI]
2459 -1: disable all active trip points in all thermal zones
2460 <degrees C>: override all lowest active trip points
2461
Len Brownc52a7412007-08-14 15:49:32 -04002462 thermal.crt= [HW,ACPI]
2463 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002464 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002465
Len Brownf5487142007-08-12 00:12:44 -04002466 thermal.nocrt= [HW,ACPI]
2467 Set to disable actions on ACPI thermal zone
2468 critical and hot trip points.
2469
Len Brown72b33ef2007-08-12 00:12:17 -04002470 thermal.off= [HW,ACPI]
2471 1: disable ACPI thermal control
2472
Len Browna70cdc52007-08-12 00:12:35 -04002473 thermal.psv= [HW,ACPI]
2474 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002475 <degrees C>: override all passive trip points to this
2476 value
Len Browna70cdc52007-08-12 00:12:35 -04002477
Len Brown730ff342007-08-12 00:12:26 -04002478 thermal.tzp= [HW,ACPI]
2479 Specify global default ACPI thermal zone polling rate
2480 <deci-seconds>: poll all this frequency
2481 0: no polling (default)
2482
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002483 threadirqs [KNL]
2484 Force threading of all interrupt handlers except those
2485 marked explicitely IRQF_NO_THREAD.
2486
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002487 topology= [S390]
2488 Format: {off | on}
2489 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002490 topology information if the hardware supports this.
2491 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002492 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002493 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002494
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495 tp720= [HW,PS2]
2496
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002497 tpm_suspend_pcr=[HW,TPM]
2498 Format: integer pcr id
2499 Specify that at suspend time, the tpm driver
2500 should extend the specified pcr with zeros,
2501 as a workaround for some chips which fail to
2502 flush the last written pcr on TPM_SaveState.
2503 This will guarantee that all the other pcrs
2504 are saved.
2505
Li Zefan9d612be2009-06-24 17:33:15 +08002506 trace_buf_size=nn[KMG]
2507 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002508
Li Zefan020e5f82009-07-01 10:47:05 +08002509 trace_event=[event-list]
2510 [FTRACE] Set and start specified trace events in order
2511 to facilitate early boot debugging.
2512 See also Documentation/trace/events.txt
2513
john stultzd3b8f882009-08-17 16:40:47 -07002514 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002515 Format: <string>
2516 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002517 disables clocksource verification at runtime, as well
2518 as the stability checks done at bootup. Used to enable
2519 high-resolution timer mode on older hardware, and in
2520 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002521 [x86] noirqtime: Do not use TSC to do irq accounting.
2522 Used to run time disable IRQ_TIME_ACCOUNTING on any
2523 platforms where RDTSC is slow and this accounting
2524 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002525
Randy Dunlapa9913042005-10-23 12:57:11 -07002526 turbografx.map[2|3]= [HW,JOY]
2527 TurboGraFX parallel port interface
2528 Format:
2529 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530 See also Documentation/input/joystick-parport.txt
2531
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002532 uhash_entries= [KNL,NET]
2533 Set number of hash buckets for UDP/UDP-Lite connections
2534
Alan Stern5f8364b2006-12-05 16:29:55 -05002535 uhci-hcd.ignore_oc=
2536 [USB] Ignore overcurrent events (default N).
2537 Some badly-designed motherboards generate lots of
2538 bogus events, for ports that aren't wired to
2539 anything. Set this parameter to avoid log spamming.
2540 Note that genuine overcurrent events won't be
2541 reported either.
2542
Simon Arlotte3a61b02008-07-19 23:32:54 +01002543 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002544 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01002545
Alan Sternb5e795f2007-02-20 15:00:53 -05002546 usbcore.autosuspend=
2547 [USB] The autosuspend time delay (in seconds) used
2548 for newly-detected USB devices (default 2). This
2549 is the time required before an idle device will be
2550 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002551 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002552
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002553 usbcore.usbfs_snoop=
2554 [USB] Set to log all usbfs traffic (default 0 = off).
2555
2556 usbcore.blinkenlights=
2557 [USB] Set to cycle leds on hubs (default 0 = off).
2558
2559 usbcore.old_scheme_first=
2560 [USB] Start with the old device initialization
2561 scheme (default 0 = off).
2562
2563 usbcore.use_both_schemes=
2564 [USB] Try the other device initialization scheme
2565 if the first one fails (default 1 = enabled).
2566
2567 usbcore.initial_descriptor_timeout=
2568 [USB] Specifies timeout for the initial 64-byte
2569 USB_REQ_GET_DESCRIPTOR request in milliseconds
2570 (default 5000 = 5.0 seconds).
2571
Linus Torvalds1da177e2005-04-16 15:20:36 -07002572 usbhid.mousepoll=
2573 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002574
Alan Sternd4f373e2008-11-10 14:07:45 -05002575 usb-storage.delay_use=
2576 [UMS] The delay in seconds before a new device is
2577 scanned for Logical Units (default 5).
2578
2579 usb-storage.quirks=
2580 [UMS] A list of quirks entries to supplement or
2581 override the built-in unusual_devs list. List
2582 entries are separated by commas. Each entry has
2583 the form VID:PID:Flags where VID and PID are Vendor
2584 and Product ID values (4-digit hex numbers) and
2585 Flags is a set of characters, each corresponding
2586 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002587 a = SANE_SENSE (collect more than 18 bytes
2588 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002589 b = BAD_SENSE (don't collect more than 18
2590 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002591 c = FIX_CAPACITY (decrease the reported
2592 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01002593 d = NO_READ_DISC_INFO (don't use
2594 READ_DISC_INFO command);
2595 e = NO_READ_CAPACITY_16 (don't use
2596 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05002597 h = CAPACITY_HEURISTICS (decrease the
2598 reported device capacity by one
2599 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002600 i = IGNORE_DEVICE (don't bind to this
2601 device);
2602 l = NOT_LOCKABLE (don't try to lock and
2603 unlock ejectable media);
2604 m = MAX_SECTORS_64 (don't transfer more
2605 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04002606 n = INITIAL_READ10 (force a retry of the
2607 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05002608 o = CAPACITY_OK (accept the capacity
2609 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002610 r = IGNORE_RESIDUE (the device reports
2611 bogus residue values);
2612 s = SINGLE_LUN (the device has only one
2613 Logical Unit);
2614 w = NO_WP_DETECT (don't test whether the
2615 medium is write-protected).
2616 Example: quirks=0419:aaf5:rl,0421:0433:rc
2617
Ian Campbell14315592010-02-17 10:38:10 +00002618 userpte=
2619 [X86] Flags controlling user PTE allocations.
2620
2621 nohigh = do not allocate PTE pages in
2622 HIGHMEM regardless of setting
2623 of CONFIG_HIGHPTE.
2624
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302625 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002626 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002627 vdso=1: enable VDSO (default)
2628 vdso=0: disable VDSO mapping
2629
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302630 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002631 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2632 vdso32=1: enable 32-bit VDSO (default)
2633 vdso32=0: disable 32-bit VDSO mapping
2634
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002635 vector= [IA-64,SMP]
2636 vector=percpu: enable percpu vector domain
2637
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638 video= [FB] Frame buffer configuration
2639 See Documentation/fb/modedb.txt.
2640
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002641 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002642 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002643 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 Use vga=ask for menu.
2645 This is actually a boot loader parameter; the value is
2646 passed to the kernel using a special protocol.
2647
Randy Dunlapa9913042005-10-23 12:57:11 -07002648 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649 size of <nn>. This can be used to increase the
2650 minimum size (128MB on x86). It can also be used to
2651 decrease the size and leave more room for directly
2652 mapped kernel RAM.
2653
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002654 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2655 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002657 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2658 Format: <command>
2659
2660 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2661 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002662
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002663 vt.cur_default= [VT] Default cursor shape.
2664 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2665 the parameters of the <Esc>[?A;B;Cc escape sequence;
2666 see VGA-softcursor.txt. Default: 2 = underline.
2667
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002668 vt.default_blu= [VT]
2669 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2670 Change the default blue palette of the console.
2671 This is a 16-member array composed of values
2672 ranging from 0-255.
2673
2674 vt.default_grn= [VT]
2675 Format: <green0>,<green1>,<green2>,...,<green15>
2676 Change the default green palette of the console.
2677 This is a 16-member array composed of values
2678 ranging from 0-255.
2679
2680 vt.default_red= [VT]
2681 Format: <red0>,<red1>,<red2>,...,<red15>
2682 Change the default red palette of the console.
2683 This is a 16-member array composed of values
2684 ranging from 0-255.
2685
2686 vt.default_utf8=
2687 [VT]
2688 Format=<0|1>
2689 Set system-wide default UTF-8 mode for all tty's.
2690 Default is 1, i.e. UTF-8 mode is enabled for all
2691 newly opened terminals.
2692
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002693 vt.global_cursor_default=
2694 [VT]
2695 Format=<-1|0|1>
2696 Set system-wide default for whether a cursor
2697 is shown on new VTs. Default is -1,
2698 i.e. cursors will be created by default unless
2699 overridden by individual drivers. 0 will hide
2700 cursors, 1 will display them.
2701
Randy Dunlap4724ba52010-05-03 11:42:52 -07002702 watchdog timers [HW,WDT] For information on watchdog timers,
2703 see Documentation/watchdog/watchdog-parameters.txt
2704 or other driver-specific files in the
2705 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002706
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002707 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2708 default x2apic cluster mode on platforms
2709 supporting x2apic.
2710
Jacob Panbb24c472009-09-02 07:37:17 -07002711 x86_mrst_timer= [X86-32,APBT]
2712 Choose timer option for x86 Moorestown MID platform.
2713 Two valid options are apbt timer only and lapic timer
2714 plus one apbt timer for broadcast timer.
2715 x86_mrst_timer=apbt_only | lapic_and_apbt
2716
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2718 xd_geo= See header of drivers/block/xd.c.
2719
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002720 xen_emul_unplug= [HW,X86,XEN]
2721 Unplug Xen emulated devices
2722 Format: [unplug0,][unplug1]
2723 ide-disks -- unplug primary master IDE devices
2724 aux-ide-disks -- unplug non-primary-master IDE devices
2725 nics -- unplug network devices
2726 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002727 unnecessary -- unplugging emulated devices is
2728 unnecessary even if the host did not respond to
2729 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002730 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002731
Linus Torvalds1da177e2005-04-16 15:20:36 -07002732 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002733 Format:
2734 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735
Randy Dunlapa9913042005-10-23 12:57:11 -07002736______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002737
2738TODO:
2739
Linus Torvalds1da177e2005-04-16 15:20:36 -07002740 Add more DRM drivers.