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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050061 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020062 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070063 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070072 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070073 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070076 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070079 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070083 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
93 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070094 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 SELINUX SELinux support is enabled.
96 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090097 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500102 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300103 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500105 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700113 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700116 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119In addition, the following text indicates that the option:
120
121 BUGS= Relates to possible processor bugs on the said processor.
122 KNL Is a kernel start-up parameter.
123 BOOT Is a boot loader parameter.
124
125Parameters denoted with BOOT are actually interpreted by the boot
126loader, and have no meaning to the kernel directly.
127Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500128need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Karsten Weiss55588702007-02-13 13:26:21 +0100130There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700131See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
134a trailing = on the name of any parameter states that that parameter will
135be entered as an environment variable, whereas its absence indicates that
136it will appear as a kernel argument readable via /proc/cmdline by programs
137running once the system is up.
138
jens m. noedler9c4751f2006-09-29 02:00:27 -0700139The number of kernel parameters is not limited, but the length of the
140complete command line (parameters including spaces etc.) is limited to
141a fixed number of characters. This limit depends on the architecture
142and is between 256 and 4096 characters. It is defined in the file
143./include/asm/setup.h as COMMAND_LINE_SIZE.
144
145
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530146 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800147 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500148 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 force -- enable ACPI if default was off
150 off -- disable ACPI if default was on
151 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700152 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800154 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800155 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Randy Dunlap53471122008-03-12 18:10:51 -0400157 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
Len Browna1fdcc02007-03-11 03:26:14 -0400159 acpi_apic_instance= [ACPI, IOAPIC]
160 Format: <int>
161 2: use 2nd APIC table, if available
162 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400163 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400164
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200165 acpi_backlight= [HW,ACPI]
166 acpi_backlight=vendor
167 acpi_backlight=video
168 If set to vendor, prefer vendor specific driver
169 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
170 of the ACPI video.ko driver.
171
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700172 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
173 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700175 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
176 debug output. Bits in debug_layer correspond to a
177 _COMPONENT in an ACPI source file, e.g.,
178 #define _COMPONENT ACPI_PCI_COMPONENT
179 Bits in debug_level correspond to a level in
180 ACPI_DEBUG_PRINT statements, e.g.,
181 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600182 The debug_level mask defaults to "info". See
183 Documentation/acpi/debug.txt for more information about
184 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600186 Enable processor driver info messages:
187 acpi.debug_layer=0x20000000
188 Enable PCI/PCI interrupt routing info messages:
189 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700190 Enable AML "Debug" output, i.e., stores to the Debug
191 object while interpreting AML:
192 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700193 Enable all messages related to ACPI hardware:
194 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200195
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700196 Some values produce so much output that the system is
197 unusable. The "log_buf_len" parameter may be useful
198 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800199
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700200 acpi_display_output= [HW,ACPI]
201 acpi_display_output=vendor
202 acpi_display_output=video
203 See above.
204
205 acpi_irq_balance [HW,ACPI]
206 ACPI will balance active IRQs
207 default in APIC mode
208
209 acpi_irq_nobalance [HW,ACPI]
210 ACPI will not move active IRQs (default)
211 default in PIC mode
212
213 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
214 Format: <irq>,<irq>...
215
216 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
217 use by PCI
218 Format: <irq>,<irq>...
219
220 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
221
222 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
223 Format: To spoof as Windows 98: ="Microsoft Windows"
224
225 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
226 acpi_osi="string1" # add string1 -- only one string
227 acpi_osi="!string2" # remove built-in string2
228 acpi_osi= # disable all strings
229
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530230 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700231 Override the pmtimer bug detection: force the kernel
232 to assume that this machine's pmtimer latches its value
233 and always returns good values.
234
Randy Dunlap4af94f32009-04-17 18:30:28 -0700235 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
236 Format: { level | edge | high | low }
237
238 acpi_serialize [HW,ACPI] force serialization of AML methods
239
240 acpi_skip_timer_override [HW,ACPI]
241 Recognize and ignore IRQ0/pin2 Interrupt Override.
242 For broken nForce2 BIOS resulting in XT-PIC timer.
243
244 acpi_sleep= [HW,ACPI] Sleep options
245 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800246 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700247 See Documentation/power/video.txt for information on
248 s3_bios and s3_mode.
249 s3_beep is for debugging; it makes the PC's speaker beep
250 as soon as the kernel's real-mode entry point is called.
251 s4_nohwsig prevents ACPI hardware signature from being
252 used during resume from hibernation.
253 old_ordering causes the ACPI 1.0 ordering of the _PTS
254 control method, with respect to putting devices into
255 low power states, to be enforced (the ACPI 2.0 ordering
256 of _PTS is used by default).
257 s4_nonvs prevents the kernel from saving/restoring the
258 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800259 sci_force_enable causes the kernel to set SCI_EN directly
260 on resume from S1/S3 (which is against the ACPI spec,
261 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700262
263 acpi_use_timer_override [HW,ACPI]
264 Use timer override. For some broken Nvidia NF5 boards
265 that require a timer override, but don't have HPET
266
Luca Tettamanti7e905602009-03-30 00:01:27 +0200267 acpi_enforce_resources= [ACPI]
268 { strict | lax | no }
269 Check for resource conflicts between native drivers
270 and ACPI OperationRegions (SystemIO and SystemMemory
271 only). IO ports and memory declared in ACPI might be
272 used by the ACPI subsystem in arbitrary AML code and
273 can interfere with legacy drivers.
274 strict (default): access to resources claimed by ACPI
275 is denied; legacy drivers trying to access reserved
276 resources will fail to bind to device using them.
277 lax: access to resources claimed by ACPI is allowed;
278 legacy drivers trying to access reserved resources
279 will bind successfully but a warning message is logged.
280 no: ACPI OperationRegions are not marked as reserved,
281 no further checks are performed.
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 ad1848= [HW,OSS]
284 Format: <io>,<irq>,<dma>,<dma2>,<type>
285
Randy Dunlap4af94f32009-04-17 18:30:28 -0700286 add_efi_memmap [EFI; X86] Include EFI memory map in
287 kernel's map of available physical RAM.
288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 advansys= [HW,SCSI]
290 See header of drivers/scsi/advansys.c.
291
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 aedsp16= [HW,OSS] Audio Excel DSP 16
293 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
294 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700295
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 aha152x= [HW,SCSI]
303 See Documentation/scsi/aha152x.txt.
304
305 aha1542= [HW,SCSI]
306 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
307
308 aic7xxx= [HW,SCSI]
309 See Documentation/scsi/aic7xxx.txt.
310
311 aic79xx= [HW,SCSI]
312 See Documentation/scsi/aic79xx.txt.
313
Russell Kingd944d542010-02-20 16:13:29 +0000314 alignment= [KNL,ARM]
315 Allow the default userspace alignment fault handler
316 behaviour to be specified. Bit 0 enables warnings,
317 bit 1 enables fixups, and bit 2 sends a segfault.
318
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
321 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900322 fullflush - enable flushing of IO/TLB entries when
323 they are unmapped. Otherwise they are
324 flushed before they will be reused, which
325 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200326 off - do not initialize any AMD IOMMU found in
327 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900328
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 amijoy.map= [HW,JOY] Amiga joystick support
330 Map of devices attached to JOY0DAT and JOY1DAT
331 Format: <a>,<b>
332 See also Documentation/kernel/input/joystick.txt
333
334 analog.map= [HW,JOY] Analog joystick and gamepad support
335 Specifies type or capabilities of an analog joystick
336 connected to one of 16 gameports
337 Format: <type1>,<type2>,..<type16>
338
Randy Dunlapa9913042005-10-23 12:57:11 -0700339 apc= [HW,SPARC]
340 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 Format: noidle
342 Disable APC CPU standby support. SPARCstation-Fox does
343 not play well with APC CPU idle - disable it if you have
344 APC and your system crashes randomly.
345
Randy Dunlapca1eda22009-05-06 16:02:58 -0700346 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700347 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 Format: { quiet (default) | verbose | debug }
349 Change the amount of debugging information output
350 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700351
Brian Haleyb0f83b22010-02-04 13:36:50 -0800352 autoconf= [IPV6]
353 See Documentation/networking/ipv6.txt.
354
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400355 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
356 Limit apic dumping. The parameter defines the maximal
357 number of local apics being dumped. Also it is possible
358 to set it to "all" by meaning -- no limit here.
359 Format: { 1 (default) | 2 | ... | all }.
360 The parameter valid if only apic=debug or
361 apic=verbose is specified.
362 Example: apic=debug show_lapic=all
363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700365 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
368 Format: <io>,<irq>,<nodeID>
369
370 ataflop= [HW,M68k]
371
372 atarimouse= [HW,MOUSE] Atari Mouse
373
374 atascsi= [HW,SCSI] Atari SCSI
375
376 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
377 EzKey and similar keyboards
378
379 atkbd.reset= [HW] Reset keyboard during initialization
380
Randy Dunlapa9913042005-10-23 12:57:11 -0700381 atkbd.set= [HW] Select keyboard code set
382 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
384 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
385 keyboards
386
387 atkbd.softraw= [HW] Choose between synthetic and real raw mode
388 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700389
390 atkbd.softrepeat= [HW]
391 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
393 autotest [IA64]
394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 baycom_epp= [HW,AX25]
396 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700397
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
399 Format: <io>,<mode>
400 See header of drivers/net/hamradio/baycom_par.c.
401
Randy Dunlapa9913042005-10-23 12:57:11 -0700402 baycom_ser_fdx= [HW,AX25]
403 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 Format: <io>,<irq>,<mode>[,<baud>]
405 See header of drivers/net/hamradio/baycom_ser_fdx.c.
406
Randy Dunlapa9913042005-10-23 12:57:11 -0700407 baycom_ser_hdx= [HW,AX25]
408 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 Format: <io>,<irq>,<mode>
410 See header of drivers/net/hamradio/baycom_ser_hdx.c.
411
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700412 boot_delay= Milliseconds to delay each printk during boot.
413 Values larger than 10 seconds (10000) are changed to
414 no delay (0).
415 Format: integer
416
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700417 bootmem_debug [KNL] Enable bootmem allocator debug messages.
418
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700420 bttv.radio= Most important insmod options are available as
421 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
423 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
424
425 BusLogic= [HW,SCSI]
426 See drivers/scsi/BusLogic.c, comment before function
427 BusLogic_ParseDriverOptions().
428
429 c101= [NET] Moxa C101 synchronous serial card
430
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700431 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 Sometimes CPU hardware bugs make them report the cache
433 size incorrectly. The kernel will attempt work arounds
434 to fix known problems, but for some CPUs it is not
435 possible to determine what the correct size should be.
436 This option provides an override for these situations.
437
James Morris20510f22007-10-16 23:31:32 -0700438 capability.disable=
439 [SECURITY] Disable capabilities. This would normally
440 be used only if an alternative security model is to be
441 configured. Potentially dangerous and should only be
442 used if you are entirely sure of the consequences.
443
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100444 ccw_timeout_log [S390]
445 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446
Paul Menage8bab8dd2008-04-04 14:29:57 -0700447 cgroup_disable= [KNL] Disable a particular controller
448 Format: {name of the controller(s) to disable}
449 {Currently supported controllers - "memory"}
450
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 checkreqprot [SELINUX] Set initial checkreqprot flag value.
452 Format: { "0" | "1" }
453 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700454 0 -- check protection applied by kernel (includes
455 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 1 -- check protection requested by application.
457 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700458 Value can be changed at runtime via
459 /selinux/checkreqprot.
460
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100461 cio_ignore= [S390]
462 See Documentation/s390/CommonIO for details.
463
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700464 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700465 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200466 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700467 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200468 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 Format: { pit | tsc | cyclone | pmtmr }
470
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700471 clocksource= [GENERIC_TIME] Override the default clocksource
472 Format: <string>
473 Override the default clocksource and use the clocksource
474 with the name specified.
475 Some clocksource names to choose from, depending on
476 the platform:
477 [all] jiffies (this is the base, fallback clocksource)
478 [ACPI] acpi_pm
479 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
480 pxa_timer,timer3,32k_counter,timer0_1
481 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700482 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700483 scx200_hrt on Geode; cyclone on IBM x440
484 [MIPS] MIPS
485 [PARISC] cr16
486 [S390] tod
487 [SH] SuperH
488 [SPARC64] tick
489 [X86-64] hpet,tsc
490
Andi Kleenac72e782008-01-30 13:33:21 +0100491 clearcpuid=BITNUM [X86]
492 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800493 arch/x86/include/asm/cpufeature.h for the valid bit
494 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100495 stable over kernel options, but the vendor specific
496 ones should be.
497 Also note that user programs calling CPUID directly
498 or using the feature without checking anything
499 will still see it. This just prevents it from
500 being used by the kernel or shown in /proc/cpuinfo.
501 Also note the kernel might malfunction if you disable
502 some critical bits.
503
Robert Jennings14f966e2009-04-15 05:55:32 +0000504 cmo_free_hint= [PPC] Format: { yes | no }
505 Specify whether pages are marked as being inactive
506 when they are freed. This is used in CMO environments
507 to determine OS memory pressure for page stealing by
508 a hypervisor.
509 Default: yes
510
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530511 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100512 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100513 Range: 0 - 8192
514 Default: 64
515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700517 Format:
518 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
520 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 Format: <io>[,<irq>]
522
Randy Dunlapa9913042005-10-23 12:57:11 -0700523 com90xx= [HW,NET]
524 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 Format: <io>[,<irq>[,<memstart>]]
526
527 condev= [HW,S390] console device
528 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700529
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 console= [KNL] Output console device and options.
531
532 tty<n> Use the virtual console device <n>.
533
534 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800535 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800537 the form "bbbbpnf", where "bbbb" is the baud rate,
538 "p" is parity ("n", "o", or "e"), "n" is number of
539 bits, and "f" is flow control ("r" for RTS or
540 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800542 See Documentation/serial-console.txt for more
543 information. See
544 Documentation/networking/netconsole.txt for an
545 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700547 uart[8250],io,<addr>[,options]
548 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 Start an early, polled-mode console on the 8250/16550
550 UART at the specified I/O port or MMIO address,
551 switching to the matching ttyS device later. The
552 options are the same as for ttyS, above.
553
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700554 If the device connected to the port is not a TTY but a braille
555 device, prepend "brl," before the device type, for instance
556 console=brl,ttyS0
557 For now, only VisioBraille is supported.
558
Daniel Mackf324edc2009-06-16 15:33:52 -0700559 consoleblank= [KNL] The console blank (screen saver) timeout in
560 seconds. Defaults to 10*60 = 10mins. A value of 0
561 disables the blank timer.
562
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800563 coredump_filter=
564 [KNL] Change the default value for
565 /proc/<pid>/coredump_filter.
566 See also Documentation/filesystems/proc.txt.
567
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700569 Format:
570 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700572 crashkernel=nn[KMG]@ss[KMG]
573 [KNL] Reserve a chunk of physical memory to
574 hold a kernel to switch to with kexec on panic.
575
Bernhard Wallefb391592007-10-18 23:41:02 -0700576 crashkernel=range1:size1[,range2:size2,...][@offset]
577 [KNL] Same as above, but depends on the memory
578 in the running system. The syntax of range is
579 start-[end] where start and end are both
580 a memory unit (amount[KMG]). See also
581 Documentation/kdump/kdump.txt for a example.
582
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 cs89x0_dma= [HW,NET]
584 Format: <dma>
585
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700588
Randy Dunlapa9913042005-10-23 12:57:11 -0700589 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 See header of drivers/s390/block/dasd_devmap.c.
591
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
596
597 debug [KNL] Enable kernel debugging (events log level).
598
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700599 debug_locks_verbose=
600 [KNL] verbose self-tests
601 Format=<0|1>
602 Print debugging info while doing the locking API
603 self-tests.
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
607
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700608 debug_objects [KNL] Enable object debugging
609
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500610 no_debug_objects
611 [KNL] Disable object debugging
612
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200613 debugpat [X86] Enable PAT debugging
614
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200615 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 Format: <area>[,<node>]
617 See also Documentation/networking/decnet.txt.
618
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700619 default_hugepagesz=
620 [same as hugepagesz=] The size of the default
621 HugeTLB page size. This is the size represented by
622 the legacy /proc/ hugepages APIs, used for SHM, and
623 default size when mounting hugetlbfs filesystems.
624 Defaults to the default architecture's huge page size
625 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700626
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 dhash_entries= [KNL]
628 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 digi= [HW,SERIAL]
631 IO parameters + enable/disable command.
632
633 digiepca= [HW,SERIAL]
634 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000635 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
Brian Haleyb0f83b22010-02-04 13:36:50 -0800637 disable= [IPV6]
638 See Documentation/networking/ipv6.txt.
639
640 disable_ipv6= [IPV6]
641 See Documentation/networking/ipv6.txt.
642
Yinghai Lu95ffa242008-04-29 03:52:33 -0700643 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700644 The kernel tries to adjust MTRR layout from continuous
645 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700646 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700647
Yinghai Lu093af8d2008-01-30 13:33:32 +0100648 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100649 By default the kernel will trim any uncacheable
650 memory out of your available memory pool based on
651 MTRR settings. This parameter disables that behavior,
652 possibly causing your machine to run very slowly.
653
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530654 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700655 Disable PIN 1 of APIC timer
656 Can be useful to work around chipset bugs.
657
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 dmasound= [HW,OSS] Sound subsystem buffers
659
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700660 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
661 this option disables the debugging code at boot.
662
663 dma_debug_entries=<number>
664 This option allows to tune the number of preallocated
665 entries for DMA-API debugging code. One entry is
666 required per DMA-API allocation. Use this if the
667 DMA-API debugging code disables itself because the
668 architectural default is too low.
669
Joerg Roedel1745de52009-05-22 21:49:51 +0200670 dma_debug_driver=<driver_name>
671 With this option the DMA-API debugging driver
672 filter feature can be enabled at boot time. Just
673 pass the driver to filter for as the parameter.
674 The filter can be disabled or changed to another
675 driver later using sysfs.
676
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 dscc4.setup= [NET]
678
679 dtc3181e= [HW,SCSI]
680
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700681 dynamic_printk Enables pr_debug()/dev_dbg() calls if
682 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
683 These can also be switched on/off via
684 <debugfs>/dynamic_printk/modules
685
686 earlycon= [KNL] Output early console device and options.
687 uart[8250],io,<addr>[,options]
688 uart[8250],mmio,<addr>[,options]
689 Start an early, polled-mode console on the 8250/16550
690 UART at the specified I/O port or MMIO address.
691 The options are the same as for ttyS, above.
692
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530693 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 earlyprintk=vga
695 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500696 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500697 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
Randy Dunlapa9913042005-10-23 12:57:11 -0700699 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 takes over.
701
Yinghai Lu5c059172008-07-24 17:29:40 -0700702 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703
704 Currently only ttyS0 and ttyS1 are supported.
705
706 Interaction with the standard serial driver is not
707 very good.
708
709 The VGA output is eventually overwritten by the real
710 console.
711
Jason Wessel97311912010-05-20 21:04:30 -0500712 ekgdboc= [X86,KGDB] Allow early kernel console debugging
713 ekgdboc=kbd
714
715 This is desgined to be used in conjunction with
716 the boot argument: earlyprintk=vga
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 eata= [HW,SCSI]
719
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700721 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 eisa_irq_edge= [PARISC,HW]
724 See header of drivers/parisc/eisa.c.
725
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700726 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700728 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729
730 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800731 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700732 See Documentation/block/as-iosched.txt and
733 Documentation/block/deadline-iosched.txt for details.
734
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530735 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700736 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800737 image elf header. Generally kexec loader will
738 pass this option to capture kernel.
739 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700741 enable_mtrr_cleanup [X86]
742 The kernel tries to adjust MTRR layout from continuous
743 to discrete, to make X server driver able to add WB
744 entry later. This parameter enables that.
745
Randy Dunlapca1eda22009-05-06 16:02:58 -0700746 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700747 Enable PIN 1 of APIC timer
748 Can be useful to work around chipset bugs
749 (in particular on some ATI chipsets).
750 The kernel tries to set a reasonable default.
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 enforcing [SELINUX] Set initial enforcing status.
753 Format: {"0" | "1"}
754 See security/selinux/Kconfig help text.
755 0 -- permissive (log only, no denials).
756 1 -- enforcing (deny and log).
757 Default value is 0.
758 Value can be changed at runtime via /selinux/enforce.
759
Huang Yinga08f82d2010-05-18 14:35:21 +0800760 erst_disable [ACPI]
761 Disable Error Record Serialization Table (ERST)
762 support.
763
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 ether= [HW,NET] Ethernet cards parameters
765 This option is obsoleted by the "netdev=" option, which
766 has equivalent usage. See its documentation for details.
767
Akinobu Mitade1ba092006-12-08 02:39:42 -0800768 failslab=
769 fail_page_alloc=
770 fail_make_request=[KNL]
771 General fault injection mechanism.
772 Format: <interval>,<probability>,<space>,<times>
773 See also /Documentation/fault-injection/.
774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 fd_mcs= [HW,SCSI]
776 See header of drivers/scsi/fd_mcs.c.
777
778 fdomain= [HW,SCSI]
779 See header of drivers/scsi/fdomain.c.
780
781 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000782 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
Alex Chiangf13ae302008-05-08 14:03:23 -0600784 force_pal_cache_flush
785 [IA-64] Avoid check_sal_cache_flush which may hang on
786 buggy SAL_CACHE_FLUSH implementations. Using this
787 parameter will force ia64_sal_cache_flush to call
788 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
789
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100790 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400791 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100792 as early as possible in order to facilitate early
793 boot debugging.
794
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200795 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400796 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200797 If no parameter is passed, ftrace will dump
798 buffers of all CPUs, but if you pass orig_cpu, it will
799 dump only the buffer of the CPU that triggered the
800 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400801
802 ftrace_filter=[function-list]
803 [FTRACE] Limit the functions traced by the function
804 tracer at boot up. function-list is a comma separated
805 list of functions. This list can be changed at run
806 time by the set_ftrace_filter file in the debugfs
807 tracing directory.
808
809 ftrace_notrace=[function-list]
810 [FTRACE] Do not trace the functions specified in
811 function-list. This list can be changed at run time
812 by the set_ftrace_notrace file in the debugfs
813 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100814
Stefan Assmann369bc182009-10-12 22:17:21 +0200815 ftrace_graph_filter=[function-list]
816 [FTRACE] Limit the top level callers functions traced
817 by the function graph tracer at boot up.
818 function-list is a comma separated list of functions
819 that can be changed at run time by the
820 set_graph_function file in the debugfs tracing directory.
821
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 gamecon.map[2|3]=
823 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
824 support via parallel port (up to 5 devices per port)
825 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
826 See also Documentation/input/joystick-parport.txt
827
828 gamma= [HW,DRM]
829
Yinghai Luaaf23042008-01-30 13:33:09 +0100830 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
831 Format: off | on
832 default: on
833
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700834 gcov_persist= [GCOV] When non-zero (default), profiling data for
835 kernel modules is saved and remains accessible via
836 debugfs, even when the module is unloaded/reloaded.
837 When zero, profiling data is discarded and associated
838 debugfs files are removed at module unload time.
839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 gdth= [HW,SCSI]
841 See header of drivers/scsi/gdth.c.
842
843 gpt [EFI] Forces disk with valid GPT signature but
844 invalid Protective MBR to be treated as GPT.
845
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 gvp11= [HW,SCSI]
847
848 hashdist= [KNL,NUMA] Large hashes allocated during boot
849 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700850 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700851 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852
853 hcl= [IA-64] SGI's Hardware Graph compatibility layer
854
855 hd= [EIDE] (E)IDE hard drive subsystem geometry
856 Format: <cyl>,<head>,<sect>
857
Huang Yingea8c0712010-05-18 14:35:15 +0800858 hest_disable [ACPI]
859 Disable Hardware Error Source Table (HEST) support;
860 corresponding firmware-first mode error processing
861 logic will be disabled.
862
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
864 size of <nn>. This works even on boxes that have no
865 highmem otherwise. This also works to reduce highmem
866 size on bigger boxes.
867
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800868 highres= [KNL] Enable/disable high resolution timer mode.
869 Valid parameters: "on", "off"
870 Default: "on"
871
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 hisax= [HW,ISDN]
873 See Documentation/isdn/README.HiSax.
874
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700875 hlt [BUGS=ARM,SH]
876
877 hpet= [X86-32,HPET] option to control HPET usage
878 Format: { enable (default) | disable | force |
879 verbose }
880 disable: disable HPET and use PIT instead
881 force: allow force enabled of undocumented chips (ICH4,
882 VIA, nVidia)
883 verbose: show contents of HPET registers during setup
884
Andi Kleenb4718e62008-07-23 21:27:51 -0700885 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
886 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700887 On x86-64 and powerpc, this option can be specified
888 multiple times interleaved with hugepages= to reserve
889 huge pages of different sizes. Valid pages sizes on
890 x86-64 are 2M (when the CPU supports "pse") and 1G
891 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700892 Note that 1GB pages can only be allocated at boot time
893 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900894
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100895 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
896 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100897 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
898 If specified, z/VM IUCV HVC accepts connections
899 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100900
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700901 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700902 or register an additional I2C bus that is not
903 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700904 Format:
905 <bus_id>,<clkrate>
906
Jiri Kosina36d95732008-10-06 02:51:09 -0400907 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200909 i8042.dumbkbd [HW] Pretend that controller can only read data from
910 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 (Don't attempt to blink the leds)
912 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500913 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400914 i8042.noloop [HW] Disable the AUX Loopback command while probing
915 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 i8042.nomux [HW] Don't check presence of an active multiplexing
917 controller
918 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
919 controllers
920 i8042.panicblink=
921 [HW] Frequency with which keyboard LEDs should blink
922 when kernel panics (default is 0.5 sec)
923 i8042.reset [HW] Reset the controller during init and cleanup
924 i8042.unlock [HW] Unlock (ignore) the keylock
925
926 i810= [HW,DRM]
927
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700928 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
929 indicates that the driver is running on unsupported
930 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
932 does not match list of supported models.
933 i8k.power_status
934 [HW] Report power status in /proc/i8k
935 (disabled by default)
936 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
937 capability is set.
938
939 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
940 See Documentation/mca.txt.
941
942 icn= [HW,ISDN]
943 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
944
David Fries0af80c02009-02-25 20:28:21 +0100945 ide-core.nodma= [HW] (E)IDE subsystem
946 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200947 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
948 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100949 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700951 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
952 Claim all unknown PCI IDE storage controllers.
953
Andi Kleenf039b752007-05-02 19:27:12 +0200954 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800955 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
956 Poll forces a polling idle loop that can slightly
957 improve the performance of waking up a idle CPU, but
958 will use a lot of power and make the system run hot.
959 Not recommended.
960 idle=mwait: On systems which support MONITOR/MWAIT but
961 the kernel chose to not use it because it doesn't save
962 as much power as a normal idle loop, use the
963 MONITOR/MWAIT idle loop anyways. Performance should be
964 the same as idle=poll.
965 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800966 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800967 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700968
Ingo Molnar792908222006-12-06 20:40:51 -0800969 ignore_loglevel [KNL]
970 Ignore loglevel setting - this will print /all/
971 kernel messages to the console. Useful for debugging.
972
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 ihash_entries= [KNL]
974 Set number of hash buckets for inode cache.
975
Mimi Zohar3323eec2009-02-04 09:06:58 -0500976 ima_audit= [IMA]
977 Format: { "0" | "1" }
978 0 -- integrity auditing messages. (Default)
979 1 -- enable informational integrity auditing messages.
980
981 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700982 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500983 default: "sha1"
984
Eric Paris5789ba32009-05-21 15:47:06 -0400985 ima_tcb [IMA]
986 Load a policy which meets the needs of the Trusted
987 Computing Base. This means IMA will measure all
988 programs exec'd, files mmap'd for exec, and all files
989 opened for read by uid=0.
990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 in2000= [HW,SCSI]
992 See header of drivers/scsi/in2000.c.
993
994 init= [KNL]
995 Format: <full_path>
996 Run specified binary instead of /sbin/init as init
997 process.
998
999 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1000 for working out where the kernel is dying during
1001 startup.
1002
1003 initrd= [BOOT] Specify the location of the initial ramdisk
1004
1005 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1006 Format: <irq>
1007
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001008 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001009 on
1010 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001011 off
1012 Disable intel iommu driver.
1013 igfx_off [Default Off]
1014 By default, gfx is mapped as normal device. If a gfx
1015 device has a dedicated DMAR unit, the DMAR unit is
1016 bypassed by not enabling DMAR with this option. In
1017 this case, gfx device will use physical address for
1018 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001019 forcedac [x86_64]
1020 With this option iommu will not optimize to look
1021 for io virtual address below 32 bit forcing dual
1022 address cycle on pci bus for cards supporting greater
1023 than 32 bit addressing. The default is to look
1024 for translation below 32 bit and if not available
1025 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001026 strict [Default Off]
1027 With this option on every unmap_single operation will
1028 result in a hardware IOTLB flush operation as opposed
1029 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001030
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001031 inttest= [IA64]
1032
1033 iomem= Disable strict checking of access to MMIO memory
1034 strict regions from userspace.
1035 relaxed
1036
1037 iommu= [x86]
1038 off
1039 force
1040 noforce
1041 biomerge
1042 panic
1043 nopanic
1044 merge
1045 nomerge
1046 forcesac
1047 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001048 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001049
1050 io7= [HW] IO7 for Marvel based alpha systems
1051 See comment before marvel_specify_io7 in
1052 arch/alpha/kernel/core_marvel.c.
1053
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301054 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001055 0x80
1056 Standard port 0x80 based delay
1057 0xed
1058 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001059 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001060 Simple two microseconds delay
1061 none
1062 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001063
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001065 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066
1067 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001068 See comment before ip2_setup() in
1069 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070
1071 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1072 See header of drivers/scsi/ips.c.
1073
Alan Cox200803d2005-06-28 20:45:18 -07001074 irqfixup [HW]
1075 When an interrupt is not handled search all handlers
1076 for it. Intended to get systems with badly broken
1077 firmware running.
1078
1079 irqpoll [HW]
1080 When an interrupt is not handled search all handlers
1081 for it. Also check all handlers each timer
1082 interrupt. Intended to get systems with badly broken
1083 firmware running.
1084
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001086 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087
1088 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001089 Format:
1090 <cpu number>,...,<cpu number>
1091 or
Li Zefanb225d442008-11-06 12:53:39 -08001092 <cpu number>-<cpu number>
1093 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001094 or a mixture
1095 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 This option can be used to specify one or more CPUs
1098 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001099 algorithms. You can move a process onto or off an
1100 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 <cpu number> begins at 0 and the maximum value is
1102 "number of CPUs in system - 1".
1103
1104 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001105 alternative -- manually setting the CPU mask of all
1106 tasks in the system -- can cause problems and
1107 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
Randy Dunlapa9913042005-10-23 12:57:11 -07001109 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110
1111 js= [HW,JOY] Analog joystick
1112 See Documentation/input/joystick.txt.
1113
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001114 keepinitrd [HW,ARM]
1115
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301116 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001117 specifies the amount of memory usable by the kernel
1118 for non-movable allocations. The requested amount is
1119 spread evenly throughout all nodes in the system. The
1120 remaining memory in each node is used for Movable
1121 pages. In the event, a node is too small to have both
1122 kernelcore and Movable pages, kernelcore pages will
1123 take priority and other nodes will have a larger number
1124 of kernelcore pages. The Movable zone is used for the
1125 allocation of pages that may be reclaimed or moved
1126 by the page migration subsystem. This means that
1127 HugeTLB pages may not be allocated from this zone.
1128 Note that allocations like PTEs-from-HighMem still
1129 use the HighMem zone if it exists, and the Normal
1130 zone if it does not.
1131
Jason Wessel4fe1da42010-05-20 21:04:31 -05001132 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1133 Format: <Controller#>[,poll interval]
1134 The controller # is the number of the ehci usb debug
1135 port as it is probed via PCI. The poll interval is
1136 optional and is the number seconds in between
1137 each poll cycle to the debug port in case you need
1138 the functionality for interrupting the kernel with
1139 gdb or control-c on the dbgp connection. When
1140 not using this parameter you use sysrq-g to break into
1141 the kernel debugger.
1142
Jason Wessel84c08fd2010-05-20 21:04:24 -05001143 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001144 Requires a tty driver that supports console polling,
1145 or a supported polling keyboard driver (non-usb).
1146 Serial only format: <serial_device>[,baud]
1147 keyboard only format: kbd
1148 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001149
Jason Wessel84c08fd2010-05-20 21:04:24 -05001150 kgdbwait [KGDB] Stop kernel execution and enter the
1151 kernel debugger at the earliest opportunity.
1152
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001153 kmac= [MIPS] korina ethernet MAC address.
1154 Configure the RouterBoard 532 series on-chip
1155 Ethernet adapter MAC address.
1156
Catalin Marinas04f70332009-06-11 13:22:39 +01001157 kmemleak= [KNL] Boot-time kmemleak enable/disable
1158 Valid arguments: on, off
1159 Default: on
1160
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301161 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001162 in oops dumps.
1163
Andre Przywarafef07aa2009-07-10 14:20:35 +02001164 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1165 Default is 0 (don't ignore, but inject #GP)
1166
1167 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1168 Default is 1 (enabled)
1169
1170 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1171 Default is 0 (off)
1172
1173 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1174 for all guests.
1175 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1176
1177 kvm-intel.bypass_guest_pf=
1178 [KVM,Intel] Disables bypassing of guest page faults
1179 on Intel chips. Default is 1 (enabled)
1180
1181 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1182 (virtualized MMU) support on capable Intel chips.
1183 Default is 1 (enabled)
1184
1185 kvm-intel.emulate_invalid_guest_state=
1186 [KVM,Intel] Enable emulation of invalid guest states
1187 Default is 0 (disabled)
1188
1189 kvm-intel.flexpriority=
1190 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1191 Default is 1 (enabled)
1192
1193 kvm-intel.unrestricted_guest=
1194 [KVM,Intel] Disable unrestricted guest feature
1195 (virtualized real and unpaged mode) on capable
1196 Intel chips. Default is 1 (enabled)
1197
1198 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1199 feature (tagged TLBs) on capable Intel chips.
1200 Default is 1 (enabled)
1201
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 l2cr= [PPC]
1203
Robert Brosea78bfbf2008-03-29 07:20:23 +11001204 l3cr= [PPC]
1205
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001206 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001207 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301209 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001210 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001211
FD Camifcb71f62008-01-06 19:08:56 +01001212 libata.dma= [LIBATA] DMA control
1213 libata.dma=0 Disable all PATA and SATA DMA
1214 libata.dma=1 PATA and SATA Disk DMA only
1215 libata.dma=2 ATAPI (CDROM) DMA only
1216 libata.dma=4 Compact Flash DMA only
1217 Combinations also work, so libata.dma=3 enables DMA
1218 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001219
1220 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1221 libata.ignore_hpa=0 keep BIOS limits (default)
1222 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001223
Dave Jones78e70c22007-09-27 11:50:13 -04001224 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1225 when set.
1226 Format: <int>
1227
Tejun Heo33267322008-02-13 09:15:09 +09001228 libata.force= [LIBATA] Force configurations. The format is comma
1229 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001230 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001231 matching port, link or device. Basically, it matches
1232 the ATA ID string printed on console by libata. If
1233 the whole ID part is omitted, the last PORT and DEVICE
1234 values are used. If ID hasn't been specified yet, the
1235 configuration applies to all ports, links and devices.
1236
1237 If only DEVICE is omitted, the parameter applies to
1238 the port and all links and devices behind it. DEVICE
1239 number of 0 either selects the first device or the
1240 first fan-out link behind PMP device. It does not
1241 select the host link. DEVICE number of 15 selects the
1242 host link and device attached to it.
1243
1244 The VAL specifies the configuration to force. As long
1245 as there's no ambiguity shortcut notation is allowed.
1246 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1247 The following configurations can be forced.
1248
1249 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1250 Any ID with matching PORT is used.
1251
1252 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1253
1254 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1255 udma[/][16,25,33,44,66,100,133] notation is also
1256 allowed.
1257
1258 * [no]ncq: Turn on or off NCQ.
1259
Tejun Heo05944bd2008-08-13 20:19:09 +09001260 * nohrst, nosrst, norst: suppress hard, soft
1261 and both resets.
1262
Tejun Heo43c9c592010-05-23 12:59:11 +02001263 * dump_id: dump IDENTIFY data.
1264
Tejun Heo33267322008-02-13 09:15:09 +09001265 If there are multiple matching configurations changing
1266 the same attribute, the last one is used.
1267
Randy Dunlap7c4be252009-01-06 14:42:44 -08001268 lmb=debug [KNL] Enable lmb debug messages.
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001271 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001273 lockd.nlm_grace_period=P [NFS] Assign grace period.
1274 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001276 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1277 Format: <integer>
1278
1279 lockd.nlm_timeout=T [NFS] Assign timeout value.
1280 Format: <integer>
1281
1282 lockd.nlm_udpport=M [NFS] Assign UDP port.
1283 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
1285 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1286 Format: <irq>
1287
1288 loglevel= All Kernel Messages with a loglevel smaller than the
1289 console loglevel will be printed to the console. It can
1290 also be changed with klogd or other programs. The
1291 loglevels are defined as follows:
1292
1293 0 (KERN_EMERG) system is unusable
1294 1 (KERN_ALERT) action must be taken immediately
1295 2 (KERN_CRIT) critical conditions
1296 3 (KERN_ERR) error conditions
1297 4 (KERN_WARNING) warning conditions
1298 5 (KERN_NOTICE) normal but significant condition
1299 6 (KERN_INFO) informational
1300 7 (KERN_DEBUG) debug-level messages
1301
1302 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001303 Format: { n | nk | nM }
1304 n must be a power of two. The default size
1305 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
Randy Dunlapaccaa242007-10-16 01:29:37 -07001307 logo.nologo [FB] Disables display of the built-in Linux logo.
1308 This may be used to provide more screen space for
1309 kernel log messages and is useful when debugging
1310 kernel boot problems.
1311
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 lp=0 [LP] Specify parallel ports to use, e.g,
1313 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1314 lp=reset first parallel port). 'lp=0' disables the
1315 lp=auto printer driver. 'lp=reset' (which can be
1316 specified in addition to the ports) causes
1317 attached printers to be reset. Using
1318 lp=port1,port2,... specifies the parallel ports
1319 to associate lp devices with, starting with
1320 lp0. A port specification may be 'none' to skip
1321 that lp device, or a parport name such as
1322 'parport0'. Specifying 'lp=auto' instead of a
1323 port specification list means that device IDs
1324 from each port should be examined, to see if
1325 an IEEE 1284-compliant printer is attached; if
1326 so, the driver will manage that printer.
1327 See also header of drivers/char/lp.c.
1328
1329 lpj=n [KNL]
1330 Sets loops_per_jiffy to given constant, thus avoiding
1331 time-consuming boot-time autodetection (up to 250 ms per
1332 CPU). 0 enables autodetection (default). To determine
1333 the correct value for your kernel, boot with normal
1334 autodetection and see what value is printed. Note that
1335 on SMP systems the preset will be applied to all CPUs,
1336 which is likely to cause problems if your CPUs need
1337 significantly divergent settings. An incorrect value
1338 will cause delays in the kernel to be wrong, leading to
1339 unpredictable I/O errors and other breakage. Although
1340 unlikely, in the extreme case this might damage your
1341 hardware.
1342
1343 ltpc= [NET]
1344 Format: <io>,<irq>,<dma>
1345
Randy Dunlapa9913042005-10-23 12:57:11 -07001346 mac5380= [HW,SCSI] Format:
1347 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348
Randy Dunlapa9913042005-10-23 12:57:11 -07001349 machvec= [IA64] Force the use of a particular machine-vector
1350 (machvec) in a generic kernel.
1351 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
Wu Zhangjin3209e702009-07-02 23:27:12 +08001353 machtype= [Loongson] Share the same kernel image file between different
1354 yeeloong laptop.
1355 Example: machtype=lemote-yeeloong-2f-7inch
1356
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001357 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1358 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359
1360 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001361 should make use of. maxcpus=n : n >= 0 limits the
1362 kernel to using 'n' processors. n=0 is a special case,
1363 it is equivalent to "nosmp", which also disables
1364 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001366 max_loop= [LOOP] Maximum number of loopback devices that can
1367 be mounted
1368 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001369
Randy Dunlapa9913042005-10-23 12:57:11 -07001370 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 Should be between 1 and 2^32-1.
1372
1373 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001374 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 Should be between 1 and 16384.
1376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 mcatest= [IA-64]
1378
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001379 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
Uwe Hermann71cced62008-10-20 09:32:21 -07001381 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001382
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 md= [HW] RAID subsystems devices and level
1384 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 mdacon= [MDA]
1387 Format: <first>,<last>
1388 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1391 Amount of memory to be used when the kernel is not able
1392 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001393 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 address space collisions. Without memmap= PCI devices
1395 could be placed at addresses belonging to unused RAM.
1396
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001397 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 memory.
1399
Paul Mundt6902aa82008-09-21 17:14:42 +09001400 memchunk=nn[KMG]
1401 [KNL,SH] Allow user to override the default size for
1402 per-device physically contiguous DMA buffers.
1403
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301404 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 E820 memory map, as specified by the user.
1406 Such memmap=exactmap lines can be constructed based on
1407 BIOS output or other requirements. See the memmap=nn@ss
1408 option description.
1409
1410 memmap=nn[KMG]@ss[KMG]
1411 [KNL] Force usage of a specific region of memory
1412 Region of memory to be used, from ss to ss+nn.
1413
1414 memmap=nn[KMG]#ss[KMG]
1415 [KNL,ACPI] Mark specific memory as ACPI data.
1416 Region of memory to be used, from ss to ss+nn.
1417
1418 memmap=nn[KMG]$ss[KMG]
1419 [KNL,ACPI] Mark specific memory as reserved.
1420 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001421 Example: Exclude memory from 0x18690000-0x1869ffff
1422 memmap=64K$0x18690000
1423 or
1424 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001426 memory_corruption_check=0/1 [X86]
1427 Some BIOSes seem to corrupt the first 64k of
1428 memory when doing things like suspend/resume.
1429 Setting this option will scan the memory
1430 looking for corruption. Enabling this will
1431 both detect corruption and prevent the kernel
1432 from using the memory being corrupted.
1433 However, its intended as a diagnostic tool; if
1434 repeatable BIOS-originated corruption always
1435 affects the same memory, you can use memmap=
1436 to prevent the kernel from using that memory.
1437
1438 memory_corruption_check_size=size [X86]
1439 By default it checks for corruption in the low
1440 64k, making this memory unavailable for normal
1441 use. Use this parameter to scan for
1442 corruption in more or less memory.
1443
1444 memory_corruption_check_period=seconds [X86]
1445 By default it checks for corruption every 60
1446 seconds. Use this parameter to check at some
1447 other rate. 0 disables periodic checking.
1448
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001449 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001450 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001451 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001452 Specifies the number of memtest passes to be
1453 performed. Each pass selects another test
1454 pattern from a given set of patterns. Memtest
1455 fills the memory with this pattern, validates
1456 memory contents and reserves bad memory
1457 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001458
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 meye.*= [HW] Set MotionEye Camera parameters
1460 See Documentation/video4linux/meye.txt.
1461
Andres Salomon8f368812007-10-12 23:04:06 +02001462 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1463 Multi-Function General Purpose Timers on AMD Geode
1464 platforms.
1465
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001466 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1467 the BIOS has incorrectly applied a workaround. TinyBIOS
1468 version 0.98 is known to be affected, 0.99 fixes the
1469 problem by letting the user disable the workaround.
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 mga= [HW,DRM]
1472
Randy Dunlap1c207f952008-11-19 15:36:16 -08001473 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1474 physical address is ignored.
1475
Michel Pollet39f45d72009-05-20 11:10:31 +01001476 mini2440= [ARM,HW,KNL]
1477 Format:[0..2][b][c][t]
1478 Default: "0tb"
1479 MINI2440 configuration specification:
1480 0 - The attached screen is the 3.5" TFT
1481 1 - The attached screen is the 7" TFT
1482 2 - The VGA Shield is attached (1024x768)
1483 Leaving out the screen size parameter will not load
1484 the TFT driver, and the framebuffer will be left
1485 unconfigured.
1486 b - Enable backlight. The TFT backlight pin will be
1487 linked to the kernel VESA blanking code and a GPIO
1488 LED. This parameter is not necessary when using the
1489 VGA shield.
1490 c - Enable the s3c camera interface.
1491 t - Reserved for enabling touchscreen support. The
1492 touchscreen support is not enabled in the mainstream
1493 kernel as of 2.6.30, a preliminary port can be found
1494 in the "bleeding edge" mini2440 support kernel at
1495 http://repo.or.cz/w/linux-2.6/mini2440.git
1496
Mel Gorman6b74ab92008-07-23 21:26:49 -07001497 mminit_loglevel=
1498 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1499 parameter allows control of the logging verbosity for
1500 the additional memory initialisation checks. A value
1501 of 0 disables mminit logging and a level of 4 will
1502 log everything. Information is printed at KERN_DEBUG
1503 so loglevel=8 may also need to be specified.
1504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 mousedev.tap_time=
1506 [MOUSE] Maximum time between finger touching and
1507 leaving touchpad surface for touch to be considered
1508 a tap and be reported as a left button click (for
1509 touchpads working in absolute mode only).
1510 Format: <msecs>
1511 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1512 reporting absolute coordinates, such as tablets
1513 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1514 reporting absolute coordinates, such as tablets
1515
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301516 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001517 is similar to kernelcore except it specifies the
1518 amount of memory used for migratable allocations.
1519 If both kernelcore and movablecore is specified,
1520 then kernelcore will be at *least* the specified
1521 value but may be more. If movablecore on its own
1522 is specified, the administrator must be careful
1523 that the amount of memory usable for all allocations
1524 is not too small.
1525
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 mpu401= [HW,OSS]
1527 Format: <io>,<irq>
1528
1529 MTD_Partition= [MTD]
1530 Format: <name>,<region-number>,<size>,<offset>
1531
Randy Dunlapa9913042005-10-23 12:57:11 -07001532 MTD_Region= [MTD] Format:
1533 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
1535 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001536 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001538 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1539
1540 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1541
1542 boundary - index of last SLC block on Flex-OneNAND.
1543 The remaining blocks are configured as MLC blocks.
1544 lock - Configure if Flex-OneNAND boundary should be locked.
1545 Once locked, the boundary cannot be changed.
1546 1 indicates lock status, 0 indicates unlock status.
1547
Ben Dooks9db829f2008-07-03 11:24:29 +01001548 mtdset= [ARM]
1549 ARM/S3C2412 JIVE boot control
1550
1551 See arch/arm/mach-s3c2412/mach-jive.c
1552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001554 [HW] Make the MicroTouch USB driver use raw coordinates
1555 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001557 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001558 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001559 that could hold holes aka. UC entries.
1560
1561 mtrr_gran_size=nn[KMG] [X86]
1562 Used for mtrr cleanup. It is granularity of mtrr block.
1563 Default is 1.
1564 Large value could prevent small alignment from
1565 using up MTRRs.
1566
1567 mtrr_spare_reg_nr=n [X86]
1568 Format: <integer>
1569 Range: 0,7 : spare reg number
1570 Default : 1
1571 Used for mtrr cleanup. It is spare mtrr entries number.
1572 Set to 2 or more if your graphical card needs more.
1573
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1575
1576 NCR_D700= [HW,SCSI]
1577 See header of drivers/scsi/NCR_D700.c.
1578
1579 ncr5380= [HW,SCSI]
1580
1581 ncr53c400= [HW,SCSI]
1582
1583 ncr53c400a= [HW,SCSI]
1584
1585 ncr53c406a= [HW,SCSI]
1586
1587 ncr53c8xx= [HW,SCSI]
1588
1589 netdev= [NET] Network devices parameters
1590 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1591 Note that mem_start is often overloaded to mean
1592 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001593 This usage is only documented in each driver source
1594 file if at all.
1595
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001596 nf_conntrack.acct=
1597 [NETFILTER] Enable connection tracking flow accounting
1598 0 to disable accounting
1599 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001600 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001601
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001603 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
1605 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001606 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607
Trond Myklebusta72b4422006-01-03 09:55:41 +01001608 nfs.callback_tcpport=
1609 [NFS] set the TCP port on which the NFSv4 callback
1610 channel should listen.
1611
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001612 nfs.cache_getent=
1613 [NFS] sets the pathname to the program which is used
1614 to update the NFS client cache entries.
1615
1616 nfs.cache_getent_timeout=
1617 [NFS] sets the timeout after which an attempt to
1618 update a cache entry is deemed to have failed.
1619
Trond Myklebust58df0952006-01-03 09:55:57 +01001620 nfs.idmap_cache_timeout=
1621 [NFS] set the maximum lifetime for idmapper cache
1622 entries.
1623
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001624 nfs.enable_ino64=
1625 [NFS] enable 64-bit inode numbers.
1626 If zero, the NFS client will fake up a 32-bit inode
1627 number for the readdir() and stat() syscalls instead
1628 of returning the full 64-bit number.
1629 The default is to return 64-bit inode numbers.
1630
Paul Mundt1e1030d2009-09-01 17:38:32 +09001631 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001632 when a NMI is triggered.
1633 Format: [state][,regs][,debounce][,die]
1634
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301635 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001636 Format: [panic,][num]
1637 Valid num: 0,1,2
1638 0 - turn nmi_watchdog off
1639 1 - use the IO-APIC timer for the NMI watchdog
1640 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001641 a performance counter. Note: This will use one
1642 performance counter and the local APIC's performance
1643 vector.
1644 When panic is specified, panic when an NMI watchdog
1645 timeout occurs.
1646 This is useful when you use a panic=... timeout and
1647 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001648 Instead of 1 and 2 it is possible to use the following
1649 symbolic names: lapic and ioapic
1650 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
Anton Vorontsovbff38772009-07-08 11:10:56 -07001652 netpoll.carrier_timeout=
1653 [NET] Specifies amount of time (in seconds) that
1654 netpoll should wait for a carrier. By default netpoll
1655 waits 4 seconds.
1656
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001657 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 emulation library even if a 387 maths coprocessor
1659 is present.
1660
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001661 no_console_suspend
1662 [HW] Never suspend the console
1663 Disable suspending of consoles during suspend and
1664 hibernate operations. Once disabled, debugging
1665 messages can reach various consoles while the rest
1666 of the system is being put to sleep (ie, while
1667 debugging driver suspend/resume hooks). This may
1668 not work reliably with all consoles, but is known
1669 to work with serial and VGA consoles.
1670
Christoph Lameterc1aee212007-05-31 00:40:47 -07001671 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1672 caches in the slab allocator. Saves per-node memory,
1673 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001674
Randy Dunlapa9913042005-10-23 12:57:11 -07001675 noalign [KNL,ARM]
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 noapic [SMP,APIC] Tells the kernel to not make use of any
1678 IOAPICs that may be present in the system.
1679
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 nobats [PPC] Do not use BATs for mapping kernel lowmem
1681 on "Classic" PPC cores.
1682
1683 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001684
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001685 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1686
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001687 nodelayacct [KNL] Disable per-task delay accounting
1688
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1690
Paul Mundt6902aa82008-09-21 17:14:42 +09001691 nodsp [SH] Disable hardware DSP at boot time.
1692
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301693 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001694
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 noexec [IA-64]
1696
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301697 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001698 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001700 noexec=off: disable non-executable mappings
1701
1702 noexec32 [X86-64]
1703 This affects only 32-bit executables.
1704 noexec32=on: enable non-executable mappings (default)
1705 read doesn't imply executable mappings
1706 noexec32=off: disable non-executable mappings
1707 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708
Paul Mundt6902aa82008-09-21 17:14:42 +09001709 nofpu [SH] Disable hardware FPU at boot time.
1710
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001711 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001712 register save and restore. The kernel will only save
1713 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714
Suresh Siddha0c752a92009-05-22 12:17:45 -07001715 noxsave [BUGS=X86] Disables x86 extended register state save
1716 and restore using xsave. The kernel will fallback to
1717 enabling legacy floating-point and sse state.
1718
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001719 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1720 wfi(ARM) instruction doesn't work correctly and not to
1721 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001722
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001723 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724 instruction doesn't work correctly and not to
1725 use it.
1726
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001727 no_file_caps Tells the kernel not to honor file capabilities. The
1728 only way then for a file to be executed with privilege
1729 is to be setuid root or executed by root.
1730
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 nohalt [IA-64] Tells the kernel not to use the power saving
1732 function PAL_HALT_LIGHT when idle. This increases
1733 power-consumption. On the positive side, it reduces
1734 interrupt wake-up latency, which may improve performance
1735 in certain environments such as networked servers or
1736 real-time systems.
1737
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001738 nohz= [KNL] Boottime enable/disable dynamic ticks
1739 Valid arguments: on, off
1740 Default: on
1741
Paul Mundteeee7852009-04-02 12:31:16 +09001742 noiotrap [SH] Disables trapped I/O port accesses.
1743
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001744 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 disable unhandled interrupt sources.
1746
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301747 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001748 broken timer IRQ sources.
1749
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 noisapnp [ISAPNP] Disables ISA PnP code.
1751
1752 noinitrd [RAM] Tells the kernel not to load any configured
1753 initial RAM disk.
1754
Weidong Han03ea8152009-04-17 16:42:15 +08001755 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1756 remapping.
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 nointroute [IA-64]
1759
Tony Luck0aa366f2007-07-20 11:22:30 -07001760 nojitter [IA64] Disables jitter checking for ITC timers.
1761
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001762 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001765
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 noltlbs [PPC] Do not use large page/tlb entries for kernel
1767 lowmem mapping on PPC40x.
1768
Horms312f1f02006-02-22 09:57:55 +09001769 nomca [IA-64] Disable machine check abort handling
1770
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001771 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001772
Andres Salomon83d73842007-10-12 23:04:06 +02001773 nomfgpt [X86-32] Disable Multi-Function General Purpose
1774 Timer usage (for AMD Geode machines).
1775
Jiri Kosina016ddd92010-01-18 17:05:40 +01001776 nopat [X86] Disable PAT (page attribute table extension of
1777 pagetables) support.
1778
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001779 norandmaps Don't use address space randomization. Equivalent to
1780 echo 0 > /proc/sys/kernel/randomize_va_space
1781
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001782 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001783
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001784 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001785 with UP alternatives
1786
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 noresidual [PPC] Don't use residual data on PReP machines.
1788
Randy Dunlapa9913042005-10-23 12:57:11 -07001789 noresume [SWSUSP] Disables resume and restores original swap
1790 space.
1791
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 no-scroll [VGA] Disables scrollback.
1793 This is required for the Braillex ib80-piezo Braille
1794 reader made by F.H. Papenmeier (Germany).
1795
1796 nosbagart [IA-64]
1797
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001798 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001799
Len Brown61ec7562007-08-16 03:34:22 -04001800 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1801 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802
Dave Jones97842212007-07-15 23:41:05 -07001803 nosoftlockup [KNL] Disable the soft-lockup detector.
1804
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001805 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001806 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001807
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808 nosync [HW,M68K] Disables sync negotiation for all devices.
1809
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001810 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
1812 nousb [USB] Disable the USB subsystem
1813
1814 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001815
Weidong Han2b2fd872009-04-17 16:42:12 +08001816 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1817
Fenghua Yua6c75b862008-03-14 13:57:08 -07001818 nptcg= [IA64] Override max number of concurrent global TLB
1819 purges which is reported from either PAL_VM_SUMMARY or
1820 SAL PALO.
1821
Yinghai Lu2b633e32010-02-10 01:20:37 -08001822 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1823 could support. nr_cpus=n : n >= 1 limits the kernel to
1824 supporting 'n' processors. Later in runtime you can not
1825 use hotplug cpu feature to put more cpu back to online.
1826 just like you compile the kernel NR_CPUS=n
1827
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001828 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1829
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001830 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1831 one of ['zone', 'node', 'default'] can be specified
1832 This can be set from sysctl after boot.
1833 See Documentation/sysctl/vm.txt for details.
1834
Randy Dunlap7c4be252009-01-06 14:42:44 -08001835 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1836 See Documentation/debugging-via-ohci1394.txt for more
1837 info.
1838
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001839 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1840 Rather than timing out after 20 ms if an EC
1841 command is not properly ACKed, override the length
1842 of the timeout. We have interrupts disabled while
1843 waiting for the ACK, so if this is set too high
1844 interrupts *may* be lost!
1845
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001846 omap_mux= [OMAP] Override bootloader pin multiplexing.
1847 Format: <mux_mode0.mode_name=value>...
1848 For example, to override I2C bus2:
1849 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1850
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851 opl3= [HW,OSS]
1852 Format: <io>
1853
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 oprofile.timer= [HW]
1855 Use timer interrupt instead of performance counters
1856
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001857 oprofile.cpu_type= Force an oprofile cpu type
1858 This might be useful if you have an older oprofile
1859 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001860 Format: { arch_perfmon }
1861 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001862 perfmon on Intel CPUs instead of the
1863 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001864
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 osst= [HW,SCSI] SCSI Tape Driver
1866 Format: <buffer_size>,<write_threshold>
1867 See also Documentation/scsi/st.txt.
1868
1869 panic= [KNL] Kernel behaviour on panic
1870 Format: <timeout>
1871
1872 parkbd.port= [HW] Parallel port number the keyboard adapter is
1873 connected to, default is 0.
1874 Format: <parport#>
1875 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1876 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001877 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878
Randy Dunlapa9913042005-10-23 12:57:11 -07001879 parport= [HW,PPT] Specify parallel ports. 0 disables.
1880 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1881 Use 'auto' to force the driver to use any
1882 IRQ/DMA settings detected (the default is to
1883 ignore detected IRQ/DMA settings because of
1884 possible conflicts). You can specify the base
1885 address, IRQ, and DMA settings; IRQ and DMA
1886 should be numbers, or 'auto' (for using detected
1887 settings on that particular port), or 'nofifo'
1888 (to avoid using a FIFO even if it is detected).
1889 Parallel ports are assigned in the order they
1890 are specified on the command line, starting
1891 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892
Randy Dunlapa9913042005-10-23 12:57:11 -07001893 parport_init_mode= [HW,PPT]
1894 Configure VIA parallel port to operate in
1895 a specific mode. This is necessary on Pegasos
1896 computer where firmware has no options for setting
1897 up parallel port mode and sets it to spp.
1898 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 Format: [spp|ps2|epp|ecp|ecpepp]
1900
Randy Dunlapa9913042005-10-23 12:57:11 -07001901 pas2= [HW,OSS] Format:
1902 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1903
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904 pas16= [HW,SCSI]
1905 See header of drivers/scsi/pas16.c.
1906
Andrew Mortondd287792006-03-23 03:00:57 -08001907 pause_on_oops=
1908 Halt all CPUs after the first oops has been printed for
1909 the specified number of seconds. This is to be used if
1910 your oopses keep scrolling off the screen.
1911
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 pcbit= [HW,ISDN]
1913
1914 pcd. [PARIDE]
1915 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001916 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917
Randy Dunlapa9913042005-10-23 12:57:11 -07001918 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001919 earlydump [X86] dump PCI config space before the kernel
1920 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001921 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001922 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001923 the hardware directly. Use this if your machine
1924 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001925 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001926 hardware access methods are allowed. Use this
1927 if you experience crashes upon bootup and you
1928 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001929 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001930 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001931 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001932 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001933 noaer [PCIE] If the PCIEAER kernel config parameter is
1934 enabled, this kernel boot option can be used to
1935 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001936 nodomains [PCI] Disable support for multiple PCI
1937 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301938 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001939 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001940 check_enable_amd_mmconf [X86] check for and enable
1941 properly configured MMIO access to PCI
1942 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001943 nomsi [MSI] If the PCI_MSI kernel config parameter is
1944 enabled, this kernel boot option can be used to
1945 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001946 noioapicquirk [APIC] Disable all boot interrupt quirks.
1947 Safety option to keep boot IRQs enabled. This
1948 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001949 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1950 primary IO-APIC for bridges that cannot disable
1951 boot IRQs. This fixes a source of spurious IRQs
1952 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001953 noioapicreroute [APIC] Disable workaround that uses the
1954 boot IRQ equivalent of an IRQ that connects to
1955 a chipset where boot IRQs cannot be disabled.
1956 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001957 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001958 routing table. These calls are known to be buggy
1959 on several machines and they hang the machine
1960 when used, but on other computers it's the only
1961 way to get the interrupt routing table. Try
1962 this option if the kernel is unable to allocate
1963 IRQs or discover secondary PCI buses on your
1964 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001965 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001966 Use with caution as certain devices share
1967 address decoders between ROMs and other
1968 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001969 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001970 expansion ROMs that do not already have
1971 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001972 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001973 assigned automatically to PCI devices. You can
1974 make the kernel exclude IRQs of your ISA cards
1975 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001976 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001977 of the PIRQ table (normally generated
1978 by the BIOS) if it is outside the
1979 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001980 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001981 useful if the kernel is unable to find your
1982 secondary buses and you want to tell it
1983 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001984 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001985 numbers ourselves, overriding
1986 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001987 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001988 in the BIOS $PIR table. This is needed on
1989 some systems with broken BIOSes, notably
1990 some HP Pavilion N5400 and Omnibook XE3
1991 notebooks. This will have no effect if ACPI
1992 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001993 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001994 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001995 use_crs [X86] Use PCI host bridge window information
1996 from ACPI. On BIOSes from 2008 or later, this
1997 is enabled by default. If you need to use this,
1998 please report a bug.
1999 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2000 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002001 routeirq Do IRQ routing for all PCI devices.
2002 This is normally done in pci_enable_device(),
2003 so this option is a temporary workaround
2004 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002005 skip_isa_align [X86] do not align io start addr, so can
2006 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002007 firmware [ARM] Do not re-enumerate the bus but instead
2008 just use the configuration from the
2009 bootloader. This is currently used on
2010 IXP2000 systems where the bus has to be
2011 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002012 noearly [X86] Don't do any early type 1 scanning.
2013 This might help on some broken boards which
2014 machine check when some devices' config space
2015 is read. But various workarounds are disabled
2016 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002017 bfsort Sort PCI devices into breadth-first order.
2018 This sorting is done to get a device
2019 order compatible with older (<= 2.4) kernels.
2020 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002021 cbiosize=nn[KMG] The fixed amount of bus space which is
2022 reserved for the CardBus bridge's IO window.
2023 The default value is 256 bytes.
2024 cbmemsize=nn[KMG] The fixed amount of bus space which is
2025 reserved for the CardBus bridge's memory
2026 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002027 resource_alignment=
2028 Format:
2029 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2030 Specifies alignment and device to reassign
2031 aligned memory resources.
2032 If <order of align> is not specified,
2033 PAGE_SIZE is used as alignment.
2034 PCI-PCI bridge can be specified, if resource
2035 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002036 ecrc= Enable/disable PCIe ECRC (transaction layer
2037 end-to-end CRC checking).
2038 bios: Use BIOS/firmware settings. This is the
2039 the default.
2040 off: Turn ECRC off
2041 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002042
Chuck Ebberte5665a42008-09-24 20:40:34 -04002043 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2044 Management.
2045 off Disable ASPM.
2046 force Enable ASPM even on devices that claim not to support it.
2047 WARNING: Forcing ASPM on may cause system lockups.
2048
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002049 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2050 off Do not use native PCIe PME signaling.
2051 force Use native PCIe PME signaling even if the BIOS refuses
2052 to allow the kernel to control the relevant PCIe config
2053 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002054 nomsi Do not use MSI for native PCIe PME signaling (this makes
2055 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002056
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 pcmv= [HW,PCMCIA] BadgePAD 4
2058
2059 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002060 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061
2062 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2063 boot time.
2064 Format: { 0 | 1 }
2065 See arch/parisc/kernel/pdc_chassis.c
2066
Tejun Heof58dc012009-08-14 15:00:50 +09002067 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002068 Currently supported values are "embed" and "page".
2069 Archs may support subset or none of the selections.
2070 See comments in mm/percpu.c for details on each
2071 allocator. This parameter is primarily for debugging
2072 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002073
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002075 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076
2077 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002078 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079
2080 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002081 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002082
2083 plip= [PPT,NET] Parallel port network link
2084 Format: { parport<nr> | timid | 0 }
2085 See also Documentation/parport.txt.
2086
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002087 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2088 Override pmtimer IOPort with a hex value.
2089 e.g. pmtmr=0x508
2090
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002091 pnp.debug [PNP]
2092 Enable PNP debug messages. This depends on the
2093 CONFIG_PNP_DEBUG_MESSAGES option.
2094
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095 pnpacpi= [ACPI]
2096 { off }
2097
2098 pnpbios= [ISAPNP]
2099 { on | off | curr | res | no-curr | no-res }
2100
2101 pnp_reserve_irq=
2102 [ISAPNP] Exclude IRQs for the autoconfiguration
2103
2104 pnp_reserve_dma=
2105 [ISAPNP] Exclude DMAs for the autoconfiguration
2106
2107 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002108 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109
2110 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002111 [ISAPNP] Exclude memory regions for the
2112 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 Ranges are in pairs (memory base and size).
2114
Randy Dunlap4af94f32009-04-17 18:30:28 -07002115 ports= [IP_VS_FTP] IPVS ftp helper module
2116 Default is 21.
2117 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2118 may be specified.
2119 Format: <port>,<port>....
2120
Ingo Molnar45807a12007-07-15 23:40:10 -07002121 print-fatal-signals=
2122 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002123
2124 If enabled, warn about various signal handling
2125 related application anomalies: too many signals,
2126 too many POSIX.1 timers, fatal signals causing a
2127 coredump - etc.
2128
2129 If you hit the warning due to signal overflow,
2130 you might want to try "ulimit -i unlimited".
2131
Ingo Molnar45807a12007-07-15 23:40:10 -07002132 default: off.
2133
Randy Dunlape84845c2007-07-15 23:40:25 -07002134 printk.time= Show timing data prefixed to each printk message line
2135 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2136
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002137 processor.max_cstate= [HW,ACPI]
2138 Limit processor to maximum C-state
2139 max_cstate=9 overrides any DMI blacklist limit.
2140
2141 processor.nocst [HW,ACPI]
2142 Ignore the _CST method to determine C-states,
2143 instead using the legacy FADT method
2144
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002146 Format: [schedule,]<number>
2147 Param: "schedule" - profile schedule points.
2148 Param: <number> - step/bucket size as a power of 2 for
2149 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002150 Param: "sleep" - profile D-state sleeping (millisecs).
2151 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002152 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2155 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002156 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157
Randy Dunlapa9913042005-10-23 12:57:11 -07002158 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2159 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2161 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002162 psmouse.resetafter= [HW,MOUSE]
2163 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 (0 = never).
2165 psmouse.resolution=
2166 [HW,MOUSE] Set desired mouse resolution, in dpi.
2167 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002168 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169 0 = disabled, 1 = enabled (default).
2170
2171 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002172 Format:
2173 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
2175 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002176 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177
Kay Sieversdc8c8582007-08-15 12:25:38 +02002178 pty.legacy_count=
2179 [KNL] Number of legacy pty's. Overwrites compiled-in
2180 default number.
2181
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002182 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002183
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 r128= [HW,DRM]
2185
2186 raid= [HW,RAID]
2187 See Documentation/md.txt.
2188
Randy Dunlapa9913042005-10-23 12:57:11 -07002189 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002190 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002191
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002193 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002195 rcupdate.blimit= [KNL,BOOT]
2196 Set maximum number of finished RCU callbacks to process
2197 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002198
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002199 rcupdate.qhimark= [KNL,BOOT]
2200 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002201 RCU callbacks over which batch limiting is disabled.
2202
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002203 rcupdate.qlowmark= [KNL,BOOT]
2204 Set threshold of queued RCU callbacks below which
2205 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002206
Olof Johanssonffdfc402005-09-06 15:17:19 -07002207 rdinit= [KNL]
2208 Format: <full_path>
2209 Run specified binary instead of /init from the ramdisk,
2210 used for early userspace startup. See initrd.
2211
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002212 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002214 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215
Paul Jackson46b6d942008-07-04 10:00:09 -07002216 relax_domain_level=
2217 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002218 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002219
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2221
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002222 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07002223 Format: nn[KMG]
2224 Reserves a hole at the top of the kernel virtual
2225 address space.
2226
Vivek Goyal7e962872006-09-27 01:50:44 -07002227 reset_devices [KNL] Force drivers to reset the underlying device
2228 during initialization.
2229
Randy Dunlapa9913042005-10-23 12:57:11 -07002230 resume= [SWSUSP]
2231 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002233 resume_offset= [SWSUSP]
2234 Specify the offset from the beginning of the partition
2235 given by "resume=" at which the swap header is located,
2236 in <PAGE_SIZE> units (needed only for swap files).
2237 See Documentation/power/swsusp-and-swap-files.txt
2238
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002239 retain_initrd [RAM] Keep initrd memory after extraction
2240
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 rhash_entries= [KNL,NET]
2242 Set number of hash buckets for route cache
2243
2244 riscom8= [HW,SERIAL]
2245 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2246
2247 ro [KNL] Mount root device read-only on boot
2248
2249 root= [KNL] Root filesystem
2250
2251 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2252 mount the root filesystem
2253
2254 rootflags= [KNL] Set root filesystem mount option string
2255
2256 rootfstype= [KNL] Set root filesystem type
2257
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002258 rootwait [KNL] Wait (indefinitely) for root device to show up.
2259 Useful for devices that are detected asynchronously
2260 (e.g. USB and MMC devices).
2261
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 rw [KNL] Mount root device read-write on boot
2263
2264 S [KNL] Run init in single mode
2265
2266 sa1100ir [NET]
2267 See drivers/net/irda/sa1100_ir.c.
2268
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002270
Mike Travisf6630112009-11-17 18:22:15 -06002271 sched_debug [KNL] Enables verbose scheduler debug messages.
2272
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273 scsi_debug_*= [SCSI]
2274 See drivers/scsi/scsi_debug.c.
2275
2276 scsi_default_dev_flags=
2277 [SCSI] SCSI default device flags
2278 Format: <integer>
2279
2280 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2281 Format: <vendor>:<model>:<flags>
2282 (flags are integer value)
2283
Randy Dunlap6af66322007-11-14 16:52:25 -08002284 scsi_logging_level= [SCSI] a bit mask of logging levels
2285 See drivers/scsi/scsi_logging.h for bits. Also
2286 settable via sysctl at dev.scsi.logging_level
2287 (/proc/sys/dev/scsi/logging_level).
2288 There is also a nice 'scsi_logging_level' script in the
2289 S390-tools package, available for download at
2290 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002291
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002292 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2293 discovered. async scans them in kernel threads,
2294 allowing boot to proceed. none ignores them, expecting
2295 user space to do the scan.
2296
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002297 security= [SECURITY] Choose a security module to enable at boot.
2298 If this boot parameter is not specified, only the first
2299 security module asking for security registration will be
2300 loaded. An invalid security module name will be treated
2301 as if no module has been chosen.
2302
2303 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 Format: { "0" | "1" }
2305 See security/selinux/Kconfig help text.
2306 0 -- disable.
2307 1 -- enable.
2308 Default value is set via kernel config option.
2309 If enabled at boot time, /selinux/disable can be used
2310 later to disable prior to initial policy load.
2311
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002312 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313
Linus Torvalds1da177e2005-04-16 15:20:36 -07002314 shapers= [NET]
2315 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002316
Yinghai Lub05f78f2008-08-22 01:32:50 -07002317 show_msr= [x86] show boot-time MSR settings
2318 Format: { <integer> }
2319 Show boot-time (BIOS-initialized) MSR settings.
2320 The parameter means the number of CPUs to show,
2321 for example 1 means boot CPU only.
2322
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323 sim710= [SCSI,HW]
2324 See header of drivers/scsi/sim710.c.
2325
2326 simeth= [IA-64]
2327 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002328
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329 slram= [HW,MTD]
2330
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002331 slub_debug[=options[,slabs]] [MM, SLUB]
2332 Enabling slub_debug allows one to determine the
2333 culprit if slab objects become corrupted. Enabling
2334 slub_debug can create guard zones around objects and
2335 may poison objects when not in use. Also tracks the
2336 last alloc / free. For more information see
2337 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002338
2339 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002340 Determines the maximum allowed order for slabs.
2341 A high setting may cause OOMs due to memory
2342 fragmentation. For more information see
2343 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002344
2345 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002346 The minimum number of objects per slab. SLUB will
2347 increase the slab order up to slub_max_order to
2348 generate a sufficiently large slab able to contain
2349 the number of objects indicated. The higher the number
2350 of objects the smaller the overhead of tracking slabs
2351 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002352 For more information see Documentation/vm/slub.txt.
2353
2354 slub_min_order= [MM, SLUB]
2355 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002356 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002357 For more information see Documentation/vm/slub.txt.
2358
2359 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002360 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002361 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002362 allocs to different slabs. Debug options disable
2363 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002364 For more information see Documentation/vm/slub.txt.
2365
Linus Torvalds1da177e2005-04-16 15:20:36 -07002366 smart2= [HW]
2367 Format: <io1>[,<io2>[,...,<io8>]]
2368
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002369 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002370 attempt to substitute SMP alternatives once at boot.
2371
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002372 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2373 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2374 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2375 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2376 smsc-ircc2.ircc_irq= [HW] IRQ line
2377 smsc-ircc2.ircc_dma= [HW] DMA channel
2378 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2379 0: Toshiba Satellite 1800 (GP data pin select)
2380 1: Fast pin select (default)
2381 2: ATC IRMode
2382
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383 snd-ad1816a= [HW,ALSA]
2384
2385 snd-ad1848= [HW,ALSA]
2386
2387 snd-ali5451= [HW,ALSA]
2388
2389 snd-als100= [HW,ALSA]
2390
2391 snd-als4000= [HW,ALSA]
2392
2393 snd-azt2320= [HW,ALSA]
2394
2395 snd-cmi8330= [HW,ALSA]
2396
2397 snd-cmipci= [HW,ALSA]
2398
2399 snd-cs4231= [HW,ALSA]
2400
2401 snd-cs4232= [HW,ALSA]
2402
2403 snd-cs4236= [HW,ALSA]
2404
2405 snd-cs4281= [HW,ALSA]
2406
2407 snd-cs46xx= [HW,ALSA]
2408
2409 snd-dt019x= [HW,ALSA]
2410
2411 snd-dummy= [HW,ALSA]
2412
2413 snd-emu10k1= [HW,ALSA]
2414
2415 snd-ens1370= [HW,ALSA]
2416
2417 snd-ens1371= [HW,ALSA]
2418
2419 snd-es968= [HW,ALSA]
2420
2421 snd-es1688= [HW,ALSA]
2422
2423 snd-es18xx= [HW,ALSA]
2424
2425 snd-es1938= [HW,ALSA]
2426
2427 snd-es1968= [HW,ALSA]
2428
2429 snd-fm801= [HW,ALSA]
2430
2431 snd-gusclassic= [HW,ALSA]
2432
2433 snd-gusextreme= [HW,ALSA]
2434
2435 snd-gusmax= [HW,ALSA]
2436
2437 snd-hdsp= [HW,ALSA]
2438
2439 snd-ice1712= [HW,ALSA]
2440
2441 snd-intel8x0= [HW,ALSA]
2442
2443 snd-interwave= [HW,ALSA]
2444
2445 snd-interwave-stb=
2446 [HW,ALSA]
2447
2448 snd-korg1212= [HW,ALSA]
2449
2450 snd-maestro3= [HW,ALSA]
2451
2452 snd-mpu401= [HW,ALSA]
2453
2454 snd-mtpav= [HW,ALSA]
2455
2456 snd-nm256= [HW,ALSA]
2457
2458 snd-opl3sa2= [HW,ALSA]
2459
2460 snd-opti92x-ad1848=
2461 [HW,ALSA]
2462
2463 snd-opti92x-cs4231=
2464 [HW,ALSA]
2465
2466 snd-opti93x= [HW,ALSA]
2467
2468 snd-pmac= [HW,ALSA]
2469
2470 snd-rme32= [HW,ALSA]
2471
2472 snd-rme96= [HW,ALSA]
2473
2474 snd-rme9652= [HW,ALSA]
2475
2476 snd-sb8= [HW,ALSA]
2477
2478 snd-sb16= [HW,ALSA]
2479
2480 snd-sbawe= [HW,ALSA]
2481
2482 snd-serial= [HW,ALSA]
2483
2484 snd-sgalaxy= [HW,ALSA]
2485
2486 snd-sonicvibes= [HW,ALSA]
2487
2488 snd-sun-amd7930=
2489 [HW,ALSA]
2490
2491 snd-sun-cs4231= [HW,ALSA]
2492
2493 snd-trident= [HW,ALSA]
2494
2495 snd-usb-audio= [HW,ALSA,USB]
2496
2497 snd-via82xx= [HW,ALSA]
2498
2499 snd-virmidi= [HW,ALSA]
2500
2501 snd-wavefront= [HW,ALSA]
2502
2503 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002504
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002505 softlockup_panic=
2506 [KNL] Should the soft-lockup detector generate panics.
2507
Linus Torvalds1da177e2005-04-16 15:20:36 -07002508 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2509 See Documentation/sonypi.txt
2510
2511 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002512 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513
2514 spia_io_base= [HW,MTD]
2515 spia_fio_base=
2516 spia_pedr=
2517 spia_peddr=
2518
2519 sscape= [HW,OSS]
2520 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002521
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2523 See Documentation/scsi/st.txt.
2524
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002525 stacktrace [FTRACE]
2526 Enabled the stack tracer on boot up.
2527
Linus Torvalds1da177e2005-04-16 15:20:36 -07002528 sti= [PARISC,HW]
2529 Format: <num>
2530 Set the STI (builtin display/keyboard on the HP-PARISC
2531 machines) console (graphic card) which should be used
2532 as the initial boot-console.
2533 See also comment in drivers/video/console/sticore.c.
2534
2535 sti_font= [HW]
2536 See comment in drivers/video/console/sticore.c.
2537
2538 stifb= [HW]
2539 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2540
Trond Myklebustcbf11072009-08-09 15:06:19 -04002541 sunrpc.min_resvport=
2542 sunrpc.max_resvport=
2543 [NFS,SUNRPC]
2544 SunRPC servers often require that client requests
2545 originate from a privileged port (i.e. a port in the
2546 range 0 < portnr < 1024).
2547 An administrator who wishes to reserve some of these
2548 ports for other uses may adjust the range that the
2549 kernel's sunrpc client considers to be privileged
2550 using these two parameters to set the minimum and
2551 maximum port values.
2552
Greg Banks42a7fc42007-03-06 01:42:23 -08002553 sunrpc.pool_mode=
2554 [NFS]
2555 Control how the NFS server code allocates CPUs to
2556 service thread pools. Depending on how many NICs
2557 you have and where their interrupts are bound, this
2558 option will affect which CPUs will do NFS serving.
2559 Note: this parameter cannot be changed while the
2560 NFS server is running.
2561
2562 auto the server chooses an appropriate mode
2563 automatically using heuristics
2564 global a single global pool contains all CPUs
2565 percpu one pool for each CPU
2566 pernode one pool for each NUMA node (equivalent
2567 to global on non-NUMA machines)
2568
Trond Myklebustcbf11072009-08-09 15:06:19 -04002569 sunrpc.tcp_slot_table_entries=
2570 sunrpc.udp_slot_table_entries=
2571 [NFS,SUNRPC]
2572 Sets the upper limit on the number of simultaneous
2573 RPC calls that can be sent from the client to a
2574 server. Increasing these values may allow you to
2575 improve throughput, but will also increase the
2576 amount of memory reserved for use by the client.
2577
Linus Torvalds1da177e2005-04-16 15:20:36 -07002578 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002579
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580 switches= [HW,M68k]
2581
2582 sym53c416= [HW,SCSI]
2583 See header of drivers/scsi/sym53c416.c.
2584
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002585 sysrq_always_enabled
2586 [KNL]
2587 Ignore sysrq setting - this boot parameter will
2588 neutralize any effect of /proc/sys/kernel/sysrq.
2589 Useful for debugging.
2590
Linus Torvalds1da177e2005-04-16 15:20:36 -07002591 t128= [HW,SCSI]
2592 See header of drivers/scsi/t128.c.
2593
2594 tdfx= [HW,DRM]
2595
David Brownell77437fd2008-07-23 21:28:33 -07002596 test_suspend= [SUSPEND]
2597 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2598 standby suspend) as the system sleep state to briefly
2599 enter during system startup. The system is woken from
2600 this state using a wakeup-capable RTC alarm.
2601
Linus Torvalds1da177e2005-04-16 15:20:36 -07002602 thash_entries= [KNL,NET]
2603 Set number of hash buckets for TCP connection
2604
Len Brownf8707ec2007-08-12 00:12:54 -04002605 thermal.act= [HW,ACPI]
2606 -1: disable all active trip points in all thermal zones
2607 <degrees C>: override all lowest active trip points
2608
Len Brownc52a7412007-08-14 15:49:32 -04002609 thermal.crt= [HW,ACPI]
2610 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002611 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002612
Len Brownf5487142007-08-12 00:12:44 -04002613 thermal.nocrt= [HW,ACPI]
2614 Set to disable actions on ACPI thermal zone
2615 critical and hot trip points.
2616
Len Brown72b33ef2007-08-12 00:12:17 -04002617 thermal.off= [HW,ACPI]
2618 1: disable ACPI thermal control
2619
Len Browna70cdc52007-08-12 00:12:35 -04002620 thermal.psv= [HW,ACPI]
2621 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002622 <degrees C>: override all passive trip points to this
2623 value
Len Browna70cdc52007-08-12 00:12:35 -04002624
Len Brown730ff342007-08-12 00:12:26 -04002625 thermal.tzp= [HW,ACPI]
2626 Specify global default ACPI thermal zone polling rate
2627 <deci-seconds>: poll all this frequency
2628 0: no polling (default)
2629
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630 tmscsim= [HW,SCSI]
2631 See comment before function dc390_setup() in
2632 drivers/scsi/tmscsim.c.
2633
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002634 topology= [S390]
2635 Format: {off | on}
2636 Specify if the kernel should make use of the cpu
2637 topology informations if the hardware supports these.
2638 The scheduler will make use of these informations and
2639 e.g. base its process migration decisions on it.
2640 Default is off.
2641
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642 tp720= [HW,PS2]
2643
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002644 tpm_suspend_pcr=[HW,TPM]
2645 Format: integer pcr id
2646 Specify that at suspend time, the tpm driver
2647 should extend the specified pcr with zeros,
2648 as a workaround for some chips which fail to
2649 flush the last written pcr on TPM_SaveState.
2650 This will guarantee that all the other pcrs
2651 are saved.
2652
Li Zefan9d612be2009-06-24 17:33:15 +08002653 trace_buf_size=nn[KMG]
2654 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002655
Li Zefan020e5f82009-07-01 10:47:05 +08002656 trace_event=[event-list]
2657 [FTRACE] Set and start specified trace events in order
2658 to facilitate early boot debugging.
2659 See also Documentation/trace/events.txt
2660
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002662 Format:
2663 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2664
Alok Kataria395628e2008-10-24 17:22:01 -07002665 tsc= Disable clocksource-must-verify flag for TSC.
2666 Format: <string>
2667 [x86] reliable: mark tsc clocksource as reliable, this
2668 disables clocksource verification at runtime.
2669 Used to enable high-resolution timer mode on older
2670 hardware, and in virtualized environment.
2671
Randy Dunlapa9913042005-10-23 12:57:11 -07002672 turbografx.map[2|3]= [HW,JOY]
2673 TurboGraFX parallel port interface
2674 Format:
2675 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002676 See also Documentation/input/joystick-parport.txt
2677
2678 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2679 See header of drivers/scsi/u14-34f.c.
2680
2681 uart401= [HW,OSS]
2682 Format: <io>,<irq>
2683
2684 uart6850= [HW,OSS]
2685 Format: <io>,<irq>
2686
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002687 uhash_entries= [KNL,NET]
2688 Set number of hash buckets for UDP/UDP-Lite connections
2689
Alan Stern5f8364b2006-12-05 16:29:55 -05002690 uhci-hcd.ignore_oc=
2691 [USB] Ignore overcurrent events (default N).
2692 Some badly-designed motherboards generate lots of
2693 bogus events, for ports that aren't wired to
2694 anything. Set this parameter to avoid log spamming.
2695 Note that genuine overcurrent events won't be
2696 reported either.
2697
Simon Arlotte3a61b02008-07-19 23:32:54 +01002698 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302699 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002700 Set unknown_nmi_panic=1 early on boot.
2701
Alan Sternb5e795f2007-02-20 15:00:53 -05002702 usbcore.autosuspend=
2703 [USB] The autosuspend time delay (in seconds) used
2704 for newly-detected USB devices (default 2). This
2705 is the time required before an idle device will be
2706 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002707 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002708
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002709 usbcore.usbfs_snoop=
2710 [USB] Set to log all usbfs traffic (default 0 = off).
2711
2712 usbcore.blinkenlights=
2713 [USB] Set to cycle leds on hubs (default 0 = off).
2714
2715 usbcore.old_scheme_first=
2716 [USB] Start with the old device initialization
2717 scheme (default 0 = off).
2718
2719 usbcore.use_both_schemes=
2720 [USB] Try the other device initialization scheme
2721 if the first one fails (default 1 = enabled).
2722
2723 usbcore.initial_descriptor_timeout=
2724 [USB] Specifies timeout for the initial 64-byte
2725 USB_REQ_GET_DESCRIPTOR request in milliseconds
2726 (default 5000 = 5.0 seconds).
2727
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728 usbhid.mousepoll=
2729 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002730
Alan Sternd4f373e2008-11-10 14:07:45 -05002731 usb-storage.delay_use=
2732 [UMS] The delay in seconds before a new device is
2733 scanned for Logical Units (default 5).
2734
2735 usb-storage.quirks=
2736 [UMS] A list of quirks entries to supplement or
2737 override the built-in unusual_devs list. List
2738 entries are separated by commas. Each entry has
2739 the form VID:PID:Flags where VID and PID are Vendor
2740 and Product ID values (4-digit hex numbers) and
2741 Flags is a set of characters, each corresponding
2742 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002743 a = SANE_SENSE (collect more than 18 bytes
2744 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002745 b = BAD_SENSE (don't collect more than 18
2746 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002747 c = FIX_CAPACITY (decrease the reported
2748 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002749 h = CAPACITY_HEURISTICS (decrease the
2750 reported device capacity by one
2751 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002752 i = IGNORE_DEVICE (don't bind to this
2753 device);
2754 l = NOT_LOCKABLE (don't try to lock and
2755 unlock ejectable media);
2756 m = MAX_SECTORS_64 (don't transfer more
2757 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002758 o = CAPACITY_OK (accept the capacity
2759 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002760 r = IGNORE_RESIDUE (the device reports
2761 bogus residue values);
2762 s = SINGLE_LUN (the device has only one
2763 Logical Unit);
2764 w = NO_WP_DETECT (don't test whether the
2765 medium is write-protected).
2766 Example: quirks=0419:aaf5:rl,0421:0433:rc
2767
Ian Campbell14315592010-02-17 10:38:10 +00002768 userpte=
2769 [X86] Flags controlling user PTE allocations.
2770
2771 nohigh = do not allocate PTE pages in
2772 HIGHMEM regardless of setting
2773 of CONFIG_HIGHPTE.
2774
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302775 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002776 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002777 vdso=1: enable VDSO (default)
2778 vdso=0: disable VDSO mapping
2779
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302780 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002781 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2782 vdso32=1: enable 32-bit VDSO (default)
2783 vdso32=0: disable 32-bit VDSO mapping
2784
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002785 vector= [IA-64,SMP]
2786 vector=percpu: enable percpu vector domain
2787
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788 video= [FB] Frame buffer configuration
2789 See Documentation/fb/modedb.txt.
2790
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002791 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002792 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002793 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002794 Use vga=ask for menu.
2795 This is actually a boot loader parameter; the value is
2796 passed to the kernel using a special protocol.
2797
Randy Dunlapa9913042005-10-23 12:57:11 -07002798 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799 size of <nn>. This can be used to increase the
2800 minimum size (128MB on x86). It can also be used to
2801 decrease the size and leave more room for directly
2802 mapped kernel RAM.
2803
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002804 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2805 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002806
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002807 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2808 Format: <command>
2809
2810 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2811 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002812
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002813 vt.cur_default= [VT] Default cursor shape.
2814 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2815 the parameters of the <Esc>[?A;B;Cc escape sequence;
2816 see VGA-softcursor.txt. Default: 2 = underline.
2817
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002818 vt.default_blu= [VT]
2819 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2820 Change the default blue palette of the console.
2821 This is a 16-member array composed of values
2822 ranging from 0-255.
2823
2824 vt.default_grn= [VT]
2825 Format: <green0>,<green1>,<green2>,...,<green15>
2826 Change the default green palette of the console.
2827 This is a 16-member array composed of values
2828 ranging from 0-255.
2829
2830 vt.default_red= [VT]
2831 Format: <red0>,<red1>,<red2>,...,<red15>
2832 Change the default red palette of the console.
2833 This is a 16-member array composed of values
2834 ranging from 0-255.
2835
2836 vt.default_utf8=
2837 [VT]
2838 Format=<0|1>
2839 Set system-wide default UTF-8 mode for all tty's.
2840 Default is 1, i.e. UTF-8 mode is enabled for all
2841 newly opened terminals.
2842
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002843 vt.global_cursor_default=
2844 [VT]
2845 Format=<-1|0|1>
2846 Set system-wide default for whether a cursor
2847 is shown on new VTs. Default is -1,
2848 i.e. cursors will be created by default unless
2849 overridden by individual drivers. 0 will hide
2850 cursors, 1 will display them.
2851
Linus Torvalds1da177e2005-04-16 15:20:36 -07002852 waveartist= [HW,OSS]
2853 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002854
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855 wd33c93= [HW,SCSI]
2856 See header of drivers/scsi/wd33c93.c.
2857
2858 wd7000= [HW,SCSI]
2859 See header of drivers/scsi/wd7000.c.
2860
Randy Dunlap4724ba572010-05-03 11:42:52 -07002861 watchdog timers [HW,WDT] For information on watchdog timers,
2862 see Documentation/watchdog/watchdog-parameters.txt
2863 or other driver-specific files in the
2864 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002866 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2867 default x2apic cluster mode on platforms
2868 supporting x2apic.
2869
Jacob Panbb24c472009-09-02 07:37:17 -07002870 x86_mrst_timer= [X86-32,APBT]
2871 Choose timer option for x86 Moorestown MID platform.
2872 Two valid options are apbt timer only and lapic timer
2873 plus one apbt timer for broadcast timer.
2874 x86_mrst_timer=apbt_only | lapic_and_apbt
2875
Linus Torvalds1da177e2005-04-16 15:20:36 -07002876 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2877 xd_geo= See header of drivers/block/xd.c.
2878
2879 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002880 Format:
2881 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882
Randy Dunlapa9913042005-10-23 12:57:11 -07002883______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002884
2885TODO:
2886
2887 Add documentation for ALSA options.
2888 Add more DRM drivers.