blob: 0afdd284d656e05661fea05d347a57dc11a69f9d [file] [log] [blame]
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).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200257 nonvs prevents the kernel from saving/restoring the
258 ACPI NVS memory during suspend/hibernation and resume.
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 Zohar3323eec92009-02-04 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 Zohar3323eec92009-02-04 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
Chris Wrightd1423d52010-07-20 11:06:49 -07001031 intremap= [X86-64, Intel-IOMMU]
1032 Format: { on (default) | off | nosid }
1033 on enable Interrupt Remapping (default)
1034 off disable Interrupt Remapping
1035 nosid disable Source ID checking
1036
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001037 inttest= [IA64]
1038
1039 iomem= Disable strict checking of access to MMIO memory
1040 strict regions from userspace.
1041 relaxed
1042
1043 iommu= [x86]
1044 off
1045 force
1046 noforce
1047 biomerge
1048 panic
1049 nopanic
1050 merge
1051 nomerge
1052 forcesac
1053 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001054 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001055
1056 io7= [HW] IO7 for Marvel based alpha systems
1057 See comment before marvel_specify_io7 in
1058 arch/alpha/kernel/core_marvel.c.
1059
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301060 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001061 0x80
1062 Standard port 0x80 based delay
1063 0xed
1064 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001065 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001066 Simple two microseconds delay
1067 none
1068 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001069
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001071 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072
1073 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001074 See comment before ip2_setup() in
1075 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076
1077 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1078 See header of drivers/scsi/ips.c.
1079
Alan Cox200803d2005-06-28 20:45:18 -07001080 irqfixup [HW]
1081 When an interrupt is not handled search all handlers
1082 for it. Intended to get systems with badly broken
1083 firmware running.
1084
1085 irqpoll [HW]
1086 When an interrupt is not handled search all handlers
1087 for it. Also check all handlers each timer
1088 interrupt. Intended to get systems with badly broken
1089 firmware running.
1090
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001092 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093
1094 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001095 Format:
1096 <cpu number>,...,<cpu number>
1097 or
Li Zefanb225d442008-11-06 12:53:39 -08001098 <cpu number>-<cpu number>
1099 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001100 or a mixture
1101 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001102
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 This option can be used to specify one or more CPUs
1104 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001105 algorithms. You can move a process onto or off an
1106 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 <cpu number> begins at 0 and the maximum value is
1108 "number of CPUs in system - 1".
1109
1110 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001111 alternative -- manually setting the CPU mask of all
1112 tasks in the system -- can cause problems and
1113 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Randy Dunlapa9913042005-10-23 12:57:11 -07001115 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
1117 js= [HW,JOY] Analog joystick
1118 See Documentation/input/joystick.txt.
1119
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001120 keepinitrd [HW,ARM]
1121
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301122 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001123 specifies the amount of memory usable by the kernel
1124 for non-movable allocations. The requested amount is
1125 spread evenly throughout all nodes in the system. The
1126 remaining memory in each node is used for Movable
1127 pages. In the event, a node is too small to have both
1128 kernelcore and Movable pages, kernelcore pages will
1129 take priority and other nodes will have a larger number
1130 of kernelcore pages. The Movable zone is used for the
1131 allocation of pages that may be reclaimed or moved
1132 by the page migration subsystem. This means that
1133 HugeTLB pages may not be allocated from this zone.
1134 Note that allocations like PTEs-from-HighMem still
1135 use the HighMem zone if it exists, and the Normal
1136 zone if it does not.
1137
Jason Wessel4fe1da42010-05-20 21:04:31 -05001138 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1139 Format: <Controller#>[,poll interval]
1140 The controller # is the number of the ehci usb debug
1141 port as it is probed via PCI. The poll interval is
1142 optional and is the number seconds in between
1143 each poll cycle to the debug port in case you need
1144 the functionality for interrupting the kernel with
1145 gdb or control-c on the dbgp connection. When
1146 not using this parameter you use sysrq-g to break into
1147 the kernel debugger.
1148
Jason Wessel84c08fd2010-05-20 21:04:24 -05001149 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001150 Requires a tty driver that supports console polling,
1151 or a supported polling keyboard driver (non-usb).
1152 Serial only format: <serial_device>[,baud]
1153 keyboard only format: kbd
1154 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001155
Jason Wessel84c08fd2010-05-20 21:04:24 -05001156 kgdbwait [KGDB] Stop kernel execution and enter the
1157 kernel debugger at the earliest opportunity.
1158
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001159 kmac= [MIPS] korina ethernet MAC address.
1160 Configure the RouterBoard 532 series on-chip
1161 Ethernet adapter MAC address.
1162
Catalin Marinas04f70332009-06-11 13:22:39 +01001163 kmemleak= [KNL] Boot-time kmemleak enable/disable
1164 Valid arguments: on, off
1165 Default: on
1166
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301167 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001168 in oops dumps.
1169
Andre Przywarafef07aa2009-07-10 14:20:35 +02001170 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1171 Default is 0 (don't ignore, but inject #GP)
1172
1173 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1174 Default is 1 (enabled)
1175
1176 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1177 Default is 0 (off)
1178
1179 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1180 for all guests.
1181 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1182
1183 kvm-intel.bypass_guest_pf=
1184 [KVM,Intel] Disables bypassing of guest page faults
1185 on Intel chips. Default is 1 (enabled)
1186
1187 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1188 (virtualized MMU) support on capable Intel chips.
1189 Default is 1 (enabled)
1190
1191 kvm-intel.emulate_invalid_guest_state=
1192 [KVM,Intel] Enable emulation of invalid guest states
1193 Default is 0 (disabled)
1194
1195 kvm-intel.flexpriority=
1196 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1197 Default is 1 (enabled)
1198
1199 kvm-intel.unrestricted_guest=
1200 [KVM,Intel] Disable unrestricted guest feature
1201 (virtualized real and unpaged mode) on capable
1202 Intel chips. Default is 1 (enabled)
1203
1204 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1205 feature (tagged TLBs) on capable Intel chips.
1206 Default is 1 (enabled)
1207
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208 l2cr= [PPC]
1209
Robert Brosea78bfbf2008-03-29 07:20:23 +11001210 l3cr= [PPC]
1211
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001212 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001213 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301215 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001216 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001217
FD Camifcb71f62008-01-06 19:08:56 +01001218 libata.dma= [LIBATA] DMA control
1219 libata.dma=0 Disable all PATA and SATA DMA
1220 libata.dma=1 PATA and SATA Disk DMA only
1221 libata.dma=2 ATAPI (CDROM) DMA only
1222 libata.dma=4 Compact Flash DMA only
1223 Combinations also work, so libata.dma=3 enables DMA
1224 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001225
1226 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1227 libata.ignore_hpa=0 keep BIOS limits (default)
1228 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001229
Dave Jones78e70c22007-09-27 11:50:13 -04001230 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1231 when set.
1232 Format: <int>
1233
Tejun Heo33267322008-02-13 09:15:09 +09001234 libata.force= [LIBATA] Force configurations. The format is comma
1235 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001236 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001237 matching port, link or device. Basically, it matches
1238 the ATA ID string printed on console by libata. If
1239 the whole ID part is omitted, the last PORT and DEVICE
1240 values are used. If ID hasn't been specified yet, the
1241 configuration applies to all ports, links and devices.
1242
1243 If only DEVICE is omitted, the parameter applies to
1244 the port and all links and devices behind it. DEVICE
1245 number of 0 either selects the first device or the
1246 first fan-out link behind PMP device. It does not
1247 select the host link. DEVICE number of 15 selects the
1248 host link and device attached to it.
1249
1250 The VAL specifies the configuration to force. As long
1251 as there's no ambiguity shortcut notation is allowed.
1252 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1253 The following configurations can be forced.
1254
1255 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1256 Any ID with matching PORT is used.
1257
1258 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1259
1260 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1261 udma[/][16,25,33,44,66,100,133] notation is also
1262 allowed.
1263
1264 * [no]ncq: Turn on or off NCQ.
1265
Tejun Heo05944bd2008-08-13 20:19:09 +09001266 * nohrst, nosrst, norst: suppress hard, soft
1267 and both resets.
1268
Tejun Heo43c9c592010-05-23 12:59:11 +02001269 * dump_id: dump IDENTIFY data.
1270
Tejun Heo33267322008-02-13 09:15:09 +09001271 If there are multiple matching configurations changing
1272 the same attribute, the last one is used.
1273
Yinghai Lu95f72d12010-07-12 14:36:09 +10001274 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001275
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001277 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001279 lockd.nlm_grace_period=P [NFS] Assign grace period.
1280 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001282 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1283 Format: <integer>
1284
1285 lockd.nlm_timeout=T [NFS] Assign timeout value.
1286 Format: <integer>
1287
1288 lockd.nlm_udpport=M [NFS] Assign UDP port.
1289 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290
1291 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1292 Format: <irq>
1293
1294 loglevel= All Kernel Messages with a loglevel smaller than the
1295 console loglevel will be printed to the console. It can
1296 also be changed with klogd or other programs. The
1297 loglevels are defined as follows:
1298
1299 0 (KERN_EMERG) system is unusable
1300 1 (KERN_ALERT) action must be taken immediately
1301 2 (KERN_CRIT) critical conditions
1302 3 (KERN_ERR) error conditions
1303 4 (KERN_WARNING) warning conditions
1304 5 (KERN_NOTICE) normal but significant condition
1305 6 (KERN_INFO) informational
1306 7 (KERN_DEBUG) debug-level messages
1307
1308 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001309 Format: { n | nk | nM }
1310 n must be a power of two. The default size
1311 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312
Randy Dunlapaccaa242007-10-16 01:29:37 -07001313 logo.nologo [FB] Disables display of the built-in Linux logo.
1314 This may be used to provide more screen space for
1315 kernel log messages and is useful when debugging
1316 kernel boot problems.
1317
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318 lp=0 [LP] Specify parallel ports to use, e.g,
1319 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1320 lp=reset first parallel port). 'lp=0' disables the
1321 lp=auto printer driver. 'lp=reset' (which can be
1322 specified in addition to the ports) causes
1323 attached printers to be reset. Using
1324 lp=port1,port2,... specifies the parallel ports
1325 to associate lp devices with, starting with
1326 lp0. A port specification may be 'none' to skip
1327 that lp device, or a parport name such as
1328 'parport0'. Specifying 'lp=auto' instead of a
1329 port specification list means that device IDs
1330 from each port should be examined, to see if
1331 an IEEE 1284-compliant printer is attached; if
1332 so, the driver will manage that printer.
1333 See also header of drivers/char/lp.c.
1334
1335 lpj=n [KNL]
1336 Sets loops_per_jiffy to given constant, thus avoiding
1337 time-consuming boot-time autodetection (up to 250 ms per
1338 CPU). 0 enables autodetection (default). To determine
1339 the correct value for your kernel, boot with normal
1340 autodetection and see what value is printed. Note that
1341 on SMP systems the preset will be applied to all CPUs,
1342 which is likely to cause problems if your CPUs need
1343 significantly divergent settings. An incorrect value
1344 will cause delays in the kernel to be wrong, leading to
1345 unpredictable I/O errors and other breakage. Although
1346 unlikely, in the extreme case this might damage your
1347 hardware.
1348
1349 ltpc= [NET]
1350 Format: <io>,<irq>,<dma>
1351
Randy Dunlapa9913042005-10-23 12:57:11 -07001352 mac5380= [HW,SCSI] Format:
1353 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354
Randy Dunlapa9913042005-10-23 12:57:11 -07001355 machvec= [IA64] Force the use of a particular machine-vector
1356 (machvec) in a generic kernel.
1357 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
Wu Zhangjin3209e702009-07-02 23:27:12 +08001359 machtype= [Loongson] Share the same kernel image file between different
1360 yeeloong laptop.
1361 Example: machtype=lemote-yeeloong-2f-7inch
1362
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001363 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1364 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
1366 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001367 should make use of. maxcpus=n : n >= 0 limits the
1368 kernel to using 'n' processors. n=0 is a special case,
1369 it is equivalent to "nosmp", which also disables
1370 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001372 max_loop= [LOOP] Maximum number of loopback devices that can
1373 be mounted
1374 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001375
Randy Dunlapa9913042005-10-23 12:57:11 -07001376 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 Should be between 1 and 2^32-1.
1378
1379 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001380 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 Should be between 1 and 16384.
1382
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 mcatest= [IA-64]
1384
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001385 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386
Uwe Hermann71cced62008-10-20 09:32:21 -07001387 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001388
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 md= [HW] RAID subsystems devices and level
1390 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001391
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 mdacon= [MDA]
1393 Format: <first>,<last>
1394 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001395
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1397 Amount of memory to be used when the kernel is not able
1398 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001399 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 address space collisions. Without memmap= PCI devices
1401 could be placed at addresses belonging to unused RAM.
1402
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001403 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 memory.
1405
Paul Mundt6902aa82008-09-21 17:14:42 +09001406 memchunk=nn[KMG]
1407 [KNL,SH] Allow user to override the default size for
1408 per-device physically contiguous DMA buffers.
1409
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301410 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 E820 memory map, as specified by the user.
1412 Such memmap=exactmap lines can be constructed based on
1413 BIOS output or other requirements. See the memmap=nn@ss
1414 option description.
1415
1416 memmap=nn[KMG]@ss[KMG]
1417 [KNL] Force usage of a specific region of memory
1418 Region of memory to be used, from ss to ss+nn.
1419
1420 memmap=nn[KMG]#ss[KMG]
1421 [KNL,ACPI] Mark specific memory as ACPI data.
1422 Region of memory to be used, from ss to ss+nn.
1423
1424 memmap=nn[KMG]$ss[KMG]
1425 [KNL,ACPI] Mark specific memory as reserved.
1426 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001427 Example: Exclude memory from 0x18690000-0x1869ffff
1428 memmap=64K$0x18690000
1429 or
1430 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001432 memory_corruption_check=0/1 [X86]
1433 Some BIOSes seem to corrupt the first 64k of
1434 memory when doing things like suspend/resume.
1435 Setting this option will scan the memory
1436 looking for corruption. Enabling this will
1437 both detect corruption and prevent the kernel
1438 from using the memory being corrupted.
1439 However, its intended as a diagnostic tool; if
1440 repeatable BIOS-originated corruption always
1441 affects the same memory, you can use memmap=
1442 to prevent the kernel from using that memory.
1443
1444 memory_corruption_check_size=size [X86]
1445 By default it checks for corruption in the low
1446 64k, making this memory unavailable for normal
1447 use. Use this parameter to scan for
1448 corruption in more or less memory.
1449
1450 memory_corruption_check_period=seconds [X86]
1451 By default it checks for corruption every 60
1452 seconds. Use this parameter to check at some
1453 other rate. 0 disables periodic checking.
1454
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001455 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001456 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001457 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001458 Specifies the number of memtest passes to be
1459 performed. Each pass selects another test
1460 pattern from a given set of patterns. Memtest
1461 fills the memory with this pattern, validates
1462 memory contents and reserves bad memory
1463 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001464
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 meye.*= [HW] Set MotionEye Camera parameters
1466 See Documentation/video4linux/meye.txt.
1467
Andres Salomon8f368812007-10-12 23:04:06 +02001468 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1469 Multi-Function General Purpose Timers on AMD Geode
1470 platforms.
1471
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001472 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1473 the BIOS has incorrectly applied a workaround. TinyBIOS
1474 version 0.98 is known to be affected, 0.99 fixes the
1475 problem by letting the user disable the workaround.
1476
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 mga= [HW,DRM]
1478
Randy Dunlap1c207f92008-11-19 15:36:16 -08001479 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1480 physical address is ignored.
1481
Michel Pollet39f45d72009-05-20 11:10:31 +01001482 mini2440= [ARM,HW,KNL]
1483 Format:[0..2][b][c][t]
1484 Default: "0tb"
1485 MINI2440 configuration specification:
1486 0 - The attached screen is the 3.5" TFT
1487 1 - The attached screen is the 7" TFT
1488 2 - The VGA Shield is attached (1024x768)
1489 Leaving out the screen size parameter will not load
1490 the TFT driver, and the framebuffer will be left
1491 unconfigured.
1492 b - Enable backlight. The TFT backlight pin will be
1493 linked to the kernel VESA blanking code and a GPIO
1494 LED. This parameter is not necessary when using the
1495 VGA shield.
1496 c - Enable the s3c camera interface.
1497 t - Reserved for enabling touchscreen support. The
1498 touchscreen support is not enabled in the mainstream
1499 kernel as of 2.6.30, a preliminary port can be found
1500 in the "bleeding edge" mini2440 support kernel at
1501 http://repo.or.cz/w/linux-2.6/mini2440.git
1502
Mel Gorman6b74ab92008-07-23 21:26:49 -07001503 mminit_loglevel=
1504 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1505 parameter allows control of the logging verbosity for
1506 the additional memory initialisation checks. A value
1507 of 0 disables mminit logging and a level of 4 will
1508 log everything. Information is printed at KERN_DEBUG
1509 so loglevel=8 may also need to be specified.
1510
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 mousedev.tap_time=
1512 [MOUSE] Maximum time between finger touching and
1513 leaving touchpad surface for touch to be considered
1514 a tap and be reported as a left button click (for
1515 touchpads working in absolute mode only).
1516 Format: <msecs>
1517 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1518 reporting absolute coordinates, such as tablets
1519 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1520 reporting absolute coordinates, such as tablets
1521
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301522 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001523 is similar to kernelcore except it specifies the
1524 amount of memory used for migratable allocations.
1525 If both kernelcore and movablecore is specified,
1526 then kernelcore will be at *least* the specified
1527 value but may be more. If movablecore on its own
1528 is specified, the administrator must be careful
1529 that the amount of memory usable for all allocations
1530 is not too small.
1531
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532 mpu401= [HW,OSS]
1533 Format: <io>,<irq>
1534
1535 MTD_Partition= [MTD]
1536 Format: <name>,<region-number>,<size>,<offset>
1537
Randy Dunlapa9913042005-10-23 12:57:11 -07001538 MTD_Region= [MTD] Format:
1539 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540
1541 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001542 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001544 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1545
1546 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1547
1548 boundary - index of last SLC block on Flex-OneNAND.
1549 The remaining blocks are configured as MLC blocks.
1550 lock - Configure if Flex-OneNAND boundary should be locked.
1551 Once locked, the boundary cannot be changed.
1552 1 indicates lock status, 0 indicates unlock status.
1553
Ben Dooks9db829f2008-07-03 11:24:29 +01001554 mtdset= [ARM]
1555 ARM/S3C2412 JIVE boot control
1556
1557 See arch/arm/mach-s3c2412/mach-jive.c
1558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001560 [HW] Make the MicroTouch USB driver use raw coordinates
1561 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001563 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001564 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001565 that could hold holes aka. UC entries.
1566
1567 mtrr_gran_size=nn[KMG] [X86]
1568 Used for mtrr cleanup. It is granularity of mtrr block.
1569 Default is 1.
1570 Large value could prevent small alignment from
1571 using up MTRRs.
1572
1573 mtrr_spare_reg_nr=n [X86]
1574 Format: <integer>
1575 Range: 0,7 : spare reg number
1576 Default : 1
1577 Used for mtrr cleanup. It is spare mtrr entries number.
1578 Set to 2 or more if your graphical card needs more.
1579
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1581
1582 NCR_D700= [HW,SCSI]
1583 See header of drivers/scsi/NCR_D700.c.
1584
1585 ncr5380= [HW,SCSI]
1586
1587 ncr53c400= [HW,SCSI]
1588
1589 ncr53c400a= [HW,SCSI]
1590
1591 ncr53c406a= [HW,SCSI]
1592
1593 ncr53c8xx= [HW,SCSI]
1594
1595 netdev= [NET] Network devices parameters
1596 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1597 Note that mem_start is often overloaded to mean
1598 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001599 This usage is only documented in each driver source
1600 file if at all.
1601
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001602 nf_conntrack.acct=
1603 [NETFILTER] Enable connection tracking flow accounting
1604 0 to disable accounting
1605 1 to enable accounting
1606 Default value depends on CONFIG_NF_CT_ACCT that is
1607 going to be removed in 2.6.29.
1608
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001610 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611
1612 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001613 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614
Trond Myklebusta72b4422006-01-03 09:55:41 +01001615 nfs.callback_tcpport=
1616 [NFS] set the TCP port on which the NFSv4 callback
1617 channel should listen.
1618
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001619 nfs.cache_getent=
1620 [NFS] sets the pathname to the program which is used
1621 to update the NFS client cache entries.
1622
1623 nfs.cache_getent_timeout=
1624 [NFS] sets the timeout after which an attempt to
1625 update a cache entry is deemed to have failed.
1626
Trond Myklebust58df0952006-01-03 09:55:57 +01001627 nfs.idmap_cache_timeout=
1628 [NFS] set the maximum lifetime for idmapper cache
1629 entries.
1630
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001631 nfs.enable_ino64=
1632 [NFS] enable 64-bit inode numbers.
1633 If zero, the NFS client will fake up a 32-bit inode
1634 number for the readdir() and stat() syscalls instead
1635 of returning the full 64-bit number.
1636 The default is to return 64-bit inode numbers.
1637
Paul Mundt1e1030d2009-09-01 17:38:32 +09001638 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001639 when a NMI is triggered.
1640 Format: [state][,regs][,debounce][,die]
1641
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301642 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001643 Format: [panic,][num]
1644 Valid num: 0,1,2
1645 0 - turn nmi_watchdog off
1646 1 - use the IO-APIC timer for the NMI watchdog
1647 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001648 a performance counter. Note: This will use one
1649 performance counter and the local APIC's performance
1650 vector.
1651 When panic is specified, panic when an NMI watchdog
1652 timeout occurs.
1653 This is useful when you use a panic=... timeout and
1654 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001655 Instead of 1 and 2 it is possible to use the following
1656 symbolic names: lapic and ioapic
1657 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658
Anton Vorontsovbff38772009-07-08 11:10:56 -07001659 netpoll.carrier_timeout=
1660 [NET] Specifies amount of time (in seconds) that
1661 netpoll should wait for a carrier. By default netpoll
1662 waits 4 seconds.
1663
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001664 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 emulation library even if a 387 maths coprocessor
1666 is present.
1667
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001668 no_console_suspend
1669 [HW] Never suspend the console
1670 Disable suspending of consoles during suspend and
1671 hibernate operations. Once disabled, debugging
1672 messages can reach various consoles while the rest
1673 of the system is being put to sleep (ie, while
1674 debugging driver suspend/resume hooks). This may
1675 not work reliably with all consoles, but is known
1676 to work with serial and VGA consoles.
1677
Christoph Lameterc1aee212007-05-31 00:40:47 -07001678 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1679 caches in the slab allocator. Saves per-node memory,
1680 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001681
Randy Dunlapa9913042005-10-23 12:57:11 -07001682 noalign [KNL,ARM]
1683
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684 noapic [SMP,APIC] Tells the kernel to not make use of any
1685 IOAPICs that may be present in the system.
1686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 nobats [PPC] Do not use BATs for mapping kernel lowmem
1688 on "Classic" PPC cores.
1689
1690 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001691
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001692 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1693
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001694 nodelayacct [KNL] Disable per-task delay accounting
1695
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1697
Paul Mundt6902aa82008-09-21 17:14:42 +09001698 nodsp [SH] Disable hardware DSP at boot time.
1699
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301700 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001701
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 noexec [IA-64]
1703
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301704 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001705 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001707 noexec=off: disable non-executable mappings
1708
1709 noexec32 [X86-64]
1710 This affects only 32-bit executables.
1711 noexec32=on: enable non-executable mappings (default)
1712 read doesn't imply executable mappings
1713 noexec32=off: disable non-executable mappings
1714 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715
Paul Mundt6902aa82008-09-21 17:14:42 +09001716 nofpu [SH] Disable hardware FPU at boot time.
1717
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001718 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001719 register save and restore. The kernel will only save
1720 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
Suresh Siddha0c752a92009-05-22 12:17:45 -07001722 noxsave [BUGS=X86] Disables x86 extended register state save
1723 and restore using xsave. The kernel will fallback to
1724 enabling legacy floating-point and sse state.
1725
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001726 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1727 wfi(ARM) instruction doesn't work correctly and not to
1728 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001729
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001730 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 instruction doesn't work correctly and not to
1732 use it.
1733
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001734 no_file_caps Tells the kernel not to honor file capabilities. The
1735 only way then for a file to be executed with privilege
1736 is to be setuid root or executed by root.
1737
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738 nohalt [IA-64] Tells the kernel not to use the power saving
1739 function PAL_HALT_LIGHT when idle. This increases
1740 power-consumption. On the positive side, it reduces
1741 interrupt wake-up latency, which may improve performance
1742 in certain environments such as networked servers or
1743 real-time systems.
1744
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001745 nohz= [KNL] Boottime enable/disable dynamic ticks
1746 Valid arguments: on, off
1747 Default: on
1748
Paul Mundteeee7852009-04-02 12:31:16 +09001749 noiotrap [SH] Disables trapped I/O port accesses.
1750
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001751 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752 disable unhandled interrupt sources.
1753
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301754 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001755 broken timer IRQ sources.
1756
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 noisapnp [ISAPNP] Disables ISA PnP code.
1758
1759 noinitrd [RAM] Tells the kernel not to load any configured
1760 initial RAM disk.
1761
Weidong Han03ea8152009-04-17 16:42:15 +08001762 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1763 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001764 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001765
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 nointroute [IA-64]
1767
Tony Luck0aa366f2007-07-20 11:22:30 -07001768 nojitter [IA64] Disables jitter checking for ITC timers.
1769
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001770 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001772 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001773
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 noltlbs [PPC] Do not use large page/tlb entries for kernel
1775 lowmem mapping on PPC40x.
1776
Horms312f1f02006-02-22 09:57:55 +09001777 nomca [IA-64] Disable machine check abort handling
1778
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001779 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001780
Andres Salomon83d73842007-10-12 23:04:06 +02001781 nomfgpt [X86-32] Disable Multi-Function General Purpose
1782 Timer usage (for AMD Geode machines).
1783
Jiri Kosina016ddd92010-01-18 17:05:40 +01001784 nopat [X86] Disable PAT (page attribute table extension of
1785 pagetables) support.
1786
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001787 norandmaps Don't use address space randomization. Equivalent to
1788 echo 0 > /proc/sys/kernel/randomize_va_space
1789
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001790 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001791
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001792 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001793 with UP alternatives
1794
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 noresidual [PPC] Don't use residual data on PReP machines.
1796
Randy Dunlapa9913042005-10-23 12:57:11 -07001797 noresume [SWSUSP] Disables resume and restores original swap
1798 space.
1799
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 no-scroll [VGA] Disables scrollback.
1801 This is required for the Braillex ib80-piezo Braille
1802 reader made by F.H. Papenmeier (Germany).
1803
1804 nosbagart [IA-64]
1805
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001806 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001807
Len Brown61ec7562007-08-16 03:34:22 -04001808 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1809 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810
Dave Jones97842212007-07-15 23:41:05 -07001811 nosoftlockup [KNL] Disable the soft-lockup detector.
1812
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001813 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001814 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001815
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 nosync [HW,M68K] Disables sync negotiation for all devices.
1817
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001818 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819
1820 nousb [USB] Disable the USB subsystem
1821
1822 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001823
Weidong Han2b2fd872009-04-17 16:42:12 +08001824 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1825
Fenghua Yua6c75b862008-03-14 13:57:08 -07001826 nptcg= [IA64] Override max number of concurrent global TLB
1827 purges which is reported from either PAL_VM_SUMMARY or
1828 SAL PALO.
1829
Yinghai Lu2b633e32010-02-10 01:20:37 -08001830 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1831 could support. nr_cpus=n : n >= 1 limits the kernel to
1832 supporting 'n' processors. Later in runtime you can not
1833 use hotplug cpu feature to put more cpu back to online.
1834 just like you compile the kernel NR_CPUS=n
1835
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001836 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1837
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001838 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1839 one of ['zone', 'node', 'default'] can be specified
1840 This can be set from sysctl after boot.
1841 See Documentation/sysctl/vm.txt for details.
1842
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001843 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1844 See Documentation/debugging-via-ohci1394.txt for more
1845 info.
1846
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001847 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1848 Rather than timing out after 20 ms if an EC
1849 command is not properly ACKed, override the length
1850 of the timeout. We have interrupts disabled while
1851 waiting for the ACK, so if this is set too high
1852 interrupts *may* be lost!
1853
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001854 omap_mux= [OMAP] Override bootloader pin multiplexing.
1855 Format: <mux_mode0.mode_name=value>...
1856 For example, to override I2C bus2:
1857 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1858
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 opl3= [HW,OSS]
1860 Format: <io>
1861
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 oprofile.timer= [HW]
1863 Use timer interrupt instead of performance counters
1864
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001865 oprofile.cpu_type= Force an oprofile cpu type
1866 This might be useful if you have an older oprofile
1867 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001868 Format: { arch_perfmon }
1869 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001870 perfmon on Intel CPUs instead of the
1871 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001872
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 osst= [HW,SCSI] SCSI Tape Driver
1874 Format: <buffer_size>,<write_threshold>
1875 See also Documentation/scsi/st.txt.
1876
1877 panic= [KNL] Kernel behaviour on panic
1878 Format: <timeout>
1879
1880 parkbd.port= [HW] Parallel port number the keyboard adapter is
1881 connected to, default is 0.
1882 Format: <parport#>
1883 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1884 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001885 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886
Randy Dunlapa9913042005-10-23 12:57:11 -07001887 parport= [HW,PPT] Specify parallel ports. 0 disables.
1888 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1889 Use 'auto' to force the driver to use any
1890 IRQ/DMA settings detected (the default is to
1891 ignore detected IRQ/DMA settings because of
1892 possible conflicts). You can specify the base
1893 address, IRQ, and DMA settings; IRQ and DMA
1894 should be numbers, or 'auto' (for using detected
1895 settings on that particular port), or 'nofifo'
1896 (to avoid using a FIFO even if it is detected).
1897 Parallel ports are assigned in the order they
1898 are specified on the command line, starting
1899 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900
Randy Dunlapa9913042005-10-23 12:57:11 -07001901 parport_init_mode= [HW,PPT]
1902 Configure VIA parallel port to operate in
1903 a specific mode. This is necessary on Pegasos
1904 computer where firmware has no options for setting
1905 up parallel port mode and sets it to spp.
1906 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 Format: [spp|ps2|epp|ecp|ecpepp]
1908
Randy Dunlapa9913042005-10-23 12:57:11 -07001909 pas2= [HW,OSS] Format:
1910 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1911
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 pas16= [HW,SCSI]
1913 See header of drivers/scsi/pas16.c.
1914
Andrew Mortondd287792006-03-23 03:00:57 -08001915 pause_on_oops=
1916 Halt all CPUs after the first oops has been printed for
1917 the specified number of seconds. This is to be used if
1918 your oopses keep scrolling off the screen.
1919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 pcbit= [HW,ISDN]
1921
1922 pcd. [PARIDE]
1923 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001924 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925
Randy Dunlapa9913042005-10-23 12:57:11 -07001926 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001927 earlydump [X86] dump PCI config space before the kernel
1928 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001929 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001930 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001931 the hardware directly. Use this if your machine
1932 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001933 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001934 hardware access methods are allowed. Use this
1935 if you experience crashes upon bootup and you
1936 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001937 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001938 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001939 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001940 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001941 noaer [PCIE] If the PCIEAER kernel config parameter is
1942 enabled, this kernel boot option can be used to
1943 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001944 nodomains [PCI] Disable support for multiple PCI
1945 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301946 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001947 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001948 check_enable_amd_mmconf [X86] check for and enable
1949 properly configured MMIO access to PCI
1950 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001951 nomsi [MSI] If the PCI_MSI kernel config parameter is
1952 enabled, this kernel boot option can be used to
1953 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001954 noioapicquirk [APIC] Disable all boot interrupt quirks.
1955 Safety option to keep boot IRQs enabled. This
1956 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001957 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1958 primary IO-APIC for bridges that cannot disable
1959 boot IRQs. This fixes a source of spurious IRQs
1960 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001961 noioapicreroute [APIC] Disable workaround that uses the
1962 boot IRQ equivalent of an IRQ that connects to
1963 a chipset where boot IRQs cannot be disabled.
1964 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001965 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001966 routing table. These calls are known to be buggy
1967 on several machines and they hang the machine
1968 when used, but on other computers it's the only
1969 way to get the interrupt routing table. Try
1970 this option if the kernel is unable to allocate
1971 IRQs or discover secondary PCI buses on your
1972 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001973 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001974 Use with caution as certain devices share
1975 address decoders between ROMs and other
1976 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001977 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001978 expansion ROMs that do not already have
1979 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001980 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001981 assigned automatically to PCI devices. You can
1982 make the kernel exclude IRQs of your ISA cards
1983 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001984 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001985 of the PIRQ table (normally generated
1986 by the BIOS) if it is outside the
1987 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001988 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001989 useful if the kernel is unable to find your
1990 secondary buses and you want to tell it
1991 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001992 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001993 numbers ourselves, overriding
1994 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001995 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001996 in the BIOS $PIR table. This is needed on
1997 some systems with broken BIOSes, notably
1998 some HP Pavilion N5400 and Omnibook XE3
1999 notebooks. This will have no effect if ACPI
2000 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002001 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002002 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002003 use_crs [X86] Use PCI host bridge window information
2004 from ACPI. On BIOSes from 2008 or later, this
2005 is enabled by default. If you need to use this,
2006 please report a bug.
2007 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2008 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002009 routeirq Do IRQ routing for all PCI devices.
2010 This is normally done in pci_enable_device(),
2011 so this option is a temporary workaround
2012 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002013 skip_isa_align [X86] do not align io start addr, so can
2014 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002015 firmware [ARM] Do not re-enumerate the bus but instead
2016 just use the configuration from the
2017 bootloader. This is currently used on
2018 IXP2000 systems where the bus has to be
2019 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002020 noearly [X86] Don't do any early type 1 scanning.
2021 This might help on some broken boards which
2022 machine check when some devices' config space
2023 is read. But various workarounds are disabled
2024 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002025 bfsort Sort PCI devices into breadth-first order.
2026 This sorting is done to get a device
2027 order compatible with older (<= 2.4) kernels.
2028 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002029 cbiosize=nn[KMG] The fixed amount of bus space which is
2030 reserved for the CardBus bridge's IO window.
2031 The default value is 256 bytes.
2032 cbmemsize=nn[KMG] The fixed amount of bus space which is
2033 reserved for the CardBus bridge's memory
2034 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002035 resource_alignment=
2036 Format:
2037 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2038 Specifies alignment and device to reassign
2039 aligned memory resources.
2040 If <order of align> is not specified,
2041 PAGE_SIZE is used as alignment.
2042 PCI-PCI bridge can be specified, if resource
2043 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002044 ecrc= Enable/disable PCIe ECRC (transaction layer
2045 end-to-end CRC checking).
2046 bios: Use BIOS/firmware settings. This is the
2047 the default.
2048 off: Turn ECRC off
2049 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002050
Chuck Ebberte5665a42008-09-24 20:40:34 -04002051 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2052 Management.
2053 off Disable ASPM.
2054 force Enable ASPM even on devices that claim not to support it.
2055 WARNING: Forcing ASPM on may cause system lockups.
2056
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002057 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockib27759f2010-06-18 17:04:22 +02002058 Format: {auto|force}[,nomsi]
2059 auto Use native PCIe PME signaling if the BIOS allows the
2060 kernel to control PCIe config registers of root ports.
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002061 force Use native PCIe PME signaling even if the BIOS refuses
2062 to allow the kernel to control the relevant PCIe config
2063 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002064 nomsi Do not use MSI for native PCIe PME signaling (this makes
2065 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002066
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 pcmv= [HW,PCMCIA] BadgePAD 4
2068
2069 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002070 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071
2072 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2073 boot time.
2074 Format: { 0 | 1 }
2075 See arch/parisc/kernel/pdc_chassis.c
2076
Tejun Heof58dc012009-08-14 15:00:50 +09002077 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002078 Currently supported values are "embed" and "page".
2079 Archs may support subset or none of the selections.
2080 See comments in mm/percpu.c for details on each
2081 allocator. This parameter is primarily for debugging
2082 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002083
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002085 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002086
2087 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002088 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089
2090 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002091 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092
2093 plip= [PPT,NET] Parallel port network link
2094 Format: { parport<nr> | timid | 0 }
2095 See also Documentation/parport.txt.
2096
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002097 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2098 Override pmtimer IOPort with a hex value.
2099 e.g. pmtmr=0x508
2100
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002101 pnp.debug [PNP]
2102 Enable PNP debug messages. This depends on the
2103 CONFIG_PNP_DEBUG_MESSAGES option.
2104
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105 pnpacpi= [ACPI]
2106 { off }
2107
2108 pnpbios= [ISAPNP]
2109 { on | off | curr | res | no-curr | no-res }
2110
2111 pnp_reserve_irq=
2112 [ISAPNP] Exclude IRQs for the autoconfiguration
2113
2114 pnp_reserve_dma=
2115 [ISAPNP] Exclude DMAs for the autoconfiguration
2116
2117 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002118 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119
2120 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002121 [ISAPNP] Exclude memory regions for the
2122 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123 Ranges are in pairs (memory base and size).
2124
Randy Dunlap4af94f32009-04-17 18:30:28 -07002125 ports= [IP_VS_FTP] IPVS ftp helper module
2126 Default is 21.
2127 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2128 may be specified.
2129 Format: <port>,<port>....
2130
Ingo Molnar45807a12007-07-15 23:40:10 -07002131 print-fatal-signals=
2132 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002133
2134 If enabled, warn about various signal handling
2135 related application anomalies: too many signals,
2136 too many POSIX.1 timers, fatal signals causing a
2137 coredump - etc.
2138
2139 If you hit the warning due to signal overflow,
2140 you might want to try "ulimit -i unlimited".
2141
Ingo Molnar45807a12007-07-15 23:40:10 -07002142 default: off.
2143
Randy Dunlape84845c2007-07-15 23:40:25 -07002144 printk.time= Show timing data prefixed to each printk message line
2145 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2146
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002147 processor.max_cstate= [HW,ACPI]
2148 Limit processor to maximum C-state
2149 max_cstate=9 overrides any DMI blacklist limit.
2150
2151 processor.nocst [HW,ACPI]
2152 Ignore the _CST method to determine C-states,
2153 instead using the legacy FADT method
2154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002156 Format: [schedule,]<number>
2157 Param: "schedule" - profile schedule points.
2158 Param: <number> - step/bucket size as a power of 2 for
2159 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002160 Param: "sleep" - profile D-state sleeping (millisecs).
2161 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002162 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2165 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002166 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167
Randy Dunlapa9913042005-10-23 12:57:11 -07002168 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2169 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2171 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002172 psmouse.resetafter= [HW,MOUSE]
2173 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 (0 = never).
2175 psmouse.resolution=
2176 [HW,MOUSE] Set desired mouse resolution, in dpi.
2177 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002178 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 0 = disabled, 1 = enabled (default).
2180
2181 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002182 Format:
2183 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184
2185 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002186 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187
Kay Sieversdc8c8582007-08-15 12:25:38 +02002188 pty.legacy_count=
2189 [KNL] Number of legacy pty's. Overwrites compiled-in
2190 default number.
2191
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002192 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002193
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194 r128= [HW,DRM]
2195
2196 raid= [HW,RAID]
2197 See Documentation/md.txt.
2198
Randy Dunlapa9913042005-10-23 12:57:11 -07002199 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002200 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002201
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002203 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002205 rcupdate.blimit= [KNL,BOOT]
2206 Set maximum number of finished RCU callbacks to process
2207 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002208
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002209 rcupdate.qhimark= [KNL,BOOT]
2210 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002211 RCU callbacks over which batch limiting is disabled.
2212
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002213 rcupdate.qlowmark= [KNL,BOOT]
2214 Set threshold of queued RCU callbacks below which
2215 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002216
Olof Johanssonffdfc402005-09-06 15:17:19 -07002217 rdinit= [KNL]
2218 Format: <full_path>
2219 Run specified binary instead of /init from the ramdisk,
2220 used for early userspace startup. See initrd.
2221
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002222 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002224 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002225
Paul Jackson46b6d942008-07-04 10:00:09 -07002226 relax_domain_level=
2227 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002228 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002229
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2231
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002232 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002233 Format: nn[KMG]
2234 Reserves a hole at the top of the kernel virtual
2235 address space.
2236
Vivek Goyal7e962872006-09-27 01:50:44 -07002237 reset_devices [KNL] Force drivers to reset the underlying device
2238 during initialization.
2239
Randy Dunlapa9913042005-10-23 12:57:11 -07002240 resume= [SWSUSP]
2241 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002242
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002243 resume_offset= [SWSUSP]
2244 Specify the offset from the beginning of the partition
2245 given by "resume=" at which the swap header is located,
2246 in <PAGE_SIZE> units (needed only for swap files).
2247 See Documentation/power/swsusp-and-swap-files.txt
2248
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002249 retain_initrd [RAM] Keep initrd memory after extraction
2250
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251 rhash_entries= [KNL,NET]
2252 Set number of hash buckets for route cache
2253
2254 riscom8= [HW,SERIAL]
2255 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2256
2257 ro [KNL] Mount root device read-only on boot
2258
2259 root= [KNL] Root filesystem
2260
2261 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2262 mount the root filesystem
2263
2264 rootflags= [KNL] Set root filesystem mount option string
2265
2266 rootfstype= [KNL] Set root filesystem type
2267
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002268 rootwait [KNL] Wait (indefinitely) for root device to show up.
2269 Useful for devices that are detected asynchronously
2270 (e.g. USB and MMC devices).
2271
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 rw [KNL] Mount root device read-write on boot
2273
2274 S [KNL] Run init in single mode
2275
2276 sa1100ir [NET]
2277 See drivers/net/irda/sa1100_ir.c.
2278
Linus Torvalds1da177e2005-04-16 15:20:36 -07002279 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002280
Mike Travisf6630112009-11-17 18:22:15 -06002281 sched_debug [KNL] Enables verbose scheduler debug messages.
2282
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283 scsi_debug_*= [SCSI]
2284 See drivers/scsi/scsi_debug.c.
2285
2286 scsi_default_dev_flags=
2287 [SCSI] SCSI default device flags
2288 Format: <integer>
2289
2290 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2291 Format: <vendor>:<model>:<flags>
2292 (flags are integer value)
2293
Randy Dunlap6af66322007-11-14 16:52:25 -08002294 scsi_logging_level= [SCSI] a bit mask of logging levels
2295 See drivers/scsi/scsi_logging.h for bits. Also
2296 settable via sysctl at dev.scsi.logging_level
2297 (/proc/sys/dev/scsi/logging_level).
2298 There is also a nice 'scsi_logging_level' script in the
2299 S390-tools package, available for download at
2300 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002302 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2303 discovered. async scans them in kernel threads,
2304 allowing boot to proceed. none ignores them, expecting
2305 user space to do the scan.
2306
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002307 security= [SECURITY] Choose a security module to enable at boot.
2308 If this boot parameter is not specified, only the first
2309 security module asking for security registration will be
2310 loaded. An invalid security module name will be treated
2311 as if no module has been chosen.
2312
2313 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002314 Format: { "0" | "1" }
2315 See security/selinux/Kconfig help text.
2316 0 -- disable.
2317 1 -- enable.
2318 Default value is set via kernel config option.
2319 If enabled at boot time, /selinux/disable can be used
2320 later to disable prior to initial policy load.
2321
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002322 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324 shapers= [NET]
2325 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002326
Yinghai Lub05f78f2008-08-22 01:32:50 -07002327 show_msr= [x86] show boot-time MSR settings
2328 Format: { <integer> }
2329 Show boot-time (BIOS-initialized) MSR settings.
2330 The parameter means the number of CPUs to show,
2331 for example 1 means boot CPU only.
2332
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 sim710= [SCSI,HW]
2334 See header of drivers/scsi/sim710.c.
2335
2336 simeth= [IA-64]
2337 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002338
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339 slram= [HW,MTD]
2340
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002341 slub_debug[=options[,slabs]] [MM, SLUB]
2342 Enabling slub_debug allows one to determine the
2343 culprit if slab objects become corrupted. Enabling
2344 slub_debug can create guard zones around objects and
2345 may poison objects when not in use. Also tracks the
2346 last alloc / free. For more information see
2347 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002348
2349 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002350 Determines the maximum allowed order for slabs.
2351 A high setting may cause OOMs due to memory
2352 fragmentation. For more information see
2353 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002354
2355 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002356 The minimum number of objects per slab. SLUB will
2357 increase the slab order up to slub_max_order to
2358 generate a sufficiently large slab able to contain
2359 the number of objects indicated. The higher the number
2360 of objects the smaller the overhead of tracking slabs
2361 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002362 For more information see Documentation/vm/slub.txt.
2363
2364 slub_min_order= [MM, SLUB]
2365 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002366 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002367 For more information see Documentation/vm/slub.txt.
2368
2369 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002370 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002371 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002372 allocs to different slabs. Debug options disable
2373 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002374 For more information see Documentation/vm/slub.txt.
2375
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 smart2= [HW]
2377 Format: <io1>[,<io2>[,...,<io8>]]
2378
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002379 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002380 attempt to substitute SMP alternatives once at boot.
2381
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002382 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2383 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2384 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2385 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2386 smsc-ircc2.ircc_irq= [HW] IRQ line
2387 smsc-ircc2.ircc_dma= [HW] DMA channel
2388 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2389 0: Toshiba Satellite 1800 (GP data pin select)
2390 1: Fast pin select (default)
2391 2: ATC IRMode
2392
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393 snd-ad1816a= [HW,ALSA]
2394
2395 snd-ad1848= [HW,ALSA]
2396
2397 snd-ali5451= [HW,ALSA]
2398
2399 snd-als100= [HW,ALSA]
2400
2401 snd-als4000= [HW,ALSA]
2402
2403 snd-azt2320= [HW,ALSA]
2404
2405 snd-cmi8330= [HW,ALSA]
2406
2407 snd-cmipci= [HW,ALSA]
2408
2409 snd-cs4231= [HW,ALSA]
2410
2411 snd-cs4232= [HW,ALSA]
2412
2413 snd-cs4236= [HW,ALSA]
2414
2415 snd-cs4281= [HW,ALSA]
2416
2417 snd-cs46xx= [HW,ALSA]
2418
2419 snd-dt019x= [HW,ALSA]
2420
2421 snd-dummy= [HW,ALSA]
2422
2423 snd-emu10k1= [HW,ALSA]
2424
2425 snd-ens1370= [HW,ALSA]
2426
2427 snd-ens1371= [HW,ALSA]
2428
2429 snd-es968= [HW,ALSA]
2430
2431 snd-es1688= [HW,ALSA]
2432
2433 snd-es18xx= [HW,ALSA]
2434
2435 snd-es1938= [HW,ALSA]
2436
2437 snd-es1968= [HW,ALSA]
2438
2439 snd-fm801= [HW,ALSA]
2440
2441 snd-gusclassic= [HW,ALSA]
2442
2443 snd-gusextreme= [HW,ALSA]
2444
2445 snd-gusmax= [HW,ALSA]
2446
2447 snd-hdsp= [HW,ALSA]
2448
2449 snd-ice1712= [HW,ALSA]
2450
2451 snd-intel8x0= [HW,ALSA]
2452
2453 snd-interwave= [HW,ALSA]
2454
2455 snd-interwave-stb=
2456 [HW,ALSA]
2457
2458 snd-korg1212= [HW,ALSA]
2459
2460 snd-maestro3= [HW,ALSA]
2461
2462 snd-mpu401= [HW,ALSA]
2463
2464 snd-mtpav= [HW,ALSA]
2465
2466 snd-nm256= [HW,ALSA]
2467
2468 snd-opl3sa2= [HW,ALSA]
2469
2470 snd-opti92x-ad1848=
2471 [HW,ALSA]
2472
2473 snd-opti92x-cs4231=
2474 [HW,ALSA]
2475
2476 snd-opti93x= [HW,ALSA]
2477
2478 snd-pmac= [HW,ALSA]
2479
2480 snd-rme32= [HW,ALSA]
2481
2482 snd-rme96= [HW,ALSA]
2483
2484 snd-rme9652= [HW,ALSA]
2485
2486 snd-sb8= [HW,ALSA]
2487
2488 snd-sb16= [HW,ALSA]
2489
2490 snd-sbawe= [HW,ALSA]
2491
2492 snd-serial= [HW,ALSA]
2493
2494 snd-sgalaxy= [HW,ALSA]
2495
2496 snd-sonicvibes= [HW,ALSA]
2497
2498 snd-sun-amd7930=
2499 [HW,ALSA]
2500
2501 snd-sun-cs4231= [HW,ALSA]
2502
2503 snd-trident= [HW,ALSA]
2504
2505 snd-usb-audio= [HW,ALSA,USB]
2506
2507 snd-via82xx= [HW,ALSA]
2508
2509 snd-virmidi= [HW,ALSA]
2510
2511 snd-wavefront= [HW,ALSA]
2512
2513 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002514
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002515 softlockup_panic=
2516 [KNL] Should the soft-lockup detector generate panics.
2517
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2519 See Documentation/sonypi.txt
2520
2521 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002522 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523
2524 spia_io_base= [HW,MTD]
2525 spia_fio_base=
2526 spia_pedr=
2527 spia_peddr=
2528
2529 sscape= [HW,OSS]
2530 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002531
Linus Torvalds1da177e2005-04-16 15:20:36 -07002532 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2533 See Documentation/scsi/st.txt.
2534
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002535 stacktrace [FTRACE]
2536 Enabled the stack tracer on boot up.
2537
Linus Torvalds1da177e2005-04-16 15:20:36 -07002538 sti= [PARISC,HW]
2539 Format: <num>
2540 Set the STI (builtin display/keyboard on the HP-PARISC
2541 machines) console (graphic card) which should be used
2542 as the initial boot-console.
2543 See also comment in drivers/video/console/sticore.c.
2544
2545 sti_font= [HW]
2546 See comment in drivers/video/console/sticore.c.
2547
2548 stifb= [HW]
2549 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2550
Trond Myklebustcbf11072009-08-09 15:06:19 -04002551 sunrpc.min_resvport=
2552 sunrpc.max_resvport=
2553 [NFS,SUNRPC]
2554 SunRPC servers often require that client requests
2555 originate from a privileged port (i.e. a port in the
2556 range 0 < portnr < 1024).
2557 An administrator who wishes to reserve some of these
2558 ports for other uses may adjust the range that the
2559 kernel's sunrpc client considers to be privileged
2560 using these two parameters to set the minimum and
2561 maximum port values.
2562
Greg Banks42a7fc42007-03-06 01:42:23 -08002563 sunrpc.pool_mode=
2564 [NFS]
2565 Control how the NFS server code allocates CPUs to
2566 service thread pools. Depending on how many NICs
2567 you have and where their interrupts are bound, this
2568 option will affect which CPUs will do NFS serving.
2569 Note: this parameter cannot be changed while the
2570 NFS server is running.
2571
2572 auto the server chooses an appropriate mode
2573 automatically using heuristics
2574 global a single global pool contains all CPUs
2575 percpu one pool for each CPU
2576 pernode one pool for each NUMA node (equivalent
2577 to global on non-NUMA machines)
2578
Trond Myklebustcbf11072009-08-09 15:06:19 -04002579 sunrpc.tcp_slot_table_entries=
2580 sunrpc.udp_slot_table_entries=
2581 [NFS,SUNRPC]
2582 Sets the upper limit on the number of simultaneous
2583 RPC calls that can be sent from the client to a
2584 server. Increasing these values may allow you to
2585 improve throughput, but will also increase the
2586 amount of memory reserved for use by the client.
2587
Linus Torvalds1da177e2005-04-16 15:20:36 -07002588 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002589
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590 switches= [HW,M68k]
2591
2592 sym53c416= [HW,SCSI]
2593 See header of drivers/scsi/sym53c416.c.
2594
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002595 sysrq_always_enabled
2596 [KNL]
2597 Ignore sysrq setting - this boot parameter will
2598 neutralize any effect of /proc/sys/kernel/sysrq.
2599 Useful for debugging.
2600
Linus Torvalds1da177e2005-04-16 15:20:36 -07002601 t128= [HW,SCSI]
2602 See header of drivers/scsi/t128.c.
2603
2604 tdfx= [HW,DRM]
2605
David Brownell77437fd2008-07-23 21:28:33 -07002606 test_suspend= [SUSPEND]
2607 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2608 standby suspend) as the system sleep state to briefly
2609 enter during system startup. The system is woken from
2610 this state using a wakeup-capable RTC alarm.
2611
Linus Torvalds1da177e2005-04-16 15:20:36 -07002612 thash_entries= [KNL,NET]
2613 Set number of hash buckets for TCP connection
2614
Len Brownf8707ec2007-08-12 00:12:54 -04002615 thermal.act= [HW,ACPI]
2616 -1: disable all active trip points in all thermal zones
2617 <degrees C>: override all lowest active trip points
2618
Len Brownc52a7412007-08-14 15:49:32 -04002619 thermal.crt= [HW,ACPI]
2620 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002621 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002622
Len Brownf5487142007-08-12 00:12:44 -04002623 thermal.nocrt= [HW,ACPI]
2624 Set to disable actions on ACPI thermal zone
2625 critical and hot trip points.
2626
Len Brown72b33ef2007-08-12 00:12:17 -04002627 thermal.off= [HW,ACPI]
2628 1: disable ACPI thermal control
2629
Len Browna70cdc52007-08-12 00:12:35 -04002630 thermal.psv= [HW,ACPI]
2631 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002632 <degrees C>: override all passive trip points to this
2633 value
Len Browna70cdc52007-08-12 00:12:35 -04002634
Len Brown730ff342007-08-12 00:12:26 -04002635 thermal.tzp= [HW,ACPI]
2636 Specify global default ACPI thermal zone polling rate
2637 <deci-seconds>: poll all this frequency
2638 0: no polling (default)
2639
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640 tmscsim= [HW,SCSI]
2641 See comment before function dc390_setup() in
2642 drivers/scsi/tmscsim.c.
2643
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002644 topology= [S390]
2645 Format: {off | on}
2646 Specify if the kernel should make use of the cpu
2647 topology informations if the hardware supports these.
2648 The scheduler will make use of these informations and
2649 e.g. base its process migration decisions on it.
2650 Default is off.
2651
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652 tp720= [HW,PS2]
2653
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002654 tpm_suspend_pcr=[HW,TPM]
2655 Format: integer pcr id
2656 Specify that at suspend time, the tpm driver
2657 should extend the specified pcr with zeros,
2658 as a workaround for some chips which fail to
2659 flush the last written pcr on TPM_SaveState.
2660 This will guarantee that all the other pcrs
2661 are saved.
2662
Li Zefan9d612be2009-06-24 17:33:15 +08002663 trace_buf_size=nn[KMG]
2664 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002665
Li Zefan020e5f82009-07-01 10:47:05 +08002666 trace_event=[event-list]
2667 [FTRACE] Set and start specified trace events in order
2668 to facilitate early boot debugging.
2669 See also Documentation/trace/events.txt
2670
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002672 Format:
2673 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2674
Alok Kataria395628e2008-10-24 17:22:01 -07002675 tsc= Disable clocksource-must-verify flag for TSC.
2676 Format: <string>
2677 [x86] reliable: mark tsc clocksource as reliable, this
2678 disables clocksource verification at runtime.
2679 Used to enable high-resolution timer mode on older
2680 hardware, and in virtualized environment.
2681
Randy Dunlapa9913042005-10-23 12:57:11 -07002682 turbografx.map[2|3]= [HW,JOY]
2683 TurboGraFX parallel port interface
2684 Format:
2685 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 See also Documentation/input/joystick-parport.txt
2687
2688 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2689 See header of drivers/scsi/u14-34f.c.
2690
2691 uart401= [HW,OSS]
2692 Format: <io>,<irq>
2693
2694 uart6850= [HW,OSS]
2695 Format: <io>,<irq>
2696
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002697 uhash_entries= [KNL,NET]
2698 Set number of hash buckets for UDP/UDP-Lite connections
2699
Alan Stern5f8364b2006-12-05 16:29:55 -05002700 uhci-hcd.ignore_oc=
2701 [USB] Ignore overcurrent events (default N).
2702 Some badly-designed motherboards generate lots of
2703 bogus events, for ports that aren't wired to
2704 anything. Set this parameter to avoid log spamming.
2705 Note that genuine overcurrent events won't be
2706 reported either.
2707
Simon Arlotte3a61b02008-07-19 23:32:54 +01002708 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302709 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002710 Set unknown_nmi_panic=1 early on boot.
2711
Alan Sternb5e795f2007-02-20 15:00:53 -05002712 usbcore.autosuspend=
2713 [USB] The autosuspend time delay (in seconds) used
2714 for newly-detected USB devices (default 2). This
2715 is the time required before an idle device will be
2716 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002717 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002718
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002719 usbcore.usbfs_snoop=
2720 [USB] Set to log all usbfs traffic (default 0 = off).
2721
2722 usbcore.blinkenlights=
2723 [USB] Set to cycle leds on hubs (default 0 = off).
2724
2725 usbcore.old_scheme_first=
2726 [USB] Start with the old device initialization
2727 scheme (default 0 = off).
2728
2729 usbcore.use_both_schemes=
2730 [USB] Try the other device initialization scheme
2731 if the first one fails (default 1 = enabled).
2732
2733 usbcore.initial_descriptor_timeout=
2734 [USB] Specifies timeout for the initial 64-byte
2735 USB_REQ_GET_DESCRIPTOR request in milliseconds
2736 (default 5000 = 5.0 seconds).
2737
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738 usbhid.mousepoll=
2739 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002740
Alan Sternd4f373e2008-11-10 14:07:45 -05002741 usb-storage.delay_use=
2742 [UMS] The delay in seconds before a new device is
2743 scanned for Logical Units (default 5).
2744
2745 usb-storage.quirks=
2746 [UMS] A list of quirks entries to supplement or
2747 override the built-in unusual_devs list. List
2748 entries are separated by commas. Each entry has
2749 the form VID:PID:Flags where VID and PID are Vendor
2750 and Product ID values (4-digit hex numbers) and
2751 Flags is a set of characters, each corresponding
2752 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002753 a = SANE_SENSE (collect more than 18 bytes
2754 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002755 b = BAD_SENSE (don't collect more than 18
2756 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002757 c = FIX_CAPACITY (decrease the reported
2758 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002759 h = CAPACITY_HEURISTICS (decrease the
2760 reported device capacity by one
2761 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002762 i = IGNORE_DEVICE (don't bind to this
2763 device);
2764 l = NOT_LOCKABLE (don't try to lock and
2765 unlock ejectable media);
2766 m = MAX_SECTORS_64 (don't transfer more
2767 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002768 o = CAPACITY_OK (accept the capacity
2769 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002770 r = IGNORE_RESIDUE (the device reports
2771 bogus residue values);
2772 s = SINGLE_LUN (the device has only one
2773 Logical Unit);
2774 w = NO_WP_DETECT (don't test whether the
2775 medium is write-protected).
2776 Example: quirks=0419:aaf5:rl,0421:0433:rc
2777
Ian Campbell14315592010-02-17 10:38:10 +00002778 userpte=
2779 [X86] Flags controlling user PTE allocations.
2780
2781 nohigh = do not allocate PTE pages in
2782 HIGHMEM regardless of setting
2783 of CONFIG_HIGHPTE.
2784
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302785 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002786 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002787 vdso=1: enable VDSO (default)
2788 vdso=0: disable VDSO mapping
2789
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302790 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002791 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2792 vdso32=1: enable 32-bit VDSO (default)
2793 vdso32=0: disable 32-bit VDSO mapping
2794
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002795 vector= [IA-64,SMP]
2796 vector=percpu: enable percpu vector domain
2797
Linus Torvalds1da177e2005-04-16 15:20:36 -07002798 video= [FB] Frame buffer configuration
2799 See Documentation/fb/modedb.txt.
2800
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002801 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002802 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002803 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804 Use vga=ask for menu.
2805 This is actually a boot loader parameter; the value is
2806 passed to the kernel using a special protocol.
2807
Randy Dunlapa9913042005-10-23 12:57:11 -07002808 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809 size of <nn>. This can be used to increase the
2810 minimum size (128MB on x86). It can also be used to
2811 decrease the size and leave more room for directly
2812 mapped kernel RAM.
2813
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002814 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2815 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002816
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002817 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2818 Format: <command>
2819
2820 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2821 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002822
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002823 vt.cur_default= [VT] Default cursor shape.
2824 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2825 the parameters of the <Esc>[?A;B;Cc escape sequence;
2826 see VGA-softcursor.txt. Default: 2 = underline.
2827
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002828 vt.default_blu= [VT]
2829 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2830 Change the default blue palette of the console.
2831 This is a 16-member array composed of values
2832 ranging from 0-255.
2833
2834 vt.default_grn= [VT]
2835 Format: <green0>,<green1>,<green2>,...,<green15>
2836 Change the default green palette of the console.
2837 This is a 16-member array composed of values
2838 ranging from 0-255.
2839
2840 vt.default_red= [VT]
2841 Format: <red0>,<red1>,<red2>,...,<red15>
2842 Change the default red palette of the console.
2843 This is a 16-member array composed of values
2844 ranging from 0-255.
2845
2846 vt.default_utf8=
2847 [VT]
2848 Format=<0|1>
2849 Set system-wide default UTF-8 mode for all tty's.
2850 Default is 1, i.e. UTF-8 mode is enabled for all
2851 newly opened terminals.
2852
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002853 vt.global_cursor_default=
2854 [VT]
2855 Format=<-1|0|1>
2856 Set system-wide default for whether a cursor
2857 is shown on new VTs. Default is -1,
2858 i.e. cursors will be created by default unless
2859 overridden by individual drivers. 0 will hide
2860 cursors, 1 will display them.
2861
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862 waveartist= [HW,OSS]
2863 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002864
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865 wd33c93= [HW,SCSI]
2866 See header of drivers/scsi/wd33c93.c.
2867
2868 wd7000= [HW,SCSI]
2869 See header of drivers/scsi/wd7000.c.
2870
Randy Dunlap4724ba572010-05-03 11:42:52 -07002871 watchdog timers [HW,WDT] For information on watchdog timers,
2872 see Documentation/watchdog/watchdog-parameters.txt
2873 or other driver-specific files in the
2874 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002876 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2877 default x2apic cluster mode on platforms
2878 supporting x2apic.
2879
Jacob Panbb24c472009-09-02 07:37:17 -07002880 x86_mrst_timer= [X86-32,APBT]
2881 Choose timer option for x86 Moorestown MID platform.
2882 Two valid options are apbt timer only and lapic timer
2883 plus one apbt timer for broadcast timer.
2884 x86_mrst_timer=apbt_only | lapic_and_apbt
2885
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2887 xd_geo= See header of drivers/block/xd.c.
2888
2889 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002890 Format:
2891 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892
Randy Dunlapa9913042005-10-23 12:57:11 -07002893______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002894
2895TODO:
2896
2897 Add documentation for ALSA options.
2898 Add more DRM drivers.