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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050061 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020062 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070063 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070072 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070073 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070076 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070079 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070083 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
93 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070094 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 SELINUX SELinux support is enabled.
96 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090097 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500102 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300103 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500105 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700113 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700116 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119In addition, the following text indicates that the option:
120
121 BUGS= Relates to possible processor bugs on the said processor.
122 KNL Is a kernel start-up parameter.
123 BOOT Is a boot loader parameter.
124
125Parameters denoted with BOOT are actually interpreted by the boot
126loader, and have no meaning to the kernel directly.
127Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500128need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Karsten Weiss55588702007-02-13 13:26:21 +0100130There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700131See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
134a trailing = on the name of any parameter states that that parameter will
135be entered as an environment variable, whereas its absence indicates that
136it will appear as a kernel argument readable via /proc/cmdline by programs
137running once the system is up.
138
jens m. noedler9c4751f2006-09-29 02:00:27 -0700139The number of kernel parameters is not limited, but the length of the
140complete command line (parameters including spaces etc.) is limited to
141a fixed number of characters. This limit depends on the architecture
142and is between 256 and 4096 characters. It is defined in the file
143./include/asm/setup.h as COMMAND_LINE_SIZE.
144
145
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530146 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800147 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500148 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 force -- enable ACPI if default was off
150 off -- disable ACPI if default was on
151 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700152 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800154 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800155 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Randy Dunlap53471122008-03-12 18:10:51 -0400157 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
Len Browna1fdcc02007-03-11 03:26:14 -0400159 acpi_apic_instance= [ACPI, IOAPIC]
160 Format: <int>
161 2: use 2nd APIC table, if available
162 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400163 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400164
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200165 acpi_backlight= [HW,ACPI]
166 acpi_backlight=vendor
167 acpi_backlight=video
168 If set to vendor, prefer vendor specific driver
169 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
170 of the ACPI video.ko driver.
171
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700172 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
173 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700175 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
176 debug output. Bits in debug_layer correspond to a
177 _COMPONENT in an ACPI source file, e.g.,
178 #define _COMPONENT ACPI_PCI_COMPONENT
179 Bits in debug_level correspond to a level in
180 ACPI_DEBUG_PRINT statements, e.g.,
181 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600182 The debug_level mask defaults to "info". See
183 Documentation/acpi/debug.txt for more information about
184 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600186 Enable processor driver info messages:
187 acpi.debug_layer=0x20000000
188 Enable PCI/PCI interrupt routing info messages:
189 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700190 Enable AML "Debug" output, i.e., stores to the Debug
191 object while interpreting AML:
192 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700193 Enable all messages related to ACPI hardware:
194 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200195
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700196 Some values produce so much output that the system is
197 unusable. The "log_buf_len" parameter may be useful
198 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800199
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700200 acpi_display_output= [HW,ACPI]
201 acpi_display_output=vendor
202 acpi_display_output=video
203 See above.
204
205 acpi_irq_balance [HW,ACPI]
206 ACPI will balance active IRQs
207 default in APIC mode
208
209 acpi_irq_nobalance [HW,ACPI]
210 ACPI will not move active IRQs (default)
211 default in PIC mode
212
213 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
214 Format: <irq>,<irq>...
215
216 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
217 use by PCI
218 Format: <irq>,<irq>...
219
220 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
221
222 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
223 Format: To spoof as Windows 98: ="Microsoft Windows"
224
225 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
226 acpi_osi="string1" # add string1 -- only one string
227 acpi_osi="!string2" # remove built-in string2
228 acpi_osi= # disable all strings
229
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530230 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700231 Override the pmtimer bug detection: force the kernel
232 to assume that this machine's pmtimer latches its value
233 and always returns good values.
234
Randy Dunlap4af94f32009-04-17 18:30:28 -0700235 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
236 Format: { level | edge | high | low }
237
238 acpi_serialize [HW,ACPI] force serialization of AML methods
239
240 acpi_skip_timer_override [HW,ACPI]
241 Recognize and ignore IRQ0/pin2 Interrupt Override.
242 For broken nForce2 BIOS resulting in XT-PIC timer.
243
244 acpi_sleep= [HW,ACPI] Sleep options
245 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800246 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700247 See Documentation/power/video.txt for information on
248 s3_bios and s3_mode.
249 s3_beep is for debugging; it makes the PC's speaker beep
250 as soon as the kernel's real-mode entry point is called.
251 s4_nohwsig prevents ACPI hardware signature from being
252 used during resume from hibernation.
253 old_ordering causes the ACPI 1.0 ordering of the _PTS
254 control method, with respect to putting devices into
255 low power states, to be enforced (the ACPI 2.0 ordering
256 of _PTS is used by default).
257 s4_nonvs prevents the kernel from saving/restoring the
258 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800259 sci_force_enable causes the kernel to set SCI_EN directly
260 on resume from S1/S3 (which is against the ACPI spec,
261 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700262
263 acpi_use_timer_override [HW,ACPI]
264 Use timer override. For some broken Nvidia NF5 boards
265 that require a timer override, but don't have HPET
266
Luca Tettamanti7e905602009-03-30 00:01:27 +0200267 acpi_enforce_resources= [ACPI]
268 { strict | lax | no }
269 Check for resource conflicts between native drivers
270 and ACPI OperationRegions (SystemIO and SystemMemory
271 only). IO ports and memory declared in ACPI might be
272 used by the ACPI subsystem in arbitrary AML code and
273 can interfere with legacy drivers.
274 strict (default): access to resources claimed by ACPI
275 is denied; legacy drivers trying to access reserved
276 resources will fail to bind to device using them.
277 lax: access to resources claimed by ACPI is allowed;
278 legacy drivers trying to access reserved resources
279 will bind successfully but a warning message is logged.
280 no: ACPI OperationRegions are not marked as reserved,
281 no further checks are performed.
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 ad1848= [HW,OSS]
284 Format: <io>,<irq>,<dma>,<dma2>,<type>
285
Randy Dunlap4af94f32009-04-17 18:30:28 -0700286 add_efi_memmap [EFI; X86] Include EFI memory map in
287 kernel's map of available physical RAM.
288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 advansys= [HW,SCSI]
290 See header of drivers/scsi/advansys.c.
291
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 aedsp16= [HW,OSS] Audio Excel DSP 16
293 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
294 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700295
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 aha152x= [HW,SCSI]
303 See Documentation/scsi/aha152x.txt.
304
305 aha1542= [HW,SCSI]
306 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
307
308 aic7xxx= [HW,SCSI]
309 See Documentation/scsi/aic7xxx.txt.
310
311 aic79xx= [HW,SCSI]
312 See Documentation/scsi/aic79xx.txt.
313
Russell Kingd944d542010-02-20 16:13:29 +0000314 alignment= [KNL,ARM]
315 Allow the default userspace alignment fault handler
316 behaviour to be specified. Bit 0 enables warnings,
317 bit 1 enables fixups, and bit 2 sends a segfault.
318
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
321 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900322 fullflush - enable flushing of IO/TLB entries when
323 they are unmapped. Otherwise they are
324 flushed before they will be reused, which
325 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200326 off - do not initialize any AMD IOMMU found in
327 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900328
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 amijoy.map= [HW,JOY] Amiga joystick support
330 Map of devices attached to JOY0DAT and JOY1DAT
331 Format: <a>,<b>
332 See also Documentation/kernel/input/joystick.txt
333
334 analog.map= [HW,JOY] Analog joystick and gamepad support
335 Specifies type or capabilities of an analog joystick
336 connected to one of 16 gameports
337 Format: <type1>,<type2>,..<type16>
338
Randy Dunlapa9913042005-10-23 12:57:11 -0700339 apc= [HW,SPARC]
340 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 Format: noidle
342 Disable APC CPU standby support. SPARCstation-Fox does
343 not play well with APC CPU idle - disable it if you have
344 APC and your system crashes randomly.
345
Randy Dunlapca1eda22009-05-06 16:02:58 -0700346 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700347 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 Format: { quiet (default) | verbose | debug }
349 Change the amount of debugging information output
350 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700351
Brian Haleyb0f83b22010-02-04 13:36:50 -0800352 autoconf= [IPV6]
353 See Documentation/networking/ipv6.txt.
354
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400355 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
356 Limit apic dumping. The parameter defines the maximal
357 number of local apics being dumped. Also it is possible
358 to set it to "all" by meaning -- no limit here.
359 Format: { 1 (default) | 2 | ... | all }.
360 The parameter valid if only apic=debug or
361 apic=verbose is specified.
362 Example: apic=debug show_lapic=all
363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700365 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
368 Format: <io>,<irq>,<nodeID>
369
370 ataflop= [HW,M68k]
371
372 atarimouse= [HW,MOUSE] Atari Mouse
373
374 atascsi= [HW,SCSI] Atari SCSI
375
376 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
377 EzKey and similar keyboards
378
379 atkbd.reset= [HW] Reset keyboard during initialization
380
Randy Dunlapa9913042005-10-23 12:57:11 -0700381 atkbd.set= [HW] Select keyboard code set
382 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
384 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
385 keyboards
386
387 atkbd.softraw= [HW] Choose between synthetic and real raw mode
388 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700389
390 atkbd.softrepeat= [HW]
391 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
393 autotest [IA64]
394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 baycom_epp= [HW,AX25]
396 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700397
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
399 Format: <io>,<mode>
400 See header of drivers/net/hamradio/baycom_par.c.
401
Randy Dunlapa9913042005-10-23 12:57:11 -0700402 baycom_ser_fdx= [HW,AX25]
403 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 Format: <io>,<irq>,<mode>[,<baud>]
405 See header of drivers/net/hamradio/baycom_ser_fdx.c.
406
Randy Dunlapa9913042005-10-23 12:57:11 -0700407 baycom_ser_hdx= [HW,AX25]
408 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 Format: <io>,<irq>,<mode>
410 See header of drivers/net/hamradio/baycom_ser_hdx.c.
411
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700412 boot_delay= Milliseconds to delay each printk during boot.
413 Values larger than 10 seconds (10000) are changed to
414 no delay (0).
415 Format: integer
416
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700417 bootmem_debug [KNL] Enable bootmem allocator debug messages.
418
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700420 bttv.radio= Most important insmod options are available as
421 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
423 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
424
425 BusLogic= [HW,SCSI]
426 See drivers/scsi/BusLogic.c, comment before function
427 BusLogic_ParseDriverOptions().
428
429 c101= [NET] Moxa C101 synchronous serial card
430
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700431 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 Sometimes CPU hardware bugs make them report the cache
433 size incorrectly. The kernel will attempt work arounds
434 to fix known problems, but for some CPUs it is not
435 possible to determine what the correct size should be.
436 This option provides an override for these situations.
437
James Morris20510f22007-10-16 23:31:32 -0700438 capability.disable=
439 [SECURITY] Disable capabilities. This would normally
440 be used only if an alternative security model is to be
441 configured. Potentially dangerous and should only be
442 used if you are entirely sure of the consequences.
443
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100444 ccw_timeout_log [S390]
445 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446
Paul Menage8bab8dd2008-04-04 14:29:57 -0700447 cgroup_disable= [KNL] Disable a particular controller
448 Format: {name of the controller(s) to disable}
449 {Currently supported controllers - "memory"}
450
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 checkreqprot [SELINUX] Set initial checkreqprot flag value.
452 Format: { "0" | "1" }
453 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700454 0 -- check protection applied by kernel (includes
455 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 1 -- check protection requested by application.
457 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700458 Value can be changed at runtime via
459 /selinux/checkreqprot.
460
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100461 cio_ignore= [S390]
462 See Documentation/s390/CommonIO for details.
463
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700464 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700465 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200466 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700467 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200468 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 Format: { pit | tsc | cyclone | pmtmr }
470
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700471 clocksource= [GENERIC_TIME] Override the default clocksource
472 Format: <string>
473 Override the default clocksource and use the clocksource
474 with the name specified.
475 Some clocksource names to choose from, depending on
476 the platform:
477 [all] jiffies (this is the base, fallback clocksource)
478 [ACPI] acpi_pm
479 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
480 pxa_timer,timer3,32k_counter,timer0_1
481 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700482 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700483 scx200_hrt on Geode; cyclone on IBM x440
484 [MIPS] MIPS
485 [PARISC] cr16
486 [S390] tod
487 [SH] SuperH
488 [SPARC64] tick
489 [X86-64] hpet,tsc
490
Andi Kleenac72e782008-01-30 13:33:21 +0100491 clearcpuid=BITNUM [X86]
492 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800493 arch/x86/include/asm/cpufeature.h for the valid bit
494 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100495 stable over kernel options, but the vendor specific
496 ones should be.
497 Also note that user programs calling CPUID directly
498 or using the feature without checking anything
499 will still see it. This just prevents it from
500 being used by the kernel or shown in /proc/cpuinfo.
501 Also note the kernel might malfunction if you disable
502 some critical bits.
503
Robert Jennings14f966e2009-04-15 05:55:32 +0000504 cmo_free_hint= [PPC] Format: { yes | no }
505 Specify whether pages are marked as being inactive
506 when they are freed. This is used in CMO environments
507 to determine OS memory pressure for page stealing by
508 a hypervisor.
509 Default: yes
510
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530511 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100512 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100513 Range: 0 - 8192
514 Default: 64
515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700517 Format:
518 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
520 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 Format: <io>[,<irq>]
522
Randy Dunlapa9913042005-10-23 12:57:11 -0700523 com90xx= [HW,NET]
524 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 Format: <io>[,<irq>[,<memstart>]]
526
527 condev= [HW,S390] console device
528 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700529
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 console= [KNL] Output console device and options.
531
532 tty<n> Use the virtual console device <n>.
533
534 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800535 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800537 the form "bbbbpnf", where "bbbb" is the baud rate,
538 "p" is parity ("n", "o", or "e"), "n" is number of
539 bits, and "f" is flow control ("r" for RTS or
540 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800542 See Documentation/serial-console.txt for more
543 information. See
544 Documentation/networking/netconsole.txt for an
545 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700547 uart[8250],io,<addr>[,options]
548 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 Start an early, polled-mode console on the 8250/16550
550 UART at the specified I/O port or MMIO address,
551 switching to the matching ttyS device later. The
552 options are the same as for ttyS, above.
553
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700554 If the device connected to the port is not a TTY but a braille
555 device, prepend "brl," before the device type, for instance
556 console=brl,ttyS0
557 For now, only VisioBraille is supported.
558
Daniel Mackf324edc2009-06-16 15:33:52 -0700559 consoleblank= [KNL] The console blank (screen saver) timeout in
560 seconds. Defaults to 10*60 = 10mins. A value of 0
561 disables the blank timer.
562
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800563 coredump_filter=
564 [KNL] Change the default value for
565 /proc/<pid>/coredump_filter.
566 See also Documentation/filesystems/proc.txt.
567
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700569 Format:
570 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700572 crashkernel=nn[KMG]@ss[KMG]
573 [KNL] Reserve a chunk of physical memory to
574 hold a kernel to switch to with kexec on panic.
575
Bernhard Wallefb391592007-10-18 23:41:02 -0700576 crashkernel=range1:size1[,range2:size2,...][@offset]
577 [KNL] Same as above, but depends on the memory
578 in the running system. The syntax of range is
579 start-[end] where start and end are both
580 a memory unit (amount[KMG]). See also
581 Documentation/kdump/kdump.txt for a example.
582
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 cs89x0_dma= [HW,NET]
584 Format: <dma>
585
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700588
Randy Dunlapa9913042005-10-23 12:57:11 -0700589 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 See header of drivers/s390/block/dasd_devmap.c.
591
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
596
597 debug [KNL] Enable kernel debugging (events log level).
598
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700599 debug_locks_verbose=
600 [KNL] verbose self-tests
601 Format=<0|1>
602 Print debugging info while doing the locking API
603 self-tests.
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
607
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700608 debug_objects [KNL] Enable object debugging
609
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500610 no_debug_objects
611 [KNL] Disable object debugging
612
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200613 debugpat [X86] Enable PAT debugging
614
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200615 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 Format: <area>[,<node>]
617 See also Documentation/networking/decnet.txt.
618
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700619 default_hugepagesz=
620 [same as hugepagesz=] The size of the default
621 HugeTLB page size. This is the size represented by
622 the legacy /proc/ hugepages APIs, used for SHM, and
623 default size when mounting hugetlbfs filesystems.
624 Defaults to the default architecture's huge page size
625 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700626
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 dhash_entries= [KNL]
628 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 digi= [HW,SERIAL]
631 IO parameters + enable/disable command.
632
633 digiepca= [HW,SERIAL]
634 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000635 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
Brian Haleyb0f83b22010-02-04 13:36:50 -0800637 disable= [IPV6]
638 See Documentation/networking/ipv6.txt.
639
640 disable_ipv6= [IPV6]
641 See Documentation/networking/ipv6.txt.
642
Yinghai Lu95ffa242008-04-29 03:52:33 -0700643 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700644 The kernel tries to adjust MTRR layout from continuous
645 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700646 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700647
Yinghai Lu093af8d2008-01-30 13:33:32 +0100648 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100649 By default the kernel will trim any uncacheable
650 memory out of your available memory pool based on
651 MTRR settings. This parameter disables that behavior,
652 possibly causing your machine to run very slowly.
653
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530654 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700655 Disable PIN 1 of APIC timer
656 Can be useful to work around chipset bugs.
657
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 dmasound= [HW,OSS] Sound subsystem buffers
659
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700660 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
661 this option disables the debugging code at boot.
662
663 dma_debug_entries=<number>
664 This option allows to tune the number of preallocated
665 entries for DMA-API debugging code. One entry is
666 required per DMA-API allocation. Use this if the
667 DMA-API debugging code disables itself because the
668 architectural default is too low.
669
Joerg Roedel1745de52009-05-22 21:49:51 +0200670 dma_debug_driver=<driver_name>
671 With this option the DMA-API debugging driver
672 filter feature can be enabled at boot time. Just
673 pass the driver to filter for as the parameter.
674 The filter can be disabled or changed to another
675 driver later using sysfs.
676
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 dscc4.setup= [NET]
678
679 dtc3181e= [HW,SCSI]
680
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700681 dynamic_printk Enables pr_debug()/dev_dbg() calls if
682 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
683 These can also be switched on/off via
684 <debugfs>/dynamic_printk/modules
685
686 earlycon= [KNL] Output early console device and options.
687 uart[8250],io,<addr>[,options]
688 uart[8250],mmio,<addr>[,options]
689 Start an early, polled-mode console on the 8250/16550
690 UART at the specified I/O port or MMIO address.
691 The options are the same as for ttyS, above.
692
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530693 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 earlyprintk=vga
695 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500696 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500697 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
Randy Dunlapa9913042005-10-23 12:57:11 -0700699 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 takes over.
701
Yinghai Lu5c059172008-07-24 17:29:40 -0700702 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703
704 Currently only ttyS0 and ttyS1 are supported.
705
706 Interaction with the standard serial driver is not
707 very good.
708
709 The VGA output is eventually overwritten by the real
710 console.
711
Jason Wessel97311912010-05-20 21:04:30 -0500712 ekgdboc= [X86,KGDB] Allow early kernel console debugging
713 ekgdboc=kbd
714
715 This is desgined to be used in conjunction with
716 the boot argument: earlyprintk=vga
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 eata= [HW,SCSI]
719
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700721 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 eisa_irq_edge= [PARISC,HW]
724 See header of drivers/parisc/eisa.c.
725
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700726 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700728 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729
730 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800731 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700732 See Documentation/block/as-iosched.txt and
733 Documentation/block/deadline-iosched.txt for details.
734
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530735 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700736 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800737 image elf header. Generally kexec loader will
738 pass this option to capture kernel.
739 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700741 enable_mtrr_cleanup [X86]
742 The kernel tries to adjust MTRR layout from continuous
743 to discrete, to make X server driver able to add WB
744 entry later. This parameter enables that.
745
Randy Dunlapca1eda22009-05-06 16:02:58 -0700746 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700747 Enable PIN 1 of APIC timer
748 Can be useful to work around chipset bugs
749 (in particular on some ATI chipsets).
750 The kernel tries to set a reasonable default.
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 enforcing [SELINUX] Set initial enforcing status.
753 Format: {"0" | "1"}
754 See security/selinux/Kconfig help text.
755 0 -- permissive (log only, no denials).
756 1 -- enforcing (deny and log).
757 Default value is 0.
758 Value can be changed at runtime via /selinux/enforce.
759
Huang Yinga08f82d2010-05-18 14:35:21 +0800760 erst_disable [ACPI]
761 Disable Error Record Serialization Table (ERST)
762 support.
763
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 ether= [HW,NET] Ethernet cards parameters
765 This option is obsoleted by the "netdev=" option, which
766 has equivalent usage. See its documentation for details.
767
Akinobu Mitade1ba092006-12-08 02:39:42 -0800768 failslab=
769 fail_page_alloc=
770 fail_make_request=[KNL]
771 General fault injection mechanism.
772 Format: <interval>,<probability>,<space>,<times>
773 See also /Documentation/fault-injection/.
774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 fd_mcs= [HW,SCSI]
776 See header of drivers/scsi/fd_mcs.c.
777
778 fdomain= [HW,SCSI]
779 See header of drivers/scsi/fdomain.c.
780
781 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000782 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
Alex Chiangf13ae302008-05-08 14:03:23 -0600784 force_pal_cache_flush
785 [IA-64] Avoid check_sal_cache_flush which may hang on
786 buggy SAL_CACHE_FLUSH implementations. Using this
787 parameter will force ia64_sal_cache_flush to call
788 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
789
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100790 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400791 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100792 as early as possible in order to facilitate early
793 boot debugging.
794
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200795 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400796 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200797 If no parameter is passed, ftrace will dump
798 buffers of all CPUs, but if you pass orig_cpu, it will
799 dump only the buffer of the CPU that triggered the
800 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400801
802 ftrace_filter=[function-list]
803 [FTRACE] Limit the functions traced by the function
804 tracer at boot up. function-list is a comma separated
805 list of functions. This list can be changed at run
806 time by the set_ftrace_filter file in the debugfs
807 tracing directory.
808
809 ftrace_notrace=[function-list]
810 [FTRACE] Do not trace the functions specified in
811 function-list. This list can be changed at run time
812 by the set_ftrace_notrace file in the debugfs
813 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100814
Stefan Assmann369bc182009-10-12 22:17:21 +0200815 ftrace_graph_filter=[function-list]
816 [FTRACE] Limit the top level callers functions traced
817 by the function graph tracer at boot up.
818 function-list is a comma separated list of functions
819 that can be changed at run time by the
820 set_graph_function file in the debugfs tracing directory.
821
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 gamecon.map[2|3]=
823 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
824 support via parallel port (up to 5 devices per port)
825 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
826 See also Documentation/input/joystick-parport.txt
827
828 gamma= [HW,DRM]
829
Yinghai Luaaf23042008-01-30 13:33:09 +0100830 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
831 Format: off | on
832 default: on
833
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700834 gcov_persist= [GCOV] When non-zero (default), profiling data for
835 kernel modules is saved and remains accessible via
836 debugfs, even when the module is unloaded/reloaded.
837 When zero, profiling data is discarded and associated
838 debugfs files are removed at module unload time.
839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 gdth= [HW,SCSI]
841 See header of drivers/scsi/gdth.c.
842
843 gpt [EFI] Forces disk with valid GPT signature but
844 invalid Protective MBR to be treated as GPT.
845
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 gvp11= [HW,SCSI]
847
848 hashdist= [KNL,NUMA] Large hashes allocated during boot
849 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700850 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700851 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852
853 hcl= [IA-64] SGI's Hardware Graph compatibility layer
854
855 hd= [EIDE] (E)IDE hard drive subsystem geometry
856 Format: <cyl>,<head>,<sect>
857
Huang Yingea8c0712010-05-18 14:35:15 +0800858 hest_disable [ACPI]
859 Disable Hardware Error Source Table (HEST) support;
860 corresponding firmware-first mode error processing
861 logic will be disabled.
862
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
864 size of <nn>. This works even on boxes that have no
865 highmem otherwise. This also works to reduce highmem
866 size on bigger boxes.
867
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800868 highres= [KNL] Enable/disable high resolution timer mode.
869 Valid parameters: "on", "off"
870 Default: "on"
871
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 hisax= [HW,ISDN]
873 See Documentation/isdn/README.HiSax.
874
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700875 hlt [BUGS=ARM,SH]
876
877 hpet= [X86-32,HPET] option to control HPET usage
878 Format: { enable (default) | disable | force |
879 verbose }
880 disable: disable HPET and use PIT instead
881 force: allow force enabled of undocumented chips (ICH4,
882 VIA, nVidia)
883 verbose: show contents of HPET registers during setup
884
Andi Kleenb4718e62008-07-23 21:27:51 -0700885 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
886 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700887 On x86-64 and powerpc, this option can be specified
888 multiple times interleaved with hugepages= to reserve
889 huge pages of different sizes. Valid pages sizes on
890 x86-64 are 2M (when the CPU supports "pse") and 1G
891 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700892 Note that 1GB pages can only be allocated at boot time
893 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900894
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100895 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
896 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100897 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
898 If specified, z/VM IUCV HVC accepts connections
899 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100900
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700901 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700902 or register an additional I2C bus that is not
903 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700904 Format:
905 <bus_id>,<clkrate>
906
Jiri Kosina36d95732008-10-06 02:51:09 -0400907 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200909 i8042.dumbkbd [HW] Pretend that controller can only read data from
910 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 (Don't attempt to blink the leds)
912 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500913 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400914 i8042.noloop [HW] Disable the AUX Loopback command while probing
915 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 i8042.nomux [HW] Don't check presence of an active multiplexing
917 controller
918 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
919 controllers
920 i8042.panicblink=
921 [HW] Frequency with which keyboard LEDs should blink
922 when kernel panics (default is 0.5 sec)
923 i8042.reset [HW] Reset the controller during init and cleanup
924 i8042.unlock [HW] Unlock (ignore) the keylock
925
926 i810= [HW,DRM]
927
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700928 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
929 indicates that the driver is running on unsupported
930 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
932 does not match list of supported models.
933 i8k.power_status
934 [HW] Report power status in /proc/i8k
935 (disabled by default)
936 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
937 capability is set.
938
939 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
940 See Documentation/mca.txt.
941
942 icn= [HW,ISDN]
943 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
944
David Fries0af80c02009-02-25 20:28:21 +0100945 ide-core.nodma= [HW] (E)IDE subsystem
946 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200947 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
948 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100949 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700951 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
952 Claim all unknown PCI IDE storage controllers.
953
Andi Kleenf039b752007-05-02 19:27:12 +0200954 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800955 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
956 Poll forces a polling idle loop that can slightly
957 improve the performance of waking up a idle CPU, but
958 will use a lot of power and make the system run hot.
959 Not recommended.
960 idle=mwait: On systems which support MONITOR/MWAIT but
961 the kernel chose to not use it because it doesn't save
962 as much power as a normal idle loop, use the
963 MONITOR/MWAIT idle loop anyways. Performance should be
964 the same as idle=poll.
965 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800966 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800967 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700968
Ingo Molnar792908222006-12-06 20:40:51 -0800969 ignore_loglevel [KNL]
970 Ignore loglevel setting - this will print /all/
971 kernel messages to the console. Useful for debugging.
972
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 ihash_entries= [KNL]
974 Set number of hash buckets for inode cache.
975
Mimi Zohar3323eec2009-02-04 09:06:58 -0500976 ima_audit= [IMA]
977 Format: { "0" | "1" }
978 0 -- integrity auditing messages. (Default)
979 1 -- enable informational integrity auditing messages.
980
981 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700982 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500983 default: "sha1"
984
Eric Paris5789ba32009-05-21 15:47:06 -0400985 ima_tcb [IMA]
986 Load a policy which meets the needs of the Trusted
987 Computing Base. This means IMA will measure all
988 programs exec'd, files mmap'd for exec, and all files
989 opened for read by uid=0.
990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 in2000= [HW,SCSI]
992 See header of drivers/scsi/in2000.c.
993
994 init= [KNL]
995 Format: <full_path>
996 Run specified binary instead of /sbin/init as init
997 process.
998
999 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1000 for working out where the kernel is dying during
1001 startup.
1002
1003 initrd= [BOOT] Specify the location of the initial ramdisk
1004
1005 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1006 Format: <irq>
1007
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001008 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001009 on
1010 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001011 off
1012 Disable intel iommu driver.
1013 igfx_off [Default Off]
1014 By default, gfx is mapped as normal device. If a gfx
1015 device has a dedicated DMAR unit, the DMAR unit is
1016 bypassed by not enabling DMAR with this option. In
1017 this case, gfx device will use physical address for
1018 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001019 forcedac [x86_64]
1020 With this option iommu will not optimize to look
1021 for io virtual address below 32 bit forcing dual
1022 address cycle on pci bus for cards supporting greater
1023 than 32 bit addressing. The default is to look
1024 for translation below 32 bit and if not available
1025 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001026 strict [Default Off]
1027 With this option on every unmap_single operation will
1028 result in a hardware IOTLB flush operation as opposed
1029 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001030
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001031 inttest= [IA64]
1032
1033 iomem= Disable strict checking of access to MMIO memory
1034 strict regions from userspace.
1035 relaxed
1036
1037 iommu= [x86]
1038 off
1039 force
1040 noforce
1041 biomerge
1042 panic
1043 nopanic
1044 merge
1045 nomerge
1046 forcesac
1047 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001048 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001049
1050 io7= [HW] IO7 for Marvel based alpha systems
1051 See comment before marvel_specify_io7 in
1052 arch/alpha/kernel/core_marvel.c.
1053
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301054 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001055 0x80
1056 Standard port 0x80 based delay
1057 0xed
1058 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001059 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001060 Simple two microseconds delay
1061 none
1062 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001063
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001065 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066
1067 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001068 See comment before ip2_setup() in
1069 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070
1071 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1072 See header of drivers/scsi/ips.c.
1073
Alan Cox200803d2005-06-28 20:45:18 -07001074 irqfixup [HW]
1075 When an interrupt is not handled search all handlers
1076 for it. Intended to get systems with badly broken
1077 firmware running.
1078
1079 irqpoll [HW]
1080 When an interrupt is not handled search all handlers
1081 for it. Also check all handlers each timer
1082 interrupt. Intended to get systems with badly broken
1083 firmware running.
1084
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001086 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087
1088 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001089 Format:
1090 <cpu number>,...,<cpu number>
1091 or
Li Zefanb225d442008-11-06 12:53:39 -08001092 <cpu number>-<cpu number>
1093 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001094 or a mixture
1095 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 This option can be used to specify one or more CPUs
1098 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001099 algorithms. You can move a process onto or off an
1100 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 <cpu number> begins at 0 and the maximum value is
1102 "number of CPUs in system - 1".
1103
1104 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001105 alternative -- manually setting the CPU mask of all
1106 tasks in the system -- can cause problems and
1107 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
Randy Dunlapa9913042005-10-23 12:57:11 -07001109 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110
1111 js= [HW,JOY] Analog joystick
1112 See Documentation/input/joystick.txt.
1113
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001114 keepinitrd [HW,ARM]
1115
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301116 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001117 specifies the amount of memory usable by the kernel
1118 for non-movable allocations. The requested amount is
1119 spread evenly throughout all nodes in the system. The
1120 remaining memory in each node is used for Movable
1121 pages. In the event, a node is too small to have both
1122 kernelcore and Movable pages, kernelcore pages will
1123 take priority and other nodes will have a larger number
1124 of kernelcore pages. The Movable zone is used for the
1125 allocation of pages that may be reclaimed or moved
1126 by the page migration subsystem. This means that
1127 HugeTLB pages may not be allocated from this zone.
1128 Note that allocations like PTEs-from-HighMem still
1129 use the HighMem zone if it exists, and the Normal
1130 zone if it does not.
1131
Jason Wessel4fe1da42010-05-20 21:04:31 -05001132 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1133 Format: <Controller#>[,poll interval]
1134 The controller # is the number of the ehci usb debug
1135 port as it is probed via PCI. The poll interval is
1136 optional and is the number seconds in between
1137 each poll cycle to the debug port in case you need
1138 the functionality for interrupting the kernel with
1139 gdb or control-c on the dbgp connection. When
1140 not using this parameter you use sysrq-g to break into
1141 the kernel debugger.
1142
Jason Wessel84c08fd2010-05-20 21:04:24 -05001143 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001144 Requires a tty driver that supports console polling,
1145 or a supported polling keyboard driver (non-usb).
1146 Serial only format: <serial_device>[,baud]
1147 keyboard only format: kbd
1148 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001149
Jason Wessel84c08fd2010-05-20 21:04:24 -05001150 kgdbwait [KGDB] Stop kernel execution and enter the
1151 kernel debugger at the earliest opportunity.
1152
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001153 kmac= [MIPS] korina ethernet MAC address.
1154 Configure the RouterBoard 532 series on-chip
1155 Ethernet adapter MAC address.
1156
Catalin Marinas04f70332009-06-11 13:22:39 +01001157 kmemleak= [KNL] Boot-time kmemleak enable/disable
1158 Valid arguments: on, off
1159 Default: on
1160
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301161 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001162 in oops dumps.
1163
Andre Przywarafef07aa2009-07-10 14:20:35 +02001164 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1165 Default is 0 (don't ignore, but inject #GP)
1166
1167 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1168 Default is 1 (enabled)
1169
1170 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1171 Default is 0 (off)
1172
1173 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1174 for all guests.
1175 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1176
1177 kvm-intel.bypass_guest_pf=
1178 [KVM,Intel] Disables bypassing of guest page faults
1179 on Intel chips. Default is 1 (enabled)
1180
1181 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1182 (virtualized MMU) support on capable Intel chips.
1183 Default is 1 (enabled)
1184
1185 kvm-intel.emulate_invalid_guest_state=
1186 [KVM,Intel] Enable emulation of invalid guest states
1187 Default is 0 (disabled)
1188
1189 kvm-intel.flexpriority=
1190 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1191 Default is 1 (enabled)
1192
1193 kvm-intel.unrestricted_guest=
1194 [KVM,Intel] Disable unrestricted guest feature
1195 (virtualized real and unpaged mode) on capable
1196 Intel chips. Default is 1 (enabled)
1197
1198 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1199 feature (tagged TLBs) on capable Intel chips.
1200 Default is 1 (enabled)
1201
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 l2cr= [PPC]
1203
Robert Brosea78bfbf2008-03-29 07:20:23 +11001204 l3cr= [PPC]
1205
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001206 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001207 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301209 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001210 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001211
FD Camifcb71f62008-01-06 19:08:56 +01001212 libata.dma= [LIBATA] DMA control
1213 libata.dma=0 Disable all PATA and SATA DMA
1214 libata.dma=1 PATA and SATA Disk DMA only
1215 libata.dma=2 ATAPI (CDROM) DMA only
1216 libata.dma=4 Compact Flash DMA only
1217 Combinations also work, so libata.dma=3 enables DMA
1218 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001219
1220 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1221 libata.ignore_hpa=0 keep BIOS limits (default)
1222 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001223
Dave Jones78e70c22007-09-27 11:50:13 -04001224 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1225 when set.
1226 Format: <int>
1227
Tejun Heo33267322008-02-13 09:15:09 +09001228 libata.force= [LIBATA] Force configurations. The format is comma
1229 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001230 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001231 matching port, link or device. Basically, it matches
1232 the ATA ID string printed on console by libata. If
1233 the whole ID part is omitted, the last PORT and DEVICE
1234 values are used. If ID hasn't been specified yet, the
1235 configuration applies to all ports, links and devices.
1236
1237 If only DEVICE is omitted, the parameter applies to
1238 the port and all links and devices behind it. DEVICE
1239 number of 0 either selects the first device or the
1240 first fan-out link behind PMP device. It does not
1241 select the host link. DEVICE number of 15 selects the
1242 host link and device attached to it.
1243
1244 The VAL specifies the configuration to force. As long
1245 as there's no ambiguity shortcut notation is allowed.
1246 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1247 The following configurations can be forced.
1248
1249 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1250 Any ID with matching PORT is used.
1251
1252 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1253
1254 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1255 udma[/][16,25,33,44,66,100,133] notation is also
1256 allowed.
1257
1258 * [no]ncq: Turn on or off NCQ.
1259
Tejun Heo05944bd2008-08-13 20:19:09 +09001260 * nohrst, nosrst, norst: suppress hard, soft
1261 and both resets.
1262
Tejun Heo43c9c592010-05-23 12:59:11 +02001263 * dump_id: dump IDENTIFY data.
1264
Tejun Heo33267322008-02-13 09:15:09 +09001265 If there are multiple matching configurations changing
1266 the same attribute, the last one is used.
1267
Randy Dunlap7c4be252009-01-06 14:42:44 -08001268 lmb=debug [KNL] Enable lmb debug messages.
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001271 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001273 lockd.nlm_grace_period=P [NFS] Assign grace period.
1274 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001276 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1277 Format: <integer>
1278
1279 lockd.nlm_timeout=T [NFS] Assign timeout value.
1280 Format: <integer>
1281
1282 lockd.nlm_udpport=M [NFS] Assign UDP port.
1283 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
1285 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1286 Format: <irq>
1287
1288 loglevel= All Kernel Messages with a loglevel smaller than the
1289 console loglevel will be printed to the console. It can
1290 also be changed with klogd or other programs. The
1291 loglevels are defined as follows:
1292
1293 0 (KERN_EMERG) system is unusable
1294 1 (KERN_ALERT) action must be taken immediately
1295 2 (KERN_CRIT) critical conditions
1296 3 (KERN_ERR) error conditions
1297 4 (KERN_WARNING) warning conditions
1298 5 (KERN_NOTICE) normal but significant condition
1299 6 (KERN_INFO) informational
1300 7 (KERN_DEBUG) debug-level messages
1301
1302 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001303 Format: { n | nk | nM }
1304 n must be a power of two. The default size
1305 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
Randy Dunlapaccaa242007-10-16 01:29:37 -07001307 logo.nologo [FB] Disables display of the built-in Linux logo.
1308 This may be used to provide more screen space for
1309 kernel log messages and is useful when debugging
1310 kernel boot problems.
1311
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 lp=0 [LP] Specify parallel ports to use, e.g,
1313 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1314 lp=reset first parallel port). 'lp=0' disables the
1315 lp=auto printer driver. 'lp=reset' (which can be
1316 specified in addition to the ports) causes
1317 attached printers to be reset. Using
1318 lp=port1,port2,... specifies the parallel ports
1319 to associate lp devices with, starting with
1320 lp0. A port specification may be 'none' to skip
1321 that lp device, or a parport name such as
1322 'parport0'. Specifying 'lp=auto' instead of a
1323 port specification list means that device IDs
1324 from each port should be examined, to see if
1325 an IEEE 1284-compliant printer is attached; if
1326 so, the driver will manage that printer.
1327 See also header of drivers/char/lp.c.
1328
1329 lpj=n [KNL]
1330 Sets loops_per_jiffy to given constant, thus avoiding
1331 time-consuming boot-time autodetection (up to 250 ms per
1332 CPU). 0 enables autodetection (default). To determine
1333 the correct value for your kernel, boot with normal
1334 autodetection and see what value is printed. Note that
1335 on SMP systems the preset will be applied to all CPUs,
1336 which is likely to cause problems if your CPUs need
1337 significantly divergent settings. An incorrect value
1338 will cause delays in the kernel to be wrong, leading to
1339 unpredictable I/O errors and other breakage. Although
1340 unlikely, in the extreme case this might damage your
1341 hardware.
1342
1343 ltpc= [NET]
1344 Format: <io>,<irq>,<dma>
1345
Randy Dunlapa9913042005-10-23 12:57:11 -07001346 mac5380= [HW,SCSI] Format:
1347 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348
Randy Dunlapa9913042005-10-23 12:57:11 -07001349 machvec= [IA64] Force the use of a particular machine-vector
1350 (machvec) in a generic kernel.
1351 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
Wu Zhangjin3209e702009-07-02 23:27:12 +08001353 machtype= [Loongson] Share the same kernel image file between different
1354 yeeloong laptop.
1355 Example: machtype=lemote-yeeloong-2f-7inch
1356
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001357 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1358 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359
1360 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001361 should make use of. maxcpus=n : n >= 0 limits the
1362 kernel to using 'n' processors. n=0 is a special case,
1363 it is equivalent to "nosmp", which also disables
1364 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001366 max_loop= [LOOP] Maximum number of loopback devices that can
1367 be mounted
1368 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001369
Randy Dunlapa9913042005-10-23 12:57:11 -07001370 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 Should be between 1 and 2^32-1.
1372
1373 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001374 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 Should be between 1 and 16384.
1376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 mcatest= [IA-64]
1378
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001379 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
Uwe Hermann71cced62008-10-20 09:32:21 -07001381 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001382
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 md= [HW] RAID subsystems devices and level
1384 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 mdacon= [MDA]
1387 Format: <first>,<last>
1388 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1391 Amount of memory to be used when the kernel is not able
1392 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001393 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 address space collisions. Without memmap= PCI devices
1395 could be placed at addresses belonging to unused RAM.
1396
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001397 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 memory.
1399
Paul Mundt6902aa82008-09-21 17:14:42 +09001400 memchunk=nn[KMG]
1401 [KNL,SH] Allow user to override the default size for
1402 per-device physically contiguous DMA buffers.
1403
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301404 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 E820 memory map, as specified by the user.
1406 Such memmap=exactmap lines can be constructed based on
1407 BIOS output or other requirements. See the memmap=nn@ss
1408 option description.
1409
1410 memmap=nn[KMG]@ss[KMG]
1411 [KNL] Force usage of a specific region of memory
1412 Region of memory to be used, from ss to ss+nn.
1413
1414 memmap=nn[KMG]#ss[KMG]
1415 [KNL,ACPI] Mark specific memory as ACPI data.
1416 Region of memory to be used, from ss to ss+nn.
1417
1418 memmap=nn[KMG]$ss[KMG]
1419 [KNL,ACPI] Mark specific memory as reserved.
1420 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001421 Example: Exclude memory from 0x18690000-0x1869ffff
1422 memmap=64K$0x18690000
1423 or
1424 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001426 memory_corruption_check=0/1 [X86]
1427 Some BIOSes seem to corrupt the first 64k of
1428 memory when doing things like suspend/resume.
1429 Setting this option will scan the memory
1430 looking for corruption. Enabling this will
1431 both detect corruption and prevent the kernel
1432 from using the memory being corrupted.
1433 However, its intended as a diagnostic tool; if
1434 repeatable BIOS-originated corruption always
1435 affects the same memory, you can use memmap=
1436 to prevent the kernel from using that memory.
1437
1438 memory_corruption_check_size=size [X86]
1439 By default it checks for corruption in the low
1440 64k, making this memory unavailable for normal
1441 use. Use this parameter to scan for
1442 corruption in more or less memory.
1443
1444 memory_corruption_check_period=seconds [X86]
1445 By default it checks for corruption every 60
1446 seconds. Use this parameter to check at some
1447 other rate. 0 disables periodic checking.
1448
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001449 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001450 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001451 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001452 Specifies the number of memtest passes to be
1453 performed. Each pass selects another test
1454 pattern from a given set of patterns. Memtest
1455 fills the memory with this pattern, validates
1456 memory contents and reserves bad memory
1457 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001458
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 meye.*= [HW] Set MotionEye Camera parameters
1460 See Documentation/video4linux/meye.txt.
1461
Andres Salomon8f368812007-10-12 23:04:06 +02001462 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1463 Multi-Function General Purpose Timers on AMD Geode
1464 platforms.
1465
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001466 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1467 the BIOS has incorrectly applied a workaround. TinyBIOS
1468 version 0.98 is known to be affected, 0.99 fixes the
1469 problem by letting the user disable the workaround.
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 mga= [HW,DRM]
1472
Randy Dunlap1c207f92008-11-19 15:36:16 -08001473 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1474 physical address is ignored.
1475
Michel Pollet39f45d72009-05-20 11:10:31 +01001476 mini2440= [ARM,HW,KNL]
1477 Format:[0..2][b][c][t]
1478 Default: "0tb"
1479 MINI2440 configuration specification:
1480 0 - The attached screen is the 3.5" TFT
1481 1 - The attached screen is the 7" TFT
1482 2 - The VGA Shield is attached (1024x768)
1483 Leaving out the screen size parameter will not load
1484 the TFT driver, and the framebuffer will be left
1485 unconfigured.
1486 b - Enable backlight. The TFT backlight pin will be
1487 linked to the kernel VESA blanking code and a GPIO
1488 LED. This parameter is not necessary when using the
1489 VGA shield.
1490 c - Enable the s3c camera interface.
1491 t - Reserved for enabling touchscreen support. The
1492 touchscreen support is not enabled in the mainstream
1493 kernel as of 2.6.30, a preliminary port can be found
1494 in the "bleeding edge" mini2440 support kernel at
1495 http://repo.or.cz/w/linux-2.6/mini2440.git
1496
Mel Gorman6b74ab92008-07-23 21:26:49 -07001497 mminit_loglevel=
1498 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1499 parameter allows control of the logging verbosity for
1500 the additional memory initialisation checks. A value
1501 of 0 disables mminit logging and a level of 4 will
1502 log everything. Information is printed at KERN_DEBUG
1503 so loglevel=8 may also need to be specified.
1504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 mousedev.tap_time=
1506 [MOUSE] Maximum time between finger touching and
1507 leaving touchpad surface for touch to be considered
1508 a tap and be reported as a left button click (for
1509 touchpads working in absolute mode only).
1510 Format: <msecs>
1511 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1512 reporting absolute coordinates, such as tablets
1513 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1514 reporting absolute coordinates, such as tablets
1515
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301516 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001517 is similar to kernelcore except it specifies the
1518 amount of memory used for migratable allocations.
1519 If both kernelcore and movablecore is specified,
1520 then kernelcore will be at *least* the specified
1521 value but may be more. If movablecore on its own
1522 is specified, the administrator must be careful
1523 that the amount of memory usable for all allocations
1524 is not too small.
1525
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 mpu401= [HW,OSS]
1527 Format: <io>,<irq>
1528
1529 MTD_Partition= [MTD]
1530 Format: <name>,<region-number>,<size>,<offset>
1531
Randy Dunlapa9913042005-10-23 12:57:11 -07001532 MTD_Region= [MTD] Format:
1533 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
1535 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001536 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001538 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1539
1540 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1541
1542 boundary - index of last SLC block on Flex-OneNAND.
1543 The remaining blocks are configured as MLC blocks.
1544 lock - Configure if Flex-OneNAND boundary should be locked.
1545 Once locked, the boundary cannot be changed.
1546 1 indicates lock status, 0 indicates unlock status.
1547
Ben Dooks9db829f2008-07-03 11:24:29 +01001548 mtdset= [ARM]
1549 ARM/S3C2412 JIVE boot control
1550
1551 See arch/arm/mach-s3c2412/mach-jive.c
1552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001554 [HW] Make the MicroTouch USB driver use raw coordinates
1555 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001557 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001558 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001559 that could hold holes aka. UC entries.
1560
1561 mtrr_gran_size=nn[KMG] [X86]
1562 Used for mtrr cleanup. It is granularity of mtrr block.
1563 Default is 1.
1564 Large value could prevent small alignment from
1565 using up MTRRs.
1566
1567 mtrr_spare_reg_nr=n [X86]
1568 Format: <integer>
1569 Range: 0,7 : spare reg number
1570 Default : 1
1571 Used for mtrr cleanup. It is spare mtrr entries number.
1572 Set to 2 or more if your graphical card needs more.
1573
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1575
1576 NCR_D700= [HW,SCSI]
1577 See header of drivers/scsi/NCR_D700.c.
1578
1579 ncr5380= [HW,SCSI]
1580
1581 ncr53c400= [HW,SCSI]
1582
1583 ncr53c400a= [HW,SCSI]
1584
1585 ncr53c406a= [HW,SCSI]
1586
1587 ncr53c8xx= [HW,SCSI]
1588
1589 netdev= [NET] Network devices parameters
1590 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1591 Note that mem_start is often overloaded to mean
1592 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001593 This usage is only documented in each driver source
1594 file if at all.
1595
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001596 nf_conntrack.acct=
1597 [NETFILTER] Enable connection tracking flow accounting
1598 0 to disable accounting
1599 1 to enable accounting
1600 Default value depends on CONFIG_NF_CT_ACCT that is
1601 going to be removed in 2.6.29.
1602
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001604 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605
1606 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001607 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
Trond Myklebusta72b4422006-01-03 09:55:41 +01001609 nfs.callback_tcpport=
1610 [NFS] set the TCP port on which the NFSv4 callback
1611 channel should listen.
1612
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001613 nfs.cache_getent=
1614 [NFS] sets the pathname to the program which is used
1615 to update the NFS client cache entries.
1616
1617 nfs.cache_getent_timeout=
1618 [NFS] sets the timeout after which an attempt to
1619 update a cache entry is deemed to have failed.
1620
Trond Myklebust58df0952006-01-03 09:55:57 +01001621 nfs.idmap_cache_timeout=
1622 [NFS] set the maximum lifetime for idmapper cache
1623 entries.
1624
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001625 nfs.enable_ino64=
1626 [NFS] enable 64-bit inode numbers.
1627 If zero, the NFS client will fake up a 32-bit inode
1628 number for the readdir() and stat() syscalls instead
1629 of returning the full 64-bit number.
1630 The default is to return 64-bit inode numbers.
1631
Paul Mundt1e1030d2009-09-01 17:38:32 +09001632 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001633 when a NMI is triggered.
1634 Format: [state][,regs][,debounce][,die]
1635
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301636 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001637 Format: [panic,][num]
1638 Valid num: 0,1,2
1639 0 - turn nmi_watchdog off
1640 1 - use the IO-APIC timer for the NMI watchdog
1641 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001642 a performance counter. Note: This will use one
1643 performance counter and the local APIC's performance
1644 vector.
1645 When panic is specified, panic when an NMI watchdog
1646 timeout occurs.
1647 This is useful when you use a panic=... timeout and
1648 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001649 Instead of 1 and 2 it is possible to use the following
1650 symbolic names: lapic and ioapic
1651 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652
Anton Vorontsovbff38772009-07-08 11:10:56 -07001653 netpoll.carrier_timeout=
1654 [NET] Specifies amount of time (in seconds) that
1655 netpoll should wait for a carrier. By default netpoll
1656 waits 4 seconds.
1657
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001658 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 emulation library even if a 387 maths coprocessor
1660 is present.
1661
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001662 no_console_suspend
1663 [HW] Never suspend the console
1664 Disable suspending of consoles during suspend and
1665 hibernate operations. Once disabled, debugging
1666 messages can reach various consoles while the rest
1667 of the system is being put to sleep (ie, while
1668 debugging driver suspend/resume hooks). This may
1669 not work reliably with all consoles, but is known
1670 to work with serial and VGA consoles.
1671
Christoph Lameterc1aee212007-05-31 00:40:47 -07001672 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1673 caches in the slab allocator. Saves per-node memory,
1674 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001675
Randy Dunlapa9913042005-10-23 12:57:11 -07001676 noalign [KNL,ARM]
1677
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 noapic [SMP,APIC] Tells the kernel to not make use of any
1679 IOAPICs that may be present in the system.
1680
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 nobats [PPC] Do not use BATs for mapping kernel lowmem
1682 on "Classic" PPC cores.
1683
1684 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001685
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001686 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1687
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001688 nodelayacct [KNL] Disable per-task delay accounting
1689
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1691
Paul Mundt6902aa82008-09-21 17:14:42 +09001692 nodsp [SH] Disable hardware DSP at boot time.
1693
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301694 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001695
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 noexec [IA-64]
1697
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301698 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001699 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001701 noexec=off: disable non-executable mappings
1702
1703 noexec32 [X86-64]
1704 This affects only 32-bit executables.
1705 noexec32=on: enable non-executable mappings (default)
1706 read doesn't imply executable mappings
1707 noexec32=off: disable non-executable mappings
1708 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709
Paul Mundt6902aa82008-09-21 17:14:42 +09001710 nofpu [SH] Disable hardware FPU at boot time.
1711
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001712 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001713 register save and restore. The kernel will only save
1714 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715
Suresh Siddha0c752a92009-05-22 12:17:45 -07001716 noxsave [BUGS=X86] Disables x86 extended register state save
1717 and restore using xsave. The kernel will fallback to
1718 enabling legacy floating-point and sse state.
1719
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001720 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1721 wfi(ARM) instruction doesn't work correctly and not to
1722 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001723
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001724 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 instruction doesn't work correctly and not to
1726 use it.
1727
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001728 no_file_caps Tells the kernel not to honor file capabilities. The
1729 only way then for a file to be executed with privilege
1730 is to be setuid root or executed by root.
1731
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 nohalt [IA-64] Tells the kernel not to use the power saving
1733 function PAL_HALT_LIGHT when idle. This increases
1734 power-consumption. On the positive side, it reduces
1735 interrupt wake-up latency, which may improve performance
1736 in certain environments such as networked servers or
1737 real-time systems.
1738
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001739 nohz= [KNL] Boottime enable/disable dynamic ticks
1740 Valid arguments: on, off
1741 Default: on
1742
Paul Mundteeee7852009-04-02 12:31:16 +09001743 noiotrap [SH] Disables trapped I/O port accesses.
1744
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001745 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 disable unhandled interrupt sources.
1747
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301748 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001749 broken timer IRQ sources.
1750
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 noisapnp [ISAPNP] Disables ISA PnP code.
1752
1753 noinitrd [RAM] Tells the kernel not to load any configured
1754 initial RAM disk.
1755
Weidong Han03ea8152009-04-17 16:42:15 +08001756 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1757 remapping.
1758
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 nointroute [IA-64]
1760
Tony Luck0aa366f2007-07-20 11:22:30 -07001761 nojitter [IA64] Disables jitter checking for ITC timers.
1762
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001763 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001765 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001766
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 noltlbs [PPC] Do not use large page/tlb entries for kernel
1768 lowmem mapping on PPC40x.
1769
Horms312f1f02006-02-22 09:57:55 +09001770 nomca [IA-64] Disable machine check abort handling
1771
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001772 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001773
Andres Salomon83d73842007-10-12 23:04:06 +02001774 nomfgpt [X86-32] Disable Multi-Function General Purpose
1775 Timer usage (for AMD Geode machines).
1776
Jiri Kosina016ddd92010-01-18 17:05:40 +01001777 nopat [X86] Disable PAT (page attribute table extension of
1778 pagetables) support.
1779
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001780 norandmaps Don't use address space randomization. Equivalent to
1781 echo 0 > /proc/sys/kernel/randomize_va_space
1782
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001783 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001784
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001785 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001786 with UP alternatives
1787
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 noresidual [PPC] Don't use residual data on PReP machines.
1789
Randy Dunlapa9913042005-10-23 12:57:11 -07001790 noresume [SWSUSP] Disables resume and restores original swap
1791 space.
1792
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 no-scroll [VGA] Disables scrollback.
1794 This is required for the Braillex ib80-piezo Braille
1795 reader made by F.H. Papenmeier (Germany).
1796
1797 nosbagart [IA-64]
1798
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001799 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001800
Len Brown61ec7562007-08-16 03:34:22 -04001801 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1802 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803
Dave Jones97842212007-07-15 23:41:05 -07001804 nosoftlockup [KNL] Disable the soft-lockup detector.
1805
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001806 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001807 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001808
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809 nosync [HW,M68K] Disables sync negotiation for all devices.
1810
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001811 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812
1813 nousb [USB] Disable the USB subsystem
1814
1815 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001816
Weidong Han2b2fd872009-04-17 16:42:12 +08001817 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1818
Fenghua Yua6c75b862008-03-14 13:57:08 -07001819 nptcg= [IA64] Override max number of concurrent global TLB
1820 purges which is reported from either PAL_VM_SUMMARY or
1821 SAL PALO.
1822
Yinghai Lu2b633e32010-02-10 01:20:37 -08001823 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1824 could support. nr_cpus=n : n >= 1 limits the kernel to
1825 supporting 'n' processors. Later in runtime you can not
1826 use hotplug cpu feature to put more cpu back to online.
1827 just like you compile the kernel NR_CPUS=n
1828
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001829 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1830
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001831 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1832 one of ['zone', 'node', 'default'] can be specified
1833 This can be set from sysctl after boot.
1834 See Documentation/sysctl/vm.txt for details.
1835
Randy Dunlap7c4be252009-01-06 14:42:44 -08001836 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1837 See Documentation/debugging-via-ohci1394.txt for more
1838 info.
1839
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001840 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1841 Rather than timing out after 20 ms if an EC
1842 command is not properly ACKed, override the length
1843 of the timeout. We have interrupts disabled while
1844 waiting for the ACK, so if this is set too high
1845 interrupts *may* be lost!
1846
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001847 omap_mux= [OMAP] Override bootloader pin multiplexing.
1848 Format: <mux_mode0.mode_name=value>...
1849 For example, to override I2C bus2:
1850 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1851
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 opl3= [HW,OSS]
1853 Format: <io>
1854
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855 oprofile.timer= [HW]
1856 Use timer interrupt instead of performance counters
1857
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001858 oprofile.cpu_type= Force an oprofile cpu type
1859 This might be useful if you have an older oprofile
1860 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001861 Format: { arch_perfmon }
1862 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001863 perfmon on Intel CPUs instead of the
1864 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001865
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 osst= [HW,SCSI] SCSI Tape Driver
1867 Format: <buffer_size>,<write_threshold>
1868 See also Documentation/scsi/st.txt.
1869
1870 panic= [KNL] Kernel behaviour on panic
1871 Format: <timeout>
1872
1873 parkbd.port= [HW] Parallel port number the keyboard adapter is
1874 connected to, default is 0.
1875 Format: <parport#>
1876 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1877 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001878 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879
Randy Dunlapa9913042005-10-23 12:57:11 -07001880 parport= [HW,PPT] Specify parallel ports. 0 disables.
1881 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1882 Use 'auto' to force the driver to use any
1883 IRQ/DMA settings detected (the default is to
1884 ignore detected IRQ/DMA settings because of
1885 possible conflicts). You can specify the base
1886 address, IRQ, and DMA settings; IRQ and DMA
1887 should be numbers, or 'auto' (for using detected
1888 settings on that particular port), or 'nofifo'
1889 (to avoid using a FIFO even if it is detected).
1890 Parallel ports are assigned in the order they
1891 are specified on the command line, starting
1892 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
Randy Dunlapa9913042005-10-23 12:57:11 -07001894 parport_init_mode= [HW,PPT]
1895 Configure VIA parallel port to operate in
1896 a specific mode. This is necessary on Pegasos
1897 computer where firmware has no options for setting
1898 up parallel port mode and sets it to spp.
1899 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900 Format: [spp|ps2|epp|ecp|ecpepp]
1901
Randy Dunlapa9913042005-10-23 12:57:11 -07001902 pas2= [HW,OSS] Format:
1903 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1904
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 pas16= [HW,SCSI]
1906 See header of drivers/scsi/pas16.c.
1907
Andrew Mortondd287792006-03-23 03:00:57 -08001908 pause_on_oops=
1909 Halt all CPUs after the first oops has been printed for
1910 the specified number of seconds. This is to be used if
1911 your oopses keep scrolling off the screen.
1912
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 pcbit= [HW,ISDN]
1914
1915 pcd. [PARIDE]
1916 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001917 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918
Randy Dunlapa9913042005-10-23 12:57:11 -07001919 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001920 earlydump [X86] dump PCI config space before the kernel
1921 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001922 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001923 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001924 the hardware directly. Use this if your machine
1925 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001926 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001927 hardware access methods are allowed. Use this
1928 if you experience crashes upon bootup and you
1929 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001930 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001931 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001932 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001933 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001934 noaer [PCIE] If the PCIEAER kernel config parameter is
1935 enabled, this kernel boot option can be used to
1936 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001937 nodomains [PCI] Disable support for multiple PCI
1938 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301939 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001940 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001941 check_enable_amd_mmconf [X86] check for and enable
1942 properly configured MMIO access to PCI
1943 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001944 nomsi [MSI] If the PCI_MSI kernel config parameter is
1945 enabled, this kernel boot option can be used to
1946 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001947 noioapicquirk [APIC] Disable all boot interrupt quirks.
1948 Safety option to keep boot IRQs enabled. This
1949 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001950 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1951 primary IO-APIC for bridges that cannot disable
1952 boot IRQs. This fixes a source of spurious IRQs
1953 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001954 noioapicreroute [APIC] Disable workaround that uses the
1955 boot IRQ equivalent of an IRQ that connects to
1956 a chipset where boot IRQs cannot be disabled.
1957 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001958 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001959 routing table. These calls are known to be buggy
1960 on several machines and they hang the machine
1961 when used, but on other computers it's the only
1962 way to get the interrupt routing table. Try
1963 this option if the kernel is unable to allocate
1964 IRQs or discover secondary PCI buses on your
1965 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001966 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001967 Use with caution as certain devices share
1968 address decoders between ROMs and other
1969 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001970 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001971 expansion ROMs that do not already have
1972 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001973 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001974 assigned automatically to PCI devices. You can
1975 make the kernel exclude IRQs of your ISA cards
1976 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001977 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001978 of the PIRQ table (normally generated
1979 by the BIOS) if it is outside the
1980 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001981 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001982 useful if the kernel is unable to find your
1983 secondary buses and you want to tell it
1984 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001985 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001986 numbers ourselves, overriding
1987 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001988 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001989 in the BIOS $PIR table. This is needed on
1990 some systems with broken BIOSes, notably
1991 some HP Pavilion N5400 and Omnibook XE3
1992 notebooks. This will have no effect if ACPI
1993 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001994 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001995 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001996 use_crs [X86] Use PCI host bridge window information
1997 from ACPI. On BIOSes from 2008 or later, this
1998 is enabled by default. If you need to use this,
1999 please report a bug.
2000 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2001 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002002 routeirq Do IRQ routing for all PCI devices.
2003 This is normally done in pci_enable_device(),
2004 so this option is a temporary workaround
2005 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002006 skip_isa_align [X86] do not align io start addr, so can
2007 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002008 firmware [ARM] Do not re-enumerate the bus but instead
2009 just use the configuration from the
2010 bootloader. This is currently used on
2011 IXP2000 systems where the bus has to be
2012 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002013 noearly [X86] Don't do any early type 1 scanning.
2014 This might help on some broken boards which
2015 machine check when some devices' config space
2016 is read. But various workarounds are disabled
2017 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002018 bfsort Sort PCI devices into breadth-first order.
2019 This sorting is done to get a device
2020 order compatible with older (<= 2.4) kernels.
2021 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002022 cbiosize=nn[KMG] The fixed amount of bus space which is
2023 reserved for the CardBus bridge's IO window.
2024 The default value is 256 bytes.
2025 cbmemsize=nn[KMG] The fixed amount of bus space which is
2026 reserved for the CardBus bridge's memory
2027 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002028 resource_alignment=
2029 Format:
2030 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2031 Specifies alignment and device to reassign
2032 aligned memory resources.
2033 If <order of align> is not specified,
2034 PAGE_SIZE is used as alignment.
2035 PCI-PCI bridge can be specified, if resource
2036 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002037 ecrc= Enable/disable PCIe ECRC (transaction layer
2038 end-to-end CRC checking).
2039 bios: Use BIOS/firmware settings. This is the
2040 the default.
2041 off: Turn ECRC off
2042 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002043
Chuck Ebberte5665a42008-09-24 20:40:34 -04002044 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2045 Management.
2046 off Disable ASPM.
2047 force Enable ASPM even on devices that claim not to support it.
2048 WARNING: Forcing ASPM on may cause system lockups.
2049
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002050 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2051 off Do not use native PCIe PME signaling.
2052 force Use native PCIe PME signaling even if the BIOS refuses
2053 to allow the kernel to control the relevant PCIe config
2054 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002055 nomsi Do not use MSI for native PCIe PME signaling (this makes
2056 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002057
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 pcmv= [HW,PCMCIA] BadgePAD 4
2059
2060 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002061 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062
2063 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2064 boot time.
2065 Format: { 0 | 1 }
2066 See arch/parisc/kernel/pdc_chassis.c
2067
Tejun Heof58dc012009-08-14 15:00:50 +09002068 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002069 Currently supported values are "embed" and "page".
2070 Archs may support subset or none of the selections.
2071 See comments in mm/percpu.c for details on each
2072 allocator. This parameter is primarily for debugging
2073 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002074
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002076 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077
2078 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002079 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
2081 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002082 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
2084 plip= [PPT,NET] Parallel port network link
2085 Format: { parport<nr> | timid | 0 }
2086 See also Documentation/parport.txt.
2087
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002088 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2089 Override pmtimer IOPort with a hex value.
2090 e.g. pmtmr=0x508
2091
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002092 pnp.debug [PNP]
2093 Enable PNP debug messages. This depends on the
2094 CONFIG_PNP_DEBUG_MESSAGES option.
2095
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096 pnpacpi= [ACPI]
2097 { off }
2098
2099 pnpbios= [ISAPNP]
2100 { on | off | curr | res | no-curr | no-res }
2101
2102 pnp_reserve_irq=
2103 [ISAPNP] Exclude IRQs for the autoconfiguration
2104
2105 pnp_reserve_dma=
2106 [ISAPNP] Exclude DMAs for the autoconfiguration
2107
2108 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002109 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110
2111 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002112 [ISAPNP] Exclude memory regions for the
2113 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114 Ranges are in pairs (memory base and size).
2115
Randy Dunlap4af94f32009-04-17 18:30:28 -07002116 ports= [IP_VS_FTP] IPVS ftp helper module
2117 Default is 21.
2118 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2119 may be specified.
2120 Format: <port>,<port>....
2121
Ingo Molnar45807a12007-07-15 23:40:10 -07002122 print-fatal-signals=
2123 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002124
2125 If enabled, warn about various signal handling
2126 related application anomalies: too many signals,
2127 too many POSIX.1 timers, fatal signals causing a
2128 coredump - etc.
2129
2130 If you hit the warning due to signal overflow,
2131 you might want to try "ulimit -i unlimited".
2132
Ingo Molnar45807a12007-07-15 23:40:10 -07002133 default: off.
2134
Randy Dunlape84845c2007-07-15 23:40:25 -07002135 printk.time= Show timing data prefixed to each printk message line
2136 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2137
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002138 processor.max_cstate= [HW,ACPI]
2139 Limit processor to maximum C-state
2140 max_cstate=9 overrides any DMI blacklist limit.
2141
2142 processor.nocst [HW,ACPI]
2143 Ignore the _CST method to determine C-states,
2144 instead using the legacy FADT method
2145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002147 Format: [schedule,]<number>
2148 Param: "schedule" - profile schedule points.
2149 Param: <number> - step/bucket size as a power of 2 for
2150 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002151 Param: "sleep" - profile D-state sleeping (millisecs).
2152 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002153 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2156 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002157 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158
Randy Dunlapa9913042005-10-23 12:57:11 -07002159 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2160 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2162 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002163 psmouse.resetafter= [HW,MOUSE]
2164 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 (0 = never).
2166 psmouse.resolution=
2167 [HW,MOUSE] Set desired mouse resolution, in dpi.
2168 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002169 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 0 = disabled, 1 = enabled (default).
2171
2172 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002173 Format:
2174 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175
2176 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002177 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178
Kay Sieversdc8c8582007-08-15 12:25:38 +02002179 pty.legacy_count=
2180 [KNL] Number of legacy pty's. Overwrites compiled-in
2181 default number.
2182
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002183 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002184
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 r128= [HW,DRM]
2186
2187 raid= [HW,RAID]
2188 See Documentation/md.txt.
2189
Randy Dunlapa9913042005-10-23 12:57:11 -07002190 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002191 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002192
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002194 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002196 rcupdate.blimit= [KNL,BOOT]
2197 Set maximum number of finished RCU callbacks to process
2198 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002199
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002200 rcupdate.qhimark= [KNL,BOOT]
2201 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002202 RCU callbacks over which batch limiting is disabled.
2203
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002204 rcupdate.qlowmark= [KNL,BOOT]
2205 Set threshold of queued RCU callbacks below which
2206 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002207
Olof Johanssonffdfc402005-09-06 15:17:19 -07002208 rdinit= [KNL]
2209 Format: <full_path>
2210 Run specified binary instead of /init from the ramdisk,
2211 used for early userspace startup. See initrd.
2212
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002213 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002215 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216
Paul Jackson46b6d942008-07-04 10:00:09 -07002217 relax_domain_level=
2218 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002219 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002220
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2222
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002223 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002224 Format: nn[KMG]
2225 Reserves a hole at the top of the kernel virtual
2226 address space.
2227
Vivek Goyal7e962872006-09-27 01:50:44 -07002228 reset_devices [KNL] Force drivers to reset the underlying device
2229 during initialization.
2230
Randy Dunlapa9913042005-10-23 12:57:11 -07002231 resume= [SWSUSP]
2232 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002233
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002234 resume_offset= [SWSUSP]
2235 Specify the offset from the beginning of the partition
2236 given by "resume=" at which the swap header is located,
2237 in <PAGE_SIZE> units (needed only for swap files).
2238 See Documentation/power/swsusp-and-swap-files.txt
2239
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002240 retain_initrd [RAM] Keep initrd memory after extraction
2241
Linus Torvalds1da177e2005-04-16 15:20:36 -07002242 rhash_entries= [KNL,NET]
2243 Set number of hash buckets for route cache
2244
2245 riscom8= [HW,SERIAL]
2246 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2247
2248 ro [KNL] Mount root device read-only on boot
2249
2250 root= [KNL] Root filesystem
2251
2252 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2253 mount the root filesystem
2254
2255 rootflags= [KNL] Set root filesystem mount option string
2256
2257 rootfstype= [KNL] Set root filesystem type
2258
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002259 rootwait [KNL] Wait (indefinitely) for root device to show up.
2260 Useful for devices that are detected asynchronously
2261 (e.g. USB and MMC devices).
2262
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 rw [KNL] Mount root device read-write on boot
2264
2265 S [KNL] Run init in single mode
2266
2267 sa1100ir [NET]
2268 See drivers/net/irda/sa1100_ir.c.
2269
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002271
Mike Travisf6630112009-11-17 18:22:15 -06002272 sched_debug [KNL] Enables verbose scheduler debug messages.
2273
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 scsi_debug_*= [SCSI]
2275 See drivers/scsi/scsi_debug.c.
2276
2277 scsi_default_dev_flags=
2278 [SCSI] SCSI default device flags
2279 Format: <integer>
2280
2281 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2282 Format: <vendor>:<model>:<flags>
2283 (flags are integer value)
2284
Randy Dunlap6af66322007-11-14 16:52:25 -08002285 scsi_logging_level= [SCSI] a bit mask of logging levels
2286 See drivers/scsi/scsi_logging.h for bits. Also
2287 settable via sysctl at dev.scsi.logging_level
2288 (/proc/sys/dev/scsi/logging_level).
2289 There is also a nice 'scsi_logging_level' script in the
2290 S390-tools package, available for download at
2291 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002293 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2294 discovered. async scans them in kernel threads,
2295 allowing boot to proceed. none ignores them, expecting
2296 user space to do the scan.
2297
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002298 security= [SECURITY] Choose a security module to enable at boot.
2299 If this boot parameter is not specified, only the first
2300 security module asking for security registration will be
2301 loaded. An invalid security module name will be treated
2302 as if no module has been chosen.
2303
2304 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002305 Format: { "0" | "1" }
2306 See security/selinux/Kconfig help text.
2307 0 -- disable.
2308 1 -- enable.
2309 Default value is set via kernel config option.
2310 If enabled at boot time, /selinux/disable can be used
2311 later to disable prior to initial policy load.
2312
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002313 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002314
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315 shapers= [NET]
2316 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002317
Yinghai Lub05f78f2008-08-22 01:32:50 -07002318 show_msr= [x86] show boot-time MSR settings
2319 Format: { <integer> }
2320 Show boot-time (BIOS-initialized) MSR settings.
2321 The parameter means the number of CPUs to show,
2322 for example 1 means boot CPU only.
2323
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324 sim710= [SCSI,HW]
2325 See header of drivers/scsi/sim710.c.
2326
2327 simeth= [IA-64]
2328 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002329
Linus Torvalds1da177e2005-04-16 15:20:36 -07002330 slram= [HW,MTD]
2331
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002332 slub_debug[=options[,slabs]] [MM, SLUB]
2333 Enabling slub_debug allows one to determine the
2334 culprit if slab objects become corrupted. Enabling
2335 slub_debug can create guard zones around objects and
2336 may poison objects when not in use. Also tracks the
2337 last alloc / free. For more information see
2338 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002339
2340 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002341 Determines the maximum allowed order for slabs.
2342 A high setting may cause OOMs due to memory
2343 fragmentation. For more information see
2344 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002345
2346 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002347 The minimum number of objects per slab. SLUB will
2348 increase the slab order up to slub_max_order to
2349 generate a sufficiently large slab able to contain
2350 the number of objects indicated. The higher the number
2351 of objects the smaller the overhead of tracking slabs
2352 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002353 For more information see Documentation/vm/slub.txt.
2354
2355 slub_min_order= [MM, SLUB]
2356 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002357 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002358 For more information see Documentation/vm/slub.txt.
2359
2360 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002361 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002362 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002363 allocs to different slabs. Debug options disable
2364 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002365 For more information see Documentation/vm/slub.txt.
2366
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367 smart2= [HW]
2368 Format: <io1>[,<io2>[,...,<io8>]]
2369
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002370 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002371 attempt to substitute SMP alternatives once at boot.
2372
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002373 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2374 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2375 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2376 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2377 smsc-ircc2.ircc_irq= [HW] IRQ line
2378 smsc-ircc2.ircc_dma= [HW] DMA channel
2379 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2380 0: Toshiba Satellite 1800 (GP data pin select)
2381 1: Fast pin select (default)
2382 2: ATC IRMode
2383
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384 snd-ad1816a= [HW,ALSA]
2385
2386 snd-ad1848= [HW,ALSA]
2387
2388 snd-ali5451= [HW,ALSA]
2389
2390 snd-als100= [HW,ALSA]
2391
2392 snd-als4000= [HW,ALSA]
2393
2394 snd-azt2320= [HW,ALSA]
2395
2396 snd-cmi8330= [HW,ALSA]
2397
2398 snd-cmipci= [HW,ALSA]
2399
2400 snd-cs4231= [HW,ALSA]
2401
2402 snd-cs4232= [HW,ALSA]
2403
2404 snd-cs4236= [HW,ALSA]
2405
2406 snd-cs4281= [HW,ALSA]
2407
2408 snd-cs46xx= [HW,ALSA]
2409
2410 snd-dt019x= [HW,ALSA]
2411
2412 snd-dummy= [HW,ALSA]
2413
2414 snd-emu10k1= [HW,ALSA]
2415
2416 snd-ens1370= [HW,ALSA]
2417
2418 snd-ens1371= [HW,ALSA]
2419
2420 snd-es968= [HW,ALSA]
2421
2422 snd-es1688= [HW,ALSA]
2423
2424 snd-es18xx= [HW,ALSA]
2425
2426 snd-es1938= [HW,ALSA]
2427
2428 snd-es1968= [HW,ALSA]
2429
2430 snd-fm801= [HW,ALSA]
2431
2432 snd-gusclassic= [HW,ALSA]
2433
2434 snd-gusextreme= [HW,ALSA]
2435
2436 snd-gusmax= [HW,ALSA]
2437
2438 snd-hdsp= [HW,ALSA]
2439
2440 snd-ice1712= [HW,ALSA]
2441
2442 snd-intel8x0= [HW,ALSA]
2443
2444 snd-interwave= [HW,ALSA]
2445
2446 snd-interwave-stb=
2447 [HW,ALSA]
2448
2449 snd-korg1212= [HW,ALSA]
2450
2451 snd-maestro3= [HW,ALSA]
2452
2453 snd-mpu401= [HW,ALSA]
2454
2455 snd-mtpav= [HW,ALSA]
2456
2457 snd-nm256= [HW,ALSA]
2458
2459 snd-opl3sa2= [HW,ALSA]
2460
2461 snd-opti92x-ad1848=
2462 [HW,ALSA]
2463
2464 snd-opti92x-cs4231=
2465 [HW,ALSA]
2466
2467 snd-opti93x= [HW,ALSA]
2468
2469 snd-pmac= [HW,ALSA]
2470
2471 snd-rme32= [HW,ALSA]
2472
2473 snd-rme96= [HW,ALSA]
2474
2475 snd-rme9652= [HW,ALSA]
2476
2477 snd-sb8= [HW,ALSA]
2478
2479 snd-sb16= [HW,ALSA]
2480
2481 snd-sbawe= [HW,ALSA]
2482
2483 snd-serial= [HW,ALSA]
2484
2485 snd-sgalaxy= [HW,ALSA]
2486
2487 snd-sonicvibes= [HW,ALSA]
2488
2489 snd-sun-amd7930=
2490 [HW,ALSA]
2491
2492 snd-sun-cs4231= [HW,ALSA]
2493
2494 snd-trident= [HW,ALSA]
2495
2496 snd-usb-audio= [HW,ALSA,USB]
2497
2498 snd-via82xx= [HW,ALSA]
2499
2500 snd-virmidi= [HW,ALSA]
2501
2502 snd-wavefront= [HW,ALSA]
2503
2504 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002505
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002506 softlockup_panic=
2507 [KNL] Should the soft-lockup detector generate panics.
2508
Linus Torvalds1da177e2005-04-16 15:20:36 -07002509 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2510 See Documentation/sonypi.txt
2511
2512 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002513 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514
2515 spia_io_base= [HW,MTD]
2516 spia_fio_base=
2517 spia_pedr=
2518 spia_peddr=
2519
2520 sscape= [HW,OSS]
2521 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002522
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2524 See Documentation/scsi/st.txt.
2525
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002526 stacktrace [FTRACE]
2527 Enabled the stack tracer on boot up.
2528
Linus Torvalds1da177e2005-04-16 15:20:36 -07002529 sti= [PARISC,HW]
2530 Format: <num>
2531 Set the STI (builtin display/keyboard on the HP-PARISC
2532 machines) console (graphic card) which should be used
2533 as the initial boot-console.
2534 See also comment in drivers/video/console/sticore.c.
2535
2536 sti_font= [HW]
2537 See comment in drivers/video/console/sticore.c.
2538
2539 stifb= [HW]
2540 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2541
Trond Myklebustcbf11072009-08-09 15:06:19 -04002542 sunrpc.min_resvport=
2543 sunrpc.max_resvport=
2544 [NFS,SUNRPC]
2545 SunRPC servers often require that client requests
2546 originate from a privileged port (i.e. a port in the
2547 range 0 < portnr < 1024).
2548 An administrator who wishes to reserve some of these
2549 ports for other uses may adjust the range that the
2550 kernel's sunrpc client considers to be privileged
2551 using these two parameters to set the minimum and
2552 maximum port values.
2553
Greg Banks42a7fc42007-03-06 01:42:23 -08002554 sunrpc.pool_mode=
2555 [NFS]
2556 Control how the NFS server code allocates CPUs to
2557 service thread pools. Depending on how many NICs
2558 you have and where their interrupts are bound, this
2559 option will affect which CPUs will do NFS serving.
2560 Note: this parameter cannot be changed while the
2561 NFS server is running.
2562
2563 auto the server chooses an appropriate mode
2564 automatically using heuristics
2565 global a single global pool contains all CPUs
2566 percpu one pool for each CPU
2567 pernode one pool for each NUMA node (equivalent
2568 to global on non-NUMA machines)
2569
Trond Myklebustcbf11072009-08-09 15:06:19 -04002570 sunrpc.tcp_slot_table_entries=
2571 sunrpc.udp_slot_table_entries=
2572 [NFS,SUNRPC]
2573 Sets the upper limit on the number of simultaneous
2574 RPC calls that can be sent from the client to a
2575 server. Increasing these values may allow you to
2576 improve throughput, but will also increase the
2577 amount of memory reserved for use by the client.
2578
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002580
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 switches= [HW,M68k]
2582
2583 sym53c416= [HW,SCSI]
2584 See header of drivers/scsi/sym53c416.c.
2585
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002586 sysrq_always_enabled
2587 [KNL]
2588 Ignore sysrq setting - this boot parameter will
2589 neutralize any effect of /proc/sys/kernel/sysrq.
2590 Useful for debugging.
2591
Linus Torvalds1da177e2005-04-16 15:20:36 -07002592 t128= [HW,SCSI]
2593 See header of drivers/scsi/t128.c.
2594
2595 tdfx= [HW,DRM]
2596
David Brownell77437fd2008-07-23 21:28:33 -07002597 test_suspend= [SUSPEND]
2598 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2599 standby suspend) as the system sleep state to briefly
2600 enter during system startup. The system is woken from
2601 this state using a wakeup-capable RTC alarm.
2602
Linus Torvalds1da177e2005-04-16 15:20:36 -07002603 thash_entries= [KNL,NET]
2604 Set number of hash buckets for TCP connection
2605
Len Brownf8707ec2007-08-12 00:12:54 -04002606 thermal.act= [HW,ACPI]
2607 -1: disable all active trip points in all thermal zones
2608 <degrees C>: override all lowest active trip points
2609
Len Brownc52a7412007-08-14 15:49:32 -04002610 thermal.crt= [HW,ACPI]
2611 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002612 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002613
Len Brownf5487142007-08-12 00:12:44 -04002614 thermal.nocrt= [HW,ACPI]
2615 Set to disable actions on ACPI thermal zone
2616 critical and hot trip points.
2617
Len Brown72b33ef2007-08-12 00:12:17 -04002618 thermal.off= [HW,ACPI]
2619 1: disable ACPI thermal control
2620
Len Browna70cdc52007-08-12 00:12:35 -04002621 thermal.psv= [HW,ACPI]
2622 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002623 <degrees C>: override all passive trip points to this
2624 value
Len Browna70cdc52007-08-12 00:12:35 -04002625
Len Brown730ff342007-08-12 00:12:26 -04002626 thermal.tzp= [HW,ACPI]
2627 Specify global default ACPI thermal zone polling rate
2628 <deci-seconds>: poll all this frequency
2629 0: no polling (default)
2630
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631 tmscsim= [HW,SCSI]
2632 See comment before function dc390_setup() in
2633 drivers/scsi/tmscsim.c.
2634
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002635 topology= [S390]
2636 Format: {off | on}
2637 Specify if the kernel should make use of the cpu
2638 topology informations if the hardware supports these.
2639 The scheduler will make use of these informations and
2640 e.g. base its process migration decisions on it.
2641 Default is off.
2642
Linus Torvalds1da177e2005-04-16 15:20:36 -07002643 tp720= [HW,PS2]
2644
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002645 tpm_suspend_pcr=[HW,TPM]
2646 Format: integer pcr id
2647 Specify that at suspend time, the tpm driver
2648 should extend the specified pcr with zeros,
2649 as a workaround for some chips which fail to
2650 flush the last written pcr on TPM_SaveState.
2651 This will guarantee that all the other pcrs
2652 are saved.
2653
Li Zefan9d612be2009-06-24 17:33:15 +08002654 trace_buf_size=nn[KMG]
2655 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002656
Li Zefan020e5f82009-07-01 10:47:05 +08002657 trace_event=[event-list]
2658 [FTRACE] Set and start specified trace events in order
2659 to facilitate early boot debugging.
2660 See also Documentation/trace/events.txt
2661
Linus Torvalds1da177e2005-04-16 15:20:36 -07002662 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002663 Format:
2664 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2665
Alok Kataria395628e2008-10-24 17:22:01 -07002666 tsc= Disable clocksource-must-verify flag for TSC.
2667 Format: <string>
2668 [x86] reliable: mark tsc clocksource as reliable, this
2669 disables clocksource verification at runtime.
2670 Used to enable high-resolution timer mode on older
2671 hardware, and in virtualized environment.
2672
Randy Dunlapa9913042005-10-23 12:57:11 -07002673 turbografx.map[2|3]= [HW,JOY]
2674 TurboGraFX parallel port interface
2675 Format:
2676 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677 See also Documentation/input/joystick-parport.txt
2678
2679 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2680 See header of drivers/scsi/u14-34f.c.
2681
2682 uart401= [HW,OSS]
2683 Format: <io>,<irq>
2684
2685 uart6850= [HW,OSS]
2686 Format: <io>,<irq>
2687
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002688 uhash_entries= [KNL,NET]
2689 Set number of hash buckets for UDP/UDP-Lite connections
2690
Alan Stern5f8364b2006-12-05 16:29:55 -05002691 uhci-hcd.ignore_oc=
2692 [USB] Ignore overcurrent events (default N).
2693 Some badly-designed motherboards generate lots of
2694 bogus events, for ports that aren't wired to
2695 anything. Set this parameter to avoid log spamming.
2696 Note that genuine overcurrent events won't be
2697 reported either.
2698
Simon Arlotte3a61b02008-07-19 23:32:54 +01002699 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302700 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002701 Set unknown_nmi_panic=1 early on boot.
2702
Alan Sternb5e795f2007-02-20 15:00:53 -05002703 usbcore.autosuspend=
2704 [USB] The autosuspend time delay (in seconds) used
2705 for newly-detected USB devices (default 2). This
2706 is the time required before an idle device will be
2707 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002708 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002709
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002710 usbcore.usbfs_snoop=
2711 [USB] Set to log all usbfs traffic (default 0 = off).
2712
2713 usbcore.blinkenlights=
2714 [USB] Set to cycle leds on hubs (default 0 = off).
2715
2716 usbcore.old_scheme_first=
2717 [USB] Start with the old device initialization
2718 scheme (default 0 = off).
2719
2720 usbcore.use_both_schemes=
2721 [USB] Try the other device initialization scheme
2722 if the first one fails (default 1 = enabled).
2723
2724 usbcore.initial_descriptor_timeout=
2725 [USB] Specifies timeout for the initial 64-byte
2726 USB_REQ_GET_DESCRIPTOR request in milliseconds
2727 (default 5000 = 5.0 seconds).
2728
Linus Torvalds1da177e2005-04-16 15:20:36 -07002729 usbhid.mousepoll=
2730 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002731
Alan Sternd4f373e2008-11-10 14:07:45 -05002732 usb-storage.delay_use=
2733 [UMS] The delay in seconds before a new device is
2734 scanned for Logical Units (default 5).
2735
2736 usb-storage.quirks=
2737 [UMS] A list of quirks entries to supplement or
2738 override the built-in unusual_devs list. List
2739 entries are separated by commas. Each entry has
2740 the form VID:PID:Flags where VID and PID are Vendor
2741 and Product ID values (4-digit hex numbers) and
2742 Flags is a set of characters, each corresponding
2743 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002744 a = SANE_SENSE (collect more than 18 bytes
2745 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002746 b = BAD_SENSE (don't collect more than 18
2747 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002748 c = FIX_CAPACITY (decrease the reported
2749 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002750 h = CAPACITY_HEURISTICS (decrease the
2751 reported device capacity by one
2752 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002753 i = IGNORE_DEVICE (don't bind to this
2754 device);
2755 l = NOT_LOCKABLE (don't try to lock and
2756 unlock ejectable media);
2757 m = MAX_SECTORS_64 (don't transfer more
2758 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002759 o = CAPACITY_OK (accept the capacity
2760 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002761 r = IGNORE_RESIDUE (the device reports
2762 bogus residue values);
2763 s = SINGLE_LUN (the device has only one
2764 Logical Unit);
2765 w = NO_WP_DETECT (don't test whether the
2766 medium is write-protected).
2767 Example: quirks=0419:aaf5:rl,0421:0433:rc
2768
Ian Campbell14315592010-02-17 10:38:10 +00002769 userpte=
2770 [X86] Flags controlling user PTE allocations.
2771
2772 nohigh = do not allocate PTE pages in
2773 HIGHMEM regardless of setting
2774 of CONFIG_HIGHPTE.
2775
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302776 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002777 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002778 vdso=1: enable VDSO (default)
2779 vdso=0: disable VDSO mapping
2780
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302781 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002782 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2783 vdso32=1: enable 32-bit VDSO (default)
2784 vdso32=0: disable 32-bit VDSO mapping
2785
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002786 vector= [IA-64,SMP]
2787 vector=percpu: enable percpu vector domain
2788
Linus Torvalds1da177e2005-04-16 15:20:36 -07002789 video= [FB] Frame buffer configuration
2790 See Documentation/fb/modedb.txt.
2791
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002792 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002793 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002794 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002795 Use vga=ask for menu.
2796 This is actually a boot loader parameter; the value is
2797 passed to the kernel using a special protocol.
2798
Randy Dunlapa9913042005-10-23 12:57:11 -07002799 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800 size of <nn>. This can be used to increase the
2801 minimum size (128MB on x86). It can also be used to
2802 decrease the size and leave more room for directly
2803 mapped kernel RAM.
2804
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002805 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2806 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002807
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002808 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2809 Format: <command>
2810
2811 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2812 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002813
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002814 vt.cur_default= [VT] Default cursor shape.
2815 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2816 the parameters of the <Esc>[?A;B;Cc escape sequence;
2817 see VGA-softcursor.txt. Default: 2 = underline.
2818
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002819 vt.default_blu= [VT]
2820 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2821 Change the default blue palette of the console.
2822 This is a 16-member array composed of values
2823 ranging from 0-255.
2824
2825 vt.default_grn= [VT]
2826 Format: <green0>,<green1>,<green2>,...,<green15>
2827 Change the default green palette of the console.
2828 This is a 16-member array composed of values
2829 ranging from 0-255.
2830
2831 vt.default_red= [VT]
2832 Format: <red0>,<red1>,<red2>,...,<red15>
2833 Change the default red palette of the console.
2834 This is a 16-member array composed of values
2835 ranging from 0-255.
2836
2837 vt.default_utf8=
2838 [VT]
2839 Format=<0|1>
2840 Set system-wide default UTF-8 mode for all tty's.
2841 Default is 1, i.e. UTF-8 mode is enabled for all
2842 newly opened terminals.
2843
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002844 vt.global_cursor_default=
2845 [VT]
2846 Format=<-1|0|1>
2847 Set system-wide default for whether a cursor
2848 is shown on new VTs. Default is -1,
2849 i.e. cursors will be created by default unless
2850 overridden by individual drivers. 0 will hide
2851 cursors, 1 will display them.
2852
Linus Torvalds1da177e2005-04-16 15:20:36 -07002853 waveartist= [HW,OSS]
2854 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002855
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856 wd33c93= [HW,SCSI]
2857 See header of drivers/scsi/wd33c93.c.
2858
2859 wd7000= [HW,SCSI]
2860 See header of drivers/scsi/wd7000.c.
2861
Randy Dunlap4724ba52010-05-03 11:42:52 -07002862 watchdog timers [HW,WDT] For information on watchdog timers,
2863 see Documentation/watchdog/watchdog-parameters.txt
2864 or other driver-specific files in the
2865 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002866
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002867 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2868 default x2apic cluster mode on platforms
2869 supporting x2apic.
2870
Jacob Panbb24c472009-09-02 07:37:17 -07002871 x86_mrst_timer= [X86-32,APBT]
2872 Choose timer option for x86 Moorestown MID platform.
2873 Two valid options are apbt timer only and lapic timer
2874 plus one apbt timer for broadcast timer.
2875 x86_mrst_timer=apbt_only | lapic_and_apbt
2876
Linus Torvalds1da177e2005-04-16 15:20:36 -07002877 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2878 xd_geo= See header of drivers/block/xd.c.
2879
2880 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002881 Format:
2882 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002883
Randy Dunlapa9913042005-10-23 12:57:11 -07002884______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002885
2886TODO:
2887
2888 Add documentation for ALSA options.
2889 Add more DRM drivers.