blob: 839b21b0699ac10a1991c47455cddd05ced6491b [file] [log] [blame]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020061 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070062 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070071 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070072 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070075 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070078 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070082 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070093 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090096 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070099 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500101 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500103 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700111 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700114 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500126need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Karsten Weiss55588702007-02-13 13:26:21 +0100128There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700129See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
jens m. noedler9c4751f2006-09-29 02:00:27 -0700137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530144 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800145 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800146 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700151 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800153 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Randy Dunlap53471122008-03-12 18:10:51 -0400155 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Len Browna1fdcc02007-03-11 03:26:14 -0400157 acpi_apic_instance= [ACPI, IOAPIC]
158 Format: <int>
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400161 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400162
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
165 acpi_backlight=video
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
169
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200193
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800197
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
201 See above.
202
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
205 default in APIC mode
206
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
209 default in PIC mode
210
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
213
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 use by PCI
216 Format: <irq>,<irq>...
217
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
222
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
227
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530228 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
Randy Dunlap4af94f32009-04-17 18:30:28 -0700233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
235
236 acpi_serialize [HW,ACPI] force serialization of AML methods
237
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
241
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800244 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700245 See Documentation/power/video.txt for information on
246 s3_bios and s3_mode.
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800257 sci_force_enable causes the kernel to set SCI_EN directly
258 on resume from S1/S3 (which is against the ACPI spec,
259 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700260
261 acpi_use_timer_override [HW,ACPI]
262 Use timer override. For some broken Nvidia NF5 boards
263 that require a timer override, but don't have HPET
264
Luca Tettamanti7e905602009-03-30 00:01:27 +0200265 acpi_enforce_resources= [ACPI]
266 { strict | lax | no }
267 Check for resource conflicts between native drivers
268 and ACPI OperationRegions (SystemIO and SystemMemory
269 only). IO ports and memory declared in ACPI might be
270 used by the ACPI subsystem in arbitrary AML code and
271 can interfere with legacy drivers.
272 strict (default): access to resources claimed by ACPI
273 is denied; legacy drivers trying to access reserved
274 resources will fail to bind to device using them.
275 lax: access to resources claimed by ACPI is allowed;
276 legacy drivers trying to access reserved resources
277 will bind successfully but a warning message is logged.
278 no: ACPI OperationRegions are not marked as reserved,
279 no further checks are performed.
280
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 ad1848= [HW,OSS]
282 Format: <io>,<irq>,<dma>,<dma2>,<type>
283
Randy Dunlap4af94f32009-04-17 18:30:28 -0700284 add_efi_memmap [EFI; X86] Include EFI memory map in
285 kernel's map of available physical RAM.
286
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 advansys= [HW,SCSI]
288 See header of drivers/scsi/advansys.c.
289
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
292
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700296
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700297 agp= [AGP]
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 aha152x= [HW,SCSI]
304 See Documentation/scsi/aha152x.txt.
305
306 aha1542= [HW,SCSI]
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
308
309 aic7xxx= [HW,SCSI]
310 See Documentation/scsi/aic7xxx.txt.
311
312 aic79xx= [HW,SCSI]
313 See Documentation/scsi/aic79xx.txt.
314
Russell Kingd944d542010-02-20 16:13:29 +0000315 alignment= [KNL,ARM]
316 Allow the default userspace alignment fault handler
317 behaviour to be specified. Bit 0 enables warnings,
318 bit 1 enables fixups, and bit 2 sends a segfault.
319
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200320 amd_iommu= [HW,X86-84]
321 Pass parameters to the AMD IOMMU driver in the system.
322 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900323 fullflush - enable flushing of IO/TLB entries when
324 they are unmapped. Otherwise they are
325 flushed before they will be reused, which
326 is a lot of faster
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 amijoy.map= [HW,JOY] Amiga joystick support
329 Map of devices attached to JOY0DAT and JOY1DAT
330 Format: <a>,<b>
331 See also Documentation/kernel/input/joystick.txt
332
333 analog.map= [HW,JOY] Analog joystick and gamepad support
334 Specifies type or capabilities of an analog joystick
335 connected to one of 16 gameports
336 Format: <type1>,<type2>,..<type16>
337
Randy Dunlapa9913042005-10-23 12:57:11 -0700338 apc= [HW,SPARC]
339 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 Format: noidle
341 Disable APC CPU standby support. SPARCstation-Fox does
342 not play well with APC CPU idle - disable it if you have
343 APC and your system crashes randomly.
344
Randy Dunlapca1eda22009-05-06 16:02:58 -0700345 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700346 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 Format: { quiet (default) | verbose | debug }
348 Change the amount of debugging information output
349 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700350
Brian Haleyb0f83b22010-02-04 13:36:50 -0800351 autoconf= [IPV6]
352 See Documentation/networking/ipv6.txt.
353
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400354 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
355 Limit apic dumping. The parameter defines the maximal
356 number of local apics being dumped. Also it is possible
357 to set it to "all" by meaning -- no limit here.
358 Format: { 1 (default) | 2 | ... | all }.
359 The parameter valid if only apic=debug or
360 apic=verbose is specified.
361 Example: apic=debug show_lapic=all
362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700364 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
367 Format: <io>,<irq>,<nodeID>
368
369 ataflop= [HW,M68k]
370
371 atarimouse= [HW,MOUSE] Atari Mouse
372
373 atascsi= [HW,SCSI] Atari SCSI
374
375 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
376 EzKey and similar keyboards
377
378 atkbd.reset= [HW] Reset keyboard during initialization
379
Randy Dunlapa9913042005-10-23 12:57:11 -0700380 atkbd.set= [HW] Select keyboard code set
381 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
384 keyboards
385
386 atkbd.softraw= [HW] Choose between synthetic and real raw mode
387 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700388
389 atkbd.softrepeat= [HW]
390 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391
392 autotest [IA64]
393
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 baycom_epp= [HW,AX25]
395 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700396
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
398 Format: <io>,<mode>
399 See header of drivers/net/hamradio/baycom_par.c.
400
Randy Dunlapa9913042005-10-23 12:57:11 -0700401 baycom_ser_fdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 Format: <io>,<irq>,<mode>[,<baud>]
404 See header of drivers/net/hamradio/baycom_ser_fdx.c.
405
Randy Dunlapa9913042005-10-23 12:57:11 -0700406 baycom_ser_hdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 Format: <io>,<irq>,<mode>
409 See header of drivers/net/hamradio/baycom_ser_hdx.c.
410
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700411 boot_delay= Milliseconds to delay each printk during boot.
412 Values larger than 10 seconds (10000) are changed to
413 no delay (0).
414 Format: integer
415
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700416 bootmem_debug [KNL] Enable bootmem allocator debug messages.
417
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700419 bttv.radio= Most important insmod options are available as
420 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
422 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
423
424 BusLogic= [HW,SCSI]
425 See drivers/scsi/BusLogic.c, comment before function
426 BusLogic_ParseDriverOptions().
427
428 c101= [NET] Moxa C101 synchronous serial card
429
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700430 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 Sometimes CPU hardware bugs make them report the cache
432 size incorrectly. The kernel will attempt work arounds
433 to fix known problems, but for some CPUs it is not
434 possible to determine what the correct size should be.
435 This option provides an override for these situations.
436
James Morris20510f22007-10-16 23:31:32 -0700437 capability.disable=
438 [SECURITY] Disable capabilities. This would normally
439 be used only if an alternative security model is to be
440 configured. Potentially dangerous and should only be
441 used if you are entirely sure of the consequences.
442
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100443 ccw_timeout_log [S390]
444 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445
Paul Menage8bab8dd2008-04-04 14:29:57 -0700446 cgroup_disable= [KNL] Disable a particular controller
447 Format: {name of the controller(s) to disable}
448 {Currently supported controllers - "memory"}
449
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 checkreqprot [SELINUX] Set initial checkreqprot flag value.
451 Format: { "0" | "1" }
452 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700453 0 -- check protection applied by kernel (includes
454 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 1 -- check protection requested by application.
456 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700457 Value can be changed at runtime via
458 /selinux/checkreqprot.
459
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100460 cio_ignore= [S390]
461 See Documentation/s390/CommonIO for details.
462
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700463 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700464 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200465 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700466 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200467 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 Format: { pit | tsc | cyclone | pmtmr }
469
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700470 clocksource= [GENERIC_TIME] Override the default clocksource
471 Format: <string>
472 Override the default clocksource and use the clocksource
473 with the name specified.
474 Some clocksource names to choose from, depending on
475 the platform:
476 [all] jiffies (this is the base, fallback clocksource)
477 [ACPI] acpi_pm
478 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
479 pxa_timer,timer3,32k_counter,timer0_1
480 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700481 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700482 scx200_hrt on Geode; cyclone on IBM x440
483 [MIPS] MIPS
484 [PARISC] cr16
485 [S390] tod
486 [SH] SuperH
487 [SPARC64] tick
488 [X86-64] hpet,tsc
489
Andi Kleenac72e782008-01-30 13:33:21 +0100490 clearcpuid=BITNUM [X86]
491 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800492 arch/x86/include/asm/cpufeature.h for the valid bit
493 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100494 stable over kernel options, but the vendor specific
495 ones should be.
496 Also note that user programs calling CPUID directly
497 or using the feature without checking anything
498 will still see it. This just prevents it from
499 being used by the kernel or shown in /proc/cpuinfo.
500 Also note the kernel might malfunction if you disable
501 some critical bits.
502
Robert Jennings14f966e2009-04-15 05:55:32 +0000503 cmo_free_hint= [PPC] Format: { yes | no }
504 Specify whether pages are marked as being inactive
505 when they are freed. This is used in CMO environments
506 to determine OS memory pressure for page stealing by
507 a hypervisor.
508 Default: yes
509
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530510 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100511 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100512 Range: 0 - 8192
513 Default: 64
514
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700516 Format:
517 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518
519 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
520 Format: <io>[,<irq>]
521
Randy Dunlapa9913042005-10-23 12:57:11 -0700522 com90xx= [HW,NET]
523 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 Format: <io>[,<irq>[,<memstart>]]
525
526 condev= [HW,S390] console device
527 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 console= [KNL] Output console device and options.
530
531 tty<n> Use the virtual console device <n>.
532
533 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800534 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800536 the form "bbbbpnf", where "bbbb" is the baud rate,
537 "p" is parity ("n", "o", or "e"), "n" is number of
538 bits, and "f" is flow control ("r" for RTS or
539 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800541 See Documentation/serial-console.txt for more
542 information. See
543 Documentation/networking/netconsole.txt for an
544 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700546 uart[8250],io,<addr>[,options]
547 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 Start an early, polled-mode console on the 8250/16550
549 UART at the specified I/O port or MMIO address,
550 switching to the matching ttyS device later. The
551 options are the same as for ttyS, above.
552
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700553 If the device connected to the port is not a TTY but a braille
554 device, prepend "brl," before the device type, for instance
555 console=brl,ttyS0
556 For now, only VisioBraille is supported.
557
Daniel Mackf324edc2009-06-16 15:33:52 -0700558 consoleblank= [KNL] The console blank (screen saver) timeout in
559 seconds. Defaults to 10*60 = 10mins. A value of 0
560 disables the blank timer.
561
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800562 coredump_filter=
563 [KNL] Change the default value for
564 /proc/<pid>/coredump_filter.
565 See also Documentation/filesystems/proc.txt.
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700568 Format:
569 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700571 crashkernel=nn[KMG]@ss[KMG]
572 [KNL] Reserve a chunk of physical memory to
573 hold a kernel to switch to with kexec on panic.
574
Bernhard Wallefb391592007-10-18 23:41:02 -0700575 crashkernel=range1:size1[,range2:size2,...][@offset]
576 [KNL] Same as above, but depends on the memory
577 in the running system. The syntax of range is
578 start-[end] where start and end are both
579 a memory unit (amount[KMG]). See also
580 Documentation/kdump/kdump.txt for a example.
581
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 cs89x0_dma= [HW,NET]
583 Format: <dma>
584
585 cs89x0_media= [HW,NET]
586 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700587
Randy Dunlapa9913042005-10-23 12:57:11 -0700588 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 See header of drivers/s390/block/dasd_devmap.c.
590
591 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
592 (one device per port)
593 Format: <port#>,<type>
594 See also Documentation/input/joystick-parport.txt
595
596 debug [KNL] Enable kernel debugging (events log level).
597
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700598 debug_locks_verbose=
599 [KNL] verbose self-tests
600 Format=<0|1>
601 Print debugging info while doing the locking API
602 self-tests.
603 We default to 0 (no extra messages), setting it to
604 1 will print _a lot_ more information - normally
605 only useful to kernel developers.
606
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700607 debug_objects [KNL] Enable object debugging
608
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500609 no_debug_objects
610 [KNL] Disable object debugging
611
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200612 debugpat [X86] Enable PAT debugging
613
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200614 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 Format: <area>[,<node>]
616 See also Documentation/networking/decnet.txt.
617
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700618 default_hugepagesz=
619 [same as hugepagesz=] The size of the default
620 HugeTLB page size. This is the size represented by
621 the legacy /proc/ hugepages APIs, used for SHM, and
622 default size when mounting hugetlbfs filesystems.
623 Defaults to the default architecture's huge page size
624 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700625
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 dhash_entries= [KNL]
627 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 digi= [HW,SERIAL]
630 IO parameters + enable/disable command.
631
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000634 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635
Brian Haleyb0f83b22010-02-04 13:36:50 -0800636 disable= [IPV6]
637 See Documentation/networking/ipv6.txt.
638
639 disable_ipv6= [IPV6]
640 See Documentation/networking/ipv6.txt.
641
Yinghai Lu95ffa242008-04-29 03:52:33 -0700642 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700643 The kernel tries to adjust MTRR layout from continuous
644 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700645 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700646
Yinghai Lu093af8d2008-01-30 13:33:32 +0100647 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530653 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 Disable PIN 1 of APIC timer
655 Can be useful to work around chipset bugs.
656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 dmasound= [HW,OSS] Sound subsystem buffers
658
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700659 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
660 this option disables the debugging code at boot.
661
662 dma_debug_entries=<number>
663 This option allows to tune the number of preallocated
664 entries for DMA-API debugging code. One entry is
665 required per DMA-API allocation. Use this if the
666 DMA-API debugging code disables itself because the
667 architectural default is too low.
668
Joerg Roedel1745de52009-05-22 21:49:51 +0200669 dma_debug_driver=<driver_name>
670 With this option the DMA-API debugging driver
671 filter feature can be enabled at boot time. Just
672 pass the driver to filter for as the parameter.
673 The filter can be disabled or changed to another
674 driver later using sysfs.
675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 dscc4.setup= [NET]
677
678 dtc3181e= [HW,SCSI]
679
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700680 dynamic_printk Enables pr_debug()/dev_dbg() calls if
681 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
682 These can also be switched on/off via
683 <debugfs>/dynamic_printk/modules
684
685 earlycon= [KNL] Output early console device and options.
686 uart[8250],io,<addr>[,options]
687 uart[8250],mmio,<addr>[,options]
688 Start an early, polled-mode console on the 8250/16550
689 UART at the specified I/O port or MMIO address.
690 The options are the same as for ttyS, above.
691
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530692 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 earlyprintk=vga
694 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500695 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500696 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697
Randy Dunlapa9913042005-10-23 12:57:11 -0700698 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 takes over.
700
Yinghai Lu5c059172008-07-24 17:29:40 -0700701 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
703 Currently only ttyS0 and ttyS1 are supported.
704
705 Interaction with the standard serial driver is not
706 very good.
707
708 The VGA output is eventually overwritten by the real
709 console.
710
711 eata= [HW,SCSI]
712
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700714 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 eisa_irq_edge= [PARISC,HW]
717 See header of drivers/parisc/eisa.c.
718
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700719 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700721 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
723 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800724 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700725 See Documentation/block/as-iosched.txt and
726 Documentation/block/deadline-iosched.txt for details.
727
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530728 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700729 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800730 image elf header. Generally kexec loader will
731 pass this option to capture kernel.
732 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700734 enable_mtrr_cleanup [X86]
735 The kernel tries to adjust MTRR layout from continuous
736 to discrete, to make X server driver able to add WB
737 entry later. This parameter enables that.
738
Randy Dunlapca1eda22009-05-06 16:02:58 -0700739 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700740 Enable PIN 1 of APIC timer
741 Can be useful to work around chipset bugs
742 (in particular on some ATI chipsets).
743 The kernel tries to set a reasonable default.
744
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 enforcing [SELINUX] Set initial enforcing status.
746 Format: {"0" | "1"}
747 See security/selinux/Kconfig help text.
748 0 -- permissive (log only, no denials).
749 1 -- enforcing (deny and log).
750 Default value is 0.
751 Value can be changed at runtime via /selinux/enforce.
752
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 ether= [HW,NET] Ethernet cards parameters
754 This option is obsoleted by the "netdev=" option, which
755 has equivalent usage. See its documentation for details.
756
757 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
758 Format: <io>[,<irq>]
759
Akinobu Mitade1ba092006-12-08 02:39:42 -0800760 failslab=
761 fail_page_alloc=
762 fail_make_request=[KNL]
763 General fault injection mechanism.
764 Format: <interval>,<probability>,<space>,<times>
765 See also /Documentation/fault-injection/.
766
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 fd_mcs= [HW,SCSI]
768 See header of drivers/scsi/fd_mcs.c.
769
770 fdomain= [HW,SCSI]
771 See header of drivers/scsi/fdomain.c.
772
773 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000774 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775
Alex Chiangf13ae302008-05-08 14:03:23 -0600776 force_pal_cache_flush
777 [IA-64] Avoid check_sal_cache_flush which may hang on
778 buggy SAL_CACHE_FLUSH implementations. Using this
779 parameter will force ia64_sal_cache_flush to call
780 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
781
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100782 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400783 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100784 as early as possible in order to facilitate early
785 boot debugging.
786
787 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400788 [FTRACE] will dump the trace buffers on oops.
789
790 ftrace_filter=[function-list]
791 [FTRACE] Limit the functions traced by the function
792 tracer at boot up. function-list is a comma separated
793 list of functions. This list can be changed at run
794 time by the set_ftrace_filter file in the debugfs
795 tracing directory.
796
797 ftrace_notrace=[function-list]
798 [FTRACE] Do not trace the functions specified in
799 function-list. This list can be changed at run time
800 by the set_ftrace_notrace file in the debugfs
801 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100802
Stefan Assmann369bc182009-10-12 22:17:21 +0200803 ftrace_graph_filter=[function-list]
804 [FTRACE] Limit the top level callers functions traced
805 by the function graph tracer at boot up.
806 function-list is a comma separated list of functions
807 that can be changed at run time by the
808 set_graph_function file in the debugfs tracing directory.
809
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 gamecon.map[2|3]=
811 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
812 support via parallel port (up to 5 devices per port)
813 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
814 See also Documentation/input/joystick-parport.txt
815
816 gamma= [HW,DRM]
817
Yinghai Luaaf23042008-01-30 13:33:09 +0100818 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
819 Format: off | on
820 default: on
821
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700822 gcov_persist= [GCOV] When non-zero (default), profiling data for
823 kernel modules is saved and remains accessible via
824 debugfs, even when the module is unloaded/reloaded.
825 When zero, profiling data is discarded and associated
826 debugfs files are removed at module unload time.
827
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 gdth= [HW,SCSI]
829 See header of drivers/scsi/gdth.c.
830
831 gpt [EFI] Forces disk with valid GPT signature but
832 invalid Protective MBR to be treated as GPT.
833
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 gvp11= [HW,SCSI]
835
836 hashdist= [KNL,NUMA] Large hashes allocated during boot
837 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700838 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700839 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840
841 hcl= [IA-64] SGI's Hardware Graph compatibility layer
842
843 hd= [EIDE] (E)IDE hard drive subsystem geometry
844 Format: <cyl>,<head>,<sect>
845
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
847 size of <nn>. This works even on boxes that have no
848 highmem otherwise. This also works to reduce highmem
849 size on bigger boxes.
850
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800851 highres= [KNL] Enable/disable high resolution timer mode.
852 Valid parameters: "on", "off"
853 Default: "on"
854
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 hisax= [HW,ISDN]
856 See Documentation/isdn/README.HiSax.
857
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700858 hlt [BUGS=ARM,SH]
859
860 hpet= [X86-32,HPET] option to control HPET usage
861 Format: { enable (default) | disable | force |
862 verbose }
863 disable: disable HPET and use PIT instead
864 force: allow force enabled of undocumented chips (ICH4,
865 VIA, nVidia)
866 verbose: show contents of HPET registers during setup
867
Andi Kleenb4718e62008-07-23 21:27:51 -0700868 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
869 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700870 On x86-64 and powerpc, this option can be specified
871 multiple times interleaved with hugepages= to reserve
872 huge pages of different sizes. Valid pages sizes on
873 x86-64 are 2M (when the CPU supports "pse") and 1G
874 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700875 Note that 1GB pages can only be allocated at boot time
876 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900877
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100878 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
879 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100880 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
881 If specified, z/VM IUCV HVC accepts connections
882 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100883
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700884 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700885 or register an additional I2C bus that is not
886 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700887 Format:
888 <bus_id>,<clkrate>
889
Jiri Kosina36d95732008-10-06 02:51:09 -0400890 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200892 i8042.dumbkbd [HW] Pretend that controller can only read data from
893 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 (Don't attempt to blink the leds)
895 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500896 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400897 i8042.noloop [HW] Disable the AUX Loopback command while probing
898 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 i8042.nomux [HW] Don't check presence of an active multiplexing
900 controller
901 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
902 controllers
903 i8042.panicblink=
904 [HW] Frequency with which keyboard LEDs should blink
905 when kernel panics (default is 0.5 sec)
906 i8042.reset [HW] Reset the controller during init and cleanup
907 i8042.unlock [HW] Unlock (ignore) the keylock
908
909 i810= [HW,DRM]
910
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700911 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
912 indicates that the driver is running on unsupported
913 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
915 does not match list of supported models.
916 i8k.power_status
917 [HW] Report power status in /proc/i8k
918 (disabled by default)
919 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
920 capability is set.
921
922 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
923 See Documentation/mca.txt.
924
925 icn= [HW,ISDN]
926 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
927
David Fries0af80c02009-02-25 20:28:21 +0100928 ide-core.nodma= [HW] (E)IDE subsystem
929 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200930 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
931 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100932 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700934 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
935 Claim all unknown PCI IDE storage controllers.
936
Andi Kleenf039b752007-05-02 19:27:12 +0200937 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800938 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
939 Poll forces a polling idle loop that can slightly
940 improve the performance of waking up a idle CPU, but
941 will use a lot of power and make the system run hot.
942 Not recommended.
943 idle=mwait: On systems which support MONITOR/MWAIT but
944 the kernel chose to not use it because it doesn't save
945 as much power as a normal idle loop, use the
946 MONITOR/MWAIT idle loop anyways. Performance should be
947 the same as idle=poll.
948 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800949 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800950 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700951
Ingo Molnar792908222006-12-06 20:40:51 -0800952 ignore_loglevel [KNL]
953 Ignore loglevel setting - this will print /all/
954 kernel messages to the console. Useful for debugging.
955
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 ihash_entries= [KNL]
957 Set number of hash buckets for inode cache.
958
Mimi Zohar3323eec2009-02-04 09:06:58 -0500959 ima_audit= [IMA]
960 Format: { "0" | "1" }
961 0 -- integrity auditing messages. (Default)
962 1 -- enable informational integrity auditing messages.
963
964 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700965 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500966 default: "sha1"
967
Eric Paris5789ba32009-05-21 15:47:06 -0400968 ima_tcb [IMA]
969 Load a policy which meets the needs of the Trusted
970 Computing Base. This means IMA will measure all
971 programs exec'd, files mmap'd for exec, and all files
972 opened for read by uid=0.
973
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 in2000= [HW,SCSI]
975 See header of drivers/scsi/in2000.c.
976
977 init= [KNL]
978 Format: <full_path>
979 Run specified binary instead of /sbin/init as init
980 process.
981
982 initcall_debug [KNL] Trace initcalls as they are executed. Useful
983 for working out where the kernel is dying during
984 startup.
985
986 initrd= [BOOT] Specify the location of the initial ramdisk
987
988 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
989 Format: <irq>
990
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700991 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800992 on
993 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700994 off
995 Disable intel iommu driver.
996 igfx_off [Default Off]
997 By default, gfx is mapped as normal device. If a gfx
998 device has a dedicated DMAR unit, the DMAR unit is
999 bypassed by not enabling DMAR with this option. In
1000 this case, gfx device will use physical address for
1001 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001002 forcedac [x86_64]
1003 With this option iommu will not optimize to look
1004 for io virtual address below 32 bit forcing dual
1005 address cycle on pci bus for cards supporting greater
1006 than 32 bit addressing. The default is to look
1007 for translation below 32 bit and if not available
1008 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001009 strict [Default Off]
1010 With this option on every unmap_single operation will
1011 result in a hardware IOTLB flush operation as opposed
1012 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001013
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001014 inttest= [IA64]
1015
1016 iomem= Disable strict checking of access to MMIO memory
1017 strict regions from userspace.
1018 relaxed
1019
1020 iommu= [x86]
1021 off
1022 force
1023 noforce
1024 biomerge
1025 panic
1026 nopanic
1027 merge
1028 nomerge
1029 forcesac
1030 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001031 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001032
1033 io7= [HW] IO7 for Marvel based alpha systems
1034 See comment before marvel_specify_io7 in
1035 arch/alpha/kernel/core_marvel.c.
1036
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301037 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001038 0x80
1039 Standard port 0x80 based delay
1040 0xed
1041 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001042 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001043 Simple two microseconds delay
1044 none
1045 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001046
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001048 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049
1050 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001051 See comment before ip2_setup() in
1052 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053
1054 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1055 See header of drivers/scsi/ips.c.
1056
Alan Cox200803d2005-06-28 20:45:18 -07001057 irqfixup [HW]
1058 When an interrupt is not handled search all handlers
1059 for it. Intended to get systems with badly broken
1060 firmware running.
1061
1062 irqpoll [HW]
1063 When an interrupt is not handled search all handlers
1064 for it. Also check all handlers each timer
1065 interrupt. Intended to get systems with badly broken
1066 firmware running.
1067
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001069 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070
1071 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001072 Format:
1073 <cpu number>,...,<cpu number>
1074 or
Li Zefanb225d442008-11-06 12:53:39 -08001075 <cpu number>-<cpu number>
1076 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001077 or a mixture
1078 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001079
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 This option can be used to specify one or more CPUs
1081 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001082 algorithms. You can move a process onto or off an
1083 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 <cpu number> begins at 0 and the maximum value is
1085 "number of CPUs in system - 1".
1086
1087 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001088 alternative -- manually setting the CPU mask of all
1089 tasks in the system -- can cause problems and
1090 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091
Randy Dunlapa9913042005-10-23 12:57:11 -07001092 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093
1094 js= [HW,JOY] Analog joystick
1095 See Documentation/input/joystick.txt.
1096
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001097 keepinitrd [HW,ARM]
1098
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301099 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001100 specifies the amount of memory usable by the kernel
1101 for non-movable allocations. The requested amount is
1102 spread evenly throughout all nodes in the system. The
1103 remaining memory in each node is used for Movable
1104 pages. In the event, a node is too small to have both
1105 kernelcore and Movable pages, kernelcore pages will
1106 take priority and other nodes will have a larger number
1107 of kernelcore pages. The Movable zone is used for the
1108 allocation of pages that may be reclaimed or moved
1109 by the page migration subsystem. This means that
1110 HugeTLB pages may not be allocated from this zone.
1111 Note that allocations like PTEs-from-HighMem still
1112 use the HighMem zone if it exists, and the Normal
1113 zone if it does not.
1114
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001115 kgdboc= [HW] kgdb over consoles.
1116 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001117 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001118 Format: <serial_device>[,baud]
1119
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001120 kmac= [MIPS] korina ethernet MAC address.
1121 Configure the RouterBoard 532 series on-chip
1122 Ethernet adapter MAC address.
1123
Catalin Marinas04f70332009-06-11 13:22:39 +01001124 kmemleak= [KNL] Boot-time kmemleak enable/disable
1125 Valid arguments: on, off
1126 Default: on
1127
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301128 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001129 in oops dumps.
1130
Andre Przywarafef07aa2009-07-10 14:20:35 +02001131 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1132 Default is 0 (don't ignore, but inject #GP)
1133
1134 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1135 Default is 1 (enabled)
1136
1137 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1138 Default is 0 (off)
1139
1140 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1141 for all guests.
1142 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1143
1144 kvm-intel.bypass_guest_pf=
1145 [KVM,Intel] Disables bypassing of guest page faults
1146 on Intel chips. Default is 1 (enabled)
1147
1148 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1149 (virtualized MMU) support on capable Intel chips.
1150 Default is 1 (enabled)
1151
1152 kvm-intel.emulate_invalid_guest_state=
1153 [KVM,Intel] Enable emulation of invalid guest states
1154 Default is 0 (disabled)
1155
1156 kvm-intel.flexpriority=
1157 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1158 Default is 1 (enabled)
1159
1160 kvm-intel.unrestricted_guest=
1161 [KVM,Intel] Disable unrestricted guest feature
1162 (virtualized real and unpaged mode) on capable
1163 Intel chips. Default is 1 (enabled)
1164
1165 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1166 feature (tagged TLBs) on capable Intel chips.
1167 Default is 1 (enabled)
1168
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 l2cr= [PPC]
1170
Robert Brosea78bfbf2008-03-29 07:20:23 +11001171 l3cr= [PPC]
1172
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001173 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001174 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301176 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001177 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001178
FD Camifcb71f62008-01-06 19:08:56 +01001179 libata.dma= [LIBATA] DMA control
1180 libata.dma=0 Disable all PATA and SATA DMA
1181 libata.dma=1 PATA and SATA Disk DMA only
1182 libata.dma=2 ATAPI (CDROM) DMA only
1183 libata.dma=4 Compact Flash DMA only
1184 Combinations also work, so libata.dma=3 enables DMA
1185 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001186
1187 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1188 libata.ignore_hpa=0 keep BIOS limits (default)
1189 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001190
Dave Jones78e70c22007-09-27 11:50:13 -04001191 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1192 when set.
1193 Format: <int>
1194
Tejun Heo33267322008-02-13 09:15:09 +09001195 libata.force= [LIBATA] Force configurations. The format is comma
1196 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001197 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001198 matching port, link or device. Basically, it matches
1199 the ATA ID string printed on console by libata. If
1200 the whole ID part is omitted, the last PORT and DEVICE
1201 values are used. If ID hasn't been specified yet, the
1202 configuration applies to all ports, links and devices.
1203
1204 If only DEVICE is omitted, the parameter applies to
1205 the port and all links and devices behind it. DEVICE
1206 number of 0 either selects the first device or the
1207 first fan-out link behind PMP device. It does not
1208 select the host link. DEVICE number of 15 selects the
1209 host link and device attached to it.
1210
1211 The VAL specifies the configuration to force. As long
1212 as there's no ambiguity shortcut notation is allowed.
1213 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1214 The following configurations can be forced.
1215
1216 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1217 Any ID with matching PORT is used.
1218
1219 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1220
1221 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1222 udma[/][16,25,33,44,66,100,133] notation is also
1223 allowed.
1224
1225 * [no]ncq: Turn on or off NCQ.
1226
Tejun Heo05944bd2008-08-13 20:19:09 +09001227 * nohrst, nosrst, norst: suppress hard, soft
1228 and both resets.
1229
Tejun Heo33267322008-02-13 09:15:09 +09001230 If there are multiple matching configurations changing
1231 the same attribute, the last one is used.
1232
Randy Dunlap7c4be252009-01-06 14:42:44 -08001233 lmb=debug [KNL] Enable lmb debug messages.
1234
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001236 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001238 lockd.nlm_grace_period=P [NFS] Assign grace period.
1239 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001241 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1242 Format: <integer>
1243
1244 lockd.nlm_timeout=T [NFS] Assign timeout value.
1245 Format: <integer>
1246
1247 lockd.nlm_udpport=M [NFS] Assign UDP port.
1248 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
1250 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1251 Format: <irq>
1252
1253 loglevel= All Kernel Messages with a loglevel smaller than the
1254 console loglevel will be printed to the console. It can
1255 also be changed with klogd or other programs. The
1256 loglevels are defined as follows:
1257
1258 0 (KERN_EMERG) system is unusable
1259 1 (KERN_ALERT) action must be taken immediately
1260 2 (KERN_CRIT) critical conditions
1261 3 (KERN_ERR) error conditions
1262 4 (KERN_WARNING) warning conditions
1263 5 (KERN_NOTICE) normal but significant condition
1264 6 (KERN_INFO) informational
1265 7 (KERN_DEBUG) debug-level messages
1266
1267 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001268 Format: { n | nk | nM }
1269 n must be a power of two. The default size
1270 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271
Randy Dunlapaccaa242007-10-16 01:29:37 -07001272 logo.nologo [FB] Disables display of the built-in Linux logo.
1273 This may be used to provide more screen space for
1274 kernel log messages and is useful when debugging
1275 kernel boot problems.
1276
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277 lp=0 [LP] Specify parallel ports to use, e.g,
1278 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1279 lp=reset first parallel port). 'lp=0' disables the
1280 lp=auto printer driver. 'lp=reset' (which can be
1281 specified in addition to the ports) causes
1282 attached printers to be reset. Using
1283 lp=port1,port2,... specifies the parallel ports
1284 to associate lp devices with, starting with
1285 lp0. A port specification may be 'none' to skip
1286 that lp device, or a parport name such as
1287 'parport0'. Specifying 'lp=auto' instead of a
1288 port specification list means that device IDs
1289 from each port should be examined, to see if
1290 an IEEE 1284-compliant printer is attached; if
1291 so, the driver will manage that printer.
1292 See also header of drivers/char/lp.c.
1293
1294 lpj=n [KNL]
1295 Sets loops_per_jiffy to given constant, thus avoiding
1296 time-consuming boot-time autodetection (up to 250 ms per
1297 CPU). 0 enables autodetection (default). To determine
1298 the correct value for your kernel, boot with normal
1299 autodetection and see what value is printed. Note that
1300 on SMP systems the preset will be applied to all CPUs,
1301 which is likely to cause problems if your CPUs need
1302 significantly divergent settings. An incorrect value
1303 will cause delays in the kernel to be wrong, leading to
1304 unpredictable I/O errors and other breakage. Although
1305 unlikely, in the extreme case this might damage your
1306 hardware.
1307
1308 ltpc= [NET]
1309 Format: <io>,<irq>,<dma>
1310
Randy Dunlapa9913042005-10-23 12:57:11 -07001311 mac5380= [HW,SCSI] Format:
1312 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313
Randy Dunlapa9913042005-10-23 12:57:11 -07001314 machvec= [IA64] Force the use of a particular machine-vector
1315 (machvec) in a generic kernel.
1316 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317
Wu Zhangjin3209e702009-07-02 23:27:12 +08001318 machtype= [Loongson] Share the same kernel image file between different
1319 yeeloong laptop.
1320 Example: machtype=lemote-yeeloong-2f-7inch
1321
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001322 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1323 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324
1325 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001326 should make use of. maxcpus=n : n >= 0 limits the
1327 kernel to using 'n' processors. n=0 is a special case,
1328 it is equivalent to "nosmp", which also disables
1329 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001331 max_loop= [LOOP] Maximum number of loopback devices that can
1332 be mounted
1333 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001334
Randy Dunlapa9913042005-10-23 12:57:11 -07001335 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 Should be between 1 and 2^32-1.
1337
1338 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001339 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 Should be between 1 and 16384.
1341
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 mcatest= [IA-64]
1343
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001344 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345
Uwe Hermann71cced62008-10-20 09:32:21 -07001346 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001347
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 md= [HW] RAID subsystems devices and level
1349 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001350
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 mdacon= [MDA]
1352 Format: <first>,<last>
1353 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1356 Amount of memory to be used when the kernel is not able
1357 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001358 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 address space collisions. Without memmap= PCI devices
1360 could be placed at addresses belonging to unused RAM.
1361
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001362 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 memory.
1364
Paul Mundt6902aa82008-09-21 17:14:42 +09001365 memchunk=nn[KMG]
1366 [KNL,SH] Allow user to override the default size for
1367 per-device physically contiguous DMA buffers.
1368
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301369 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 E820 memory map, as specified by the user.
1371 Such memmap=exactmap lines can be constructed based on
1372 BIOS output or other requirements. See the memmap=nn@ss
1373 option description.
1374
1375 memmap=nn[KMG]@ss[KMG]
1376 [KNL] Force usage of a specific region of memory
1377 Region of memory to be used, from ss to ss+nn.
1378
1379 memmap=nn[KMG]#ss[KMG]
1380 [KNL,ACPI] Mark specific memory as ACPI data.
1381 Region of memory to be used, from ss to ss+nn.
1382
1383 memmap=nn[KMG]$ss[KMG]
1384 [KNL,ACPI] Mark specific memory as reserved.
1385 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001386 Example: Exclude memory from 0x18690000-0x1869ffff
1387 memmap=64K$0x18690000
1388 or
1389 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001391 memory_corruption_check=0/1 [X86]
1392 Some BIOSes seem to corrupt the first 64k of
1393 memory when doing things like suspend/resume.
1394 Setting this option will scan the memory
1395 looking for corruption. Enabling this will
1396 both detect corruption and prevent the kernel
1397 from using the memory being corrupted.
1398 However, its intended as a diagnostic tool; if
1399 repeatable BIOS-originated corruption always
1400 affects the same memory, you can use memmap=
1401 to prevent the kernel from using that memory.
1402
1403 memory_corruption_check_size=size [X86]
1404 By default it checks for corruption in the low
1405 64k, making this memory unavailable for normal
1406 use. Use this parameter to scan for
1407 corruption in more or less memory.
1408
1409 memory_corruption_check_period=seconds [X86]
1410 By default it checks for corruption every 60
1411 seconds. Use this parameter to check at some
1412 other rate. 0 disables periodic checking.
1413
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001414 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001415 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001416 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001417 Specifies the number of memtest passes to be
1418 performed. Each pass selects another test
1419 pattern from a given set of patterns. Memtest
1420 fills the memory with this pattern, validates
1421 memory contents and reserves bad memory
1422 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001423
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 meye.*= [HW] Set MotionEye Camera parameters
1425 See Documentation/video4linux/meye.txt.
1426
Andres Salomon8f368812007-10-12 23:04:06 +02001427 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1428 Multi-Function General Purpose Timers on AMD Geode
1429 platforms.
1430
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001431 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1432 the BIOS has incorrectly applied a workaround. TinyBIOS
1433 version 0.98 is known to be affected, 0.99 fixes the
1434 problem by letting the user disable the workaround.
1435
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 mga= [HW,DRM]
1437
Randy Dunlap1c207f92008-11-19 15:36:16 -08001438 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1439 physical address is ignored.
1440
Michel Pollet39f45d72009-05-20 11:10:31 +01001441 mini2440= [ARM,HW,KNL]
1442 Format:[0..2][b][c][t]
1443 Default: "0tb"
1444 MINI2440 configuration specification:
1445 0 - The attached screen is the 3.5" TFT
1446 1 - The attached screen is the 7" TFT
1447 2 - The VGA Shield is attached (1024x768)
1448 Leaving out the screen size parameter will not load
1449 the TFT driver, and the framebuffer will be left
1450 unconfigured.
1451 b - Enable backlight. The TFT backlight pin will be
1452 linked to the kernel VESA blanking code and a GPIO
1453 LED. This parameter is not necessary when using the
1454 VGA shield.
1455 c - Enable the s3c camera interface.
1456 t - Reserved for enabling touchscreen support. The
1457 touchscreen support is not enabled in the mainstream
1458 kernel as of 2.6.30, a preliminary port can be found
1459 in the "bleeding edge" mini2440 support kernel at
1460 http://repo.or.cz/w/linux-2.6/mini2440.git
1461
Mel Gorman6b74ab92008-07-23 21:26:49 -07001462 mminit_loglevel=
1463 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1464 parameter allows control of the logging verbosity for
1465 the additional memory initialisation checks. A value
1466 of 0 disables mminit logging and a level of 4 will
1467 log everything. Information is printed at KERN_DEBUG
1468 so loglevel=8 may also need to be specified.
1469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 mousedev.tap_time=
1471 [MOUSE] Maximum time between finger touching and
1472 leaving touchpad surface for touch to be considered
1473 a tap and be reported as a left button click (for
1474 touchpads working in absolute mode only).
1475 Format: <msecs>
1476 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1477 reporting absolute coordinates, such as tablets
1478 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1479 reporting absolute coordinates, such as tablets
1480
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301481 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001482 is similar to kernelcore except it specifies the
1483 amount of memory used for migratable allocations.
1484 If both kernelcore and movablecore is specified,
1485 then kernelcore will be at *least* the specified
1486 value but may be more. If movablecore on its own
1487 is specified, the administrator must be careful
1488 that the amount of memory usable for all allocations
1489 is not too small.
1490
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491 mpu401= [HW,OSS]
1492 Format: <io>,<irq>
1493
1494 MTD_Partition= [MTD]
1495 Format: <name>,<region-number>,<size>,<offset>
1496
Randy Dunlapa9913042005-10-23 12:57:11 -07001497 MTD_Region= [MTD] Format:
1498 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499
1500 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001501 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001503 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1504
1505 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1506
1507 boundary - index of last SLC block on Flex-OneNAND.
1508 The remaining blocks are configured as MLC blocks.
1509 lock - Configure if Flex-OneNAND boundary should be locked.
1510 Once locked, the boundary cannot be changed.
1511 1 indicates lock status, 0 indicates unlock status.
1512
Ben Dooks9db829f2008-07-03 11:24:29 +01001513 mtdset= [ARM]
1514 ARM/S3C2412 JIVE boot control
1515
1516 See arch/arm/mach-s3c2412/mach-jive.c
1517
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001519 [HW] Make the MicroTouch USB driver use raw coordinates
1520 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001522 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001523 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001524 that could hold holes aka. UC entries.
1525
1526 mtrr_gran_size=nn[KMG] [X86]
1527 Used for mtrr cleanup. It is granularity of mtrr block.
1528 Default is 1.
1529 Large value could prevent small alignment from
1530 using up MTRRs.
1531
1532 mtrr_spare_reg_nr=n [X86]
1533 Format: <integer>
1534 Range: 0,7 : spare reg number
1535 Default : 1
1536 Used for mtrr cleanup. It is spare mtrr entries number.
1537 Set to 2 or more if your graphical card needs more.
1538
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1540
1541 NCR_D700= [HW,SCSI]
1542 See header of drivers/scsi/NCR_D700.c.
1543
1544 ncr5380= [HW,SCSI]
1545
1546 ncr53c400= [HW,SCSI]
1547
1548 ncr53c400a= [HW,SCSI]
1549
1550 ncr53c406a= [HW,SCSI]
1551
1552 ncr53c8xx= [HW,SCSI]
1553
1554 netdev= [NET] Network devices parameters
1555 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1556 Note that mem_start is often overloaded to mean
1557 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001558 This usage is only documented in each driver source
1559 file if at all.
1560
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001561 nf_conntrack.acct=
1562 [NETFILTER] Enable connection tracking flow accounting
1563 0 to disable accounting
1564 1 to enable accounting
1565 Default value depends on CONFIG_NF_CT_ACCT that is
1566 going to be removed in 2.6.29.
1567
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001569 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
1571 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001572 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573
Trond Myklebusta72b4422006-01-03 09:55:41 +01001574 nfs.callback_tcpport=
1575 [NFS] set the TCP port on which the NFSv4 callback
1576 channel should listen.
1577
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001578 nfs.cache_getent=
1579 [NFS] sets the pathname to the program which is used
1580 to update the NFS client cache entries.
1581
1582 nfs.cache_getent_timeout=
1583 [NFS] sets the timeout after which an attempt to
1584 update a cache entry is deemed to have failed.
1585
Trond Myklebust58df0952006-01-03 09:55:57 +01001586 nfs.idmap_cache_timeout=
1587 [NFS] set the maximum lifetime for idmapper cache
1588 entries.
1589
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001590 nfs.enable_ino64=
1591 [NFS] enable 64-bit inode numbers.
1592 If zero, the NFS client will fake up a 32-bit inode
1593 number for the readdir() and stat() syscalls instead
1594 of returning the full 64-bit number.
1595 The default is to return 64-bit inode numbers.
1596
Paul Mundt1e1030d2009-09-01 17:38:32 +09001597 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001598 when a NMI is triggered.
1599 Format: [state][,regs][,debounce][,die]
1600
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301601 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001602 Format: [panic,][num]
1603 Valid num: 0,1,2
1604 0 - turn nmi_watchdog off
1605 1 - use the IO-APIC timer for the NMI watchdog
1606 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001607 a performance counter. Note: This will use one
1608 performance counter and the local APIC's performance
1609 vector.
1610 When panic is specified, panic when an NMI watchdog
1611 timeout occurs.
1612 This is useful when you use a panic=... timeout and
1613 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001614 Instead of 1 and 2 it is possible to use the following
1615 symbolic names: lapic and ioapic
1616 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617
Anton Vorontsovbff38772009-07-08 11:10:56 -07001618 netpoll.carrier_timeout=
1619 [NET] Specifies amount of time (in seconds) that
1620 netpoll should wait for a carrier. By default netpoll
1621 waits 4 seconds.
1622
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001623 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 emulation library even if a 387 maths coprocessor
1625 is present.
1626
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001627 no_console_suspend
1628 [HW] Never suspend the console
1629 Disable suspending of consoles during suspend and
1630 hibernate operations. Once disabled, debugging
1631 messages can reach various consoles while the rest
1632 of the system is being put to sleep (ie, while
1633 debugging driver suspend/resume hooks). This may
1634 not work reliably with all consoles, but is known
1635 to work with serial and VGA consoles.
1636
Christoph Lameterc1aee212007-05-31 00:40:47 -07001637 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1638 caches in the slab allocator. Saves per-node memory,
1639 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001640
Randy Dunlapa9913042005-10-23 12:57:11 -07001641 noalign [KNL,ARM]
1642
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643 noapic [SMP,APIC] Tells the kernel to not make use of any
1644 IOAPICs that may be present in the system.
1645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 nobats [PPC] Do not use BATs for mapping kernel lowmem
1647 on "Classic" PPC cores.
1648
1649 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001650
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001651 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1652
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001653 nodelayacct [KNL] Disable per-task delay accounting
1654
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1656
Paul Mundt6902aa82008-09-21 17:14:42 +09001657 nodsp [SH] Disable hardware DSP at boot time.
1658
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301659 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001660
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 noexec [IA-64]
1662
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301663 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001664 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001666 noexec=off: disable non-executable mappings
1667
1668 noexec32 [X86-64]
1669 This affects only 32-bit executables.
1670 noexec32=on: enable non-executable mappings (default)
1671 read doesn't imply executable mappings
1672 noexec32=off: disable non-executable mappings
1673 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674
Paul Mundt6902aa82008-09-21 17:14:42 +09001675 nofpu [SH] Disable hardware FPU at boot time.
1676
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001677 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001678 register save and restore. The kernel will only save
1679 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680
Suresh Siddha0c752a92009-05-22 12:17:45 -07001681 noxsave [BUGS=X86] Disables x86 extended register state save
1682 and restore using xsave. The kernel will fallback to
1683 enabling legacy floating-point and sse state.
1684
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001685 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1686 wfi(ARM) instruction doesn't work correctly and not to
1687 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001688
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001689 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 instruction doesn't work correctly and not to
1691 use it.
1692
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001693 no_file_caps Tells the kernel not to honor file capabilities. The
1694 only way then for a file to be executed with privilege
1695 is to be setuid root or executed by root.
1696
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 nohalt [IA-64] Tells the kernel not to use the power saving
1698 function PAL_HALT_LIGHT when idle. This increases
1699 power-consumption. On the positive side, it reduces
1700 interrupt wake-up latency, which may improve performance
1701 in certain environments such as networked servers or
1702 real-time systems.
1703
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001704 nohz= [KNL] Boottime enable/disable dynamic ticks
1705 Valid arguments: on, off
1706 Default: on
1707
Paul Mundteeee7852009-04-02 12:31:16 +09001708 noiotrap [SH] Disables trapped I/O port accesses.
1709
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001710 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 disable unhandled interrupt sources.
1712
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301713 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001714 broken timer IRQ sources.
1715
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 noisapnp [ISAPNP] Disables ISA PnP code.
1717
1718 noinitrd [RAM] Tells the kernel not to load any configured
1719 initial RAM disk.
1720
Weidong Han03ea8152009-04-17 16:42:15 +08001721 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1722 remapping.
1723
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724 nointroute [IA-64]
1725
Tony Luck0aa366f2007-07-20 11:22:30 -07001726 nojitter [IA64] Disables jitter checking for ITC timers.
1727
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001728 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001730 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001731
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 noltlbs [PPC] Do not use large page/tlb entries for kernel
1733 lowmem mapping on PPC40x.
1734
Horms312f1f02006-02-22 09:57:55 +09001735 nomca [IA-64] Disable machine check abort handling
1736
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001737 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001738
Andres Salomon83d73842007-10-12 23:04:06 +02001739 nomfgpt [X86-32] Disable Multi-Function General Purpose
1740 Timer usage (for AMD Geode machines).
1741
Jiri Kosina016ddd92010-01-18 17:05:40 +01001742 nopat [X86] Disable PAT (page attribute table extension of
1743 pagetables) support.
1744
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001745 norandmaps Don't use address space randomization. Equivalent to
1746 echo 0 > /proc/sys/kernel/randomize_va_space
1747
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001748 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001749
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001750 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001751 with UP alternatives
1752
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753 noresidual [PPC] Don't use residual data on PReP machines.
1754
Randy Dunlapa9913042005-10-23 12:57:11 -07001755 noresume [SWSUSP] Disables resume and restores original swap
1756 space.
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 no-scroll [VGA] Disables scrollback.
1759 This is required for the Braillex ib80-piezo Braille
1760 reader made by F.H. Papenmeier (Germany).
1761
1762 nosbagart [IA-64]
1763
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001765
Len Brown61ec7562007-08-16 03:34:22 -04001766 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1767 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768
Dave Jones97842212007-07-15 23:41:05 -07001769 nosoftlockup [KNL] Disable the soft-lockup detector.
1770
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001771 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001772 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001773
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 nosync [HW,M68K] Disables sync negotiation for all devices.
1775
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001776 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777
1778 nousb [USB] Disable the USB subsystem
1779
1780 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001781
Weidong Han2b2fd872009-04-17 16:42:12 +08001782 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1783
Fenghua Yua6c75b862008-03-14 13:57:08 -07001784 nptcg= [IA64] Override max number of concurrent global TLB
1785 purges which is reported from either PAL_VM_SUMMARY or
1786 SAL PALO.
1787
Yinghai Lu2b633e32010-02-10 01:20:37 -08001788 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1789 could support. nr_cpus=n : n >= 1 limits the kernel to
1790 supporting 'n' processors. Later in runtime you can not
1791 use hotplug cpu feature to put more cpu back to online.
1792 just like you compile the kernel NR_CPUS=n
1793
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001794 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1795
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001796 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1797 one of ['zone', 'node', 'default'] can be specified
1798 This can be set from sysctl after boot.
1799 See Documentation/sysctl/vm.txt for details.
1800
Randy Dunlap7c4be252009-01-06 14:42:44 -08001801 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1802 See Documentation/debugging-via-ohci1394.txt for more
1803 info.
1804
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001805 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1806 Rather than timing out after 20 ms if an EC
1807 command is not properly ACKed, override the length
1808 of the timeout. We have interrupts disabled while
1809 waiting for the ACK, so if this is set too high
1810 interrupts *may* be lost!
1811
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001812 omap_mux= [OMAP] Override bootloader pin multiplexing.
1813 Format: <mux_mode0.mode_name=value>...
1814 For example, to override I2C bus2:
1815 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1816
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817 opl3= [HW,OSS]
1818 Format: <io>
1819
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820 oprofile.timer= [HW]
1821 Use timer interrupt instead of performance counters
1822
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001823 oprofile.cpu_type= Force an oprofile cpu type
1824 This might be useful if you have an older oprofile
1825 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001826 Format: { arch_perfmon }
1827 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001828 perfmon on Intel CPUs instead of the
1829 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001830
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 osst= [HW,SCSI] SCSI Tape Driver
1832 Format: <buffer_size>,<write_threshold>
1833 See also Documentation/scsi/st.txt.
1834
1835 panic= [KNL] Kernel behaviour on panic
1836 Format: <timeout>
1837
1838 parkbd.port= [HW] Parallel port number the keyboard adapter is
1839 connected to, default is 0.
1840 Format: <parport#>
1841 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1842 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001843 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844
Randy Dunlapa9913042005-10-23 12:57:11 -07001845 parport= [HW,PPT] Specify parallel ports. 0 disables.
1846 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1847 Use 'auto' to force the driver to use any
1848 IRQ/DMA settings detected (the default is to
1849 ignore detected IRQ/DMA settings because of
1850 possible conflicts). You can specify the base
1851 address, IRQ, and DMA settings; IRQ and DMA
1852 should be numbers, or 'auto' (for using detected
1853 settings on that particular port), or 'nofifo'
1854 (to avoid using a FIFO even if it is detected).
1855 Parallel ports are assigned in the order they
1856 are specified on the command line, starting
1857 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858
Randy Dunlapa9913042005-10-23 12:57:11 -07001859 parport_init_mode= [HW,PPT]
1860 Configure VIA parallel port to operate in
1861 a specific mode. This is necessary on Pegasos
1862 computer where firmware has no options for setting
1863 up parallel port mode and sets it to spp.
1864 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 Format: [spp|ps2|epp|ecp|ecpepp]
1866
Randy Dunlapa9913042005-10-23 12:57:11 -07001867 pas2= [HW,OSS] Format:
1868 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1869
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870 pas16= [HW,SCSI]
1871 See header of drivers/scsi/pas16.c.
1872
Andrew Mortondd287792006-03-23 03:00:57 -08001873 pause_on_oops=
1874 Halt all CPUs after the first oops has been printed for
1875 the specified number of seconds. This is to be used if
1876 your oopses keep scrolling off the screen.
1877
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 pcbit= [HW,ISDN]
1879
1880 pcd. [PARIDE]
1881 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001882 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883
Randy Dunlapa9913042005-10-23 12:57:11 -07001884 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001885 earlydump [X86] dump PCI config space before the kernel
1886 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001887 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001888 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001889 the hardware directly. Use this if your machine
1890 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001891 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001892 hardware access methods are allowed. Use this
1893 if you experience crashes upon bootup and you
1894 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001895 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001896 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001897 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001898 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001899 noaer [PCIE] If the PCIEAER kernel config parameter is
1900 enabled, this kernel boot option can be used to
1901 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001902 nodomains [PCI] Disable support for multiple PCI
1903 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301904 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001905 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001906 check_enable_amd_mmconf [X86] check for and enable
1907 properly configured MMIO access to PCI
1908 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001909 nomsi [MSI] If the PCI_MSI kernel config parameter is
1910 enabled, this kernel boot option can be used to
1911 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001912 noioapicquirk [APIC] Disable all boot interrupt quirks.
1913 Safety option to keep boot IRQs enabled. This
1914 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001915 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1916 primary IO-APIC for bridges that cannot disable
1917 boot IRQs. This fixes a source of spurious IRQs
1918 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001919 noioapicreroute [APIC] Disable workaround that uses the
1920 boot IRQ equivalent of an IRQ that connects to
1921 a chipset where boot IRQs cannot be disabled.
1922 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001923 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001924 routing table. These calls are known to be buggy
1925 on several machines and they hang the machine
1926 when used, but on other computers it's the only
1927 way to get the interrupt routing table. Try
1928 this option if the kernel is unable to allocate
1929 IRQs or discover secondary PCI buses on your
1930 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001931 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001932 Use with caution as certain devices share
1933 address decoders between ROMs and other
1934 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001935 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001936 expansion ROMs that do not already have
1937 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001938 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001939 assigned automatically to PCI devices. You can
1940 make the kernel exclude IRQs of your ISA cards
1941 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001942 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001943 of the PIRQ table (normally generated
1944 by the BIOS) if it is outside the
1945 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001946 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001947 useful if the kernel is unable to find your
1948 secondary buses and you want to tell it
1949 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001950 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001951 numbers ourselves, overriding
1952 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001953 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001954 in the BIOS $PIR table. This is needed on
1955 some systems with broken BIOSes, notably
1956 some HP Pavilion N5400 and Omnibook XE3
1957 notebooks. This will have no effect if ACPI
1958 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001959 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001960 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001961 use_crs [X86] Use PCI host bridge window information
1962 from ACPI. On BIOSes from 2008 or later, this
1963 is enabled by default. If you need to use this,
1964 please report a bug.
1965 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1966 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001967 routeirq Do IRQ routing for all PCI devices.
1968 This is normally done in pci_enable_device(),
1969 so this option is a temporary workaround
1970 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001971 skip_isa_align [X86] do not align io start addr, so can
1972 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001973 firmware [ARM] Do not re-enumerate the bus but instead
1974 just use the configuration from the
1975 bootloader. This is currently used on
1976 IXP2000 systems where the bus has to be
1977 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001978 noearly [X86] Don't do any early type 1 scanning.
1979 This might help on some broken boards which
1980 machine check when some devices' config space
1981 is read. But various workarounds are disabled
1982 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001983 bfsort Sort PCI devices into breadth-first order.
1984 This sorting is done to get a device
1985 order compatible with older (<= 2.4) kernels.
1986 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001987 cbiosize=nn[KMG] The fixed amount of bus space which is
1988 reserved for the CardBus bridge's IO window.
1989 The default value is 256 bytes.
1990 cbmemsize=nn[KMG] The fixed amount of bus space which is
1991 reserved for the CardBus bridge's memory
1992 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09001993 resource_alignment=
1994 Format:
1995 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1996 Specifies alignment and device to reassign
1997 aligned memory resources.
1998 If <order of align> is not specified,
1999 PAGE_SIZE is used as alignment.
2000 PCI-PCI bridge can be specified, if resource
2001 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002002 ecrc= Enable/disable PCIe ECRC (transaction layer
2003 end-to-end CRC checking).
2004 bios: Use BIOS/firmware settings. This is the
2005 the default.
2006 off: Turn ECRC off
2007 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002008
Chuck Ebberte5665a42008-09-24 20:40:34 -04002009 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2010 Management.
2011 off Disable ASPM.
2012 force Enable ASPM even on devices that claim not to support it.
2013 WARNING: Forcing ASPM on may cause system lockups.
2014
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002015 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2016 off Do not use native PCIe PME signaling.
2017 force Use native PCIe PME signaling even if the BIOS refuses
2018 to allow the kernel to control the relevant PCIe config
2019 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002020 nomsi Do not use MSI for native PCIe PME signaling (this makes
2021 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002022
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 pcmv= [HW,PCMCIA] BadgePAD 4
2024
2025 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002026 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027
2028 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2029 boot time.
2030 Format: { 0 | 1 }
2031 See arch/parisc/kernel/pdc_chassis.c
2032
Tejun Heof58dc012009-08-14 15:00:50 +09002033 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002034 Currently supported values are "embed" and "page".
2035 Archs may support subset or none of the selections.
2036 See comments in mm/percpu.c for details on each
2037 allocator. This parameter is primarily for debugging
2038 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002039
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002041 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042
2043 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002044 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045
2046 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002047 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048
2049 plip= [PPT,NET] Parallel port network link
2050 Format: { parport<nr> | timid | 0 }
2051 See also Documentation/parport.txt.
2052
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002053 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2054 Override pmtimer IOPort with a hex value.
2055 e.g. pmtmr=0x508
2056
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002057 pnp.debug [PNP]
2058 Enable PNP debug messages. This depends on the
2059 CONFIG_PNP_DEBUG_MESSAGES option.
2060
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 pnpacpi= [ACPI]
2062 { off }
2063
2064 pnpbios= [ISAPNP]
2065 { on | off | curr | res | no-curr | no-res }
2066
2067 pnp_reserve_irq=
2068 [ISAPNP] Exclude IRQs for the autoconfiguration
2069
2070 pnp_reserve_dma=
2071 [ISAPNP] Exclude DMAs for the autoconfiguration
2072
2073 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002074 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075
2076 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002077 [ISAPNP] Exclude memory regions for the
2078 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079 Ranges are in pairs (memory base and size).
2080
Randy Dunlap4af94f32009-04-17 18:30:28 -07002081 ports= [IP_VS_FTP] IPVS ftp helper module
2082 Default is 21.
2083 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2084 may be specified.
2085 Format: <port>,<port>....
2086
Ingo Molnar45807a12007-07-15 23:40:10 -07002087 print-fatal-signals=
2088 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002089
2090 If enabled, warn about various signal handling
2091 related application anomalies: too many signals,
2092 too many POSIX.1 timers, fatal signals causing a
2093 coredump - etc.
2094
2095 If you hit the warning due to signal overflow,
2096 you might want to try "ulimit -i unlimited".
2097
Ingo Molnar45807a12007-07-15 23:40:10 -07002098 default: off.
2099
Randy Dunlape84845c2007-07-15 23:40:25 -07002100 printk.time= Show timing data prefixed to each printk message line
2101 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2102
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002103 processor.max_cstate= [HW,ACPI]
2104 Limit processor to maximum C-state
2105 max_cstate=9 overrides any DMI blacklist limit.
2106
2107 processor.nocst [HW,ACPI]
2108 Ignore the _CST method to determine C-states,
2109 instead using the legacy FADT method
2110
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002112 Format: [schedule,]<number>
2113 Param: "schedule" - profile schedule points.
2114 Param: <number> - step/bucket size as a power of 2 for
2115 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002116 Param: "sleep" - profile D-state sleeping (millisecs).
2117 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002118 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2121 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002122 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123
Randy Dunlapa9913042005-10-23 12:57:11 -07002124 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2125 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2127 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002128 psmouse.resetafter= [HW,MOUSE]
2129 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130 (0 = never).
2131 psmouse.resolution=
2132 [HW,MOUSE] Set desired mouse resolution, in dpi.
2133 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002134 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135 0 = disabled, 1 = enabled (default).
2136
2137 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002138 Format:
2139 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140
2141 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002142 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
Kay Sieversdc8c8582007-08-15 12:25:38 +02002144 pty.legacy_count=
2145 [KNL] Number of legacy pty's. Overwrites compiled-in
2146 default number.
2147
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002148 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002149
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 r128= [HW,DRM]
2151
2152 raid= [HW,RAID]
2153 See Documentation/md.txt.
2154
Randy Dunlapa9913042005-10-23 12:57:11 -07002155 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002156 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002157
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002159 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002161 rcupdate.blimit= [KNL,BOOT]
2162 Set maximum number of finished RCU callbacks to process
2163 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002164
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002165 rcupdate.qhimark= [KNL,BOOT]
2166 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002167 RCU callbacks over which batch limiting is disabled.
2168
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002169 rcupdate.qlowmark= [KNL,BOOT]
2170 Set threshold of queued RCU callbacks below which
2171 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002172
Olof Johanssonffdfc402005-09-06 15:17:19 -07002173 rdinit= [KNL]
2174 Format: <full_path>
2175 Run specified binary instead of /init from the ramdisk,
2176 used for early userspace startup. See initrd.
2177
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002178 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002180 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181
Paul Jackson46b6d942008-07-04 10:00:09 -07002182 relax_domain_level=
2183 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002184 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002185
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2187
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002188 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002189 Format: nn[KMG]
2190 Reserves a hole at the top of the kernel virtual
2191 address space.
2192
Vivek Goyal7e962872006-09-27 01:50:44 -07002193 reset_devices [KNL] Force drivers to reset the underlying device
2194 during initialization.
2195
Randy Dunlapa9913042005-10-23 12:57:11 -07002196 resume= [SWSUSP]
2197 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002199 resume_offset= [SWSUSP]
2200 Specify the offset from the beginning of the partition
2201 given by "resume=" at which the swap header is located,
2202 in <PAGE_SIZE> units (needed only for swap files).
2203 See Documentation/power/swsusp-and-swap-files.txt
2204
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002205 retain_initrd [RAM] Keep initrd memory after extraction
2206
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 rhash_entries= [KNL,NET]
2208 Set number of hash buckets for route cache
2209
2210 riscom8= [HW,SERIAL]
2211 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2212
2213 ro [KNL] Mount root device read-only on boot
2214
2215 root= [KNL] Root filesystem
2216
2217 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2218 mount the root filesystem
2219
2220 rootflags= [KNL] Set root filesystem mount option string
2221
2222 rootfstype= [KNL] Set root filesystem type
2223
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002224 rootwait [KNL] Wait (indefinitely) for root device to show up.
2225 Useful for devices that are detected asynchronously
2226 (e.g. USB and MMC devices).
2227
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228 rw [KNL] Mount root device read-write on boot
2229
2230 S [KNL] Run init in single mode
2231
2232 sa1100ir [NET]
2233 See drivers/net/irda/sa1100_ir.c.
2234
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002236
Mike Travisf6630112009-11-17 18:22:15 -06002237 sched_debug [KNL] Enables verbose scheduler debug messages.
2238
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2240 Format: <io>[,<timeout>[,<isapnp>]]
2241
2242 scsi_debug_*= [SCSI]
2243 See drivers/scsi/scsi_debug.c.
2244
2245 scsi_default_dev_flags=
2246 [SCSI] SCSI default device flags
2247 Format: <integer>
2248
2249 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2250 Format: <vendor>:<model>:<flags>
2251 (flags are integer value)
2252
Randy Dunlap6af66322007-11-14 16:52:25 -08002253 scsi_logging_level= [SCSI] a bit mask of logging levels
2254 See drivers/scsi/scsi_logging.h for bits. Also
2255 settable via sysctl at dev.scsi.logging_level
2256 (/proc/sys/dev/scsi/logging_level).
2257 There is also a nice 'scsi_logging_level' script in the
2258 S390-tools package, available for download at
2259 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002261 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2262 discovered. async scans them in kernel threads,
2263 allowing boot to proceed. none ignores them, expecting
2264 user space to do the scan.
2265
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002266 security= [SECURITY] Choose a security module to enable at boot.
2267 If this boot parameter is not specified, only the first
2268 security module asking for security registration will be
2269 loaded. An invalid security module name will be treated
2270 as if no module has been chosen.
2271
2272 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273 Format: { "0" | "1" }
2274 See security/selinux/Kconfig help text.
2275 0 -- disable.
2276 1 -- enable.
2277 Default value is set via kernel config option.
2278 If enabled at boot time, /selinux/disable can be used
2279 later to disable prior to initial policy load.
2280
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002281 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283 shapers= [NET]
2284 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002285
Yinghai Lub05f78f2008-08-22 01:32:50 -07002286 show_msr= [x86] show boot-time MSR settings
2287 Format: { <integer> }
2288 Show boot-time (BIOS-initialized) MSR settings.
2289 The parameter means the number of CPUs to show,
2290 for example 1 means boot CPU only.
2291
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292 sim710= [SCSI,HW]
2293 See header of drivers/scsi/sim710.c.
2294
2295 simeth= [IA-64]
2296 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002297
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298 slram= [HW,MTD]
2299
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002300 slub_debug[=options[,slabs]] [MM, SLUB]
2301 Enabling slub_debug allows one to determine the
2302 culprit if slab objects become corrupted. Enabling
2303 slub_debug can create guard zones around objects and
2304 may poison objects when not in use. Also tracks the
2305 last alloc / free. For more information see
2306 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002307
2308 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002309 Determines the maximum allowed order for slabs.
2310 A high setting may cause OOMs due to memory
2311 fragmentation. For more information see
2312 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002313
2314 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002315 The minimum number of objects per slab. SLUB will
2316 increase the slab order up to slub_max_order to
2317 generate a sufficiently large slab able to contain
2318 the number of objects indicated. The higher the number
2319 of objects the smaller the overhead of tracking slabs
2320 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002321 For more information see Documentation/vm/slub.txt.
2322
2323 slub_min_order= [MM, SLUB]
2324 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002325 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002326 For more information see Documentation/vm/slub.txt.
2327
2328 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002329 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002330 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002331 allocs to different slabs. Debug options disable
2332 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002333 For more information see Documentation/vm/slub.txt.
2334
Linus Torvalds1da177e2005-04-16 15:20:36 -07002335 smart2= [HW]
2336 Format: <io1>[,<io2>[,...,<io8>]]
2337
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002338 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002339 attempt to substitute SMP alternatives once at boot.
2340
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002341 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2342 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2343 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2344 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2345 smsc-ircc2.ircc_irq= [HW] IRQ line
2346 smsc-ircc2.ircc_dma= [HW] DMA channel
2347 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2348 0: Toshiba Satellite 1800 (GP data pin select)
2349 1: Fast pin select (default)
2350 2: ATC IRMode
2351
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352 snd-ad1816a= [HW,ALSA]
2353
2354 snd-ad1848= [HW,ALSA]
2355
2356 snd-ali5451= [HW,ALSA]
2357
2358 snd-als100= [HW,ALSA]
2359
2360 snd-als4000= [HW,ALSA]
2361
2362 snd-azt2320= [HW,ALSA]
2363
2364 snd-cmi8330= [HW,ALSA]
2365
2366 snd-cmipci= [HW,ALSA]
2367
2368 snd-cs4231= [HW,ALSA]
2369
2370 snd-cs4232= [HW,ALSA]
2371
2372 snd-cs4236= [HW,ALSA]
2373
2374 snd-cs4281= [HW,ALSA]
2375
2376 snd-cs46xx= [HW,ALSA]
2377
2378 snd-dt019x= [HW,ALSA]
2379
2380 snd-dummy= [HW,ALSA]
2381
2382 snd-emu10k1= [HW,ALSA]
2383
2384 snd-ens1370= [HW,ALSA]
2385
2386 snd-ens1371= [HW,ALSA]
2387
2388 snd-es968= [HW,ALSA]
2389
2390 snd-es1688= [HW,ALSA]
2391
2392 snd-es18xx= [HW,ALSA]
2393
2394 snd-es1938= [HW,ALSA]
2395
2396 snd-es1968= [HW,ALSA]
2397
2398 snd-fm801= [HW,ALSA]
2399
2400 snd-gusclassic= [HW,ALSA]
2401
2402 snd-gusextreme= [HW,ALSA]
2403
2404 snd-gusmax= [HW,ALSA]
2405
2406 snd-hdsp= [HW,ALSA]
2407
2408 snd-ice1712= [HW,ALSA]
2409
2410 snd-intel8x0= [HW,ALSA]
2411
2412 snd-interwave= [HW,ALSA]
2413
2414 snd-interwave-stb=
2415 [HW,ALSA]
2416
2417 snd-korg1212= [HW,ALSA]
2418
2419 snd-maestro3= [HW,ALSA]
2420
2421 snd-mpu401= [HW,ALSA]
2422
2423 snd-mtpav= [HW,ALSA]
2424
2425 snd-nm256= [HW,ALSA]
2426
2427 snd-opl3sa2= [HW,ALSA]
2428
2429 snd-opti92x-ad1848=
2430 [HW,ALSA]
2431
2432 snd-opti92x-cs4231=
2433 [HW,ALSA]
2434
2435 snd-opti93x= [HW,ALSA]
2436
2437 snd-pmac= [HW,ALSA]
2438
2439 snd-rme32= [HW,ALSA]
2440
2441 snd-rme96= [HW,ALSA]
2442
2443 snd-rme9652= [HW,ALSA]
2444
2445 snd-sb8= [HW,ALSA]
2446
2447 snd-sb16= [HW,ALSA]
2448
2449 snd-sbawe= [HW,ALSA]
2450
2451 snd-serial= [HW,ALSA]
2452
2453 snd-sgalaxy= [HW,ALSA]
2454
2455 snd-sonicvibes= [HW,ALSA]
2456
2457 snd-sun-amd7930=
2458 [HW,ALSA]
2459
2460 snd-sun-cs4231= [HW,ALSA]
2461
2462 snd-trident= [HW,ALSA]
2463
2464 snd-usb-audio= [HW,ALSA,USB]
2465
2466 snd-via82xx= [HW,ALSA]
2467
2468 snd-virmidi= [HW,ALSA]
2469
2470 snd-wavefront= [HW,ALSA]
2471
2472 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002473
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002474 softlockup_panic=
2475 [KNL] Should the soft-lockup detector generate panics.
2476
Linus Torvalds1da177e2005-04-16 15:20:36 -07002477 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2478 See Documentation/sonypi.txt
2479
2480 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002481 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482
2483 spia_io_base= [HW,MTD]
2484 spia_fio_base=
2485 spia_pedr=
2486 spia_peddr=
2487
2488 sscape= [HW,OSS]
2489 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002490
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2492 See Documentation/scsi/st.txt.
2493
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002494 stacktrace [FTRACE]
2495 Enabled the stack tracer on boot up.
2496
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497 sti= [PARISC,HW]
2498 Format: <num>
2499 Set the STI (builtin display/keyboard on the HP-PARISC
2500 machines) console (graphic card) which should be used
2501 as the initial boot-console.
2502 See also comment in drivers/video/console/sticore.c.
2503
2504 sti_font= [HW]
2505 See comment in drivers/video/console/sticore.c.
2506
2507 stifb= [HW]
2508 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2509
Trond Myklebustcbf11072009-08-09 15:06:19 -04002510 sunrpc.min_resvport=
2511 sunrpc.max_resvport=
2512 [NFS,SUNRPC]
2513 SunRPC servers often require that client requests
2514 originate from a privileged port (i.e. a port in the
2515 range 0 < portnr < 1024).
2516 An administrator who wishes to reserve some of these
2517 ports for other uses may adjust the range that the
2518 kernel's sunrpc client considers to be privileged
2519 using these two parameters to set the minimum and
2520 maximum port values.
2521
Greg Banks42a7fc42007-03-06 01:42:23 -08002522 sunrpc.pool_mode=
2523 [NFS]
2524 Control how the NFS server code allocates CPUs to
2525 service thread pools. Depending on how many NICs
2526 you have and where their interrupts are bound, this
2527 option will affect which CPUs will do NFS serving.
2528 Note: this parameter cannot be changed while the
2529 NFS server is running.
2530
2531 auto the server chooses an appropriate mode
2532 automatically using heuristics
2533 global a single global pool contains all CPUs
2534 percpu one pool for each CPU
2535 pernode one pool for each NUMA node (equivalent
2536 to global on non-NUMA machines)
2537
Trond Myklebustcbf11072009-08-09 15:06:19 -04002538 sunrpc.tcp_slot_table_entries=
2539 sunrpc.udp_slot_table_entries=
2540 [NFS,SUNRPC]
2541 Sets the upper limit on the number of simultaneous
2542 RPC calls that can be sent from the client to a
2543 server. Increasing these values may allow you to
2544 improve throughput, but will also increase the
2545 amount of memory reserved for use by the client.
2546
Linus Torvalds1da177e2005-04-16 15:20:36 -07002547 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002548
Linus Torvalds1da177e2005-04-16 15:20:36 -07002549 switches= [HW,M68k]
2550
2551 sym53c416= [HW,SCSI]
2552 See header of drivers/scsi/sym53c416.c.
2553
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002554 sysrq_always_enabled
2555 [KNL]
2556 Ignore sysrq setting - this boot parameter will
2557 neutralize any effect of /proc/sys/kernel/sysrq.
2558 Useful for debugging.
2559
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560 t128= [HW,SCSI]
2561 See header of drivers/scsi/t128.c.
2562
2563 tdfx= [HW,DRM]
2564
David Brownell77437fd2008-07-23 21:28:33 -07002565 test_suspend= [SUSPEND]
2566 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2567 standby suspend) as the system sleep state to briefly
2568 enter during system startup. The system is woken from
2569 this state using a wakeup-capable RTC alarm.
2570
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 thash_entries= [KNL,NET]
2572 Set number of hash buckets for TCP connection
2573
Len Brownf8707ec2007-08-12 00:12:54 -04002574 thermal.act= [HW,ACPI]
2575 -1: disable all active trip points in all thermal zones
2576 <degrees C>: override all lowest active trip points
2577
Len Brownc52a7412007-08-14 15:49:32 -04002578 thermal.crt= [HW,ACPI]
2579 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002580 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002581
Len Brownf5487142007-08-12 00:12:44 -04002582 thermal.nocrt= [HW,ACPI]
2583 Set to disable actions on ACPI thermal zone
2584 critical and hot trip points.
2585
Len Brown72b33ef2007-08-12 00:12:17 -04002586 thermal.off= [HW,ACPI]
2587 1: disable ACPI thermal control
2588
Len Browna70cdc52007-08-12 00:12:35 -04002589 thermal.psv= [HW,ACPI]
2590 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002591 <degrees C>: override all passive trip points to this
2592 value
Len Browna70cdc52007-08-12 00:12:35 -04002593
Len Brown730ff342007-08-12 00:12:26 -04002594 thermal.tzp= [HW,ACPI]
2595 Specify global default ACPI thermal zone polling rate
2596 <deci-seconds>: poll all this frequency
2597 0: no polling (default)
2598
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 tmscsim= [HW,SCSI]
2600 See comment before function dc390_setup() in
2601 drivers/scsi/tmscsim.c.
2602
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002603 topology= [S390]
2604 Format: {off | on}
2605 Specify if the kernel should make use of the cpu
2606 topology informations if the hardware supports these.
2607 The scheduler will make use of these informations and
2608 e.g. base its process migration decisions on it.
2609 Default is off.
2610
Linus Torvalds1da177e2005-04-16 15:20:36 -07002611 tp720= [HW,PS2]
2612
Li Zefan9d612be2009-06-24 17:33:15 +08002613 trace_buf_size=nn[KMG]
2614 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002615
Li Zefan020e5f82009-07-01 10:47:05 +08002616 trace_event=[event-list]
2617 [FTRACE] Set and start specified trace events in order
2618 to facilitate early boot debugging.
2619 See also Documentation/trace/events.txt
2620
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002622 Format:
2623 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2624
Alok Kataria395628e2008-10-24 17:22:01 -07002625 tsc= Disable clocksource-must-verify flag for TSC.
2626 Format: <string>
2627 [x86] reliable: mark tsc clocksource as reliable, this
2628 disables clocksource verification at runtime.
2629 Used to enable high-resolution timer mode on older
2630 hardware, and in virtualized environment.
2631
Randy Dunlapa9913042005-10-23 12:57:11 -07002632 turbografx.map[2|3]= [HW,JOY]
2633 TurboGraFX parallel port interface
2634 Format:
2635 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636 See also Documentation/input/joystick-parport.txt
2637
2638 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2639 See header of drivers/scsi/u14-34f.c.
2640
2641 uart401= [HW,OSS]
2642 Format: <io>,<irq>
2643
2644 uart6850= [HW,OSS]
2645 Format: <io>,<irq>
2646
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002647 uhash_entries= [KNL,NET]
2648 Set number of hash buckets for UDP/UDP-Lite connections
2649
Alan Stern5f8364b2006-12-05 16:29:55 -05002650 uhci-hcd.ignore_oc=
2651 [USB] Ignore overcurrent events (default N).
2652 Some badly-designed motherboards generate lots of
2653 bogus events, for ports that aren't wired to
2654 anything. Set this parameter to avoid log spamming.
2655 Note that genuine overcurrent events won't be
2656 reported either.
2657
Simon Arlotte3a61b02008-07-19 23:32:54 +01002658 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302659 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002660 Set unknown_nmi_panic=1 early on boot.
2661
Alan Sternb5e795f2007-02-20 15:00:53 -05002662 usbcore.autosuspend=
2663 [USB] The autosuspend time delay (in seconds) used
2664 for newly-detected USB devices (default 2). This
2665 is the time required before an idle device will be
2666 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002667 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002668
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002669 usbcore.usbfs_snoop=
2670 [USB] Set to log all usbfs traffic (default 0 = off).
2671
2672 usbcore.blinkenlights=
2673 [USB] Set to cycle leds on hubs (default 0 = off).
2674
2675 usbcore.old_scheme_first=
2676 [USB] Start with the old device initialization
2677 scheme (default 0 = off).
2678
2679 usbcore.use_both_schemes=
2680 [USB] Try the other device initialization scheme
2681 if the first one fails (default 1 = enabled).
2682
2683 usbcore.initial_descriptor_timeout=
2684 [USB] Specifies timeout for the initial 64-byte
2685 USB_REQ_GET_DESCRIPTOR request in milliseconds
2686 (default 5000 = 5.0 seconds).
2687
Linus Torvalds1da177e2005-04-16 15:20:36 -07002688 usbhid.mousepoll=
2689 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002690
Alan Sternd4f373e2008-11-10 14:07:45 -05002691 usb-storage.delay_use=
2692 [UMS] The delay in seconds before a new device is
2693 scanned for Logical Units (default 5).
2694
2695 usb-storage.quirks=
2696 [UMS] A list of quirks entries to supplement or
2697 override the built-in unusual_devs list. List
2698 entries are separated by commas. Each entry has
2699 the form VID:PID:Flags where VID and PID are Vendor
2700 and Product ID values (4-digit hex numbers) and
2701 Flags is a set of characters, each corresponding
2702 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002703 a = SANE_SENSE (collect more than 18 bytes
2704 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002705 b = BAD_SENSE (don't collect more than 18
2706 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002707 c = FIX_CAPACITY (decrease the reported
2708 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002709 h = CAPACITY_HEURISTICS (decrease the
2710 reported device capacity by one
2711 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002712 i = IGNORE_DEVICE (don't bind to this
2713 device);
2714 l = NOT_LOCKABLE (don't try to lock and
2715 unlock ejectable media);
2716 m = MAX_SECTORS_64 (don't transfer more
2717 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002718 o = CAPACITY_OK (accept the capacity
2719 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002720 r = IGNORE_RESIDUE (the device reports
2721 bogus residue values);
2722 s = SINGLE_LUN (the device has only one
2723 Logical Unit);
2724 w = NO_WP_DETECT (don't test whether the
2725 medium is write-protected).
2726 Example: quirks=0419:aaf5:rl,0421:0433:rc
2727
Ian Campbell14315592010-02-17 10:38:10 +00002728 userpte=
2729 [X86] Flags controlling user PTE allocations.
2730
2731 nohigh = do not allocate PTE pages in
2732 HIGHMEM regardless of setting
2733 of CONFIG_HIGHPTE.
2734
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302735 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002736 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002737 vdso=1: enable VDSO (default)
2738 vdso=0: disable VDSO mapping
2739
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302740 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002741 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2742 vdso32=1: enable 32-bit VDSO (default)
2743 vdso32=0: disable 32-bit VDSO mapping
2744
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002745 vector= [IA-64,SMP]
2746 vector=percpu: enable percpu vector domain
2747
Linus Torvalds1da177e2005-04-16 15:20:36 -07002748 video= [FB] Frame buffer configuration
2749 See Documentation/fb/modedb.txt.
2750
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002751 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002752 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002753 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002754 Use vga=ask for menu.
2755 This is actually a boot loader parameter; the value is
2756 passed to the kernel using a special protocol.
2757
Randy Dunlapa9913042005-10-23 12:57:11 -07002758 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002759 size of <nn>. This can be used to increase the
2760 minimum size (128MB on x86). It can also be used to
2761 decrease the size and leave more room for directly
2762 mapped kernel RAM.
2763
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002764 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2765 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002766
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002767 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2768 Format: <command>
2769
2770 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2771 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002772
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002773 vt.cur_default= [VT] Default cursor shape.
2774 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2775 the parameters of the <Esc>[?A;B;Cc escape sequence;
2776 see VGA-softcursor.txt. Default: 2 = underline.
2777
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002778 vt.default_blu= [VT]
2779 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2780 Change the default blue palette of the console.
2781 This is a 16-member array composed of values
2782 ranging from 0-255.
2783
2784 vt.default_grn= [VT]
2785 Format: <green0>,<green1>,<green2>,...,<green15>
2786 Change the default green palette of the console.
2787 This is a 16-member array composed of values
2788 ranging from 0-255.
2789
2790 vt.default_red= [VT]
2791 Format: <red0>,<red1>,<red2>,...,<red15>
2792 Change the default red palette of the console.
2793 This is a 16-member array composed of values
2794 ranging from 0-255.
2795
2796 vt.default_utf8=
2797 [VT]
2798 Format=<0|1>
2799 Set system-wide default UTF-8 mode for all tty's.
2800 Default is 1, i.e. UTF-8 mode is enabled for all
2801 newly opened terminals.
2802
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002803 vt.global_cursor_default=
2804 [VT]
2805 Format=<-1|0|1>
2806 Set system-wide default for whether a cursor
2807 is shown on new VTs. Default is -1,
2808 i.e. cursors will be created by default unless
2809 overridden by individual drivers. 0 will hide
2810 cursors, 1 will display them.
2811
Linus Torvalds1da177e2005-04-16 15:20:36 -07002812 waveartist= [HW,OSS]
2813 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002814
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815 wd33c93= [HW,SCSI]
2816 See header of drivers/scsi/wd33c93.c.
2817
2818 wd7000= [HW,SCSI]
2819 See header of drivers/scsi/wd7000.c.
2820
2821 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002822 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002824 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2825 default x2apic cluster mode on platforms
2826 supporting x2apic.
2827
Jacob Panbb24c472009-09-02 07:37:17 -07002828 x86_mrst_timer= [X86-32,APBT]
2829 Choose timer option for x86 Moorestown MID platform.
2830 Two valid options are apbt timer only and lapic timer
2831 plus one apbt timer for broadcast timer.
2832 x86_mrst_timer=apbt_only | lapic_and_apbt
2833
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2835 xd_geo= See header of drivers/block/xd.c.
2836
2837 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002838 Format:
2839 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002840
Randy Dunlapa9913042005-10-23 12:57:11 -07002841______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842
2843TODO:
2844
2845 Add documentation for ALSA options.
2846 Add more DRM drivers.