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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
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
Alex Chiang0406ad32010-01-20 00:06:30 -0700203 acpi_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
204 early. Needed on some platforms to properly
205 initialize the EC.
206
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
209 default in APIC mode
210
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
213 default in PIC mode
214
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
217
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
219 use by PCI
220 Format: <irq>,<irq>...
221
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
226
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
231
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530232 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
236
Randy Dunlap4af94f32009-04-17 18:30:28 -0700237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
239
240 acpi_serialize [HW,ACPI] force serialization of AML methods
241
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
245
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800248 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700249 See Documentation/power/video.txt for information on
250 s3_bios and s3_mode.
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 s4_nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700264
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
268
Luca Tettamanti7e905602009-03-30 00:01:27 +0200269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
284
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 ad1848= [HW,OSS]
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
287
Randy Dunlap4af94f32009-04-17 18:30:28 -0700288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 advansys= [HW,SCSI]
292 See header of drivers/scsi/advansys.c.
293
294 advwdt= [HW,WDT] Advantech WDT
295 Format: <iostart>,<iostop>
296
297 aedsp16= [HW,OSS] Audio Excel DSP 16
298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
299 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700300
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700301 agp= [AGP]
302 { off | try_unsupported }
303 off: disable AGP support
304 try_unsupported: try to drive unsupported chipsets
305 (may crash computer or cause data corruption)
306
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 aha152x= [HW,SCSI]
308 See Documentation/scsi/aha152x.txt.
309
310 aha1542= [HW,SCSI]
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
312
313 aic7xxx= [HW,SCSI]
314 See Documentation/scsi/aic7xxx.txt.
315
316 aic79xx= [HW,SCSI]
317 See Documentation/scsi/aic79xx.txt.
318
Russell Kingd944d542010-02-20 16:13:29 +0000319 alignment= [KNL,ARM]
320 Allow the default userspace alignment fault handler
321 behaviour to be specified. Bit 0 enables warnings,
322 bit 1 enables fixups, and bit 2 sends a segfault.
323
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200324 amd_iommu= [HW,X86-84]
325 Pass parameters to the AMD IOMMU driver in the system.
326 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200327 isolate - enable device isolation (each device, as far
328 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100329 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100330 share - put every device behind one IOMMU into the
331 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900332 fullflush - enable flushing of IO/TLB entries when
333 they are unmapped. Otherwise they are
334 flushed before they will be reused, which
335 is a lot of faster
336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
339 Format: <a>,<b>
340 See also Documentation/kernel/input/joystick.txt
341
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
346
Randy Dunlapa9913042005-10-23 12:57:11 -0700347 apc= [HW,SPARC]
348 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 Format: noidle
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
353
Randy Dunlapca1eda22009-05-06 16:02:58 -0700354 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700355 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700359
Brian Haleyb0f83b22010-02-04 13:36:50 -0800360 autoconf= [IPV6]
361 See Documentation/networking/ipv6.txt.
362
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400363 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
364 Limit apic dumping. The parameter defines the maximal
365 number of local apics being dumped. Also it is possible
366 to set it to "all" by meaning -- no limit here.
367 Format: { 1 (default) | 2 | ... | all }.
368 The parameter valid if only apic=debug or
369 apic=verbose is specified.
370 Example: apic=debug show_lapic=all
371
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700373 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
376 Format: <io>,<irq>,<nodeID>
377
378 ataflop= [HW,M68k]
379
380 atarimouse= [HW,MOUSE] Atari Mouse
381
382 atascsi= [HW,SCSI] Atari SCSI
383
384 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
385 EzKey and similar keyboards
386
387 atkbd.reset= [HW] Reset keyboard during initialization
388
Randy Dunlapa9913042005-10-23 12:57:11 -0700389 atkbd.set= [HW] Select keyboard code set
390 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391
392 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
393 keyboards
394
395 atkbd.softraw= [HW] Choose between synthetic and real raw mode
396 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700397
398 atkbd.softrepeat= [HW]
399 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400
401 autotest [IA64]
402
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 baycom_epp= [HW,AX25]
404 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
407 Format: <io>,<mode>
408 See header of drivers/net/hamradio/baycom_par.c.
409
Randy Dunlapa9913042005-10-23 12:57:11 -0700410 baycom_ser_fdx= [HW,AX25]
411 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 Format: <io>,<irq>,<mode>[,<baud>]
413 See header of drivers/net/hamradio/baycom_ser_fdx.c.
414
Randy Dunlapa9913042005-10-23 12:57:11 -0700415 baycom_ser_hdx= [HW,AX25]
416 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 Format: <io>,<irq>,<mode>
418 See header of drivers/net/hamradio/baycom_ser_hdx.c.
419
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700420 boot_delay= Milliseconds to delay each printk during boot.
421 Values larger than 10 seconds (10000) are changed to
422 no delay (0).
423 Format: integer
424
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700425 bootmem_debug [KNL] Enable bootmem allocator debug messages.
426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700428 bttv.radio= Most important insmod options are available as
429 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
431 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
432
433 BusLogic= [HW,SCSI]
434 See drivers/scsi/BusLogic.c, comment before function
435 BusLogic_ParseDriverOptions().
436
437 c101= [NET] Moxa C101 synchronous serial card
438
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700439 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 Sometimes CPU hardware bugs make them report the cache
441 size incorrectly. The kernel will attempt work arounds
442 to fix known problems, but for some CPUs it is not
443 possible to determine what the correct size should be.
444 This option provides an override for these situations.
445
James Morris20510f22007-10-16 23:31:32 -0700446 capability.disable=
447 [SECURITY] Disable capabilities. This would normally
448 be used only if an alternative security model is to be
449 configured. Potentially dangerous and should only be
450 used if you are entirely sure of the consequences.
451
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100452 ccw_timeout_log [S390]
453 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454
Paul Menage8bab8dd2008-04-04 14:29:57 -0700455 cgroup_disable= [KNL] Disable a particular controller
456 Format: {name of the controller(s) to disable}
457 {Currently supported controllers - "memory"}
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 checkreqprot [SELINUX] Set initial checkreqprot flag value.
460 Format: { "0" | "1" }
461 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700462 0 -- check protection applied by kernel (includes
463 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 1 -- check protection requested by application.
465 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700466 Value can be changed at runtime via
467 /selinux/checkreqprot.
468
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100469 cio_ignore= [S390]
470 See Documentation/s390/CommonIO for details.
471
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700472 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700473 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200474 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700475 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200476 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 Format: { pit | tsc | cyclone | pmtmr }
478
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700479 clocksource= [GENERIC_TIME] Override the default clocksource
480 Format: <string>
481 Override the default clocksource and use the clocksource
482 with the name specified.
483 Some clocksource names to choose from, depending on
484 the platform:
485 [all] jiffies (this is the base, fallback clocksource)
486 [ACPI] acpi_pm
487 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
488 pxa_timer,timer3,32k_counter,timer0_1
489 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700490 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700491 scx200_hrt on Geode; cyclone on IBM x440
492 [MIPS] MIPS
493 [PARISC] cr16
494 [S390] tod
495 [SH] SuperH
496 [SPARC64] tick
497 [X86-64] hpet,tsc
498
Andi Kleenac72e782008-01-30 13:33:21 +0100499 clearcpuid=BITNUM [X86]
500 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800501 arch/x86/include/asm/cpufeature.h for the valid bit
502 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100503 stable over kernel options, but the vendor specific
504 ones should be.
505 Also note that user programs calling CPUID directly
506 or using the feature without checking anything
507 will still see it. This just prevents it from
508 being used by the kernel or shown in /proc/cpuinfo.
509 Also note the kernel might malfunction if you disable
510 some critical bits.
511
Robert Jennings14f966e2009-04-15 05:55:32 +0000512 cmo_free_hint= [PPC] Format: { yes | no }
513 Specify whether pages are marked as being inactive
514 when they are freed. This is used in CMO environments
515 to determine OS memory pressure for page stealing by
516 a hypervisor.
517 Default: yes
518
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530519 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100520 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100521 Range: 0 - 8192
522 Default: 64
523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700525 Format:
526 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
528 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
529 Format: <io>[,<irq>]
530
Randy Dunlapa9913042005-10-23 12:57:11 -0700531 com90xx= [HW,NET]
532 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 Format: <io>[,<irq>[,<memstart>]]
534
535 condev= [HW,S390] console device
536 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700537
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 console= [KNL] Output console device and options.
539
540 tty<n> Use the virtual console device <n>.
541
542 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800543 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800545 the form "bbbbpnf", where "bbbb" is the baud rate,
546 "p" is parity ("n", "o", or "e"), "n" is number of
547 bits, and "f" is flow control ("r" for RTS or
548 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800550 See Documentation/serial-console.txt for more
551 information. See
552 Documentation/networking/netconsole.txt for an
553 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700555 uart[8250],io,<addr>[,options]
556 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 Start an early, polled-mode console on the 8250/16550
558 UART at the specified I/O port or MMIO address,
559 switching to the matching ttyS device later. The
560 options are the same as for ttyS, above.
561
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700562 If the device connected to the port is not a TTY but a braille
563 device, prepend "brl," before the device type, for instance
564 console=brl,ttyS0
565 For now, only VisioBraille is supported.
566
Daniel Mackf324edc2009-06-16 15:33:52 -0700567 consoleblank= [KNL] The console blank (screen saver) timeout in
568 seconds. Defaults to 10*60 = 10mins. A value of 0
569 disables the blank timer.
570
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800571 coredump_filter=
572 [KNL] Change the default value for
573 /proc/<pid>/coredump_filter.
574 See also Documentation/filesystems/proc.txt.
575
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700577 Format:
578 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700580 crashkernel=nn[KMG]@ss[KMG]
581 [KNL] Reserve a chunk of physical memory to
582 hold a kernel to switch to with kexec on panic.
583
Bernhard Wallefb391592007-10-18 23:41:02 -0700584 crashkernel=range1:size1[,range2:size2,...][@offset]
585 [KNL] Same as above, but depends on the memory
586 in the running system. The syntax of range is
587 start-[end] where start and end are both
588 a memory unit (amount[KMG]). See also
589 Documentation/kdump/kdump.txt for a example.
590
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 cs89x0_dma= [HW,NET]
592 Format: <dma>
593
594 cs89x0_media= [HW,NET]
595 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700596
Randy Dunlapa9913042005-10-23 12:57:11 -0700597 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 See header of drivers/s390/block/dasd_devmap.c.
599
600 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
601 (one device per port)
602 Format: <port#>,<type>
603 See also Documentation/input/joystick-parport.txt
604
605 debug [KNL] Enable kernel debugging (events log level).
606
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700607 debug_locks_verbose=
608 [KNL] verbose self-tests
609 Format=<0|1>
610 Print debugging info while doing the locking API
611 self-tests.
612 We default to 0 (no extra messages), setting it to
613 1 will print _a lot_ more information - normally
614 only useful to kernel developers.
615
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700616 debug_objects [KNL] Enable object debugging
617
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500618 no_debug_objects
619 [KNL] Disable object debugging
620
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200621 debugpat [X86] Enable PAT debugging
622
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200623 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 Format: <area>[,<node>]
625 See also Documentation/networking/decnet.txt.
626
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700627 default_hugepagesz=
628 [same as hugepagesz=] The size of the default
629 HugeTLB page size. This is the size represented by
630 the legacy /proc/ hugepages APIs, used for SHM, and
631 default size when mounting hugetlbfs filesystems.
632 Defaults to the default architecture's huge page size
633 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700634
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 dhash_entries= [KNL]
636 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700637
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 digi= [HW,SERIAL]
639 IO parameters + enable/disable command.
640
641 digiepca= [HW,SERIAL]
642 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000643 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644
Brian Haleyb0f83b22010-02-04 13:36:50 -0800645 disable= [IPV6]
646 See Documentation/networking/ipv6.txt.
647
648 disable_ipv6= [IPV6]
649 See Documentation/networking/ipv6.txt.
650
Yinghai Lu95ffa242008-04-29 03:52:33 -0700651 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700652 The kernel tries to adjust MTRR layout from continuous
653 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700655
Yinghai Lu093af8d2008-01-30 13:33:32 +0100656 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100657 By default the kernel will trim any uncacheable
658 memory out of your available memory pool based on
659 MTRR settings. This parameter disables that behavior,
660 possibly causing your machine to run very slowly.
661
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530662 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700663 Disable PIN 1 of APIC timer
664 Can be useful to work around chipset bugs.
665
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 dmasound= [HW,OSS] Sound subsystem buffers
667
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700668 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
669 this option disables the debugging code at boot.
670
671 dma_debug_entries=<number>
672 This option allows to tune the number of preallocated
673 entries for DMA-API debugging code. One entry is
674 required per DMA-API allocation. Use this if the
675 DMA-API debugging code disables itself because the
676 architectural default is too low.
677
Joerg Roedel1745de52009-05-22 21:49:51 +0200678 dma_debug_driver=<driver_name>
679 With this option the DMA-API debugging driver
680 filter feature can be enabled at boot time. Just
681 pass the driver to filter for as the parameter.
682 The filter can be disabled or changed to another
683 driver later using sysfs.
684
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 dscc4.setup= [NET]
686
687 dtc3181e= [HW,SCSI]
688
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700689 dynamic_printk Enables pr_debug()/dev_dbg() calls if
690 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
691 These can also be switched on/off via
692 <debugfs>/dynamic_printk/modules
693
694 earlycon= [KNL] Output early console device and options.
695 uart[8250],io,<addr>[,options]
696 uart[8250],mmio,<addr>[,options]
697 Start an early, polled-mode console on the 8250/16550
698 UART at the specified I/O port or MMIO address.
699 The options are the same as for ttyS, above.
700
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530701 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 earlyprintk=vga
703 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500704 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500705 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
Randy Dunlapa9913042005-10-23 12:57:11 -0700707 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 takes over.
709
Yinghai Lu5c059172008-07-24 17:29:40 -0700710 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
712 Currently only ttyS0 and ttyS1 are supported.
713
714 Interaction with the standard serial driver is not
715 very good.
716
717 The VGA output is eventually overwritten by the real
718 console.
719
720 eata= [HW,SCSI]
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700723 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 eisa_irq_edge= [PARISC,HW]
726 See header of drivers/parisc/eisa.c.
727
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700728 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700730 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800733 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700734 See Documentation/block/as-iosched.txt and
735 Documentation/block/deadline-iosched.txt for details.
736
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530737 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700738 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800739 image elf header. Generally kexec loader will
740 pass this option to capture kernel.
741 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700743 enable_mtrr_cleanup [X86]
744 The kernel tries to adjust MTRR layout from continuous
745 to discrete, to make X server driver able to add WB
746 entry later. This parameter enables that.
747
Randy Dunlapca1eda22009-05-06 16:02:58 -0700748 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700749 Enable PIN 1 of APIC timer
750 Can be useful to work around chipset bugs
751 (in particular on some ATI chipsets).
752 The kernel tries to set a reasonable default.
753
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 enforcing [SELINUX] Set initial enforcing status.
755 Format: {"0" | "1"}
756 See security/selinux/Kconfig help text.
757 0 -- permissive (log only, no denials).
758 1 -- enforcing (deny and log).
759 Default value is 0.
760 Value can be changed at runtime via /selinux/enforce.
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 ether= [HW,NET] Ethernet cards parameters
763 This option is obsoleted by the "netdev=" option, which
764 has equivalent usage. See its documentation for details.
765
766 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
767 Format: <io>[,<irq>]
768
Akinobu Mitade1ba092006-12-08 02:39:42 -0800769 failslab=
770 fail_page_alloc=
771 fail_make_request=[KNL]
772 General fault injection mechanism.
773 Format: <interval>,<probability>,<space>,<times>
774 See also /Documentation/fault-injection/.
775
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 fd_mcs= [HW,SCSI]
777 See header of drivers/scsi/fd_mcs.c.
778
779 fdomain= [HW,SCSI]
780 See header of drivers/scsi/fdomain.c.
781
782 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000783 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
Alex Chiangf13ae302008-05-08 14:03:23 -0600785 force_pal_cache_flush
786 [IA-64] Avoid check_sal_cache_flush which may hang on
787 buggy SAL_CACHE_FLUSH implementations. Using this
788 parameter will force ia64_sal_cache_flush to call
789 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
790
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100791 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400792 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100793 as early as possible in order to facilitate early
794 boot debugging.
795
796 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400797 [FTRACE] will dump the trace buffers on oops.
798
799 ftrace_filter=[function-list]
800 [FTRACE] Limit the functions traced by the function
801 tracer at boot up. function-list is a comma separated
802 list of functions. This list can be changed at run
803 time by the set_ftrace_filter file in the debugfs
804 tracing directory.
805
806 ftrace_notrace=[function-list]
807 [FTRACE] Do not trace the functions specified in
808 function-list. This list can be changed at run time
809 by the set_ftrace_notrace file in the debugfs
810 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100811
Stefan Assmann369bc182009-10-12 22:17:21 +0200812 ftrace_graph_filter=[function-list]
813 [FTRACE] Limit the top level callers functions traced
814 by the function graph tracer at boot up.
815 function-list is a comma separated list of functions
816 that can be changed at run time by the
817 set_graph_function file in the debugfs tracing directory.
818
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 gamecon.map[2|3]=
820 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
821 support via parallel port (up to 5 devices per port)
822 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
823 See also Documentation/input/joystick-parport.txt
824
825 gamma= [HW,DRM]
826
Yinghai Luaaf23042008-01-30 13:33:09 +0100827 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
828 Format: off | on
829 default: on
830
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700831 gcov_persist= [GCOV] When non-zero (default), profiling data for
832 kernel modules is saved and remains accessible via
833 debugfs, even when the module is unloaded/reloaded.
834 When zero, profiling data is discarded and associated
835 debugfs files are removed at module unload time.
836
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 gdth= [HW,SCSI]
838 See header of drivers/scsi/gdth.c.
839
840 gpt [EFI] Forces disk with valid GPT signature but
841 invalid Protective MBR to be treated as GPT.
842
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 gvp11= [HW,SCSI]
844
845 hashdist= [KNL,NUMA] Large hashes allocated during boot
846 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700847 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700848 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849
850 hcl= [IA-64] SGI's Hardware Graph compatibility layer
851
852 hd= [EIDE] (E)IDE hard drive subsystem geometry
853 Format: <cyl>,<head>,<sect>
854
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
856 size of <nn>. This works even on boxes that have no
857 highmem otherwise. This also works to reduce highmem
858 size on bigger boxes.
859
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800860 highres= [KNL] Enable/disable high resolution timer mode.
861 Valid parameters: "on", "off"
862 Default: "on"
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 hisax= [HW,ISDN]
865 See Documentation/isdn/README.HiSax.
866
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700867 hlt [BUGS=ARM,SH]
868
869 hpet= [X86-32,HPET] option to control HPET usage
870 Format: { enable (default) | disable | force |
871 verbose }
872 disable: disable HPET and use PIT instead
873 force: allow force enabled of undocumented chips (ICH4,
874 VIA, nVidia)
875 verbose: show contents of HPET registers during setup
876
Andi Kleenb4718e62008-07-23 21:27:51 -0700877 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
878 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700879 On x86-64 and powerpc, this option can be specified
880 multiple times interleaved with hugepages= to reserve
881 huge pages of different sizes. Valid pages sizes on
882 x86-64 are 2M (when the CPU supports "pse") and 1G
883 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700884 Note that 1GB pages can only be allocated at boot time
885 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900886
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100887 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
888 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100889 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
890 If specified, z/VM IUCV HVC accepts connections
891 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100892
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700893 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700894 or register an additional I2C bus that is not
895 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700896 Format:
897 <bus_id>,<clkrate>
898
Jiri Kosina36d95732008-10-06 02:51:09 -0400899 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200901 i8042.dumbkbd [HW] Pretend that controller can only read data from
902 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 (Don't attempt to blink the leds)
904 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500905 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400906 i8042.noloop [HW] Disable the AUX Loopback command while probing
907 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 i8042.nomux [HW] Don't check presence of an active multiplexing
909 controller
910 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
911 controllers
912 i8042.panicblink=
913 [HW] Frequency with which keyboard LEDs should blink
914 when kernel panics (default is 0.5 sec)
915 i8042.reset [HW] Reset the controller during init and cleanup
916 i8042.unlock [HW] Unlock (ignore) the keylock
917
918 i810= [HW,DRM]
919
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700920 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
921 indicates that the driver is running on unsupported
922 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
924 does not match list of supported models.
925 i8k.power_status
926 [HW] Report power status in /proc/i8k
927 (disabled by default)
928 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
929 capability is set.
930
931 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
932 See Documentation/mca.txt.
933
934 icn= [HW,ISDN]
935 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
936
David Fries0af80c02009-02-25 20:28:21 +0100937 ide-core.nodma= [HW] (E)IDE subsystem
938 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200939 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
940 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100941 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700943 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
944 Claim all unknown PCI IDE storage controllers.
945
Andi Kleenf039b752007-05-02 19:27:12 +0200946 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800947 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
948 Poll forces a polling idle loop that can slightly
949 improve the performance of waking up a idle CPU, but
950 will use a lot of power and make the system run hot.
951 Not recommended.
952 idle=mwait: On systems which support MONITOR/MWAIT but
953 the kernel chose to not use it because it doesn't save
954 as much power as a normal idle loop, use the
955 MONITOR/MWAIT idle loop anyways. Performance should be
956 the same as idle=poll.
957 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800958 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800959 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700960
Ingo Molnar792908222006-12-06 20:40:51 -0800961 ignore_loglevel [KNL]
962 Ignore loglevel setting - this will print /all/
963 kernel messages to the console. Useful for debugging.
964
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 ihash_entries= [KNL]
966 Set number of hash buckets for inode cache.
967
Mimi Zohar3323eec92009-02-04 09:06:58 -0500968 ima_audit= [IMA]
969 Format: { "0" | "1" }
970 0 -- integrity auditing messages. (Default)
971 1 -- enable informational integrity auditing messages.
972
973 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700974 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500975 default: "sha1"
976
Eric Paris5789ba32009-05-21 15:47:06 -0400977 ima_tcb [IMA]
978 Load a policy which meets the needs of the Trusted
979 Computing Base. This means IMA will measure all
980 programs exec'd, files mmap'd for exec, and all files
981 opened for read by uid=0.
982
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 in2000= [HW,SCSI]
984 See header of drivers/scsi/in2000.c.
985
986 init= [KNL]
987 Format: <full_path>
988 Run specified binary instead of /sbin/init as init
989 process.
990
991 initcall_debug [KNL] Trace initcalls as they are executed. Useful
992 for working out where the kernel is dying during
993 startup.
994
995 initrd= [BOOT] Specify the location of the initial ramdisk
996
997 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
998 Format: <irq>
999
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001000 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001001 on
1002 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001003 off
1004 Disable intel iommu driver.
1005 igfx_off [Default Off]
1006 By default, gfx is mapped as normal device. If a gfx
1007 device has a dedicated DMAR unit, the DMAR unit is
1008 bypassed by not enabling DMAR with this option. In
1009 this case, gfx device will use physical address for
1010 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001011 forcedac [x86_64]
1012 With this option iommu will not optimize to look
1013 for io virtual address below 32 bit forcing dual
1014 address cycle on pci bus for cards supporting greater
1015 than 32 bit addressing. The default is to look
1016 for translation below 32 bit and if not available
1017 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001018 strict [Default Off]
1019 With this option on every unmap_single operation will
1020 result in a hardware IOTLB flush operation as opposed
1021 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001022
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001023 inttest= [IA64]
1024
1025 iomem= Disable strict checking of access to MMIO memory
1026 strict regions from userspace.
1027 relaxed
1028
1029 iommu= [x86]
1030 off
1031 force
1032 noforce
1033 biomerge
1034 panic
1035 nopanic
1036 merge
1037 nomerge
1038 forcesac
1039 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001040 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001041
1042 io7= [HW] IO7 for Marvel based alpha systems
1043 See comment before marvel_specify_io7 in
1044 arch/alpha/kernel/core_marvel.c.
1045
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301046 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001047 0x80
1048 Standard port 0x80 based delay
1049 0xed
1050 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001051 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001052 Simple two microseconds delay
1053 none
1054 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001055
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001057 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058
1059 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001060 See comment before ip2_setup() in
1061 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
1063 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1064 See header of drivers/scsi/ips.c.
1065
Alan Cox200803d2005-06-28 20:45:18 -07001066 irqfixup [HW]
1067 When an interrupt is not handled search all handlers
1068 for it. Intended to get systems with badly broken
1069 firmware running.
1070
1071 irqpoll [HW]
1072 When an interrupt is not handled search all handlers
1073 for it. Also check all handlers each timer
1074 interrupt. Intended to get systems with badly broken
1075 firmware running.
1076
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001078 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079
1080 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001081 Format:
1082 <cpu number>,...,<cpu number>
1083 or
Li Zefanb225d442008-11-06 12:53:39 -08001084 <cpu number>-<cpu number>
1085 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001086 or a mixture
1087 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001088
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 This option can be used to specify one or more CPUs
1090 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001091 algorithms. You can move a process onto or off an
1092 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093 <cpu number> begins at 0 and the maximum value is
1094 "number of CPUs in system - 1".
1095
1096 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001097 alternative -- manually setting the CPU mask of all
1098 tasks in the system -- can cause problems and
1099 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
Randy Dunlapa9913042005-10-23 12:57:11 -07001101 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102
1103 js= [HW,JOY] Analog joystick
1104 See Documentation/input/joystick.txt.
1105
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001106 keepinitrd [HW,ARM]
1107
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301108 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001109 specifies the amount of memory usable by the kernel
1110 for non-movable allocations. The requested amount is
1111 spread evenly throughout all nodes in the system. The
1112 remaining memory in each node is used for Movable
1113 pages. In the event, a node is too small to have both
1114 kernelcore and Movable pages, kernelcore pages will
1115 take priority and other nodes will have a larger number
1116 of kernelcore pages. The Movable zone is used for the
1117 allocation of pages that may be reclaimed or moved
1118 by the page migration subsystem. This means that
1119 HugeTLB pages may not be allocated from this zone.
1120 Note that allocations like PTEs-from-HighMem still
1121 use the HighMem zone if it exists, and the Normal
1122 zone if it does not.
1123
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001124 kgdboc= [HW] kgdb over consoles.
1125 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001126 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001127 Format: <serial_device>[,baud]
1128
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001129 kmac= [MIPS] korina ethernet MAC address.
1130 Configure the RouterBoard 532 series on-chip
1131 Ethernet adapter MAC address.
1132
Catalin Marinas04f70332009-06-11 13:22:39 +01001133 kmemleak= [KNL] Boot-time kmemleak enable/disable
1134 Valid arguments: on, off
1135 Default: on
1136
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301137 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001138 in oops dumps.
1139
Andre Przywarafef07aa2009-07-10 14:20:35 +02001140 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1141 Default is 0 (don't ignore, but inject #GP)
1142
1143 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1144 Default is 1 (enabled)
1145
1146 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1147 Default is 0 (off)
1148
1149 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1150 for all guests.
1151 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1152
1153 kvm-intel.bypass_guest_pf=
1154 [KVM,Intel] Disables bypassing of guest page faults
1155 on Intel chips. Default is 1 (enabled)
1156
1157 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1158 (virtualized MMU) support on capable Intel chips.
1159 Default is 1 (enabled)
1160
1161 kvm-intel.emulate_invalid_guest_state=
1162 [KVM,Intel] Enable emulation of invalid guest states
1163 Default is 0 (disabled)
1164
1165 kvm-intel.flexpriority=
1166 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1167 Default is 1 (enabled)
1168
1169 kvm-intel.unrestricted_guest=
1170 [KVM,Intel] Disable unrestricted guest feature
1171 (virtualized real and unpaged mode) on capable
1172 Intel chips. Default is 1 (enabled)
1173
1174 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1175 feature (tagged TLBs) on capable Intel chips.
1176 Default is 1 (enabled)
1177
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 l2cr= [PPC]
1179
Robert Brosea78bfbf2008-03-29 07:20:23 +11001180 l3cr= [PPC]
1181
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001182 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001183 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301185 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001186 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001187
FD Camifcb71f62008-01-06 19:08:56 +01001188 libata.dma= [LIBATA] DMA control
1189 libata.dma=0 Disable all PATA and SATA DMA
1190 libata.dma=1 PATA and SATA Disk DMA only
1191 libata.dma=2 ATAPI (CDROM) DMA only
1192 libata.dma=4 Compact Flash DMA only
1193 Combinations also work, so libata.dma=3 enables DMA
1194 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001195
1196 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1197 libata.ignore_hpa=0 keep BIOS limits (default)
1198 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001199
Dave Jones78e70c22007-09-27 11:50:13 -04001200 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1201 when set.
1202 Format: <int>
1203
Tejun Heo33267322008-02-13 09:15:09 +09001204 libata.force= [LIBATA] Force configurations. The format is comma
1205 separated list of "[ID:]VAL" where ID is
1206 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1207 matching port, link or device. Basically, it matches
1208 the ATA ID string printed on console by libata. If
1209 the whole ID part is omitted, the last PORT and DEVICE
1210 values are used. If ID hasn't been specified yet, the
1211 configuration applies to all ports, links and devices.
1212
1213 If only DEVICE is omitted, the parameter applies to
1214 the port and all links and devices behind it. DEVICE
1215 number of 0 either selects the first device or the
1216 first fan-out link behind PMP device. It does not
1217 select the host link. DEVICE number of 15 selects the
1218 host link and device attached to it.
1219
1220 The VAL specifies the configuration to force. As long
1221 as there's no ambiguity shortcut notation is allowed.
1222 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1223 The following configurations can be forced.
1224
1225 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1226 Any ID with matching PORT is used.
1227
1228 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1229
1230 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1231 udma[/][16,25,33,44,66,100,133] notation is also
1232 allowed.
1233
1234 * [no]ncq: Turn on or off NCQ.
1235
Tejun Heo05944bd2008-08-13 20:19:09 +09001236 * nohrst, nosrst, norst: suppress hard, soft
1237 and both resets.
1238
Tejun Heo33267322008-02-13 09:15:09 +09001239 If there are multiple matching configurations changing
1240 the same attribute, the last one is used.
1241
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001242 lmb=debug [KNL] Enable lmb debug messages.
1243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001245 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001247 lockd.nlm_grace_period=P [NFS] Assign grace period.
1248 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001250 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1251 Format: <integer>
1252
1253 lockd.nlm_timeout=T [NFS] Assign timeout value.
1254 Format: <integer>
1255
1256 lockd.nlm_udpport=M [NFS] Assign UDP port.
1257 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258
1259 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1260 Format: <irq>
1261
1262 loglevel= All Kernel Messages with a loglevel smaller than the
1263 console loglevel will be printed to the console. It can
1264 also be changed with klogd or other programs. The
1265 loglevels are defined as follows:
1266
1267 0 (KERN_EMERG) system is unusable
1268 1 (KERN_ALERT) action must be taken immediately
1269 2 (KERN_CRIT) critical conditions
1270 3 (KERN_ERR) error conditions
1271 4 (KERN_WARNING) warning conditions
1272 5 (KERN_NOTICE) normal but significant condition
1273 6 (KERN_INFO) informational
1274 7 (KERN_DEBUG) debug-level messages
1275
1276 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001277 Format: { n | nk | nM }
1278 n must be a power of two. The default size
1279 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
Randy Dunlapaccaa242007-10-16 01:29:37 -07001281 logo.nologo [FB] Disables display of the built-in Linux logo.
1282 This may be used to provide more screen space for
1283 kernel log messages and is useful when debugging
1284 kernel boot problems.
1285
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 lp=0 [LP] Specify parallel ports to use, e.g,
1287 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1288 lp=reset first parallel port). 'lp=0' disables the
1289 lp=auto printer driver. 'lp=reset' (which can be
1290 specified in addition to the ports) causes
1291 attached printers to be reset. Using
1292 lp=port1,port2,... specifies the parallel ports
1293 to associate lp devices with, starting with
1294 lp0. A port specification may be 'none' to skip
1295 that lp device, or a parport name such as
1296 'parport0'. Specifying 'lp=auto' instead of a
1297 port specification list means that device IDs
1298 from each port should be examined, to see if
1299 an IEEE 1284-compliant printer is attached; if
1300 so, the driver will manage that printer.
1301 See also header of drivers/char/lp.c.
1302
1303 lpj=n [KNL]
1304 Sets loops_per_jiffy to given constant, thus avoiding
1305 time-consuming boot-time autodetection (up to 250 ms per
1306 CPU). 0 enables autodetection (default). To determine
1307 the correct value for your kernel, boot with normal
1308 autodetection and see what value is printed. Note that
1309 on SMP systems the preset will be applied to all CPUs,
1310 which is likely to cause problems if your CPUs need
1311 significantly divergent settings. An incorrect value
1312 will cause delays in the kernel to be wrong, leading to
1313 unpredictable I/O errors and other breakage. Although
1314 unlikely, in the extreme case this might damage your
1315 hardware.
1316
1317 ltpc= [NET]
1318 Format: <io>,<irq>,<dma>
1319
Randy Dunlapa9913042005-10-23 12:57:11 -07001320 mac5380= [HW,SCSI] Format:
1321 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322
Randy Dunlapa9913042005-10-23 12:57:11 -07001323 machvec= [IA64] Force the use of a particular machine-vector
1324 (machvec) in a generic kernel.
1325 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326
Wu Zhangjin3209e702009-07-02 23:27:12 +08001327 machtype= [Loongson] Share the same kernel image file between different
1328 yeeloong laptop.
1329 Example: machtype=lemote-yeeloong-2f-7inch
1330
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001331 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1332 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333
1334 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001335 should make use of. maxcpus=n : n >= 0 limits the
1336 kernel to using 'n' processors. n=0 is a special case,
1337 it is equivalent to "nosmp", which also disables
1338 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001340 max_loop= [LOOP] Maximum number of loopback devices that can
1341 be mounted
1342 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001343
Randy Dunlapa9913042005-10-23 12:57:11 -07001344 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 Should be between 1 and 2^32-1.
1346
1347 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001348 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 Should be between 1 and 16384.
1350
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 mcatest= [IA-64]
1352
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001353 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354
Uwe Hermann71cced62008-10-20 09:32:21 -07001355 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 md= [HW] RAID subsystems devices and level
1358 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001359
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 mdacon= [MDA]
1361 Format: <first>,<last>
1362 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001363
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1365 Amount of memory to be used when the kernel is not able
1366 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001367 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 address space collisions. Without memmap= PCI devices
1369 could be placed at addresses belonging to unused RAM.
1370
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001371 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 memory.
1373
Paul Mundt6902aa82008-09-21 17:14:42 +09001374 memchunk=nn[KMG]
1375 [KNL,SH] Allow user to override the default size for
1376 per-device physically contiguous DMA buffers.
1377
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301378 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 E820 memory map, as specified by the user.
1380 Such memmap=exactmap lines can be constructed based on
1381 BIOS output or other requirements. See the memmap=nn@ss
1382 option description.
1383
1384 memmap=nn[KMG]@ss[KMG]
1385 [KNL] Force usage of a specific region of memory
1386 Region of memory to be used, from ss to ss+nn.
1387
1388 memmap=nn[KMG]#ss[KMG]
1389 [KNL,ACPI] Mark specific memory as ACPI data.
1390 Region of memory to be used, from ss to ss+nn.
1391
1392 memmap=nn[KMG]$ss[KMG]
1393 [KNL,ACPI] Mark specific memory as reserved.
1394 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001395 Example: Exclude memory from 0x18690000-0x1869ffff
1396 memmap=64K$0x18690000
1397 or
1398 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001400 memory_corruption_check=0/1 [X86]
1401 Some BIOSes seem to corrupt the first 64k of
1402 memory when doing things like suspend/resume.
1403 Setting this option will scan the memory
1404 looking for corruption. Enabling this will
1405 both detect corruption and prevent the kernel
1406 from using the memory being corrupted.
1407 However, its intended as a diagnostic tool; if
1408 repeatable BIOS-originated corruption always
1409 affects the same memory, you can use memmap=
1410 to prevent the kernel from using that memory.
1411
1412 memory_corruption_check_size=size [X86]
1413 By default it checks for corruption in the low
1414 64k, making this memory unavailable for normal
1415 use. Use this parameter to scan for
1416 corruption in more or less memory.
1417
1418 memory_corruption_check_period=seconds [X86]
1419 By default it checks for corruption every 60
1420 seconds. Use this parameter to check at some
1421 other rate. 0 disables periodic checking.
1422
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001423 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001424 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001425 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001426 Specifies the number of memtest passes to be
1427 performed. Each pass selects another test
1428 pattern from a given set of patterns. Memtest
1429 fills the memory with this pattern, validates
1430 memory contents and reserves bad memory
1431 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 meye.*= [HW] Set MotionEye Camera parameters
1434 See Documentation/video4linux/meye.txt.
1435
Andres Salomon8f368812007-10-12 23:04:06 +02001436 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1437 Multi-Function General Purpose Timers on AMD Geode
1438 platforms.
1439
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001440 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1441 the BIOS has incorrectly applied a workaround. TinyBIOS
1442 version 0.98 is known to be affected, 0.99 fixes the
1443 problem by letting the user disable the workaround.
1444
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 mga= [HW,DRM]
1446
Randy Dunlap1c207f92008-11-19 15:36:16 -08001447 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1448 physical address is ignored.
1449
Michel Pollet39f45d72009-05-20 11:10:31 +01001450 mini2440= [ARM,HW,KNL]
1451 Format:[0..2][b][c][t]
1452 Default: "0tb"
1453 MINI2440 configuration specification:
1454 0 - The attached screen is the 3.5" TFT
1455 1 - The attached screen is the 7" TFT
1456 2 - The VGA Shield is attached (1024x768)
1457 Leaving out the screen size parameter will not load
1458 the TFT driver, and the framebuffer will be left
1459 unconfigured.
1460 b - Enable backlight. The TFT backlight pin will be
1461 linked to the kernel VESA blanking code and a GPIO
1462 LED. This parameter is not necessary when using the
1463 VGA shield.
1464 c - Enable the s3c camera interface.
1465 t - Reserved for enabling touchscreen support. The
1466 touchscreen support is not enabled in the mainstream
1467 kernel as of 2.6.30, a preliminary port can be found
1468 in the "bleeding edge" mini2440 support kernel at
1469 http://repo.or.cz/w/linux-2.6/mini2440.git
1470
Mel Gorman6b74ab92008-07-23 21:26:49 -07001471 mminit_loglevel=
1472 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1473 parameter allows control of the logging verbosity for
1474 the additional memory initialisation checks. A value
1475 of 0 disables mminit logging and a level of 4 will
1476 log everything. Information is printed at KERN_DEBUG
1477 so loglevel=8 may also need to be specified.
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 mousedev.tap_time=
1480 [MOUSE] Maximum time between finger touching and
1481 leaving touchpad surface for touch to be considered
1482 a tap and be reported as a left button click (for
1483 touchpads working in absolute mode only).
1484 Format: <msecs>
1485 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1486 reporting absolute coordinates, such as tablets
1487 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1488 reporting absolute coordinates, such as tablets
1489
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301490 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001491 is similar to kernelcore except it specifies the
1492 amount of memory used for migratable allocations.
1493 If both kernelcore and movablecore is specified,
1494 then kernelcore will be at *least* the specified
1495 value but may be more. If movablecore on its own
1496 is specified, the administrator must be careful
1497 that the amount of memory usable for all allocations
1498 is not too small.
1499
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 mpu401= [HW,OSS]
1501 Format: <io>,<irq>
1502
1503 MTD_Partition= [MTD]
1504 Format: <name>,<region-number>,<size>,<offset>
1505
Randy Dunlapa9913042005-10-23 12:57:11 -07001506 MTD_Region= [MTD] Format:
1507 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508
1509 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001510 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001512 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1513
1514 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1515
1516 boundary - index of last SLC block on Flex-OneNAND.
1517 The remaining blocks are configured as MLC blocks.
1518 lock - Configure if Flex-OneNAND boundary should be locked.
1519 Once locked, the boundary cannot be changed.
1520 1 indicates lock status, 0 indicates unlock status.
1521
Ben Dooks9db829f2008-07-03 11:24:29 +01001522 mtdset= [ARM]
1523 ARM/S3C2412 JIVE boot control
1524
1525 See arch/arm/mach-s3c2412/mach-jive.c
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001528 [HW] Make the MicroTouch USB driver use raw coordinates
1529 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001531 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001532 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001533 that could hold holes aka. UC entries.
1534
1535 mtrr_gran_size=nn[KMG] [X86]
1536 Used for mtrr cleanup. It is granularity of mtrr block.
1537 Default is 1.
1538 Large value could prevent small alignment from
1539 using up MTRRs.
1540
1541 mtrr_spare_reg_nr=n [X86]
1542 Format: <integer>
1543 Range: 0,7 : spare reg number
1544 Default : 1
1545 Used for mtrr cleanup. It is spare mtrr entries number.
1546 Set to 2 or more if your graphical card needs more.
1547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1549
1550 NCR_D700= [HW,SCSI]
1551 See header of drivers/scsi/NCR_D700.c.
1552
1553 ncr5380= [HW,SCSI]
1554
1555 ncr53c400= [HW,SCSI]
1556
1557 ncr53c400a= [HW,SCSI]
1558
1559 ncr53c406a= [HW,SCSI]
1560
1561 ncr53c8xx= [HW,SCSI]
1562
1563 netdev= [NET] Network devices parameters
1564 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1565 Note that mem_start is often overloaded to mean
1566 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001567 This usage is only documented in each driver source
1568 file if at all.
1569
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001570 nf_conntrack.acct=
1571 [NETFILTER] Enable connection tracking flow accounting
1572 0 to disable accounting
1573 1 to enable accounting
1574 Default value depends on CONFIG_NF_CT_ACCT that is
1575 going to be removed in 2.6.29.
1576
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001578 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
1580 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001581 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582
Trond Myklebusta72b4422006-01-03 09:55:41 +01001583 nfs.callback_tcpport=
1584 [NFS] set the TCP port on which the NFSv4 callback
1585 channel should listen.
1586
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001587 nfs.cache_getent=
1588 [NFS] sets the pathname to the program which is used
1589 to update the NFS client cache entries.
1590
1591 nfs.cache_getent_timeout=
1592 [NFS] sets the timeout after which an attempt to
1593 update a cache entry is deemed to have failed.
1594
Trond Myklebust58df0952006-01-03 09:55:57 +01001595 nfs.idmap_cache_timeout=
1596 [NFS] set the maximum lifetime for idmapper cache
1597 entries.
1598
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001599 nfs.enable_ino64=
1600 [NFS] enable 64-bit inode numbers.
1601 If zero, the NFS client will fake up a 32-bit inode
1602 number for the readdir() and stat() syscalls instead
1603 of returning the full 64-bit number.
1604 The default is to return 64-bit inode numbers.
1605
Paul Mundt1e1030d2009-09-01 17:38:32 +09001606 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001607 when a NMI is triggered.
1608 Format: [state][,regs][,debounce][,die]
1609
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301610 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001611 Format: [panic,][num]
1612 Valid num: 0,1,2
1613 0 - turn nmi_watchdog off
1614 1 - use the IO-APIC timer for the NMI watchdog
1615 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001616 a performance counter. Note: This will use one
1617 performance counter and the local APIC's performance
1618 vector.
1619 When panic is specified, panic when an NMI watchdog
1620 timeout occurs.
1621 This is useful when you use a panic=... timeout and
1622 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001623 Instead of 1 and 2 it is possible to use the following
1624 symbolic names: lapic and ioapic
1625 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
Anton Vorontsovbff38772009-07-08 11:10:56 -07001627 netpoll.carrier_timeout=
1628 [NET] Specifies amount of time (in seconds) that
1629 netpoll should wait for a carrier. By default netpoll
1630 waits 4 seconds.
1631
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001632 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 emulation library even if a 387 maths coprocessor
1634 is present.
1635
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001636 no_console_suspend
1637 [HW] Never suspend the console
1638 Disable suspending of consoles during suspend and
1639 hibernate operations. Once disabled, debugging
1640 messages can reach various consoles while the rest
1641 of the system is being put to sleep (ie, while
1642 debugging driver suspend/resume hooks). This may
1643 not work reliably with all consoles, but is known
1644 to work with serial and VGA consoles.
1645
Christoph Lameterc1aee212007-05-31 00:40:47 -07001646 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1647 caches in the slab allocator. Saves per-node memory,
1648 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001649
Randy Dunlapa9913042005-10-23 12:57:11 -07001650 noalign [KNL,ARM]
1651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 noapic [SMP,APIC] Tells the kernel to not make use of any
1653 IOAPICs that may be present in the system.
1654
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 nobats [PPC] Do not use BATs for mapping kernel lowmem
1656 on "Classic" PPC cores.
1657
1658 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001659
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001660 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1661
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001662 nodelayacct [KNL] Disable per-task delay accounting
1663
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1665
Paul Mundt6902aa82008-09-21 17:14:42 +09001666 nodsp [SH] Disable hardware DSP at boot time.
1667
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301668 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001669
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 noexec [IA-64]
1671
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301672 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001673 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001675 noexec=off: disable non-executable mappings
1676
1677 noexec32 [X86-64]
1678 This affects only 32-bit executables.
1679 noexec32=on: enable non-executable mappings (default)
1680 read doesn't imply executable mappings
1681 noexec32=off: disable non-executable mappings
1682 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
Paul Mundt6902aa82008-09-21 17:14:42 +09001684 nofpu [SH] Disable hardware FPU at boot time.
1685
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001686 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001687 register save and restore. The kernel will only save
1688 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689
Suresh Siddha0c752a92009-05-22 12:17:45 -07001690 noxsave [BUGS=X86] Disables x86 extended register state save
1691 and restore using xsave. The kernel will fallback to
1692 enabling legacy floating-point and sse state.
1693
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001694 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1695 wfi(ARM) instruction doesn't work correctly and not to
1696 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001697
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001698 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 instruction doesn't work correctly and not to
1700 use it.
1701
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001702 no_file_caps Tells the kernel not to honor file capabilities. The
1703 only way then for a file to be executed with privilege
1704 is to be setuid root or executed by root.
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 nohalt [IA-64] Tells the kernel not to use the power saving
1707 function PAL_HALT_LIGHT when idle. This increases
1708 power-consumption. On the positive side, it reduces
1709 interrupt wake-up latency, which may improve performance
1710 in certain environments such as networked servers or
1711 real-time systems.
1712
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001713 nohz= [KNL] Boottime enable/disable dynamic ticks
1714 Valid arguments: on, off
1715 Default: on
1716
Paul Mundteeee7852009-04-02 12:31:16 +09001717 noiotrap [SH] Disables trapped I/O port accesses.
1718
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001719 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 disable unhandled interrupt sources.
1721
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301722 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001723 broken timer IRQ sources.
1724
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 noisapnp [ISAPNP] Disables ISA PnP code.
1726
1727 noinitrd [RAM] Tells the kernel not to load any configured
1728 initial RAM disk.
1729
Weidong Han03ea8152009-04-17 16:42:15 +08001730 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1731 remapping.
1732
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 nointroute [IA-64]
1734
Tony Luck0aa366f2007-07-20 11:22:30 -07001735 nojitter [IA64] Disables jitter checking for ITC timers.
1736
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001737 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001739 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 noltlbs [PPC] Do not use large page/tlb entries for kernel
1742 lowmem mapping on PPC40x.
1743
Horms312f1f02006-02-22 09:57:55 +09001744 nomca [IA-64] Disable machine check abort handling
1745
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001746 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001747
Andres Salomon83d73842007-10-12 23:04:06 +02001748 nomfgpt [X86-32] Disable Multi-Function General Purpose
1749 Timer usage (for AMD Geode machines).
1750
Jiri Kosina016ddd92010-01-18 17:05:40 +01001751 nopat [X86] Disable PAT (page attribute table extension of
1752 pagetables) support.
1753
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001754 norandmaps Don't use address space randomization. Equivalent to
1755 echo 0 > /proc/sys/kernel/randomize_va_space
1756
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001757 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001758
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001759 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001760 with UP alternatives
1761
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 noresidual [PPC] Don't use residual data on PReP machines.
1763
Randy Dunlapa9913042005-10-23 12:57:11 -07001764 noresume [SWSUSP] Disables resume and restores original swap
1765 space.
1766
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 no-scroll [VGA] Disables scrollback.
1768 This is required for the Braillex ib80-piezo Braille
1769 reader made by F.H. Papenmeier (Germany).
1770
1771 nosbagart [IA-64]
1772
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001773 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001774
Len Brown61ec7562007-08-16 03:34:22 -04001775 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1776 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777
Dave Jones97842212007-07-15 23:41:05 -07001778 nosoftlockup [KNL] Disable the soft-lockup detector.
1779
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001780 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001781 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001782
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 nosync [HW,M68K] Disables sync negotiation for all devices.
1784
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001785 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786
1787 nousb [USB] Disable the USB subsystem
1788
1789 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001790
Weidong Han2b2fd872009-04-17 16:42:12 +08001791 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1792
Fenghua Yua6c75b862008-03-14 13:57:08 -07001793 nptcg= [IA64] Override max number of concurrent global TLB
1794 purges which is reported from either PAL_VM_SUMMARY or
1795 SAL PALO.
1796
Yinghai Lu2b633e32010-02-10 01:20:37 -08001797 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1798 could support. nr_cpus=n : n >= 1 limits the kernel to
1799 supporting 'n' processors. Later in runtime you can not
1800 use hotplug cpu feature to put more cpu back to online.
1801 just like you compile the kernel NR_CPUS=n
1802
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001803 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1804
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001805 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1806 one of ['zone', 'node', 'default'] can be specified
1807 This can be set from sysctl after boot.
1808 See Documentation/sysctl/vm.txt for details.
1809
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001810 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1811 See Documentation/debugging-via-ohci1394.txt for more
1812 info.
1813
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001814 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1815 Rather than timing out after 20 ms if an EC
1816 command is not properly ACKed, override the length
1817 of the timeout. We have interrupts disabled while
1818 waiting for the ACK, so if this is set too high
1819 interrupts *may* be lost!
1820
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001821 omap_mux= [OMAP] Override bootloader pin multiplexing.
1822 Format: <mux_mode0.mode_name=value>...
1823 For example, to override I2C bus2:
1824 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1825
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 opl3= [HW,OSS]
1827 Format: <io>
1828
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829 oprofile.timer= [HW]
1830 Use timer interrupt instead of performance counters
1831
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001832 oprofile.cpu_type= Force an oprofile cpu type
1833 This might be useful if you have an older oprofile
1834 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001835 Format: { arch_perfmon }
1836 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001837 perfmon on Intel CPUs instead of the
1838 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001839
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840 osst= [HW,SCSI] SCSI Tape Driver
1841 Format: <buffer_size>,<write_threshold>
1842 See also Documentation/scsi/st.txt.
1843
1844 panic= [KNL] Kernel behaviour on panic
1845 Format: <timeout>
1846
1847 parkbd.port= [HW] Parallel port number the keyboard adapter is
1848 connected to, default is 0.
1849 Format: <parport#>
1850 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1851 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001852 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853
Randy Dunlapa9913042005-10-23 12:57:11 -07001854 parport= [HW,PPT] Specify parallel ports. 0 disables.
1855 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1856 Use 'auto' to force the driver to use any
1857 IRQ/DMA settings detected (the default is to
1858 ignore detected IRQ/DMA settings because of
1859 possible conflicts). You can specify the base
1860 address, IRQ, and DMA settings; IRQ and DMA
1861 should be numbers, or 'auto' (for using detected
1862 settings on that particular port), or 'nofifo'
1863 (to avoid using a FIFO even if it is detected).
1864 Parallel ports are assigned in the order they
1865 are specified on the command line, starting
1866 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867
Randy Dunlapa9913042005-10-23 12:57:11 -07001868 parport_init_mode= [HW,PPT]
1869 Configure VIA parallel port to operate in
1870 a specific mode. This is necessary on Pegasos
1871 computer where firmware has no options for setting
1872 up parallel port mode and sets it to spp.
1873 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 Format: [spp|ps2|epp|ecp|ecpepp]
1875
Randy Dunlapa9913042005-10-23 12:57:11 -07001876 pas2= [HW,OSS] Format:
1877 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1878
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879 pas16= [HW,SCSI]
1880 See header of drivers/scsi/pas16.c.
1881
Andrew Mortondd287792006-03-23 03:00:57 -08001882 pause_on_oops=
1883 Halt all CPUs after the first oops has been printed for
1884 the specified number of seconds. This is to be used if
1885 your oopses keep scrolling off the screen.
1886
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887 pcbit= [HW,ISDN]
1888
1889 pcd. [PARIDE]
1890 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001891 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892
Randy Dunlapa9913042005-10-23 12:57:11 -07001893 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001894 earlydump [X86] dump PCI config space before the kernel
1895 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001896 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001897 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001898 the hardware directly. Use this if your machine
1899 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001900 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001901 hardware access methods are allowed. Use this
1902 if you experience crashes upon bootup and you
1903 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001904 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001905 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001906 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001907 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001908 noaer [PCIE] If the PCIEAER kernel config parameter is
1909 enabled, this kernel boot option can be used to
1910 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001911 nodomains [PCI] Disable support for multiple PCI
1912 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301913 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001914 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001915 check_enable_amd_mmconf [X86] check for and enable
1916 properly configured MMIO access to PCI
1917 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001918 nomsi [MSI] If the PCI_MSI kernel config parameter is
1919 enabled, this kernel boot option can be used to
1920 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001921 noioapicquirk [APIC] Disable all boot interrupt quirks.
1922 Safety option to keep boot IRQs enabled. This
1923 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001924 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1925 primary IO-APIC for bridges that cannot disable
1926 boot IRQs. This fixes a source of spurious IRQs
1927 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001928 noioapicreroute [APIC] Disable workaround that uses the
1929 boot IRQ equivalent of an IRQ that connects to
1930 a chipset where boot IRQs cannot be disabled.
1931 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001932 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001933 routing table. These calls are known to be buggy
1934 on several machines and they hang the machine
1935 when used, but on other computers it's the only
1936 way to get the interrupt routing table. Try
1937 this option if the kernel is unable to allocate
1938 IRQs or discover secondary PCI buses on your
1939 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001940 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001941 Use with caution as certain devices share
1942 address decoders between ROMs and other
1943 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001944 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001945 expansion ROMs that do not already have
1946 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001947 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001948 assigned automatically to PCI devices. You can
1949 make the kernel exclude IRQs of your ISA cards
1950 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001951 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001952 of the PIRQ table (normally generated
1953 by the BIOS) if it is outside the
1954 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001955 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001956 useful if the kernel is unable to find your
1957 secondary buses and you want to tell it
1958 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001959 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001960 numbers ourselves, overriding
1961 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001962 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001963 in the BIOS $PIR table. This is needed on
1964 some systems with broken BIOSes, notably
1965 some HP Pavilion N5400 and Omnibook XE3
1966 notebooks. This will have no effect if ACPI
1967 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001968 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001969 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001970 use_crs [X86] Use PCI host bridge window information
1971 from ACPI. On BIOSes from 2008 or later, this
1972 is enabled by default. If you need to use this,
1973 please report a bug.
1974 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1975 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001976 routeirq Do IRQ routing for all PCI devices.
1977 This is normally done in pci_enable_device(),
1978 so this option is a temporary workaround
1979 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001980 skip_isa_align [X86] do not align io start addr, so can
1981 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001982 firmware [ARM] Do not re-enumerate the bus but instead
1983 just use the configuration from the
1984 bootloader. This is currently used on
1985 IXP2000 systems where the bus has to be
1986 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001987 noearly [X86] Don't do any early type 1 scanning.
1988 This might help on some broken boards which
1989 machine check when some devices' config space
1990 is read. But various workarounds are disabled
1991 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001992 bfsort Sort PCI devices into breadth-first order.
1993 This sorting is done to get a device
1994 order compatible with older (<= 2.4) kernels.
1995 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001996 cbiosize=nn[KMG] The fixed amount of bus space which is
1997 reserved for the CardBus bridge's IO window.
1998 The default value is 256 bytes.
1999 cbmemsize=nn[KMG] The fixed amount of bus space which is
2000 reserved for the CardBus bridge's memory
2001 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002002 resource_alignment=
2003 Format:
2004 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2005 Specifies alignment and device to reassign
2006 aligned memory resources.
2007 If <order of align> is not specified,
2008 PAGE_SIZE is used as alignment.
2009 PCI-PCI bridge can be specified, if resource
2010 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002011 ecrc= Enable/disable PCIe ECRC (transaction layer
2012 end-to-end CRC checking).
2013 bios: Use BIOS/firmware settings. This is the
2014 the default.
2015 off: Turn ECRC off
2016 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002017
Chuck Ebberte5665a42008-09-24 20:40:34 -04002018 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2019 Management.
2020 off Disable ASPM.
2021 force Enable ASPM even on devices that claim not to support it.
2022 WARNING: Forcing ASPM on may cause system lockups.
2023
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002024 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2025 off Do not use native PCIe PME signaling.
2026 force Use native PCIe PME signaling even if the BIOS refuses
2027 to allow the kernel to control the relevant PCIe config
2028 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002029 nomsi Do not use MSI for native PCIe PME signaling (this makes
2030 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 pcmv= [HW,PCMCIA] BadgePAD 4
2033
2034 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002035 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036
2037 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2038 boot time.
2039 Format: { 0 | 1 }
2040 See arch/parisc/kernel/pdc_chassis.c
2041
Tejun Heof58dc012009-08-14 15:00:50 +09002042 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002043 Currently supported values are "embed" and "page".
2044 Archs may support subset or none of the selections.
2045 See comments in mm/percpu.c for details on each
2046 allocator. This parameter is primarily for debugging
2047 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002050 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051
2052 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002053 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054
2055 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002056 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057
2058 plip= [PPT,NET] Parallel port network link
2059 Format: { parport<nr> | timid | 0 }
2060 See also Documentation/parport.txt.
2061
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002062 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2063 Override pmtimer IOPort with a hex value.
2064 e.g. pmtmr=0x508
2065
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002066 pnp.debug [PNP]
2067 Enable PNP debug messages. This depends on the
2068 CONFIG_PNP_DEBUG_MESSAGES option.
2069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 pnpacpi= [ACPI]
2071 { off }
2072
2073 pnpbios= [ISAPNP]
2074 { on | off | curr | res | no-curr | no-res }
2075
2076 pnp_reserve_irq=
2077 [ISAPNP] Exclude IRQs for the autoconfiguration
2078
2079 pnp_reserve_dma=
2080 [ISAPNP] Exclude DMAs for the autoconfiguration
2081
2082 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002083 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084
2085 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002086 [ISAPNP] Exclude memory regions for the
2087 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088 Ranges are in pairs (memory base and size).
2089
Randy Dunlap4af94f32009-04-17 18:30:28 -07002090 ports= [IP_VS_FTP] IPVS ftp helper module
2091 Default is 21.
2092 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2093 may be specified.
2094 Format: <port>,<port>....
2095
Ingo Molnar45807a12007-07-15 23:40:10 -07002096 print-fatal-signals=
2097 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002098
2099 If enabled, warn about various signal handling
2100 related application anomalies: too many signals,
2101 too many POSIX.1 timers, fatal signals causing a
2102 coredump - etc.
2103
2104 If you hit the warning due to signal overflow,
2105 you might want to try "ulimit -i unlimited".
2106
Ingo Molnar45807a12007-07-15 23:40:10 -07002107 default: off.
2108
Randy Dunlape84845c2007-07-15 23:40:25 -07002109 printk.time= Show timing data prefixed to each printk message line
2110 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2111
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002112 processor.max_cstate= [HW,ACPI]
2113 Limit processor to maximum C-state
2114 max_cstate=9 overrides any DMI blacklist limit.
2115
2116 processor.nocst [HW,ACPI]
2117 Ignore the _CST method to determine C-states,
2118 instead using the legacy FADT method
2119
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002121 Format: [schedule,]<number>
2122 Param: "schedule" - profile schedule points.
2123 Param: <number> - step/bucket size as a power of 2 for
2124 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002125 Param: "sleep" - profile D-state sleeping (millisecs).
2126 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002127 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2130 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002131 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132
Randy Dunlapa9913042005-10-23 12:57:11 -07002133 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2134 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2136 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002137 psmouse.resetafter= [HW,MOUSE]
2138 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 (0 = never).
2140 psmouse.resolution=
2141 [HW,MOUSE] Set desired mouse resolution, in dpi.
2142 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002143 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 0 = disabled, 1 = enabled (default).
2145
2146 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002147 Format:
2148 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149
2150 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002151 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152
Kay Sieversdc8c8582007-08-15 12:25:38 +02002153 pty.legacy_count=
2154 [KNL] Number of legacy pty's. Overwrites compiled-in
2155 default number.
2156
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002157 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002158
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 r128= [HW,DRM]
2160
2161 raid= [HW,RAID]
2162 See Documentation/md.txt.
2163
Randy Dunlapa9913042005-10-23 12:57:11 -07002164 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002165 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002166
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002168 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002170 rcupdate.blimit= [KNL,BOOT]
2171 Set maximum number of finished RCU callbacks to process
2172 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002173
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002174 rcupdate.qhimark= [KNL,BOOT]
2175 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002176 RCU callbacks over which batch limiting is disabled.
2177
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002178 rcupdate.qlowmark= [KNL,BOOT]
2179 Set threshold of queued RCU callbacks below which
2180 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002181
Olof Johanssonffdfc402005-09-06 15:17:19 -07002182 rdinit= [KNL]
2183 Format: <full_path>
2184 Run specified binary instead of /init from the ramdisk,
2185 used for early userspace startup. See initrd.
2186
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002187 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002189 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190
Paul Jackson46b6d942008-07-04 10:00:09 -07002191 relax_domain_level=
2192 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002193 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002194
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2196
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002197 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002198 Format: nn[KMG]
2199 Reserves a hole at the top of the kernel virtual
2200 address space.
2201
Vivek Goyal7e962872006-09-27 01:50:44 -07002202 reset_devices [KNL] Force drivers to reset the underlying device
2203 during initialization.
2204
Randy Dunlapa9913042005-10-23 12:57:11 -07002205 resume= [SWSUSP]
2206 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002208 resume_offset= [SWSUSP]
2209 Specify the offset from the beginning of the partition
2210 given by "resume=" at which the swap header is located,
2211 in <PAGE_SIZE> units (needed only for swap files).
2212 See Documentation/power/swsusp-and-swap-files.txt
2213
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002214 retain_initrd [RAM] Keep initrd memory after extraction
2215
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 rhash_entries= [KNL,NET]
2217 Set number of hash buckets for route cache
2218
2219 riscom8= [HW,SERIAL]
2220 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2221
2222 ro [KNL] Mount root device read-only on boot
2223
2224 root= [KNL] Root filesystem
2225
2226 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2227 mount the root filesystem
2228
2229 rootflags= [KNL] Set root filesystem mount option string
2230
2231 rootfstype= [KNL] Set root filesystem type
2232
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002233 rootwait [KNL] Wait (indefinitely) for root device to show up.
2234 Useful for devices that are detected asynchronously
2235 (e.g. USB and MMC devices).
2236
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237 rw [KNL] Mount root device read-write on boot
2238
2239 S [KNL] Run init in single mode
2240
2241 sa1100ir [NET]
2242 See drivers/net/irda/sa1100_ir.c.
2243
Linus Torvalds1da177e2005-04-16 15:20:36 -07002244 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002245
Mike Travisf6630112009-11-17 18:22:15 -06002246 sched_debug [KNL] Enables verbose scheduler debug messages.
2247
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2249 Format: <io>[,<timeout>[,<isapnp>]]
2250
2251 scsi_debug_*= [SCSI]
2252 See drivers/scsi/scsi_debug.c.
2253
2254 scsi_default_dev_flags=
2255 [SCSI] SCSI default device flags
2256 Format: <integer>
2257
2258 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2259 Format: <vendor>:<model>:<flags>
2260 (flags are integer value)
2261
Randy Dunlap6af66322007-11-14 16:52:25 -08002262 scsi_logging_level= [SCSI] a bit mask of logging levels
2263 See drivers/scsi/scsi_logging.h for bits. Also
2264 settable via sysctl at dev.scsi.logging_level
2265 (/proc/sys/dev/scsi/logging_level).
2266 There is also a nice 'scsi_logging_level' script in the
2267 S390-tools package, available for download at
2268 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002270 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2271 discovered. async scans them in kernel threads,
2272 allowing boot to proceed. none ignores them, expecting
2273 user space to do the scan.
2274
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002275 security= [SECURITY] Choose a security module to enable at boot.
2276 If this boot parameter is not specified, only the first
2277 security module asking for security registration will be
2278 loaded. An invalid security module name will be treated
2279 as if no module has been chosen.
2280
2281 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282 Format: { "0" | "1" }
2283 See security/selinux/Kconfig help text.
2284 0 -- disable.
2285 1 -- enable.
2286 Default value is set via kernel config option.
2287 If enabled at boot time, /selinux/disable can be used
2288 later to disable prior to initial policy load.
2289
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002290 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002291
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292 shapers= [NET]
2293 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002294
Yinghai Lub05f78f2008-08-22 01:32:50 -07002295 show_msr= [x86] show boot-time MSR settings
2296 Format: { <integer> }
2297 Show boot-time (BIOS-initialized) MSR settings.
2298 The parameter means the number of CPUs to show,
2299 for example 1 means boot CPU only.
2300
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 sim710= [SCSI,HW]
2302 See header of drivers/scsi/sim710.c.
2303
2304 simeth= [IA-64]
2305 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002306
Linus Torvalds1da177e2005-04-16 15:20:36 -07002307 slram= [HW,MTD]
2308
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002309 slub_debug[=options[,slabs]] [MM, SLUB]
2310 Enabling slub_debug allows one to determine the
2311 culprit if slab objects become corrupted. Enabling
2312 slub_debug can create guard zones around objects and
2313 may poison objects when not in use. Also tracks the
2314 last alloc / free. For more information see
2315 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002316
2317 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002318 Determines the maximum allowed order for slabs.
2319 A high setting may cause OOMs due to memory
2320 fragmentation. For more information see
2321 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002322
2323 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002324 The minimum number of objects per slab. SLUB will
2325 increase the slab order up to slub_max_order to
2326 generate a sufficiently large slab able to contain
2327 the number of objects indicated. The higher the number
2328 of objects the smaller the overhead of tracking slabs
2329 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002330 For more information see Documentation/vm/slub.txt.
2331
2332 slub_min_order= [MM, SLUB]
2333 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002334 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002335 For more information see Documentation/vm/slub.txt.
2336
2337 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002338 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002339 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002340 allocs to different slabs. Debug options disable
2341 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002342 For more information see Documentation/vm/slub.txt.
2343
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344 smart2= [HW]
2345 Format: <io1>[,<io2>[,...,<io8>]]
2346
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002347 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002348 attempt to substitute SMP alternatives once at boot.
2349
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002350 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2351 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2352 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2353 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2354 smsc-ircc2.ircc_irq= [HW] IRQ line
2355 smsc-ircc2.ircc_dma= [HW] DMA channel
2356 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2357 0: Toshiba Satellite 1800 (GP data pin select)
2358 1: Fast pin select (default)
2359 2: ATC IRMode
2360
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 snd-ad1816a= [HW,ALSA]
2362
2363 snd-ad1848= [HW,ALSA]
2364
2365 snd-ali5451= [HW,ALSA]
2366
2367 snd-als100= [HW,ALSA]
2368
2369 snd-als4000= [HW,ALSA]
2370
2371 snd-azt2320= [HW,ALSA]
2372
2373 snd-cmi8330= [HW,ALSA]
2374
2375 snd-cmipci= [HW,ALSA]
2376
2377 snd-cs4231= [HW,ALSA]
2378
2379 snd-cs4232= [HW,ALSA]
2380
2381 snd-cs4236= [HW,ALSA]
2382
2383 snd-cs4281= [HW,ALSA]
2384
2385 snd-cs46xx= [HW,ALSA]
2386
2387 snd-dt019x= [HW,ALSA]
2388
2389 snd-dummy= [HW,ALSA]
2390
2391 snd-emu10k1= [HW,ALSA]
2392
2393 snd-ens1370= [HW,ALSA]
2394
2395 snd-ens1371= [HW,ALSA]
2396
2397 snd-es968= [HW,ALSA]
2398
2399 snd-es1688= [HW,ALSA]
2400
2401 snd-es18xx= [HW,ALSA]
2402
2403 snd-es1938= [HW,ALSA]
2404
2405 snd-es1968= [HW,ALSA]
2406
2407 snd-fm801= [HW,ALSA]
2408
2409 snd-gusclassic= [HW,ALSA]
2410
2411 snd-gusextreme= [HW,ALSA]
2412
2413 snd-gusmax= [HW,ALSA]
2414
2415 snd-hdsp= [HW,ALSA]
2416
2417 snd-ice1712= [HW,ALSA]
2418
2419 snd-intel8x0= [HW,ALSA]
2420
2421 snd-interwave= [HW,ALSA]
2422
2423 snd-interwave-stb=
2424 [HW,ALSA]
2425
2426 snd-korg1212= [HW,ALSA]
2427
2428 snd-maestro3= [HW,ALSA]
2429
2430 snd-mpu401= [HW,ALSA]
2431
2432 snd-mtpav= [HW,ALSA]
2433
2434 snd-nm256= [HW,ALSA]
2435
2436 snd-opl3sa2= [HW,ALSA]
2437
2438 snd-opti92x-ad1848=
2439 [HW,ALSA]
2440
2441 snd-opti92x-cs4231=
2442 [HW,ALSA]
2443
2444 snd-opti93x= [HW,ALSA]
2445
2446 snd-pmac= [HW,ALSA]
2447
2448 snd-rme32= [HW,ALSA]
2449
2450 snd-rme96= [HW,ALSA]
2451
2452 snd-rme9652= [HW,ALSA]
2453
2454 snd-sb8= [HW,ALSA]
2455
2456 snd-sb16= [HW,ALSA]
2457
2458 snd-sbawe= [HW,ALSA]
2459
2460 snd-serial= [HW,ALSA]
2461
2462 snd-sgalaxy= [HW,ALSA]
2463
2464 snd-sonicvibes= [HW,ALSA]
2465
2466 snd-sun-amd7930=
2467 [HW,ALSA]
2468
2469 snd-sun-cs4231= [HW,ALSA]
2470
2471 snd-trident= [HW,ALSA]
2472
2473 snd-usb-audio= [HW,ALSA,USB]
2474
2475 snd-via82xx= [HW,ALSA]
2476
2477 snd-virmidi= [HW,ALSA]
2478
2479 snd-wavefront= [HW,ALSA]
2480
2481 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002482
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002483 softlockup_panic=
2484 [KNL] Should the soft-lockup detector generate panics.
2485
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2487 See Documentation/sonypi.txt
2488
2489 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002490 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491
2492 spia_io_base= [HW,MTD]
2493 spia_fio_base=
2494 spia_pedr=
2495 spia_peddr=
2496
2497 sscape= [HW,OSS]
2498 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002499
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2501 See Documentation/scsi/st.txt.
2502
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002503 stacktrace [FTRACE]
2504 Enabled the stack tracer on boot up.
2505
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506 sti= [PARISC,HW]
2507 Format: <num>
2508 Set the STI (builtin display/keyboard on the HP-PARISC
2509 machines) console (graphic card) which should be used
2510 as the initial boot-console.
2511 See also comment in drivers/video/console/sticore.c.
2512
2513 sti_font= [HW]
2514 See comment in drivers/video/console/sticore.c.
2515
2516 stifb= [HW]
2517 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2518
Trond Myklebustcbf11072009-08-09 15:06:19 -04002519 sunrpc.min_resvport=
2520 sunrpc.max_resvport=
2521 [NFS,SUNRPC]
2522 SunRPC servers often require that client requests
2523 originate from a privileged port (i.e. a port in the
2524 range 0 < portnr < 1024).
2525 An administrator who wishes to reserve some of these
2526 ports for other uses may adjust the range that the
2527 kernel's sunrpc client considers to be privileged
2528 using these two parameters to set the minimum and
2529 maximum port values.
2530
Greg Banks42a7fc42007-03-06 01:42:23 -08002531 sunrpc.pool_mode=
2532 [NFS]
2533 Control how the NFS server code allocates CPUs to
2534 service thread pools. Depending on how many NICs
2535 you have and where their interrupts are bound, this
2536 option will affect which CPUs will do NFS serving.
2537 Note: this parameter cannot be changed while the
2538 NFS server is running.
2539
2540 auto the server chooses an appropriate mode
2541 automatically using heuristics
2542 global a single global pool contains all CPUs
2543 percpu one pool for each CPU
2544 pernode one pool for each NUMA node (equivalent
2545 to global on non-NUMA machines)
2546
Trond Myklebustcbf11072009-08-09 15:06:19 -04002547 sunrpc.tcp_slot_table_entries=
2548 sunrpc.udp_slot_table_entries=
2549 [NFS,SUNRPC]
2550 Sets the upper limit on the number of simultaneous
2551 RPC calls that can be sent from the client to a
2552 server. Increasing these values may allow you to
2553 improve throughput, but will also increase the
2554 amount of memory reserved for use by the client.
2555
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002557
Linus Torvalds1da177e2005-04-16 15:20:36 -07002558 switches= [HW,M68k]
2559
2560 sym53c416= [HW,SCSI]
2561 See header of drivers/scsi/sym53c416.c.
2562
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002563 sysrq_always_enabled
2564 [KNL]
2565 Ignore sysrq setting - this boot parameter will
2566 neutralize any effect of /proc/sys/kernel/sysrq.
2567 Useful for debugging.
2568
Linus Torvalds1da177e2005-04-16 15:20:36 -07002569 t128= [HW,SCSI]
2570 See header of drivers/scsi/t128.c.
2571
2572 tdfx= [HW,DRM]
2573
David Brownell77437fd2008-07-23 21:28:33 -07002574 test_suspend= [SUSPEND]
2575 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2576 standby suspend) as the system sleep state to briefly
2577 enter during system startup. The system is woken from
2578 this state using a wakeup-capable RTC alarm.
2579
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580 thash_entries= [KNL,NET]
2581 Set number of hash buckets for TCP connection
2582
Len Brownf8707ec2007-08-12 00:12:54 -04002583 thermal.act= [HW,ACPI]
2584 -1: disable all active trip points in all thermal zones
2585 <degrees C>: override all lowest active trip points
2586
Len Brownc52a7412007-08-14 15:49:32 -04002587 thermal.crt= [HW,ACPI]
2588 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002589 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002590
Len Brownf5487142007-08-12 00:12:44 -04002591 thermal.nocrt= [HW,ACPI]
2592 Set to disable actions on ACPI thermal zone
2593 critical and hot trip points.
2594
Len Brown72b33ef2007-08-12 00:12:17 -04002595 thermal.off= [HW,ACPI]
2596 1: disable ACPI thermal control
2597
Len Browna70cdc52007-08-12 00:12:35 -04002598 thermal.psv= [HW,ACPI]
2599 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002600 <degrees C>: override all passive trip points to this
2601 value
Len Browna70cdc52007-08-12 00:12:35 -04002602
Len Brown730ff342007-08-12 00:12:26 -04002603 thermal.tzp= [HW,ACPI]
2604 Specify global default ACPI thermal zone polling rate
2605 <deci-seconds>: poll all this frequency
2606 0: no polling (default)
2607
Linus Torvalds1da177e2005-04-16 15:20:36 -07002608 tmscsim= [HW,SCSI]
2609 See comment before function dc390_setup() in
2610 drivers/scsi/tmscsim.c.
2611
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002612 topology= [S390]
2613 Format: {off | on}
2614 Specify if the kernel should make use of the cpu
2615 topology informations if the hardware supports these.
2616 The scheduler will make use of these informations and
2617 e.g. base its process migration decisions on it.
2618 Default is off.
2619
Linus Torvalds1da177e2005-04-16 15:20:36 -07002620 tp720= [HW,PS2]
2621
Li Zefan9d612be2009-06-24 17:33:15 +08002622 trace_buf_size=nn[KMG]
2623 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002624
Li Zefan020e5f82009-07-01 10:47:05 +08002625 trace_event=[event-list]
2626 [FTRACE] Set and start specified trace events in order
2627 to facilitate early boot debugging.
2628 See also Documentation/trace/events.txt
2629
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002631 Format:
2632 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2633
Alok Kataria395628e2008-10-24 17:22:01 -07002634 tsc= Disable clocksource-must-verify flag for TSC.
2635 Format: <string>
2636 [x86] reliable: mark tsc clocksource as reliable, this
2637 disables clocksource verification at runtime.
2638 Used to enable high-resolution timer mode on older
2639 hardware, and in virtualized environment.
2640
Randy Dunlapa9913042005-10-23 12:57:11 -07002641 turbografx.map[2|3]= [HW,JOY]
2642 TurboGraFX parallel port interface
2643 Format:
2644 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002645 See also Documentation/input/joystick-parport.txt
2646
2647 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2648 See header of drivers/scsi/u14-34f.c.
2649
2650 uart401= [HW,OSS]
2651 Format: <io>,<irq>
2652
2653 uart6850= [HW,OSS]
2654 Format: <io>,<irq>
2655
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002656 uhash_entries= [KNL,NET]
2657 Set number of hash buckets for UDP/UDP-Lite connections
2658
Alan Stern5f8364b2006-12-05 16:29:55 -05002659 uhci-hcd.ignore_oc=
2660 [USB] Ignore overcurrent events (default N).
2661 Some badly-designed motherboards generate lots of
2662 bogus events, for ports that aren't wired to
2663 anything. Set this parameter to avoid log spamming.
2664 Note that genuine overcurrent events won't be
2665 reported either.
2666
Simon Arlotte3a61b02008-07-19 23:32:54 +01002667 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302668 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002669 Set unknown_nmi_panic=1 early on boot.
2670
Alan Sternb5e795f2007-02-20 15:00:53 -05002671 usbcore.autosuspend=
2672 [USB] The autosuspend time delay (in seconds) used
2673 for newly-detected USB devices (default 2). This
2674 is the time required before an idle device will be
2675 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002676 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002677
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002678 usbcore.usbfs_snoop=
2679 [USB] Set to log all usbfs traffic (default 0 = off).
2680
2681 usbcore.blinkenlights=
2682 [USB] Set to cycle leds on hubs (default 0 = off).
2683
2684 usbcore.old_scheme_first=
2685 [USB] Start with the old device initialization
2686 scheme (default 0 = off).
2687
2688 usbcore.use_both_schemes=
2689 [USB] Try the other device initialization scheme
2690 if the first one fails (default 1 = enabled).
2691
2692 usbcore.initial_descriptor_timeout=
2693 [USB] Specifies timeout for the initial 64-byte
2694 USB_REQ_GET_DESCRIPTOR request in milliseconds
2695 (default 5000 = 5.0 seconds).
2696
Linus Torvalds1da177e2005-04-16 15:20:36 -07002697 usbhid.mousepoll=
2698 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002699
Alan Sternd4f373e2008-11-10 14:07:45 -05002700 usb-storage.delay_use=
2701 [UMS] The delay in seconds before a new device is
2702 scanned for Logical Units (default 5).
2703
2704 usb-storage.quirks=
2705 [UMS] A list of quirks entries to supplement or
2706 override the built-in unusual_devs list. List
2707 entries are separated by commas. Each entry has
2708 the form VID:PID:Flags where VID and PID are Vendor
2709 and Product ID values (4-digit hex numbers) and
2710 Flags is a set of characters, each corresponding
2711 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002712 a = SANE_SENSE (collect more than 18 bytes
2713 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002714 b = BAD_SENSE (don't collect more than 18
2715 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002716 c = FIX_CAPACITY (decrease the reported
2717 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002718 h = CAPACITY_HEURISTICS (decrease the
2719 reported device capacity by one
2720 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002721 i = IGNORE_DEVICE (don't bind to this
2722 device);
2723 l = NOT_LOCKABLE (don't try to lock and
2724 unlock ejectable media);
2725 m = MAX_SECTORS_64 (don't transfer more
2726 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002727 o = CAPACITY_OK (accept the capacity
2728 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002729 r = IGNORE_RESIDUE (the device reports
2730 bogus residue values);
2731 s = SINGLE_LUN (the device has only one
2732 Logical Unit);
2733 w = NO_WP_DETECT (don't test whether the
2734 medium is write-protected).
2735 Example: quirks=0419:aaf5:rl,0421:0433:rc
2736
Ian Campbell14315592010-02-17 10:38:10 +00002737 userpte=
2738 [X86] Flags controlling user PTE allocations.
2739
2740 nohigh = do not allocate PTE pages in
2741 HIGHMEM regardless of setting
2742 of CONFIG_HIGHPTE.
2743
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302744 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002745 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002746 vdso=1: enable VDSO (default)
2747 vdso=0: disable VDSO mapping
2748
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302749 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002750 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2751 vdso32=1: enable 32-bit VDSO (default)
2752 vdso32=0: disable 32-bit VDSO mapping
2753
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002754 vector= [IA-64,SMP]
2755 vector=percpu: enable percpu vector domain
2756
Linus Torvalds1da177e2005-04-16 15:20:36 -07002757 video= [FB] Frame buffer configuration
2758 See Documentation/fb/modedb.txt.
2759
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002760 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002761 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002762 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763 Use vga=ask for menu.
2764 This is actually a boot loader parameter; the value is
2765 passed to the kernel using a special protocol.
2766
Randy Dunlapa9913042005-10-23 12:57:11 -07002767 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002768 size of <nn>. This can be used to increase the
2769 minimum size (128MB on x86). It can also be used to
2770 decrease the size and leave more room for directly
2771 mapped kernel RAM.
2772
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002773 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2774 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002776 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2777 Format: <command>
2778
2779 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2780 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002781
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002782 vt.cur_default= [VT] Default cursor shape.
2783 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2784 the parameters of the <Esc>[?A;B;Cc escape sequence;
2785 see VGA-softcursor.txt. Default: 2 = underline.
2786
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002787 vt.default_blu= [VT]
2788 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2789 Change the default blue palette of the console.
2790 This is a 16-member array composed of values
2791 ranging from 0-255.
2792
2793 vt.default_grn= [VT]
2794 Format: <green0>,<green1>,<green2>,...,<green15>
2795 Change the default green palette of the console.
2796 This is a 16-member array composed of values
2797 ranging from 0-255.
2798
2799 vt.default_red= [VT]
2800 Format: <red0>,<red1>,<red2>,...,<red15>
2801 Change the default red palette of the console.
2802 This is a 16-member array composed of values
2803 ranging from 0-255.
2804
2805 vt.default_utf8=
2806 [VT]
2807 Format=<0|1>
2808 Set system-wide default UTF-8 mode for all tty's.
2809 Default is 1, i.e. UTF-8 mode is enabled for all
2810 newly opened terminals.
2811
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002812 vt.global_cursor_default=
2813 [VT]
2814 Format=<-1|0|1>
2815 Set system-wide default for whether a cursor
2816 is shown on new VTs. Default is -1,
2817 i.e. cursors will be created by default unless
2818 overridden by individual drivers. 0 will hide
2819 cursors, 1 will display them.
2820
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 waveartist= [HW,OSS]
2822 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002823
Linus Torvalds1da177e2005-04-16 15:20:36 -07002824 wd33c93= [HW,SCSI]
2825 See header of drivers/scsi/wd33c93.c.
2826
2827 wd7000= [HW,SCSI]
2828 See header of drivers/scsi/wd7000.c.
2829
2830 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002831 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002832
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002833 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2834 default x2apic cluster mode on platforms
2835 supporting x2apic.
2836
Linus Torvalds1da177e2005-04-16 15:20:36 -07002837 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2838 xd_geo= See header of drivers/block/xd.c.
2839
2840 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002841 Format:
2842 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002843
Randy Dunlapa9913042005-10-23 12:57:11 -07002844______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845
2846TODO:
2847
2848 Add documentation for ALSA options.
2849 Add more DRM drivers.