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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050061 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020062 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070063 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070072 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070073 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
76 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.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300102 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500104 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 USB USB support is enabled.
106 USBHID USB Human Interface Device support is enabled.
107 V4L Video For Linux support is enabled.
108 VGA The VGA console has been enabled.
109 VT Virtual terminal support is enabled.
110 WDT Watchdog support is enabled.
111 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700112 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 X86-64 X86-64 architecture is enabled.
114 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700115 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200116 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117
118In addition, the following text indicates that the option:
119
120 BUGS= Relates to possible processor bugs on the said processor.
121 KNL Is a kernel start-up parameter.
122 BOOT Is a boot loader parameter.
123
124Parameters denoted with BOOT are actually interpreted by the boot
125loader, and have no meaning to the kernel directly.
126Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500127need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Karsten Weiss55588702007-02-13 13:26:21 +0100129There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700130See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100131
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
133a trailing = on the name of any parameter states that that parameter will
134be entered as an environment variable, whereas its absence indicates that
135it will appear as a kernel argument readable via /proc/cmdline by programs
136running once the system is up.
137
jens m. noedler9c4751f2006-09-29 02:00:27 -0700138The number of kernel parameters is not limited, but the length of the
139complete command line (parameters including spaces etc.) is limited to
140a fixed number of characters. This limit depends on the architecture
141and is between 256 and 4096 characters. It is defined in the file
142./include/asm/setup.h as COMMAND_LINE_SIZE.
143
144
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530145 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800146 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500147 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 force -- enable ACPI if default was off
149 off -- disable ACPI if default was on
150 noirq -- do not use ACPI for IRQ routing
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
Lin Mingaa2110c2010-04-08 14:34:27 +0800154 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
Randy Dunlap53471122008-03-12 18:10:51 -0400156 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Len Browna1fdcc02007-03-11 03:26:14 -0400158 acpi_apic_instance= [ACPI, IOAPIC]
159 Format: <int>
160 2: use 2nd APIC table, if available
161 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400162 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400163
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200164 acpi_backlight= [HW,ACPI]
165 acpi_backlight=vendor
166 acpi_backlight=video
167 If set to vendor, prefer vendor specific driver
168 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
169 of the ACPI video.ko driver.
170
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700171 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
172 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700174 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
175 debug output. Bits in debug_layer correspond to a
176 _COMPONENT in an ACPI source file, e.g.,
177 #define _COMPONENT ACPI_PCI_COMPONENT
178 Bits in debug_level correspond to a level in
179 ACPI_DEBUG_PRINT statements, e.g.,
180 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600181 The debug_level mask defaults to "info". See
182 Documentation/acpi/debug.txt for more information about
183 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600185 Enable processor driver info messages:
186 acpi.debug_layer=0x20000000
187 Enable PCI/PCI interrupt routing info messages:
188 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700189 Enable AML "Debug" output, i.e., stores to the Debug
190 object while interpreting AML:
191 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700192 Enable all messages related to ACPI hardware:
193 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200194
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700195 Some values produce so much output that the system is
196 unusable. The "log_buf_len" parameter may be useful
197 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800198
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700199 acpi_display_output= [HW,ACPI]
200 acpi_display_output=vendor
201 acpi_display_output=video
202 See above.
203
204 acpi_irq_balance [HW,ACPI]
205 ACPI will balance active IRQs
206 default in APIC mode
207
208 acpi_irq_nobalance [HW,ACPI]
209 ACPI will not move active IRQs (default)
210 default in PIC mode
211
212 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
213 Format: <irq>,<irq>...
214
215 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
216 use by PCI
217 Format: <irq>,<irq>...
218
219 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
220
221 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
222 Format: To spoof as Windows 98: ="Microsoft Windows"
223
224 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
225 acpi_osi="string1" # add string1 -- only one string
226 acpi_osi="!string2" # remove built-in string2
227 acpi_osi= # disable all strings
228
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530229 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700230 Override the pmtimer bug detection: force the kernel
231 to assume that this machine's pmtimer latches its value
232 and always returns good values.
233
Randy Dunlap4af94f32009-04-17 18:30:28 -0700234 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
235 Format: { level | edge | high | low }
236
237 acpi_serialize [HW,ACPI] force serialization of AML methods
238
239 acpi_skip_timer_override [HW,ACPI]
240 Recognize and ignore IRQ0/pin2 Interrupt Override.
241 For broken nForce2 BIOS resulting in XT-PIC timer.
242
243 acpi_sleep= [HW,ACPI] Sleep options
244 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800245 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700246 See Documentation/power/video.txt for information on
247 s3_bios and s3_mode.
248 s3_beep is for debugging; it makes the PC's speaker beep
249 as soon as the kernel's real-mode entry point is called.
250 s4_nohwsig prevents ACPI hardware signature from being
251 used during resume from hibernation.
252 old_ordering causes the ACPI 1.0 ordering of the _PTS
253 control method, with respect to putting devices into
254 low power states, to be enforced (the ACPI 2.0 ordering
255 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200256 nonvs prevents the kernel from saving/restoring the
257 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800258 sci_force_enable causes the kernel to set SCI_EN directly
259 on resume from S1/S3 (which is against the ACPI spec,
260 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700261
262 acpi_use_timer_override [HW,ACPI]
263 Use timer override. For some broken Nvidia NF5 boards
264 that require a timer override, but don't have HPET
265
Luca Tettamanti7e905602009-03-30 00:01:27 +0200266 acpi_enforce_resources= [ACPI]
267 { strict | lax | no }
268 Check for resource conflicts between native drivers
269 and ACPI OperationRegions (SystemIO and SystemMemory
270 only). IO ports and memory declared in ACPI might be
271 used by the ACPI subsystem in arbitrary AML code and
272 can interfere with legacy drivers.
273 strict (default): access to resources claimed by ACPI
274 is denied; legacy drivers trying to access reserved
275 resources will fail to bind to device using them.
276 lax: access to resources claimed by ACPI is allowed;
277 legacy drivers trying to access reserved resources
278 will bind successfully but a warning message is logged.
279 no: ACPI OperationRegions are not marked as reserved,
280 no further checks are performed.
281
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 ad1848= [HW,OSS]
283 Format: <io>,<irq>,<dma>,<dma2>,<type>
284
Randy Dunlap4af94f32009-04-17 18:30:28 -0700285 add_efi_memmap [EFI; X86] Include EFI memory map in
286 kernel's map of available physical RAM.
287
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 advansys= [HW,SCSI]
289 See header of drivers/scsi/advansys.c.
290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 aedsp16= [HW,OSS] Audio Excel DSP 16
292 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
293 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700294
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700295 agp= [AGP]
296 { off | try_unsupported }
297 off: disable AGP support
298 try_unsupported: try to drive unsupported chipsets
299 (may crash computer or cause data corruption)
300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 aha152x= [HW,SCSI]
302 See Documentation/scsi/aha152x.txt.
303
304 aha1542= [HW,SCSI]
305 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
306
307 aic7xxx= [HW,SCSI]
308 See Documentation/scsi/aic7xxx.txt.
309
310 aic79xx= [HW,SCSI]
311 See Documentation/scsi/aic79xx.txt.
312
Russell Kingd944d542010-02-20 16:13:29 +0000313 alignment= [KNL,ARM]
314 Allow the default userspace alignment fault handler
315 behaviour to be specified. Bit 0 enables warnings,
316 bit 1 enables fixups, and bit 2 sends a segfault.
317
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
320 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900321 fullflush - enable flushing of IO/TLB entries when
322 they are unmapped. Otherwise they are
323 flushed before they will be reused, which
324 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200325 off - do not initialize any AMD IOMMU found in
326 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 amijoy.map= [HW,JOY] Amiga joystick support
329 Map of devices attached to JOY0DAT and JOY1DAT
330 Format: <a>,<b>
331 See also Documentation/kernel/input/joystick.txt
332
333 analog.map= [HW,JOY] Analog joystick and gamepad support
334 Specifies type or capabilities of an analog joystick
335 connected to one of 16 gameports
336 Format: <type1>,<type2>,..<type16>
337
Randy Dunlapa9913042005-10-23 12:57:11 -0700338 apc= [HW,SPARC]
339 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 Format: noidle
341 Disable APC CPU standby support. SPARCstation-Fox does
342 not play well with APC CPU idle - disable it if you have
343 APC and your system crashes randomly.
344
Randy Dunlapca1eda22009-05-06 16:02:58 -0700345 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700346 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 Format: { quiet (default) | verbose | debug }
348 Change the amount of debugging information output
349 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700350
Brian Haleyb0f83b22010-02-04 13:36:50 -0800351 autoconf= [IPV6]
352 See Documentation/networking/ipv6.txt.
353
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400354 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
355 Limit apic dumping. The parameter defines the maximal
356 number of local apics being dumped. Also it is possible
357 to set it to "all" by meaning -- no limit here.
358 Format: { 1 (default) | 2 | ... | all }.
359 The parameter valid if only apic=debug or
360 apic=verbose is specified.
361 Example: apic=debug show_lapic=all
362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700364 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
367 Format: <io>,<irq>,<nodeID>
368
369 ataflop= [HW,M68k]
370
371 atarimouse= [HW,MOUSE] Atari Mouse
372
373 atascsi= [HW,SCSI] Atari SCSI
374
375 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
376 EzKey and similar keyboards
377
378 atkbd.reset= [HW] Reset keyboard during initialization
379
Randy Dunlapa9913042005-10-23 12:57:11 -0700380 atkbd.set= [HW] Select keyboard code set
381 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
384 keyboards
385
386 atkbd.softraw= [HW] Choose between synthetic and real raw mode
387 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700388
389 atkbd.softrepeat= [HW]
390 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391
392 autotest [IA64]
393
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 baycom_epp= [HW,AX25]
395 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700396
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
398 Format: <io>,<mode>
399 See header of drivers/net/hamradio/baycom_par.c.
400
Randy Dunlapa9913042005-10-23 12:57:11 -0700401 baycom_ser_fdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 Format: <io>,<irq>,<mode>[,<baud>]
404 See header of drivers/net/hamradio/baycom_ser_fdx.c.
405
Randy Dunlapa9913042005-10-23 12:57:11 -0700406 baycom_ser_hdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 Format: <io>,<irq>,<mode>
409 See header of drivers/net/hamradio/baycom_ser_hdx.c.
410
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700411 boot_delay= Milliseconds to delay each printk during boot.
412 Values larger than 10 seconds (10000) are changed to
413 no delay (0).
414 Format: integer
415
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700416 bootmem_debug [KNL] Enable bootmem allocator debug messages.
417
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700419 bttv.radio= Most important insmod options are available as
420 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
422 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
423
424 BusLogic= [HW,SCSI]
425 See drivers/scsi/BusLogic.c, comment before function
426 BusLogic_ParseDriverOptions().
427
428 c101= [NET] Moxa C101 synchronous serial card
429
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700430 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 Sometimes CPU hardware bugs make them report the cache
432 size incorrectly. The kernel will attempt work arounds
433 to fix known problems, but for some CPUs it is not
434 possible to determine what the correct size should be.
435 This option provides an override for these situations.
436
James Morris20510f22007-10-16 23:31:32 -0700437 capability.disable=
438 [SECURITY] Disable capabilities. This would normally
439 be used only if an alternative security model is to be
440 configured. Potentially dangerous and should only be
441 used if you are entirely sure of the consequences.
442
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100443 ccw_timeout_log [S390]
444 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445
Paul Menage8bab8dd2008-04-04 14:29:57 -0700446 cgroup_disable= [KNL] Disable a particular controller
447 Format: {name of the controller(s) to disable}
448 {Currently supported controllers - "memory"}
449
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 checkreqprot [SELINUX] Set initial checkreqprot flag value.
451 Format: { "0" | "1" }
452 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700453 0 -- check protection applied by kernel (includes
454 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 1 -- check protection requested by application.
456 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700457 Value can be changed at runtime via
458 /selinux/checkreqprot.
459
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100460 cio_ignore= [S390]
461 See Documentation/s390/CommonIO for details.
462
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700463 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700464 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200465 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700466 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200467 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 Format: { pit | tsc | cyclone | pmtmr }
469
John Stultz592913e2010-07-13 17:56:20 -0700470 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700471 Format: <string>
472 Override the default clocksource and use the clocksource
473 with the name specified.
474 Some clocksource names to choose from, depending on
475 the platform:
476 [all] jiffies (this is the base, fallback clocksource)
477 [ACPI] acpi_pm
478 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
479 pxa_timer,timer3,32k_counter,timer0_1
480 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700481 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700482 scx200_hrt on Geode; cyclone on IBM x440
483 [MIPS] MIPS
484 [PARISC] cr16
485 [S390] tod
486 [SH] SuperH
487 [SPARC64] tick
488 [X86-64] hpet,tsc
489
Andi Kleenac72e782008-01-30 13:33:21 +0100490 clearcpuid=BITNUM [X86]
491 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800492 arch/x86/include/asm/cpufeature.h for the valid bit
493 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100494 stable over kernel options, but the vendor specific
495 ones should be.
496 Also note that user programs calling CPUID directly
497 or using the feature without checking anything
498 will still see it. This just prevents it from
499 being used by the kernel or shown in /proc/cpuinfo.
500 Also note the kernel might malfunction if you disable
501 some critical bits.
502
Robert Jennings14f966e2009-04-15 05:55:32 +0000503 cmo_free_hint= [PPC] Format: { yes | no }
504 Specify whether pages are marked as being inactive
505 when they are freed. This is used in CMO environments
506 to determine OS memory pressure for page stealing by
507 a hypervisor.
508 Default: yes
509
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530510 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100511 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100512 Range: 0 - 8192
513 Default: 64
514
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700516 Format:
517 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518
519 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
520 Format: <io>[,<irq>]
521
Randy Dunlapa9913042005-10-23 12:57:11 -0700522 com90xx= [HW,NET]
523 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 Format: <io>[,<irq>[,<memstart>]]
525
526 condev= [HW,S390] console device
527 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 console= [KNL] Output console device and options.
530
531 tty<n> Use the virtual console device <n>.
532
533 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800534 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800536 the form "bbbbpnf", where "bbbb" is the baud rate,
537 "p" is parity ("n", "o", or "e"), "n" is number of
538 bits, and "f" is flow control ("r" for RTS or
539 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800541 See Documentation/serial-console.txt for more
542 information. See
543 Documentation/networking/netconsole.txt for an
544 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700546 uart[8250],io,<addr>[,options]
547 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 Start an early, polled-mode console on the 8250/16550
549 UART at the specified I/O port or MMIO address,
550 switching to the matching ttyS device later. The
551 options are the same as for ttyS, above.
552
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700553 If the device connected to the port is not a TTY but a braille
554 device, prepend "brl," before the device type, for instance
555 console=brl,ttyS0
556 For now, only VisioBraille is supported.
557
Daniel Mackf324edc2009-06-16 15:33:52 -0700558 consoleblank= [KNL] The console blank (screen saver) timeout in
559 seconds. Defaults to 10*60 = 10mins. A value of 0
560 disables the blank timer.
561
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800562 coredump_filter=
563 [KNL] Change the default value for
564 /proc/<pid>/coredump_filter.
565 See also Documentation/filesystems/proc.txt.
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700568 Format:
569 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700571 crashkernel=nn[KMG]@ss[KMG]
572 [KNL] Reserve a chunk of physical memory to
573 hold a kernel to switch to with kexec on panic.
574
Bernhard Wallefb391592007-10-18 23:41:02 -0700575 crashkernel=range1:size1[,range2:size2,...][@offset]
576 [KNL] Same as above, but depends on the memory
577 in the running system. The syntax of range is
578 start-[end] where start and end are both
579 a memory unit (amount[KMG]). See also
580 Documentation/kdump/kdump.txt for a example.
581
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 cs89x0_dma= [HW,NET]
583 Format: <dma>
584
585 cs89x0_media= [HW,NET]
586 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700587
Randy Dunlapa9913042005-10-23 12:57:11 -0700588 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 See header of drivers/s390/block/dasd_devmap.c.
590
591 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
592 (one device per port)
593 Format: <port#>,<type>
594 See also Documentation/input/joystick-parport.txt
595
596 debug [KNL] Enable kernel debugging (events log level).
597
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700598 debug_locks_verbose=
599 [KNL] verbose self-tests
600 Format=<0|1>
601 Print debugging info while doing the locking API
602 self-tests.
603 We default to 0 (no extra messages), setting it to
604 1 will print _a lot_ more information - normally
605 only useful to kernel developers.
606
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700607 debug_objects [KNL] Enable object debugging
608
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500609 no_debug_objects
610 [KNL] Disable object debugging
611
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200612 debugpat [X86] Enable PAT debugging
613
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200614 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 Format: <area>[,<node>]
616 See also Documentation/networking/decnet.txt.
617
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700618 default_hugepagesz=
619 [same as hugepagesz=] The size of the default
620 HugeTLB page size. This is the size represented by
621 the legacy /proc/ hugepages APIs, used for SHM, and
622 default size when mounting hugetlbfs filesystems.
623 Defaults to the default architecture's huge page size
624 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700625
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 dhash_entries= [KNL]
627 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 digi= [HW,SERIAL]
630 IO parameters + enable/disable command.
631
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000634 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635
Brian Haleyb0f83b22010-02-04 13:36:50 -0800636 disable= [IPV6]
637 See Documentation/networking/ipv6.txt.
638
639 disable_ipv6= [IPV6]
640 See Documentation/networking/ipv6.txt.
641
Yinghai Lu95ffa242008-04-29 03:52:33 -0700642 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700643 The kernel tries to adjust MTRR layout from continuous
644 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700645 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700646
Yinghai Lu093af8d2008-01-30 13:33:32 +0100647 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530653 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 Disable PIN 1 of APIC timer
655 Can be useful to work around chipset bugs.
656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 dmasound= [HW,OSS] Sound subsystem buffers
658
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700659 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
660 this option disables the debugging code at boot.
661
662 dma_debug_entries=<number>
663 This option allows to tune the number of preallocated
664 entries for DMA-API debugging code. One entry is
665 required per DMA-API allocation. Use this if the
666 DMA-API debugging code disables itself because the
667 architectural default is too low.
668
Joerg Roedel1745de52009-05-22 21:49:51 +0200669 dma_debug_driver=<driver_name>
670 With this option the DMA-API debugging driver
671 filter feature can be enabled at boot time. Just
672 pass the driver to filter for as the parameter.
673 The filter can be disabled or changed to another
674 driver later using sysfs.
675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 dscc4.setup= [NET]
677
678 dtc3181e= [HW,SCSI]
679
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700680 dynamic_printk Enables pr_debug()/dev_dbg() calls if
681 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
682 These can also be switched on/off via
683 <debugfs>/dynamic_printk/modules
684
685 earlycon= [KNL] Output early console device and options.
686 uart[8250],io,<addr>[,options]
687 uart[8250],mmio,<addr>[,options]
688 Start an early, polled-mode console on the 8250/16550
689 UART at the specified I/O port or MMIO address.
690 The options are the same as for ttyS, above.
691
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530692 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 earlyprintk=vga
694 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500695 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500696 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697
Randy Dunlapa9913042005-10-23 12:57:11 -0700698 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 takes over.
700
Yinghai Lu5c059172008-07-24 17:29:40 -0700701 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
703 Currently only ttyS0 and ttyS1 are supported.
704
705 Interaction with the standard serial driver is not
706 very good.
707
708 The VGA output is eventually overwritten by the real
709 console.
710
Jason Wessel97311912010-05-20 21:04:30 -0500711 ekgdboc= [X86,KGDB] Allow early kernel console debugging
712 ekgdboc=kbd
713
714 This is desgined to be used in conjunction with
715 the boot argument: earlyprintk=vga
716
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 eata= [HW,SCSI]
718
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700720 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 eisa_irq_edge= [PARISC,HW]
723 See header of drivers/parisc/eisa.c.
724
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700725 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700727 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728
729 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800730 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700731 See Documentation/block/as-iosched.txt and
732 Documentation/block/deadline-iosched.txt for details.
733
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530734 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700735 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800736 image elf header. Generally kexec loader will
737 pass this option to capture kernel.
738 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700740 enable_mtrr_cleanup [X86]
741 The kernel tries to adjust MTRR layout from continuous
742 to discrete, to make X server driver able to add WB
743 entry later. This parameter enables that.
744
Randy Dunlapca1eda22009-05-06 16:02:58 -0700745 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700746 Enable PIN 1 of APIC timer
747 Can be useful to work around chipset bugs
748 (in particular on some ATI chipsets).
749 The kernel tries to set a reasonable default.
750
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 enforcing [SELINUX] Set initial enforcing status.
752 Format: {"0" | "1"}
753 See security/selinux/Kconfig help text.
754 0 -- permissive (log only, no denials).
755 1 -- enforcing (deny and log).
756 Default value is 0.
757 Value can be changed at runtime via /selinux/enforce.
758
Huang Yinga08f82d2010-05-18 14:35:21 +0800759 erst_disable [ACPI]
760 Disable Error Record Serialization Table (ERST)
761 support.
762
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 ether= [HW,NET] Ethernet cards parameters
764 This option is obsoleted by the "netdev=" option, which
765 has equivalent usage. See its documentation for details.
766
Akinobu Mitade1ba092006-12-08 02:39:42 -0800767 failslab=
768 fail_page_alloc=
769 fail_make_request=[KNL]
770 General fault injection mechanism.
771 Format: <interval>,<probability>,<space>,<times>
772 See also /Documentation/fault-injection/.
773
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 fd_mcs= [HW,SCSI]
775 See header of drivers/scsi/fd_mcs.c.
776
777 fdomain= [HW,SCSI]
778 See header of drivers/scsi/fdomain.c.
779
780 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000781 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782
Alex Chiangf13ae302008-05-08 14:03:23 -0600783 force_pal_cache_flush
784 [IA-64] Avoid check_sal_cache_flush which may hang on
785 buggy SAL_CACHE_FLUSH implementations. Using this
786 parameter will force ia64_sal_cache_flush to call
787 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
788
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100789 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400790 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100791 as early as possible in order to facilitate early
792 boot debugging.
793
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200794 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400795 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200796 If no parameter is passed, ftrace will dump
797 buffers of all CPUs, but if you pass orig_cpu, it will
798 dump only the buffer of the CPU that triggered the
799 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400800
801 ftrace_filter=[function-list]
802 [FTRACE] Limit the functions traced by the function
803 tracer at boot up. function-list is a comma separated
804 list of functions. This list can be changed at run
805 time by the set_ftrace_filter file in the debugfs
806 tracing directory.
807
808 ftrace_notrace=[function-list]
809 [FTRACE] Do not trace the functions specified in
810 function-list. This list can be changed at run time
811 by the set_ftrace_notrace file in the debugfs
812 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100813
Stefan Assmann369bc182009-10-12 22:17:21 +0200814 ftrace_graph_filter=[function-list]
815 [FTRACE] Limit the top level callers functions traced
816 by the function graph tracer at boot up.
817 function-list is a comma separated list of functions
818 that can be changed at run time by the
819 set_graph_function file in the debugfs tracing directory.
820
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 gamecon.map[2|3]=
822 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
823 support via parallel port (up to 5 devices per port)
824 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
825 See also Documentation/input/joystick-parport.txt
826
827 gamma= [HW,DRM]
828
Yinghai Luaaf23042008-01-30 13:33:09 +0100829 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
830 Format: off | on
831 default: on
832
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700833 gcov_persist= [GCOV] When non-zero (default), profiling data for
834 kernel modules is saved and remains accessible via
835 debugfs, even when the module is unloaded/reloaded.
836 When zero, profiling data is discarded and associated
837 debugfs files are removed at module unload time.
838
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 gdth= [HW,SCSI]
840 See header of drivers/scsi/gdth.c.
841
842 gpt [EFI] Forces disk with valid GPT signature but
843 invalid Protective MBR to be treated as GPT.
844
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 gvp11= [HW,SCSI]
846
847 hashdist= [KNL,NUMA] Large hashes allocated during boot
848 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700849 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700850 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851
852 hcl= [IA-64] SGI's Hardware Graph compatibility layer
853
854 hd= [EIDE] (E)IDE hard drive subsystem geometry
855 Format: <cyl>,<head>,<sect>
856
Huang Yingea8c0712010-05-18 14:35:15 +0800857 hest_disable [ACPI]
858 Disable Hardware Error Source Table (HEST) support;
859 corresponding firmware-first mode error processing
860 logic will be disabled.
861
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
863 size of <nn>. This works even on boxes that have no
864 highmem otherwise. This also works to reduce highmem
865 size on bigger boxes.
866
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800867 highres= [KNL] Enable/disable high resolution timer mode.
868 Valid parameters: "on", "off"
869 Default: "on"
870
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 hisax= [HW,ISDN]
872 See Documentation/isdn/README.HiSax.
873
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700874 hlt [BUGS=ARM,SH]
875
876 hpet= [X86-32,HPET] option to control HPET usage
877 Format: { enable (default) | disable | force |
878 verbose }
879 disable: disable HPET and use PIT instead
880 force: allow force enabled of undocumented chips (ICH4,
881 VIA, nVidia)
882 verbose: show contents of HPET registers during setup
883
Andi Kleenb4718e62008-07-23 21:27:51 -0700884 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
885 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700886 On x86-64 and powerpc, this option can be specified
887 multiple times interleaved with hugepages= to reserve
888 huge pages of different sizes. Valid pages sizes on
889 x86-64 are 2M (when the CPU supports "pse") and 1G
890 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700891 Note that 1GB pages can only be allocated at boot time
892 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900893
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100894 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
895 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100896 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
897 If specified, z/VM IUCV HVC accepts connections
898 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100899
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700900 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700901 or register an additional I2C bus that is not
902 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700903 Format:
904 <bus_id>,<clkrate>
905
Jiri Kosina36d95732008-10-06 02:51:09 -0400906 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200908 i8042.dumbkbd [HW] Pretend that controller can only read data from
909 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 (Don't attempt to blink the leds)
911 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500912 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400913 i8042.noloop [HW] Disable the AUX Loopback command while probing
914 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 i8042.nomux [HW] Don't check presence of an active multiplexing
916 controller
917 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
918 controllers
919 i8042.panicblink=
920 [HW] Frequency with which keyboard LEDs should blink
921 when kernel panics (default is 0.5 sec)
922 i8042.reset [HW] Reset the controller during init and cleanup
923 i8042.unlock [HW] Unlock (ignore) the keylock
924
925 i810= [HW,DRM]
926
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700927 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
928 indicates that the driver is running on unsupported
929 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
931 does not match list of supported models.
932 i8k.power_status
933 [HW] Report power status in /proc/i8k
934 (disabled by default)
935 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
936 capability is set.
937
938 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
939 See Documentation/mca.txt.
940
941 icn= [HW,ISDN]
942 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
943
David Fries0af80c02009-02-25 20:28:21 +0100944 ide-core.nodma= [HW] (E)IDE subsystem
945 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200946 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
947 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100948 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700950 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
951 Claim all unknown PCI IDE storage controllers.
952
Andi Kleenf039b752007-05-02 19:27:12 +0200953 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800954 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
955 Poll forces a polling idle loop that can slightly
956 improve the performance of waking up a idle CPU, but
957 will use a lot of power and make the system run hot.
958 Not recommended.
959 idle=mwait: On systems which support MONITOR/MWAIT but
960 the kernel chose to not use it because it doesn't save
961 as much power as a normal idle loop, use the
962 MONITOR/MWAIT idle loop anyways. Performance should be
963 the same as idle=poll.
964 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800965 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800966 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700967
Ingo Molnar792908222006-12-06 20:40:51 -0800968 ignore_loglevel [KNL]
969 Ignore loglevel setting - this will print /all/
970 kernel messages to the console. Useful for debugging.
971
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 ihash_entries= [KNL]
973 Set number of hash buckets for inode cache.
974
Mimi Zohar3323eec92009-02-04 09:06:58 -0500975 ima_audit= [IMA]
976 Format: { "0" | "1" }
977 0 -- integrity auditing messages. (Default)
978 1 -- enable informational integrity auditing messages.
979
980 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700981 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500982 default: "sha1"
983
Eric Paris5789ba32009-05-21 15:47:06 -0400984 ima_tcb [IMA]
985 Load a policy which meets the needs of the Trusted
986 Computing Base. This means IMA will measure all
987 programs exec'd, files mmap'd for exec, and all files
988 opened for read by uid=0.
989
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 in2000= [HW,SCSI]
991 See header of drivers/scsi/in2000.c.
992
993 init= [KNL]
994 Format: <full_path>
995 Run specified binary instead of /sbin/init as init
996 process.
997
998 initcall_debug [KNL] Trace initcalls as they are executed. Useful
999 for working out where the kernel is dying during
1000 startup.
1001
1002 initrd= [BOOT] Specify the location of the initial ramdisk
1003
1004 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1005 Format: <irq>
1006
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001007 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001008 on
1009 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001010 off
1011 Disable intel iommu driver.
1012 igfx_off [Default Off]
1013 By default, gfx is mapped as normal device. If a gfx
1014 device has a dedicated DMAR unit, the DMAR unit is
1015 bypassed by not enabling DMAR with this option. In
1016 this case, gfx device will use physical address for
1017 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001018 forcedac [x86_64]
1019 With this option iommu will not optimize to look
1020 for io virtual address below 32 bit forcing dual
1021 address cycle on pci bus for cards supporting greater
1022 than 32 bit addressing. The default is to look
1023 for translation below 32 bit and if not available
1024 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001025 strict [Default Off]
1026 With this option on every unmap_single operation will
1027 result in a hardware IOTLB flush operation as opposed
1028 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001029
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001030 inttest= [IA64]
1031
1032 iomem= Disable strict checking of access to MMIO memory
1033 strict regions from userspace.
1034 relaxed
1035
1036 iommu= [x86]
1037 off
1038 force
1039 noforce
1040 biomerge
1041 panic
1042 nopanic
1043 merge
1044 nomerge
1045 forcesac
1046 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001047 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001048
1049 io7= [HW] IO7 for Marvel based alpha systems
1050 See comment before marvel_specify_io7 in
1051 arch/alpha/kernel/core_marvel.c.
1052
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301053 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001054 0x80
1055 Standard port 0x80 based delay
1056 0xed
1057 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001058 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001059 Simple two microseconds delay
1060 none
1061 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001062
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001064 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065
1066 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001067 See comment before ip2_setup() in
1068 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069
1070 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1071 See header of drivers/scsi/ips.c.
1072
Alan Cox200803d2005-06-28 20:45:18 -07001073 irqfixup [HW]
1074 When an interrupt is not handled search all handlers
1075 for it. Intended to get systems with badly broken
1076 firmware running.
1077
1078 irqpoll [HW]
1079 When an interrupt is not handled search all handlers
1080 for it. Also check all handlers each timer
1081 interrupt. Intended to get systems with badly broken
1082 firmware running.
1083
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001085 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086
1087 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001088 Format:
1089 <cpu number>,...,<cpu number>
1090 or
Li Zefanb225d442008-11-06 12:53:39 -08001091 <cpu number>-<cpu number>
1092 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001093 or a mixture
1094 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001095
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 This option can be used to specify one or more CPUs
1097 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001098 algorithms. You can move a process onto or off an
1099 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 <cpu number> begins at 0 and the maximum value is
1101 "number of CPUs in system - 1".
1102
1103 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001104 alternative -- manually setting the CPU mask of all
1105 tasks in the system -- can cause problems and
1106 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107
Randy Dunlapa9913042005-10-23 12:57:11 -07001108 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109
1110 js= [HW,JOY] Analog joystick
1111 See Documentation/input/joystick.txt.
1112
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001113 keepinitrd [HW,ARM]
1114
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301115 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001116 specifies the amount of memory usable by the kernel
1117 for non-movable allocations. The requested amount is
1118 spread evenly throughout all nodes in the system. The
1119 remaining memory in each node is used for Movable
1120 pages. In the event, a node is too small to have both
1121 kernelcore and Movable pages, kernelcore pages will
1122 take priority and other nodes will have a larger number
1123 of kernelcore pages. The Movable zone is used for the
1124 allocation of pages that may be reclaimed or moved
1125 by the page migration subsystem. This means that
1126 HugeTLB pages may not be allocated from this zone.
1127 Note that allocations like PTEs-from-HighMem still
1128 use the HighMem zone if it exists, and the Normal
1129 zone if it does not.
1130
Jason Wessel4fe1da42010-05-20 21:04:31 -05001131 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1132 Format: <Controller#>[,poll interval]
1133 The controller # is the number of the ehci usb debug
1134 port as it is probed via PCI. The poll interval is
1135 optional and is the number seconds in between
1136 each poll cycle to the debug port in case you need
1137 the functionality for interrupting the kernel with
1138 gdb or control-c on the dbgp connection. When
1139 not using this parameter you use sysrq-g to break into
1140 the kernel debugger.
1141
Jason Wessel84c08fd2010-05-20 21:04:24 -05001142 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001143 Requires a tty driver that supports console polling,
1144 or a supported polling keyboard driver (non-usb).
1145 Serial only format: <serial_device>[,baud]
1146 keyboard only format: kbd
1147 keyboard and serial format: kbd,<serial_device>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001148
Jason Wessel84c08fd2010-05-20 21:04:24 -05001149 kgdbwait [KGDB] Stop kernel execution and enter the
1150 kernel debugger at the earliest opportunity.
1151
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001152 kmac= [MIPS] korina ethernet MAC address.
1153 Configure the RouterBoard 532 series on-chip
1154 Ethernet adapter MAC address.
1155
Catalin Marinas04f70332009-06-11 13:22:39 +01001156 kmemleak= [KNL] Boot-time kmemleak enable/disable
1157 Valid arguments: on, off
1158 Default: on
1159
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301160 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001161 in oops dumps.
1162
Andre Przywarafef07aa2009-07-10 14:20:35 +02001163 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1164 Default is 0 (don't ignore, but inject #GP)
1165
1166 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1167 Default is 1 (enabled)
1168
1169 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1170 Default is 0 (off)
1171
1172 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1173 for all guests.
1174 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1175
1176 kvm-intel.bypass_guest_pf=
1177 [KVM,Intel] Disables bypassing of guest page faults
1178 on Intel chips. Default is 1 (enabled)
1179
1180 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1181 (virtualized MMU) support on capable Intel chips.
1182 Default is 1 (enabled)
1183
1184 kvm-intel.emulate_invalid_guest_state=
1185 [KVM,Intel] Enable emulation of invalid guest states
1186 Default is 0 (disabled)
1187
1188 kvm-intel.flexpriority=
1189 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1190 Default is 1 (enabled)
1191
1192 kvm-intel.unrestricted_guest=
1193 [KVM,Intel] Disable unrestricted guest feature
1194 (virtualized real and unpaged mode) on capable
1195 Intel chips. Default is 1 (enabled)
1196
1197 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1198 feature (tagged TLBs) on capable Intel chips.
1199 Default is 1 (enabled)
1200
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 l2cr= [PPC]
1202
Robert Brosea78bfbf2008-03-29 07:20:23 +11001203 l3cr= [PPC]
1204
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001205 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001206 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301208 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001209 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001210
FD Camifcb71f62008-01-06 19:08:56 +01001211 libata.dma= [LIBATA] DMA control
1212 libata.dma=0 Disable all PATA and SATA DMA
1213 libata.dma=1 PATA and SATA Disk DMA only
1214 libata.dma=2 ATAPI (CDROM) DMA only
1215 libata.dma=4 Compact Flash DMA only
1216 Combinations also work, so libata.dma=3 enables DMA
1217 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001218
1219 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1220 libata.ignore_hpa=0 keep BIOS limits (default)
1221 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001222
Dave Jones78e70c22007-09-27 11:50:13 -04001223 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1224 when set.
1225 Format: <int>
1226
Tejun Heo33267322008-02-13 09:15:09 +09001227 libata.force= [LIBATA] Force configurations. The format is comma
1228 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001229 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001230 matching port, link or device. Basically, it matches
1231 the ATA ID string printed on console by libata. If
1232 the whole ID part is omitted, the last PORT and DEVICE
1233 values are used. If ID hasn't been specified yet, the
1234 configuration applies to all ports, links and devices.
1235
1236 If only DEVICE is omitted, the parameter applies to
1237 the port and all links and devices behind it. DEVICE
1238 number of 0 either selects the first device or the
1239 first fan-out link behind PMP device. It does not
1240 select the host link. DEVICE number of 15 selects the
1241 host link and device attached to it.
1242
1243 The VAL specifies the configuration to force. As long
1244 as there's no ambiguity shortcut notation is allowed.
1245 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1246 The following configurations can be forced.
1247
1248 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1249 Any ID with matching PORT is used.
1250
1251 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1252
1253 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1254 udma[/][16,25,33,44,66,100,133] notation is also
1255 allowed.
1256
1257 * [no]ncq: Turn on or off NCQ.
1258
Tejun Heo05944bd2008-08-13 20:19:09 +09001259 * nohrst, nosrst, norst: suppress hard, soft
1260 and both resets.
1261
Tejun Heo43c9c592010-05-23 12:59:11 +02001262 * dump_id: dump IDENTIFY data.
1263
Tejun Heo33267322008-02-13 09:15:09 +09001264 If there are multiple matching configurations changing
1265 the same attribute, the last one is used.
1266
Yinghai Lu95f72d12010-07-12 14:36:09 +10001267 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001268
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001270 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001272 lockd.nlm_grace_period=P [NFS] Assign grace period.
1273 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001275 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1276 Format: <integer>
1277
1278 lockd.nlm_timeout=T [NFS] Assign timeout value.
1279 Format: <integer>
1280
1281 lockd.nlm_udpport=M [NFS] Assign UDP port.
1282 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283
1284 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1285 Format: <irq>
1286
1287 loglevel= All Kernel Messages with a loglevel smaller than the
1288 console loglevel will be printed to the console. It can
1289 also be changed with klogd or other programs. The
1290 loglevels are defined as follows:
1291
1292 0 (KERN_EMERG) system is unusable
1293 1 (KERN_ALERT) action must be taken immediately
1294 2 (KERN_CRIT) critical conditions
1295 3 (KERN_ERR) error conditions
1296 4 (KERN_WARNING) warning conditions
1297 5 (KERN_NOTICE) normal but significant condition
1298 6 (KERN_INFO) informational
1299 7 (KERN_DEBUG) debug-level messages
1300
1301 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001302 Format: { n | nk | nM }
1303 n must be a power of two. The default size
1304 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
Randy Dunlapaccaa242007-10-16 01:29:37 -07001306 logo.nologo [FB] Disables display of the built-in Linux logo.
1307 This may be used to provide more screen space for
1308 kernel log messages and is useful when debugging
1309 kernel boot problems.
1310
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 lp=0 [LP] Specify parallel ports to use, e.g,
1312 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1313 lp=reset first parallel port). 'lp=0' disables the
1314 lp=auto printer driver. 'lp=reset' (which can be
1315 specified in addition to the ports) causes
1316 attached printers to be reset. Using
1317 lp=port1,port2,... specifies the parallel ports
1318 to associate lp devices with, starting with
1319 lp0. A port specification may be 'none' to skip
1320 that lp device, or a parport name such as
1321 'parport0'. Specifying 'lp=auto' instead of a
1322 port specification list means that device IDs
1323 from each port should be examined, to see if
1324 an IEEE 1284-compliant printer is attached; if
1325 so, the driver will manage that printer.
1326 See also header of drivers/char/lp.c.
1327
1328 lpj=n [KNL]
1329 Sets loops_per_jiffy to given constant, thus avoiding
1330 time-consuming boot-time autodetection (up to 250 ms per
1331 CPU). 0 enables autodetection (default). To determine
1332 the correct value for your kernel, boot with normal
1333 autodetection and see what value is printed. Note that
1334 on SMP systems the preset will be applied to all CPUs,
1335 which is likely to cause problems if your CPUs need
1336 significantly divergent settings. An incorrect value
1337 will cause delays in the kernel to be wrong, leading to
1338 unpredictable I/O errors and other breakage. Although
1339 unlikely, in the extreme case this might damage your
1340 hardware.
1341
1342 ltpc= [NET]
1343 Format: <io>,<irq>,<dma>
1344
Randy Dunlapa9913042005-10-23 12:57:11 -07001345 mac5380= [HW,SCSI] Format:
1346 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347
Randy Dunlapa9913042005-10-23 12:57:11 -07001348 machvec= [IA64] Force the use of a particular machine-vector
1349 (machvec) in a generic kernel.
1350 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351
Wu Zhangjin3209e702009-07-02 23:27:12 +08001352 machtype= [Loongson] Share the same kernel image file between different
1353 yeeloong laptop.
1354 Example: machtype=lemote-yeeloong-2f-7inch
1355
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001356 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1357 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
1359 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001360 should make use of. maxcpus=n : n >= 0 limits the
1361 kernel to using 'n' processors. n=0 is a special case,
1362 it is equivalent to "nosmp", which also disables
1363 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001365 max_loop= [LOOP] Maximum number of loopback devices that can
1366 be mounted
1367 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001368
Randy Dunlapa9913042005-10-23 12:57:11 -07001369 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 Should be between 1 and 2^32-1.
1371
1372 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001373 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 Should be between 1 and 16384.
1375
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 mcatest= [IA-64]
1377
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001378 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
Uwe Hermann71cced62008-10-20 09:32:21 -07001380 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 md= [HW] RAID subsystems devices and level
1383 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001384
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 mdacon= [MDA]
1386 Format: <first>,<last>
1387 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001388
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1390 Amount of memory to be used when the kernel is not able
1391 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001392 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 address space collisions. Without memmap= PCI devices
1394 could be placed at addresses belonging to unused RAM.
1395
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001396 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 memory.
1398
Paul Mundt6902aa82008-09-21 17:14:42 +09001399 memchunk=nn[KMG]
1400 [KNL,SH] Allow user to override the default size for
1401 per-device physically contiguous DMA buffers.
1402
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301403 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 E820 memory map, as specified by the user.
1405 Such memmap=exactmap lines can be constructed based on
1406 BIOS output or other requirements. See the memmap=nn@ss
1407 option description.
1408
1409 memmap=nn[KMG]@ss[KMG]
1410 [KNL] Force usage of a specific region of memory
1411 Region of memory to be used, from ss to ss+nn.
1412
1413 memmap=nn[KMG]#ss[KMG]
1414 [KNL,ACPI] Mark specific memory as ACPI data.
1415 Region of memory to be used, from ss to ss+nn.
1416
1417 memmap=nn[KMG]$ss[KMG]
1418 [KNL,ACPI] Mark specific memory as reserved.
1419 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001420 Example: Exclude memory from 0x18690000-0x1869ffff
1421 memmap=64K$0x18690000
1422 or
1423 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001425 memory_corruption_check=0/1 [X86]
1426 Some BIOSes seem to corrupt the first 64k of
1427 memory when doing things like suspend/resume.
1428 Setting this option will scan the memory
1429 looking for corruption. Enabling this will
1430 both detect corruption and prevent the kernel
1431 from using the memory being corrupted.
1432 However, its intended as a diagnostic tool; if
1433 repeatable BIOS-originated corruption always
1434 affects the same memory, you can use memmap=
1435 to prevent the kernel from using that memory.
1436
1437 memory_corruption_check_size=size [X86]
1438 By default it checks for corruption in the low
1439 64k, making this memory unavailable for normal
1440 use. Use this parameter to scan for
1441 corruption in more or less memory.
1442
1443 memory_corruption_check_period=seconds [X86]
1444 By default it checks for corruption every 60
1445 seconds. Use this parameter to check at some
1446 other rate. 0 disables periodic checking.
1447
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001448 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001449 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001450 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001451 Specifies the number of memtest passes to be
1452 performed. Each pass selects another test
1453 pattern from a given set of patterns. Memtest
1454 fills the memory with this pattern, validates
1455 memory contents and reserves bad memory
1456 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 meye.*= [HW] Set MotionEye Camera parameters
1459 See Documentation/video4linux/meye.txt.
1460
Andres Salomon8f368812007-10-12 23:04:06 +02001461 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1462 Multi-Function General Purpose Timers on AMD Geode
1463 platforms.
1464
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001465 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1466 the BIOS has incorrectly applied a workaround. TinyBIOS
1467 version 0.98 is known to be affected, 0.99 fixes the
1468 problem by letting the user disable the workaround.
1469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 mga= [HW,DRM]
1471
Randy Dunlap1c207f92008-11-19 15:36:16 -08001472 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1473 physical address is ignored.
1474
Michel Pollet39f45d72009-05-20 11:10:31 +01001475 mini2440= [ARM,HW,KNL]
1476 Format:[0..2][b][c][t]
1477 Default: "0tb"
1478 MINI2440 configuration specification:
1479 0 - The attached screen is the 3.5" TFT
1480 1 - The attached screen is the 7" TFT
1481 2 - The VGA Shield is attached (1024x768)
1482 Leaving out the screen size parameter will not load
1483 the TFT driver, and the framebuffer will be left
1484 unconfigured.
1485 b - Enable backlight. The TFT backlight pin will be
1486 linked to the kernel VESA blanking code and a GPIO
1487 LED. This parameter is not necessary when using the
1488 VGA shield.
1489 c - Enable the s3c camera interface.
1490 t - Reserved for enabling touchscreen support. The
1491 touchscreen support is not enabled in the mainstream
1492 kernel as of 2.6.30, a preliminary port can be found
1493 in the "bleeding edge" mini2440 support kernel at
1494 http://repo.or.cz/w/linux-2.6/mini2440.git
1495
Mel Gorman6b74ab92008-07-23 21:26:49 -07001496 mminit_loglevel=
1497 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1498 parameter allows control of the logging verbosity for
1499 the additional memory initialisation checks. A value
1500 of 0 disables mminit logging and a level of 4 will
1501 log everything. Information is printed at KERN_DEBUG
1502 so loglevel=8 may also need to be specified.
1503
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 mousedev.tap_time=
1505 [MOUSE] Maximum time between finger touching and
1506 leaving touchpad surface for touch to be considered
1507 a tap and be reported as a left button click (for
1508 touchpads working in absolute mode only).
1509 Format: <msecs>
1510 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1511 reporting absolute coordinates, such as tablets
1512 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1513 reporting absolute coordinates, such as tablets
1514
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301515 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001516 is similar to kernelcore except it specifies the
1517 amount of memory used for migratable allocations.
1518 If both kernelcore and movablecore is specified,
1519 then kernelcore will be at *least* the specified
1520 value but may be more. If movablecore on its own
1521 is specified, the administrator must be careful
1522 that the amount of memory usable for all allocations
1523 is not too small.
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 mpu401= [HW,OSS]
1526 Format: <io>,<irq>
1527
1528 MTD_Partition= [MTD]
1529 Format: <name>,<region-number>,<size>,<offset>
1530
Randy Dunlapa9913042005-10-23 12:57:11 -07001531 MTD_Region= [MTD] Format:
1532 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
1534 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001535 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001537 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1538
1539 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1540
1541 boundary - index of last SLC block on Flex-OneNAND.
1542 The remaining blocks are configured as MLC blocks.
1543 lock - Configure if Flex-OneNAND boundary should be locked.
1544 Once locked, the boundary cannot be changed.
1545 1 indicates lock status, 0 indicates unlock status.
1546
Ben Dooks9db829f2008-07-03 11:24:29 +01001547 mtdset= [ARM]
1548 ARM/S3C2412 JIVE boot control
1549
1550 See arch/arm/mach-s3c2412/mach-jive.c
1551
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001553 [HW] Make the MicroTouch USB driver use raw coordinates
1554 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001556 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001557 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001558 that could hold holes aka. UC entries.
1559
1560 mtrr_gran_size=nn[KMG] [X86]
1561 Used for mtrr cleanup. It is granularity of mtrr block.
1562 Default is 1.
1563 Large value could prevent small alignment from
1564 using up MTRRs.
1565
1566 mtrr_spare_reg_nr=n [X86]
1567 Format: <integer>
1568 Range: 0,7 : spare reg number
1569 Default : 1
1570 Used for mtrr cleanup. It is spare mtrr entries number.
1571 Set to 2 or more if your graphical card needs more.
1572
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1574
1575 NCR_D700= [HW,SCSI]
1576 See header of drivers/scsi/NCR_D700.c.
1577
1578 ncr5380= [HW,SCSI]
1579
1580 ncr53c400= [HW,SCSI]
1581
1582 ncr53c400a= [HW,SCSI]
1583
1584 ncr53c406a= [HW,SCSI]
1585
1586 ncr53c8xx= [HW,SCSI]
1587
1588 netdev= [NET] Network devices parameters
1589 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1590 Note that mem_start is often overloaded to mean
1591 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001592 This usage is only documented in each driver source
1593 file if at all.
1594
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001595 nf_conntrack.acct=
1596 [NETFILTER] Enable connection tracking flow accounting
1597 0 to disable accounting
1598 1 to enable accounting
1599 Default value depends on CONFIG_NF_CT_ACCT that is
1600 going to be removed in 2.6.29.
1601
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001603 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
1605 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001606 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607
Trond Myklebusta72b4422006-01-03 09:55:41 +01001608 nfs.callback_tcpport=
1609 [NFS] set the TCP port on which the NFSv4 callback
1610 channel should listen.
1611
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001612 nfs.cache_getent=
1613 [NFS] sets the pathname to the program which is used
1614 to update the NFS client cache entries.
1615
1616 nfs.cache_getent_timeout=
1617 [NFS] sets the timeout after which an attempt to
1618 update a cache entry is deemed to have failed.
1619
Trond Myklebust58df0952006-01-03 09:55:57 +01001620 nfs.idmap_cache_timeout=
1621 [NFS] set the maximum lifetime for idmapper cache
1622 entries.
1623
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001624 nfs.enable_ino64=
1625 [NFS] enable 64-bit inode numbers.
1626 If zero, the NFS client will fake up a 32-bit inode
1627 number for the readdir() and stat() syscalls instead
1628 of returning the full 64-bit number.
1629 The default is to return 64-bit inode numbers.
1630
Paul Mundt1e1030d2009-09-01 17:38:32 +09001631 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001632 when a NMI is triggered.
1633 Format: [state][,regs][,debounce][,die]
1634
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301635 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001636 Format: [panic,][num]
1637 Valid num: 0,1,2
1638 0 - turn nmi_watchdog off
1639 1 - use the IO-APIC timer for the NMI watchdog
1640 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001641 a performance counter. Note: This will use one
1642 performance counter and the local APIC's performance
1643 vector.
1644 When panic is specified, panic when an NMI watchdog
1645 timeout occurs.
1646 This is useful when you use a panic=... timeout and
1647 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001648 Instead of 1 and 2 it is possible to use the following
1649 symbolic names: lapic and ioapic
1650 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
Anton Vorontsovbff38772009-07-08 11:10:56 -07001652 netpoll.carrier_timeout=
1653 [NET] Specifies amount of time (in seconds) that
1654 netpoll should wait for a carrier. By default netpoll
1655 waits 4 seconds.
1656
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001657 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 emulation library even if a 387 maths coprocessor
1659 is present.
1660
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001661 no_console_suspend
1662 [HW] Never suspend the console
1663 Disable suspending of consoles during suspend and
1664 hibernate operations. Once disabled, debugging
1665 messages can reach various consoles while the rest
1666 of the system is being put to sleep (ie, while
1667 debugging driver suspend/resume hooks). This may
1668 not work reliably with all consoles, but is known
1669 to work with serial and VGA consoles.
1670
Christoph Lameterc1aee212007-05-31 00:40:47 -07001671 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1672 caches in the slab allocator. Saves per-node memory,
1673 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001674
Randy Dunlapa9913042005-10-23 12:57:11 -07001675 noalign [KNL,ARM]
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677 noapic [SMP,APIC] Tells the kernel to not make use of any
1678 IOAPICs that may be present in the system.
1679
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 nobats [PPC] Do not use BATs for mapping kernel lowmem
1681 on "Classic" PPC cores.
1682
1683 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001684
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001685 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1686
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001687 nodelayacct [KNL] Disable per-task delay accounting
1688
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1690
Paul Mundt6902aa82008-09-21 17:14:42 +09001691 nodsp [SH] Disable hardware DSP at boot time.
1692
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301693 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001694
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 noexec [IA-64]
1696
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301697 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001698 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001700 noexec=off: disable non-executable mappings
1701
1702 noexec32 [X86-64]
1703 This affects only 32-bit executables.
1704 noexec32=on: enable non-executable mappings (default)
1705 read doesn't imply executable mappings
1706 noexec32=off: disable non-executable mappings
1707 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708
Paul Mundt6902aa82008-09-21 17:14:42 +09001709 nofpu [SH] Disable hardware FPU at boot time.
1710
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001711 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001712 register save and restore. The kernel will only save
1713 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714
Suresh Siddha0c752a92009-05-22 12:17:45 -07001715 noxsave [BUGS=X86] Disables x86 extended register state save
1716 and restore using xsave. The kernel will fallback to
1717 enabling legacy floating-point and sse state.
1718
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001719 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1720 wfi(ARM) instruction doesn't work correctly and not to
1721 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001722
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001723 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724 instruction doesn't work correctly and not to
1725 use it.
1726
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001727 no_file_caps Tells the kernel not to honor file capabilities. The
1728 only way then for a file to be executed with privilege
1729 is to be setuid root or executed by root.
1730
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 nohalt [IA-64] Tells the kernel not to use the power saving
1732 function PAL_HALT_LIGHT when idle. This increases
1733 power-consumption. On the positive side, it reduces
1734 interrupt wake-up latency, which may improve performance
1735 in certain environments such as networked servers or
1736 real-time systems.
1737
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001738 nohz= [KNL] Boottime enable/disable dynamic ticks
1739 Valid arguments: on, off
1740 Default: on
1741
Paul Mundteeee7852009-04-02 12:31:16 +09001742 noiotrap [SH] Disables trapped I/O port accesses.
1743
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001744 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 disable unhandled interrupt sources.
1746
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301747 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001748 broken timer IRQ sources.
1749
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 noisapnp [ISAPNP] Disables ISA PnP code.
1751
1752 noinitrd [RAM] Tells the kernel not to load any configured
1753 initial RAM disk.
1754
Weidong Han03ea8152009-04-17 16:42:15 +08001755 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1756 remapping.
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 nointroute [IA-64]
1759
Tony Luck0aa366f2007-07-20 11:22:30 -07001760 nojitter [IA64] Disables jitter checking for ITC timers.
1761
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001762 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001765
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 noltlbs [PPC] Do not use large page/tlb entries for kernel
1767 lowmem mapping on PPC40x.
1768
Horms312f1f02006-02-22 09:57:55 +09001769 nomca [IA-64] Disable machine check abort handling
1770
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001771 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001772
Andres Salomon83d73842007-10-12 23:04:06 +02001773 nomfgpt [X86-32] Disable Multi-Function General Purpose
1774 Timer usage (for AMD Geode machines).
1775
Jiri Kosina016ddd92010-01-18 17:05:40 +01001776 nopat [X86] Disable PAT (page attribute table extension of
1777 pagetables) support.
1778
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001779 norandmaps Don't use address space randomization. Equivalent to
1780 echo 0 > /proc/sys/kernel/randomize_va_space
1781
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001782 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001783
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001784 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001785 with UP alternatives
1786
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 noresidual [PPC] Don't use residual data on PReP machines.
1788
Randy Dunlapa9913042005-10-23 12:57:11 -07001789 noresume [SWSUSP] Disables resume and restores original swap
1790 space.
1791
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 no-scroll [VGA] Disables scrollback.
1793 This is required for the Braillex ib80-piezo Braille
1794 reader made by F.H. Papenmeier (Germany).
1795
1796 nosbagart [IA-64]
1797
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001798 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001799
Len Brown61ec7562007-08-16 03:34:22 -04001800 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1801 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802
Dave Jones97842212007-07-15 23:41:05 -07001803 nosoftlockup [KNL] Disable the soft-lockup detector.
1804
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001805 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001806 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001807
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808 nosync [HW,M68K] Disables sync negotiation for all devices.
1809
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001810 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
1812 nousb [USB] Disable the USB subsystem
1813
1814 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001815
Weidong Han2b2fd872009-04-17 16:42:12 +08001816 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1817
Fenghua Yua6c75b862008-03-14 13:57:08 -07001818 nptcg= [IA64] Override max number of concurrent global TLB
1819 purges which is reported from either PAL_VM_SUMMARY or
1820 SAL PALO.
1821
Yinghai Lu2b633e32010-02-10 01:20:37 -08001822 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1823 could support. nr_cpus=n : n >= 1 limits the kernel to
1824 supporting 'n' processors. Later in runtime you can not
1825 use hotplug cpu feature to put more cpu back to online.
1826 just like you compile the kernel NR_CPUS=n
1827
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001828 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1829
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001830 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1831 one of ['zone', 'node', 'default'] can be specified
1832 This can be set from sysctl after boot.
1833 See Documentation/sysctl/vm.txt for details.
1834
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001835 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1836 See Documentation/debugging-via-ohci1394.txt for more
1837 info.
1838
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001839 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1840 Rather than timing out after 20 ms if an EC
1841 command is not properly ACKed, override the length
1842 of the timeout. We have interrupts disabled while
1843 waiting for the ACK, so if this is set too high
1844 interrupts *may* be lost!
1845
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001846 omap_mux= [OMAP] Override bootloader pin multiplexing.
1847 Format: <mux_mode0.mode_name=value>...
1848 For example, to override I2C bus2:
1849 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1850
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851 opl3= [HW,OSS]
1852 Format: <io>
1853
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 oprofile.timer= [HW]
1855 Use timer interrupt instead of performance counters
1856
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001857 oprofile.cpu_type= Force an oprofile cpu type
1858 This might be useful if you have an older oprofile
1859 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001860 Format: { arch_perfmon }
1861 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001862 perfmon on Intel CPUs instead of the
1863 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001864
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 osst= [HW,SCSI] SCSI Tape Driver
1866 Format: <buffer_size>,<write_threshold>
1867 See also Documentation/scsi/st.txt.
1868
1869 panic= [KNL] Kernel behaviour on panic
1870 Format: <timeout>
1871
1872 parkbd.port= [HW] Parallel port number the keyboard adapter is
1873 connected to, default is 0.
1874 Format: <parport#>
1875 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1876 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001877 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878
Randy Dunlapa9913042005-10-23 12:57:11 -07001879 parport= [HW,PPT] Specify parallel ports. 0 disables.
1880 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1881 Use 'auto' to force the driver to use any
1882 IRQ/DMA settings detected (the default is to
1883 ignore detected IRQ/DMA settings because of
1884 possible conflicts). You can specify the base
1885 address, IRQ, and DMA settings; IRQ and DMA
1886 should be numbers, or 'auto' (for using detected
1887 settings on that particular port), or 'nofifo'
1888 (to avoid using a FIFO even if it is detected).
1889 Parallel ports are assigned in the order they
1890 are specified on the command line, starting
1891 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892
Randy Dunlapa9913042005-10-23 12:57:11 -07001893 parport_init_mode= [HW,PPT]
1894 Configure VIA parallel port to operate in
1895 a specific mode. This is necessary on Pegasos
1896 computer where firmware has no options for setting
1897 up parallel port mode and sets it to spp.
1898 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 Format: [spp|ps2|epp|ecp|ecpepp]
1900
Randy Dunlapa9913042005-10-23 12:57:11 -07001901 pas2= [HW,OSS] Format:
1902 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1903
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904 pas16= [HW,SCSI]
1905 See header of drivers/scsi/pas16.c.
1906
Andrew Mortondd287792006-03-23 03:00:57 -08001907 pause_on_oops=
1908 Halt all CPUs after the first oops has been printed for
1909 the specified number of seconds. This is to be used if
1910 your oopses keep scrolling off the screen.
1911
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 pcbit= [HW,ISDN]
1913
1914 pcd. [PARIDE]
1915 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001916 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917
Randy Dunlapa9913042005-10-23 12:57:11 -07001918 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001919 earlydump [X86] dump PCI config space before the kernel
1920 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001921 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001922 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001923 the hardware directly. Use this if your machine
1924 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001925 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001926 hardware access methods are allowed. Use this
1927 if you experience crashes upon bootup and you
1928 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001929 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001930 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001931 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001932 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001933 noaer [PCIE] If the PCIEAER kernel config parameter is
1934 enabled, this kernel boot option can be used to
1935 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001936 nodomains [PCI] Disable support for multiple PCI
1937 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301938 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001939 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001940 check_enable_amd_mmconf [X86] check for and enable
1941 properly configured MMIO access to PCI
1942 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001943 nomsi [MSI] If the PCI_MSI kernel config parameter is
1944 enabled, this kernel boot option can be used to
1945 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001946 noioapicquirk [APIC] Disable all boot interrupt quirks.
1947 Safety option to keep boot IRQs enabled. This
1948 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001949 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1950 primary IO-APIC for bridges that cannot disable
1951 boot IRQs. This fixes a source of spurious IRQs
1952 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001953 noioapicreroute [APIC] Disable workaround that uses the
1954 boot IRQ equivalent of an IRQ that connects to
1955 a chipset where boot IRQs cannot be disabled.
1956 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001957 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001958 routing table. These calls are known to be buggy
1959 on several machines and they hang the machine
1960 when used, but on other computers it's the only
1961 way to get the interrupt routing table. Try
1962 this option if the kernel is unable to allocate
1963 IRQs or discover secondary PCI buses on your
1964 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001965 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001966 Use with caution as certain devices share
1967 address decoders between ROMs and other
1968 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001969 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001970 expansion ROMs that do not already have
1971 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001972 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001973 assigned automatically to PCI devices. You can
1974 make the kernel exclude IRQs of your ISA cards
1975 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001976 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001977 of the PIRQ table (normally generated
1978 by the BIOS) if it is outside the
1979 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001980 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001981 useful if the kernel is unable to find your
1982 secondary buses and you want to tell it
1983 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001984 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001985 numbers ourselves, overriding
1986 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001987 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001988 in the BIOS $PIR table. This is needed on
1989 some systems with broken BIOSes, notably
1990 some HP Pavilion N5400 and Omnibook XE3
1991 notebooks. This will have no effect if ACPI
1992 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001993 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001994 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001995 use_crs [X86] Use PCI host bridge window information
1996 from ACPI. On BIOSes from 2008 or later, this
1997 is enabled by default. If you need to use this,
1998 please report a bug.
1999 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2000 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002001 routeirq Do IRQ routing for all PCI devices.
2002 This is normally done in pci_enable_device(),
2003 so this option is a temporary workaround
2004 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002005 skip_isa_align [X86] do not align io start addr, so can
2006 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002007 firmware [ARM] Do not re-enumerate the bus but instead
2008 just use the configuration from the
2009 bootloader. This is currently used on
2010 IXP2000 systems where the bus has to be
2011 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002012 noearly [X86] Don't do any early type 1 scanning.
2013 This might help on some broken boards which
2014 machine check when some devices' config space
2015 is read. But various workarounds are disabled
2016 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002017 bfsort Sort PCI devices into breadth-first order.
2018 This sorting is done to get a device
2019 order compatible with older (<= 2.4) kernels.
2020 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002021 cbiosize=nn[KMG] The fixed amount of bus space which is
2022 reserved for the CardBus bridge's IO window.
2023 The default value is 256 bytes.
2024 cbmemsize=nn[KMG] The fixed amount of bus space which is
2025 reserved for the CardBus bridge's memory
2026 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002027 resource_alignment=
2028 Format:
2029 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2030 Specifies alignment and device to reassign
2031 aligned memory resources.
2032 If <order of align> is not specified,
2033 PAGE_SIZE is used as alignment.
2034 PCI-PCI bridge can be specified, if resource
2035 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002036 ecrc= Enable/disable PCIe ECRC (transaction layer
2037 end-to-end CRC checking).
2038 bios: Use BIOS/firmware settings. This is the
2039 the default.
2040 off: Turn ECRC off
2041 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002042
Chuck Ebberte5665a42008-09-24 20:40:34 -04002043 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2044 Management.
2045 off Disable ASPM.
2046 force Enable ASPM even on devices that claim not to support it.
2047 WARNING: Forcing ASPM on may cause system lockups.
2048
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002049 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockib27759f2010-06-18 17:04:22 +02002050 Format: {auto|force}[,nomsi]
2051 auto Use native PCIe PME signaling if the BIOS allows the
2052 kernel to control PCIe config registers of root ports.
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002053 force Use native PCIe PME signaling even if the BIOS refuses
2054 to allow the kernel to control the relevant PCIe config
2055 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002056 nomsi Do not use MSI for native PCIe PME signaling (this makes
2057 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002058
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059 pcmv= [HW,PCMCIA] BadgePAD 4
2060
2061 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002062 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063
2064 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2065 boot time.
2066 Format: { 0 | 1 }
2067 See arch/parisc/kernel/pdc_chassis.c
2068
Tejun Heof58dc012009-08-14 15:00:50 +09002069 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002070 Currently supported values are "embed" and "page".
2071 Archs may support subset or none of the selections.
2072 See comments in mm/percpu.c for details on each
2073 allocator. This parameter is primarily for debugging
2074 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002075
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002077 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078
2079 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002080 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081
2082 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002083 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084
2085 plip= [PPT,NET] Parallel port network link
2086 Format: { parport<nr> | timid | 0 }
2087 See also Documentation/parport.txt.
2088
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002089 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2090 Override pmtimer IOPort with a hex value.
2091 e.g. pmtmr=0x508
2092
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002093 pnp.debug [PNP]
2094 Enable PNP debug messages. This depends on the
2095 CONFIG_PNP_DEBUG_MESSAGES option.
2096
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097 pnpacpi= [ACPI]
2098 { off }
2099
2100 pnpbios= [ISAPNP]
2101 { on | off | curr | res | no-curr | no-res }
2102
2103 pnp_reserve_irq=
2104 [ISAPNP] Exclude IRQs for the autoconfiguration
2105
2106 pnp_reserve_dma=
2107 [ISAPNP] Exclude DMAs for the autoconfiguration
2108
2109 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002110 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111
2112 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002113 [ISAPNP] Exclude memory regions for the
2114 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 Ranges are in pairs (memory base and size).
2116
Randy Dunlap4af94f32009-04-17 18:30:28 -07002117 ports= [IP_VS_FTP] IPVS ftp helper module
2118 Default is 21.
2119 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2120 may be specified.
2121 Format: <port>,<port>....
2122
Ingo Molnar45807a12007-07-15 23:40:10 -07002123 print-fatal-signals=
2124 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002125
2126 If enabled, warn about various signal handling
2127 related application anomalies: too many signals,
2128 too many POSIX.1 timers, fatal signals causing a
2129 coredump - etc.
2130
2131 If you hit the warning due to signal overflow,
2132 you might want to try "ulimit -i unlimited".
2133
Ingo Molnar45807a12007-07-15 23:40:10 -07002134 default: off.
2135
Randy Dunlape84845c2007-07-15 23:40:25 -07002136 printk.time= Show timing data prefixed to each printk message line
2137 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2138
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002139 processor.max_cstate= [HW,ACPI]
2140 Limit processor to maximum C-state
2141 max_cstate=9 overrides any DMI blacklist limit.
2142
2143 processor.nocst [HW,ACPI]
2144 Ignore the _CST method to determine C-states,
2145 instead using the legacy FADT method
2146
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002148 Format: [schedule,]<number>
2149 Param: "schedule" - profile schedule points.
2150 Param: <number> - step/bucket size as a power of 2 for
2151 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002152 Param: "sleep" - profile D-state sleeping (millisecs).
2153 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002154 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2157 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002158 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159
Randy Dunlapa9913042005-10-23 12:57:11 -07002160 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2161 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2163 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002164 psmouse.resetafter= [HW,MOUSE]
2165 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 (0 = never).
2167 psmouse.resolution=
2168 [HW,MOUSE] Set desired mouse resolution, in dpi.
2169 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002170 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171 0 = disabled, 1 = enabled (default).
2172
2173 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002174 Format:
2175 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176
2177 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002178 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179
Kay Sieversdc8c8582007-08-15 12:25:38 +02002180 pty.legacy_count=
2181 [KNL] Number of legacy pty's. Overwrites compiled-in
2182 default number.
2183
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002184 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002185
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 r128= [HW,DRM]
2187
2188 raid= [HW,RAID]
2189 See Documentation/md.txt.
2190
Randy Dunlapa9913042005-10-23 12:57:11 -07002191 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002192 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002193
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002195 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002197 rcupdate.blimit= [KNL,BOOT]
2198 Set maximum number of finished RCU callbacks to process
2199 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002200
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002201 rcupdate.qhimark= [KNL,BOOT]
2202 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002203 RCU callbacks over which batch limiting is disabled.
2204
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002205 rcupdate.qlowmark= [KNL,BOOT]
2206 Set threshold of queued RCU callbacks below which
2207 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002208
Olof Johanssonffdfc402005-09-06 15:17:19 -07002209 rdinit= [KNL]
2210 Format: <full_path>
2211 Run specified binary instead of /init from the ramdisk,
2212 used for early userspace startup. See initrd.
2213
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002214 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002215 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002216 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217
Paul Jackson46b6d942008-07-04 10:00:09 -07002218 relax_domain_level=
2219 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002220 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002221
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2223
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002224 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002225 Format: nn[KMG]
2226 Reserves a hole at the top of the kernel virtual
2227 address space.
2228
Vivek Goyal7e962872006-09-27 01:50:44 -07002229 reset_devices [KNL] Force drivers to reset the underlying device
2230 during initialization.
2231
Randy Dunlapa9913042005-10-23 12:57:11 -07002232 resume= [SWSUSP]
2233 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002235 resume_offset= [SWSUSP]
2236 Specify the offset from the beginning of the partition
2237 given by "resume=" at which the swap header is located,
2238 in <PAGE_SIZE> units (needed only for swap files).
2239 See Documentation/power/swsusp-and-swap-files.txt
2240
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002241 retain_initrd [RAM] Keep initrd memory after extraction
2242
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243 rhash_entries= [KNL,NET]
2244 Set number of hash buckets for route cache
2245
2246 riscom8= [HW,SERIAL]
2247 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2248
2249 ro [KNL] Mount root device read-only on boot
2250
2251 root= [KNL] Root filesystem
2252
2253 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2254 mount the root filesystem
2255
2256 rootflags= [KNL] Set root filesystem mount option string
2257
2258 rootfstype= [KNL] Set root filesystem type
2259
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002260 rootwait [KNL] Wait (indefinitely) for root device to show up.
2261 Useful for devices that are detected asynchronously
2262 (e.g. USB and MMC devices).
2263
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 rw [KNL] Mount root device read-write on boot
2265
2266 S [KNL] Run init in single mode
2267
2268 sa1100ir [NET]
2269 See drivers/net/irda/sa1100_ir.c.
2270
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002272
Mike Travisf6630112009-11-17 18:22:15 -06002273 sched_debug [KNL] Enables verbose scheduler debug messages.
2274
Linus Torvalds1da177e2005-04-16 15:20:36 -07002275 scsi_debug_*= [SCSI]
2276 See drivers/scsi/scsi_debug.c.
2277
2278 scsi_default_dev_flags=
2279 [SCSI] SCSI default device flags
2280 Format: <integer>
2281
2282 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2283 Format: <vendor>:<model>:<flags>
2284 (flags are integer value)
2285
Randy Dunlap6af66322007-11-14 16:52:25 -08002286 scsi_logging_level= [SCSI] a bit mask of logging levels
2287 See drivers/scsi/scsi_logging.h for bits. Also
2288 settable via sysctl at dev.scsi.logging_level
2289 (/proc/sys/dev/scsi/logging_level).
2290 There is also a nice 'scsi_logging_level' script in the
2291 S390-tools package, available for download at
2292 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002293
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002294 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2295 discovered. async scans them in kernel threads,
2296 allowing boot to proceed. none ignores them, expecting
2297 user space to do the scan.
2298
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002299 security= [SECURITY] Choose a security module to enable at boot.
2300 If this boot parameter is not specified, only the first
2301 security module asking for security registration will be
2302 loaded. An invalid security module name will be treated
2303 as if no module has been chosen.
2304
2305 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 Format: { "0" | "1" }
2307 See security/selinux/Kconfig help text.
2308 0 -- disable.
2309 1 -- enable.
2310 Default value is set via kernel config option.
2311 If enabled at boot time, /selinux/disable can be used
2312 later to disable prior to initial policy load.
2313
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002314 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 shapers= [NET]
2317 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002318
Yinghai Lub05f78f2008-08-22 01:32:50 -07002319 show_msr= [x86] show boot-time MSR settings
2320 Format: { <integer> }
2321 Show boot-time (BIOS-initialized) MSR settings.
2322 The parameter means the number of CPUs to show,
2323 for example 1 means boot CPU only.
2324
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 sim710= [SCSI,HW]
2326 See header of drivers/scsi/sim710.c.
2327
2328 simeth= [IA-64]
2329 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002330
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331 slram= [HW,MTD]
2332
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002333 slub_debug[=options[,slabs]] [MM, SLUB]
2334 Enabling slub_debug allows one to determine the
2335 culprit if slab objects become corrupted. Enabling
2336 slub_debug can create guard zones around objects and
2337 may poison objects when not in use. Also tracks the
2338 last alloc / free. For more information see
2339 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002340
2341 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002342 Determines the maximum allowed order for slabs.
2343 A high setting may cause OOMs due to memory
2344 fragmentation. For more information see
2345 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002346
2347 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002348 The minimum number of objects per slab. SLUB will
2349 increase the slab order up to slub_max_order to
2350 generate a sufficiently large slab able to contain
2351 the number of objects indicated. The higher the number
2352 of objects the smaller the overhead of tracking slabs
2353 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002354 For more information see Documentation/vm/slub.txt.
2355
2356 slub_min_order= [MM, SLUB]
2357 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002358 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002359 For more information see Documentation/vm/slub.txt.
2360
2361 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002362 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002363 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002364 allocs to different slabs. Debug options disable
2365 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002366 For more information see Documentation/vm/slub.txt.
2367
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 smart2= [HW]
2369 Format: <io1>[,<io2>[,...,<io8>]]
2370
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002371 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002372 attempt to substitute SMP alternatives once at boot.
2373
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002374 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2375 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2376 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2377 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2378 smsc-ircc2.ircc_irq= [HW] IRQ line
2379 smsc-ircc2.ircc_dma= [HW] DMA channel
2380 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2381 0: Toshiba Satellite 1800 (GP data pin select)
2382 1: Fast pin select (default)
2383 2: ATC IRMode
2384
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385 snd-ad1816a= [HW,ALSA]
2386
2387 snd-ad1848= [HW,ALSA]
2388
2389 snd-ali5451= [HW,ALSA]
2390
2391 snd-als100= [HW,ALSA]
2392
2393 snd-als4000= [HW,ALSA]
2394
2395 snd-azt2320= [HW,ALSA]
2396
2397 snd-cmi8330= [HW,ALSA]
2398
2399 snd-cmipci= [HW,ALSA]
2400
2401 snd-cs4231= [HW,ALSA]
2402
2403 snd-cs4232= [HW,ALSA]
2404
2405 snd-cs4236= [HW,ALSA]
2406
2407 snd-cs4281= [HW,ALSA]
2408
2409 snd-cs46xx= [HW,ALSA]
2410
2411 snd-dt019x= [HW,ALSA]
2412
2413 snd-dummy= [HW,ALSA]
2414
2415 snd-emu10k1= [HW,ALSA]
2416
2417 snd-ens1370= [HW,ALSA]
2418
2419 snd-ens1371= [HW,ALSA]
2420
2421 snd-es968= [HW,ALSA]
2422
2423 snd-es1688= [HW,ALSA]
2424
2425 snd-es18xx= [HW,ALSA]
2426
2427 snd-es1938= [HW,ALSA]
2428
2429 snd-es1968= [HW,ALSA]
2430
2431 snd-fm801= [HW,ALSA]
2432
2433 snd-gusclassic= [HW,ALSA]
2434
2435 snd-gusextreme= [HW,ALSA]
2436
2437 snd-gusmax= [HW,ALSA]
2438
2439 snd-hdsp= [HW,ALSA]
2440
2441 snd-ice1712= [HW,ALSA]
2442
2443 snd-intel8x0= [HW,ALSA]
2444
2445 snd-interwave= [HW,ALSA]
2446
2447 snd-interwave-stb=
2448 [HW,ALSA]
2449
2450 snd-korg1212= [HW,ALSA]
2451
2452 snd-maestro3= [HW,ALSA]
2453
2454 snd-mpu401= [HW,ALSA]
2455
2456 snd-mtpav= [HW,ALSA]
2457
2458 snd-nm256= [HW,ALSA]
2459
2460 snd-opl3sa2= [HW,ALSA]
2461
2462 snd-opti92x-ad1848=
2463 [HW,ALSA]
2464
2465 snd-opti92x-cs4231=
2466 [HW,ALSA]
2467
2468 snd-opti93x= [HW,ALSA]
2469
2470 snd-pmac= [HW,ALSA]
2471
2472 snd-rme32= [HW,ALSA]
2473
2474 snd-rme96= [HW,ALSA]
2475
2476 snd-rme9652= [HW,ALSA]
2477
2478 snd-sb8= [HW,ALSA]
2479
2480 snd-sb16= [HW,ALSA]
2481
2482 snd-sbawe= [HW,ALSA]
2483
2484 snd-serial= [HW,ALSA]
2485
2486 snd-sgalaxy= [HW,ALSA]
2487
2488 snd-sonicvibes= [HW,ALSA]
2489
2490 snd-sun-amd7930=
2491 [HW,ALSA]
2492
2493 snd-sun-cs4231= [HW,ALSA]
2494
2495 snd-trident= [HW,ALSA]
2496
2497 snd-usb-audio= [HW,ALSA,USB]
2498
2499 snd-via82xx= [HW,ALSA]
2500
2501 snd-virmidi= [HW,ALSA]
2502
2503 snd-wavefront= [HW,ALSA]
2504
2505 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002506
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002507 softlockup_panic=
2508 [KNL] Should the soft-lockup detector generate panics.
2509
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2511 See Documentation/sonypi.txt
2512
2513 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002514 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515
2516 spia_io_base= [HW,MTD]
2517 spia_fio_base=
2518 spia_pedr=
2519 spia_peddr=
2520
2521 sscape= [HW,OSS]
2522 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002523
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2525 See Documentation/scsi/st.txt.
2526
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002527 stacktrace [FTRACE]
2528 Enabled the stack tracer on boot up.
2529
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530 sti= [PARISC,HW]
2531 Format: <num>
2532 Set the STI (builtin display/keyboard on the HP-PARISC
2533 machines) console (graphic card) which should be used
2534 as the initial boot-console.
2535 See also comment in drivers/video/console/sticore.c.
2536
2537 sti_font= [HW]
2538 See comment in drivers/video/console/sticore.c.
2539
2540 stifb= [HW]
2541 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2542
Trond Myklebustcbf11072009-08-09 15:06:19 -04002543 sunrpc.min_resvport=
2544 sunrpc.max_resvport=
2545 [NFS,SUNRPC]
2546 SunRPC servers often require that client requests
2547 originate from a privileged port (i.e. a port in the
2548 range 0 < portnr < 1024).
2549 An administrator who wishes to reserve some of these
2550 ports for other uses may adjust the range that the
2551 kernel's sunrpc client considers to be privileged
2552 using these two parameters to set the minimum and
2553 maximum port values.
2554
Greg Banks42a7fc42007-03-06 01:42:23 -08002555 sunrpc.pool_mode=
2556 [NFS]
2557 Control how the NFS server code allocates CPUs to
2558 service thread pools. Depending on how many NICs
2559 you have and where their interrupts are bound, this
2560 option will affect which CPUs will do NFS serving.
2561 Note: this parameter cannot be changed while the
2562 NFS server is running.
2563
2564 auto the server chooses an appropriate mode
2565 automatically using heuristics
2566 global a single global pool contains all CPUs
2567 percpu one pool for each CPU
2568 pernode one pool for each NUMA node (equivalent
2569 to global on non-NUMA machines)
2570
Trond Myklebustcbf11072009-08-09 15:06:19 -04002571 sunrpc.tcp_slot_table_entries=
2572 sunrpc.udp_slot_table_entries=
2573 [NFS,SUNRPC]
2574 Sets the upper limit on the number of simultaneous
2575 RPC calls that can be sent from the client to a
2576 server. Increasing these values may allow you to
2577 improve throughput, but will also increase the
2578 amount of memory reserved for use by the client.
2579
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002581
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 switches= [HW,M68k]
2583
2584 sym53c416= [HW,SCSI]
2585 See header of drivers/scsi/sym53c416.c.
2586
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002587 sysrq_always_enabled
2588 [KNL]
2589 Ignore sysrq setting - this boot parameter will
2590 neutralize any effect of /proc/sys/kernel/sysrq.
2591 Useful for debugging.
2592
Linus Torvalds1da177e2005-04-16 15:20:36 -07002593 t128= [HW,SCSI]
2594 See header of drivers/scsi/t128.c.
2595
2596 tdfx= [HW,DRM]
2597
David Brownell77437fd2008-07-23 21:28:33 -07002598 test_suspend= [SUSPEND]
2599 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2600 standby suspend) as the system sleep state to briefly
2601 enter during system startup. The system is woken from
2602 this state using a wakeup-capable RTC alarm.
2603
Linus Torvalds1da177e2005-04-16 15:20:36 -07002604 thash_entries= [KNL,NET]
2605 Set number of hash buckets for TCP connection
2606
Len Brownf8707ec2007-08-12 00:12:54 -04002607 thermal.act= [HW,ACPI]
2608 -1: disable all active trip points in all thermal zones
2609 <degrees C>: override all lowest active trip points
2610
Len Brownc52a7412007-08-14 15:49:32 -04002611 thermal.crt= [HW,ACPI]
2612 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002613 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002614
Len Brownf5487142007-08-12 00:12:44 -04002615 thermal.nocrt= [HW,ACPI]
2616 Set to disable actions on ACPI thermal zone
2617 critical and hot trip points.
2618
Len Brown72b33ef2007-08-12 00:12:17 -04002619 thermal.off= [HW,ACPI]
2620 1: disable ACPI thermal control
2621
Len Browna70cdc52007-08-12 00:12:35 -04002622 thermal.psv= [HW,ACPI]
2623 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002624 <degrees C>: override all passive trip points to this
2625 value
Len Browna70cdc52007-08-12 00:12:35 -04002626
Len Brown730ff342007-08-12 00:12:26 -04002627 thermal.tzp= [HW,ACPI]
2628 Specify global default ACPI thermal zone polling rate
2629 <deci-seconds>: poll all this frequency
2630 0: no polling (default)
2631
Linus Torvalds1da177e2005-04-16 15:20:36 -07002632 tmscsim= [HW,SCSI]
2633 See comment before function dc390_setup() in
2634 drivers/scsi/tmscsim.c.
2635
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002636 topology= [S390]
2637 Format: {off | on}
2638 Specify if the kernel should make use of the cpu
2639 topology informations if the hardware supports these.
2640 The scheduler will make use of these informations and
2641 e.g. base its process migration decisions on it.
2642 Default is off.
2643
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 tp720= [HW,PS2]
2645
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002646 tpm_suspend_pcr=[HW,TPM]
2647 Format: integer pcr id
2648 Specify that at suspend time, the tpm driver
2649 should extend the specified pcr with zeros,
2650 as a workaround for some chips which fail to
2651 flush the last written pcr on TPM_SaveState.
2652 This will guarantee that all the other pcrs
2653 are saved.
2654
Li Zefan9d612be2009-06-24 17:33:15 +08002655 trace_buf_size=nn[KMG]
2656 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002657
Li Zefan020e5f82009-07-01 10:47:05 +08002658 trace_event=[event-list]
2659 [FTRACE] Set and start specified trace events in order
2660 to facilitate early boot debugging.
2661 See also Documentation/trace/events.txt
2662
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002664 Format:
2665 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2666
Alok Kataria395628e2008-10-24 17:22:01 -07002667 tsc= Disable clocksource-must-verify flag for TSC.
2668 Format: <string>
2669 [x86] reliable: mark tsc clocksource as reliable, this
2670 disables clocksource verification at runtime.
2671 Used to enable high-resolution timer mode on older
2672 hardware, and in virtualized environment.
2673
Randy Dunlapa9913042005-10-23 12:57:11 -07002674 turbografx.map[2|3]= [HW,JOY]
2675 TurboGraFX parallel port interface
2676 Format:
2677 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002678 See also Documentation/input/joystick-parport.txt
2679
2680 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2681 See header of drivers/scsi/u14-34f.c.
2682
2683 uart401= [HW,OSS]
2684 Format: <io>,<irq>
2685
2686 uart6850= [HW,OSS]
2687 Format: <io>,<irq>
2688
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002689 uhash_entries= [KNL,NET]
2690 Set number of hash buckets for UDP/UDP-Lite connections
2691
Alan Stern5f8364b2006-12-05 16:29:55 -05002692 uhci-hcd.ignore_oc=
2693 [USB] Ignore overcurrent events (default N).
2694 Some badly-designed motherboards generate lots of
2695 bogus events, for ports that aren't wired to
2696 anything. Set this parameter to avoid log spamming.
2697 Note that genuine overcurrent events won't be
2698 reported either.
2699
Simon Arlotte3a61b02008-07-19 23:32:54 +01002700 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302701 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002702 Set unknown_nmi_panic=1 early on boot.
2703
Alan Sternb5e795f2007-02-20 15:00:53 -05002704 usbcore.autosuspend=
2705 [USB] The autosuspend time delay (in seconds) used
2706 for newly-detected USB devices (default 2). This
2707 is the time required before an idle device will be
2708 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002709 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002710
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002711 usbcore.usbfs_snoop=
2712 [USB] Set to log all usbfs traffic (default 0 = off).
2713
2714 usbcore.blinkenlights=
2715 [USB] Set to cycle leds on hubs (default 0 = off).
2716
2717 usbcore.old_scheme_first=
2718 [USB] Start with the old device initialization
2719 scheme (default 0 = off).
2720
2721 usbcore.use_both_schemes=
2722 [USB] Try the other device initialization scheme
2723 if the first one fails (default 1 = enabled).
2724
2725 usbcore.initial_descriptor_timeout=
2726 [USB] Specifies timeout for the initial 64-byte
2727 USB_REQ_GET_DESCRIPTOR request in milliseconds
2728 (default 5000 = 5.0 seconds).
2729
Linus Torvalds1da177e2005-04-16 15:20:36 -07002730 usbhid.mousepoll=
2731 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002732
Alan Sternd4f373e2008-11-10 14:07:45 -05002733 usb-storage.delay_use=
2734 [UMS] The delay in seconds before a new device is
2735 scanned for Logical Units (default 5).
2736
2737 usb-storage.quirks=
2738 [UMS] A list of quirks entries to supplement or
2739 override the built-in unusual_devs list. List
2740 entries are separated by commas. Each entry has
2741 the form VID:PID:Flags where VID and PID are Vendor
2742 and Product ID values (4-digit hex numbers) and
2743 Flags is a set of characters, each corresponding
2744 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002745 a = SANE_SENSE (collect more than 18 bytes
2746 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002747 b = BAD_SENSE (don't collect more than 18
2748 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002749 c = FIX_CAPACITY (decrease the reported
2750 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002751 h = CAPACITY_HEURISTICS (decrease the
2752 reported device capacity by one
2753 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002754 i = IGNORE_DEVICE (don't bind to this
2755 device);
2756 l = NOT_LOCKABLE (don't try to lock and
2757 unlock ejectable media);
2758 m = MAX_SECTORS_64 (don't transfer more
2759 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002760 o = CAPACITY_OK (accept the capacity
2761 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002762 r = IGNORE_RESIDUE (the device reports
2763 bogus residue values);
2764 s = SINGLE_LUN (the device has only one
2765 Logical Unit);
2766 w = NO_WP_DETECT (don't test whether the
2767 medium is write-protected).
2768 Example: quirks=0419:aaf5:rl,0421:0433:rc
2769
Ian Campbell14315592010-02-17 10:38:10 +00002770 userpte=
2771 [X86] Flags controlling user PTE allocations.
2772
2773 nohigh = do not allocate PTE pages in
2774 HIGHMEM regardless of setting
2775 of CONFIG_HIGHPTE.
2776
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302777 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002778 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002779 vdso=1: enable VDSO (default)
2780 vdso=0: disable VDSO mapping
2781
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302782 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002783 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2784 vdso32=1: enable 32-bit VDSO (default)
2785 vdso32=0: disable 32-bit VDSO mapping
2786
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002787 vector= [IA-64,SMP]
2788 vector=percpu: enable percpu vector domain
2789
Linus Torvalds1da177e2005-04-16 15:20:36 -07002790 video= [FB] Frame buffer configuration
2791 See Documentation/fb/modedb.txt.
2792
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002793 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002794 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002795 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002796 Use vga=ask for menu.
2797 This is actually a boot loader parameter; the value is
2798 passed to the kernel using a special protocol.
2799
Randy Dunlapa9913042005-10-23 12:57:11 -07002800 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002801 size of <nn>. This can be used to increase the
2802 minimum size (128MB on x86). It can also be used to
2803 decrease the size and leave more room for directly
2804 mapped kernel RAM.
2805
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002806 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2807 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002808
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002809 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2810 Format: <command>
2811
2812 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2813 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002814
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002815 vt.cur_default= [VT] Default cursor shape.
2816 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2817 the parameters of the <Esc>[?A;B;Cc escape sequence;
2818 see VGA-softcursor.txt. Default: 2 = underline.
2819
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002820 vt.default_blu= [VT]
2821 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2822 Change the default blue palette of the console.
2823 This is a 16-member array composed of values
2824 ranging from 0-255.
2825
2826 vt.default_grn= [VT]
2827 Format: <green0>,<green1>,<green2>,...,<green15>
2828 Change the default green palette of the console.
2829 This is a 16-member array composed of values
2830 ranging from 0-255.
2831
2832 vt.default_red= [VT]
2833 Format: <red0>,<red1>,<red2>,...,<red15>
2834 Change the default red palette of the console.
2835 This is a 16-member array composed of values
2836 ranging from 0-255.
2837
2838 vt.default_utf8=
2839 [VT]
2840 Format=<0|1>
2841 Set system-wide default UTF-8 mode for all tty's.
2842 Default is 1, i.e. UTF-8 mode is enabled for all
2843 newly opened terminals.
2844
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002845 vt.global_cursor_default=
2846 [VT]
2847 Format=<-1|0|1>
2848 Set system-wide default for whether a cursor
2849 is shown on new VTs. Default is -1,
2850 i.e. cursors will be created by default unless
2851 overridden by individual drivers. 0 will hide
2852 cursors, 1 will display them.
2853
Linus Torvalds1da177e2005-04-16 15:20:36 -07002854 waveartist= [HW,OSS]
2855 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002856
Linus Torvalds1da177e2005-04-16 15:20:36 -07002857 wd33c93= [HW,SCSI]
2858 See header of drivers/scsi/wd33c93.c.
2859
2860 wd7000= [HW,SCSI]
2861 See header of drivers/scsi/wd7000.c.
2862
Randy Dunlap4724ba572010-05-03 11:42:52 -07002863 watchdog timers [HW,WDT] For information on watchdog timers,
2864 see Documentation/watchdog/watchdog-parameters.txt
2865 or other driver-specific files in the
2866 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002868 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2869 default x2apic cluster mode on platforms
2870 supporting x2apic.
2871
Jacob Panbb24c472009-09-02 07:37:17 -07002872 x86_mrst_timer= [X86-32,APBT]
2873 Choose timer option for x86 Moorestown MID platform.
2874 Two valid options are apbt timer only and lapic timer
2875 plus one apbt timer for broadcast timer.
2876 x86_mrst_timer=apbt_only | lapic_and_apbt
2877
Linus Torvalds1da177e2005-04-16 15:20:36 -07002878 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2879 xd_geo= See header of drivers/block/xd.c.
2880
2881 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002882 Format:
2883 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002884
Randy Dunlapa9913042005-10-23 12:57:11 -07002885______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886
2887TODO:
2888
2889 Add documentation for ALSA options.
2890 Add more DRM drivers.