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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.
John Johansenc1c124e2010-07-29 14:48:09 -070095 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090097 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500102 FTRACE Function tracing enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300103 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500105 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700113 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700116 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100118 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120In addition, the following text indicates that the option:
121
122 BUGS= Relates to possible processor bugs on the said processor.
123 KNL Is a kernel start-up parameter.
124 BOOT Is a boot loader parameter.
125
126Parameters denoted with BOOT are actually interpreted by the boot
127loader, and have no meaning to the kernel directly.
128Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500129need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Karsten Weiss55588702007-02-13 13:26:21 +0100131There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700132See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
135a trailing = on the name of any parameter states that that parameter will
136be entered as an environment variable, whereas its absence indicates that
137it will appear as a kernel argument readable via /proc/cmdline by programs
138running once the system is up.
139
jens m. noedler9c4751f2006-09-29 02:00:27 -0700140The number of kernel parameters is not limited, but the length of the
141complete command line (parameters including spaces etc.) is limited to
142a fixed number of characters. This limit depends on the architecture
143and is between 256 and 4096 characters. It is defined in the file
144./include/asm/setup.h as COMMAND_LINE_SIZE.
145
146
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530147 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800148 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500149 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 force -- enable ACPI if default was off
151 off -- disable ACPI if default was on
152 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700153 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800155 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800156 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Randy Dunlap53471122008-03-12 18:10:51 -0400158 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Len Browna1fdcc02007-03-11 03:26:14 -0400160 acpi_apic_instance= [ACPI, IOAPIC]
161 Format: <int>
162 2: use 2nd APIC table, if available
163 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400164 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400165
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200166 acpi_backlight= [HW,ACPI]
167 acpi_backlight=vendor
168 acpi_backlight=video
169 If set to vendor, prefer vendor specific driver
170 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
171 of the ACPI video.ko driver.
172
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700173 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
174 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700176 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
177 debug output. Bits in debug_layer correspond to a
178 _COMPONENT in an ACPI source file, e.g.,
179 #define _COMPONENT ACPI_PCI_COMPONENT
180 Bits in debug_level correspond to a level in
181 ACPI_DEBUG_PRINT statements, e.g.,
182 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600183 The debug_level mask defaults to "info". See
184 Documentation/acpi/debug.txt for more information about
185 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600187 Enable processor driver info messages:
188 acpi.debug_layer=0x20000000
189 Enable PCI/PCI interrupt routing info messages:
190 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700191 Enable AML "Debug" output, i.e., stores to the Debug
192 object while interpreting AML:
193 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700194 Enable all messages related to ACPI hardware:
195 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200196
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700197 Some values produce so much output that the system is
198 unusable. The "log_buf_len" parameter may be useful
199 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800200
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700201 acpi_display_output= [HW,ACPI]
202 acpi_display_output=vendor
203 acpi_display_output=video
204 See above.
205
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
208 default in APIC mode
209
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
212 default in PIC mode
213
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
216
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 use by PCI
219 Format: <irq>,<irq>...
220
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
222
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
225
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
230
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530231 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
235
Randy Dunlap4af94f32009-04-17 18:30:28 -0700236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
238
239 acpi_serialize [HW,ACPI] force serialization of AML methods
240
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
244
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800247 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700248 See Documentation/power/video.txt for information on
249 s3_bios and s3_mode.
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200258 nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700263
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
267
Luca Tettamanti7e905602009-03-30 00:01:27 +0200268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
283
Randy Dunlap4af94f32009-04-17 18:30:28 -0700284 add_efi_memmap [EFI; X86] Include EFI memory map in
285 kernel's map of available physical RAM.
286
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 advansys= [HW,SCSI]
288 See header of drivers/scsi/advansys.c.
289
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700290 agp= [AGP]
291 { off | try_unsupported }
292 off: disable AGP support
293 try_unsupported: try to drive unsupported chipsets
294 (may crash computer or cause data corruption)
295
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 aha152x= [HW,SCSI]
297 See Documentation/scsi/aha152x.txt.
298
299 aha1542= [HW,SCSI]
300 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
301
302 aic7xxx= [HW,SCSI]
303 See Documentation/scsi/aic7xxx.txt.
304
305 aic79xx= [HW,SCSI]
306 See Documentation/scsi/aic79xx.txt.
307
Randy Dunlapbcfde332010-06-07 17:10:38 -0700308 ALSA [HW,ALSA]
309 See Documentation/sound/alsa/alsa-parameters.txt
310
Russell Kingd944d542010-02-20 16:13:29 +0000311 alignment= [KNL,ARM]
312 Allow the default userspace alignment fault handler
313 behaviour to be specified. Bit 0 enables warnings,
314 bit 1 enables fixups, and bit 2 sends a segfault.
315
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200316 amd_iommu= [HW,X86-84]
317 Pass parameters to the AMD IOMMU driver in the system.
318 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900319 fullflush - enable flushing of IO/TLB entries when
320 they are unmapped. Otherwise they are
321 flushed before they will be reused, which
322 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200323 off - do not initialize any AMD IOMMU found in
324 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900325
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 amijoy.map= [HW,JOY] Amiga joystick support
327 Map of devices attached to JOY0DAT and JOY1DAT
328 Format: <a>,<b>
329 See also Documentation/kernel/input/joystick.txt
330
331 analog.map= [HW,JOY] Analog joystick and gamepad support
332 Specifies type or capabilities of an analog joystick
333 connected to one of 16 gameports
334 Format: <type1>,<type2>,..<type16>
335
Randy Dunlapa9913042005-10-23 12:57:11 -0700336 apc= [HW,SPARC]
337 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 Format: noidle
339 Disable APC CPU standby support. SPARCstation-Fox does
340 not play well with APC CPU idle - disable it if you have
341 APC and your system crashes randomly.
342
Randy Dunlapca1eda22009-05-06 16:02:58 -0700343 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700344 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 Format: { quiet (default) | verbose | debug }
346 Change the amount of debugging information output
347 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700348
Brian Haleyb0f83b22010-02-04 13:36:50 -0800349 autoconf= [IPV6]
350 See Documentation/networking/ipv6.txt.
351
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400352 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
353 Limit apic dumping. The parameter defines the maximal
354 number of local apics being dumped. Also it is possible
355 to set it to "all" by meaning -- no limit here.
356 Format: { 1 (default) | 2 | ... | all }.
357 The parameter valid if only apic=debug or
358 apic=verbose is specified.
359 Example: apic=debug show_lapic=all
360
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700362 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
365 Format: <io>,<irq>,<nodeID>
366
367 ataflop= [HW,M68k]
368
369 atarimouse= [HW,MOUSE] Atari Mouse
370
371 atascsi= [HW,SCSI] Atari SCSI
372
373 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
374 EzKey and similar keyboards
375
376 atkbd.reset= [HW] Reset keyboard during initialization
377
Randy Dunlapa9913042005-10-23 12:57:11 -0700378 atkbd.set= [HW] Select keyboard code set
379 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
381 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
382 keyboards
383
384 atkbd.softraw= [HW] Choose between synthetic and real raw mode
385 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700386
387 atkbd.softrepeat= [HW]
388 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389
390 autotest [IA64]
391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 baycom_epp= [HW,AX25]
393 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
396 Format: <io>,<mode>
397 See header of drivers/net/hamradio/baycom_par.c.
398
Randy Dunlapa9913042005-10-23 12:57:11 -0700399 baycom_ser_fdx= [HW,AX25]
400 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 Format: <io>,<irq>,<mode>[,<baud>]
402 See header of drivers/net/hamradio/baycom_ser_fdx.c.
403
Randy Dunlapa9913042005-10-23 12:57:11 -0700404 baycom_ser_hdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 Format: <io>,<irq>,<mode>
407 See header of drivers/net/hamradio/baycom_ser_hdx.c.
408
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700409 boot_delay= Milliseconds to delay each printk during boot.
410 Values larger than 10 seconds (10000) are changed to
411 no delay (0).
412 Format: integer
413
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700414 bootmem_debug [KNL] Enable bootmem allocator debug messages.
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700417 bttv.radio= Most important insmod options are available as
418 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
420 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
421
422 BusLogic= [HW,SCSI]
423 See drivers/scsi/BusLogic.c, comment before function
424 BusLogic_ParseDriverOptions().
425
426 c101= [NET] Moxa C101 synchronous serial card
427
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700428 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 Sometimes CPU hardware bugs make them report the cache
430 size incorrectly. The kernel will attempt work arounds
431 to fix known problems, but for some CPUs it is not
432 possible to determine what the correct size should be.
433 This option provides an override for these situations.
434
James Morris20510f22007-10-16 23:31:32 -0700435 capability.disable=
436 [SECURITY] Disable capabilities. This would normally
437 be used only if an alternative security model is to be
438 configured. Potentially dangerous and should only be
439 used if you are entirely sure of the consequences.
440
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100441 ccw_timeout_log [S390]
442 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443
Paul Menage8bab8dd2008-04-04 14:29:57 -0700444 cgroup_disable= [KNL] Disable a particular controller
445 Format: {name of the controller(s) to disable}
446 {Currently supported controllers - "memory"}
447
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 checkreqprot [SELINUX] Set initial checkreqprot flag value.
449 Format: { "0" | "1" }
450 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700451 0 -- check protection applied by kernel (includes
452 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 1 -- check protection requested by application.
454 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700455 Value can be changed at runtime via
456 /selinux/checkreqprot.
457
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100458 cio_ignore= [S390]
459 See Documentation/s390/CommonIO for details.
460
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700461 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700462 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200463 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700464 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200465 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 Format: { pit | tsc | cyclone | pmtmr }
467
John Stultz592913e2010-07-13 17:56:20 -0700468 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700469 Format: <string>
470 Override the default clocksource and use the clocksource
471 with the name specified.
472 Some clocksource names to choose from, depending on
473 the platform:
474 [all] jiffies (this is the base, fallback clocksource)
475 [ACPI] acpi_pm
476 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
477 pxa_timer,timer3,32k_counter,timer0_1
478 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700479 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700480 scx200_hrt on Geode; cyclone on IBM x440
481 [MIPS] MIPS
482 [PARISC] cr16
483 [S390] tod
484 [SH] SuperH
485 [SPARC64] tick
486 [X86-64] hpet,tsc
487
Andi Kleenac72e782008-01-30 13:33:21 +0100488 clearcpuid=BITNUM [X86]
489 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800490 arch/x86/include/asm/cpufeature.h for the valid bit
491 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100492 stable over kernel options, but the vendor specific
493 ones should be.
494 Also note that user programs calling CPUID directly
495 or using the feature without checking anything
496 will still see it. This just prevents it from
497 being used by the kernel or shown in /proc/cpuinfo.
498 Also note the kernel might malfunction if you disable
499 some critical bits.
500
Robert Jennings14f966e2009-04-15 05:55:32 +0000501 cmo_free_hint= [PPC] Format: { yes | no }
502 Specify whether pages are marked as being inactive
503 when they are freed. This is used in CMO environments
504 to determine OS memory pressure for page stealing by
505 a hypervisor.
506 Default: yes
507
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530508 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100509 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100510 Range: 0 - 8192
511 Default: 64
512
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700514 Format:
515 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
517 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
518 Format: <io>[,<irq>]
519
Randy Dunlapa9913042005-10-23 12:57:11 -0700520 com90xx= [HW,NET]
521 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 Format: <io>[,<irq>[,<memstart>]]
523
524 condev= [HW,S390] console device
525 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700526
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 console= [KNL] Output console device and options.
528
529 tty<n> Use the virtual console device <n>.
530
531 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800532 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800534 the form "bbbbpnf", where "bbbb" is the baud rate,
535 "p" is parity ("n", "o", or "e"), "n" is number of
536 bits, and "f" is flow control ("r" for RTS or
537 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800539 See Documentation/serial-console.txt for more
540 information. See
541 Documentation/networking/netconsole.txt for an
542 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700544 uart[8250],io,<addr>[,options]
545 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 Start an early, polled-mode console on the 8250/16550
547 UART at the specified I/O port or MMIO address,
548 switching to the matching ttyS device later. The
549 options are the same as for ttyS, above.
550
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700551 If the device connected to the port is not a TTY but a braille
552 device, prepend "brl," before the device type, for instance
553 console=brl,ttyS0
554 For now, only VisioBraille is supported.
555
Daniel Mackf324edc2009-06-16 15:33:52 -0700556 consoleblank= [KNL] The console blank (screen saver) timeout in
557 seconds. Defaults to 10*60 = 10mins. A value of 0
558 disables the blank timer.
559
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800560 coredump_filter=
561 [KNL] Change the default value for
562 /proc/<pid>/coredump_filter.
563 See also Documentation/filesystems/proc.txt.
564
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700566 Format:
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
572
Bernhard Wallefb391592007-10-18 23:41:02 -0700573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
579
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 cs89x0_dma= [HW,NET]
581 Format: <dma>
582
583 cs89x0_media= [HW,NET]
584 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700585
Randy Dunlapa9913042005-10-23 12:57:11 -0700586 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 See header of drivers/s390/block/dasd_devmap.c.
588
589 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
590 (one device per port)
591 Format: <port#>,<type>
592 See also Documentation/input/joystick-parport.txt
593
594 debug [KNL] Enable kernel debugging (events log level).
595
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700596 debug_locks_verbose=
597 [KNL] verbose self-tests
598 Format=<0|1>
599 Print debugging info while doing the locking API
600 self-tests.
601 We default to 0 (no extra messages), setting it to
602 1 will print _a lot_ more information - normally
603 only useful to kernel developers.
604
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700605 debug_objects [KNL] Enable object debugging
606
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500607 no_debug_objects
608 [KNL] Disable object debugging
609
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200610 debugpat [X86] Enable PAT debugging
611
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200612 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 Format: <area>[,<node>]
614 See also Documentation/networking/decnet.txt.
615
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700616 default_hugepagesz=
617 [same as hugepagesz=] The size of the default
618 HugeTLB page size. This is the size represented by
619 the legacy /proc/ hugepages APIs, used for SHM, and
620 default size when mounting hugetlbfs filesystems.
621 Defaults to the default architecture's huge page size
622 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700623
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 dhash_entries= [KNL]
625 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700626
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 digi= [HW,SERIAL]
628 IO parameters + enable/disable command.
629
630 digiepca= [HW,SERIAL]
631 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000632 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633
Brian Haleyb0f83b22010-02-04 13:36:50 -0800634 disable= [IPV6]
635 See Documentation/networking/ipv6.txt.
636
637 disable_ipv6= [IPV6]
638 See Documentation/networking/ipv6.txt.
639
Yinghai Lu95ffa242008-04-29 03:52:33 -0700640 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700641 The kernel tries to adjust MTRR layout from continuous
642 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700643 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700644
Yinghai Lu093af8d2008-01-30 13:33:32 +0100645 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100646 By default the kernel will trim any uncacheable
647 memory out of your available memory pool based on
648 MTRR settings. This parameter disables that behavior,
649 possibly causing your machine to run very slowly.
650
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530651 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700652 Disable PIN 1 of APIC timer
653 Can be useful to work around chipset bugs.
654
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700655 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
656 this option disables the debugging code at boot.
657
658 dma_debug_entries=<number>
659 This option allows to tune the number of preallocated
660 entries for DMA-API debugging code. One entry is
661 required per DMA-API allocation. Use this if the
662 DMA-API debugging code disables itself because the
663 architectural default is too low.
664
Joerg Roedel1745de52009-05-22 21:49:51 +0200665 dma_debug_driver=<driver_name>
666 With this option the DMA-API debugging driver
667 filter feature can be enabled at boot time. Just
668 pass the driver to filter for as the parameter.
669 The filter can be disabled or changed to another
670 driver later using sysfs.
671
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 dscc4.setup= [NET]
673
674 dtc3181e= [HW,SCSI]
675
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700676 dynamic_printk Enables pr_debug()/dev_dbg() calls if
677 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
678 These can also be switched on/off via
679 <debugfs>/dynamic_printk/modules
680
681 earlycon= [KNL] Output early console device and options.
682 uart[8250],io,<addr>[,options]
683 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700684 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700685 Start an early, polled-mode console on the 8250/16550
686 UART at the specified I/O port or MMIO address.
Samium Gromoff1917ac72010-07-20 15:26:51 -0700687 MMIO inter-register address stride is either 8bit (mmio)
688 or 32bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700689 The options are the same as for ttyS, above.
690
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530691 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 earlyprintk=vga
693 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500694 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500695 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696
Randy Dunlapa9913042005-10-23 12:57:11 -0700697 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 takes over.
699
Yinghai Lu5c059172008-07-24 17:29:40 -0700700 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701
702 Currently only ttyS0 and ttyS1 are supported.
703
704 Interaction with the standard serial driver is not
705 very good.
706
707 The VGA output is eventually overwritten by the real
708 console.
709
Jason Wessel97311912010-05-20 21:04:30 -0500710 ekgdboc= [X86,KGDB] Allow early kernel console debugging
711 ekgdboc=kbd
712
713 This is desgined to be used in conjunction with
714 the boot argument: earlyprintk=vga
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 eata= [HW,SCSI]
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700719 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 eisa_irq_edge= [PARISC,HW]
722 See header of drivers/parisc/eisa.c.
723
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700724 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700726 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727
728 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800729 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700730 See Documentation/block/as-iosched.txt and
731 Documentation/block/deadline-iosched.txt for details.
732
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530733 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700734 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800735 image elf header. Generally kexec loader will
736 pass this option to capture kernel.
737 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700739 enable_mtrr_cleanup [X86]
740 The kernel tries to adjust MTRR layout from continuous
741 to discrete, to make X server driver able to add WB
742 entry later. This parameter enables that.
743
Randy Dunlapca1eda22009-05-06 16:02:58 -0700744 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700745 Enable PIN 1 of APIC timer
746 Can be useful to work around chipset bugs
747 (in particular on some ATI chipsets).
748 The kernel tries to set a reasonable default.
749
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 enforcing [SELINUX] Set initial enforcing status.
751 Format: {"0" | "1"}
752 See security/selinux/Kconfig help text.
753 0 -- permissive (log only, no denials).
754 1 -- enforcing (deny and log).
755 Default value is 0.
756 Value can be changed at runtime via /selinux/enforce.
757
Huang Yinga08f82d2010-05-18 14:35:21 +0800758 erst_disable [ACPI]
759 Disable Error Record Serialization Table (ERST)
760 support.
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 ether= [HW,NET] Ethernet cards parameters
763 This option is obsoleted by the "netdev=" option, which
764 has equivalent usage. See its documentation for details.
765
Akinobu Mitade1ba092006-12-08 02:39:42 -0800766 failslab=
767 fail_page_alloc=
768 fail_make_request=[KNL]
769 General fault injection mechanism.
770 Format: <interval>,<probability>,<space>,<times>
771 See also /Documentation/fault-injection/.
772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 fd_mcs= [HW,SCSI]
774 See header of drivers/scsi/fd_mcs.c.
775
776 fdomain= [HW,SCSI]
777 See header of drivers/scsi/fdomain.c.
778
779 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000780 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
Alex Chiangf13ae302008-05-08 14:03:23 -0600782 force_pal_cache_flush
783 [IA-64] Avoid check_sal_cache_flush which may hang on
784 buggy SAL_CACHE_FLUSH implementations. Using this
785 parameter will force ia64_sal_cache_flush to call
786 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
787
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100788 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400789 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100790 as early as possible in order to facilitate early
791 boot debugging.
792
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200793 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400794 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200795 If no parameter is passed, ftrace will dump
796 buffers of all CPUs, but if you pass orig_cpu, it will
797 dump only the buffer of the CPU that triggered the
798 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400799
800 ftrace_filter=[function-list]
801 [FTRACE] Limit the functions traced by the function
802 tracer at boot up. function-list is a comma separated
803 list of functions. This list can be changed at run
804 time by the set_ftrace_filter file in the debugfs
805 tracing directory.
806
807 ftrace_notrace=[function-list]
808 [FTRACE] Do not trace the functions specified in
809 function-list. This list can be changed at run time
810 by the set_ftrace_notrace file in the debugfs
811 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100812
Stefan Assmann369bc182009-10-12 22:17:21 +0200813 ftrace_graph_filter=[function-list]
814 [FTRACE] Limit the top level callers functions traced
815 by the function graph tracer at boot up.
816 function-list is a comma separated list of functions
817 that can be changed at run time by the
818 set_graph_function file in the debugfs tracing directory.
819
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 gamecon.map[2|3]=
821 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
822 support via parallel port (up to 5 devices per port)
823 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
824 See also Documentation/input/joystick-parport.txt
825
826 gamma= [HW,DRM]
827
Yinghai Luaaf23042008-01-30 13:33:09 +0100828 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
829 Format: off | on
830 default: on
831
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700832 gcov_persist= [GCOV] When non-zero (default), profiling data for
833 kernel modules is saved and remains accessible via
834 debugfs, even when the module is unloaded/reloaded.
835 When zero, profiling data is discarded and associated
836 debugfs files are removed at module unload time.
837
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 gdth= [HW,SCSI]
839 See header of drivers/scsi/gdth.c.
840
841 gpt [EFI] Forces disk with valid GPT signature but
842 invalid Protective MBR to be treated as GPT.
843
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 gvp11= [HW,SCSI]
845
846 hashdist= [KNL,NUMA] Large hashes allocated during boot
847 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700848 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700849 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
851 hcl= [IA-64] SGI's Hardware Graph compatibility layer
852
853 hd= [EIDE] (E)IDE hard drive subsystem geometry
854 Format: <cyl>,<head>,<sect>
855
Huang Yingea8c0712010-05-18 14:35:15 +0800856 hest_disable [ACPI]
857 Disable Hardware Error Source Table (HEST) support;
858 corresponding firmware-first mode error processing
859 logic will be disabled.
860
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
862 size of <nn>. This works even on boxes that have no
863 highmem otherwise. This also works to reduce highmem
864 size on bigger boxes.
865
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800866 highres= [KNL] Enable/disable high resolution timer mode.
867 Valid parameters: "on", "off"
868 Default: "on"
869
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 hisax= [HW,ISDN]
871 See Documentation/isdn/README.HiSax.
872
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700873 hlt [BUGS=ARM,SH]
874
875 hpet= [X86-32,HPET] option to control HPET usage
876 Format: { enable (default) | disable | force |
877 verbose }
878 disable: disable HPET and use PIT instead
879 force: allow force enabled of undocumented chips (ICH4,
880 VIA, nVidia)
881 verbose: show contents of HPET registers during setup
882
Andi Kleenb4718e62008-07-23 21:27:51 -0700883 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
884 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700885 On x86-64 and powerpc, this option can be specified
886 multiple times interleaved with hugepages= to reserve
887 huge pages of different sizes. Valid pages sizes on
888 x86-64 are 2M (when the CPU supports "pse") and 1G
889 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700890 Note that 1GB pages can only be allocated at boot time
891 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900892
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100893 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
894 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100895 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
896 If specified, z/VM IUCV HVC accepts connections
897 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100898
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700899 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700900 or register an additional I2C bus that is not
901 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700902 Format:
903 <bus_id>,<clkrate>
904
Jiri Kosina36d95732008-10-06 02:51:09 -0400905 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200907 i8042.dumbkbd [HW] Pretend that controller can only read data from
908 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 (Don't attempt to blink the leds)
910 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500911 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400912 i8042.noloop [HW] Disable the AUX Loopback command while probing
913 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 i8042.nomux [HW] Don't check presence of an active multiplexing
915 controller
916 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
917 controllers
918 i8042.panicblink=
919 [HW] Frequency with which keyboard LEDs should blink
920 when kernel panics (default is 0.5 sec)
921 i8042.reset [HW] Reset the controller during init and cleanup
922 i8042.unlock [HW] Unlock (ignore) the keylock
923
924 i810= [HW,DRM]
925
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700926 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
927 indicates that the driver is running on unsupported
928 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
930 does not match list of supported models.
931 i8k.power_status
932 [HW] Report power status in /proc/i8k
933 (disabled by default)
934 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
935 capability is set.
936
937 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
938 See Documentation/mca.txt.
939
940 icn= [HW,ISDN]
941 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
942
David Fries0af80c02009-02-25 20:28:21 +0100943 ide-core.nodma= [HW] (E)IDE subsystem
944 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200945 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
946 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100947 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700949 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
950 Claim all unknown PCI IDE storage controllers.
951
Andi Kleenf039b752007-05-02 19:27:12 +0200952 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800953 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
954 Poll forces a polling idle loop that can slightly
955 improve the performance of waking up a idle CPU, but
956 will use a lot of power and make the system run hot.
957 Not recommended.
958 idle=mwait: On systems which support MONITOR/MWAIT but
959 the kernel chose to not use it because it doesn't save
960 as much power as a normal idle loop, use the
961 MONITOR/MWAIT idle loop anyways. Performance should be
962 the same as idle=poll.
963 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800964 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800965 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700966
Ingo Molnar792908222006-12-06 20:40:51 -0800967 ignore_loglevel [KNL]
968 Ignore loglevel setting - this will print /all/
969 kernel messages to the console. Useful for debugging.
970
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 ihash_entries= [KNL]
972 Set number of hash buckets for inode cache.
973
Mimi Zohar3323eec2009-02-04 09:06:58 -0500974 ima_audit= [IMA]
975 Format: { "0" | "1" }
976 0 -- integrity auditing messages. (Default)
977 1 -- enable informational integrity auditing messages.
978
979 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700980 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500981 default: "sha1"
982
Eric Paris5789ba32009-05-21 15:47:06 -0400983 ima_tcb [IMA]
984 Load a policy which meets the needs of the Trusted
985 Computing Base. This means IMA will measure all
986 programs exec'd, files mmap'd for exec, and all files
987 opened for read by uid=0.
988
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 in2000= [HW,SCSI]
990 See header of drivers/scsi/in2000.c.
991
992 init= [KNL]
993 Format: <full_path>
994 Run specified binary instead of /sbin/init as init
995 process.
996
997 initcall_debug [KNL] Trace initcalls as they are executed. Useful
998 for working out where the kernel is dying during
999 startup.
1000
1001 initrd= [BOOT] Specify the location of the initial ramdisk
1002
1003 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1004 Format: <irq>
1005
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001006 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001007 on
1008 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001009 off
1010 Disable intel iommu driver.
1011 igfx_off [Default Off]
1012 By default, gfx is mapped as normal device. If a gfx
1013 device has a dedicated DMAR unit, the DMAR unit is
1014 bypassed by not enabling DMAR with this option. In
1015 this case, gfx device will use physical address for
1016 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001017 forcedac [x86_64]
1018 With this option iommu will not optimize to look
1019 for io virtual address below 32 bit forcing dual
1020 address cycle on pci bus for cards supporting greater
1021 than 32 bit addressing. The default is to look
1022 for translation below 32 bit and if not available
1023 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001024 strict [Default Off]
1025 With this option on every unmap_single operation will
1026 result in a hardware IOTLB flush operation as opposed
1027 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001028
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001029 inttest= [IA64]
1030
1031 iomem= Disable strict checking of access to MMIO memory
1032 strict regions from userspace.
1033 relaxed
1034
1035 iommu= [x86]
1036 off
1037 force
1038 noforce
1039 biomerge
1040 panic
1041 nopanic
1042 merge
1043 nomerge
1044 forcesac
1045 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001046 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001047
1048 io7= [HW] IO7 for Marvel based alpha systems
1049 See comment before marvel_specify_io7 in
1050 arch/alpha/kernel/core_marvel.c.
1051
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301052 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001053 0x80
1054 Standard port 0x80 based delay
1055 0xed
1056 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001057 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001058 Simple two microseconds delay
1059 none
1060 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001061
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001063 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
1065 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001066 See comment before ip2_setup() in
1067 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068
1069 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1070 See header of drivers/scsi/ips.c.
1071
Alan Cox200803d2005-06-28 20:45:18 -07001072 irqfixup [HW]
1073 When an interrupt is not handled search all handlers
1074 for it. Intended to get systems with badly broken
1075 firmware running.
1076
1077 irqpoll [HW]
1078 When an interrupt is not handled search all handlers
1079 for it. Also check all handlers each timer
1080 interrupt. Intended to get systems with badly broken
1081 firmware running.
1082
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001084 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
1086 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001087 Format:
1088 <cpu number>,...,<cpu number>
1089 or
Li Zefanb225d442008-11-06 12:53:39 -08001090 <cpu number>-<cpu number>
1091 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001092 or a mixture
1093 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001094
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 This option can be used to specify one or more CPUs
1096 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001097 algorithms. You can move a process onto or off an
1098 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 <cpu number> begins at 0 and the maximum value is
1100 "number of CPUs in system - 1".
1101
1102 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001103 alternative -- manually setting the CPU mask of all
1104 tasks in the system -- can cause problems and
1105 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106
Randy Dunlapa9913042005-10-23 12:57:11 -07001107 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
1109 js= [HW,JOY] Analog joystick
1110 See Documentation/input/joystick.txt.
1111
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001112 keepinitrd [HW,ARM]
1113
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301114 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001115 specifies the amount of memory usable by the kernel
1116 for non-movable allocations. The requested amount is
1117 spread evenly throughout all nodes in the system. The
1118 remaining memory in each node is used for Movable
1119 pages. In the event, a node is too small to have both
1120 kernelcore and Movable pages, kernelcore pages will
1121 take priority and other nodes will have a larger number
1122 of kernelcore pages. The Movable zone is used for the
1123 allocation of pages that may be reclaimed or moved
1124 by the page migration subsystem. This means that
1125 HugeTLB pages may not be allocated from this zone.
1126 Note that allocations like PTEs-from-HighMem still
1127 use the HighMem zone if it exists, and the Normal
1128 zone if it does not.
1129
Jason Wessel4fe1da42010-05-20 21:04:31 -05001130 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1131 Format: <Controller#>[,poll interval]
1132 The controller # is the number of the ehci usb debug
1133 port as it is probed via PCI. The poll interval is
1134 optional and is the number seconds in between
1135 each poll cycle to the debug port in case you need
1136 the functionality for interrupting the kernel with
1137 gdb or control-c on the dbgp connection. When
1138 not using this parameter you use sysrq-g to break into
1139 the kernel debugger.
1140
Jason Wessel84c08fd2010-05-20 21:04:24 -05001141 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001142 Requires a tty driver that supports console polling,
1143 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001144 Serial only format: <serial_device>[,baud]
1145 keyboard only format: kbd
1146 keyboard and serial format: kbd,<serial_device>[,baud]
1147 Optional Kernel mode setting:
1148 kms, kbd format: kms,kbd
1149 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001150
Jason Wessel84c08fd2010-05-20 21:04:24 -05001151 kgdbwait [KGDB] Stop kernel execution and enter the
1152 kernel debugger at the earliest opportunity.
1153
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001154 kmac= [MIPS] korina ethernet MAC address.
1155 Configure the RouterBoard 532 series on-chip
1156 Ethernet adapter MAC address.
1157
Catalin Marinas04f70332009-06-11 13:22:39 +01001158 kmemleak= [KNL] Boot-time kmemleak enable/disable
1159 Valid arguments: on, off
1160 Default: on
1161
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301162 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001163 in oops dumps.
1164
Andre Przywarafef07aa2009-07-10 14:20:35 +02001165 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1166 Default is 0 (don't ignore, but inject #GP)
1167
1168 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1169 Default is 1 (enabled)
1170
1171 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1172 Default is 0 (off)
1173
1174 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1175 for all guests.
1176 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1177
1178 kvm-intel.bypass_guest_pf=
1179 [KVM,Intel] Disables bypassing of guest page faults
1180 on Intel chips. Default is 1 (enabled)
1181
1182 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1183 (virtualized MMU) support on capable Intel chips.
1184 Default is 1 (enabled)
1185
1186 kvm-intel.emulate_invalid_guest_state=
1187 [KVM,Intel] Enable emulation of invalid guest states
1188 Default is 0 (disabled)
1189
1190 kvm-intel.flexpriority=
1191 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1192 Default is 1 (enabled)
1193
1194 kvm-intel.unrestricted_guest=
1195 [KVM,Intel] Disable unrestricted guest feature
1196 (virtualized real and unpaged mode) on capable
1197 Intel chips. Default is 1 (enabled)
1198
1199 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1200 feature (tagged TLBs) on capable Intel chips.
1201 Default is 1 (enabled)
1202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203 l2cr= [PPC]
1204
Robert Brosea78bfbf2008-03-29 07:20:23 +11001205 l3cr= [PPC]
1206
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001207 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001208 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301210 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001211 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001212
FD Camifcb71f62008-01-06 19:08:56 +01001213 libata.dma= [LIBATA] DMA control
1214 libata.dma=0 Disable all PATA and SATA DMA
1215 libata.dma=1 PATA and SATA Disk DMA only
1216 libata.dma=2 ATAPI (CDROM) DMA only
1217 libata.dma=4 Compact Flash DMA only
1218 Combinations also work, so libata.dma=3 enables DMA
1219 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001220
1221 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1222 libata.ignore_hpa=0 keep BIOS limits (default)
1223 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001224
Dave Jones78e70c22007-09-27 11:50:13 -04001225 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1226 when set.
1227 Format: <int>
1228
Tejun Heo33267322008-02-13 09:15:09 +09001229 libata.force= [LIBATA] Force configurations. The format is comma
1230 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001231 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001232 matching port, link or device. Basically, it matches
1233 the ATA ID string printed on console by libata. If
1234 the whole ID part is omitted, the last PORT and DEVICE
1235 values are used. If ID hasn't been specified yet, the
1236 configuration applies to all ports, links and devices.
1237
1238 If only DEVICE is omitted, the parameter applies to
1239 the port and all links and devices behind it. DEVICE
1240 number of 0 either selects the first device or the
1241 first fan-out link behind PMP device. It does not
1242 select the host link. DEVICE number of 15 selects the
1243 host link and device attached to it.
1244
1245 The VAL specifies the configuration to force. As long
1246 as there's no ambiguity shortcut notation is allowed.
1247 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1248 The following configurations can be forced.
1249
1250 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1251 Any ID with matching PORT is used.
1252
1253 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1254
1255 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1256 udma[/][16,25,33,44,66,100,133] notation is also
1257 allowed.
1258
1259 * [no]ncq: Turn on or off NCQ.
1260
Tejun Heo05944bd2008-08-13 20:19:09 +09001261 * nohrst, nosrst, norst: suppress hard, soft
1262 and both resets.
1263
Tejun Heo43c9c592010-05-23 12:59:11 +02001264 * dump_id: dump IDENTIFY data.
1265
Tejun Heo33267322008-02-13 09:15:09 +09001266 If there are multiple matching configurations changing
1267 the same attribute, the last one is used.
1268
Yinghai Lu95f72d12010-07-12 14:36:09 +10001269 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001270
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001272 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001274 lockd.nlm_grace_period=P [NFS] Assign grace period.
1275 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001277 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1278 Format: <integer>
1279
1280 lockd.nlm_timeout=T [NFS] Assign timeout value.
1281 Format: <integer>
1282
1283 lockd.nlm_udpport=M [NFS] Assign UDP port.
1284 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
1286 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1287 Format: <irq>
1288
1289 loglevel= All Kernel Messages with a loglevel smaller than the
1290 console loglevel will be printed to the console. It can
1291 also be changed with klogd or other programs. The
1292 loglevels are defined as follows:
1293
1294 0 (KERN_EMERG) system is unusable
1295 1 (KERN_ALERT) action must be taken immediately
1296 2 (KERN_CRIT) critical conditions
1297 3 (KERN_ERR) error conditions
1298 4 (KERN_WARNING) warning conditions
1299 5 (KERN_NOTICE) normal but significant condition
1300 6 (KERN_INFO) informational
1301 7 (KERN_DEBUG) debug-level messages
1302
1303 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001304 Format: { n | nk | nM }
1305 n must be a power of two. The default size
1306 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307
Randy Dunlapaccaa242007-10-16 01:29:37 -07001308 logo.nologo [FB] Disables display of the built-in Linux logo.
1309 This may be used to provide more screen space for
1310 kernel log messages and is useful when debugging
1311 kernel boot problems.
1312
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 lp=0 [LP] Specify parallel ports to use, e.g,
1314 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1315 lp=reset first parallel port). 'lp=0' disables the
1316 lp=auto printer driver. 'lp=reset' (which can be
1317 specified in addition to the ports) causes
1318 attached printers to be reset. Using
1319 lp=port1,port2,... specifies the parallel ports
1320 to associate lp devices with, starting with
1321 lp0. A port specification may be 'none' to skip
1322 that lp device, or a parport name such as
1323 'parport0'. Specifying 'lp=auto' instead of a
1324 port specification list means that device IDs
1325 from each port should be examined, to see if
1326 an IEEE 1284-compliant printer is attached; if
1327 so, the driver will manage that printer.
1328 See also header of drivers/char/lp.c.
1329
1330 lpj=n [KNL]
1331 Sets loops_per_jiffy to given constant, thus avoiding
1332 time-consuming boot-time autodetection (up to 250 ms per
1333 CPU). 0 enables autodetection (default). To determine
1334 the correct value for your kernel, boot with normal
1335 autodetection and see what value is printed. Note that
1336 on SMP systems the preset will be applied to all CPUs,
1337 which is likely to cause problems if your CPUs need
1338 significantly divergent settings. An incorrect value
1339 will cause delays in the kernel to be wrong, leading to
1340 unpredictable I/O errors and other breakage. Although
1341 unlikely, in the extreme case this might damage your
1342 hardware.
1343
1344 ltpc= [NET]
1345 Format: <io>,<irq>,<dma>
1346
Randy Dunlapa9913042005-10-23 12:57:11 -07001347 mac5380= [HW,SCSI] Format:
1348 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
Randy Dunlapa9913042005-10-23 12:57:11 -07001350 machvec= [IA64] Force the use of a particular machine-vector
1351 (machvec) in a generic kernel.
1352 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
Wu Zhangjin3209e702009-07-02 23:27:12 +08001354 machtype= [Loongson] Share the same kernel image file between different
1355 yeeloong laptop.
1356 Example: machtype=lemote-yeeloong-2f-7inch
1357
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001358 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1359 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360
1361 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001362 should make use of. maxcpus=n : n >= 0 limits the
1363 kernel to using 'n' processors. n=0 is a special case,
1364 it is equivalent to "nosmp", which also disables
1365 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001367 max_loop= [LOOP] Maximum number of loopback devices that can
1368 be mounted
1369 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001370
Randy Dunlapa9913042005-10-23 12:57:11 -07001371 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 Should be between 1 and 2^32-1.
1373
1374 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001375 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 Should be between 1 and 16384.
1377
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 mcatest= [IA-64]
1379
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001380 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381
Uwe Hermann71cced62008-10-20 09:32:21 -07001382 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001383
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 md= [HW] RAID subsystems devices and level
1385 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001386
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 mdacon= [MDA]
1388 Format: <first>,<last>
1389 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001390
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1392 Amount of memory to be used when the kernel is not able
1393 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001394 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 address space collisions. Without memmap= PCI devices
1396 could be placed at addresses belonging to unused RAM.
1397
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001398 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 memory.
1400
Paul Mundt6902aa82008-09-21 17:14:42 +09001401 memchunk=nn[KMG]
1402 [KNL,SH] Allow user to override the default size for
1403 per-device physically contiguous DMA buffers.
1404
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301405 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 E820 memory map, as specified by the user.
1407 Such memmap=exactmap lines can be constructed based on
1408 BIOS output or other requirements. See the memmap=nn@ss
1409 option description.
1410
1411 memmap=nn[KMG]@ss[KMG]
1412 [KNL] Force usage of a specific region of memory
1413 Region of memory to be used, from ss to ss+nn.
1414
1415 memmap=nn[KMG]#ss[KMG]
1416 [KNL,ACPI] Mark specific memory as ACPI data.
1417 Region of memory to be used, from ss to ss+nn.
1418
1419 memmap=nn[KMG]$ss[KMG]
1420 [KNL,ACPI] Mark specific memory as reserved.
1421 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001422 Example: Exclude memory from 0x18690000-0x1869ffff
1423 memmap=64K$0x18690000
1424 or
1425 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001427 memory_corruption_check=0/1 [X86]
1428 Some BIOSes seem to corrupt the first 64k of
1429 memory when doing things like suspend/resume.
1430 Setting this option will scan the memory
1431 looking for corruption. Enabling this will
1432 both detect corruption and prevent the kernel
1433 from using the memory being corrupted.
1434 However, its intended as a diagnostic tool; if
1435 repeatable BIOS-originated corruption always
1436 affects the same memory, you can use memmap=
1437 to prevent the kernel from using that memory.
1438
1439 memory_corruption_check_size=size [X86]
1440 By default it checks for corruption in the low
1441 64k, making this memory unavailable for normal
1442 use. Use this parameter to scan for
1443 corruption in more or less memory.
1444
1445 memory_corruption_check_period=seconds [X86]
1446 By default it checks for corruption every 60
1447 seconds. Use this parameter to check at some
1448 other rate. 0 disables periodic checking.
1449
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001450 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001451 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001452 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001453 Specifies the number of memtest passes to be
1454 performed. Each pass selects another test
1455 pattern from a given set of patterns. Memtest
1456 fills the memory with this pattern, validates
1457 memory contents and reserves bad memory
1458 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 meye.*= [HW] Set MotionEye Camera parameters
1461 See Documentation/video4linux/meye.txt.
1462
Andres Salomon8f368812007-10-12 23:04:06 +02001463 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1464 Multi-Function General Purpose Timers on AMD Geode
1465 platforms.
1466
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001467 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1468 the BIOS has incorrectly applied a workaround. TinyBIOS
1469 version 0.98 is known to be affected, 0.99 fixes the
1470 problem by letting the user disable the workaround.
1471
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 mga= [HW,DRM]
1473
Randy Dunlap1c207f92008-11-19 15:36:16 -08001474 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1475 physical address is ignored.
1476
Michel Pollet39f45d72009-05-20 11:10:31 +01001477 mini2440= [ARM,HW,KNL]
1478 Format:[0..2][b][c][t]
1479 Default: "0tb"
1480 MINI2440 configuration specification:
1481 0 - The attached screen is the 3.5" TFT
1482 1 - The attached screen is the 7" TFT
1483 2 - The VGA Shield is attached (1024x768)
1484 Leaving out the screen size parameter will not load
1485 the TFT driver, and the framebuffer will be left
1486 unconfigured.
1487 b - Enable backlight. The TFT backlight pin will be
1488 linked to the kernel VESA blanking code and a GPIO
1489 LED. This parameter is not necessary when using the
1490 VGA shield.
1491 c - Enable the s3c camera interface.
1492 t - Reserved for enabling touchscreen support. The
1493 touchscreen support is not enabled in the mainstream
1494 kernel as of 2.6.30, a preliminary port can be found
1495 in the "bleeding edge" mini2440 support kernel at
1496 http://repo.or.cz/w/linux-2.6/mini2440.git
1497
Mel Gorman6b74ab92008-07-23 21:26:49 -07001498 mminit_loglevel=
1499 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1500 parameter allows control of the logging verbosity for
1501 the additional memory initialisation checks. A value
1502 of 0 disables mminit logging and a level of 4 will
1503 log everything. Information is printed at KERN_DEBUG
1504 so loglevel=8 may also need to be specified.
1505
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506 mousedev.tap_time=
1507 [MOUSE] Maximum time between finger touching and
1508 leaving touchpad surface for touch to be considered
1509 a tap and be reported as a left button click (for
1510 touchpads working in absolute mode only).
1511 Format: <msecs>
1512 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1513 reporting absolute coordinates, such as tablets
1514 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1515 reporting absolute coordinates, such as tablets
1516
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301517 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001518 is similar to kernelcore except it specifies the
1519 amount of memory used for migratable allocations.
1520 If both kernelcore and movablecore is specified,
1521 then kernelcore will be at *least* the specified
1522 value but may be more. If movablecore on its own
1523 is specified, the administrator must be careful
1524 that the amount of memory usable for all allocations
1525 is not too small.
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 MTD_Partition= [MTD]
1528 Format: <name>,<region-number>,<size>,<offset>
1529
Randy Dunlapa9913042005-10-23 12:57:11 -07001530 MTD_Region= [MTD] Format:
1531 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532
1533 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001534 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001536 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1537
1538 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1539
1540 boundary - index of last SLC block on Flex-OneNAND.
1541 The remaining blocks are configured as MLC blocks.
1542 lock - Configure if Flex-OneNAND boundary should be locked.
1543 Once locked, the boundary cannot be changed.
1544 1 indicates lock status, 0 indicates unlock status.
1545
Ben Dooks9db829f2008-07-03 11:24:29 +01001546 mtdset= [ARM]
1547 ARM/S3C2412 JIVE boot control
1548
1549 See arch/arm/mach-s3c2412/mach-jive.c
1550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001552 [HW] Make the MicroTouch USB driver use raw coordinates
1553 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001555 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001556 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001557 that could hold holes aka. UC entries.
1558
1559 mtrr_gran_size=nn[KMG] [X86]
1560 Used for mtrr cleanup. It is granularity of mtrr block.
1561 Default is 1.
1562 Large value could prevent small alignment from
1563 using up MTRRs.
1564
1565 mtrr_spare_reg_nr=n [X86]
1566 Format: <integer>
1567 Range: 0,7 : spare reg number
1568 Default : 1
1569 Used for mtrr cleanup. It is spare mtrr entries number.
1570 Set to 2 or more if your graphical card needs more.
1571
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1573
1574 NCR_D700= [HW,SCSI]
1575 See header of drivers/scsi/NCR_D700.c.
1576
1577 ncr5380= [HW,SCSI]
1578
1579 ncr53c400= [HW,SCSI]
1580
1581 ncr53c400a= [HW,SCSI]
1582
1583 ncr53c406a= [HW,SCSI]
1584
1585 ncr53c8xx= [HW,SCSI]
1586
1587 netdev= [NET] Network devices parameters
1588 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1589 Note that mem_start is often overloaded to mean
1590 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001591 This usage is only documented in each driver source
1592 file if at all.
1593
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001594 nf_conntrack.acct=
1595 [NETFILTER] Enable connection tracking flow accounting
1596 0 to disable accounting
1597 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001598 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001599
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001601 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
1603 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001604 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605
Trond Myklebusta72b4422006-01-03 09:55:41 +01001606 nfs.callback_tcpport=
1607 [NFS] set the TCP port on which the NFSv4 callback
1608 channel should listen.
1609
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001610 nfs.cache_getent=
1611 [NFS] sets the pathname to the program which is used
1612 to update the NFS client cache entries.
1613
1614 nfs.cache_getent_timeout=
1615 [NFS] sets the timeout after which an attempt to
1616 update a cache entry is deemed to have failed.
1617
Trond Myklebust58df0952006-01-03 09:55:57 +01001618 nfs.idmap_cache_timeout=
1619 [NFS] set the maximum lifetime for idmapper cache
1620 entries.
1621
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001622 nfs.enable_ino64=
1623 [NFS] enable 64-bit inode numbers.
1624 If zero, the NFS client will fake up a 32-bit inode
1625 number for the readdir() and stat() syscalls instead
1626 of returning the full 64-bit number.
1627 The default is to return 64-bit inode numbers.
1628
Paul Mundt1e1030d2009-09-01 17:38:32 +09001629 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001630 when a NMI is triggered.
1631 Format: [state][,regs][,debounce][,die]
1632
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301633 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001634 Format: [panic,][num]
1635 Valid num: 0,1,2
1636 0 - turn nmi_watchdog off
1637 1 - use the IO-APIC timer for the NMI watchdog
1638 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001639 a performance counter. Note: This will use one
1640 performance counter and the local APIC's performance
1641 vector.
1642 When panic is specified, panic when an NMI watchdog
1643 timeout occurs.
1644 This is useful when you use a panic=... timeout and
1645 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001646 Instead of 1 and 2 it is possible to use the following
1647 symbolic names: lapic and ioapic
1648 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649
Anton Vorontsovbff38772009-07-08 11:10:56 -07001650 netpoll.carrier_timeout=
1651 [NET] Specifies amount of time (in seconds) that
1652 netpoll should wait for a carrier. By default netpoll
1653 waits 4 seconds.
1654
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001655 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656 emulation library even if a 387 maths coprocessor
1657 is present.
1658
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001659 no_console_suspend
1660 [HW] Never suspend the console
1661 Disable suspending of consoles during suspend and
1662 hibernate operations. Once disabled, debugging
1663 messages can reach various consoles while the rest
1664 of the system is being put to sleep (ie, while
1665 debugging driver suspend/resume hooks). This may
1666 not work reliably with all consoles, but is known
1667 to work with serial and VGA consoles.
1668
Christoph Lameterc1aee212007-05-31 00:40:47 -07001669 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1670 caches in the slab allocator. Saves per-node memory,
1671 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001672
Randy Dunlapa9913042005-10-23 12:57:11 -07001673 noalign [KNL,ARM]
1674
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 noapic [SMP,APIC] Tells the kernel to not make use of any
1676 IOAPICs that may be present in the system.
1677
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 nobats [PPC] Do not use BATs for mapping kernel lowmem
1679 on "Classic" PPC cores.
1680
1681 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001682
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001683 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1684
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001685 nodelayacct [KNL] Disable per-task delay accounting
1686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1688
Paul Mundt6902aa82008-09-21 17:14:42 +09001689 nodsp [SH] Disable hardware DSP at boot time.
1690
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301691 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 noexec [IA-64]
1694
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301695 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001696 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001698 noexec=off: disable non-executable mappings
1699
1700 noexec32 [X86-64]
1701 This affects only 32-bit executables.
1702 noexec32=on: enable non-executable mappings (default)
1703 read doesn't imply executable mappings
1704 noexec32=off: disable non-executable mappings
1705 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706
Paul Mundt6902aa82008-09-21 17:14:42 +09001707 nofpu [SH] Disable hardware FPU at boot time.
1708
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001709 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001710 register save and restore. The kernel will only save
1711 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
Suresh Siddha0c752a92009-05-22 12:17:45 -07001713 noxsave [BUGS=X86] Disables x86 extended register state save
1714 and restore using xsave. The kernel will fallback to
1715 enabling legacy floating-point and sse state.
1716
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001717 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1718 wfi(ARM) instruction doesn't work correctly and not to
1719 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001720
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001721 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 instruction doesn't work correctly and not to
1723 use it.
1724
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001725 no_file_caps Tells the kernel not to honor file capabilities. The
1726 only way then for a file to be executed with privilege
1727 is to be setuid root or executed by root.
1728
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 nohalt [IA-64] Tells the kernel not to use the power saving
1730 function PAL_HALT_LIGHT when idle. This increases
1731 power-consumption. On the positive side, it reduces
1732 interrupt wake-up latency, which may improve performance
1733 in certain environments such as networked servers or
1734 real-time systems.
1735
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001736 nohz= [KNL] Boottime enable/disable dynamic ticks
1737 Valid arguments: on, off
1738 Default: on
1739
Paul Mundteeee7852009-04-02 12:31:16 +09001740 noiotrap [SH] Disables trapped I/O port accesses.
1741
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001742 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 disable unhandled interrupt sources.
1744
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301745 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001746 broken timer IRQ sources.
1747
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 noisapnp [ISAPNP] Disables ISA PnP code.
1749
1750 noinitrd [RAM] Tells the kernel not to load any configured
1751 initial RAM disk.
1752
Weidong Han03ea8152009-04-17 16:42:15 +08001753 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1754 remapping.
1755
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756 nointroute [IA-64]
1757
Tony Luck0aa366f2007-07-20 11:22:30 -07001758 nojitter [IA64] Disables jitter checking for ITC timers.
1759
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001760 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001762 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001763
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 noltlbs [PPC] Do not use large page/tlb entries for kernel
1765 lowmem mapping on PPC40x.
1766
Horms312f1f02006-02-22 09:57:55 +09001767 nomca [IA-64] Disable machine check abort handling
1768
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001769 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001770
Andres Salomon83d73842007-10-12 23:04:06 +02001771 nomfgpt [X86-32] Disable Multi-Function General Purpose
1772 Timer usage (for AMD Geode machines).
1773
Jiri Kosina016ddd92010-01-18 17:05:40 +01001774 nopat [X86] Disable PAT (page attribute table extension of
1775 pagetables) support.
1776
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001777 norandmaps Don't use address space randomization. Equivalent to
1778 echo 0 > /proc/sys/kernel/randomize_va_space
1779
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001780 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001781
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001782 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001783 with UP alternatives
1784
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 noresidual [PPC] Don't use residual data on PReP machines.
1786
Randy Dunlapa9913042005-10-23 12:57:11 -07001787 noresume [SWSUSP] Disables resume and restores original swap
1788 space.
1789
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 no-scroll [VGA] Disables scrollback.
1791 This is required for the Braillex ib80-piezo Braille
1792 reader made by F.H. Papenmeier (Germany).
1793
1794 nosbagart [IA-64]
1795
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001796 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001797
Len Brown61ec7562007-08-16 03:34:22 -04001798 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1799 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800
Dave Jones97842212007-07-15 23:41:05 -07001801 nosoftlockup [KNL] Disable the soft-lockup detector.
1802
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001803 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001804 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001805
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 nosync [HW,M68K] Disables sync negotiation for all devices.
1807
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001808 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809
1810 nousb [USB] Disable the USB subsystem
1811
Don Zickus58687ac2010-05-07 17:11:44 -04001812 nowatchdog [KNL] Disable the lockup detector.
1813
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 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 Dunlap7c4be252009-01-06 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 oprofile.timer= [HW]
1852 Use timer interrupt instead of performance counters
1853
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001854 oprofile.cpu_type= Force an oprofile cpu type
1855 This might be useful if you have an older oprofile
1856 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001857 Format: { arch_perfmon }
1858 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001859 perfmon on Intel CPUs instead of the
1860 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001861
Randy Dunlapbcfde332010-06-07 17:10:38 -07001862 OSS [HW,OSS]
1863 See Documentation/sound/oss/oss-parameters.txt
1864
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
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 pas16= [HW,SCSI]
1902 See header of drivers/scsi/pas16.c.
1903
Andrew Mortondd287792006-03-23 03:00:57 -08001904 pause_on_oops=
1905 Halt all CPUs after the first oops has been printed for
1906 the specified number of seconds. This is to be used if
1907 your oopses keep scrolling off the screen.
1908
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 pcbit= [HW,ISDN]
1910
1911 pcd. [PARIDE]
1912 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001913 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914
Randy Dunlapa9913042005-10-23 12:57:11 -07001915 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001916 earlydump [X86] dump PCI config space before the kernel
1917 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001918 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001919 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001920 the hardware directly. Use this if your machine
1921 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001922 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001923 hardware access methods are allowed. Use this
1924 if you experience crashes upon bootup and you
1925 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001926 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001927 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001928 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001929 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001930 noaer [PCIE] If the PCIEAER kernel config parameter is
1931 enabled, this kernel boot option can be used to
1932 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001933 nodomains [PCI] Disable support for multiple PCI
1934 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301935 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001936 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001937 check_enable_amd_mmconf [X86] check for and enable
1938 properly configured MMIO access to PCI
1939 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001940 nomsi [MSI] If the PCI_MSI kernel config parameter is
1941 enabled, this kernel boot option can be used to
1942 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001943 noioapicquirk [APIC] Disable all boot interrupt quirks.
1944 Safety option to keep boot IRQs enabled. This
1945 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001946 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1947 primary IO-APIC for bridges that cannot disable
1948 boot IRQs. This fixes a source of spurious IRQs
1949 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001950 noioapicreroute [APIC] Disable workaround that uses the
1951 boot IRQ equivalent of an IRQ that connects to
1952 a chipset where boot IRQs cannot be disabled.
1953 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001954 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001955 routing table. These calls are known to be buggy
1956 on several machines and they hang the machine
1957 when used, but on other computers it's the only
1958 way to get the interrupt routing table. Try
1959 this option if the kernel is unable to allocate
1960 IRQs or discover secondary PCI buses on your
1961 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001962 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001963 Use with caution as certain devices share
1964 address decoders between ROMs and other
1965 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001966 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001967 expansion ROMs that do not already have
1968 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07001969 nobar [X86] Do not assign address space to the
1970 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001971 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001972 assigned automatically to PCI devices. You can
1973 make the kernel exclude IRQs of your ISA cards
1974 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001975 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001976 of the PIRQ table (normally generated
1977 by the BIOS) if it is outside the
1978 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001979 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001980 useful if the kernel is unable to find your
1981 secondary buses and you want to tell it
1982 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001983 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001984 numbers ourselves, overriding
1985 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001986 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001987 in the BIOS $PIR table. This is needed on
1988 some systems with broken BIOSes, notably
1989 some HP Pavilion N5400 and Omnibook XE3
1990 notebooks. This will have no effect if ACPI
1991 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001992 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001993 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001994 use_crs [X86] Use PCI host bridge window information
1995 from ACPI. On BIOSes from 2008 or later, this
1996 is enabled by default. If you need to use this,
1997 please report a bug.
1998 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1999 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002000 routeirq Do IRQ routing for all PCI devices.
2001 This is normally done in pci_enable_device(),
2002 so this option is a temporary workaround
2003 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002004 skip_isa_align [X86] do not align io start addr, so can
2005 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002006 firmware [ARM] Do not re-enumerate the bus but instead
2007 just use the configuration from the
2008 bootloader. This is currently used on
2009 IXP2000 systems where the bus has to be
2010 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002011 noearly [X86] Don't do any early type 1 scanning.
2012 This might help on some broken boards which
2013 machine check when some devices' config space
2014 is read. But various workarounds are disabled
2015 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002016 bfsort Sort PCI devices into breadth-first order.
2017 This sorting is done to get a device
2018 order compatible with older (<= 2.4) kernels.
2019 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002020 cbiosize=nn[KMG] The fixed amount of bus space which is
2021 reserved for the CardBus bridge's IO window.
2022 The default value is 256 bytes.
2023 cbmemsize=nn[KMG] The fixed amount of bus space which is
2024 reserved for the CardBus bridge's memory
2025 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002026 resource_alignment=
2027 Format:
2028 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2029 Specifies alignment and device to reassign
2030 aligned memory resources.
2031 If <order of align> is not specified,
2032 PAGE_SIZE is used as alignment.
2033 PCI-PCI bridge can be specified, if resource
2034 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002035 ecrc= Enable/disable PCIe ECRC (transaction layer
2036 end-to-end CRC checking).
2037 bios: Use BIOS/firmware settings. This is the
2038 the default.
2039 off: Turn ECRC off
2040 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002041
Chuck Ebberte5665a42008-09-24 20:40:34 -04002042 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2043 Management.
2044 off Disable ASPM.
2045 force Enable ASPM even on devices that claim not to support it.
2046 WARNING: Forcing ASPM on may cause system lockups.
2047
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002048 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockib27759f2010-06-18 17:04:22 +02002049 Format: {auto|force}[,nomsi]
2050 auto Use native PCIe PME signaling if the BIOS allows the
2051 kernel to control PCIe config registers of root ports.
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002052 force Use native PCIe PME signaling even if the BIOS refuses
2053 to allow the kernel to control the relevant PCIe config
2054 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002055 nomsi Do not use MSI for native PCIe PME signaling (this makes
2056 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002057
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 pcmv= [HW,PCMCIA] BadgePAD 4
2059
2060 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002061 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062
2063 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2064 boot time.
2065 Format: { 0 | 1 }
2066 See arch/parisc/kernel/pdc_chassis.c
2067
Tejun Heof58dc012009-08-14 15:00:50 +09002068 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002069 Currently supported values are "embed" and "page".
2070 Archs may support subset or none of the selections.
2071 See comments in mm/percpu.c for details on each
2072 allocator. This parameter is primarily for debugging
2073 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002074
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002076 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077
2078 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002079 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
2081 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002082 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
2084 plip= [PPT,NET] Parallel port network link
2085 Format: { parport<nr> | timid | 0 }
2086 See also Documentation/parport.txt.
2087
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002088 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2089 Override pmtimer IOPort with a hex value.
2090 e.g. pmtmr=0x508
2091
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002092 pnp.debug [PNP]
2093 Enable PNP debug messages. This depends on the
2094 CONFIG_PNP_DEBUG_MESSAGES option.
2095
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096 pnpacpi= [ACPI]
2097 { off }
2098
2099 pnpbios= [ISAPNP]
2100 { on | off | curr | res | no-curr | no-res }
2101
2102 pnp_reserve_irq=
2103 [ISAPNP] Exclude IRQs for the autoconfiguration
2104
2105 pnp_reserve_dma=
2106 [ISAPNP] Exclude DMAs for the autoconfiguration
2107
2108 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002109 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110
2111 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002112 [ISAPNP] Exclude memory regions for the
2113 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114 Ranges are in pairs (memory base and size).
2115
Randy Dunlap4af94f32009-04-17 18:30:28 -07002116 ports= [IP_VS_FTP] IPVS ftp helper module
2117 Default is 21.
2118 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2119 may be specified.
2120 Format: <port>,<port>....
2121
Ingo Molnar45807a12007-07-15 23:40:10 -07002122 print-fatal-signals=
2123 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002124
2125 If enabled, warn about various signal handling
2126 related application anomalies: too many signals,
2127 too many POSIX.1 timers, fatal signals causing a
2128 coredump - etc.
2129
2130 If you hit the warning due to signal overflow,
2131 you might want to try "ulimit -i unlimited".
2132
Ingo Molnar45807a12007-07-15 23:40:10 -07002133 default: off.
2134
Randy Dunlape84845c2007-07-15 23:40:25 -07002135 printk.time= Show timing data prefixed to each printk message line
2136 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2137
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002138 processor.max_cstate= [HW,ACPI]
2139 Limit processor to maximum C-state
2140 max_cstate=9 overrides any DMI blacklist limit.
2141
2142 processor.nocst [HW,ACPI]
2143 Ignore the _CST method to determine C-states,
2144 instead using the legacy FADT method
2145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002147 Format: [schedule,]<number>
2148 Param: "schedule" - profile schedule points.
2149 Param: <number> - step/bucket size as a power of 2 for
2150 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002151 Param: "sleep" - profile D-state sleeping (millisecs).
2152 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002153 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2156 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002157 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158
Randy Dunlapa9913042005-10-23 12:57:11 -07002159 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2160 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2162 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002163 psmouse.resetafter= [HW,MOUSE]
2164 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 (0 = never).
2166 psmouse.resolution=
2167 [HW,MOUSE] Set desired mouse resolution, in dpi.
2168 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002169 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 0 = disabled, 1 = enabled (default).
2171
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002173 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
Kay Sieversdc8c8582007-08-15 12:25:38 +02002175 pty.legacy_count=
2176 [KNL] Number of legacy pty's. Overwrites compiled-in
2177 default number.
2178
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002179 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002180
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 r128= [HW,DRM]
2182
2183 raid= [HW,RAID]
2184 See Documentation/md.txt.
2185
Randy Dunlapa9913042005-10-23 12:57:11 -07002186 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002187 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002188
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002190 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002192 rcupdate.blimit= [KNL,BOOT]
2193 Set maximum number of finished RCU callbacks to process
2194 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002195
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002196 rcupdate.qhimark= [KNL,BOOT]
2197 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002198 RCU callbacks over which batch limiting is disabled.
2199
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002200 rcupdate.qlowmark= [KNL,BOOT]
2201 Set threshold of queued RCU callbacks below which
2202 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002203
Olof Johanssonffdfc402005-09-06 15:17:19 -07002204 rdinit= [KNL]
2205 Format: <full_path>
2206 Run specified binary instead of /init from the ramdisk,
2207 used for early userspace startup. See initrd.
2208
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002209 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002211 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212
Paul Jackson46b6d942008-07-04 10:00:09 -07002213 relax_domain_level=
2214 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002215 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002216
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2218
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002219 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002220 Format: nn[KMG]
2221 Reserves a hole at the top of the kernel virtual
2222 address space.
2223
Vivek Goyal7e962872006-09-27 01:50:44 -07002224 reset_devices [KNL] Force drivers to reset the underlying device
2225 during initialization.
2226
Randy Dunlapa9913042005-10-23 12:57:11 -07002227 resume= [SWSUSP]
2228 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002230 resume_offset= [SWSUSP]
2231 Specify the offset from the beginning of the partition
2232 given by "resume=" at which the swap header is located,
2233 in <PAGE_SIZE> units (needed only for swap files).
2234 See Documentation/power/swsusp-and-swap-files.txt
2235
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002236 retain_initrd [RAM] Keep initrd memory after extraction
2237
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 rhash_entries= [KNL,NET]
2239 Set number of hash buckets for route cache
2240
2241 riscom8= [HW,SERIAL]
2242 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2243
2244 ro [KNL] Mount root device read-only on boot
2245
2246 root= [KNL] Root filesystem
2247
2248 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2249 mount the root filesystem
2250
2251 rootflags= [KNL] Set root filesystem mount option string
2252
2253 rootfstype= [KNL] Set root filesystem type
2254
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002255 rootwait [KNL] Wait (indefinitely) for root device to show up.
2256 Useful for devices that are detected asynchronously
2257 (e.g. USB and MMC devices).
2258
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259 rw [KNL] Mount root device read-write on boot
2260
2261 S [KNL] Run init in single mode
2262
2263 sa1100ir [NET]
2264 See drivers/net/irda/sa1100_ir.c.
2265
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002267
Mike Travisf6630112009-11-17 18:22:15 -06002268 sched_debug [KNL] Enables verbose scheduler debug messages.
2269
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 scsi_debug_*= [SCSI]
2271 See drivers/scsi/scsi_debug.c.
2272
2273 scsi_default_dev_flags=
2274 [SCSI] SCSI default device flags
2275 Format: <integer>
2276
2277 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2278 Format: <vendor>:<model>:<flags>
2279 (flags are integer value)
2280
Randy Dunlap6af66322007-11-14 16:52:25 -08002281 scsi_logging_level= [SCSI] a bit mask of logging levels
2282 See drivers/scsi/scsi_logging.h for bits. Also
2283 settable via sysctl at dev.scsi.logging_level
2284 (/proc/sys/dev/scsi/logging_level).
2285 There is also a nice 'scsi_logging_level' script in the
2286 S390-tools package, available for download at
2287 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002289 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2290 discovered. async scans them in kernel threads,
2291 allowing boot to proceed. none ignores them, expecting
2292 user space to do the scan.
2293
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002294 security= [SECURITY] Choose a security module to enable at boot.
2295 If this boot parameter is not specified, only the first
2296 security module asking for security registration will be
2297 loaded. An invalid security module name will be treated
2298 as if no module has been chosen.
2299
2300 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 Format: { "0" | "1" }
2302 See security/selinux/Kconfig help text.
2303 0 -- disable.
2304 1 -- enable.
2305 Default value is set via kernel config option.
2306 If enabled at boot time, /selinux/disable can be used
2307 later to disable prior to initial policy load.
2308
John Johansenc1c124e2010-07-29 14:48:09 -07002309 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2310 Format: { "0" | "1" }
2311 See security/apparmor/Kconfig help text
2312 0 -- disable.
2313 1 -- enable.
2314 Default value is set via kernel config option.
2315
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002316 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002317
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 shapers= [NET]
2319 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002320
Yinghai Lub05f78f2008-08-22 01:32:50 -07002321 show_msr= [x86] show boot-time MSR settings
2322 Format: { <integer> }
2323 Show boot-time (BIOS-initialized) MSR settings.
2324 The parameter means the number of CPUs to show,
2325 for example 1 means boot CPU only.
2326
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 sim710= [SCSI,HW]
2328 See header of drivers/scsi/sim710.c.
2329
2330 simeth= [IA-64]
2331 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002332
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 slram= [HW,MTD]
2334
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002335 slub_debug[=options[,slabs]] [MM, SLUB]
2336 Enabling slub_debug allows one to determine the
2337 culprit if slab objects become corrupted. Enabling
2338 slub_debug can create guard zones around objects and
2339 may poison objects when not in use. Also tracks the
2340 last alloc / free. For more information see
2341 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002342
2343 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002344 Determines the maximum allowed order for slabs.
2345 A high setting may cause OOMs due to memory
2346 fragmentation. For more information see
2347 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002348
2349 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002350 The minimum number of objects per slab. SLUB will
2351 increase the slab order up to slub_max_order to
2352 generate a sufficiently large slab able to contain
2353 the number of objects indicated. The higher the number
2354 of objects the smaller the overhead of tracking slabs
2355 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002356 For more information see Documentation/vm/slub.txt.
2357
2358 slub_min_order= [MM, SLUB]
2359 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002360 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002361 For more information see Documentation/vm/slub.txt.
2362
2363 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002364 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002365 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002366 allocs to different slabs. Debug options disable
2367 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002368 For more information see Documentation/vm/slub.txt.
2369
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 smart2= [HW]
2371 Format: <io1>[,<io2>[,...,<io8>]]
2372
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002373 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002374 attempt to substitute SMP alternatives once at boot.
2375
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002376 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2377 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2378 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2379 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2380 smsc-ircc2.ircc_irq= [HW] IRQ line
2381 smsc-ircc2.ircc_dma= [HW] DMA channel
2382 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2383 0: Toshiba Satellite 1800 (GP data pin select)
2384 1: Fast pin select (default)
2385 2: ATC IRMode
2386
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002387 softlockup_panic=
2388 [KNL] Should the soft-lockup detector generate panics.
2389
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2391 See Documentation/sonypi.txt
2392
2393 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002394 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002395
2396 spia_io_base= [HW,MTD]
2397 spia_fio_base=
2398 spia_pedr=
2399 spia_peddr=
2400
Linus Torvalds1da177e2005-04-16 15:20:36 -07002401 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2402 See Documentation/scsi/st.txt.
2403
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002404 stacktrace [FTRACE]
2405 Enabled the stack tracer on boot up.
2406
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407 sti= [PARISC,HW]
2408 Format: <num>
2409 Set the STI (builtin display/keyboard on the HP-PARISC
2410 machines) console (graphic card) which should be used
2411 as the initial boot-console.
2412 See also comment in drivers/video/console/sticore.c.
2413
2414 sti_font= [HW]
2415 See comment in drivers/video/console/sticore.c.
2416
2417 stifb= [HW]
2418 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2419
Trond Myklebustcbf11072009-08-09 15:06:19 -04002420 sunrpc.min_resvport=
2421 sunrpc.max_resvport=
2422 [NFS,SUNRPC]
2423 SunRPC servers often require that client requests
2424 originate from a privileged port (i.e. a port in the
2425 range 0 < portnr < 1024).
2426 An administrator who wishes to reserve some of these
2427 ports for other uses may adjust the range that the
2428 kernel's sunrpc client considers to be privileged
2429 using these two parameters to set the minimum and
2430 maximum port values.
2431
Greg Banks42a7fc42007-03-06 01:42:23 -08002432 sunrpc.pool_mode=
2433 [NFS]
2434 Control how the NFS server code allocates CPUs to
2435 service thread pools. Depending on how many NICs
2436 you have and where their interrupts are bound, this
2437 option will affect which CPUs will do NFS serving.
2438 Note: this parameter cannot be changed while the
2439 NFS server is running.
2440
2441 auto the server chooses an appropriate mode
2442 automatically using heuristics
2443 global a single global pool contains all CPUs
2444 percpu one pool for each CPU
2445 pernode one pool for each NUMA node (equivalent
2446 to global on non-NUMA machines)
2447
Trond Myklebustcbf11072009-08-09 15:06:19 -04002448 sunrpc.tcp_slot_table_entries=
2449 sunrpc.udp_slot_table_entries=
2450 [NFS,SUNRPC]
2451 Sets the upper limit on the number of simultaneous
2452 RPC calls that can be sent from the client to a
2453 server. Increasing these values may allow you to
2454 improve throughput, but will also increase the
2455 amount of memory reserved for use by the client.
2456
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002458
Linus Torvalds1da177e2005-04-16 15:20:36 -07002459 switches= [HW,M68k]
2460
2461 sym53c416= [HW,SCSI]
2462 See header of drivers/scsi/sym53c416.c.
2463
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002464 sysrq_always_enabled
2465 [KNL]
2466 Ignore sysrq setting - this boot parameter will
2467 neutralize any effect of /proc/sys/kernel/sysrq.
2468 Useful for debugging.
2469
Linus Torvalds1da177e2005-04-16 15:20:36 -07002470 t128= [HW,SCSI]
2471 See header of drivers/scsi/t128.c.
2472
2473 tdfx= [HW,DRM]
2474
David Brownell77437fd2008-07-23 21:28:33 -07002475 test_suspend= [SUSPEND]
2476 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2477 standby suspend) as the system sleep state to briefly
2478 enter during system startup. The system is woken from
2479 this state using a wakeup-capable RTC alarm.
2480
Linus Torvalds1da177e2005-04-16 15:20:36 -07002481 thash_entries= [KNL,NET]
2482 Set number of hash buckets for TCP connection
2483
Len Brownf8707ec2007-08-12 00:12:54 -04002484 thermal.act= [HW,ACPI]
2485 -1: disable all active trip points in all thermal zones
2486 <degrees C>: override all lowest active trip points
2487
Len Brownc52a7412007-08-14 15:49:32 -04002488 thermal.crt= [HW,ACPI]
2489 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002490 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002491
Len Brownf5487142007-08-12 00:12:44 -04002492 thermal.nocrt= [HW,ACPI]
2493 Set to disable actions on ACPI thermal zone
2494 critical and hot trip points.
2495
Len Brown72b33ef2007-08-12 00:12:17 -04002496 thermal.off= [HW,ACPI]
2497 1: disable ACPI thermal control
2498
Len Browna70cdc52007-08-12 00:12:35 -04002499 thermal.psv= [HW,ACPI]
2500 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002501 <degrees C>: override all passive trip points to this
2502 value
Len Browna70cdc52007-08-12 00:12:35 -04002503
Len Brown730ff342007-08-12 00:12:26 -04002504 thermal.tzp= [HW,ACPI]
2505 Specify global default ACPI thermal zone polling rate
2506 <deci-seconds>: poll all this frequency
2507 0: no polling (default)
2508
Linus Torvalds1da177e2005-04-16 15:20:36 -07002509 tmscsim= [HW,SCSI]
2510 See comment before function dc390_setup() in
2511 drivers/scsi/tmscsim.c.
2512
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002513 topology= [S390]
2514 Format: {off | on}
2515 Specify if the kernel should make use of the cpu
2516 topology informations if the hardware supports these.
2517 The scheduler will make use of these informations and
2518 e.g. base its process migration decisions on it.
2519 Default is off.
2520
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521 tp720= [HW,PS2]
2522
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002523 tpm_suspend_pcr=[HW,TPM]
2524 Format: integer pcr id
2525 Specify that at suspend time, the tpm driver
2526 should extend the specified pcr with zeros,
2527 as a workaround for some chips which fail to
2528 flush the last written pcr on TPM_SaveState.
2529 This will guarantee that all the other pcrs
2530 are saved.
2531
Li Zefan9d612be2009-06-24 17:33:15 +08002532 trace_buf_size=nn[KMG]
2533 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002534
Li Zefan020e5f82009-07-01 10:47:05 +08002535 trace_event=[event-list]
2536 [FTRACE] Set and start specified trace events in order
2537 to facilitate early boot debugging.
2538 See also Documentation/trace/events.txt
2539
Alok Kataria395628e2008-10-24 17:22:01 -07002540 tsc= Disable clocksource-must-verify flag for TSC.
2541 Format: <string>
2542 [x86] reliable: mark tsc clocksource as reliable, this
2543 disables clocksource verification at runtime.
2544 Used to enable high-resolution timer mode on older
2545 hardware, and in virtualized environment.
2546
Randy Dunlapa9913042005-10-23 12:57:11 -07002547 turbografx.map[2|3]= [HW,JOY]
2548 TurboGraFX parallel port interface
2549 Format:
2550 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002551 See also Documentation/input/joystick-parport.txt
2552
2553 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2554 See header of drivers/scsi/u14-34f.c.
2555
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002556 uhash_entries= [KNL,NET]
2557 Set number of hash buckets for UDP/UDP-Lite connections
2558
Alan Stern5f8364b2006-12-05 16:29:55 -05002559 uhci-hcd.ignore_oc=
2560 [USB] Ignore overcurrent events (default N).
2561 Some badly-designed motherboards generate lots of
2562 bogus events, for ports that aren't wired to
2563 anything. Set this parameter to avoid log spamming.
2564 Note that genuine overcurrent events won't be
2565 reported either.
2566
Simon Arlotte3a61b02008-07-19 23:32:54 +01002567 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302568 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002569 Set unknown_nmi_panic=1 early on boot.
2570
Alan Sternb5e795f2007-02-20 15:00:53 -05002571 usbcore.autosuspend=
2572 [USB] The autosuspend time delay (in seconds) used
2573 for newly-detected USB devices (default 2). This
2574 is the time required before an idle device will be
2575 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002576 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002577
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002578 usbcore.usbfs_snoop=
2579 [USB] Set to log all usbfs traffic (default 0 = off).
2580
2581 usbcore.blinkenlights=
2582 [USB] Set to cycle leds on hubs (default 0 = off).
2583
2584 usbcore.old_scheme_first=
2585 [USB] Start with the old device initialization
2586 scheme (default 0 = off).
2587
2588 usbcore.use_both_schemes=
2589 [USB] Try the other device initialization scheme
2590 if the first one fails (default 1 = enabled).
2591
2592 usbcore.initial_descriptor_timeout=
2593 [USB] Specifies timeout for the initial 64-byte
2594 USB_REQ_GET_DESCRIPTOR request in milliseconds
2595 (default 5000 = 5.0 seconds).
2596
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597 usbhid.mousepoll=
2598 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002599
Alan Sternd4f373e2008-11-10 14:07:45 -05002600 usb-storage.delay_use=
2601 [UMS] The delay in seconds before a new device is
2602 scanned for Logical Units (default 5).
2603
2604 usb-storage.quirks=
2605 [UMS] A list of quirks entries to supplement or
2606 override the built-in unusual_devs list. List
2607 entries are separated by commas. Each entry has
2608 the form VID:PID:Flags where VID and PID are Vendor
2609 and Product ID values (4-digit hex numbers) and
2610 Flags is a set of characters, each corresponding
2611 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002612 a = SANE_SENSE (collect more than 18 bytes
2613 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002614 b = BAD_SENSE (don't collect more than 18
2615 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002616 c = FIX_CAPACITY (decrease the reported
2617 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002618 h = CAPACITY_HEURISTICS (decrease the
2619 reported device capacity by one
2620 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002621 i = IGNORE_DEVICE (don't bind to this
2622 device);
2623 l = NOT_LOCKABLE (don't try to lock and
2624 unlock ejectable media);
2625 m = MAX_SECTORS_64 (don't transfer more
2626 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002627 o = CAPACITY_OK (accept the capacity
2628 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002629 r = IGNORE_RESIDUE (the device reports
2630 bogus residue values);
2631 s = SINGLE_LUN (the device has only one
2632 Logical Unit);
2633 w = NO_WP_DETECT (don't test whether the
2634 medium is write-protected).
2635 Example: quirks=0419:aaf5:rl,0421:0433:rc
2636
Ian Campbell14315592010-02-17 10:38:10 +00002637 userpte=
2638 [X86] Flags controlling user PTE allocations.
2639
2640 nohigh = do not allocate PTE pages in
2641 HIGHMEM regardless of setting
2642 of CONFIG_HIGHPTE.
2643
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302644 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002645 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002646 vdso=1: enable VDSO (default)
2647 vdso=0: disable VDSO mapping
2648
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302649 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002650 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2651 vdso32=1: enable 32-bit VDSO (default)
2652 vdso32=0: disable 32-bit VDSO mapping
2653
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002654 vector= [IA-64,SMP]
2655 vector=percpu: enable percpu vector domain
2656
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 video= [FB] Frame buffer configuration
2658 See Documentation/fb/modedb.txt.
2659
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002660 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002661 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002662 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663 Use vga=ask for menu.
2664 This is actually a boot loader parameter; the value is
2665 passed to the kernel using a special protocol.
2666
Randy Dunlapa9913042005-10-23 12:57:11 -07002667 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668 size of <nn>. This can be used to increase the
2669 minimum size (128MB on x86). It can also be used to
2670 decrease the size and leave more room for directly
2671 mapped kernel RAM.
2672
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002673 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2674 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002675
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002676 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2677 Format: <command>
2678
2679 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2680 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002681
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002682 vt.cur_default= [VT] Default cursor shape.
2683 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2684 the parameters of the <Esc>[?A;B;Cc escape sequence;
2685 see VGA-softcursor.txt. Default: 2 = underline.
2686
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002687 vt.default_blu= [VT]
2688 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2689 Change the default blue palette of the console.
2690 This is a 16-member array composed of values
2691 ranging from 0-255.
2692
2693 vt.default_grn= [VT]
2694 Format: <green0>,<green1>,<green2>,...,<green15>
2695 Change the default green palette of the console.
2696 This is a 16-member array composed of values
2697 ranging from 0-255.
2698
2699 vt.default_red= [VT]
2700 Format: <red0>,<red1>,<red2>,...,<red15>
2701 Change the default red palette of the console.
2702 This is a 16-member array composed of values
2703 ranging from 0-255.
2704
2705 vt.default_utf8=
2706 [VT]
2707 Format=<0|1>
2708 Set system-wide default UTF-8 mode for all tty's.
2709 Default is 1, i.e. UTF-8 mode is enabled for all
2710 newly opened terminals.
2711
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002712 vt.global_cursor_default=
2713 [VT]
2714 Format=<-1|0|1>
2715 Set system-wide default for whether a cursor
2716 is shown on new VTs. Default is -1,
2717 i.e. cursors will be created by default unless
2718 overridden by individual drivers. 0 will hide
2719 cursors, 1 will display them.
2720
Linus Torvalds1da177e2005-04-16 15:20:36 -07002721 wd33c93= [HW,SCSI]
2722 See header of drivers/scsi/wd33c93.c.
2723
2724 wd7000= [HW,SCSI]
2725 See header of drivers/scsi/wd7000.c.
2726
Randy Dunlap4724ba52010-05-03 11:42:52 -07002727 watchdog timers [HW,WDT] For information on watchdog timers,
2728 see Documentation/watchdog/watchdog-parameters.txt
2729 or other driver-specific files in the
2730 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002732 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2733 default x2apic cluster mode on platforms
2734 supporting x2apic.
2735
Jacob Panbb24c472009-09-02 07:37:17 -07002736 x86_mrst_timer= [X86-32,APBT]
2737 Choose timer option for x86 Moorestown MID platform.
2738 Two valid options are apbt timer only and lapic timer
2739 plus one apbt timer for broadcast timer.
2740 x86_mrst_timer=apbt_only | lapic_and_apbt
2741
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2743 xd_geo= See header of drivers/block/xd.c.
2744
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002745 xen_emul_unplug= [HW,X86,XEN]
2746 Unplug Xen emulated devices
2747 Format: [unplug0,][unplug1]
2748 ide-disks -- unplug primary master IDE devices
2749 aux-ide-disks -- unplug non-primary-master IDE devices
2750 nics -- unplug network devices
2751 all -- unplug all emulated devices (NICs and IDE disks)
2752 ignore -- continue loading the Xen platform PCI driver even
2753 if the version check failed
2754
Linus Torvalds1da177e2005-04-16 15:20:36 -07002755 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002756 Format:
2757 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002758
Randy Dunlapa9913042005-10-23 12:57:11 -07002759______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760
2761TODO:
2762
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763 Add more DRM drivers.