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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.
51 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050053 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070055 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 ISAPNP ISA PnP code is enabled.
57 ISDN Appropriate ISDN support is enabled.
58 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070059 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 LP Printer support is enabled.
61 LOOP Loopback device support is enabled.
62 M68k M68k architecture is enabled.
63 These options have more detailed description inside of
64 Documentation/m68k/kernel-options.txt.
65 MCA MCA bus support is enabled.
66 MDA MDA console support is enabled.
67 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070068 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070069 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 NET Appropriate network support is enabled.
71 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070072 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 NFS Appropriate NFS support is enabled.
74 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070075 PV_OPS A paravirtualized kernel is enabled.
76 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 PARISC The PA-RISC architecture is enabled.
78 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070079 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 PCMCIA The PCMCIA subsystem is enabled.
81 PNP Plug & Play support is enabled.
82 PPC PowerPC architecture is enabled.
83 PPT Parallel port support is enabled.
84 PS2 Appropriate PS/2 support is enabled.
85 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070086 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 S390 S390 architecture is enabled.
88 SCSI Appropriate SCSI support is enabled.
89 A lot of drivers has their options described inside of
90 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070091 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 SELINUX SELinux support is enabled.
93 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090094 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 SMP The kernel is an SMP kernel.
96 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070097 SWSUSP Software suspend (hibernation) is enabled.
98 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -050099 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500101 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 USB USB support is enabled.
103 USBHID USB Human Interface Device support is enabled.
104 V4L Video For Linux support is enabled.
105 VGA The VGA console has been enabled.
106 VT Virtual terminal support is enabled.
107 WDT Watchdog support is enabled.
108 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700109 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 X86-64 X86-64 architecture is enabled.
111 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700112 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200113 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115In addition, the following text indicates that the option:
116
117 BUGS= Relates to possible processor bugs on the said processor.
118 KNL Is a kernel start-up parameter.
119 BOOT Is a boot loader parameter.
120
121Parameters denoted with BOOT are actually interpreted by the boot
122loader, and have no meaning to the kernel directly.
123Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500124need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125
Karsten Weiss55588702007-02-13 13:26:21 +0100126There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700127See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
130a trailing = on the name of any parameter states that that parameter will
131be entered as an environment variable, whereas its absence indicates that
132it will appear as a kernel argument readable via /proc/cmdline by programs
133running once the system is up.
134
jens m. noedler9c4751f2006-09-29 02:00:27 -0700135The number of kernel parameters is not limited, but the length of the
136complete command line (parameters including spaces etc.) is limited to
137a fixed number of characters. This limit depends on the architecture
138and is between 256 and 4096 characters. It is defined in the file
139./include/asm/setup.h as COMMAND_LINE_SIZE.
140
141
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530142 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800143 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800144 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 force -- enable ACPI if default was off
146 off -- disable ACPI if default was on
147 noirq -- do not use ACPI for IRQ routing
148 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700149 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800151 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
Randy Dunlap53471122008-03-12 18:10:51 -0400153 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Len Browna1fdcc02007-03-11 03:26:14 -0400155 acpi_apic_instance= [ACPI, IOAPIC]
156 Format: <int>
157 2: use 2nd APIC table, if available
158 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400159 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400160
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200161 acpi_backlight= [HW,ACPI]
162 acpi_backlight=vendor
163 acpi_backlight=video
164 If set to vendor, prefer vendor specific driver
165 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
166 of the ACPI video.ko driver.
167
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700168 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
169 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700171 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
172 debug output. Bits in debug_layer correspond to a
173 _COMPONENT in an ACPI source file, e.g.,
174 #define _COMPONENT ACPI_PCI_COMPONENT
175 Bits in debug_level correspond to a level in
176 ACPI_DEBUG_PRINT statements, e.g.,
177 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600178 The debug_level mask defaults to "info". See
179 Documentation/acpi/debug.txt for more information about
180 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600182 Enable processor driver info messages:
183 acpi.debug_layer=0x20000000
184 Enable PCI/PCI interrupt routing info messages:
185 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700186 Enable AML "Debug" output, i.e., stores to the Debug
187 object while interpreting AML:
188 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700189 Enable all messages related to ACPI hardware:
190 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200191
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700192 Some values produce so much output that the system is
193 unusable. The "log_buf_len" parameter may be useful
194 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800195
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700196 acpi_display_output= [HW,ACPI]
197 acpi_display_output=vendor
198 acpi_display_output=video
199 See above.
200
201 acpi_irq_balance [HW,ACPI]
202 ACPI will balance active IRQs
203 default in APIC mode
204
205 acpi_irq_nobalance [HW,ACPI]
206 ACPI will not move active IRQs (default)
207 default in PIC mode
208
209 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
210 Format: <irq>,<irq>...
211
212 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
213 use by PCI
214 Format: <irq>,<irq>...
215
216 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
217
218 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
219 Format: To spoof as Windows 98: ="Microsoft Windows"
220
221 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
222 acpi_osi="string1" # add string1 -- only one string
223 acpi_osi="!string2" # remove built-in string2
224 acpi_osi= # disable all strings
225
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530226 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
230
Zhao Yakuif5adfaa2008-08-11 14:57:50 +0800231 acpi.power_nocheck= [HW,ACPI]
232 Format: 1/0 enable/disable the check of power state.
233 On some bogus BIOS the _PSC object/_STA object of
234 power resource can't return the correct device power
235 state. In such case it is unneccessary to check its
236 power state again in power transition.
237 1 : disable the power state check
238
Randy Dunlap4af94f32009-04-17 18:30:28 -0700239 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
240 Format: { level | edge | high | low }
241
242 acpi_serialize [HW,ACPI] force serialization of AML methods
243
244 acpi_skip_timer_override [HW,ACPI]
245 Recognize and ignore IRQ0/pin2 Interrupt Override.
246 For broken nForce2 BIOS resulting in XT-PIC timer.
247
248 acpi_sleep= [HW,ACPI] Sleep options
249 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
250 old_ordering, s4_nonvs }
251 See Documentation/power/video.txt for information on
252 s3_bios and s3_mode.
253 s3_beep is for debugging; it makes the PC's speaker beep
254 as soon as the kernel's real-mode entry point is called.
255 s4_nohwsig prevents ACPI hardware signature from being
256 used during resume from hibernation.
257 old_ordering causes the ACPI 1.0 ordering of the _PTS
258 control method, with respect to putting devices into
259 low power states, to be enforced (the ACPI 2.0 ordering
260 of _PTS is used by default).
261 s4_nonvs prevents the kernel from saving/restoring the
262 ACPI NVS memory during hibernation.
263
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
286
Randy Dunlap4af94f32009-04-17 18:30:28 -0700287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 advansys= [HW,SCSI]
291 See header of drivers/scsi/advansys.c.
292
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
295
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700299
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700300 agp= [AGP]
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 aha152x= [HW,SCSI]
307 See Documentation/scsi/aha152x.txt.
308
309 aha1542= [HW,SCSI]
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
311
312 aic7xxx= [HW,SCSI]
313 See Documentation/scsi/aic7xxx.txt.
314
315 aic79xx= [HW,SCSI]
316 See Documentation/scsi/aic79xx.txt.
317
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
320 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100323 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100324 share - put every device behind one IOMMU into the
325 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
329 is a lot of faster
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
333 Format: <a>,<b>
334 See also Documentation/kernel/input/joystick.txt
335
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
340
Randy Dunlapa9913042005-10-23 12:57:11 -0700341 apc= [HW,SPARC]
342 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 Format: noidle
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
347
Randy Dunlapca1eda22009-05-06 16:02:58 -0700348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700349 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700353
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700355 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
358 Format: <io>,<irq>,<nodeID>
359
360 ataflop= [HW,M68k]
361
362 atarimouse= [HW,MOUSE] Atari Mouse
363
364 atascsi= [HW,SCSI] Atari SCSI
365
366 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
367 EzKey and similar keyboards
368
369 atkbd.reset= [HW] Reset keyboard during initialization
370
Randy Dunlapa9913042005-10-23 12:57:11 -0700371 atkbd.set= [HW] Select keyboard code set
372 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373
374 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
375 keyboards
376
377 atkbd.softraw= [HW] Choose between synthetic and real raw mode
378 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700379
380 atkbd.softrepeat= [HW]
381 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 autotest [IA64]
384
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 baycom_epp= [HW,AX25]
386 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700387
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
389 Format: <io>,<mode>
390 See header of drivers/net/hamradio/baycom_par.c.
391
Randy Dunlapa9913042005-10-23 12:57:11 -0700392 baycom_ser_fdx= [HW,AX25]
393 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 Format: <io>,<irq>,<mode>[,<baud>]
395 See header of drivers/net/hamradio/baycom_ser_fdx.c.
396
Randy Dunlapa9913042005-10-23 12:57:11 -0700397 baycom_ser_hdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 Format: <io>,<irq>,<mode>
400 See header of drivers/net/hamradio/baycom_ser_hdx.c.
401
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700402 boot_delay= Milliseconds to delay each printk during boot.
403 Values larger than 10 seconds (10000) are changed to
404 no delay (0).
405 Format: integer
406
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700407 bootmem_debug [KNL] Enable bootmem allocator debug messages.
408
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700410 bttv.radio= Most important insmod options are available as
411 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
413 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
414
415 BusLogic= [HW,SCSI]
416 See drivers/scsi/BusLogic.c, comment before function
417 BusLogic_ParseDriverOptions().
418
419 c101= [NET] Moxa C101 synchronous serial card
420
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700421 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 Sometimes CPU hardware bugs make them report the cache
423 size incorrectly. The kernel will attempt work arounds
424 to fix known problems, but for some CPUs it is not
425 possible to determine what the correct size should be.
426 This option provides an override for these situations.
427
James Morris20510f22007-10-16 23:31:32 -0700428 capability.disable=
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
433
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436
Paul Menage8bab8dd2008-04-04 14:29:57 -0700437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
440
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700448 Value can be changed at runtime via
449 /selinux/checkreqprot.
450
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100451 cio_ignore= [S390]
452 See Documentation/s390/CommonIO for details.
453
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700455 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200456 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700457 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200458 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 Format: { pit | tsc | cyclone | pmtmr }
460
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700461 clocksource= [GENERIC_TIME] Override the default clocksource
462 Format: <string>
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
466 the platform:
467 [all] jiffies (this is the base, fallback clocksource)
468 [ACPI] acpi_pm
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
471 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700472 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700473 scx200_hrt on Geode; cyclone on IBM x440
474 [MIPS] MIPS
475 [PARISC] cr16
476 [S390] tod
477 [SH] SuperH
478 [SPARC64] tick
479 [X86-64] hpet,tsc
480
Andi Kleenac72e782008-01-30 13:33:21 +0100481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800483 arch/x86/include/asm/cpufeature.h for the valid bit
484 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100485 stable over kernel options, but the vendor specific
486 ones should be.
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
492 some critical bits.
493
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530494 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100495 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100496 Range: 0 - 8192
497 Default: 64
498
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700500 Format:
501 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502
503 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
504 Format: <io>[,<irq>]
505
Randy Dunlapa9913042005-10-23 12:57:11 -0700506 com90xx= [HW,NET]
507 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 Format: <io>[,<irq>[,<memstart>]]
509
510 condev= [HW,S390] console device
511 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700512
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 console= [KNL] Output console device and options.
514
515 tty<n> Use the virtual console device <n>.
516
517 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800518 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800520 the form "bbbbpnf", where "bbbb" is the baud rate,
521 "p" is parity ("n", "o", or "e"), "n" is number of
522 bits, and "f" is flow control ("r" for RTS or
523 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800525 See Documentation/serial-console.txt for more
526 information. See
527 Documentation/networking/netconsole.txt for an
528 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700530 uart[8250],io,<addr>[,options]
531 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 Start an early, polled-mode console on the 8250/16550
533 UART at the specified I/O port or MMIO address,
534 switching to the matching ttyS device later. The
535 options are the same as for ttyS, above.
536
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700537 If the device connected to the port is not a TTY but a braille
538 device, prepend "brl," before the device type, for instance
539 console=brl,ttyS0
540 For now, only VisioBraille is supported.
541
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800542 coredump_filter=
543 [KNL] Change the default value for
544 /proc/<pid>/coredump_filter.
545 See also Documentation/filesystems/proc.txt.
546
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700548 Format:
549 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700551 crashkernel=nn[KMG]@ss[KMG]
552 [KNL] Reserve a chunk of physical memory to
553 hold a kernel to switch to with kexec on panic.
554
Bernhard Wallefb391592007-10-18 23:41:02 -0700555 crashkernel=range1:size1[,range2:size2,...][@offset]
556 [KNL] Same as above, but depends on the memory
557 in the running system. The syntax of range is
558 start-[end] where start and end are both
559 a memory unit (amount[KMG]). See also
560 Documentation/kdump/kdump.txt for a example.
561
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 cs89x0_dma= [HW,NET]
563 Format: <dma>
564
565 cs89x0_media= [HW,NET]
566 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700567
Randy Dunlapa9913042005-10-23 12:57:11 -0700568 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 See header of drivers/s390/block/dasd_devmap.c.
570
571 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
572 (one device per port)
573 Format: <port#>,<type>
574 See also Documentation/input/joystick-parport.txt
575
576 debug [KNL] Enable kernel debugging (events log level).
577
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700578 debug_locks_verbose=
579 [KNL] verbose self-tests
580 Format=<0|1>
581 Print debugging info while doing the locking API
582 self-tests.
583 We default to 0 (no extra messages), setting it to
584 1 will print _a lot_ more information - normally
585 only useful to kernel developers.
586
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700587 debug_objects [KNL] Enable object debugging
588
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500589 no_debug_objects
590 [KNL] Disable object debugging
591
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200592 debugpat [X86] Enable PAT debugging
593
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200594 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 Format: <area>[,<node>]
596 See also Documentation/networking/decnet.txt.
597
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700598 default_hugepagesz=
599 [same as hugepagesz=] The size of the default
600 HugeTLB page size. This is the size represented by
601 the legacy /proc/ hugepages APIs, used for SHM, and
602 default size when mounting hugetlbfs filesystems.
603 Defaults to the default architecture's huge page size
604 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 dhash_entries= [KNL]
607 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 digi= [HW,SERIAL]
610 IO parameters + enable/disable command.
611
612 digiepca= [HW,SERIAL]
613 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000614 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
Yinghai Lu95ffa242008-04-29 03:52:33 -0700616 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700617 The kernel tries to adjust MTRR layout from continuous
618 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700619 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700620
Yinghai Lu093af8d2008-01-30 13:33:32 +0100621 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100622 By default the kernel will trim any uncacheable
623 memory out of your available memory pool based on
624 MTRR settings. This parameter disables that behavior,
625 possibly causing your machine to run very slowly.
626
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530627 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700628 Disable PIN 1 of APIC timer
629 Can be useful to work around chipset bugs.
630
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 dmasound= [HW,OSS] Sound subsystem buffers
632
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700633 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
634 this option disables the debugging code at boot.
635
636 dma_debug_entries=<number>
637 This option allows to tune the number of preallocated
638 entries for DMA-API debugging code. One entry is
639 required per DMA-API allocation. Use this if the
640 DMA-API debugging code disables itself because the
641 architectural default is too low.
642
Joerg Roedel1745de52009-05-22 21:49:51 +0200643 dma_debug_driver=<driver_name>
644 With this option the DMA-API debugging driver
645 filter feature can be enabled at boot time. Just
646 pass the driver to filter for as the parameter.
647 The filter can be disabled or changed to another
648 driver later using sysfs.
649
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 dscc4.setup= [NET]
651
652 dtc3181e= [HW,SCSI]
653
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 dynamic_printk Enables pr_debug()/dev_dbg() calls if
655 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
656 These can also be switched on/off via
657 <debugfs>/dynamic_printk/modules
658
659 earlycon= [KNL] Output early console device and options.
660 uart[8250],io,<addr>[,options]
661 uart[8250],mmio,<addr>[,options]
662 Start an early, polled-mode console on the 8250/16550
663 UART at the specified I/O port or MMIO address.
664 The options are the same as for ttyS, above.
665
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530666 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 earlyprintk=vga
668 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700669 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670
Randy Dunlapa9913042005-10-23 12:57:11 -0700671 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 takes over.
673
Yinghai Lu5c059172008-07-24 17:29:40 -0700674 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
676 Currently only ttyS0 and ttyS1 are supported.
677
678 Interaction with the standard serial driver is not
679 very good.
680
681 The VGA output is eventually overwritten by the real
682 console.
683
684 eata= [HW,SCSI]
685
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700687 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 eisa_irq_edge= [PARISC,HW]
690 See header of drivers/parisc/eisa.c.
691
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700692 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700694 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695
696 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800697 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700698 See Documentation/block/as-iosched.txt and
699 Documentation/block/deadline-iosched.txt for details.
700
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530701 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700702 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800703 image elf header. Generally kexec loader will
704 pass this option to capture kernel.
705 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700707 enable_mtrr_cleanup [X86]
708 The kernel tries to adjust MTRR layout from continuous
709 to discrete, to make X server driver able to add WB
710 entry later. This parameter enables that.
711
Randy Dunlapca1eda22009-05-06 16:02:58 -0700712 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700713 Enable PIN 1 of APIC timer
714 Can be useful to work around chipset bugs
715 (in particular on some ATI chipsets).
716 The kernel tries to set a reasonable default.
717
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 enforcing [SELINUX] Set initial enforcing status.
719 Format: {"0" | "1"}
720 See security/selinux/Kconfig help text.
721 0 -- permissive (log only, no denials).
722 1 -- enforcing (deny and log).
723 Default value is 0.
724 Value can be changed at runtime via /selinux/enforce.
725
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 ether= [HW,NET] Ethernet cards parameters
727 This option is obsoleted by the "netdev=" option, which
728 has equivalent usage. See its documentation for details.
729
730 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
731 Format: <io>[,<irq>]
732
Akinobu Mitade1ba092006-12-08 02:39:42 -0800733 failslab=
734 fail_page_alloc=
735 fail_make_request=[KNL]
736 General fault injection mechanism.
737 Format: <interval>,<probability>,<space>,<times>
738 See also /Documentation/fault-injection/.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 fd_mcs= [HW,SCSI]
741 See header of drivers/scsi/fd_mcs.c.
742
743 fdomain= [HW,SCSI]
744 See header of drivers/scsi/fdomain.c.
745
746 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000747 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
Alex Chiangf13ae302008-05-08 14:03:23 -0600749 force_pal_cache_flush
750 [IA-64] Avoid check_sal_cache_flush which may hang on
751 buggy SAL_CACHE_FLUSH implementations. Using this
752 parameter will force ia64_sal_cache_flush to call
753 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
754
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100755 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400756 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100757 as early as possible in order to facilitate early
758 boot debugging.
759
760 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400761 [FTRACE] will dump the trace buffers on oops.
762
763 ftrace_filter=[function-list]
764 [FTRACE] Limit the functions traced by the function
765 tracer at boot up. function-list is a comma separated
766 list of functions. This list can be changed at run
767 time by the set_ftrace_filter file in the debugfs
768 tracing directory.
769
770 ftrace_notrace=[function-list]
771 [FTRACE] Do not trace the functions specified in
772 function-list. This list can be changed at run time
773 by the set_ftrace_notrace file in the debugfs
774 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100775
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 gamecon.map[2|3]=
777 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
778 support via parallel port (up to 5 devices per port)
779 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
780 See also Documentation/input/joystick-parport.txt
781
782 gamma= [HW,DRM]
783
Yinghai Luaaf23042008-01-30 13:33:09 +0100784 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
785 Format: off | on
786 default: on
787
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 gdth= [HW,SCSI]
789 See header of drivers/scsi/gdth.c.
790
791 gpt [EFI] Forces disk with valid GPT signature but
792 invalid Protective MBR to be treated as GPT.
793
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 gvp11= [HW,SCSI]
795
796 hashdist= [KNL,NUMA] Large hashes allocated during boot
797 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700798 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700799 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801 hcl= [IA-64] SGI's Hardware Graph compatibility layer
802
803 hd= [EIDE] (E)IDE hard drive subsystem geometry
804 Format: <cyl>,<head>,<sect>
805
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
807 size of <nn>. This works even on boxes that have no
808 highmem otherwise. This also works to reduce highmem
809 size on bigger boxes.
810
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800811 highres= [KNL] Enable/disable high resolution timer mode.
812 Valid parameters: "on", "off"
813 Default: "on"
814
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 hisax= [HW,ISDN]
816 See Documentation/isdn/README.HiSax.
817
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700818 hlt [BUGS=ARM,SH]
819
820 hpet= [X86-32,HPET] option to control HPET usage
821 Format: { enable (default) | disable | force |
822 verbose }
823 disable: disable HPET and use PIT instead
824 force: allow force enabled of undocumented chips (ICH4,
825 VIA, nVidia)
826 verbose: show contents of HPET registers during setup
827
Andi Kleenb4718e62008-07-23 21:27:51 -0700828 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
829 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700830 On x86-64 and powerpc, this option can be specified
831 multiple times interleaved with hugepages= to reserve
832 huge pages of different sizes. Valid pages sizes on
833 x86-64 are 2M (when the CPU supports "pse") and 1G
834 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700835 Note that 1GB pages can only be allocated at boot time
836 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900837
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100838 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
839 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100840 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
841 If specified, z/VM IUCV HVC accepts connections
842 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100843
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700844 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700845 or register an additional I2C bus that is not
846 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700847 Format:
848 <bus_id>,<clkrate>
849
Jiri Kosina36d95732008-10-06 02:51:09 -0400850 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200852 i8042.dumbkbd [HW] Pretend that controller can only read data from
853 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 (Don't attempt to blink the leds)
855 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500856 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400857 i8042.noloop [HW] Disable the AUX Loopback command while probing
858 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 i8042.nomux [HW] Don't check presence of an active multiplexing
860 controller
861 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
862 controllers
863 i8042.panicblink=
864 [HW] Frequency with which keyboard LEDs should blink
865 when kernel panics (default is 0.5 sec)
866 i8042.reset [HW] Reset the controller during init and cleanup
867 i8042.unlock [HW] Unlock (ignore) the keylock
868
869 i810= [HW,DRM]
870
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700871 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
872 indicates that the driver is running on unsupported
873 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
875 does not match list of supported models.
876 i8k.power_status
877 [HW] Report power status in /proc/i8k
878 (disabled by default)
879 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
880 capability is set.
881
882 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
883 See Documentation/mca.txt.
884
885 icn= [HW,ISDN]
886 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
887
David Fries0af80c02009-02-25 20:28:21 +0100888 ide-core.nodma= [HW] (E)IDE subsystem
889 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200890 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
891 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100892 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700894 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
895 Claim all unknown PCI IDE storage controllers.
896
Andi Kleenf039b752007-05-02 19:27:12 +0200897 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800898 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
899 Poll forces a polling idle loop that can slightly
900 improve the performance of waking up a idle CPU, but
901 will use a lot of power and make the system run hot.
902 Not recommended.
903 idle=mwait: On systems which support MONITOR/MWAIT but
904 the kernel chose to not use it because it doesn't save
905 as much power as a normal idle loop, use the
906 MONITOR/MWAIT idle loop anyways. Performance should be
907 the same as idle=poll.
908 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800909 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800910 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700911
Ingo Molnar792908222006-12-06 20:40:51 -0800912 ignore_loglevel [KNL]
913 Ignore loglevel setting - this will print /all/
914 kernel messages to the console. Useful for debugging.
915
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 ihash_entries= [KNL]
917 Set number of hash buckets for inode cache.
918
Mimi Zohar3323eec92009-02-04 09:06:58 -0500919 ima_audit= [IMA]
920 Format: { "0" | "1" }
921 0 -- integrity auditing messages. (Default)
922 1 -- enable informational integrity auditing messages.
923
924 ima_hash= [IMA]
925 Formt: { "sha1" | "md5" }
926 default: "sha1"
927
Eric Paris5789ba32009-05-21 15:47:06 -0400928 ima_tcb [IMA]
929 Load a policy which meets the needs of the Trusted
930 Computing Base. This means IMA will measure all
931 programs exec'd, files mmap'd for exec, and all files
932 opened for read by uid=0.
933
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 in2000= [HW,SCSI]
935 See header of drivers/scsi/in2000.c.
936
937 init= [KNL]
938 Format: <full_path>
939 Run specified binary instead of /sbin/init as init
940 process.
941
942 initcall_debug [KNL] Trace initcalls as they are executed. Useful
943 for working out where the kernel is dying during
944 startup.
945
946 initrd= [BOOT] Specify the location of the initial ramdisk
947
948 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
949 Format: <irq>
950
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700951 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800952 on
953 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700954 off
955 Disable intel iommu driver.
956 igfx_off [Default Off]
957 By default, gfx is mapped as normal device. If a gfx
958 device has a dedicated DMAR unit, the DMAR unit is
959 bypassed by not enabling DMAR with this option. In
960 this case, gfx device will use physical address for
961 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700962 forcedac [x86_64]
963 With this option iommu will not optimize to look
964 for io virtual address below 32 bit forcing dual
965 address cycle on pci bus for cards supporting greater
966 than 32 bit addressing. The default is to look
967 for translation below 32 bit and if not available
968 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800969 strict [Default Off]
970 With this option on every unmap_single operation will
971 result in a hardware IOTLB flush operation as opposed
972 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700973
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700974 inttest= [IA64]
975
976 iomem= Disable strict checking of access to MMIO memory
977 strict regions from userspace.
978 relaxed
979
980 iommu= [x86]
981 off
982 force
983 noforce
984 biomerge
985 panic
986 nopanic
987 merge
988 nomerge
989 forcesac
990 soft
991
992 io7= [HW] IO7 for Marvel based alpha systems
993 See comment before marvel_specify_io7 in
994 arch/alpha/kernel/core_marvel.c.
995
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530996 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100997 0x80
998 Standard port 0x80 based delay
999 0xed
1000 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001001 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001002 Simple two microseconds delay
1003 none
1004 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001005
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001007 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008
1009 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001010 See comment before ip2_setup() in
1011 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012
1013 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1014 See header of drivers/scsi/ips.c.
1015
Alan Cox200803d2005-06-28 20:45:18 -07001016 irqfixup [HW]
1017 When an interrupt is not handled search all handlers
1018 for it. Intended to get systems with badly broken
1019 firmware running.
1020
1021 irqpoll [HW]
1022 When an interrupt is not handled search all handlers
1023 for it. Also check all handlers each timer
1024 interrupt. Intended to get systems with badly broken
1025 firmware running.
1026
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001028 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029
1030 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001031 Format:
1032 <cpu number>,...,<cpu number>
1033 or
Li Zefanb225d442008-11-06 12:53:39 -08001034 <cpu number>-<cpu number>
1035 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001036 or a mixture
1037 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001038
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 This option can be used to specify one or more CPUs
1040 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001041 algorithms. You can move a process onto or off an
1042 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 <cpu number> begins at 0 and the maximum value is
1044 "number of CPUs in system - 1".
1045
1046 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001047 alternative -- manually setting the CPU mask of all
1048 tasks in the system -- can cause problems and
1049 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
Randy Dunlapa9913042005-10-23 12:57:11 -07001051 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052
1053 js= [HW,JOY] Analog joystick
1054 See Documentation/input/joystick.txt.
1055
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001056 keepinitrd [HW,ARM]
1057
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301058 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001059 specifies the amount of memory usable by the kernel
1060 for non-movable allocations. The requested amount is
1061 spread evenly throughout all nodes in the system. The
1062 remaining memory in each node is used for Movable
1063 pages. In the event, a node is too small to have both
1064 kernelcore and Movable pages, kernelcore pages will
1065 take priority and other nodes will have a larger number
1066 of kernelcore pages. The Movable zone is used for the
1067 allocation of pages that may be reclaimed or moved
1068 by the page migration subsystem. This means that
1069 HugeTLB pages may not be allocated from this zone.
1070 Note that allocations like PTEs-from-HighMem still
1071 use the HighMem zone if it exists, and the Normal
1072 zone if it does not.
1073
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001074 kgdboc= [HW] kgdb over consoles.
1075 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001076 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001077 Format: <serial_device>[,baud]
1078
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001079 kmac= [MIPS] korina ethernet MAC address.
1080 Configure the RouterBoard 532 series on-chip
1081 Ethernet adapter MAC address.
1082
Catalin Marinas04f70332009-06-11 13:22:39 +01001083 kmemleak= [KNL] Boot-time kmemleak enable/disable
1084 Valid arguments: on, off
1085 Default: on
1086
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301087 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001088 in oops dumps.
1089
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090 l2cr= [PPC]
1091
Robert Brosea78bfbf2008-03-29 07:20:23 +11001092 l3cr= [PPC]
1093
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001094 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001095 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301097 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001098 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001099
FD Camifcb71f62008-01-06 19:08:56 +01001100 libata.dma= [LIBATA] DMA control
1101 libata.dma=0 Disable all PATA and SATA DMA
1102 libata.dma=1 PATA and SATA Disk DMA only
1103 libata.dma=2 ATAPI (CDROM) DMA only
1104 libata.dma=4 Compact Flash DMA only
1105 Combinations also work, so libata.dma=3 enables DMA
1106 for disks and CDROMs, but not CFs.
1107
Dave Jones78e70c22007-09-27 11:50:13 -04001108 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1109 when set.
1110 Format: <int>
1111
Tejun Heo33267322008-02-13 09:15:09 +09001112 libata.force= [LIBATA] Force configurations. The format is comma
1113 separated list of "[ID:]VAL" where ID is
1114 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1115 matching port, link or device. Basically, it matches
1116 the ATA ID string printed on console by libata. If
1117 the whole ID part is omitted, the last PORT and DEVICE
1118 values are used. If ID hasn't been specified yet, the
1119 configuration applies to all ports, links and devices.
1120
1121 If only DEVICE is omitted, the parameter applies to
1122 the port and all links and devices behind it. DEVICE
1123 number of 0 either selects the first device or the
1124 first fan-out link behind PMP device. It does not
1125 select the host link. DEVICE number of 15 selects the
1126 host link and device attached to it.
1127
1128 The VAL specifies the configuration to force. As long
1129 as there's no ambiguity shortcut notation is allowed.
1130 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1131 The following configurations can be forced.
1132
1133 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1134 Any ID with matching PORT is used.
1135
1136 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1137
1138 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1139 udma[/][16,25,33,44,66,100,133] notation is also
1140 allowed.
1141
1142 * [no]ncq: Turn on or off NCQ.
1143
Tejun Heo05944bd2008-08-13 20:19:09 +09001144 * nohrst, nosrst, norst: suppress hard, soft
1145 and both resets.
1146
Tejun Heo33267322008-02-13 09:15:09 +09001147 If there are multiple matching configurations changing
1148 the same attribute, the last one is used.
1149
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001150 lmb=debug [KNL] Enable lmb debug messages.
1151
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001153 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001155 lockd.nlm_grace_period=P [NFS] Assign grace period.
1156 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001158 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1159 Format: <integer>
1160
1161 lockd.nlm_timeout=T [NFS] Assign timeout value.
1162 Format: <integer>
1163
1164 lockd.nlm_udpport=M [NFS] Assign UDP port.
1165 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166
1167 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1168 Format: <irq>
1169
1170 loglevel= All Kernel Messages with a loglevel smaller than the
1171 console loglevel will be printed to the console. It can
1172 also be changed with klogd or other programs. The
1173 loglevels are defined as follows:
1174
1175 0 (KERN_EMERG) system is unusable
1176 1 (KERN_ALERT) action must be taken immediately
1177 2 (KERN_CRIT) critical conditions
1178 3 (KERN_ERR) error conditions
1179 4 (KERN_WARNING) warning conditions
1180 5 (KERN_NOTICE) normal but significant condition
1181 6 (KERN_INFO) informational
1182 7 (KERN_DEBUG) debug-level messages
1183
1184 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001185 Format: { n | nk | nM }
1186 n must be a power of two. The default size
1187 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188
Randy Dunlapaccaa242007-10-16 01:29:37 -07001189 logo.nologo [FB] Disables display of the built-in Linux logo.
1190 This may be used to provide more screen space for
1191 kernel log messages and is useful when debugging
1192 kernel boot problems.
1193
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 lp=0 [LP] Specify parallel ports to use, e.g,
1195 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1196 lp=reset first parallel port). 'lp=0' disables the
1197 lp=auto printer driver. 'lp=reset' (which can be
1198 specified in addition to the ports) causes
1199 attached printers to be reset. Using
1200 lp=port1,port2,... specifies the parallel ports
1201 to associate lp devices with, starting with
1202 lp0. A port specification may be 'none' to skip
1203 that lp device, or a parport name such as
1204 'parport0'. Specifying 'lp=auto' instead of a
1205 port specification list means that device IDs
1206 from each port should be examined, to see if
1207 an IEEE 1284-compliant printer is attached; if
1208 so, the driver will manage that printer.
1209 See also header of drivers/char/lp.c.
1210
1211 lpj=n [KNL]
1212 Sets loops_per_jiffy to given constant, thus avoiding
1213 time-consuming boot-time autodetection (up to 250 ms per
1214 CPU). 0 enables autodetection (default). To determine
1215 the correct value for your kernel, boot with normal
1216 autodetection and see what value is printed. Note that
1217 on SMP systems the preset will be applied to all CPUs,
1218 which is likely to cause problems if your CPUs need
1219 significantly divergent settings. An incorrect value
1220 will cause delays in the kernel to be wrong, leading to
1221 unpredictable I/O errors and other breakage. Although
1222 unlikely, in the extreme case this might damage your
1223 hardware.
1224
1225 ltpc= [NET]
1226 Format: <io>,<irq>,<dma>
1227
Randy Dunlapa9913042005-10-23 12:57:11 -07001228 mac5380= [HW,SCSI] Format:
1229 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
Randy Dunlapa9913042005-10-23 12:57:11 -07001231 machvec= [IA64] Force the use of a particular machine-vector
1232 (machvec) in a generic kernel.
1233 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001235 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1236 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
1238 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001239 should make use of. maxcpus=n : n >= 0 limits the
1240 kernel to using 'n' processors. n=0 is a special case,
1241 it is equivalent to "nosmp", which also disables
1242 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001244 max_loop= [LOOP] Maximum number of loopback devices that can
1245 be mounted
1246 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001247
Randy Dunlapa9913042005-10-23 12:57:11 -07001248 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249 Should be between 1 and 2^32-1.
1250
1251 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001252 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 Should be between 1 and 16384.
1254
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 mcatest= [IA-64]
1256
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001257 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258
Uwe Hermann71cced62008-10-20 09:32:21 -07001259 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001260
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 md= [HW] RAID subsystems devices and level
1262 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 mdacon= [MDA]
1265 Format: <first>,<last>
1266 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001267
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1269 Amount of memory to be used when the kernel is not able
1270 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001271 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 address space collisions. Without memmap= PCI devices
1273 could be placed at addresses belonging to unused RAM.
1274
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001275 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 memory.
1277
Paul Mundt6902aa82008-09-21 17:14:42 +09001278 memchunk=nn[KMG]
1279 [KNL,SH] Allow user to override the default size for
1280 per-device physically contiguous DMA buffers.
1281
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301282 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 E820 memory map, as specified by the user.
1284 Such memmap=exactmap lines can be constructed based on
1285 BIOS output or other requirements. See the memmap=nn@ss
1286 option description.
1287
1288 memmap=nn[KMG]@ss[KMG]
1289 [KNL] Force usage of a specific region of memory
1290 Region of memory to be used, from ss to ss+nn.
1291
1292 memmap=nn[KMG]#ss[KMG]
1293 [KNL,ACPI] Mark specific memory as ACPI data.
1294 Region of memory to be used, from ss to ss+nn.
1295
1296 memmap=nn[KMG]$ss[KMG]
1297 [KNL,ACPI] Mark specific memory as reserved.
1298 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001299 Example: Exclude memory from 0x18690000-0x1869ffff
1300 memmap=64K$0x18690000
1301 or
1302 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001304 memory_corruption_check=0/1 [X86]
1305 Some BIOSes seem to corrupt the first 64k of
1306 memory when doing things like suspend/resume.
1307 Setting this option will scan the memory
1308 looking for corruption. Enabling this will
1309 both detect corruption and prevent the kernel
1310 from using the memory being corrupted.
1311 However, its intended as a diagnostic tool; if
1312 repeatable BIOS-originated corruption always
1313 affects the same memory, you can use memmap=
1314 to prevent the kernel from using that memory.
1315
1316 memory_corruption_check_size=size [X86]
1317 By default it checks for corruption in the low
1318 64k, making this memory unavailable for normal
1319 use. Use this parameter to scan for
1320 corruption in more or less memory.
1321
1322 memory_corruption_check_period=seconds [X86]
1323 By default it checks for corruption every 60
1324 seconds. Use this parameter to check at some
1325 other rate. 0 disables periodic checking.
1326
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001327 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001328 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001329 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001330 Specifies the number of memtest passes to be
1331 performed. Each pass selects another test
1332 pattern from a given set of patterns. Memtest
1333 fills the memory with this pattern, validates
1334 memory contents and reserves bad memory
1335 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001336
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337 meye.*= [HW] Set MotionEye Camera parameters
1338 See Documentation/video4linux/meye.txt.
1339
Andres Salomon8f368812007-10-12 23:04:06 +02001340 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1341 Multi-Function General Purpose Timers on AMD Geode
1342 platforms.
1343
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001344 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1345 the BIOS has incorrectly applied a workaround. TinyBIOS
1346 version 0.98 is known to be affected, 0.99 fixes the
1347 problem by letting the user disable the workaround.
1348
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 mga= [HW,DRM]
1350
Randy Dunlap1c207f92008-11-19 15:36:16 -08001351 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1352 physical address is ignored.
1353
Michel Pollet39f45d72009-05-20 11:10:31 +01001354 mini2440= [ARM,HW,KNL]
1355 Format:[0..2][b][c][t]
1356 Default: "0tb"
1357 MINI2440 configuration specification:
1358 0 - The attached screen is the 3.5" TFT
1359 1 - The attached screen is the 7" TFT
1360 2 - The VGA Shield is attached (1024x768)
1361 Leaving out the screen size parameter will not load
1362 the TFT driver, and the framebuffer will be left
1363 unconfigured.
1364 b - Enable backlight. The TFT backlight pin will be
1365 linked to the kernel VESA blanking code and a GPIO
1366 LED. This parameter is not necessary when using the
1367 VGA shield.
1368 c - Enable the s3c camera interface.
1369 t - Reserved for enabling touchscreen support. The
1370 touchscreen support is not enabled in the mainstream
1371 kernel as of 2.6.30, a preliminary port can be found
1372 in the "bleeding edge" mini2440 support kernel at
1373 http://repo.or.cz/w/linux-2.6/mini2440.git
1374
Mel Gorman6b74ab92008-07-23 21:26:49 -07001375 mminit_loglevel=
1376 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1377 parameter allows control of the logging verbosity for
1378 the additional memory initialisation checks. A value
1379 of 0 disables mminit logging and a level of 4 will
1380 log everything. Information is printed at KERN_DEBUG
1381 so loglevel=8 may also need to be specified.
1382
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 mousedev.tap_time=
1384 [MOUSE] Maximum time between finger touching and
1385 leaving touchpad surface for touch to be considered
1386 a tap and be reported as a left button click (for
1387 touchpads working in absolute mode only).
1388 Format: <msecs>
1389 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1390 reporting absolute coordinates, such as tablets
1391 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1392 reporting absolute coordinates, such as tablets
1393
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301394 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001395 is similar to kernelcore except it specifies the
1396 amount of memory used for migratable allocations.
1397 If both kernelcore and movablecore is specified,
1398 then kernelcore will be at *least* the specified
1399 value but may be more. If movablecore on its own
1400 is specified, the administrator must be careful
1401 that the amount of memory usable for all allocations
1402 is not too small.
1403
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 mpu401= [HW,OSS]
1405 Format: <io>,<irq>
1406
1407 MTD_Partition= [MTD]
1408 Format: <name>,<region-number>,<size>,<offset>
1409
Randy Dunlapa9913042005-10-23 12:57:11 -07001410 MTD_Region= [MTD] Format:
1411 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412
1413 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001414 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415
Ben Dooks9db829f2008-07-03 11:24:29 +01001416 mtdset= [ARM]
1417 ARM/S3C2412 JIVE boot control
1418
1419 See arch/arm/mach-s3c2412/mach-jive.c
1420
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001422 [HW] Make the MicroTouch USB driver use raw coordinates
1423 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001425 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001426 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001427 that could hold holes aka. UC entries.
1428
1429 mtrr_gran_size=nn[KMG] [X86]
1430 Used for mtrr cleanup. It is granularity of mtrr block.
1431 Default is 1.
1432 Large value could prevent small alignment from
1433 using up MTRRs.
1434
1435 mtrr_spare_reg_nr=n [X86]
1436 Format: <integer>
1437 Range: 0,7 : spare reg number
1438 Default : 1
1439 Used for mtrr cleanup. It is spare mtrr entries number.
1440 Set to 2 or more if your graphical card needs more.
1441
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1443
1444 NCR_D700= [HW,SCSI]
1445 See header of drivers/scsi/NCR_D700.c.
1446
1447 ncr5380= [HW,SCSI]
1448
1449 ncr53c400= [HW,SCSI]
1450
1451 ncr53c400a= [HW,SCSI]
1452
1453 ncr53c406a= [HW,SCSI]
1454
1455 ncr53c8xx= [HW,SCSI]
1456
1457 netdev= [NET] Network devices parameters
1458 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1459 Note that mem_start is often overloaded to mean
1460 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001461 This usage is only documented in each driver source
1462 file if at all.
1463
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001464 nf_conntrack.acct=
1465 [NETFILTER] Enable connection tracking flow accounting
1466 0 to disable accounting
1467 1 to enable accounting
1468 Default value depends on CONFIG_NF_CT_ACCT that is
1469 going to be removed in 2.6.29.
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001472 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473
1474 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001475 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476
Trond Myklebusta72b4422006-01-03 09:55:41 +01001477 nfs.callback_tcpport=
1478 [NFS] set the TCP port on which the NFSv4 callback
1479 channel should listen.
1480
Trond Myklebust58df0952006-01-03 09:55:57 +01001481 nfs.idmap_cache_timeout=
1482 [NFS] set the maximum lifetime for idmapper cache
1483 entries.
1484
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001485 nfs.enable_ino64=
1486 [NFS] enable 64-bit inode numbers.
1487 If zero, the NFS client will fake up a 32-bit inode
1488 number for the readdir() and stat() syscalls instead
1489 of returning the full 64-bit number.
1490 The default is to return 64-bit inode numbers.
1491
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001492 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1493 when a NMI is triggered.
1494 Format: [state][,regs][,debounce][,die]
1495
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301496 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001497 Format: [panic,][num]
1498 Valid num: 0,1,2
1499 0 - turn nmi_watchdog off
1500 1 - use the IO-APIC timer for the NMI watchdog
1501 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001502 a performance counter. Note: This will use one
1503 performance counter and the local APIC's performance
1504 vector.
1505 When panic is specified, panic when an NMI watchdog
1506 timeout occurs.
1507 This is useful when you use a panic=... timeout and
1508 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001509 Instead of 1 and 2 it is possible to use the following
1510 symbolic names: lapic and ioapic
1511 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001513 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 emulation library even if a 387 maths coprocessor
1515 is present.
1516
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001517 no_console_suspend
1518 [HW] Never suspend the console
1519 Disable suspending of consoles during suspend and
1520 hibernate operations. Once disabled, debugging
1521 messages can reach various consoles while the rest
1522 of the system is being put to sleep (ie, while
1523 debugging driver suspend/resume hooks). This may
1524 not work reliably with all consoles, but is known
1525 to work with serial and VGA consoles.
1526
Christoph Lameterc1aee212007-05-31 00:40:47 -07001527 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1528 caches in the slab allocator. Saves per-node memory,
1529 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001530
Randy Dunlapa9913042005-10-23 12:57:11 -07001531 noalign [KNL,ARM]
1532
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 noapic [SMP,APIC] Tells the kernel to not make use of any
1534 IOAPICs that may be present in the system.
1535
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 nobats [PPC] Do not use BATs for mapping kernel lowmem
1537 on "Classic" PPC cores.
1538
1539 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001540
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001541 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1542
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001543 nodelayacct [KNL] Disable per-task delay accounting
1544
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1546
Paul Mundt6902aa82008-09-21 17:14:42 +09001547 nodsp [SH] Disable hardware DSP at boot time.
1548
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301549 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 noexec [IA-64]
1552
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301553 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001554 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001556 noexec=off: disable non-executable mappings
1557
1558 noexec32 [X86-64]
1559 This affects only 32-bit executables.
1560 noexec32=on: enable non-executable mappings (default)
1561 read doesn't imply executable mappings
1562 noexec32=off: disable non-executable mappings
1563 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564
Paul Mundt6902aa82008-09-21 17:14:42 +09001565 nofpu [SH] Disable hardware FPU at boot time.
1566
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001567 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001568 register save and restore. The kernel will only save
1569 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
Suresh Siddha0c752a92009-05-22 12:17:45 -07001571 noxsave [BUGS=X86] Disables x86 extended register state save
1572 and restore using xsave. The kernel will fallback to
1573 enabling legacy floating-point and sse state.
1574
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001575 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1576 wfi(ARM) instruction doesn't work correctly and not to
1577 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001578
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001579 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 instruction doesn't work correctly and not to
1581 use it.
1582
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001583 no_file_caps Tells the kernel not to honor file capabilities. The
1584 only way then for a file to be executed with privilege
1585 is to be setuid root or executed by root.
1586
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 nohalt [IA-64] Tells the kernel not to use the power saving
1588 function PAL_HALT_LIGHT when idle. This increases
1589 power-consumption. On the positive side, it reduces
1590 interrupt wake-up latency, which may improve performance
1591 in certain environments such as networked servers or
1592 real-time systems.
1593
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001594 nohz= [KNL] Boottime enable/disable dynamic ticks
1595 Valid arguments: on, off
1596 Default: on
1597
Paul Mundteeee7852009-04-02 12:31:16 +09001598 noiotrap [SH] Disables trapped I/O port accesses.
1599
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001600 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601 disable unhandled interrupt sources.
1602
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301603 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001604 broken timer IRQ sources.
1605
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606 noisapnp [ISAPNP] Disables ISA PnP code.
1607
1608 noinitrd [RAM] Tells the kernel not to load any configured
1609 initial RAM disk.
1610
Weidong Han03ea8152009-04-17 16:42:15 +08001611 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1612 remapping.
1613
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 nointroute [IA-64]
1615
Tony Luck0aa366f2007-07-20 11:22:30 -07001616 nojitter [IA64] Disables jitter checking for ITC timers.
1617
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001618 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001619
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001620 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001621
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622 noltlbs [PPC] Do not use large page/tlb entries for kernel
1623 lowmem mapping on PPC40x.
1624
Horms312f1f02006-02-22 09:57:55 +09001625 nomca [IA-64] Disable machine check abort handling
1626
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001627 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001628
Andres Salomon83d73842007-10-12 23:04:06 +02001629 nomfgpt [X86-32] Disable Multi-Function General Purpose
1630 Timer usage (for AMD Geode machines).
1631
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001632 norandmaps Don't use address space randomization. Equivalent to
1633 echo 0 > /proc/sys/kernel/randomize_va_space
1634
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001635 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001636
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001637 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001638 with UP alternatives
1639
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 noresidual [PPC] Don't use residual data on PReP machines.
1641
Randy Dunlapa9913042005-10-23 12:57:11 -07001642 noresume [SWSUSP] Disables resume and restores original swap
1643 space.
1644
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 no-scroll [VGA] Disables scrollback.
1646 This is required for the Braillex ib80-piezo Braille
1647 reader made by F.H. Papenmeier (Germany).
1648
1649 nosbagart [IA-64]
1650
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001651 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001652
Len Brown61ec7562007-08-16 03:34:22 -04001653 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1654 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655
Dave Jones97842212007-07-15 23:41:05 -07001656 nosoftlockup [KNL] Disable the soft-lockup detector.
1657
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001658 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001659 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001660
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 nosync [HW,M68K] Disables sync negotiation for all devices.
1662
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001663 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664
1665 nousb [USB] Disable the USB subsystem
1666
1667 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001668
Weidong Han2b2fd872009-04-17 16:42:12 +08001669 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1670
Fenghua Yua6c75b862008-03-14 13:57:08 -07001671 nptcg= [IA64] Override max number of concurrent global TLB
1672 purges which is reported from either PAL_VM_SUMMARY or
1673 SAL PALO.
1674
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001675 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1676
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001677 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1678 one of ['zone', 'node', 'default'] can be specified
1679 This can be set from sysctl after boot.
1680 See Documentation/sysctl/vm.txt for details.
1681
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001682 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1683 See Documentation/debugging-via-ohci1394.txt for more
1684 info.
1685
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001686 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1687 Rather than timing out after 20 ms if an EC
1688 command is not properly ACKed, override the length
1689 of the timeout. We have interrupts disabled while
1690 waiting for the ACK, so if this is set too high
1691 interrupts *may* be lost!
1692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 opl3= [HW,OSS]
1694 Format: <io>
1695
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 oprofile.timer= [HW]
1697 Use timer interrupt instead of performance counters
1698
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001699 oprofile.cpu_type= Force an oprofile cpu type
1700 This might be useful if you have an older oprofile
1701 userland or if you want common events.
1702 Format: { archperfmon }
1703 archperfmon: [X86] Force use of architectural
1704 perfmon on Intel CPUs instead of the
1705 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001706
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 osst= [HW,SCSI] SCSI Tape Driver
1708 Format: <buffer_size>,<write_threshold>
1709 See also Documentation/scsi/st.txt.
1710
1711 panic= [KNL] Kernel behaviour on panic
1712 Format: <timeout>
1713
1714 parkbd.port= [HW] Parallel port number the keyboard adapter is
1715 connected to, default is 0.
1716 Format: <parport#>
1717 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1718 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001719 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720
Randy Dunlapa9913042005-10-23 12:57:11 -07001721 parport= [HW,PPT] Specify parallel ports. 0 disables.
1722 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1723 Use 'auto' to force the driver to use any
1724 IRQ/DMA settings detected (the default is to
1725 ignore detected IRQ/DMA settings because of
1726 possible conflicts). You can specify the base
1727 address, IRQ, and DMA settings; IRQ and DMA
1728 should be numbers, or 'auto' (for using detected
1729 settings on that particular port), or 'nofifo'
1730 (to avoid using a FIFO even if it is detected).
1731 Parallel ports are assigned in the order they
1732 are specified on the command line, starting
1733 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734
Randy Dunlapa9913042005-10-23 12:57:11 -07001735 parport_init_mode= [HW,PPT]
1736 Configure VIA parallel port to operate in
1737 a specific mode. This is necessary on Pegasos
1738 computer where firmware has no options for setting
1739 up parallel port mode and sets it to spp.
1740 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 Format: [spp|ps2|epp|ecp|ecpepp]
1742
Randy Dunlapa9913042005-10-23 12:57:11 -07001743 pas2= [HW,OSS] Format:
1744 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1745
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 pas16= [HW,SCSI]
1747 See header of drivers/scsi/pas16.c.
1748
Andrew Mortondd287792006-03-23 03:00:57 -08001749 pause_on_oops=
1750 Halt all CPUs after the first oops has been printed for
1751 the specified number of seconds. This is to be used if
1752 your oopses keep scrolling off the screen.
1753
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754 pcbit= [HW,ISDN]
1755
1756 pcd. [PARIDE]
1757 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001758 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759
Randy Dunlapa9913042005-10-23 12:57:11 -07001760 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001761 earlydump [X86] dump PCI config space before the kernel
1762 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001763 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001765 the hardware directly. Use this if your machine
1766 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001767 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001768 hardware access methods are allowed. Use this
1769 if you experience crashes upon bootup and you
1770 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001771 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001772 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001773 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001774 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001775 noaer [PCIE] If the PCIEAER kernel config parameter is
1776 enabled, this kernel boot option can be used to
1777 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001778 nodomains [PCI] Disable support for multiple PCI
1779 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301780 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001781 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001782 nomsi [MSI] If the PCI_MSI kernel config parameter is
1783 enabled, this kernel boot option can be used to
1784 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001785 noioapicquirk [APIC] Disable all boot interrupt quirks.
1786 Safety option to keep boot IRQs enabled. This
1787 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001788 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1789 primary IO-APIC for bridges that cannot disable
1790 boot IRQs. This fixes a source of spurious IRQs
1791 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001792 noioapicreroute [APIC] Disable workaround that uses the
1793 boot IRQ equivalent of an IRQ that connects to
1794 a chipset where boot IRQs cannot be disabled.
1795 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001796 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001797 routing table. These calls are known to be buggy
1798 on several machines and they hang the machine
1799 when used, but on other computers it's the only
1800 way to get the interrupt routing table. Try
1801 this option if the kernel is unable to allocate
1802 IRQs or discover secondary PCI buses on your
1803 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001804 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001805 Use with caution as certain devices share
1806 address decoders between ROMs and other
1807 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001808 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001809 expansion ROMs that do not already have
1810 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001811 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001812 assigned automatically to PCI devices. You can
1813 make the kernel exclude IRQs of your ISA cards
1814 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001815 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001816 of the PIRQ table (normally generated
1817 by the BIOS) if it is outside the
1818 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001819 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001820 useful if the kernel is unable to find your
1821 secondary buses and you want to tell it
1822 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001823 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001824 numbers ourselves, overriding
1825 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001826 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001827 in the BIOS $PIR table. This is needed on
1828 some systems with broken BIOSes, notably
1829 some HP Pavilion N5400 and Omnibook XE3
1830 notebooks. This will have no effect if ACPI
1831 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001832 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001833 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001834 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001835 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001836 routeirq Do IRQ routing for all PCI devices.
1837 This is normally done in pci_enable_device(),
1838 so this option is a temporary workaround
1839 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001840 skip_isa_align [X86] do not align io start addr, so can
1841 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001842 firmware [ARM] Do not re-enumerate the bus but instead
1843 just use the configuration from the
1844 bootloader. This is currently used on
1845 IXP2000 systems where the bus has to be
1846 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001847 noearly [X86] Don't do any early type 1 scanning.
1848 This might help on some broken boards which
1849 machine check when some devices' config space
1850 is read. But various workarounds are disabled
1851 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001852 bfsort Sort PCI devices into breadth-first order.
1853 This sorting is done to get a device
1854 order compatible with older (<= 2.4) kernels.
1855 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001856 cbiosize=nn[KMG] The fixed amount of bus space which is
1857 reserved for the CardBus bridge's IO window.
1858 The default value is 256 bytes.
1859 cbmemsize=nn[KMG] The fixed amount of bus space which is
1860 reserved for the CardBus bridge's memory
1861 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09001862 resource_alignment=
1863 Format:
1864 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1865 Specifies alignment and device to reassign
1866 aligned memory resources.
1867 If <order of align> is not specified,
1868 PAGE_SIZE is used as alignment.
1869 PCI-PCI bridge can be specified, if resource
1870 windows need to be expanded.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001871
Chuck Ebberte5665a42008-09-24 20:40:34 -04001872 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1873 Management.
1874 off Disable ASPM.
1875 force Enable ASPM even on devices that claim not to support it.
1876 WARNING: Forcing ASPM on may cause system lockups.
1877
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 pcmv= [HW,PCMCIA] BadgePAD 4
1879
1880 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001881 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882
1883 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1884 boot time.
1885 Format: { 0 | 1 }
1886 See arch/parisc/kernel/pdc_chassis.c
1887
1888 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001889 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890
1891 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001892 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
1894 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001895 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
1897 plip= [PPT,NET] Parallel port network link
1898 Format: { parport<nr> | timid | 0 }
1899 See also Documentation/parport.txt.
1900
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001901 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1902 Override pmtimer IOPort with a hex value.
1903 e.g. pmtmr=0x508
1904
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001905 pnp.debug [PNP]
1906 Enable PNP debug messages. This depends on the
1907 CONFIG_PNP_DEBUG_MESSAGES option.
1908
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 pnpacpi= [ACPI]
1910 { off }
1911
1912 pnpbios= [ISAPNP]
1913 { on | off | curr | res | no-curr | no-res }
1914
1915 pnp_reserve_irq=
1916 [ISAPNP] Exclude IRQs for the autoconfiguration
1917
1918 pnp_reserve_dma=
1919 [ISAPNP] Exclude DMAs for the autoconfiguration
1920
1921 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001922 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923
1924 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001925 [ISAPNP] Exclude memory regions for the
1926 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001927 Ranges are in pairs (memory base and size).
1928
Randy Dunlap4af94f32009-04-17 18:30:28 -07001929 ports= [IP_VS_FTP] IPVS ftp helper module
1930 Default is 21.
1931 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1932 may be specified.
1933 Format: <port>,<port>....
1934
Ingo Molnar45807a12007-07-15 23:40:10 -07001935 print-fatal-signals=
1936 [KNL] debug: print fatal signals
1937 print-fatal-signals=1: print segfault info to
1938 the kernel console.
1939 default: off.
1940
Randy Dunlape84845c2007-07-15 23:40:25 -07001941 printk.time= Show timing data prefixed to each printk message line
1942 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1943
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001944 processor.max_cstate= [HW,ACPI]
1945 Limit processor to maximum C-state
1946 max_cstate=9 overrides any DMI blacklist limit.
1947
1948 processor.nocst [HW,ACPI]
1949 Ignore the _CST method to determine C-states,
1950 instead using the legacy FADT method
1951
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001953 Format: [schedule,]<number>
1954 Param: "schedule" - profile schedule points.
1955 Param: <number> - step/bucket size as a power of 2 for
1956 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001957 Param: "sleep" - profile D-state sleeping (millisecs).
1958 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001959 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1962 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001963 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964
Randy Dunlapa9913042005-10-23 12:57:11 -07001965 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1966 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1968 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001969 psmouse.resetafter= [HW,MOUSE]
1970 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 (0 = never).
1972 psmouse.resolution=
1973 [HW,MOUSE] Set desired mouse resolution, in dpi.
1974 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001975 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976 0 = disabled, 1 = enabled (default).
1977
1978 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001979 Format:
1980 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981
1982 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001983 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984
Kay Sieversdc8c8582007-08-15 12:25:38 +02001985 pty.legacy_count=
1986 [KNL] Number of legacy pty's. Overwrites compiled-in
1987 default number.
1988
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001989 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001990
Linus Torvalds1da177e2005-04-16 15:20:36 -07001991 r128= [HW,DRM]
1992
1993 raid= [HW,RAID]
1994 See Documentation/md.txt.
1995
Randy Dunlapa9913042005-10-23 12:57:11 -07001996 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001997 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001998
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002000 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002002 rcupdate.blimit= [KNL,BOOT]
2003 Set maximum number of finished RCU callbacks to process
2004 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002005
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002006 rcupdate.qhimark= [KNL,BOOT]
2007 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002008 RCU callbacks over which batch limiting is disabled.
2009
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002010 rcupdate.qlowmark= [KNL,BOOT]
2011 Set threshold of queued RCU callbacks below which
2012 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002013
Olof Johanssonffdfc402005-09-06 15:17:19 -07002014 rdinit= [KNL]
2015 Format: <full_path>
2016 Run specified binary instead of /init from the ramdisk,
2017 used for early userspace startup. See initrd.
2018
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002019 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002021 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022
Paul Jackson46b6d942008-07-04 10:00:09 -07002023 relax_domain_level=
2024 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002025 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002026
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2028
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002029 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002030 Format: nn[KMG]
2031 Reserves a hole at the top of the kernel virtual
2032 address space.
2033
Vivek Goyal7e962872006-09-27 01:50:44 -07002034 reset_devices [KNL] Force drivers to reset the underlying device
2035 during initialization.
2036
Randy Dunlapa9913042005-10-23 12:57:11 -07002037 resume= [SWSUSP]
2038 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002040 resume_offset= [SWSUSP]
2041 Specify the offset from the beginning of the partition
2042 given by "resume=" at which the swap header is located,
2043 in <PAGE_SIZE> units (needed only for swap files).
2044 See Documentation/power/swsusp-and-swap-files.txt
2045
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002046 retain_initrd [RAM] Keep initrd memory after extraction
2047
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 rhash_entries= [KNL,NET]
2049 Set number of hash buckets for route cache
2050
2051 riscom8= [HW,SERIAL]
2052 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2053
2054 ro [KNL] Mount root device read-only on boot
2055
2056 root= [KNL] Root filesystem
2057
2058 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2059 mount the root filesystem
2060
2061 rootflags= [KNL] Set root filesystem mount option string
2062
2063 rootfstype= [KNL] Set root filesystem type
2064
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002065 rootwait [KNL] Wait (indefinitely) for root device to show up.
2066 Useful for devices that are detected asynchronously
2067 (e.g. USB and MMC devices).
2068
James Morris20510f22007-10-16 23:31:32 -07002069 root_plug.vendor_id=
2070 [ROOTPLUG] Override the default vendor ID
2071
2072 root_plug.product_id=
2073 [ROOTPLUG] Override the default product ID
2074
2075 root_plug.debug=
2076 [ROOTPLUG] Enable debugging output
2077
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 rw [KNL] Mount root device read-write on boot
2079
2080 S [KNL] Run init in single mode
2081
2082 sa1100ir [NET]
2083 See drivers/net/irda/sa1100_ir.c.
2084
Linus Torvalds1da177e2005-04-16 15:20:36 -07002085 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002086
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2088 Format: <io>[,<timeout>[,<isapnp>]]
2089
2090 scsi_debug_*= [SCSI]
2091 See drivers/scsi/scsi_debug.c.
2092
2093 scsi_default_dev_flags=
2094 [SCSI] SCSI default device flags
2095 Format: <integer>
2096
2097 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2098 Format: <vendor>:<model>:<flags>
2099 (flags are integer value)
2100
Randy Dunlap6af66322007-11-14 16:52:25 -08002101 scsi_logging_level= [SCSI] a bit mask of logging levels
2102 See drivers/scsi/scsi_logging.h for bits. Also
2103 settable via sysctl at dev.scsi.logging_level
2104 (/proc/sys/dev/scsi/logging_level).
2105 There is also a nice 'scsi_logging_level' script in the
2106 S390-tools package, available for download at
2107 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002109 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2110 discovered. async scans them in kernel threads,
2111 allowing boot to proceed. none ignores them, expecting
2112 user space to do the scan.
2113
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002114 security= [SECURITY] Choose a security module to enable at boot.
2115 If this boot parameter is not specified, only the first
2116 security module asking for security registration will be
2117 loaded. An invalid security module name will be treated
2118 as if no module has been chosen.
2119
2120 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121 Format: { "0" | "1" }
2122 See security/selinux/Kconfig help text.
2123 0 -- disable.
2124 1 -- enable.
2125 Default value is set via kernel config option.
2126 If enabled at boot time, /selinux/disable can be used
2127 later to disable prior to initial policy load.
2128
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002129 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 shapers= [NET]
2132 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002133
Yinghai Lub05f78f2008-08-22 01:32:50 -07002134 show_msr= [x86] show boot-time MSR settings
2135 Format: { <integer> }
2136 Show boot-time (BIOS-initialized) MSR settings.
2137 The parameter means the number of CPUs to show,
2138 for example 1 means boot CPU only.
2139
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 sim710= [SCSI,HW]
2141 See header of drivers/scsi/sim710.c.
2142
2143 simeth= [IA-64]
2144 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 slram= [HW,MTD]
2147
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002148 slub_debug[=options[,slabs]] [MM, SLUB]
2149 Enabling slub_debug allows one to determine the
2150 culprit if slab objects become corrupted. Enabling
2151 slub_debug can create guard zones around objects and
2152 may poison objects when not in use. Also tracks the
2153 last alloc / free. For more information see
2154 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002155
2156 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002157 Determines the maximum allowed order for slabs.
2158 A high setting may cause OOMs due to memory
2159 fragmentation. For more information see
2160 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002161
2162 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002163 The minimum number of objects per slab. SLUB will
2164 increase the slab order up to slub_max_order to
2165 generate a sufficiently large slab able to contain
2166 the number of objects indicated. The higher the number
2167 of objects the smaller the overhead of tracking slabs
2168 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002169 For more information see Documentation/vm/slub.txt.
2170
2171 slub_min_order= [MM, SLUB]
2172 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002173 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002174 For more information see Documentation/vm/slub.txt.
2175
2176 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002177 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002178 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002179 allocs to different slabs. Debug options disable
2180 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002181 For more information see Documentation/vm/slub.txt.
2182
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 smart2= [HW]
2184 Format: <io1>[,<io2>[,...,<io8>]]
2185
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002186 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002187 attempt to substitute SMP alternatives once at boot.
2188
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002189 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2190 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2191 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2192 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2193 smsc-ircc2.ircc_irq= [HW] IRQ line
2194 smsc-ircc2.ircc_dma= [HW] DMA channel
2195 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2196 0: Toshiba Satellite 1800 (GP data pin select)
2197 1: Fast pin select (default)
2198 2: ATC IRMode
2199
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200 snd-ad1816a= [HW,ALSA]
2201
2202 snd-ad1848= [HW,ALSA]
2203
2204 snd-ali5451= [HW,ALSA]
2205
2206 snd-als100= [HW,ALSA]
2207
2208 snd-als4000= [HW,ALSA]
2209
2210 snd-azt2320= [HW,ALSA]
2211
2212 snd-cmi8330= [HW,ALSA]
2213
2214 snd-cmipci= [HW,ALSA]
2215
2216 snd-cs4231= [HW,ALSA]
2217
2218 snd-cs4232= [HW,ALSA]
2219
2220 snd-cs4236= [HW,ALSA]
2221
2222 snd-cs4281= [HW,ALSA]
2223
2224 snd-cs46xx= [HW,ALSA]
2225
2226 snd-dt019x= [HW,ALSA]
2227
2228 snd-dummy= [HW,ALSA]
2229
2230 snd-emu10k1= [HW,ALSA]
2231
2232 snd-ens1370= [HW,ALSA]
2233
2234 snd-ens1371= [HW,ALSA]
2235
2236 snd-es968= [HW,ALSA]
2237
2238 snd-es1688= [HW,ALSA]
2239
2240 snd-es18xx= [HW,ALSA]
2241
2242 snd-es1938= [HW,ALSA]
2243
2244 snd-es1968= [HW,ALSA]
2245
2246 snd-fm801= [HW,ALSA]
2247
2248 snd-gusclassic= [HW,ALSA]
2249
2250 snd-gusextreme= [HW,ALSA]
2251
2252 snd-gusmax= [HW,ALSA]
2253
2254 snd-hdsp= [HW,ALSA]
2255
2256 snd-ice1712= [HW,ALSA]
2257
2258 snd-intel8x0= [HW,ALSA]
2259
2260 snd-interwave= [HW,ALSA]
2261
2262 snd-interwave-stb=
2263 [HW,ALSA]
2264
2265 snd-korg1212= [HW,ALSA]
2266
2267 snd-maestro3= [HW,ALSA]
2268
2269 snd-mpu401= [HW,ALSA]
2270
2271 snd-mtpav= [HW,ALSA]
2272
2273 snd-nm256= [HW,ALSA]
2274
2275 snd-opl3sa2= [HW,ALSA]
2276
2277 snd-opti92x-ad1848=
2278 [HW,ALSA]
2279
2280 snd-opti92x-cs4231=
2281 [HW,ALSA]
2282
2283 snd-opti93x= [HW,ALSA]
2284
2285 snd-pmac= [HW,ALSA]
2286
2287 snd-rme32= [HW,ALSA]
2288
2289 snd-rme96= [HW,ALSA]
2290
2291 snd-rme9652= [HW,ALSA]
2292
2293 snd-sb8= [HW,ALSA]
2294
2295 snd-sb16= [HW,ALSA]
2296
2297 snd-sbawe= [HW,ALSA]
2298
2299 snd-serial= [HW,ALSA]
2300
2301 snd-sgalaxy= [HW,ALSA]
2302
2303 snd-sonicvibes= [HW,ALSA]
2304
2305 snd-sun-amd7930=
2306 [HW,ALSA]
2307
2308 snd-sun-cs4231= [HW,ALSA]
2309
2310 snd-trident= [HW,ALSA]
2311
2312 snd-usb-audio= [HW,ALSA,USB]
2313
2314 snd-via82xx= [HW,ALSA]
2315
2316 snd-virmidi= [HW,ALSA]
2317
2318 snd-wavefront= [HW,ALSA]
2319
2320 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002321
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002322 softlockup_panic=
2323 [KNL] Should the soft-lockup detector generate panics.
2324
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2326 See Documentation/sonypi.txt
2327
2328 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002329 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002330
2331 spia_io_base= [HW,MTD]
2332 spia_fio_base=
2333 spia_pedr=
2334 spia_peddr=
2335
2336 sscape= [HW,OSS]
2337 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002338
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2340 See Documentation/scsi/st.txt.
2341
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002342 stacktrace [FTRACE]
2343 Enabled the stack tracer on boot up.
2344
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 sti= [PARISC,HW]
2346 Format: <num>
2347 Set the STI (builtin display/keyboard on the HP-PARISC
2348 machines) console (graphic card) which should be used
2349 as the initial boot-console.
2350 See also comment in drivers/video/console/sticore.c.
2351
2352 sti_font= [HW]
2353 See comment in drivers/video/console/sticore.c.
2354
2355 stifb= [HW]
2356 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2357
Greg Banks42a7fc42007-03-06 01:42:23 -08002358 sunrpc.pool_mode=
2359 [NFS]
2360 Control how the NFS server code allocates CPUs to
2361 service thread pools. Depending on how many NICs
2362 you have and where their interrupts are bound, this
2363 option will affect which CPUs will do NFS serving.
2364 Note: this parameter cannot be changed while the
2365 NFS server is running.
2366
2367 auto the server chooses an appropriate mode
2368 automatically using heuristics
2369 global a single global pool contains all CPUs
2370 percpu one pool for each CPU
2371 pernode one pool for each NUMA node (equivalent
2372 to global on non-NUMA machines)
2373
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002375
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 switches= [HW,M68k]
2377
2378 sym53c416= [HW,SCSI]
2379 See header of drivers/scsi/sym53c416.c.
2380
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002381 sysrq_always_enabled
2382 [KNL]
2383 Ignore sysrq setting - this boot parameter will
2384 neutralize any effect of /proc/sys/kernel/sysrq.
2385 Useful for debugging.
2386
Linus Torvalds1da177e2005-04-16 15:20:36 -07002387 t128= [HW,SCSI]
2388 See header of drivers/scsi/t128.c.
2389
2390 tdfx= [HW,DRM]
2391
David Brownell77437fd2008-07-23 21:28:33 -07002392 test_suspend= [SUSPEND]
2393 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2394 standby suspend) as the system sleep state to briefly
2395 enter during system startup. The system is woken from
2396 this state using a wakeup-capable RTC alarm.
2397
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398 thash_entries= [KNL,NET]
2399 Set number of hash buckets for TCP connection
2400
Len Brownf8707ec2007-08-12 00:12:54 -04002401 thermal.act= [HW,ACPI]
2402 -1: disable all active trip points in all thermal zones
2403 <degrees C>: override all lowest active trip points
2404
Len Brownc52a7412007-08-14 15:49:32 -04002405 thermal.crt= [HW,ACPI]
2406 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002407 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002408
Len Brownf5487142007-08-12 00:12:44 -04002409 thermal.nocrt= [HW,ACPI]
2410 Set to disable actions on ACPI thermal zone
2411 critical and hot trip points.
2412
Len Brown72b33ef2007-08-12 00:12:17 -04002413 thermal.off= [HW,ACPI]
2414 1: disable ACPI thermal control
2415
Len Browna70cdc52007-08-12 00:12:35 -04002416 thermal.psv= [HW,ACPI]
2417 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002418 <degrees C>: override all passive trip points to this
2419 value
Len Browna70cdc52007-08-12 00:12:35 -04002420
Len Brown730ff342007-08-12 00:12:26 -04002421 thermal.tzp= [HW,ACPI]
2422 Specify global default ACPI thermal zone polling rate
2423 <deci-seconds>: poll all this frequency
2424 0: no polling (default)
2425
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 tmscsim= [HW,SCSI]
2427 See comment before function dc390_setup() in
2428 drivers/scsi/tmscsim.c.
2429
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002430 topology= [S390]
2431 Format: {off | on}
2432 Specify if the kernel should make use of the cpu
2433 topology informations if the hardware supports these.
2434 The scheduler will make use of these informations and
2435 e.g. base its process migration decisions on it.
2436 Default is off.
2437
Linus Torvalds1da177e2005-04-16 15:20:36 -07002438 tp720= [HW,PS2]
2439
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002440 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2441
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002443 Format:
2444 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2445
Alok Kataria395628e2008-10-24 17:22:01 -07002446 tsc= Disable clocksource-must-verify flag for TSC.
2447 Format: <string>
2448 [x86] reliable: mark tsc clocksource as reliable, this
2449 disables clocksource verification at runtime.
2450 Used to enable high-resolution timer mode on older
2451 hardware, and in virtualized environment.
2452
Randy Dunlapa9913042005-10-23 12:57:11 -07002453 turbografx.map[2|3]= [HW,JOY]
2454 TurboGraFX parallel port interface
2455 Format:
2456 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 See also Documentation/input/joystick-parport.txt
2458
2459 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2460 See header of drivers/scsi/u14-34f.c.
2461
2462 uart401= [HW,OSS]
2463 Format: <io>,<irq>
2464
2465 uart6850= [HW,OSS]
2466 Format: <io>,<irq>
2467
Alan Stern5f8364b2006-12-05 16:29:55 -05002468 uhci-hcd.ignore_oc=
2469 [USB] Ignore overcurrent events (default N).
2470 Some badly-designed motherboards generate lots of
2471 bogus events, for ports that aren't wired to
2472 anything. Set this parameter to avoid log spamming.
2473 Note that genuine overcurrent events won't be
2474 reported either.
2475
Simon Arlotte3a61b02008-07-19 23:32:54 +01002476 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302477 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002478 Set unknown_nmi_panic=1 early on boot.
2479
Alan Sternb5e795f2007-02-20 15:00:53 -05002480 usbcore.autosuspend=
2481 [USB] The autosuspend time delay (in seconds) used
2482 for newly-detected USB devices (default 2). This
2483 is the time required before an idle device will be
2484 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002485 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002486
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002487 usbcore.usbfs_snoop=
2488 [USB] Set to log all usbfs traffic (default 0 = off).
2489
2490 usbcore.blinkenlights=
2491 [USB] Set to cycle leds on hubs (default 0 = off).
2492
2493 usbcore.old_scheme_first=
2494 [USB] Start with the old device initialization
2495 scheme (default 0 = off).
2496
2497 usbcore.use_both_schemes=
2498 [USB] Try the other device initialization scheme
2499 if the first one fails (default 1 = enabled).
2500
2501 usbcore.initial_descriptor_timeout=
2502 [USB] Specifies timeout for the initial 64-byte
2503 USB_REQ_GET_DESCRIPTOR request in milliseconds
2504 (default 5000 = 5.0 seconds).
2505
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506 usbhid.mousepoll=
2507 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002508
Alan Sternd4f373e2008-11-10 14:07:45 -05002509 usb-storage.delay_use=
2510 [UMS] The delay in seconds before a new device is
2511 scanned for Logical Units (default 5).
2512
2513 usb-storage.quirks=
2514 [UMS] A list of quirks entries to supplement or
2515 override the built-in unusual_devs list. List
2516 entries are separated by commas. Each entry has
2517 the form VID:PID:Flags where VID and PID are Vendor
2518 and Product ID values (4-digit hex numbers) and
2519 Flags is a set of characters, each corresponding
2520 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002521 a = SANE_SENSE (collect more than 18 bytes
2522 of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002523 c = FIX_CAPACITY (decrease the reported
2524 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002525 h = CAPACITY_HEURISTICS (decrease the
2526 reported device capacity by one
2527 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002528 i = IGNORE_DEVICE (don't bind to this
2529 device);
2530 l = NOT_LOCKABLE (don't try to lock and
2531 unlock ejectable media);
2532 m = MAX_SECTORS_64 (don't transfer more
2533 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002534 o = CAPACITY_OK (accept the capacity
2535 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002536 r = IGNORE_RESIDUE (the device reports
2537 bogus residue values);
2538 s = SINGLE_LUN (the device has only one
2539 Logical Unit);
2540 w = NO_WP_DETECT (don't test whether the
2541 medium is write-protected).
2542 Example: quirks=0419:aaf5:rl,0421:0433:rc
2543
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302544 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002545 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002546 vdso=1: enable VDSO (default)
2547 vdso=0: disable VDSO mapping
2548
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302549 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002550 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2551 vdso32=1: enable 32-bit VDSO (default)
2552 vdso32=0: disable 32-bit VDSO mapping
2553
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002554 vector= [IA-64,SMP]
2555 vector=percpu: enable percpu vector domain
2556
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 video= [FB] Frame buffer configuration
2558 See Documentation/fb/modedb.txt.
2559
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002560 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002561 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002562 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002563 Use vga=ask for menu.
2564 This is actually a boot loader parameter; the value is
2565 passed to the kernel using a special protocol.
2566
Randy Dunlapa9913042005-10-23 12:57:11 -07002567 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 size of <nn>. This can be used to increase the
2569 minimum size (128MB on x86). It can also be used to
2570 decrease the size and leave more room for directly
2571 mapped kernel RAM.
2572
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002573 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2574 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002575
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002576 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2577 Format: <command>
2578
2579 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2580 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002581
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002582 vt.default_blu= [VT]
2583 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2584 Change the default blue palette of the console.
2585 This is a 16-member array composed of values
2586 ranging from 0-255.
2587
2588 vt.default_grn= [VT]
2589 Format: <green0>,<green1>,<green2>,...,<green15>
2590 Change the default green palette of the console.
2591 This is a 16-member array composed of values
2592 ranging from 0-255.
2593
2594 vt.default_red= [VT]
2595 Format: <red0>,<red1>,<red2>,...,<red15>
2596 Change the default red palette of the console.
2597 This is a 16-member array composed of values
2598 ranging from 0-255.
2599
2600 vt.default_utf8=
2601 [VT]
2602 Format=<0|1>
2603 Set system-wide default UTF-8 mode for all tty's.
2604 Default is 1, i.e. UTF-8 mode is enabled for all
2605 newly opened terminals.
2606
Linus Torvalds1da177e2005-04-16 15:20:36 -07002607 waveartist= [HW,OSS]
2608 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002609
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610 wd33c93= [HW,SCSI]
2611 See header of drivers/scsi/wd33c93.c.
2612
2613 wd7000= [HW,SCSI]
2614 See header of drivers/scsi/wd7000.c.
2615
2616 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002617 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002619 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2620 default x2apic cluster mode on platforms
2621 supporting x2apic.
2622
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2624 xd_geo= See header of drivers/block/xd.c.
2625
2626 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002627 Format:
2628 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629
Randy Dunlapa9913042005-10-23 12:57:11 -07002630______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631
2632TODO:
2633
2634 Add documentation for ALSA options.
2635 Add more DRM drivers.