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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
890 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
891 .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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100895 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700897 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
898 Claim all unknown PCI IDE storage controllers.
899
Andi Kleenf039b752007-05-02 19:27:12 +0200900 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800901 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
902 Poll forces a polling idle loop that can slightly
903 improve the performance of waking up a idle CPU, but
904 will use a lot of power and make the system run hot.
905 Not recommended.
906 idle=mwait: On systems which support MONITOR/MWAIT but
907 the kernel chose to not use it because it doesn't save
908 as much power as a normal idle loop, use the
909 MONITOR/MWAIT idle loop anyways. Performance should be
910 the same as idle=poll.
911 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800912 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800913 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700914
Ingo Molnar792908222006-12-06 20:40:51 -0800915 ignore_loglevel [KNL]
916 Ignore loglevel setting - this will print /all/
917 kernel messages to the console. Useful for debugging.
918
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 ihash_entries= [KNL]
920 Set number of hash buckets for inode cache.
921
Mimi Zohar3323eec2009-02-04 09:06:58 -0500922 ima_audit= [IMA]
923 Format: { "0" | "1" }
924 0 -- integrity auditing messages. (Default)
925 1 -- enable informational integrity auditing messages.
926
927 ima_hash= [IMA]
928 Formt: { "sha1" | "md5" }
929 default: "sha1"
930
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 in2000= [HW,SCSI]
932 See header of drivers/scsi/in2000.c.
933
934 init= [KNL]
935 Format: <full_path>
936 Run specified binary instead of /sbin/init as init
937 process.
938
939 initcall_debug [KNL] Trace initcalls as they are executed. Useful
940 for working out where the kernel is dying during
941 startup.
942
943 initrd= [BOOT] Specify the location of the initial ramdisk
944
945 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
946 Format: <irq>
947
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700948 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800949 on
950 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700951 off
952 Disable intel iommu driver.
953 igfx_off [Default Off]
954 By default, gfx is mapped as normal device. If a gfx
955 device has a dedicated DMAR unit, the DMAR unit is
956 bypassed by not enabling DMAR with this option. In
957 this case, gfx device will use physical address for
958 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700959 forcedac [x86_64]
960 With this option iommu will not optimize to look
961 for io virtual address below 32 bit forcing dual
962 address cycle on pci bus for cards supporting greater
963 than 32 bit addressing. The default is to look
964 for translation below 32 bit and if not available
965 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800966 strict [Default Off]
967 With this option on every unmap_single operation will
968 result in a hardware IOTLB flush operation as opposed
969 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700970
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700971 inttest= [IA64]
972
973 iomem= Disable strict checking of access to MMIO memory
974 strict regions from userspace.
975 relaxed
976
977 iommu= [x86]
978 off
979 force
980 noforce
981 biomerge
982 panic
983 nopanic
984 merge
985 nomerge
986 forcesac
987 soft
988
989 io7= [HW] IO7 for Marvel based alpha systems
990 See comment before marvel_specify_io7 in
991 arch/alpha/kernel/core_marvel.c.
992
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530993 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100994 0x80
995 Standard port 0x80 based delay
996 0xed
997 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100998 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100999 Simple two microseconds delay
1000 none
1001 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001002
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001004 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
1006 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001007 See comment before ip2_setup() in
1008 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009
1010 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1011 See header of drivers/scsi/ips.c.
1012
Alan Cox200803d2005-06-28 20:45:18 -07001013 irqfixup [HW]
1014 When an interrupt is not handled search all handlers
1015 for it. Intended to get systems with badly broken
1016 firmware running.
1017
1018 irqpoll [HW]
1019 When an interrupt is not handled search all handlers
1020 for it. Also check all handlers each timer
1021 interrupt. Intended to get systems with badly broken
1022 firmware running.
1023
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001025 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026
1027 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001028 Format:
1029 <cpu number>,...,<cpu number>
1030 or
Li Zefanb225d442008-11-06 12:53:39 -08001031 <cpu number>-<cpu number>
1032 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001033 or a mixture
1034 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001035
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 This option can be used to specify one or more CPUs
1037 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001038 algorithms. You can move a process onto or off an
1039 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 <cpu number> begins at 0 and the maximum value is
1041 "number of CPUs in system - 1".
1042
1043 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001044 alternative -- manually setting the CPU mask of all
1045 tasks in the system -- can cause problems and
1046 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047
Randy Dunlapa9913042005-10-23 12:57:11 -07001048 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049
1050 js= [HW,JOY] Analog joystick
1051 See Documentation/input/joystick.txt.
1052
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001053 keepinitrd [HW,ARM]
1054
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301055 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001056 specifies the amount of memory usable by the kernel
1057 for non-movable allocations. The requested amount is
1058 spread evenly throughout all nodes in the system. The
1059 remaining memory in each node is used for Movable
1060 pages. In the event, a node is too small to have both
1061 kernelcore and Movable pages, kernelcore pages will
1062 take priority and other nodes will have a larger number
1063 of kernelcore pages. The Movable zone is used for the
1064 allocation of pages that may be reclaimed or moved
1065 by the page migration subsystem. This means that
1066 HugeTLB pages may not be allocated from this zone.
1067 Note that allocations like PTEs-from-HighMem still
1068 use the HighMem zone if it exists, and the Normal
1069 zone if it does not.
1070
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001071 kgdboc= [HW] kgdb over consoles.
1072 Requires a tty driver that supports console polling.
1073 (only serial suported for now)
1074 Format: <serial_device>[,baud]
1075
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001076 kmac= [MIPS] korina ethernet MAC address.
1077 Configure the RouterBoard 532 series on-chip
1078 Ethernet adapter MAC address.
1079
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301080 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001081 in oops dumps.
1082
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 l2cr= [PPC]
1084
Robert Brosea78bfbf2008-03-29 07:20:23 +11001085 l3cr= [PPC]
1086
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001087 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001088 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301090 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001091 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001092
FD Camifcb71f62008-01-06 19:08:56 +01001093 libata.dma= [LIBATA] DMA control
1094 libata.dma=0 Disable all PATA and SATA DMA
1095 libata.dma=1 PATA and SATA Disk DMA only
1096 libata.dma=2 ATAPI (CDROM) DMA only
1097 libata.dma=4 Compact Flash DMA only
1098 Combinations also work, so libata.dma=3 enables DMA
1099 for disks and CDROMs, but not CFs.
1100
Dave Jones78e70c22007-09-27 11:50:13 -04001101 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1102 when set.
1103 Format: <int>
1104
Tejun Heo33267322008-02-13 09:15:09 +09001105 libata.force= [LIBATA] Force configurations. The format is comma
1106 separated list of "[ID:]VAL" where ID is
1107 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1108 matching port, link or device. Basically, it matches
1109 the ATA ID string printed on console by libata. If
1110 the whole ID part is omitted, the last PORT and DEVICE
1111 values are used. If ID hasn't been specified yet, the
1112 configuration applies to all ports, links and devices.
1113
1114 If only DEVICE is omitted, the parameter applies to
1115 the port and all links and devices behind it. DEVICE
1116 number of 0 either selects the first device or the
1117 first fan-out link behind PMP device. It does not
1118 select the host link. DEVICE number of 15 selects the
1119 host link and device attached to it.
1120
1121 The VAL specifies the configuration to force. As long
1122 as there's no ambiguity shortcut notation is allowed.
1123 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1124 The following configurations can be forced.
1125
1126 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1127 Any ID with matching PORT is used.
1128
1129 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1130
1131 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1132 udma[/][16,25,33,44,66,100,133] notation is also
1133 allowed.
1134
1135 * [no]ncq: Turn on or off NCQ.
1136
Tejun Heo05944bd2008-08-13 20:19:09 +09001137 * nohrst, nosrst, norst: suppress hard, soft
1138 and both resets.
1139
Tejun Heo33267322008-02-13 09:15:09 +09001140 If there are multiple matching configurations changing
1141 the same attribute, the last one is used.
1142
Randy Dunlap7c4be252009-01-06 14:42:44 -08001143 lmb=debug [KNL] Enable lmb debug messages.
1144
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001146 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001148 lockd.nlm_grace_period=P [NFS] Assign grace period.
1149 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001151 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1152 Format: <integer>
1153
1154 lockd.nlm_timeout=T [NFS] Assign timeout value.
1155 Format: <integer>
1156
1157 lockd.nlm_udpport=M [NFS] Assign UDP port.
1158 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159
1160 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1161 Format: <irq>
1162
1163 loglevel= All Kernel Messages with a loglevel smaller than the
1164 console loglevel will be printed to the console. It can
1165 also be changed with klogd or other programs. The
1166 loglevels are defined as follows:
1167
1168 0 (KERN_EMERG) system is unusable
1169 1 (KERN_ALERT) action must be taken immediately
1170 2 (KERN_CRIT) critical conditions
1171 3 (KERN_ERR) error conditions
1172 4 (KERN_WARNING) warning conditions
1173 5 (KERN_NOTICE) normal but significant condition
1174 6 (KERN_INFO) informational
1175 7 (KERN_DEBUG) debug-level messages
1176
1177 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001178 Format: { n | nk | nM }
1179 n must be a power of two. The default size
1180 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181
Randy Dunlapaccaa242007-10-16 01:29:37 -07001182 logo.nologo [FB] Disables display of the built-in Linux logo.
1183 This may be used to provide more screen space for
1184 kernel log messages and is useful when debugging
1185 kernel boot problems.
1186
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187 lp=0 [LP] Specify parallel ports to use, e.g,
1188 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1189 lp=reset first parallel port). 'lp=0' disables the
1190 lp=auto printer driver. 'lp=reset' (which can be
1191 specified in addition to the ports) causes
1192 attached printers to be reset. Using
1193 lp=port1,port2,... specifies the parallel ports
1194 to associate lp devices with, starting with
1195 lp0. A port specification may be 'none' to skip
1196 that lp device, or a parport name such as
1197 'parport0'. Specifying 'lp=auto' instead of a
1198 port specification list means that device IDs
1199 from each port should be examined, to see if
1200 an IEEE 1284-compliant printer is attached; if
1201 so, the driver will manage that printer.
1202 See also header of drivers/char/lp.c.
1203
1204 lpj=n [KNL]
1205 Sets loops_per_jiffy to given constant, thus avoiding
1206 time-consuming boot-time autodetection (up to 250 ms per
1207 CPU). 0 enables autodetection (default). To determine
1208 the correct value for your kernel, boot with normal
1209 autodetection and see what value is printed. Note that
1210 on SMP systems the preset will be applied to all CPUs,
1211 which is likely to cause problems if your CPUs need
1212 significantly divergent settings. An incorrect value
1213 will cause delays in the kernel to be wrong, leading to
1214 unpredictable I/O errors and other breakage. Although
1215 unlikely, in the extreme case this might damage your
1216 hardware.
1217
1218 ltpc= [NET]
1219 Format: <io>,<irq>,<dma>
1220
Randy Dunlapa9913042005-10-23 12:57:11 -07001221 mac5380= [HW,SCSI] Format:
1222 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223
Randy Dunlapa9913042005-10-23 12:57:11 -07001224 machvec= [IA64] Force the use of a particular machine-vector
1225 (machvec) in a generic kernel.
1226 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001228 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1229 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
1231 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001232 should make use of. maxcpus=n : n >= 0 limits the
1233 kernel to using 'n' processors. n=0 is a special case,
1234 it is equivalent to "nosmp", which also disables
1235 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001237 max_loop= [LOOP] Maximum number of loopback devices that can
1238 be mounted
1239 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001240
Randy Dunlapa9913042005-10-23 12:57:11 -07001241 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 Should be between 1 and 2^32-1.
1243
1244 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001245 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 Should be between 1 and 16384.
1247
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 mcatest= [IA-64]
1249
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001250 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251
Uwe Hermann71cced62008-10-20 09:32:21 -07001252 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001253
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 md= [HW] RAID subsystems devices and level
1255 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001256
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 mdacon= [MDA]
1258 Format: <first>,<last>
1259 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001260
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1262 Amount of memory to be used when the kernel is not able
1263 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001264 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 address space collisions. Without memmap= PCI devices
1266 could be placed at addresses belonging to unused RAM.
1267
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001268 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 memory.
1270
Paul Mundt6902aa82008-09-21 17:14:42 +09001271 memchunk=nn[KMG]
1272 [KNL,SH] Allow user to override the default size for
1273 per-device physically contiguous DMA buffers.
1274
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301275 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 E820 memory map, as specified by the user.
1277 Such memmap=exactmap lines can be constructed based on
1278 BIOS output or other requirements. See the memmap=nn@ss
1279 option description.
1280
1281 memmap=nn[KMG]@ss[KMG]
1282 [KNL] Force usage of a specific region of memory
1283 Region of memory to be used, from ss to ss+nn.
1284
1285 memmap=nn[KMG]#ss[KMG]
1286 [KNL,ACPI] Mark specific memory as ACPI data.
1287 Region of memory to be used, from ss to ss+nn.
1288
1289 memmap=nn[KMG]$ss[KMG]
1290 [KNL,ACPI] Mark specific memory as reserved.
1291 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001292 Example: Exclude memory from 0x18690000-0x1869ffff
1293 memmap=64K$0x18690000
1294 or
1295 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001297 memory_corruption_check=0/1 [X86]
1298 Some BIOSes seem to corrupt the first 64k of
1299 memory when doing things like suspend/resume.
1300 Setting this option will scan the memory
1301 looking for corruption. Enabling this will
1302 both detect corruption and prevent the kernel
1303 from using the memory being corrupted.
1304 However, its intended as a diagnostic tool; if
1305 repeatable BIOS-originated corruption always
1306 affects the same memory, you can use memmap=
1307 to prevent the kernel from using that memory.
1308
1309 memory_corruption_check_size=size [X86]
1310 By default it checks for corruption in the low
1311 64k, making this memory unavailable for normal
1312 use. Use this parameter to scan for
1313 corruption in more or less memory.
1314
1315 memory_corruption_check_period=seconds [X86]
1316 By default it checks for corruption every 60
1317 seconds. Use this parameter to check at some
1318 other rate. 0 disables periodic checking.
1319
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001320 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001321 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001322 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001323 Specifies the number of memtest passes to be
1324 performed. Each pass selects another test
1325 pattern from a given set of patterns. Memtest
1326 fills the memory with this pattern, validates
1327 memory contents and reserves bad memory
1328 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001329
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330 meye.*= [HW] Set MotionEye Camera parameters
1331 See Documentation/video4linux/meye.txt.
1332
Andres Salomon8f368812007-10-12 23:04:06 +02001333 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1334 Multi-Function General Purpose Timers on AMD Geode
1335 platforms.
1336
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001337 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1338 the BIOS has incorrectly applied a workaround. TinyBIOS
1339 version 0.98 is known to be affected, 0.99 fixes the
1340 problem by letting the user disable the workaround.
1341
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 mga= [HW,DRM]
1343
Randy Dunlap1c207f92008-11-19 15:36:16 -08001344 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1345 physical address is ignored.
1346
Mel Gorman6b74ab92008-07-23 21:26:49 -07001347 mminit_loglevel=
1348 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1349 parameter allows control of the logging verbosity for
1350 the additional memory initialisation checks. A value
1351 of 0 disables mminit logging and a level of 4 will
1352 log everything. Information is printed at KERN_DEBUG
1353 so loglevel=8 may also need to be specified.
1354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 mousedev.tap_time=
1356 [MOUSE] Maximum time between finger touching and
1357 leaving touchpad surface for touch to be considered
1358 a tap and be reported as a left button click (for
1359 touchpads working in absolute mode only).
1360 Format: <msecs>
1361 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1362 reporting absolute coordinates, such as tablets
1363 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1364 reporting absolute coordinates, such as tablets
1365
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301366 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001367 is similar to kernelcore except it specifies the
1368 amount of memory used for migratable allocations.
1369 If both kernelcore and movablecore is specified,
1370 then kernelcore will be at *least* the specified
1371 value but may be more. If movablecore on its own
1372 is specified, the administrator must be careful
1373 that the amount of memory usable for all allocations
1374 is not too small.
1375
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 mpu401= [HW,OSS]
1377 Format: <io>,<irq>
1378
1379 MTD_Partition= [MTD]
1380 Format: <name>,<region-number>,<size>,<offset>
1381
Randy Dunlapa9913042005-10-23 12:57:11 -07001382 MTD_Region= [MTD] Format:
1383 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384
1385 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001386 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387
Ben Dooks9db829f2008-07-03 11:24:29 +01001388 mtdset= [ARM]
1389 ARM/S3C2412 JIVE boot control
1390
1391 See arch/arm/mach-s3c2412/mach-jive.c
1392
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001394 [HW] Make the MicroTouch USB driver use raw coordinates
1395 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001397 mtrr_chunk_size=nn[KMG] [X86]
1398 used for mtrr cleanup. It is largest continous chunk
1399 that could hold holes aka. UC entries.
1400
1401 mtrr_gran_size=nn[KMG] [X86]
1402 Used for mtrr cleanup. It is granularity of mtrr block.
1403 Default is 1.
1404 Large value could prevent small alignment from
1405 using up MTRRs.
1406
1407 mtrr_spare_reg_nr=n [X86]
1408 Format: <integer>
1409 Range: 0,7 : spare reg number
1410 Default : 1
1411 Used for mtrr cleanup. It is spare mtrr entries number.
1412 Set to 2 or more if your graphical card needs more.
1413
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1415
1416 NCR_D700= [HW,SCSI]
1417 See header of drivers/scsi/NCR_D700.c.
1418
1419 ncr5380= [HW,SCSI]
1420
1421 ncr53c400= [HW,SCSI]
1422
1423 ncr53c400a= [HW,SCSI]
1424
1425 ncr53c406a= [HW,SCSI]
1426
1427 ncr53c8xx= [HW,SCSI]
1428
1429 netdev= [NET] Network devices parameters
1430 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1431 Note that mem_start is often overloaded to mean
1432 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001433 This usage is only documented in each driver source
1434 file if at all.
1435
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001436 nf_conntrack.acct=
1437 [NETFILTER] Enable connection tracking flow accounting
1438 0 to disable accounting
1439 1 to enable accounting
1440 Default value depends on CONFIG_NF_CT_ACCT that is
1441 going to be removed in 2.6.29.
1442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001444 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445
1446 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001447 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
Trond Myklebusta72b4422006-01-03 09:55:41 +01001449 nfs.callback_tcpport=
1450 [NFS] set the TCP port on which the NFSv4 callback
1451 channel should listen.
1452
Trond Myklebust58df0952006-01-03 09:55:57 +01001453 nfs.idmap_cache_timeout=
1454 [NFS] set the maximum lifetime for idmapper cache
1455 entries.
1456
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001457 nfs.enable_ino64=
1458 [NFS] enable 64-bit inode numbers.
1459 If zero, the NFS client will fake up a 32-bit inode
1460 number for the readdir() and stat() syscalls instead
1461 of returning the full 64-bit number.
1462 The default is to return 64-bit inode numbers.
1463
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001464 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1465 when a NMI is triggered.
1466 Format: [state][,regs][,debounce][,die]
1467
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301468 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001469 Format: [panic,][num]
1470 Valid num: 0,1,2
1471 0 - turn nmi_watchdog off
1472 1 - use the IO-APIC timer for the NMI watchdog
1473 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001474 a performance counter. Note: This will use one
1475 performance counter and the local APIC's performance
1476 vector.
1477 When panic is specified, panic when an NMI watchdog
1478 timeout occurs.
1479 This is useful when you use a panic=... timeout and
1480 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001481 Instead of 1 and 2 it is possible to use the following
1482 symbolic names: lapic and ioapic
1483 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001485 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 emulation library even if a 387 maths coprocessor
1487 is present.
1488
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001489 no_console_suspend
1490 [HW] Never suspend the console
1491 Disable suspending of consoles during suspend and
1492 hibernate operations. Once disabled, debugging
1493 messages can reach various consoles while the rest
1494 of the system is being put to sleep (ie, while
1495 debugging driver suspend/resume hooks). This may
1496 not work reliably with all consoles, but is known
1497 to work with serial and VGA consoles.
1498
Christoph Lameterc1aee212007-05-31 00:40:47 -07001499 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1500 caches in the slab allocator. Saves per-node memory,
1501 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001502
Randy Dunlapa9913042005-10-23 12:57:11 -07001503 noalign [KNL,ARM]
1504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 noapic [SMP,APIC] Tells the kernel to not make use of any
1506 IOAPICs that may be present in the system.
1507
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 nobats [PPC] Do not use BATs for mapping kernel lowmem
1509 on "Classic" PPC cores.
1510
1511 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001512
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001513 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1514
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001515 nodelayacct [KNL] Disable per-task delay accounting
1516
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1518
Paul Mundt6902aa82008-09-21 17:14:42 +09001519 nodsp [SH] Disable hardware DSP at boot time.
1520
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301521 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001522
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 noexec [IA-64]
1524
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301525 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001526 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001528 noexec=off: disable non-executable mappings
1529
1530 noexec32 [X86-64]
1531 This affects only 32-bit executables.
1532 noexec32=on: enable non-executable mappings (default)
1533 read doesn't imply executable mappings
1534 noexec32=off: disable non-executable mappings
1535 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
Paul Mundt6902aa82008-09-21 17:14:42 +09001537 nofpu [SH] Disable hardware FPU at boot time.
1538
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001539 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001540 register save and restore. The kernel will only save
1541 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542
Suresh Siddha0c752a92009-05-22 12:17:45 -07001543 noxsave [BUGS=X86] Disables x86 extended register state save
1544 and restore using xsave. The kernel will fallback to
1545 enabling legacy floating-point and sse state.
1546
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001547 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1548 wfi(ARM) instruction doesn't work correctly and not to
1549 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001550
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001551 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 instruction doesn't work correctly and not to
1553 use it.
1554
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001555 no_file_caps Tells the kernel not to honor file capabilities. The
1556 only way then for a file to be executed with privilege
1557 is to be setuid root or executed by root.
1558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 nohalt [IA-64] Tells the kernel not to use the power saving
1560 function PAL_HALT_LIGHT when idle. This increases
1561 power-consumption. On the positive side, it reduces
1562 interrupt wake-up latency, which may improve performance
1563 in certain environments such as networked servers or
1564 real-time systems.
1565
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001566 nohz= [KNL] Boottime enable/disable dynamic ticks
1567 Valid arguments: on, off
1568 Default: on
1569
Paul Mundteeee7852009-04-02 12:31:16 +09001570 noiotrap [SH] Disables trapped I/O port accesses.
1571
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001572 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573 disable unhandled interrupt sources.
1574
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301575 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001576 broken timer IRQ sources.
1577
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 noisapnp [ISAPNP] Disables ISA PnP code.
1579
1580 noinitrd [RAM] Tells the kernel not to load any configured
1581 initial RAM disk.
1582
Weidong Han03ea8152009-04-17 16:42:15 +08001583 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1584 remapping.
1585
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 nointroute [IA-64]
1587
Tony Luck0aa366f2007-07-20 11:22:30 -07001588 nojitter [IA64] Disables jitter checking for ITC timers.
1589
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001590 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001592 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001593
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 noltlbs [PPC] Do not use large page/tlb entries for kernel
1595 lowmem mapping on PPC40x.
1596
Horms312f1f02006-02-22 09:57:55 +09001597 nomca [IA-64] Disable machine check abort handling
1598
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001599 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001600
Andres Salomon83d73842007-10-12 23:04:06 +02001601 nomfgpt [X86-32] Disable Multi-Function General Purpose
1602 Timer usage (for AMD Geode machines).
1603
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001604 norandmaps Don't use address space randomization. Equivalent to
1605 echo 0 > /proc/sys/kernel/randomize_va_space
1606
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001607 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001608
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001609 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001610 with UP alternatives
1611
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 noresidual [PPC] Don't use residual data on PReP machines.
1613
Randy Dunlapa9913042005-10-23 12:57:11 -07001614 noresume [SWSUSP] Disables resume and restores original swap
1615 space.
1616
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 no-scroll [VGA] Disables scrollback.
1618 This is required for the Braillex ib80-piezo Braille
1619 reader made by F.H. Papenmeier (Germany).
1620
1621 nosbagart [IA-64]
1622
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001623 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001624
Len Brown61ec7562007-08-16 03:34:22 -04001625 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1626 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627
Dave Jones97842212007-07-15 23:41:05 -07001628 nosoftlockup [KNL] Disable the soft-lockup detector.
1629
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001630 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001631 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001632
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 nosync [HW,M68K] Disables sync negotiation for all devices.
1634
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001635 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636
1637 nousb [USB] Disable the USB subsystem
1638
1639 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001640
Weidong Han2b2fd872009-04-17 16:42:12 +08001641 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1642
Fenghua Yua6c75b862008-03-14 13:57:08 -07001643 nptcg= [IA64] Override max number of concurrent global TLB
1644 purges which is reported from either PAL_VM_SUMMARY or
1645 SAL PALO.
1646
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001647 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1648
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001649 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1650 one of ['zone', 'node', 'default'] can be specified
1651 This can be set from sysctl after boot.
1652 See Documentation/sysctl/vm.txt for details.
1653
Randy Dunlap7c4be252009-01-06 14:42:44 -08001654 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1655 See Documentation/debugging-via-ohci1394.txt for more
1656 info.
1657
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001658 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1659 Rather than timing out after 20 ms if an EC
1660 command is not properly ACKed, override the length
1661 of the timeout. We have interrupts disabled while
1662 waiting for the ACK, so if this is set too high
1663 interrupts *may* be lost!
1664
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 opl3= [HW,OSS]
1666 Format: <io>
1667
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 oprofile.timer= [HW]
1669 Use timer interrupt instead of performance counters
1670
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001671 oprofile.cpu_type= Force an oprofile cpu type
1672 This might be useful if you have an older oprofile
1673 userland or if you want common events.
1674 Format: { archperfmon }
1675 archperfmon: [X86] Force use of architectural
1676 perfmon on Intel CPUs instead of the
1677 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001678
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 osst= [HW,SCSI] SCSI Tape Driver
1680 Format: <buffer_size>,<write_threshold>
1681 See also Documentation/scsi/st.txt.
1682
1683 panic= [KNL] Kernel behaviour on panic
1684 Format: <timeout>
1685
1686 parkbd.port= [HW] Parallel port number the keyboard adapter is
1687 connected to, default is 0.
1688 Format: <parport#>
1689 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1690 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001691 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692
Randy Dunlapa9913042005-10-23 12:57:11 -07001693 parport= [HW,PPT] Specify parallel ports. 0 disables.
1694 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1695 Use 'auto' to force the driver to use any
1696 IRQ/DMA settings detected (the default is to
1697 ignore detected IRQ/DMA settings because of
1698 possible conflicts). You can specify the base
1699 address, IRQ, and DMA settings; IRQ and DMA
1700 should be numbers, or 'auto' (for using detected
1701 settings on that particular port), or 'nofifo'
1702 (to avoid using a FIFO even if it is detected).
1703 Parallel ports are assigned in the order they
1704 are specified on the command line, starting
1705 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706
Randy Dunlapa9913042005-10-23 12:57:11 -07001707 parport_init_mode= [HW,PPT]
1708 Configure VIA parallel port to operate in
1709 a specific mode. This is necessary on Pegasos
1710 computer where firmware has no options for setting
1711 up parallel port mode and sets it to spp.
1712 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 Format: [spp|ps2|epp|ecp|ecpepp]
1714
Randy Dunlapa9913042005-10-23 12:57:11 -07001715 pas2= [HW,OSS] Format:
1716 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1717
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718 pas16= [HW,SCSI]
1719 See header of drivers/scsi/pas16.c.
1720
Andrew Mortondd287792006-03-23 03:00:57 -08001721 pause_on_oops=
1722 Halt all CPUs after the first oops has been printed for
1723 the specified number of seconds. This is to be used if
1724 your oopses keep scrolling off the screen.
1725
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 pcbit= [HW,ISDN]
1727
1728 pcd. [PARIDE]
1729 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001730 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731
Randy Dunlapa9913042005-10-23 12:57:11 -07001732 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001733 earlydump [X86] dump PCI config space before the kernel
1734 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001735 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001736 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001737 the hardware directly. Use this if your machine
1738 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001739 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001740 hardware access methods are allowed. Use this
1741 if you experience crashes upon bootup and you
1742 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001743 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001744 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001745 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001746 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001747 noaer [PCIE] If the PCIEAER kernel config parameter is
1748 enabled, this kernel boot option can be used to
1749 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001750 nodomains [PCI] Disable support for multiple PCI
1751 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301752 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001753 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001754 nomsi [MSI] If the PCI_MSI kernel config parameter is
1755 enabled, this kernel boot option can be used to
1756 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001757 noioapicquirk [APIC] Disable all boot interrupt quirks.
1758 Safety option to keep boot IRQs enabled. This
1759 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001760 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1761 primary IO-APIC for bridges that cannot disable
1762 boot IRQs. This fixes a source of spurious IRQs
1763 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001764 noioapicreroute [APIC] Disable workaround that uses the
1765 boot IRQ equivalent of an IRQ that connects to
1766 a chipset where boot IRQs cannot be disabled.
1767 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001768 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001769 routing table. These calls are known to be buggy
1770 on several machines and they hang the machine
1771 when used, but on other computers it's the only
1772 way to get the interrupt routing table. Try
1773 this option if the kernel is unable to allocate
1774 IRQs or discover secondary PCI buses on your
1775 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001776 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001777 Use with caution as certain devices share
1778 address decoders between ROMs and other
1779 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001780 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001781 expansion ROMs that do not already have
1782 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001783 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001784 assigned automatically to PCI devices. You can
1785 make the kernel exclude IRQs of your ISA cards
1786 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001787 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001788 of the PIRQ table (normally generated
1789 by the BIOS) if it is outside the
1790 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001791 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001792 useful if the kernel is unable to find your
1793 secondary buses and you want to tell it
1794 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001795 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001796 numbers ourselves, overriding
1797 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001798 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001799 in the BIOS $PIR table. This is needed on
1800 some systems with broken BIOSes, notably
1801 some HP Pavilion N5400 and Omnibook XE3
1802 notebooks. This will have no effect if ACPI
1803 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001804 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001805 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001806 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001807 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001808 routeirq Do IRQ routing for all PCI devices.
1809 This is normally done in pci_enable_device(),
1810 so this option is a temporary workaround
1811 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001812 skip_isa_align [X86] do not align io start addr, so can
1813 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001814 firmware [ARM] Do not re-enumerate the bus but instead
1815 just use the configuration from the
1816 bootloader. This is currently used on
1817 IXP2000 systems where the bus has to be
1818 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001819 noearly [X86] Don't do any early type 1 scanning.
1820 This might help on some broken boards which
1821 machine check when some devices' config space
1822 is read. But various workarounds are disabled
1823 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001824 bfsort Sort PCI devices into breadth-first order.
1825 This sorting is done to get a device
1826 order compatible with older (<= 2.4) kernels.
1827 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001828 cbiosize=nn[KMG] The fixed amount of bus space which is
1829 reserved for the CardBus bridge's IO window.
1830 The default value is 256 bytes.
1831 cbmemsize=nn[KMG] The fixed amount of bus space which is
1832 reserved for the CardBus bridge's memory
1833 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09001834 resource_alignment=
1835 Format:
1836 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1837 Specifies alignment and device to reassign
1838 aligned memory resources.
1839 If <order of align> is not specified,
1840 PAGE_SIZE is used as alignment.
1841 PCI-PCI bridge can be specified, if resource
1842 windows need to be expanded.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001843
Chuck Ebberte5665a42008-09-24 20:40:34 -04001844 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1845 Management.
1846 off Disable ASPM.
1847 force Enable ASPM even on devices that claim not to support it.
1848 WARNING: Forcing ASPM on may cause system lockups.
1849
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850 pcmv= [HW,PCMCIA] BadgePAD 4
1851
1852 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001853 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854
1855 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1856 boot time.
1857 Format: { 0 | 1 }
1858 See arch/parisc/kernel/pdc_chassis.c
1859
1860 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001861 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862
1863 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001864 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865
1866 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001867 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868
1869 plip= [PPT,NET] Parallel port network link
1870 Format: { parport<nr> | timid | 0 }
1871 See also Documentation/parport.txt.
1872
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001873 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1874 Override pmtimer IOPort with a hex value.
1875 e.g. pmtmr=0x508
1876
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001877 pnp.debug [PNP]
1878 Enable PNP debug messages. This depends on the
1879 CONFIG_PNP_DEBUG_MESSAGES option.
1880
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881 pnpacpi= [ACPI]
1882 { off }
1883
1884 pnpbios= [ISAPNP]
1885 { on | off | curr | res | no-curr | no-res }
1886
1887 pnp_reserve_irq=
1888 [ISAPNP] Exclude IRQs for the autoconfiguration
1889
1890 pnp_reserve_dma=
1891 [ISAPNP] Exclude DMAs for the autoconfiguration
1892
1893 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001894 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895
1896 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001897 [ISAPNP] Exclude memory regions for the
1898 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 Ranges are in pairs (memory base and size).
1900
Randy Dunlap4af94f32009-04-17 18:30:28 -07001901 ports= [IP_VS_FTP] IPVS ftp helper module
1902 Default is 21.
1903 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1904 may be specified.
1905 Format: <port>,<port>....
1906
Ingo Molnar45807a12007-07-15 23:40:10 -07001907 print-fatal-signals=
1908 [KNL] debug: print fatal signals
1909 print-fatal-signals=1: print segfault info to
1910 the kernel console.
1911 default: off.
1912
Randy Dunlape84845c2007-07-15 23:40:25 -07001913 printk.time= Show timing data prefixed to each printk message line
1914 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1915
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001916 processor.max_cstate= [HW,ACPI]
1917 Limit processor to maximum C-state
1918 max_cstate=9 overrides any DMI blacklist limit.
1919
1920 processor.nocst [HW,ACPI]
1921 Ignore the _CST method to determine C-states,
1922 instead using the legacy FADT method
1923
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001925 Format: [schedule,]<number>
1926 Param: "schedule" - profile schedule points.
1927 Param: <number> - step/bucket size as a power of 2 for
1928 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001929 Param: "sleep" - profile D-state sleeping (millisecs).
1930 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001931 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1934 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001935 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936
Randy Dunlapa9913042005-10-23 12:57:11 -07001937 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1938 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1940 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001941 psmouse.resetafter= [HW,MOUSE]
1942 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 (0 = never).
1944 psmouse.resolution=
1945 [HW,MOUSE] Set desired mouse resolution, in dpi.
1946 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001947 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 0 = disabled, 1 = enabled (default).
1949
1950 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001951 Format:
1952 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953
1954 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001955 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956
Kay Sieversdc8c8582007-08-15 12:25:38 +02001957 pty.legacy_count=
1958 [KNL] Number of legacy pty's. Overwrites compiled-in
1959 default number.
1960
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001961 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001962
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 r128= [HW,DRM]
1964
1965 raid= [HW,RAID]
1966 See Documentation/md.txt.
1967
Randy Dunlapa9913042005-10-23 12:57:11 -07001968 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001969 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001970
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001972 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001974 rcupdate.blimit= [KNL,BOOT]
1975 Set maximum number of finished RCU callbacks to process
1976 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001977
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001978 rcupdate.qhimark= [KNL,BOOT]
1979 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001980 RCU callbacks over which batch limiting is disabled.
1981
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001982 rcupdate.qlowmark= [KNL,BOOT]
1983 Set threshold of queued RCU callbacks below which
1984 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001985
Olof Johanssonffdfc402005-09-06 15:17:19 -07001986 rdinit= [KNL]
1987 Format: <full_path>
1988 Run specified binary instead of /init from the ramdisk,
1989 used for early userspace startup. See initrd.
1990
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001991 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08001993 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994
Paul Jackson46b6d942008-07-04 10:00:09 -07001995 relax_domain_level=
1996 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001997 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07001998
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2000
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002001 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002002 Format: nn[KMG]
2003 Reserves a hole at the top of the kernel virtual
2004 address space.
2005
Vivek Goyal7e962872006-09-27 01:50:44 -07002006 reset_devices [KNL] Force drivers to reset the underlying device
2007 during initialization.
2008
Randy Dunlapa9913042005-10-23 12:57:11 -07002009 resume= [SWSUSP]
2010 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002012 resume_offset= [SWSUSP]
2013 Specify the offset from the beginning of the partition
2014 given by "resume=" at which the swap header is located,
2015 in <PAGE_SIZE> units (needed only for swap files).
2016 See Documentation/power/swsusp-and-swap-files.txt
2017
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002018 retain_initrd [RAM] Keep initrd memory after extraction
2019
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020 rhash_entries= [KNL,NET]
2021 Set number of hash buckets for route cache
2022
2023 riscom8= [HW,SERIAL]
2024 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2025
2026 ro [KNL] Mount root device read-only on boot
2027
2028 root= [KNL] Root filesystem
2029
2030 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2031 mount the root filesystem
2032
2033 rootflags= [KNL] Set root filesystem mount option string
2034
2035 rootfstype= [KNL] Set root filesystem type
2036
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002037 rootwait [KNL] Wait (indefinitely) for root device to show up.
2038 Useful for devices that are detected asynchronously
2039 (e.g. USB and MMC devices).
2040
James Morris20510f22007-10-16 23:31:32 -07002041 root_plug.vendor_id=
2042 [ROOTPLUG] Override the default vendor ID
2043
2044 root_plug.product_id=
2045 [ROOTPLUG] Override the default product ID
2046
2047 root_plug.debug=
2048 [ROOTPLUG] Enable debugging output
2049
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050 rw [KNL] Mount root device read-write on boot
2051
2052 S [KNL] Run init in single mode
2053
2054 sa1100ir [NET]
2055 See drivers/net/irda/sa1100_ir.c.
2056
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002058
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2060 Format: <io>[,<timeout>[,<isapnp>]]
2061
2062 scsi_debug_*= [SCSI]
2063 See drivers/scsi/scsi_debug.c.
2064
2065 scsi_default_dev_flags=
2066 [SCSI] SCSI default device flags
2067 Format: <integer>
2068
2069 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2070 Format: <vendor>:<model>:<flags>
2071 (flags are integer value)
2072
Randy Dunlap6af66322007-11-14 16:52:25 -08002073 scsi_logging_level= [SCSI] a bit mask of logging levels
2074 See drivers/scsi/scsi_logging.h for bits. Also
2075 settable via sysctl at dev.scsi.logging_level
2076 (/proc/sys/dev/scsi/logging_level).
2077 There is also a nice 'scsi_logging_level' script in the
2078 S390-tools package, available for download at
2079 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002081 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2082 discovered. async scans them in kernel threads,
2083 allowing boot to proceed. none ignores them, expecting
2084 user space to do the scan.
2085
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002086 security= [SECURITY] Choose a security module to enable at boot.
2087 If this boot parameter is not specified, only the first
2088 security module asking for security registration will be
2089 loaded. An invalid security module name will be treated
2090 as if no module has been chosen.
2091
2092 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002093 Format: { "0" | "1" }
2094 See security/selinux/Kconfig help text.
2095 0 -- disable.
2096 1 -- enable.
2097 Default value is set via kernel config option.
2098 If enabled at boot time, /selinux/disable can be used
2099 later to disable prior to initial policy load.
2100
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002101 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103 shapers= [NET]
2104 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002105
Yinghai Lub05f78f2008-08-22 01:32:50 -07002106 show_msr= [x86] show boot-time MSR settings
2107 Format: { <integer> }
2108 Show boot-time (BIOS-initialized) MSR settings.
2109 The parameter means the number of CPUs to show,
2110 for example 1 means boot CPU only.
2111
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112 sim710= [SCSI,HW]
2113 See header of drivers/scsi/sim710.c.
2114
2115 simeth= [IA-64]
2116 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002117
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 slram= [HW,MTD]
2119
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002120 slub_debug[=options[,slabs]] [MM, SLUB]
2121 Enabling slub_debug allows one to determine the
2122 culprit if slab objects become corrupted. Enabling
2123 slub_debug can create guard zones around objects and
2124 may poison objects when not in use. Also tracks the
2125 last alloc / free. For more information see
2126 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002127
2128 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002129 Determines the maximum allowed order for slabs.
2130 A high setting may cause OOMs due to memory
2131 fragmentation. For more information see
2132 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002133
2134 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002135 The minimum number of objects per slab. SLUB will
2136 increase the slab order up to slub_max_order to
2137 generate a sufficiently large slab able to contain
2138 the number of objects indicated. The higher the number
2139 of objects the smaller the overhead of tracking slabs
2140 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002141 For more information see Documentation/vm/slub.txt.
2142
2143 slub_min_order= [MM, SLUB]
2144 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002145 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002146 For more information see Documentation/vm/slub.txt.
2147
2148 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002149 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002150 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002151 allocs to different slabs. Debug options disable
2152 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002153 For more information see Documentation/vm/slub.txt.
2154
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 smart2= [HW]
2156 Format: <io1>[,<io2>[,...,<io8>]]
2157
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002158 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002159 attempt to substitute SMP alternatives once at boot.
2160
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002161 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2162 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2163 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2164 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2165 smsc-ircc2.ircc_irq= [HW] IRQ line
2166 smsc-ircc2.ircc_dma= [HW] DMA channel
2167 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2168 0: Toshiba Satellite 1800 (GP data pin select)
2169 1: Fast pin select (default)
2170 2: ATC IRMode
2171
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 snd-ad1816a= [HW,ALSA]
2173
2174 snd-ad1848= [HW,ALSA]
2175
2176 snd-ali5451= [HW,ALSA]
2177
2178 snd-als100= [HW,ALSA]
2179
2180 snd-als4000= [HW,ALSA]
2181
2182 snd-azt2320= [HW,ALSA]
2183
2184 snd-cmi8330= [HW,ALSA]
2185
2186 snd-cmipci= [HW,ALSA]
2187
2188 snd-cs4231= [HW,ALSA]
2189
2190 snd-cs4232= [HW,ALSA]
2191
2192 snd-cs4236= [HW,ALSA]
2193
2194 snd-cs4281= [HW,ALSA]
2195
2196 snd-cs46xx= [HW,ALSA]
2197
2198 snd-dt019x= [HW,ALSA]
2199
2200 snd-dummy= [HW,ALSA]
2201
2202 snd-emu10k1= [HW,ALSA]
2203
2204 snd-ens1370= [HW,ALSA]
2205
2206 snd-ens1371= [HW,ALSA]
2207
2208 snd-es968= [HW,ALSA]
2209
2210 snd-es1688= [HW,ALSA]
2211
2212 snd-es18xx= [HW,ALSA]
2213
2214 snd-es1938= [HW,ALSA]
2215
2216 snd-es1968= [HW,ALSA]
2217
2218 snd-fm801= [HW,ALSA]
2219
2220 snd-gusclassic= [HW,ALSA]
2221
2222 snd-gusextreme= [HW,ALSA]
2223
2224 snd-gusmax= [HW,ALSA]
2225
2226 snd-hdsp= [HW,ALSA]
2227
2228 snd-ice1712= [HW,ALSA]
2229
2230 snd-intel8x0= [HW,ALSA]
2231
2232 snd-interwave= [HW,ALSA]
2233
2234 snd-interwave-stb=
2235 [HW,ALSA]
2236
2237 snd-korg1212= [HW,ALSA]
2238
2239 snd-maestro3= [HW,ALSA]
2240
2241 snd-mpu401= [HW,ALSA]
2242
2243 snd-mtpav= [HW,ALSA]
2244
2245 snd-nm256= [HW,ALSA]
2246
2247 snd-opl3sa2= [HW,ALSA]
2248
2249 snd-opti92x-ad1848=
2250 [HW,ALSA]
2251
2252 snd-opti92x-cs4231=
2253 [HW,ALSA]
2254
2255 snd-opti93x= [HW,ALSA]
2256
2257 snd-pmac= [HW,ALSA]
2258
2259 snd-rme32= [HW,ALSA]
2260
2261 snd-rme96= [HW,ALSA]
2262
2263 snd-rme9652= [HW,ALSA]
2264
2265 snd-sb8= [HW,ALSA]
2266
2267 snd-sb16= [HW,ALSA]
2268
2269 snd-sbawe= [HW,ALSA]
2270
2271 snd-serial= [HW,ALSA]
2272
2273 snd-sgalaxy= [HW,ALSA]
2274
2275 snd-sonicvibes= [HW,ALSA]
2276
2277 snd-sun-amd7930=
2278 [HW,ALSA]
2279
2280 snd-sun-cs4231= [HW,ALSA]
2281
2282 snd-trident= [HW,ALSA]
2283
2284 snd-usb-audio= [HW,ALSA,USB]
2285
2286 snd-via82xx= [HW,ALSA]
2287
2288 snd-virmidi= [HW,ALSA]
2289
2290 snd-wavefront= [HW,ALSA]
2291
2292 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002293
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002294 softlockup_panic=
2295 [KNL] Should the soft-lockup detector generate panics.
2296
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2298 See Documentation/sonypi.txt
2299
2300 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002301 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302
2303 spia_io_base= [HW,MTD]
2304 spia_fio_base=
2305 spia_pedr=
2306 spia_peddr=
2307
2308 sscape= [HW,OSS]
2309 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002310
Linus Torvalds1da177e2005-04-16 15:20:36 -07002311 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2312 See Documentation/scsi/st.txt.
2313
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002314 stacktrace [FTRACE]
2315 Enabled the stack tracer on boot up.
2316
Linus Torvalds1da177e2005-04-16 15:20:36 -07002317 sti= [PARISC,HW]
2318 Format: <num>
2319 Set the STI (builtin display/keyboard on the HP-PARISC
2320 machines) console (graphic card) which should be used
2321 as the initial boot-console.
2322 See also comment in drivers/video/console/sticore.c.
2323
2324 sti_font= [HW]
2325 See comment in drivers/video/console/sticore.c.
2326
2327 stifb= [HW]
2328 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2329
Greg Banks42a7fc42007-03-06 01:42:23 -08002330 sunrpc.pool_mode=
2331 [NFS]
2332 Control how the NFS server code allocates CPUs to
2333 service thread pools. Depending on how many NICs
2334 you have and where their interrupts are bound, this
2335 option will affect which CPUs will do NFS serving.
2336 Note: this parameter cannot be changed while the
2337 NFS server is running.
2338
2339 auto the server chooses an appropriate mode
2340 automatically using heuristics
2341 global a single global pool contains all CPUs
2342 percpu one pool for each CPU
2343 pernode one pool for each NUMA node (equivalent
2344 to global on non-NUMA machines)
2345
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002347
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 switches= [HW,M68k]
2349
2350 sym53c416= [HW,SCSI]
2351 See header of drivers/scsi/sym53c416.c.
2352
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002353 sysrq_always_enabled
2354 [KNL]
2355 Ignore sysrq setting - this boot parameter will
2356 neutralize any effect of /proc/sys/kernel/sysrq.
2357 Useful for debugging.
2358
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359 t128= [HW,SCSI]
2360 See header of drivers/scsi/t128.c.
2361
2362 tdfx= [HW,DRM]
2363
David Brownell77437fd2008-07-23 21:28:33 -07002364 test_suspend= [SUSPEND]
2365 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2366 standby suspend) as the system sleep state to briefly
2367 enter during system startup. The system is woken from
2368 this state using a wakeup-capable RTC alarm.
2369
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 thash_entries= [KNL,NET]
2371 Set number of hash buckets for TCP connection
2372
Len Brownf8707ec2007-08-12 00:12:54 -04002373 thermal.act= [HW,ACPI]
2374 -1: disable all active trip points in all thermal zones
2375 <degrees C>: override all lowest active trip points
2376
Len Brownc52a7412007-08-14 15:49:32 -04002377 thermal.crt= [HW,ACPI]
2378 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002379 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002380
Len Brownf5487142007-08-12 00:12:44 -04002381 thermal.nocrt= [HW,ACPI]
2382 Set to disable actions on ACPI thermal zone
2383 critical and hot trip points.
2384
Len Brown72b33ef2007-08-12 00:12:17 -04002385 thermal.off= [HW,ACPI]
2386 1: disable ACPI thermal control
2387
Len Browna70cdc52007-08-12 00:12:35 -04002388 thermal.psv= [HW,ACPI]
2389 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002390 <degrees C>: override all passive trip points to this
2391 value
Len Browna70cdc52007-08-12 00:12:35 -04002392
Len Brown730ff342007-08-12 00:12:26 -04002393 thermal.tzp= [HW,ACPI]
2394 Specify global default ACPI thermal zone polling rate
2395 <deci-seconds>: poll all this frequency
2396 0: no polling (default)
2397
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398 tmscsim= [HW,SCSI]
2399 See comment before function dc390_setup() in
2400 drivers/scsi/tmscsim.c.
2401
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002402 topology= [S390]
2403 Format: {off | on}
2404 Specify if the kernel should make use of the cpu
2405 topology informations if the hardware supports these.
2406 The scheduler will make use of these informations and
2407 e.g. base its process migration decisions on it.
2408 Default is off.
2409
Linus Torvalds1da177e2005-04-16 15:20:36 -07002410 tp720= [HW,PS2]
2411
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002412 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2413
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002415 Format:
2416 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2417
Alok Kataria395628e2008-10-24 17:22:01 -07002418 tsc= Disable clocksource-must-verify flag for TSC.
2419 Format: <string>
2420 [x86] reliable: mark tsc clocksource as reliable, this
2421 disables clocksource verification at runtime.
2422 Used to enable high-resolution timer mode on older
2423 hardware, and in virtualized environment.
2424
Randy Dunlapa9913042005-10-23 12:57:11 -07002425 turbografx.map[2|3]= [HW,JOY]
2426 TurboGraFX parallel port interface
2427 Format:
2428 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429 See also Documentation/input/joystick-parport.txt
2430
2431 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2432 See header of drivers/scsi/u14-34f.c.
2433
2434 uart401= [HW,OSS]
2435 Format: <io>,<irq>
2436
2437 uart6850= [HW,OSS]
2438 Format: <io>,<irq>
2439
Alan Stern5f8364b2006-12-05 16:29:55 -05002440 uhci-hcd.ignore_oc=
2441 [USB] Ignore overcurrent events (default N).
2442 Some badly-designed motherboards generate lots of
2443 bogus events, for ports that aren't wired to
2444 anything. Set this parameter to avoid log spamming.
2445 Note that genuine overcurrent events won't be
2446 reported either.
2447
Simon Arlotte3a61b02008-07-19 23:32:54 +01002448 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302449 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002450 Set unknown_nmi_panic=1 early on boot.
2451
Alan Sternb5e795f2007-02-20 15:00:53 -05002452 usbcore.autosuspend=
2453 [USB] The autosuspend time delay (in seconds) used
2454 for newly-detected USB devices (default 2). This
2455 is the time required before an idle device will be
2456 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002457 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002458
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002459 usbcore.usbfs_snoop=
2460 [USB] Set to log all usbfs traffic (default 0 = off).
2461
2462 usbcore.blinkenlights=
2463 [USB] Set to cycle leds on hubs (default 0 = off).
2464
2465 usbcore.old_scheme_first=
2466 [USB] Start with the old device initialization
2467 scheme (default 0 = off).
2468
2469 usbcore.use_both_schemes=
2470 [USB] Try the other device initialization scheme
2471 if the first one fails (default 1 = enabled).
2472
2473 usbcore.initial_descriptor_timeout=
2474 [USB] Specifies timeout for the initial 64-byte
2475 USB_REQ_GET_DESCRIPTOR request in milliseconds
2476 (default 5000 = 5.0 seconds).
2477
Linus Torvalds1da177e2005-04-16 15:20:36 -07002478 usbhid.mousepoll=
2479 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002480
Alan Sternd4f373e2008-11-10 14:07:45 -05002481 usb-storage.delay_use=
2482 [UMS] The delay in seconds before a new device is
2483 scanned for Logical Units (default 5).
2484
2485 usb-storage.quirks=
2486 [UMS] A list of quirks entries to supplement or
2487 override the built-in unusual_devs list. List
2488 entries are separated by commas. Each entry has
2489 the form VID:PID:Flags where VID and PID are Vendor
2490 and Product ID values (4-digit hex numbers) and
2491 Flags is a set of characters, each corresponding
2492 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002493 a = SANE_SENSE (collect more than 18 bytes
2494 of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002495 c = FIX_CAPACITY (decrease the reported
2496 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002497 h = CAPACITY_HEURISTICS (decrease the
2498 reported device capacity by one
2499 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002500 i = IGNORE_DEVICE (don't bind to this
2501 device);
2502 l = NOT_LOCKABLE (don't try to lock and
2503 unlock ejectable media);
2504 m = MAX_SECTORS_64 (don't transfer more
2505 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002506 o = CAPACITY_OK (accept the capacity
2507 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002508 r = IGNORE_RESIDUE (the device reports
2509 bogus residue values);
2510 s = SINGLE_LUN (the device has only one
2511 Logical Unit);
2512 w = NO_WP_DETECT (don't test whether the
2513 medium is write-protected).
2514 Example: quirks=0419:aaf5:rl,0421:0433:rc
2515
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302516 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002517 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002518 vdso=1: enable VDSO (default)
2519 vdso=0: disable VDSO mapping
2520
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302521 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002522 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2523 vdso32=1: enable 32-bit VDSO (default)
2524 vdso32=0: disable 32-bit VDSO mapping
2525
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002526 vector= [IA-64,SMP]
2527 vector=percpu: enable percpu vector domain
2528
Linus Torvalds1da177e2005-04-16 15:20:36 -07002529 video= [FB] Frame buffer configuration
2530 See Documentation/fb/modedb.txt.
2531
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002532 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002533 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002534 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535 Use vga=ask for menu.
2536 This is actually a boot loader parameter; the value is
2537 passed to the kernel using a special protocol.
2538
Randy Dunlapa9913042005-10-23 12:57:11 -07002539 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002540 size of <nn>. This can be used to increase the
2541 minimum size (128MB on x86). It can also be used to
2542 decrease the size and leave more room for directly
2543 mapped kernel RAM.
2544
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002545 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2546 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002547
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002548 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2549 Format: <command>
2550
2551 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2552 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002553
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002554 vt.default_blu= [VT]
2555 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2556 Change the default blue palette of the console.
2557 This is a 16-member array composed of values
2558 ranging from 0-255.
2559
2560 vt.default_grn= [VT]
2561 Format: <green0>,<green1>,<green2>,...,<green15>
2562 Change the default green palette of the console.
2563 This is a 16-member array composed of values
2564 ranging from 0-255.
2565
2566 vt.default_red= [VT]
2567 Format: <red0>,<red1>,<red2>,...,<red15>
2568 Change the default red palette of the console.
2569 This is a 16-member array composed of values
2570 ranging from 0-255.
2571
2572 vt.default_utf8=
2573 [VT]
2574 Format=<0|1>
2575 Set system-wide default UTF-8 mode for all tty's.
2576 Default is 1, i.e. UTF-8 mode is enabled for all
2577 newly opened terminals.
2578
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579 waveartist= [HW,OSS]
2580 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002581
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 wd33c93= [HW,SCSI]
2583 See header of drivers/scsi/wd33c93.c.
2584
2585 wd7000= [HW,SCSI]
2586 See header of drivers/scsi/wd7000.c.
2587
2588 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002589 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002591 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2592 default x2apic cluster mode on platforms
2593 supporting x2apic.
2594
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2596 xd_geo= See header of drivers/block/xd.c.
2597
2598 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002599 Format:
2600 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002601
Randy Dunlapa9913042005-10-23 12:57:11 -07002602______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002603
2604TODO:
2605
2606 Add documentation for ALSA options.
2607 Add more DRM drivers.