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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 ISAPNP ISA PnP code is enabled.
58 ISDN Appropriate ISDN support is enabled.
59 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070060 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 LP Printer support is enabled.
62 LOOP Loopback device support is enabled.
63 M68k M68k architecture is enabled.
64 These options have more detailed description inside of
65 Documentation/m68k/kernel-options.txt.
66 MCA MCA bus support is enabled.
67 MDA MDA console support is enabled.
68 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070069 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070070 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 NET Appropriate network support is enabled.
72 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070073 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 NFS Appropriate NFS support is enabled.
75 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070076 PV_OPS A paravirtualized kernel is enabled.
77 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 PARISC The PA-RISC architecture is enabled.
79 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070080 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 PCMCIA The PCMCIA subsystem is enabled.
82 PNP Plug & Play support is enabled.
83 PPC PowerPC architecture is enabled.
84 PPT Parallel port support is enabled.
85 PS2 Appropriate PS/2 support is enabled.
86 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070087 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 S390 S390 architecture is enabled.
89 SCSI Appropriate SCSI support is enabled.
90 A lot of drivers has their options described inside of
91 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070092 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 SELINUX SELinux support is enabled.
94 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090095 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 SMP The kernel is an SMP kernel.
97 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070098 SWSUSP Software suspend (hibernation) is enabled.
99 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500100 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500102 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 USB USB support is enabled.
104 USBHID USB Human Interface Device support is enabled.
105 V4L Video For Linux support is enabled.
106 VGA The VGA console has been enabled.
107 VT Virtual terminal support is enabled.
108 WDT Watchdog support is enabled.
109 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700110 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 X86-64 X86-64 architecture is enabled.
112 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700113 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200114 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116In addition, the following text indicates that the option:
117
118 BUGS= Relates to possible processor bugs on the said processor.
119 KNL Is a kernel start-up parameter.
120 BOOT Is a boot loader parameter.
121
122Parameters denoted with BOOT are actually interpreted by the boot
123loader, and have no meaning to the kernel directly.
124Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500125need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
Karsten Weiss55588702007-02-13 13:26:21 +0100127There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700128See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100129
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
131a trailing = on the name of any parameter states that that parameter will
132be entered as an environment variable, whereas its absence indicates that
133it will appear as a kernel argument readable via /proc/cmdline by programs
134running once the system is up.
135
jens m. noedler9c4751f2006-09-29 02:00:27 -0700136The number of kernel parameters is not limited, but the length of the
137complete command line (parameters including spaces etc.) is limited to
138a fixed number of characters. This limit depends on the architecture
139and is between 256 and 4096 characters. It is defined in the file
140./include/asm/setup.h as COMMAND_LINE_SIZE.
141
142
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530143 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800144 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800145 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 force -- enable ACPI if default was off
147 off -- disable ACPI if default was on
148 noirq -- do not use ACPI for IRQ routing
149 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700150 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800152 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
Randy Dunlap53471122008-03-12 18:10:51 -0400154 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
Len Browna1fdcc02007-03-11 03:26:14 -0400156 acpi_apic_instance= [ACPI, IOAPIC]
157 Format: <int>
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400160 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400161
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
164 acpi_backlight=video
165 If set to vendor, prefer vendor specific driver
166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
167 of the ACPI video.ko driver.
168
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
173 debug output. Bits in debug_layer correspond to a
174 _COMPONENT in an ACPI source file, e.g.,
175 #define _COMPONENT ACPI_PCI_COMPONENT
176 Bits in debug_level correspond to a level in
177 ACPI_DEBUG_PRINT statements, e.g.,
178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600179 The debug_level mask defaults to "info". See
180 Documentation/acpi/debug.txt for more information about
181 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600183 Enable processor driver info messages:
184 acpi.debug_layer=0x20000000
185 Enable PCI/PCI interrupt routing info messages:
186 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700187 Enable AML "Debug" output, i.e., stores to the Debug
188 object while interpreting AML:
189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700190 Enable all messages related to ACPI hardware:
191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200192
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700193 Some values produce so much output that the system is
194 unusable. The "log_buf_len" parameter may be useful
195 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800196
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700197 acpi_display_output= [HW,ACPI]
198 acpi_display_output=vendor
199 acpi_display_output=video
200 See above.
201
202 acpi_irq_balance [HW,ACPI]
203 ACPI will balance active IRQs
204 default in APIC mode
205
206 acpi_irq_nobalance [HW,ACPI]
207 ACPI will not move active IRQs (default)
208 default in PIC mode
209
210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
211 Format: <irq>,<irq>...
212
213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 use by PCI
215 Format: <irq>,<irq>...
216
217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
218
219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
220 Format: To spoof as Windows 98: ="Microsoft Windows"
221
222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
223 acpi_osi="string1" # add string1 -- only one string
224 acpi_osi="!string2" # remove built-in string2
225 acpi_osi= # disable all strings
226
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530227 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
231
Randy Dunlap4af94f32009-04-17 18:30:28 -0700232 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
233 Format: { level | edge | high | low }
234
235 acpi_serialize [HW,ACPI] force serialization of AML methods
236
237 acpi_skip_timer_override [HW,ACPI]
238 Recognize and ignore IRQ0/pin2 Interrupt Override.
239 For broken nForce2 BIOS resulting in XT-PIC timer.
240
241 acpi_sleep= [HW,ACPI] Sleep options
242 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
243 old_ordering, s4_nonvs }
244 See Documentation/power/video.txt for information on
245 s3_bios and s3_mode.
246 s3_beep is for debugging; it makes the PC's speaker beep
247 as soon as the kernel's real-mode entry point is called.
248 s4_nohwsig prevents ACPI hardware signature from being
249 used during resume from hibernation.
250 old_ordering causes the ACPI 1.0 ordering of the _PTS
251 control method, with respect to putting devices into
252 low power states, to be enforced (the ACPI 2.0 ordering
253 of _PTS is used by default).
254 s4_nonvs prevents the kernel from saving/restoring the
255 ACPI NVS memory during hibernation.
256
257 acpi_use_timer_override [HW,ACPI]
258 Use timer override. For some broken Nvidia NF5 boards
259 that require a timer override, but don't have HPET
260
Luca Tettamanti7e905602009-03-30 00:01:27 +0200261 acpi_enforce_resources= [ACPI]
262 { strict | lax | no }
263 Check for resource conflicts between native drivers
264 and ACPI OperationRegions (SystemIO and SystemMemory
265 only). IO ports and memory declared in ACPI might be
266 used by the ACPI subsystem in arbitrary AML code and
267 can interfere with legacy drivers.
268 strict (default): access to resources claimed by ACPI
269 is denied; legacy drivers trying to access reserved
270 resources will fail to bind to device using them.
271 lax: access to resources claimed by ACPI is allowed;
272 legacy drivers trying to access reserved resources
273 will bind successfully but a warning message is logged.
274 no: ACPI OperationRegions are not marked as reserved,
275 no further checks are performed.
276
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 ad1848= [HW,OSS]
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
279
Randy Dunlap4af94f32009-04-17 18:30:28 -0700280 add_efi_memmap [EFI; X86] Include EFI memory map in
281 kernel's map of available physical RAM.
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 advansys= [HW,SCSI]
284 See header of drivers/scsi/advansys.c.
285
286 advwdt= [HW,WDT] Advantech WDT
287 Format: <iostart>,<iostop>
288
289 aedsp16= [HW,OSS] Audio Excel DSP 16
290 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
291 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700292
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700293 agp= [AGP]
294 { off | try_unsupported }
295 off: disable AGP support
296 try_unsupported: try to drive unsupported chipsets
297 (may crash computer or cause data corruption)
298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 aha152x= [HW,SCSI]
300 See Documentation/scsi/aha152x.txt.
301
302 aha1542= [HW,SCSI]
303 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
304
305 aic7xxx= [HW,SCSI]
306 See Documentation/scsi/aic7xxx.txt.
307
308 aic79xx= [HW,SCSI]
309 See Documentation/scsi/aic79xx.txt.
310
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200311 amd_iommu= [HW,X86-84]
312 Pass parameters to the AMD IOMMU driver in the system.
313 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200314 isolate - enable device isolation (each device, as far
315 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100316 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100317 share - put every device behind one IOMMU into the
318 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900319 fullflush - enable flushing of IO/TLB entries when
320 they are unmapped. Otherwise they are
321 flushed before they will be reused, which
322 is a lot of faster
323
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 amijoy.map= [HW,JOY] Amiga joystick support
325 Map of devices attached to JOY0DAT and JOY1DAT
326 Format: <a>,<b>
327 See also Documentation/kernel/input/joystick.txt
328
329 analog.map= [HW,JOY] Analog joystick and gamepad support
330 Specifies type or capabilities of an analog joystick
331 connected to one of 16 gameports
332 Format: <type1>,<type2>,..<type16>
333
Randy Dunlapa9913042005-10-23 12:57:11 -0700334 apc= [HW,SPARC]
335 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 Format: noidle
337 Disable APC CPU standby support. SPARCstation-Fox does
338 not play well with APC CPU idle - disable it if you have
339 APC and your system crashes randomly.
340
Randy Dunlapca1eda22009-05-06 16:02:58 -0700341 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700342 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 Format: { quiet (default) | verbose | debug }
344 Change the amount of debugging information output
345 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700346
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700348 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
351 Format: <io>,<irq>,<nodeID>
352
353 ataflop= [HW,M68k]
354
355 atarimouse= [HW,MOUSE] Atari Mouse
356
357 atascsi= [HW,SCSI] Atari SCSI
358
359 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
360 EzKey and similar keyboards
361
362 atkbd.reset= [HW] Reset keyboard during initialization
363
Randy Dunlapa9913042005-10-23 12:57:11 -0700364 atkbd.set= [HW] Select keyboard code set
365 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366
367 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
368 keyboards
369
370 atkbd.softraw= [HW] Choose between synthetic and real raw mode
371 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700372
373 atkbd.softrepeat= [HW]
374 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375
376 autotest [IA64]
377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 baycom_epp= [HW,AX25]
379 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700380
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
382 Format: <io>,<mode>
383 See header of drivers/net/hamradio/baycom_par.c.
384
Randy Dunlapa9913042005-10-23 12:57:11 -0700385 baycom_ser_fdx= [HW,AX25]
386 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 Format: <io>,<irq>,<mode>[,<baud>]
388 See header of drivers/net/hamradio/baycom_ser_fdx.c.
389
Randy Dunlapa9913042005-10-23 12:57:11 -0700390 baycom_ser_hdx= [HW,AX25]
391 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 Format: <io>,<irq>,<mode>
393 See header of drivers/net/hamradio/baycom_ser_hdx.c.
394
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700395 boot_delay= Milliseconds to delay each printk during boot.
396 Values larger than 10 seconds (10000) are changed to
397 no delay (0).
398 Format: integer
399
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700400 bootmem_debug [KNL] Enable bootmem allocator debug messages.
401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700403 bttv.radio= Most important insmod options are available as
404 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
406 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
407
408 BusLogic= [HW,SCSI]
409 See drivers/scsi/BusLogic.c, comment before function
410 BusLogic_ParseDriverOptions().
411
412 c101= [NET] Moxa C101 synchronous serial card
413
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700414 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 Sometimes CPU hardware bugs make them report the cache
416 size incorrectly. The kernel will attempt work arounds
417 to fix known problems, but for some CPUs it is not
418 possible to determine what the correct size should be.
419 This option provides an override for these situations.
420
James Morris20510f22007-10-16 23:31:32 -0700421 capability.disable=
422 [SECURITY] Disable capabilities. This would normally
423 be used only if an alternative security model is to be
424 configured. Potentially dangerous and should only be
425 used if you are entirely sure of the consequences.
426
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100427 ccw_timeout_log [S390]
428 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429
Paul Menage8bab8dd2008-04-04 14:29:57 -0700430 cgroup_disable= [KNL] Disable a particular controller
431 Format: {name of the controller(s) to disable}
432 {Currently supported controllers - "memory"}
433
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 checkreqprot [SELINUX] Set initial checkreqprot flag value.
435 Format: { "0" | "1" }
436 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700437 0 -- check protection applied by kernel (includes
438 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 1 -- check protection requested by application.
440 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700441 Value can be changed at runtime via
442 /selinux/checkreqprot.
443
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100444 cio_ignore= [S390]
445 See Documentation/s390/CommonIO for details.
446
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700447 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700448 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200449 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700450 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200451 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 Format: { pit | tsc | cyclone | pmtmr }
453
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700454 clocksource= [GENERIC_TIME] Override the default clocksource
455 Format: <string>
456 Override the default clocksource and use the clocksource
457 with the name specified.
458 Some clocksource names to choose from, depending on
459 the platform:
460 [all] jiffies (this is the base, fallback clocksource)
461 [ACPI] acpi_pm
462 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
463 pxa_timer,timer3,32k_counter,timer0_1
464 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700465 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700466 scx200_hrt on Geode; cyclone on IBM x440
467 [MIPS] MIPS
468 [PARISC] cr16
469 [S390] tod
470 [SH] SuperH
471 [SPARC64] tick
472 [X86-64] hpet,tsc
473
Andi Kleenac72e782008-01-30 13:33:21 +0100474 clearcpuid=BITNUM [X86]
475 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800476 arch/x86/include/asm/cpufeature.h for the valid bit
477 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100478 stable over kernel options, but the vendor specific
479 ones should be.
480 Also note that user programs calling CPUID directly
481 or using the feature without checking anything
482 will still see it. This just prevents it from
483 being used by the kernel or shown in /proc/cpuinfo.
484 Also note the kernel might malfunction if you disable
485 some critical bits.
486
Robert Jennings14f966e2009-04-15 05:55:32 +0000487 cmo_free_hint= [PPC] Format: { yes | no }
488 Specify whether pages are marked as being inactive
489 when they are freed. This is used in CMO environments
490 to determine OS memory pressure for page stealing by
491 a hypervisor.
492 Default: yes
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
Daniel Mackf324edc2009-06-16 15:33:52 -0700542 consoleblank= [KNL] The console blank (screen saver) timeout in
543 seconds. Defaults to 10*60 = 10mins. A value of 0
544 disables the blank timer.
545
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800546 coredump_filter=
547 [KNL] Change the default value for
548 /proc/<pid>/coredump_filter.
549 See also Documentation/filesystems/proc.txt.
550
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700552 Format:
553 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700555 crashkernel=nn[KMG]@ss[KMG]
556 [KNL] Reserve a chunk of physical memory to
557 hold a kernel to switch to with kexec on panic.
558
Bernhard Wallefb391592007-10-18 23:41:02 -0700559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for a example.
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 cs89x0_dma= [HW,NET]
567 Format: <dma>
568
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700571
Randy Dunlapa9913042005-10-23 12:57:11 -0700572 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 See header of drivers/s390/block/dasd_devmap.c.
574
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
579
580 debug [KNL] Enable kernel debugging (events log level).
581
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700582 debug_locks_verbose=
583 [KNL] verbose self-tests
584 Format=<0|1>
585 Print debugging info while doing the locking API
586 self-tests.
587 We default to 0 (no extra messages), setting it to
588 1 will print _a lot_ more information - normally
589 only useful to kernel developers.
590
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700591 debug_objects [KNL] Enable object debugging
592
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500593 no_debug_objects
594 [KNL] Disable object debugging
595
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200596 debugpat [X86] Enable PAT debugging
597
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200598 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 Format: <area>[,<node>]
600 See also Documentation/networking/decnet.txt.
601
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700602 default_hugepagesz=
603 [same as hugepagesz=] The size of the default
604 HugeTLB page size. This is the size represented by
605 the legacy /proc/ hugepages APIs, used for SHM, and
606 default size when mounting hugetlbfs filesystems.
607 Defaults to the default architecture's huge page size
608 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700609
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 dhash_entries= [KNL]
611 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700612
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 digi= [HW,SERIAL]
614 IO parameters + enable/disable command.
615
616 digiepca= [HW,SERIAL]
617 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000618 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619
Yinghai Lu95ffa242008-04-29 03:52:33 -0700620 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700621 The kernel tries to adjust MTRR layout from continuous
622 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700623 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700624
Yinghai Lu093af8d2008-01-30 13:33:32 +0100625 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100626 By default the kernel will trim any uncacheable
627 memory out of your available memory pool based on
628 MTRR settings. This parameter disables that behavior,
629 possibly causing your machine to run very slowly.
630
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530631 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700632 Disable PIN 1 of APIC timer
633 Can be useful to work around chipset bugs.
634
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 dmasound= [HW,OSS] Sound subsystem buffers
636
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700637 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
638 this option disables the debugging code at boot.
639
640 dma_debug_entries=<number>
641 This option allows to tune the number of preallocated
642 entries for DMA-API debugging code. One entry is
643 required per DMA-API allocation. Use this if the
644 DMA-API debugging code disables itself because the
645 architectural default is too low.
646
Joerg Roedel1745de52009-05-22 21:49:51 +0200647 dma_debug_driver=<driver_name>
648 With this option the DMA-API debugging driver
649 filter feature can be enabled at boot time. Just
650 pass the driver to filter for as the parameter.
651 The filter can be disabled or changed to another
652 driver later using sysfs.
653
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 dscc4.setup= [NET]
655
656 dtc3181e= [HW,SCSI]
657
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700658 dynamic_printk Enables pr_debug()/dev_dbg() calls if
659 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
660 These can also be switched on/off via
661 <debugfs>/dynamic_printk/modules
662
663 earlycon= [KNL] Output early console device and options.
664 uart[8250],io,<addr>[,options]
665 uart[8250],mmio,<addr>[,options]
666 Start an early, polled-mode console on the 8250/16550
667 UART at the specified I/O port or MMIO address.
668 The options are the same as for ttyS, above.
669
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530670 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 earlyprintk=vga
672 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700673 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674
Randy Dunlapa9913042005-10-23 12:57:11 -0700675 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 takes over.
677
Yinghai Lu5c059172008-07-24 17:29:40 -0700678 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679
680 Currently only ttyS0 and ttyS1 are supported.
681
682 Interaction with the standard serial driver is not
683 very good.
684
685 The VGA output is eventually overwritten by the real
686 console.
687
688 eata= [HW,SCSI]
689
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700691 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 eisa_irq_edge= [PARISC,HW]
694 See header of drivers/parisc/eisa.c.
695
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700696 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700698 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699
700 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800701 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700702 See Documentation/block/as-iosched.txt and
703 Documentation/block/deadline-iosched.txt for details.
704
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530705 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700706 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800707 image elf header. Generally kexec loader will
708 pass this option to capture kernel.
709 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700711 enable_mtrr_cleanup [X86]
712 The kernel tries to adjust MTRR layout from continuous
713 to discrete, to make X server driver able to add WB
714 entry later. This parameter enables that.
715
Randy Dunlapca1eda22009-05-06 16:02:58 -0700716 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700717 Enable PIN 1 of APIC timer
718 Can be useful to work around chipset bugs
719 (in particular on some ATI chipsets).
720 The kernel tries to set a reasonable default.
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 enforcing [SELINUX] Set initial enforcing status.
723 Format: {"0" | "1"}
724 See security/selinux/Kconfig help text.
725 0 -- permissive (log only, no denials).
726 1 -- enforcing (deny and log).
727 Default value is 0.
728 Value can be changed at runtime via /selinux/enforce.
729
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 ether= [HW,NET] Ethernet cards parameters
731 This option is obsoleted by the "netdev=" option, which
732 has equivalent usage. See its documentation for details.
733
734 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
735 Format: <io>[,<irq>]
736
Akinobu Mitade1ba092006-12-08 02:39:42 -0800737 failslab=
738 fail_page_alloc=
739 fail_make_request=[KNL]
740 General fault injection mechanism.
741 Format: <interval>,<probability>,<space>,<times>
742 See also /Documentation/fault-injection/.
743
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 fd_mcs= [HW,SCSI]
745 See header of drivers/scsi/fd_mcs.c.
746
747 fdomain= [HW,SCSI]
748 See header of drivers/scsi/fdomain.c.
749
750 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000751 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
Alex Chiangf13ae302008-05-08 14:03:23 -0600753 force_pal_cache_flush
754 [IA-64] Avoid check_sal_cache_flush which may hang on
755 buggy SAL_CACHE_FLUSH implementations. Using this
756 parameter will force ia64_sal_cache_flush to call
757 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
758
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100759 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400760 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100761 as early as possible in order to facilitate early
762 boot debugging.
763
764 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400765 [FTRACE] will dump the trace buffers on oops.
766
767 ftrace_filter=[function-list]
768 [FTRACE] Limit the functions traced by the function
769 tracer at boot up. function-list is a comma separated
770 list of functions. This list can be changed at run
771 time by the set_ftrace_filter file in the debugfs
772 tracing directory.
773
774 ftrace_notrace=[function-list]
775 [FTRACE] Do not trace the functions specified in
776 function-list. This list can be changed at run time
777 by the set_ftrace_notrace file in the debugfs
778 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 gamecon.map[2|3]=
781 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
782 support via parallel port (up to 5 devices per port)
783 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
784 See also Documentation/input/joystick-parport.txt
785
786 gamma= [HW,DRM]
787
Yinghai Luaaf23042008-01-30 13:33:09 +0100788 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 Format: off | on
790 default: on
791
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700792 gcov_persist= [GCOV] When non-zero (default), profiling data for
793 kernel modules is saved and remains accessible via
794 debugfs, even when the module is unloaded/reloaded.
795 When zero, profiling data is discarded and associated
796 debugfs files are removed at module unload time.
797
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 gdth= [HW,SCSI]
799 See header of drivers/scsi/gdth.c.
800
801 gpt [EFI] Forces disk with valid GPT signature but
802 invalid Protective MBR to be treated as GPT.
803
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 gvp11= [HW,SCSI]
805
806 hashdist= [KNL,NUMA] Large hashes allocated during boot
807 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700808 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700809 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810
811 hcl= [IA-64] SGI's Hardware Graph compatibility layer
812
813 hd= [EIDE] (E)IDE hard drive subsystem geometry
814 Format: <cyl>,<head>,<sect>
815
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
817 size of <nn>. This works even on boxes that have no
818 highmem otherwise. This also works to reduce highmem
819 size on bigger boxes.
820
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800821 highres= [KNL] Enable/disable high resolution timer mode.
822 Valid parameters: "on", "off"
823 Default: "on"
824
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 hisax= [HW,ISDN]
826 See Documentation/isdn/README.HiSax.
827
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700828 hlt [BUGS=ARM,SH]
829
830 hpet= [X86-32,HPET] option to control HPET usage
831 Format: { enable (default) | disable | force |
832 verbose }
833 disable: disable HPET and use PIT instead
834 force: allow force enabled of undocumented chips (ICH4,
835 VIA, nVidia)
836 verbose: show contents of HPET registers during setup
837
Andi Kleenb4718e62008-07-23 21:27:51 -0700838 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
839 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700840 On x86-64 and powerpc, this option can be specified
841 multiple times interleaved with hugepages= to reserve
842 huge pages of different sizes. Valid pages sizes on
843 x86-64 are 2M (when the CPU supports "pse") and 1G
844 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700845 Note that 1GB pages can only be allocated at boot time
846 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900847
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100848 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
849 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100850 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
851 If specified, z/VM IUCV HVC accepts connections
852 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100853
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700854 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700855 or register an additional I2C bus that is not
856 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700857 Format:
858 <bus_id>,<clkrate>
859
Jiri Kosina36d95732008-10-06 02:51:09 -0400860 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200862 i8042.dumbkbd [HW] Pretend that controller can only read data from
863 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 (Don't attempt to blink the leds)
865 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500866 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400867 i8042.noloop [HW] Disable the AUX Loopback command while probing
868 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 i8042.nomux [HW] Don't check presence of an active multiplexing
870 controller
871 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
872 controllers
873 i8042.panicblink=
874 [HW] Frequency with which keyboard LEDs should blink
875 when kernel panics (default is 0.5 sec)
876 i8042.reset [HW] Reset the controller during init and cleanup
877 i8042.unlock [HW] Unlock (ignore) the keylock
878
879 i810= [HW,DRM]
880
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700881 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
882 indicates that the driver is running on unsupported
883 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
885 does not match list of supported models.
886 i8k.power_status
887 [HW] Report power status in /proc/i8k
888 (disabled by default)
889 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
890 capability is set.
891
892 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
893 See Documentation/mca.txt.
894
895 icn= [HW,ISDN]
896 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
897
David Fries0af80c02009-02-25 20:28:21 +0100898 ide-core.nodma= [HW] (E)IDE subsystem
899 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200900 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
901 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100902 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700904 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
905 Claim all unknown PCI IDE storage controllers.
906
Andi Kleenf039b752007-05-02 19:27:12 +0200907 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800908 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
909 Poll forces a polling idle loop that can slightly
910 improve the performance of waking up a idle CPU, but
911 will use a lot of power and make the system run hot.
912 Not recommended.
913 idle=mwait: On systems which support MONITOR/MWAIT but
914 the kernel chose to not use it because it doesn't save
915 as much power as a normal idle loop, use the
916 MONITOR/MWAIT idle loop anyways. Performance should be
917 the same as idle=poll.
918 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800919 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800920 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700921
Ingo Molnar792908222006-12-06 20:40:51 -0800922 ignore_loglevel [KNL]
923 Ignore loglevel setting - this will print /all/
924 kernel messages to the console. Useful for debugging.
925
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 ihash_entries= [KNL]
927 Set number of hash buckets for inode cache.
928
Mimi Zohar3323eec2009-02-04 09:06:58 -0500929 ima_audit= [IMA]
930 Format: { "0" | "1" }
931 0 -- integrity auditing messages. (Default)
932 1 -- enable informational integrity auditing messages.
933
934 ima_hash= [IMA]
935 Formt: { "sha1" | "md5" }
936 default: "sha1"
937
Eric Paris5789ba32009-05-21 15:47:06 -0400938 ima_tcb [IMA]
939 Load a policy which meets the needs of the Trusted
940 Computing Base. This means IMA will measure all
941 programs exec'd, files mmap'd for exec, and all files
942 opened for read by uid=0.
943
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 in2000= [HW,SCSI]
945 See header of drivers/scsi/in2000.c.
946
947 init= [KNL]
948 Format: <full_path>
949 Run specified binary instead of /sbin/init as init
950 process.
951
952 initcall_debug [KNL] Trace initcalls as they are executed. Useful
953 for working out where the kernel is dying during
954 startup.
955
956 initrd= [BOOT] Specify the location of the initial ramdisk
957
958 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
959 Format: <irq>
960
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700961 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800962 on
963 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700964 off
965 Disable intel iommu driver.
966 igfx_off [Default Off]
967 By default, gfx is mapped as normal device. If a gfx
968 device has a dedicated DMAR unit, the DMAR unit is
969 bypassed by not enabling DMAR with this option. In
970 this case, gfx device will use physical address for
971 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700972 forcedac [x86_64]
973 With this option iommu will not optimize to look
974 for io virtual address below 32 bit forcing dual
975 address cycle on pci bus for cards supporting greater
976 than 32 bit addressing. The default is to look
977 for translation below 32 bit and if not available
978 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800979 strict [Default Off]
980 With this option on every unmap_single operation will
981 result in a hardware IOTLB flush operation as opposed
982 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700983
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700984 inttest= [IA64]
985
986 iomem= Disable strict checking of access to MMIO memory
987 strict regions from userspace.
988 relaxed
989
990 iommu= [x86]
991 off
992 force
993 noforce
994 biomerge
995 panic
996 nopanic
997 merge
998 nomerge
999 forcesac
1000 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001001 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001002
1003 io7= [HW] IO7 for Marvel based alpha systems
1004 See comment before marvel_specify_io7 in
1005 arch/alpha/kernel/core_marvel.c.
1006
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301007 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001008 0x80
1009 Standard port 0x80 based delay
1010 0xed
1011 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001012 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001013 Simple two microseconds delay
1014 none
1015 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001016
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001018 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019
1020 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001021 See comment before ip2_setup() in
1022 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023
1024 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1025 See header of drivers/scsi/ips.c.
1026
Alan Cox200803d2005-06-28 20:45:18 -07001027 irqfixup [HW]
1028 When an interrupt is not handled search all handlers
1029 for it. Intended to get systems with badly broken
1030 firmware running.
1031
1032 irqpoll [HW]
1033 When an interrupt is not handled search all handlers
1034 for it. Also check all handlers each timer
1035 interrupt. Intended to get systems with badly broken
1036 firmware running.
1037
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001039 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040
1041 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001042 Format:
1043 <cpu number>,...,<cpu number>
1044 or
Li Zefanb225d442008-11-06 12:53:39 -08001045 <cpu number>-<cpu number>
1046 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001047 or a mixture
1048 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001049
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 This option can be used to specify one or more CPUs
1051 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001052 algorithms. You can move a process onto or off an
1053 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 <cpu number> begins at 0 and the maximum value is
1055 "number of CPUs in system - 1".
1056
1057 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001058 alternative -- manually setting the CPU mask of all
1059 tasks in the system -- can cause problems and
1060 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061
Randy Dunlapa9913042005-10-23 12:57:11 -07001062 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063
1064 js= [HW,JOY] Analog joystick
1065 See Documentation/input/joystick.txt.
1066
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001067 keepinitrd [HW,ARM]
1068
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301069 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001070 specifies the amount of memory usable by the kernel
1071 for non-movable allocations. The requested amount is
1072 spread evenly throughout all nodes in the system. The
1073 remaining memory in each node is used for Movable
1074 pages. In the event, a node is too small to have both
1075 kernelcore and Movable pages, kernelcore pages will
1076 take priority and other nodes will have a larger number
1077 of kernelcore pages. The Movable zone is used for the
1078 allocation of pages that may be reclaimed or moved
1079 by the page migration subsystem. This means that
1080 HugeTLB pages may not be allocated from this zone.
1081 Note that allocations like PTEs-from-HighMem still
1082 use the HighMem zone if it exists, and the Normal
1083 zone if it does not.
1084
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001085 kgdboc= [HW] kgdb over consoles.
1086 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001087 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001088 Format: <serial_device>[,baud]
1089
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001090 kmac= [MIPS] korina ethernet MAC address.
1091 Configure the RouterBoard 532 series on-chip
1092 Ethernet adapter MAC address.
1093
Catalin Marinas04f70332009-06-11 13:22:39 +01001094 kmemleak= [KNL] Boot-time kmemleak enable/disable
1095 Valid arguments: on, off
1096 Default: on
1097
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301098 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001099 in oops dumps.
1100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 l2cr= [PPC]
1102
Robert Brosea78bfbf2008-03-29 07:20:23 +11001103 l3cr= [PPC]
1104
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001105 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001106 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301108 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001109 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001110
FD Camifcb71f62008-01-06 19:08:56 +01001111 libata.dma= [LIBATA] DMA control
1112 libata.dma=0 Disable all PATA and SATA DMA
1113 libata.dma=1 PATA and SATA Disk DMA only
1114 libata.dma=2 ATAPI (CDROM) DMA only
1115 libata.dma=4 Compact Flash DMA only
1116 Combinations also work, so libata.dma=3 enables DMA
1117 for disks and CDROMs, but not CFs.
1118
Dave Jones78e70c22007-09-27 11:50:13 -04001119 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1120 when set.
1121 Format: <int>
1122
Tejun Heo33267322008-02-13 09:15:09 +09001123 libata.force= [LIBATA] Force configurations. The format is comma
1124 separated list of "[ID:]VAL" where ID is
1125 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1126 matching port, link or device. Basically, it matches
1127 the ATA ID string printed on console by libata. If
1128 the whole ID part is omitted, the last PORT and DEVICE
1129 values are used. If ID hasn't been specified yet, the
1130 configuration applies to all ports, links and devices.
1131
1132 If only DEVICE is omitted, the parameter applies to
1133 the port and all links and devices behind it. DEVICE
1134 number of 0 either selects the first device or the
1135 first fan-out link behind PMP device. It does not
1136 select the host link. DEVICE number of 15 selects the
1137 host link and device attached to it.
1138
1139 The VAL specifies the configuration to force. As long
1140 as there's no ambiguity shortcut notation is allowed.
1141 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1142 The following configurations can be forced.
1143
1144 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1145 Any ID with matching PORT is used.
1146
1147 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1148
1149 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1150 udma[/][16,25,33,44,66,100,133] notation is also
1151 allowed.
1152
1153 * [no]ncq: Turn on or off NCQ.
1154
Tejun Heo05944bd2008-08-13 20:19:09 +09001155 * nohrst, nosrst, norst: suppress hard, soft
1156 and both resets.
1157
Tejun Heo33267322008-02-13 09:15:09 +09001158 If there are multiple matching configurations changing
1159 the same attribute, the last one is used.
1160
Randy Dunlap7c4be252009-01-06 14:42:44 -08001161 lmb=debug [KNL] Enable lmb debug messages.
1162
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001164 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001166 lockd.nlm_grace_period=P [NFS] Assign grace period.
1167 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001169 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1170 Format: <integer>
1171
1172 lockd.nlm_timeout=T [NFS] Assign timeout value.
1173 Format: <integer>
1174
1175 lockd.nlm_udpport=M [NFS] Assign UDP port.
1176 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177
1178 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1179 Format: <irq>
1180
1181 loglevel= All Kernel Messages with a loglevel smaller than the
1182 console loglevel will be printed to the console. It can
1183 also be changed with klogd or other programs. The
1184 loglevels are defined as follows:
1185
1186 0 (KERN_EMERG) system is unusable
1187 1 (KERN_ALERT) action must be taken immediately
1188 2 (KERN_CRIT) critical conditions
1189 3 (KERN_ERR) error conditions
1190 4 (KERN_WARNING) warning conditions
1191 5 (KERN_NOTICE) normal but significant condition
1192 6 (KERN_INFO) informational
1193 7 (KERN_DEBUG) debug-level messages
1194
1195 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001196 Format: { n | nk | nM }
1197 n must be a power of two. The default size
1198 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199
Randy Dunlapaccaa242007-10-16 01:29:37 -07001200 logo.nologo [FB] Disables display of the built-in Linux logo.
1201 This may be used to provide more screen space for
1202 kernel log messages and is useful when debugging
1203 kernel boot problems.
1204
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 lp=0 [LP] Specify parallel ports to use, e.g,
1206 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1207 lp=reset first parallel port). 'lp=0' disables the
1208 lp=auto printer driver. 'lp=reset' (which can be
1209 specified in addition to the ports) causes
1210 attached printers to be reset. Using
1211 lp=port1,port2,... specifies the parallel ports
1212 to associate lp devices with, starting with
1213 lp0. A port specification may be 'none' to skip
1214 that lp device, or a parport name such as
1215 'parport0'. Specifying 'lp=auto' instead of a
1216 port specification list means that device IDs
1217 from each port should be examined, to see if
1218 an IEEE 1284-compliant printer is attached; if
1219 so, the driver will manage that printer.
1220 See also header of drivers/char/lp.c.
1221
1222 lpj=n [KNL]
1223 Sets loops_per_jiffy to given constant, thus avoiding
1224 time-consuming boot-time autodetection (up to 250 ms per
1225 CPU). 0 enables autodetection (default). To determine
1226 the correct value for your kernel, boot with normal
1227 autodetection and see what value is printed. Note that
1228 on SMP systems the preset will be applied to all CPUs,
1229 which is likely to cause problems if your CPUs need
1230 significantly divergent settings. An incorrect value
1231 will cause delays in the kernel to be wrong, leading to
1232 unpredictable I/O errors and other breakage. Although
1233 unlikely, in the extreme case this might damage your
1234 hardware.
1235
1236 ltpc= [NET]
1237 Format: <io>,<irq>,<dma>
1238
Randy Dunlapa9913042005-10-23 12:57:11 -07001239 mac5380= [HW,SCSI] Format:
1240 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241
Randy Dunlapa9913042005-10-23 12:57:11 -07001242 machvec= [IA64] Force the use of a particular machine-vector
1243 (machvec) in a generic kernel.
1244 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001246 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1247 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248
1249 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001250 should make use of. maxcpus=n : n >= 0 limits the
1251 kernel to using 'n' processors. n=0 is a special case,
1252 it is equivalent to "nosmp", which also disables
1253 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001255 max_loop= [LOOP] Maximum number of loopback devices that can
1256 be mounted
1257 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001258
Randy Dunlapa9913042005-10-23 12:57:11 -07001259 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260 Should be between 1 and 2^32-1.
1261
1262 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001263 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 Should be between 1 and 16384.
1265
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 mcatest= [IA-64]
1267
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001268 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269
Uwe Hermann71cced62008-10-20 09:32:21 -07001270 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001271
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 md= [HW] RAID subsystems devices and level
1273 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001274
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275 mdacon= [MDA]
1276 Format: <first>,<last>
1277 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001278
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1280 Amount of memory to be used when the kernel is not able
1281 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001282 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 address space collisions. Without memmap= PCI devices
1284 could be placed at addresses belonging to unused RAM.
1285
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001286 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 memory.
1288
Paul Mundt6902aa82008-09-21 17:14:42 +09001289 memchunk=nn[KMG]
1290 [KNL,SH] Allow user to override the default size for
1291 per-device physically contiguous DMA buffers.
1292
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301293 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 E820 memory map, as specified by the user.
1295 Such memmap=exactmap lines can be constructed based on
1296 BIOS output or other requirements. See the memmap=nn@ss
1297 option description.
1298
1299 memmap=nn[KMG]@ss[KMG]
1300 [KNL] Force usage of a specific region of memory
1301 Region of memory to be used, from ss to ss+nn.
1302
1303 memmap=nn[KMG]#ss[KMG]
1304 [KNL,ACPI] Mark specific memory as ACPI data.
1305 Region of memory to be used, from ss to ss+nn.
1306
1307 memmap=nn[KMG]$ss[KMG]
1308 [KNL,ACPI] Mark specific memory as reserved.
1309 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001310 Example: Exclude memory from 0x18690000-0x1869ffff
1311 memmap=64K$0x18690000
1312 or
1313 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001315 memory_corruption_check=0/1 [X86]
1316 Some BIOSes seem to corrupt the first 64k of
1317 memory when doing things like suspend/resume.
1318 Setting this option will scan the memory
1319 looking for corruption. Enabling this will
1320 both detect corruption and prevent the kernel
1321 from using the memory being corrupted.
1322 However, its intended as a diagnostic tool; if
1323 repeatable BIOS-originated corruption always
1324 affects the same memory, you can use memmap=
1325 to prevent the kernel from using that memory.
1326
1327 memory_corruption_check_size=size [X86]
1328 By default it checks for corruption in the low
1329 64k, making this memory unavailable for normal
1330 use. Use this parameter to scan for
1331 corruption in more or less memory.
1332
1333 memory_corruption_check_period=seconds [X86]
1334 By default it checks for corruption every 60
1335 seconds. Use this parameter to check at some
1336 other rate. 0 disables periodic checking.
1337
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001338 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001339 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001340 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001341 Specifies the number of memtest passes to be
1342 performed. Each pass selects another test
1343 pattern from a given set of patterns. Memtest
1344 fills the memory with this pattern, validates
1345 memory contents and reserves bad memory
1346 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001347
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 meye.*= [HW] Set MotionEye Camera parameters
1349 See Documentation/video4linux/meye.txt.
1350
Andres Salomon8f368812007-10-12 23:04:06 +02001351 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1352 Multi-Function General Purpose Timers on AMD Geode
1353 platforms.
1354
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001355 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1356 the BIOS has incorrectly applied a workaround. TinyBIOS
1357 version 0.98 is known to be affected, 0.99 fixes the
1358 problem by letting the user disable the workaround.
1359
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 mga= [HW,DRM]
1361
Randy Dunlap1c207f92008-11-19 15:36:16 -08001362 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1363 physical address is ignored.
1364
Michel Pollet39f45d72009-05-20 11:10:31 +01001365 mini2440= [ARM,HW,KNL]
1366 Format:[0..2][b][c][t]
1367 Default: "0tb"
1368 MINI2440 configuration specification:
1369 0 - The attached screen is the 3.5" TFT
1370 1 - The attached screen is the 7" TFT
1371 2 - The VGA Shield is attached (1024x768)
1372 Leaving out the screen size parameter will not load
1373 the TFT driver, and the framebuffer will be left
1374 unconfigured.
1375 b - Enable backlight. The TFT backlight pin will be
1376 linked to the kernel VESA blanking code and a GPIO
1377 LED. This parameter is not necessary when using the
1378 VGA shield.
1379 c - Enable the s3c camera interface.
1380 t - Reserved for enabling touchscreen support. The
1381 touchscreen support is not enabled in the mainstream
1382 kernel as of 2.6.30, a preliminary port can be found
1383 in the "bleeding edge" mini2440 support kernel at
1384 http://repo.or.cz/w/linux-2.6/mini2440.git
1385
Mel Gorman6b74ab92008-07-23 21:26:49 -07001386 mminit_loglevel=
1387 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1388 parameter allows control of the logging verbosity for
1389 the additional memory initialisation checks. A value
1390 of 0 disables mminit logging and a level of 4 will
1391 log everything. Information is printed at KERN_DEBUG
1392 so loglevel=8 may also need to be specified.
1393
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 mousedev.tap_time=
1395 [MOUSE] Maximum time between finger touching and
1396 leaving touchpad surface for touch to be considered
1397 a tap and be reported as a left button click (for
1398 touchpads working in absolute mode only).
1399 Format: <msecs>
1400 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1401 reporting absolute coordinates, such as tablets
1402 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1403 reporting absolute coordinates, such as tablets
1404
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301405 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001406 is similar to kernelcore except it specifies the
1407 amount of memory used for migratable allocations.
1408 If both kernelcore and movablecore is specified,
1409 then kernelcore will be at *least* the specified
1410 value but may be more. If movablecore on its own
1411 is specified, the administrator must be careful
1412 that the amount of memory usable for all allocations
1413 is not too small.
1414
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 mpu401= [HW,OSS]
1416 Format: <io>,<irq>
1417
1418 MTD_Partition= [MTD]
1419 Format: <name>,<region-number>,<size>,<offset>
1420
Randy Dunlapa9913042005-10-23 12:57:11 -07001421 MTD_Region= [MTD] Format:
1422 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423
1424 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001425 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001427 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1428
1429 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1430
1431 boundary - index of last SLC block on Flex-OneNAND.
1432 The remaining blocks are configured as MLC blocks.
1433 lock - Configure if Flex-OneNAND boundary should be locked.
1434 Once locked, the boundary cannot be changed.
1435 1 indicates lock status, 0 indicates unlock status.
1436
Ben Dooks9db829f2008-07-03 11:24:29 +01001437 mtdset= [ARM]
1438 ARM/S3C2412 JIVE boot control
1439
1440 See arch/arm/mach-s3c2412/mach-jive.c
1441
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001443 [HW] Make the MicroTouch USB driver use raw coordinates
1444 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001446 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001447 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001448 that could hold holes aka. UC entries.
1449
1450 mtrr_gran_size=nn[KMG] [X86]
1451 Used for mtrr cleanup. It is granularity of mtrr block.
1452 Default is 1.
1453 Large value could prevent small alignment from
1454 using up MTRRs.
1455
1456 mtrr_spare_reg_nr=n [X86]
1457 Format: <integer>
1458 Range: 0,7 : spare reg number
1459 Default : 1
1460 Used for mtrr cleanup. It is spare mtrr entries number.
1461 Set to 2 or more if your graphical card needs more.
1462
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1464
1465 NCR_D700= [HW,SCSI]
1466 See header of drivers/scsi/NCR_D700.c.
1467
1468 ncr5380= [HW,SCSI]
1469
1470 ncr53c400= [HW,SCSI]
1471
1472 ncr53c400a= [HW,SCSI]
1473
1474 ncr53c406a= [HW,SCSI]
1475
1476 ncr53c8xx= [HW,SCSI]
1477
1478 netdev= [NET] Network devices parameters
1479 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1480 Note that mem_start is often overloaded to mean
1481 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001482 This usage is only documented in each driver source
1483 file if at all.
1484
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001485 nf_conntrack.acct=
1486 [NETFILTER] Enable connection tracking flow accounting
1487 0 to disable accounting
1488 1 to enable accounting
1489 Default value depends on CONFIG_NF_CT_ACCT that is
1490 going to be removed in 2.6.29.
1491
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001493 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494
1495 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001496 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497
Trond Myklebusta72b4422006-01-03 09:55:41 +01001498 nfs.callback_tcpport=
1499 [NFS] set the TCP port on which the NFSv4 callback
1500 channel should listen.
1501
Trond Myklebust58df0952006-01-03 09:55:57 +01001502 nfs.idmap_cache_timeout=
1503 [NFS] set the maximum lifetime for idmapper cache
1504 entries.
1505
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001506 nfs.enable_ino64=
1507 [NFS] enable 64-bit inode numbers.
1508 If zero, the NFS client will fake up a 32-bit inode
1509 number for the readdir() and stat() syscalls instead
1510 of returning the full 64-bit number.
1511 The default is to return 64-bit inode numbers.
1512
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001513 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1514 when a NMI is triggered.
1515 Format: [state][,regs][,debounce][,die]
1516
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301517 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001518 Format: [panic,][num]
1519 Valid num: 0,1,2
1520 0 - turn nmi_watchdog off
1521 1 - use the IO-APIC timer for the NMI watchdog
1522 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001523 a performance counter. Note: This will use one
1524 performance counter and the local APIC's performance
1525 vector.
1526 When panic is specified, panic when an NMI watchdog
1527 timeout occurs.
1528 This is useful when you use a panic=... timeout and
1529 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001530 Instead of 1 and 2 it is possible to use the following
1531 symbolic names: lapic and ioapic
1532 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
Anton Vorontsovbff38772009-07-08 11:10:56 -07001534 netpoll.carrier_timeout=
1535 [NET] Specifies amount of time (in seconds) that
1536 netpoll should wait for a carrier. By default netpoll
1537 waits 4 seconds.
1538
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001539 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 emulation library even if a 387 maths coprocessor
1541 is present.
1542
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001543 no_console_suspend
1544 [HW] Never suspend the console
1545 Disable suspending of consoles during suspend and
1546 hibernate operations. Once disabled, debugging
1547 messages can reach various consoles while the rest
1548 of the system is being put to sleep (ie, while
1549 debugging driver suspend/resume hooks). This may
1550 not work reliably with all consoles, but is known
1551 to work with serial and VGA consoles.
1552
Christoph Lameterc1aee212007-05-31 00:40:47 -07001553 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1554 caches in the slab allocator. Saves per-node memory,
1555 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001556
Randy Dunlapa9913042005-10-23 12:57:11 -07001557 noalign [KNL,ARM]
1558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 noapic [SMP,APIC] Tells the kernel to not make use of any
1560 IOAPICs that may be present in the system.
1561
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 nobats [PPC] Do not use BATs for mapping kernel lowmem
1563 on "Classic" PPC cores.
1564
1565 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001566
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001567 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1568
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001569 nodelayacct [KNL] Disable per-task delay accounting
1570
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1572
Paul Mundt6902aa82008-09-21 17:14:42 +09001573 nodsp [SH] Disable hardware DSP at boot time.
1574
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301575 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001576
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 noexec [IA-64]
1578
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301579 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001580 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001582 noexec=off: disable non-executable mappings
1583
1584 noexec32 [X86-64]
1585 This affects only 32-bit executables.
1586 noexec32=on: enable non-executable mappings (default)
1587 read doesn't imply executable mappings
1588 noexec32=off: disable non-executable mappings
1589 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590
Paul Mundt6902aa82008-09-21 17:14:42 +09001591 nofpu [SH] Disable hardware FPU at boot time.
1592
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001593 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001594 register save and restore. The kernel will only save
1595 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596
Suresh Siddha0c752a92009-05-22 12:17:45 -07001597 noxsave [BUGS=X86] Disables x86 extended register state save
1598 and restore using xsave. The kernel will fallback to
1599 enabling legacy floating-point and sse state.
1600
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001601 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1602 wfi(ARM) instruction doesn't work correctly and not to
1603 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001604
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001605 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606 instruction doesn't work correctly and not to
1607 use it.
1608
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001609 no_file_caps Tells the kernel not to honor file capabilities. The
1610 only way then for a file to be executed with privilege
1611 is to be setuid root or executed by root.
1612
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 nohalt [IA-64] Tells the kernel not to use the power saving
1614 function PAL_HALT_LIGHT when idle. This increases
1615 power-consumption. On the positive side, it reduces
1616 interrupt wake-up latency, which may improve performance
1617 in certain environments such as networked servers or
1618 real-time systems.
1619
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001620 nohz= [KNL] Boottime enable/disable dynamic ticks
1621 Valid arguments: on, off
1622 Default: on
1623
Paul Mundteeee7852009-04-02 12:31:16 +09001624 noiotrap [SH] Disables trapped I/O port accesses.
1625
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001626 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 disable unhandled interrupt sources.
1628
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301629 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001630 broken timer IRQ sources.
1631
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 noisapnp [ISAPNP] Disables ISA PnP code.
1633
1634 noinitrd [RAM] Tells the kernel not to load any configured
1635 initial RAM disk.
1636
Weidong Han03ea8152009-04-17 16:42:15 +08001637 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1638 remapping.
1639
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 nointroute [IA-64]
1641
Tony Luck0aa366f2007-07-20 11:22:30 -07001642 nojitter [IA64] Disables jitter checking for ITC timers.
1643
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001644 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001646 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001647
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 noltlbs [PPC] Do not use large page/tlb entries for kernel
1649 lowmem mapping on PPC40x.
1650
Horms312f1f02006-02-22 09:57:55 +09001651 nomca [IA-64] Disable machine check abort handling
1652
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001653 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001654
Andres Salomon83d73842007-10-12 23:04:06 +02001655 nomfgpt [X86-32] Disable Multi-Function General Purpose
1656 Timer usage (for AMD Geode machines).
1657
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001658 norandmaps Don't use address space randomization. Equivalent to
1659 echo 0 > /proc/sys/kernel/randomize_va_space
1660
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001661 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001662
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001663 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001664 with UP alternatives
1665
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666 noresidual [PPC] Don't use residual data on PReP machines.
1667
Randy Dunlapa9913042005-10-23 12:57:11 -07001668 noresume [SWSUSP] Disables resume and restores original swap
1669 space.
1670
Linus Torvalds1da177e2005-04-16 15:20:36 -07001671 no-scroll [VGA] Disables scrollback.
1672 This is required for the Braillex ib80-piezo Braille
1673 reader made by F.H. Papenmeier (Germany).
1674
1675 nosbagart [IA-64]
1676
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001677 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001678
Len Brown61ec7562007-08-16 03:34:22 -04001679 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1680 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681
Dave Jones97842212007-07-15 23:41:05 -07001682 nosoftlockup [KNL] Disable the soft-lockup detector.
1683
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001684 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001685 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 nosync [HW,M68K] Disables sync negotiation for all devices.
1688
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001689 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690
1691 nousb [USB] Disable the USB subsystem
1692
1693 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001694
Weidong Han2b2fd872009-04-17 16:42:12 +08001695 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1696
Fenghua Yua6c75b862008-03-14 13:57:08 -07001697 nptcg= [IA64] Override max number of concurrent global TLB
1698 purges which is reported from either PAL_VM_SUMMARY or
1699 SAL PALO.
1700
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001701 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1702
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001703 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1704 one of ['zone', 'node', 'default'] can be specified
1705 This can be set from sysctl after boot.
1706 See Documentation/sysctl/vm.txt for details.
1707
Randy Dunlap7c4be252009-01-06 14:42:44 -08001708 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1709 See Documentation/debugging-via-ohci1394.txt for more
1710 info.
1711
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001712 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1713 Rather than timing out after 20 ms if an EC
1714 command is not properly ACKed, override the length
1715 of the timeout. We have interrupts disabled while
1716 waiting for the ACK, so if this is set too high
1717 interrupts *may* be lost!
1718
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 opl3= [HW,OSS]
1720 Format: <io>
1721
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 oprofile.timer= [HW]
1723 Use timer interrupt instead of performance counters
1724
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001725 oprofile.cpu_type= Force an oprofile cpu type
1726 This might be useful if you have an older oprofile
1727 userland or if you want common events.
1728 Format: { archperfmon }
1729 archperfmon: [X86] Force use of architectural
1730 perfmon on Intel CPUs instead of the
1731 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001732
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 osst= [HW,SCSI] SCSI Tape Driver
1734 Format: <buffer_size>,<write_threshold>
1735 See also Documentation/scsi/st.txt.
1736
1737 panic= [KNL] Kernel behaviour on panic
1738 Format: <timeout>
1739
1740 parkbd.port= [HW] Parallel port number the keyboard adapter is
1741 connected to, default is 0.
1742 Format: <parport#>
1743 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1744 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001745 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746
Randy Dunlapa9913042005-10-23 12:57:11 -07001747 parport= [HW,PPT] Specify parallel ports. 0 disables.
1748 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1749 Use 'auto' to force the driver to use any
1750 IRQ/DMA settings detected (the default is to
1751 ignore detected IRQ/DMA settings because of
1752 possible conflicts). You can specify the base
1753 address, IRQ, and DMA settings; IRQ and DMA
1754 should be numbers, or 'auto' (for using detected
1755 settings on that particular port), or 'nofifo'
1756 (to avoid using a FIFO even if it is detected).
1757 Parallel ports are assigned in the order they
1758 are specified on the command line, starting
1759 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760
Randy Dunlapa9913042005-10-23 12:57:11 -07001761 parport_init_mode= [HW,PPT]
1762 Configure VIA parallel port to operate in
1763 a specific mode. This is necessary on Pegasos
1764 computer where firmware has no options for setting
1765 up parallel port mode and sets it to spp.
1766 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 Format: [spp|ps2|epp|ecp|ecpepp]
1768
Randy Dunlapa9913042005-10-23 12:57:11 -07001769 pas2= [HW,OSS] Format:
1770 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1771
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772 pas16= [HW,SCSI]
1773 See header of drivers/scsi/pas16.c.
1774
Andrew Mortondd287792006-03-23 03:00:57 -08001775 pause_on_oops=
1776 Halt all CPUs after the first oops has been printed for
1777 the specified number of seconds. This is to be used if
1778 your oopses keep scrolling off the screen.
1779
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 pcbit= [HW,ISDN]
1781
1782 pcd. [PARIDE]
1783 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001784 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785
Randy Dunlapa9913042005-10-23 12:57:11 -07001786 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001787 earlydump [X86] dump PCI config space before the kernel
1788 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001789 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001790 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001791 the hardware directly. Use this if your machine
1792 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001793 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001794 hardware access methods are allowed. Use this
1795 if you experience crashes upon bootup and you
1796 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001797 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001798 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001799 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001800 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001801 noaer [PCIE] If the PCIEAER kernel config parameter is
1802 enabled, this kernel boot option can be used to
1803 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001804 nodomains [PCI] Disable support for multiple PCI
1805 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301806 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001807 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001808 check_enable_amd_mmconf [X86] check for and enable
1809 properly configured MMIO access to PCI
1810 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001811 nomsi [MSI] If the PCI_MSI kernel config parameter is
1812 enabled, this kernel boot option can be used to
1813 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001814 noioapicquirk [APIC] Disable all boot interrupt quirks.
1815 Safety option to keep boot IRQs enabled. This
1816 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001817 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1818 primary IO-APIC for bridges that cannot disable
1819 boot IRQs. This fixes a source of spurious IRQs
1820 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001821 noioapicreroute [APIC] Disable workaround that uses the
1822 boot IRQ equivalent of an IRQ that connects to
1823 a chipset where boot IRQs cannot be disabled.
1824 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001825 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001826 routing table. These calls are known to be buggy
1827 on several machines and they hang the machine
1828 when used, but on other computers it's the only
1829 way to get the interrupt routing table. Try
1830 this option if the kernel is unable to allocate
1831 IRQs or discover secondary PCI buses on your
1832 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001833 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001834 Use with caution as certain devices share
1835 address decoders between ROMs and other
1836 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001837 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001838 expansion ROMs that do not already have
1839 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001840 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001841 assigned automatically to PCI devices. You can
1842 make the kernel exclude IRQs of your ISA cards
1843 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001844 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001845 of the PIRQ table (normally generated
1846 by the BIOS) if it is outside the
1847 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001848 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001849 useful if the kernel is unable to find your
1850 secondary buses and you want to tell it
1851 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001852 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001853 numbers ourselves, overriding
1854 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001855 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001856 in the BIOS $PIR table. This is needed on
1857 some systems with broken BIOSes, notably
1858 some HP Pavilion N5400 and Omnibook XE3
1859 notebooks. This will have no effect if ACPI
1860 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001861 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001862 or for PCI scanning.
Linus Torvalds236e9462009-06-24 16:23:03 -07001863 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001864 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001865 routeirq Do IRQ routing for all PCI devices.
1866 This is normally done in pci_enable_device(),
1867 so this option is a temporary workaround
1868 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001869 skip_isa_align [X86] do not align io start addr, so can
1870 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001871 firmware [ARM] Do not re-enumerate the bus but instead
1872 just use the configuration from the
1873 bootloader. This is currently used on
1874 IXP2000 systems where the bus has to be
1875 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001876 noearly [X86] Don't do any early type 1 scanning.
1877 This might help on some broken boards which
1878 machine check when some devices' config space
1879 is read. But various workarounds are disabled
1880 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001881 bfsort Sort PCI devices into breadth-first order.
1882 This sorting is done to get a device
1883 order compatible with older (<= 2.4) kernels.
1884 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001885 cbiosize=nn[KMG] The fixed amount of bus space which is
1886 reserved for the CardBus bridge's IO window.
1887 The default value is 256 bytes.
1888 cbmemsize=nn[KMG] The fixed amount of bus space which is
1889 reserved for the CardBus bridge's memory
1890 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09001891 resource_alignment=
1892 Format:
1893 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1894 Specifies alignment and device to reassign
1895 aligned memory resources.
1896 If <order of align> is not specified,
1897 PAGE_SIZE is used as alignment.
1898 PCI-PCI bridge can be specified, if resource
1899 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06001900 ecrc= Enable/disable PCIe ECRC (transaction layer
1901 end-to-end CRC checking).
1902 bios: Use BIOS/firmware settings. This is the
1903 the default.
1904 off: Turn ECRC off
1905 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001906
Chuck Ebberte5665a42008-09-24 20:40:34 -04001907 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1908 Management.
1909 off Disable ASPM.
1910 force Enable ASPM even on devices that claim not to support it.
1911 WARNING: Forcing ASPM on may cause system lockups.
1912
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 pcmv= [HW,PCMCIA] BadgePAD 4
1914
1915 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001916 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917
1918 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1919 boot time.
1920 Format: { 0 | 1 }
1921 See arch/parisc/kernel/pdc_chassis.c
1922
Tejun Heofa8a7092009-06-22 11:56:24 +09001923 percpu_alloc= [X86] Select which percpu first chunk allocator to use.
1924 Allowed values are one of "lpage", "embed" and "4k".
1925 See comments in arch/x86/kernel/setup_percpu.c for
1926 details on each allocator. This parameter is primarily
1927 for debugging and performance comparison.
1928
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001930 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931
1932 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001933 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934
1935 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001936 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
1938 plip= [PPT,NET] Parallel port network link
1939 Format: { parport<nr> | timid | 0 }
1940 See also Documentation/parport.txt.
1941
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001942 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1943 Override pmtimer IOPort with a hex value.
1944 e.g. pmtmr=0x508
1945
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001946 pnp.debug [PNP]
1947 Enable PNP debug messages. This depends on the
1948 CONFIG_PNP_DEBUG_MESSAGES option.
1949
Linus Torvalds1da177e2005-04-16 15:20:36 -07001950 pnpacpi= [ACPI]
1951 { off }
1952
1953 pnpbios= [ISAPNP]
1954 { on | off | curr | res | no-curr | no-res }
1955
1956 pnp_reserve_irq=
1957 [ISAPNP] Exclude IRQs for the autoconfiguration
1958
1959 pnp_reserve_dma=
1960 [ISAPNP] Exclude DMAs for the autoconfiguration
1961
1962 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001963 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964
1965 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001966 [ISAPNP] Exclude memory regions for the
1967 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 Ranges are in pairs (memory base and size).
1969
Randy Dunlap4af94f32009-04-17 18:30:28 -07001970 ports= [IP_VS_FTP] IPVS ftp helper module
1971 Default is 21.
1972 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1973 may be specified.
1974 Format: <port>,<port>....
1975
Ingo Molnar45807a12007-07-15 23:40:10 -07001976 print-fatal-signals=
1977 [KNL] debug: print fatal signals
1978 print-fatal-signals=1: print segfault info to
1979 the kernel console.
1980 default: off.
1981
Randy Dunlape84845c2007-07-15 23:40:25 -07001982 printk.time= Show timing data prefixed to each printk message line
1983 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1984
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001985 processor.max_cstate= [HW,ACPI]
1986 Limit processor to maximum C-state
1987 max_cstate=9 overrides any DMI blacklist limit.
1988
1989 processor.nocst [HW,ACPI]
1990 Ignore the _CST method to determine C-states,
1991 instead using the legacy FADT method
1992
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001994 Format: [schedule,]<number>
1995 Param: "schedule" - profile schedule points.
1996 Param: <number> - step/bucket size as a power of 2 for
1997 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001998 Param: "sleep" - profile D-state sleeping (millisecs).
1999 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002000 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2003 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002004 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005
Randy Dunlapa9913042005-10-23 12:57:11 -07002006 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2007 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2009 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002010 psmouse.resetafter= [HW,MOUSE]
2011 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012 (0 = never).
2013 psmouse.resolution=
2014 [HW,MOUSE] Set desired mouse resolution, in dpi.
2015 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002016 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 0 = disabled, 1 = enabled (default).
2018
2019 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002020 Format:
2021 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022
2023 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002024 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002025
Kay Sieversdc8c8582007-08-15 12:25:38 +02002026 pty.legacy_count=
2027 [KNL] Number of legacy pty's. Overwrites compiled-in
2028 default number.
2029
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002030 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 r128= [HW,DRM]
2033
2034 raid= [HW,RAID]
2035 See Documentation/md.txt.
2036
Randy Dunlapa9913042005-10-23 12:57:11 -07002037 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002038 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002039
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002041 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002043 rcupdate.blimit= [KNL,BOOT]
2044 Set maximum number of finished RCU callbacks to process
2045 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002046
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002047 rcupdate.qhimark= [KNL,BOOT]
2048 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002049 RCU callbacks over which batch limiting is disabled.
2050
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002051 rcupdate.qlowmark= [KNL,BOOT]
2052 Set threshold of queued RCU callbacks below which
2053 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002054
Olof Johanssonffdfc402005-09-06 15:17:19 -07002055 rdinit= [KNL]
2056 Format: <full_path>
2057 Run specified binary instead of /init from the ramdisk,
2058 used for early userspace startup. See initrd.
2059
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002060 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002062 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063
Paul Jackson46b6d942008-07-04 10:00:09 -07002064 relax_domain_level=
2065 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002066 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002067
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2069
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002070 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002071 Format: nn[KMG]
2072 Reserves a hole at the top of the kernel virtual
2073 address space.
2074
Vivek Goyal7e962872006-09-27 01:50:44 -07002075 reset_devices [KNL] Force drivers to reset the underlying device
2076 during initialization.
2077
Randy Dunlapa9913042005-10-23 12:57:11 -07002078 resume= [SWSUSP]
2079 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002081 resume_offset= [SWSUSP]
2082 Specify the offset from the beginning of the partition
2083 given by "resume=" at which the swap header is located,
2084 in <PAGE_SIZE> units (needed only for swap files).
2085 See Documentation/power/swsusp-and-swap-files.txt
2086
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002087 retain_initrd [RAM] Keep initrd memory after extraction
2088
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 rhash_entries= [KNL,NET]
2090 Set number of hash buckets for route cache
2091
2092 riscom8= [HW,SERIAL]
2093 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2094
2095 ro [KNL] Mount root device read-only on boot
2096
2097 root= [KNL] Root filesystem
2098
2099 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2100 mount the root filesystem
2101
2102 rootflags= [KNL] Set root filesystem mount option string
2103
2104 rootfstype= [KNL] Set root filesystem type
2105
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002106 rootwait [KNL] Wait (indefinitely) for root device to show up.
2107 Useful for devices that are detected asynchronously
2108 (e.g. USB and MMC devices).
2109
James Morris20510f22007-10-16 23:31:32 -07002110 root_plug.vendor_id=
2111 [ROOTPLUG] Override the default vendor ID
2112
2113 root_plug.product_id=
2114 [ROOTPLUG] Override the default product ID
2115
2116 root_plug.debug=
2117 [ROOTPLUG] Enable debugging output
2118
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119 rw [KNL] Mount root device read-write on boot
2120
2121 S [KNL] Run init in single mode
2122
2123 sa1100ir [NET]
2124 See drivers/net/irda/sa1100_ir.c.
2125
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002127
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2129 Format: <io>[,<timeout>[,<isapnp>]]
2130
2131 scsi_debug_*= [SCSI]
2132 See drivers/scsi/scsi_debug.c.
2133
2134 scsi_default_dev_flags=
2135 [SCSI] SCSI default device flags
2136 Format: <integer>
2137
2138 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2139 Format: <vendor>:<model>:<flags>
2140 (flags are integer value)
2141
Randy Dunlap6af66322007-11-14 16:52:25 -08002142 scsi_logging_level= [SCSI] a bit mask of logging levels
2143 See drivers/scsi/scsi_logging.h for bits. Also
2144 settable via sysctl at dev.scsi.logging_level
2145 (/proc/sys/dev/scsi/logging_level).
2146 There is also a nice 'scsi_logging_level' script in the
2147 S390-tools package, available for download at
2148 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002150 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2151 discovered. async scans them in kernel threads,
2152 allowing boot to proceed. none ignores them, expecting
2153 user space to do the scan.
2154
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002155 security= [SECURITY] Choose a security module to enable at boot.
2156 If this boot parameter is not specified, only the first
2157 security module asking for security registration will be
2158 loaded. An invalid security module name will be treated
2159 as if no module has been chosen.
2160
2161 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162 Format: { "0" | "1" }
2163 See security/selinux/Kconfig help text.
2164 0 -- disable.
2165 1 -- enable.
2166 Default value is set via kernel config option.
2167 If enabled at boot time, /selinux/disable can be used
2168 later to disable prior to initial policy load.
2169
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002170 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 shapers= [NET]
2173 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002174
Yinghai Lub05f78f2008-08-22 01:32:50 -07002175 show_msr= [x86] show boot-time MSR settings
2176 Format: { <integer> }
2177 Show boot-time (BIOS-initialized) MSR settings.
2178 The parameter means the number of CPUs to show,
2179 for example 1 means boot CPU only.
2180
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 sim710= [SCSI,HW]
2182 See header of drivers/scsi/sim710.c.
2183
2184 simeth= [IA-64]
2185 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002186
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187 slram= [HW,MTD]
2188
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002189 slub_debug[=options[,slabs]] [MM, SLUB]
2190 Enabling slub_debug allows one to determine the
2191 culprit if slab objects become corrupted. Enabling
2192 slub_debug can create guard zones around objects and
2193 may poison objects when not in use. Also tracks the
2194 last alloc / free. For more information see
2195 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002196
2197 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002198 Determines the maximum allowed order for slabs.
2199 A high setting may cause OOMs due to memory
2200 fragmentation. For more information see
2201 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002202
2203 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002204 The minimum number of objects per slab. SLUB will
2205 increase the slab order up to slub_max_order to
2206 generate a sufficiently large slab able to contain
2207 the number of objects indicated. The higher the number
2208 of objects the smaller the overhead of tracking slabs
2209 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002210 For more information see Documentation/vm/slub.txt.
2211
2212 slub_min_order= [MM, SLUB]
2213 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002214 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002215 For more information see Documentation/vm/slub.txt.
2216
2217 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002218 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002219 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002220 allocs to different slabs. Debug options disable
2221 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002222 For more information see Documentation/vm/slub.txt.
2223
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 smart2= [HW]
2225 Format: <io1>[,<io2>[,...,<io8>]]
2226
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002227 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002228 attempt to substitute SMP alternatives once at boot.
2229
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002230 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2231 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2232 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2233 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2234 smsc-ircc2.ircc_irq= [HW] IRQ line
2235 smsc-ircc2.ircc_dma= [HW] DMA channel
2236 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2237 0: Toshiba Satellite 1800 (GP data pin select)
2238 1: Fast pin select (default)
2239 2: ATC IRMode
2240
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 snd-ad1816a= [HW,ALSA]
2242
2243 snd-ad1848= [HW,ALSA]
2244
2245 snd-ali5451= [HW,ALSA]
2246
2247 snd-als100= [HW,ALSA]
2248
2249 snd-als4000= [HW,ALSA]
2250
2251 snd-azt2320= [HW,ALSA]
2252
2253 snd-cmi8330= [HW,ALSA]
2254
2255 snd-cmipci= [HW,ALSA]
2256
2257 snd-cs4231= [HW,ALSA]
2258
2259 snd-cs4232= [HW,ALSA]
2260
2261 snd-cs4236= [HW,ALSA]
2262
2263 snd-cs4281= [HW,ALSA]
2264
2265 snd-cs46xx= [HW,ALSA]
2266
2267 snd-dt019x= [HW,ALSA]
2268
2269 snd-dummy= [HW,ALSA]
2270
2271 snd-emu10k1= [HW,ALSA]
2272
2273 snd-ens1370= [HW,ALSA]
2274
2275 snd-ens1371= [HW,ALSA]
2276
2277 snd-es968= [HW,ALSA]
2278
2279 snd-es1688= [HW,ALSA]
2280
2281 snd-es18xx= [HW,ALSA]
2282
2283 snd-es1938= [HW,ALSA]
2284
2285 snd-es1968= [HW,ALSA]
2286
2287 snd-fm801= [HW,ALSA]
2288
2289 snd-gusclassic= [HW,ALSA]
2290
2291 snd-gusextreme= [HW,ALSA]
2292
2293 snd-gusmax= [HW,ALSA]
2294
2295 snd-hdsp= [HW,ALSA]
2296
2297 snd-ice1712= [HW,ALSA]
2298
2299 snd-intel8x0= [HW,ALSA]
2300
2301 snd-interwave= [HW,ALSA]
2302
2303 snd-interwave-stb=
2304 [HW,ALSA]
2305
2306 snd-korg1212= [HW,ALSA]
2307
2308 snd-maestro3= [HW,ALSA]
2309
2310 snd-mpu401= [HW,ALSA]
2311
2312 snd-mtpav= [HW,ALSA]
2313
2314 snd-nm256= [HW,ALSA]
2315
2316 snd-opl3sa2= [HW,ALSA]
2317
2318 snd-opti92x-ad1848=
2319 [HW,ALSA]
2320
2321 snd-opti92x-cs4231=
2322 [HW,ALSA]
2323
2324 snd-opti93x= [HW,ALSA]
2325
2326 snd-pmac= [HW,ALSA]
2327
2328 snd-rme32= [HW,ALSA]
2329
2330 snd-rme96= [HW,ALSA]
2331
2332 snd-rme9652= [HW,ALSA]
2333
2334 snd-sb8= [HW,ALSA]
2335
2336 snd-sb16= [HW,ALSA]
2337
2338 snd-sbawe= [HW,ALSA]
2339
2340 snd-serial= [HW,ALSA]
2341
2342 snd-sgalaxy= [HW,ALSA]
2343
2344 snd-sonicvibes= [HW,ALSA]
2345
2346 snd-sun-amd7930=
2347 [HW,ALSA]
2348
2349 snd-sun-cs4231= [HW,ALSA]
2350
2351 snd-trident= [HW,ALSA]
2352
2353 snd-usb-audio= [HW,ALSA,USB]
2354
2355 snd-via82xx= [HW,ALSA]
2356
2357 snd-virmidi= [HW,ALSA]
2358
2359 snd-wavefront= [HW,ALSA]
2360
2361 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002362
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002363 softlockup_panic=
2364 [KNL] Should the soft-lockup detector generate panics.
2365
Linus Torvalds1da177e2005-04-16 15:20:36 -07002366 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2367 See Documentation/sonypi.txt
2368
2369 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002370 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371
2372 spia_io_base= [HW,MTD]
2373 spia_fio_base=
2374 spia_pedr=
2375 spia_peddr=
2376
2377 sscape= [HW,OSS]
2378 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002379
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2381 See Documentation/scsi/st.txt.
2382
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002383 stacktrace [FTRACE]
2384 Enabled the stack tracer on boot up.
2385
Linus Torvalds1da177e2005-04-16 15:20:36 -07002386 sti= [PARISC,HW]
2387 Format: <num>
2388 Set the STI (builtin display/keyboard on the HP-PARISC
2389 machines) console (graphic card) which should be used
2390 as the initial boot-console.
2391 See also comment in drivers/video/console/sticore.c.
2392
2393 sti_font= [HW]
2394 See comment in drivers/video/console/sticore.c.
2395
2396 stifb= [HW]
2397 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2398
Greg Banks42a7fc42007-03-06 01:42:23 -08002399 sunrpc.pool_mode=
2400 [NFS]
2401 Control how the NFS server code allocates CPUs to
2402 service thread pools. Depending on how many NICs
2403 you have and where their interrupts are bound, this
2404 option will affect which CPUs will do NFS serving.
2405 Note: this parameter cannot be changed while the
2406 NFS server is running.
2407
2408 auto the server chooses an appropriate mode
2409 automatically using heuristics
2410 global a single global pool contains all CPUs
2411 percpu one pool for each CPU
2412 pernode one pool for each NUMA node (equivalent
2413 to global on non-NUMA machines)
2414
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002416
Linus Torvalds1da177e2005-04-16 15:20:36 -07002417 switches= [HW,M68k]
2418
2419 sym53c416= [HW,SCSI]
2420 See header of drivers/scsi/sym53c416.c.
2421
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002422 sysrq_always_enabled
2423 [KNL]
2424 Ignore sysrq setting - this boot parameter will
2425 neutralize any effect of /proc/sys/kernel/sysrq.
2426 Useful for debugging.
2427
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428 t128= [HW,SCSI]
2429 See header of drivers/scsi/t128.c.
2430
2431 tdfx= [HW,DRM]
2432
David Brownell77437fd2008-07-23 21:28:33 -07002433 test_suspend= [SUSPEND]
2434 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2435 standby suspend) as the system sleep state to briefly
2436 enter during system startup. The system is woken from
2437 this state using a wakeup-capable RTC alarm.
2438
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439 thash_entries= [KNL,NET]
2440 Set number of hash buckets for TCP connection
2441
Len Brownf8707ec2007-08-12 00:12:54 -04002442 thermal.act= [HW,ACPI]
2443 -1: disable all active trip points in all thermal zones
2444 <degrees C>: override all lowest active trip points
2445
Len Brownc52a7412007-08-14 15:49:32 -04002446 thermal.crt= [HW,ACPI]
2447 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002448 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002449
Len Brownf5487142007-08-12 00:12:44 -04002450 thermal.nocrt= [HW,ACPI]
2451 Set to disable actions on ACPI thermal zone
2452 critical and hot trip points.
2453
Len Brown72b33ef2007-08-12 00:12:17 -04002454 thermal.off= [HW,ACPI]
2455 1: disable ACPI thermal control
2456
Len Browna70cdc52007-08-12 00:12:35 -04002457 thermal.psv= [HW,ACPI]
2458 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002459 <degrees C>: override all passive trip points to this
2460 value
Len Browna70cdc52007-08-12 00:12:35 -04002461
Len Brown730ff342007-08-12 00:12:26 -04002462 thermal.tzp= [HW,ACPI]
2463 Specify global default ACPI thermal zone polling rate
2464 <deci-seconds>: poll all this frequency
2465 0: no polling (default)
2466
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467 tmscsim= [HW,SCSI]
2468 See comment before function dc390_setup() in
2469 drivers/scsi/tmscsim.c.
2470
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002471 topology= [S390]
2472 Format: {off | on}
2473 Specify if the kernel should make use of the cpu
2474 topology informations if the hardware supports these.
2475 The scheduler will make use of these informations and
2476 e.g. base its process migration decisions on it.
2477 Default is off.
2478
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479 tp720= [HW,PS2]
2480
Li Zefan9d612be2009-06-24 17:33:15 +08002481 trace_buf_size=nn[KMG]
2482 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002483
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002485 Format:
2486 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2487
Alok Kataria395628e2008-10-24 17:22:01 -07002488 tsc= Disable clocksource-must-verify flag for TSC.
2489 Format: <string>
2490 [x86] reliable: mark tsc clocksource as reliable, this
2491 disables clocksource verification at runtime.
2492 Used to enable high-resolution timer mode on older
2493 hardware, and in virtualized environment.
2494
Randy Dunlapa9913042005-10-23 12:57:11 -07002495 turbografx.map[2|3]= [HW,JOY]
2496 TurboGraFX parallel port interface
2497 Format:
2498 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002499 See also Documentation/input/joystick-parport.txt
2500
2501 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2502 See header of drivers/scsi/u14-34f.c.
2503
2504 uart401= [HW,OSS]
2505 Format: <io>,<irq>
2506
2507 uart6850= [HW,OSS]
2508 Format: <io>,<irq>
2509
Alan Stern5f8364b2006-12-05 16:29:55 -05002510 uhci-hcd.ignore_oc=
2511 [USB] Ignore overcurrent events (default N).
2512 Some badly-designed motherboards generate lots of
2513 bogus events, for ports that aren't wired to
2514 anything. Set this parameter to avoid log spamming.
2515 Note that genuine overcurrent events won't be
2516 reported either.
2517
Simon Arlotte3a61b02008-07-19 23:32:54 +01002518 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302519 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002520 Set unknown_nmi_panic=1 early on boot.
2521
Alan Sternb5e795f2007-02-20 15:00:53 -05002522 usbcore.autosuspend=
2523 [USB] The autosuspend time delay (in seconds) used
2524 for newly-detected USB devices (default 2). This
2525 is the time required before an idle device will be
2526 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002527 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002528
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002529 usbcore.usbfs_snoop=
2530 [USB] Set to log all usbfs traffic (default 0 = off).
2531
2532 usbcore.blinkenlights=
2533 [USB] Set to cycle leds on hubs (default 0 = off).
2534
2535 usbcore.old_scheme_first=
2536 [USB] Start with the old device initialization
2537 scheme (default 0 = off).
2538
2539 usbcore.use_both_schemes=
2540 [USB] Try the other device initialization scheme
2541 if the first one fails (default 1 = enabled).
2542
2543 usbcore.initial_descriptor_timeout=
2544 [USB] Specifies timeout for the initial 64-byte
2545 USB_REQ_GET_DESCRIPTOR request in milliseconds
2546 (default 5000 = 5.0 seconds).
2547
Linus Torvalds1da177e2005-04-16 15:20:36 -07002548 usbhid.mousepoll=
2549 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002550
Alan Sternd4f373e2008-11-10 14:07:45 -05002551 usb-storage.delay_use=
2552 [UMS] The delay in seconds before a new device is
2553 scanned for Logical Units (default 5).
2554
2555 usb-storage.quirks=
2556 [UMS] A list of quirks entries to supplement or
2557 override the built-in unusual_devs list. List
2558 entries are separated by commas. Each entry has
2559 the form VID:PID:Flags where VID and PID are Vendor
2560 and Product ID values (4-digit hex numbers) and
2561 Flags is a set of characters, each corresponding
2562 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002563 a = SANE_SENSE (collect more than 18 bytes
2564 of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002565 c = FIX_CAPACITY (decrease the reported
2566 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002567 h = CAPACITY_HEURISTICS (decrease the
2568 reported device capacity by one
2569 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002570 i = IGNORE_DEVICE (don't bind to this
2571 device);
2572 l = NOT_LOCKABLE (don't try to lock and
2573 unlock ejectable media);
2574 m = MAX_SECTORS_64 (don't transfer more
2575 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002576 o = CAPACITY_OK (accept the capacity
2577 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002578 r = IGNORE_RESIDUE (the device reports
2579 bogus residue values);
2580 s = SINGLE_LUN (the device has only one
2581 Logical Unit);
2582 w = NO_WP_DETECT (don't test whether the
2583 medium is write-protected).
2584 Example: quirks=0419:aaf5:rl,0421:0433:rc
2585
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302586 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002587 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002588 vdso=1: enable VDSO (default)
2589 vdso=0: disable VDSO mapping
2590
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302591 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002592 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2593 vdso32=1: enable 32-bit VDSO (default)
2594 vdso32=0: disable 32-bit VDSO mapping
2595
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002596 vector= [IA-64,SMP]
2597 vector=percpu: enable percpu vector domain
2598
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 video= [FB] Frame buffer configuration
2600 See Documentation/fb/modedb.txt.
2601
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002602 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002603 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002604 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002605 Use vga=ask for menu.
2606 This is actually a boot loader parameter; the value is
2607 passed to the kernel using a special protocol.
2608
Randy Dunlapa9913042005-10-23 12:57:11 -07002609 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610 size of <nn>. This can be used to increase the
2611 minimum size (128MB on x86). It can also be used to
2612 decrease the size and leave more room for directly
2613 mapped kernel RAM.
2614
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002615 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2616 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002617
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002618 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2619 Format: <command>
2620
2621 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2622 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002623
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002624 vt.default_blu= [VT]
2625 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2626 Change the default blue palette of the console.
2627 This is a 16-member array composed of values
2628 ranging from 0-255.
2629
2630 vt.default_grn= [VT]
2631 Format: <green0>,<green1>,<green2>,...,<green15>
2632 Change the default green palette of the console.
2633 This is a 16-member array composed of values
2634 ranging from 0-255.
2635
2636 vt.default_red= [VT]
2637 Format: <red0>,<red1>,<red2>,...,<red15>
2638 Change the default red palette of the console.
2639 This is a 16-member array composed of values
2640 ranging from 0-255.
2641
2642 vt.default_utf8=
2643 [VT]
2644 Format=<0|1>
2645 Set system-wide default UTF-8 mode for all tty's.
2646 Default is 1, i.e. UTF-8 mode is enabled for all
2647 newly opened terminals.
2648
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649 waveartist= [HW,OSS]
2650 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002651
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652 wd33c93= [HW,SCSI]
2653 See header of drivers/scsi/wd33c93.c.
2654
2655 wd7000= [HW,SCSI]
2656 See header of drivers/scsi/wd7000.c.
2657
2658 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002659 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002660
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002661 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2662 default x2apic cluster mode on platforms
2663 supporting x2apic.
2664
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2666 xd_geo= See header of drivers/block/xd.c.
2667
2668 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002669 Format:
2670 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671
Randy Dunlapa9913042005-10-23 12:57:11 -07002672______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673
2674TODO:
2675
2676 Add documentation for ALSA options.
2677 Add more DRM drivers.