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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
Zhao Yakuif5adfaa2008-08-11 14:57:50 +0800232 acpi.power_nocheck= [HW,ACPI]
233 Format: 1/0 enable/disable the check of power state.
234 On some bogus BIOS the _PSC object/_STA object of
235 power resource can't return the correct device power
236 state. In such case it is unneccessary to check its
237 power state again in power transition.
238 1 : disable the power state check
239
Randy Dunlap4af94f32009-04-17 18:30:28 -0700240 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
241 Format: { level | edge | high | low }
242
243 acpi_serialize [HW,ACPI] force serialization of AML methods
244
245 acpi_skip_timer_override [HW,ACPI]
246 Recognize and ignore IRQ0/pin2 Interrupt Override.
247 For broken nForce2 BIOS resulting in XT-PIC timer.
248
249 acpi_sleep= [HW,ACPI] Sleep options
250 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
251 old_ordering, s4_nonvs }
252 See Documentation/power/video.txt for information on
253 s3_bios and s3_mode.
254 s3_beep is for debugging; it makes the PC's speaker beep
255 as soon as the kernel's real-mode entry point is called.
256 s4_nohwsig prevents ACPI hardware signature from being
257 used during resume from hibernation.
258 old_ordering causes the ACPI 1.0 ordering of the _PTS
259 control method, with respect to putting devices into
260 low power states, to be enforced (the ACPI 2.0 ordering
261 of _PTS is used by default).
262 s4_nonvs prevents the kernel from saving/restoring the
263 ACPI NVS memory during hibernation.
264
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
268
Luca Tettamanti7e905602009-03-30 00:01:27 +0200269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
284
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 ad1848= [HW,OSS]
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
287
Randy Dunlap4af94f32009-04-17 18:30:28 -0700288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 advansys= [HW,SCSI]
292 See header of drivers/scsi/advansys.c.
293
294 advwdt= [HW,WDT] Advantech WDT
295 Format: <iostart>,<iostop>
296
297 aedsp16= [HW,OSS] Audio Excel DSP 16
298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
299 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700300
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700301 agp= [AGP]
302 { off | try_unsupported }
303 off: disable AGP support
304 try_unsupported: try to drive unsupported chipsets
305 (may crash computer or cause data corruption)
306
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 aha152x= [HW,SCSI]
308 See Documentation/scsi/aha152x.txt.
309
310 aha1542= [HW,SCSI]
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
312
313 aic7xxx= [HW,SCSI]
314 See Documentation/scsi/aic7xxx.txt.
315
316 aic79xx= [HW,SCSI]
317 See Documentation/scsi/aic79xx.txt.
318
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
321 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200322 isolate - enable device isolation (each device, as far
323 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100324 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100325 share - put every device behind one IOMMU into the
326 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900327 fullflush - enable flushing of IO/TLB entries when
328 they are unmapped. Otherwise they are
329 flushed before they will be reused, which
330 is a lot of faster
331
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 amijoy.map= [HW,JOY] Amiga joystick support
333 Map of devices attached to JOY0DAT and JOY1DAT
334 Format: <a>,<b>
335 See also Documentation/kernel/input/joystick.txt
336
337 analog.map= [HW,JOY] Analog joystick and gamepad support
338 Specifies type or capabilities of an analog joystick
339 connected to one of 16 gameports
340 Format: <type1>,<type2>,..<type16>
341
Randy Dunlapa9913042005-10-23 12:57:11 -0700342 apc= [HW,SPARC]
343 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 Format: noidle
345 Disable APC CPU standby support. SPARCstation-Fox does
346 not play well with APC CPU idle - disable it if you have
347 APC and your system crashes randomly.
348
Randy Dunlapca1eda22009-05-06 16:02:58 -0700349 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700350 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 Format: { quiet (default) | verbose | debug }
352 Change the amount of debugging information output
353 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700354
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700356 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
359 Format: <io>,<irq>,<nodeID>
360
361 ataflop= [HW,M68k]
362
363 atarimouse= [HW,MOUSE] Atari Mouse
364
365 atascsi= [HW,SCSI] Atari SCSI
366
367 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
368 EzKey and similar keyboards
369
370 atkbd.reset= [HW] Reset keyboard during initialization
371
Randy Dunlapa9913042005-10-23 12:57:11 -0700372 atkbd.set= [HW] Select keyboard code set
373 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
375 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
376 keyboards
377
378 atkbd.softraw= [HW] Choose between synthetic and real raw mode
379 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700380
381 atkbd.softrepeat= [HW]
382 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
384 autotest [IA64]
385
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 baycom_epp= [HW,AX25]
387 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
390 Format: <io>,<mode>
391 See header of drivers/net/hamradio/baycom_par.c.
392
Randy Dunlapa9913042005-10-23 12:57:11 -0700393 baycom_ser_fdx= [HW,AX25]
394 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 Format: <io>,<irq>,<mode>[,<baud>]
396 See header of drivers/net/hamradio/baycom_ser_fdx.c.
397
Randy Dunlapa9913042005-10-23 12:57:11 -0700398 baycom_ser_hdx= [HW,AX25]
399 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 Format: <io>,<irq>,<mode>
401 See header of drivers/net/hamradio/baycom_ser_hdx.c.
402
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700403 boot_delay= Milliseconds to delay each printk during boot.
404 Values larger than 10 seconds (10000) are changed to
405 no delay (0).
406 Format: integer
407
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700408 bootmem_debug [KNL] Enable bootmem allocator debug messages.
409
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700411 bttv.radio= Most important insmod options are available as
412 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
414 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
415
416 BusLogic= [HW,SCSI]
417 See drivers/scsi/BusLogic.c, comment before function
418 BusLogic_ParseDriverOptions().
419
420 c101= [NET] Moxa C101 synchronous serial card
421
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700422 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 Sometimes CPU hardware bugs make them report the cache
424 size incorrectly. The kernel will attempt work arounds
425 to fix known problems, but for some CPUs it is not
426 possible to determine what the correct size should be.
427 This option provides an override for these situations.
428
James Morris20510f22007-10-16 23:31:32 -0700429 capability.disable=
430 [SECURITY] Disable capabilities. This would normally
431 be used only if an alternative security model is to be
432 configured. Potentially dangerous and should only be
433 used if you are entirely sure of the consequences.
434
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100435 ccw_timeout_log [S390]
436 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437
Paul Menage8bab8dd2008-04-04 14:29:57 -0700438 cgroup_disable= [KNL] Disable a particular controller
439 Format: {name of the controller(s) to disable}
440 {Currently supported controllers - "memory"}
441
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 checkreqprot [SELINUX] Set initial checkreqprot flag value.
443 Format: { "0" | "1" }
444 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700445 0 -- check protection applied by kernel (includes
446 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 1 -- check protection requested by application.
448 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700449 Value can be changed at runtime via
450 /selinux/checkreqprot.
451
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100452 cio_ignore= [S390]
453 See Documentation/s390/CommonIO for details.
454
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700455 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700456 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200457 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700458 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200459 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 Format: { pit | tsc | cyclone | pmtmr }
461
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700462 clocksource= [GENERIC_TIME] Override the default clocksource
463 Format: <string>
464 Override the default clocksource and use the clocksource
465 with the name specified.
466 Some clocksource names to choose from, depending on
467 the platform:
468 [all] jiffies (this is the base, fallback clocksource)
469 [ACPI] acpi_pm
470 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
471 pxa_timer,timer3,32k_counter,timer0_1
472 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700473 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700474 scx200_hrt on Geode; cyclone on IBM x440
475 [MIPS] MIPS
476 [PARISC] cr16
477 [S390] tod
478 [SH] SuperH
479 [SPARC64] tick
480 [X86-64] hpet,tsc
481
Andi Kleenac72e782008-01-30 13:33:21 +0100482 clearcpuid=BITNUM [X86]
483 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800484 arch/x86/include/asm/cpufeature.h for the valid bit
485 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100486 stable over kernel options, but the vendor specific
487 ones should be.
488 Also note that user programs calling CPUID directly
489 or using the feature without checking anything
490 will still see it. This just prevents it from
491 being used by the kernel or shown in /proc/cpuinfo.
492 Also note the kernel might malfunction if you disable
493 some critical bits.
494
Robert Jennings14f966e2009-04-15 05:55:32 +0000495 cmo_free_hint= [PPC] Format: { yes | no }
496 Specify whether pages are marked as being inactive
497 when they are freed. This is used in CMO environments
498 to determine OS memory pressure for page stealing by
499 a hypervisor.
500 Default: yes
501
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530502 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100503 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100504 Range: 0 - 8192
505 Default: 64
506
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700508 Format:
509 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
511 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
512 Format: <io>[,<irq>]
513
Randy Dunlapa9913042005-10-23 12:57:11 -0700514 com90xx= [HW,NET]
515 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 Format: <io>[,<irq>[,<memstart>]]
517
518 condev= [HW,S390] console device
519 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700520
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 console= [KNL] Output console device and options.
522
523 tty<n> Use the virtual console device <n>.
524
525 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800526 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800528 the form "bbbbpnf", where "bbbb" is the baud rate,
529 "p" is parity ("n", "o", or "e"), "n" is number of
530 bits, and "f" is flow control ("r" for RTS or
531 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800533 See Documentation/serial-console.txt for more
534 information. See
535 Documentation/networking/netconsole.txt for an
536 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700538 uart[8250],io,<addr>[,options]
539 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 Start an early, polled-mode console on the 8250/16550
541 UART at the specified I/O port or MMIO address,
542 switching to the matching ttyS device later. The
543 options are the same as for ttyS, above.
544
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700545 If the device connected to the port is not a TTY but a braille
546 device, prepend "brl," before the device type, for instance
547 console=brl,ttyS0
548 For now, only VisioBraille is supported.
549
Daniel Mackf324edc2009-06-16 15:33:52 -0700550 consoleblank= [KNL] The console blank (screen saver) timeout in
551 seconds. Defaults to 10*60 = 10mins. A value of 0
552 disables the blank timer.
553
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800554 coredump_filter=
555 [KNL] Change the default value for
556 /proc/<pid>/coredump_filter.
557 See also Documentation/filesystems/proc.txt.
558
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700560 Format:
561 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700563 crashkernel=nn[KMG]@ss[KMG]
564 [KNL] Reserve a chunk of physical memory to
565 hold a kernel to switch to with kexec on panic.
566
Bernhard Wallefb391592007-10-18 23:41:02 -0700567 crashkernel=range1:size1[,range2:size2,...][@offset]
568 [KNL] Same as above, but depends on the memory
569 in the running system. The syntax of range is
570 start-[end] where start and end are both
571 a memory unit (amount[KMG]). See also
572 Documentation/kdump/kdump.txt for a example.
573
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 cs89x0_dma= [HW,NET]
575 Format: <dma>
576
577 cs89x0_media= [HW,NET]
578 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700579
Randy Dunlapa9913042005-10-23 12:57:11 -0700580 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 See header of drivers/s390/block/dasd_devmap.c.
582
583 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
584 (one device per port)
585 Format: <port#>,<type>
586 See also Documentation/input/joystick-parport.txt
587
588 debug [KNL] Enable kernel debugging (events log level).
589
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700590 debug_locks_verbose=
591 [KNL] verbose self-tests
592 Format=<0|1>
593 Print debugging info while doing the locking API
594 self-tests.
595 We default to 0 (no extra messages), setting it to
596 1 will print _a lot_ more information - normally
597 only useful to kernel developers.
598
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700599 debug_objects [KNL] Enable object debugging
600
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500601 no_debug_objects
602 [KNL] Disable object debugging
603
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200604 debugpat [X86] Enable PAT debugging
605
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200606 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 Format: <area>[,<node>]
608 See also Documentation/networking/decnet.txt.
609
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700610 default_hugepagesz=
611 [same as hugepagesz=] The size of the default
612 HugeTLB page size. This is the size represented by
613 the legacy /proc/ hugepages APIs, used for SHM, and
614 default size when mounting hugetlbfs filesystems.
615 Defaults to the default architecture's huge page size
616 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700617
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 dhash_entries= [KNL]
619 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700620
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 digi= [HW,SERIAL]
622 IO parameters + enable/disable command.
623
624 digiepca= [HW,SERIAL]
625 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000626 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
Yinghai Lu95ffa242008-04-29 03:52:33 -0700628 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700629 The kernel tries to adjust MTRR layout from continuous
630 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700631 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700632
Yinghai Lu093af8d2008-01-30 13:33:32 +0100633 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100634 By default the kernel will trim any uncacheable
635 memory out of your available memory pool based on
636 MTRR settings. This parameter disables that behavior,
637 possibly causing your machine to run very slowly.
638
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530639 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700640 Disable PIN 1 of APIC timer
641 Can be useful to work around chipset bugs.
642
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 dmasound= [HW,OSS] Sound subsystem buffers
644
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700645 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
646 this option disables the debugging code at boot.
647
648 dma_debug_entries=<number>
649 This option allows to tune the number of preallocated
650 entries for DMA-API debugging code. One entry is
651 required per DMA-API allocation. Use this if the
652 DMA-API debugging code disables itself because the
653 architectural default is too low.
654
Joerg Roedel1745de52009-05-22 21:49:51 +0200655 dma_debug_driver=<driver_name>
656 With this option the DMA-API debugging driver
657 filter feature can be enabled at boot time. Just
658 pass the driver to filter for as the parameter.
659 The filter can be disabled or changed to another
660 driver later using sysfs.
661
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 dscc4.setup= [NET]
663
664 dtc3181e= [HW,SCSI]
665
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700666 dynamic_printk Enables pr_debug()/dev_dbg() calls if
667 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
668 These can also be switched on/off via
669 <debugfs>/dynamic_printk/modules
670
671 earlycon= [KNL] Output early console device and options.
672 uart[8250],io,<addr>[,options]
673 uart[8250],mmio,<addr>[,options]
674 Start an early, polled-mode console on the 8250/16550
675 UART at the specified I/O port or MMIO address.
676 The options are the same as for ttyS, above.
677
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530678 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 earlyprintk=vga
680 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700681 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Randy Dunlapa9913042005-10-23 12:57:11 -0700683 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 takes over.
685
Yinghai Lu5c059172008-07-24 17:29:40 -0700686 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
688 Currently only ttyS0 and ttyS1 are supported.
689
690 Interaction with the standard serial driver is not
691 very good.
692
693 The VGA output is eventually overwritten by the real
694 console.
695
696 eata= [HW,SCSI]
697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700699 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 eisa_irq_edge= [PARISC,HW]
702 See header of drivers/parisc/eisa.c.
703
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700704 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700706 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707
708 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800709 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700710 See Documentation/block/as-iosched.txt and
711 Documentation/block/deadline-iosched.txt for details.
712
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530713 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700714 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800715 image elf header. Generally kexec loader will
716 pass this option to capture kernel.
717 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700719 enable_mtrr_cleanup [X86]
720 The kernel tries to adjust MTRR layout from continuous
721 to discrete, to make X server driver able to add WB
722 entry later. This parameter enables that.
723
Randy Dunlapca1eda22009-05-06 16:02:58 -0700724 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700725 Enable PIN 1 of APIC timer
726 Can be useful to work around chipset bugs
727 (in particular on some ATI chipsets).
728 The kernel tries to set a reasonable default.
729
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 enforcing [SELINUX] Set initial enforcing status.
731 Format: {"0" | "1"}
732 See security/selinux/Kconfig help text.
733 0 -- permissive (log only, no denials).
734 1 -- enforcing (deny and log).
735 Default value is 0.
736 Value can be changed at runtime via /selinux/enforce.
737
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 ether= [HW,NET] Ethernet cards parameters
739 This option is obsoleted by the "netdev=" option, which
740 has equivalent usage. See its documentation for details.
741
742 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
743 Format: <io>[,<irq>]
744
Akinobu Mitade1ba092006-12-08 02:39:42 -0800745 failslab=
746 fail_page_alloc=
747 fail_make_request=[KNL]
748 General fault injection mechanism.
749 Format: <interval>,<probability>,<space>,<times>
750 See also /Documentation/fault-injection/.
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 fd_mcs= [HW,SCSI]
753 See header of drivers/scsi/fd_mcs.c.
754
755 fdomain= [HW,SCSI]
756 See header of drivers/scsi/fdomain.c.
757
758 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000759 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760
Alex Chiangf13ae302008-05-08 14:03:23 -0600761 force_pal_cache_flush
762 [IA-64] Avoid check_sal_cache_flush which may hang on
763 buggy SAL_CACHE_FLUSH implementations. Using this
764 parameter will force ia64_sal_cache_flush to call
765 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
766
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100767 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400768 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100769 as early as possible in order to facilitate early
770 boot debugging.
771
772 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400773 [FTRACE] will dump the trace buffers on oops.
774
775 ftrace_filter=[function-list]
776 [FTRACE] Limit the functions traced by the function
777 tracer at boot up. function-list is a comma separated
778 list of functions. This list can be changed at run
779 time by the set_ftrace_filter file in the debugfs
780 tracing directory.
781
782 ftrace_notrace=[function-list]
783 [FTRACE] Do not trace the functions specified in
784 function-list. This list can be changed at run time
785 by the set_ftrace_notrace file in the debugfs
786 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100787
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 gamecon.map[2|3]=
789 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
790 support via parallel port (up to 5 devices per port)
791 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
792 See also Documentation/input/joystick-parport.txt
793
794 gamma= [HW,DRM]
795
Yinghai Luaaf23042008-01-30 13:33:09 +0100796 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
797 Format: off | on
798 default: on
799
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700800 gcov_persist= [GCOV] When non-zero (default), profiling data for
801 kernel modules is saved and remains accessible via
802 debugfs, even when the module is unloaded/reloaded.
803 When zero, profiling data is discarded and associated
804 debugfs files are removed at module unload time.
805
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 gdth= [HW,SCSI]
807 See header of drivers/scsi/gdth.c.
808
809 gpt [EFI] Forces disk with valid GPT signature but
810 invalid Protective MBR to be treated as GPT.
811
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 gvp11= [HW,SCSI]
813
814 hashdist= [KNL,NUMA] Large hashes allocated during boot
815 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700816 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700817 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818
819 hcl= [IA-64] SGI's Hardware Graph compatibility layer
820
821 hd= [EIDE] (E)IDE hard drive subsystem geometry
822 Format: <cyl>,<head>,<sect>
823
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
825 size of <nn>. This works even on boxes that have no
826 highmem otherwise. This also works to reduce highmem
827 size on bigger boxes.
828
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800829 highres= [KNL] Enable/disable high resolution timer mode.
830 Valid parameters: "on", "off"
831 Default: "on"
832
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 hisax= [HW,ISDN]
834 See Documentation/isdn/README.HiSax.
835
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700836 hlt [BUGS=ARM,SH]
837
838 hpet= [X86-32,HPET] option to control HPET usage
839 Format: { enable (default) | disable | force |
840 verbose }
841 disable: disable HPET and use PIT instead
842 force: allow force enabled of undocumented chips (ICH4,
843 VIA, nVidia)
844 verbose: show contents of HPET registers during setup
845
Andi Kleenb4718e62008-07-23 21:27:51 -0700846 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
847 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700848 On x86-64 and powerpc, this option can be specified
849 multiple times interleaved with hugepages= to reserve
850 huge pages of different sizes. Valid pages sizes on
851 x86-64 are 2M (when the CPU supports "pse") and 1G
852 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700853 Note that 1GB pages can only be allocated at boot time
854 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900855
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100856 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
857 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100858 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
859 If specified, z/VM IUCV HVC accepts connections
860 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100861
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700862 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700863 or register an additional I2C bus that is not
864 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700865 Format:
866 <bus_id>,<clkrate>
867
Jiri Kosina36d95732008-10-06 02:51:09 -0400868 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200870 i8042.dumbkbd [HW] Pretend that controller can only read data from
871 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 (Don't attempt to blink the leds)
873 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500874 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400875 i8042.noloop [HW] Disable the AUX Loopback command while probing
876 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 i8042.nomux [HW] Don't check presence of an active multiplexing
878 controller
879 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
880 controllers
881 i8042.panicblink=
882 [HW] Frequency with which keyboard LEDs should blink
883 when kernel panics (default is 0.5 sec)
884 i8042.reset [HW] Reset the controller during init and cleanup
885 i8042.unlock [HW] Unlock (ignore) the keylock
886
887 i810= [HW,DRM]
888
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700889 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
890 indicates that the driver is running on unsupported
891 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
893 does not match list of supported models.
894 i8k.power_status
895 [HW] Report power status in /proc/i8k
896 (disabled by default)
897 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
898 capability is set.
899
900 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
901 See Documentation/mca.txt.
902
903 icn= [HW,ISDN]
904 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
905
David Fries0af80c02009-02-25 20:28:21 +0100906 ide-core.nodma= [HW] (E)IDE subsystem
907 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200908 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
909 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100910 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700912 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
913 Claim all unknown PCI IDE storage controllers.
914
Andi Kleenf039b752007-05-02 19:27:12 +0200915 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800916 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
917 Poll forces a polling idle loop that can slightly
918 improve the performance of waking up a idle CPU, but
919 will use a lot of power and make the system run hot.
920 Not recommended.
921 idle=mwait: On systems which support MONITOR/MWAIT but
922 the kernel chose to not use it because it doesn't save
923 as much power as a normal idle loop, use the
924 MONITOR/MWAIT idle loop anyways. Performance should be
925 the same as idle=poll.
926 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800927 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800928 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700929
Ingo Molnar792908222006-12-06 20:40:51 -0800930 ignore_loglevel [KNL]
931 Ignore loglevel setting - this will print /all/
932 kernel messages to the console. Useful for debugging.
933
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 ihash_entries= [KNL]
935 Set number of hash buckets for inode cache.
936
Mimi Zohar3323eec2009-02-04 09:06:58 -0500937 ima_audit= [IMA]
938 Format: { "0" | "1" }
939 0 -- integrity auditing messages. (Default)
940 1 -- enable informational integrity auditing messages.
941
942 ima_hash= [IMA]
943 Formt: { "sha1" | "md5" }
944 default: "sha1"
945
Eric Paris5789ba32009-05-21 15:47:06 -0400946 ima_tcb [IMA]
947 Load a policy which meets the needs of the Trusted
948 Computing Base. This means IMA will measure all
949 programs exec'd, files mmap'd for exec, and all files
950 opened for read by uid=0.
951
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 in2000= [HW,SCSI]
953 See header of drivers/scsi/in2000.c.
954
955 init= [KNL]
956 Format: <full_path>
957 Run specified binary instead of /sbin/init as init
958 process.
959
960 initcall_debug [KNL] Trace initcalls as they are executed. Useful
961 for working out where the kernel is dying during
962 startup.
963
964 initrd= [BOOT] Specify the location of the initial ramdisk
965
966 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
967 Format: <irq>
968
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700969 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800970 on
971 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700972 off
973 Disable intel iommu driver.
974 igfx_off [Default Off]
975 By default, gfx is mapped as normal device. If a gfx
976 device has a dedicated DMAR unit, the DMAR unit is
977 bypassed by not enabling DMAR with this option. In
978 this case, gfx device will use physical address for
979 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700980 forcedac [x86_64]
981 With this option iommu will not optimize to look
982 for io virtual address below 32 bit forcing dual
983 address cycle on pci bus for cards supporting greater
984 than 32 bit addressing. The default is to look
985 for translation below 32 bit and if not available
986 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800987 strict [Default Off]
988 With this option on every unmap_single operation will
989 result in a hardware IOTLB flush operation as opposed
990 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700991
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700992 inttest= [IA64]
993
994 iomem= Disable strict checking of access to MMIO memory
995 strict regions from userspace.
996 relaxed
997
998 iommu= [x86]
999 off
1000 force
1001 noforce
1002 biomerge
1003 panic
1004 nopanic
1005 merge
1006 nomerge
1007 forcesac
1008 soft
1009
1010 io7= [HW] IO7 for Marvel based alpha systems
1011 See comment before marvel_specify_io7 in
1012 arch/alpha/kernel/core_marvel.c.
1013
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301014 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001015 0x80
1016 Standard port 0x80 based delay
1017 0xed
1018 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001019 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001020 Simple two microseconds delay
1021 none
1022 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001023
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001025 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026
1027 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001028 See comment before ip2_setup() in
1029 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030
1031 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1032 See header of drivers/scsi/ips.c.
1033
Alan Cox200803d2005-06-28 20:45:18 -07001034 irqfixup [HW]
1035 When an interrupt is not handled search all handlers
1036 for it. Intended to get systems with badly broken
1037 firmware running.
1038
1039 irqpoll [HW]
1040 When an interrupt is not handled search all handlers
1041 for it. Also check all handlers each timer
1042 interrupt. Intended to get systems with badly broken
1043 firmware running.
1044
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001046 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047
1048 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001049 Format:
1050 <cpu number>,...,<cpu number>
1051 or
Li Zefanb225d442008-11-06 12:53:39 -08001052 <cpu number>-<cpu number>
1053 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001054 or a mixture
1055 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001056
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 This option can be used to specify one or more CPUs
1058 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001059 algorithms. You can move a process onto or off an
1060 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 <cpu number> begins at 0 and the maximum value is
1062 "number of CPUs in system - 1".
1063
1064 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001065 alternative -- manually setting the CPU mask of all
1066 tasks in the system -- can cause problems and
1067 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068
Randy Dunlapa9913042005-10-23 12:57:11 -07001069 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070
1071 js= [HW,JOY] Analog joystick
1072 See Documentation/input/joystick.txt.
1073
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001074 keepinitrd [HW,ARM]
1075
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301076 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001077 specifies the amount of memory usable by the kernel
1078 for non-movable allocations. The requested amount is
1079 spread evenly throughout all nodes in the system. The
1080 remaining memory in each node is used for Movable
1081 pages. In the event, a node is too small to have both
1082 kernelcore and Movable pages, kernelcore pages will
1083 take priority and other nodes will have a larger number
1084 of kernelcore pages. The Movable zone is used for the
1085 allocation of pages that may be reclaimed or moved
1086 by the page migration subsystem. This means that
1087 HugeTLB pages may not be allocated from this zone.
1088 Note that allocations like PTEs-from-HighMem still
1089 use the HighMem zone if it exists, and the Normal
1090 zone if it does not.
1091
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001092 kgdboc= [HW] kgdb over consoles.
1093 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001094 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001095 Format: <serial_device>[,baud]
1096
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001097 kmac= [MIPS] korina ethernet MAC address.
1098 Configure the RouterBoard 532 series on-chip
1099 Ethernet adapter MAC address.
1100
Catalin Marinas04f70332009-06-11 13:22:39 +01001101 kmemleak= [KNL] Boot-time kmemleak enable/disable
1102 Valid arguments: on, off
1103 Default: on
1104
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301105 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001106 in oops dumps.
1107
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 l2cr= [PPC]
1109
Robert Brosea78bfbf2008-03-29 07:20:23 +11001110 l3cr= [PPC]
1111
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001112 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001113 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301115 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001116 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001117
FD Camifcb71f62008-01-06 19:08:56 +01001118 libata.dma= [LIBATA] DMA control
1119 libata.dma=0 Disable all PATA and SATA DMA
1120 libata.dma=1 PATA and SATA Disk DMA only
1121 libata.dma=2 ATAPI (CDROM) DMA only
1122 libata.dma=4 Compact Flash DMA only
1123 Combinations also work, so libata.dma=3 enables DMA
1124 for disks and CDROMs, but not CFs.
1125
Dave Jones78e70c22007-09-27 11:50:13 -04001126 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1127 when set.
1128 Format: <int>
1129
Tejun Heo33267322008-02-13 09:15:09 +09001130 libata.force= [LIBATA] Force configurations. The format is comma
1131 separated list of "[ID:]VAL" where ID is
1132 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1133 matching port, link or device. Basically, it matches
1134 the ATA ID string printed on console by libata. If
1135 the whole ID part is omitted, the last PORT and DEVICE
1136 values are used. If ID hasn't been specified yet, the
1137 configuration applies to all ports, links and devices.
1138
1139 If only DEVICE is omitted, the parameter applies to
1140 the port and all links and devices behind it. DEVICE
1141 number of 0 either selects the first device or the
1142 first fan-out link behind PMP device. It does not
1143 select the host link. DEVICE number of 15 selects the
1144 host link and device attached to it.
1145
1146 The VAL specifies the configuration to force. As long
1147 as there's no ambiguity shortcut notation is allowed.
1148 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1149 The following configurations can be forced.
1150
1151 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1152 Any ID with matching PORT is used.
1153
1154 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1155
1156 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1157 udma[/][16,25,33,44,66,100,133] notation is also
1158 allowed.
1159
1160 * [no]ncq: Turn on or off NCQ.
1161
Tejun Heo05944bd2008-08-13 20:19:09 +09001162 * nohrst, nosrst, norst: suppress hard, soft
1163 and both resets.
1164
Tejun Heo33267322008-02-13 09:15:09 +09001165 If there are multiple matching configurations changing
1166 the same attribute, the last one is used.
1167
Randy Dunlap7c4be252009-01-06 14:42:44 -08001168 lmb=debug [KNL] Enable lmb debug messages.
1169
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001171 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001173 lockd.nlm_grace_period=P [NFS] Assign grace period.
1174 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001176 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1177 Format: <integer>
1178
1179 lockd.nlm_timeout=T [NFS] Assign timeout value.
1180 Format: <integer>
1181
1182 lockd.nlm_udpport=M [NFS] Assign UDP port.
1183 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
1185 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1186 Format: <irq>
1187
1188 loglevel= All Kernel Messages with a loglevel smaller than the
1189 console loglevel will be printed to the console. It can
1190 also be changed with klogd or other programs. The
1191 loglevels are defined as follows:
1192
1193 0 (KERN_EMERG) system is unusable
1194 1 (KERN_ALERT) action must be taken immediately
1195 2 (KERN_CRIT) critical conditions
1196 3 (KERN_ERR) error conditions
1197 4 (KERN_WARNING) warning conditions
1198 5 (KERN_NOTICE) normal but significant condition
1199 6 (KERN_INFO) informational
1200 7 (KERN_DEBUG) debug-level messages
1201
1202 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001203 Format: { n | nk | nM }
1204 n must be a power of two. The default size
1205 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
Randy Dunlapaccaa242007-10-16 01:29:37 -07001207 logo.nologo [FB] Disables display of the built-in Linux logo.
1208 This may be used to provide more screen space for
1209 kernel log messages and is useful when debugging
1210 kernel boot problems.
1211
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 lp=0 [LP] Specify parallel ports to use, e.g,
1213 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1214 lp=reset first parallel port). 'lp=0' disables the
1215 lp=auto printer driver. 'lp=reset' (which can be
1216 specified in addition to the ports) causes
1217 attached printers to be reset. Using
1218 lp=port1,port2,... specifies the parallel ports
1219 to associate lp devices with, starting with
1220 lp0. A port specification may be 'none' to skip
1221 that lp device, or a parport name such as
1222 'parport0'. Specifying 'lp=auto' instead of a
1223 port specification list means that device IDs
1224 from each port should be examined, to see if
1225 an IEEE 1284-compliant printer is attached; if
1226 so, the driver will manage that printer.
1227 See also header of drivers/char/lp.c.
1228
1229 lpj=n [KNL]
1230 Sets loops_per_jiffy to given constant, thus avoiding
1231 time-consuming boot-time autodetection (up to 250 ms per
1232 CPU). 0 enables autodetection (default). To determine
1233 the correct value for your kernel, boot with normal
1234 autodetection and see what value is printed. Note that
1235 on SMP systems the preset will be applied to all CPUs,
1236 which is likely to cause problems if your CPUs need
1237 significantly divergent settings. An incorrect value
1238 will cause delays in the kernel to be wrong, leading to
1239 unpredictable I/O errors and other breakage. Although
1240 unlikely, in the extreme case this might damage your
1241 hardware.
1242
1243 ltpc= [NET]
1244 Format: <io>,<irq>,<dma>
1245
Randy Dunlapa9913042005-10-23 12:57:11 -07001246 mac5380= [HW,SCSI] Format:
1247 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248
Randy Dunlapa9913042005-10-23 12:57:11 -07001249 machvec= [IA64] Force the use of a particular machine-vector
1250 (machvec) in a generic kernel.
1251 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001253 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1254 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255
1256 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001257 should make use of. maxcpus=n : n >= 0 limits the
1258 kernel to using 'n' processors. n=0 is a special case,
1259 it is equivalent to "nosmp", which also disables
1260 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001262 max_loop= [LOOP] Maximum number of loopback devices that can
1263 be mounted
1264 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001265
Randy Dunlapa9913042005-10-23 12:57:11 -07001266 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267 Should be between 1 and 2^32-1.
1268
1269 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001270 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 Should be between 1 and 16384.
1272
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 mcatest= [IA-64]
1274
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001275 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
Uwe Hermann71cced62008-10-20 09:32:21 -07001277 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001278
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 md= [HW] RAID subsystems devices and level
1280 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001281
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 mdacon= [MDA]
1283 Format: <first>,<last>
1284 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001285
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1287 Amount of memory to be used when the kernel is not able
1288 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001289 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 address space collisions. Without memmap= PCI devices
1291 could be placed at addresses belonging to unused RAM.
1292
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001293 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 memory.
1295
Paul Mundt6902aa82008-09-21 17:14:42 +09001296 memchunk=nn[KMG]
1297 [KNL,SH] Allow user to override the default size for
1298 per-device physically contiguous DMA buffers.
1299
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301300 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 E820 memory map, as specified by the user.
1302 Such memmap=exactmap lines can be constructed based on
1303 BIOS output or other requirements. See the memmap=nn@ss
1304 option description.
1305
1306 memmap=nn[KMG]@ss[KMG]
1307 [KNL] Force usage of a specific region of memory
1308 Region of memory to be used, from ss to ss+nn.
1309
1310 memmap=nn[KMG]#ss[KMG]
1311 [KNL,ACPI] Mark specific memory as ACPI data.
1312 Region of memory to be used, from ss to ss+nn.
1313
1314 memmap=nn[KMG]$ss[KMG]
1315 [KNL,ACPI] Mark specific memory as reserved.
1316 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001317 Example: Exclude memory from 0x18690000-0x1869ffff
1318 memmap=64K$0x18690000
1319 or
1320 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001322 memory_corruption_check=0/1 [X86]
1323 Some BIOSes seem to corrupt the first 64k of
1324 memory when doing things like suspend/resume.
1325 Setting this option will scan the memory
1326 looking for corruption. Enabling this will
1327 both detect corruption and prevent the kernel
1328 from using the memory being corrupted.
1329 However, its intended as a diagnostic tool; if
1330 repeatable BIOS-originated corruption always
1331 affects the same memory, you can use memmap=
1332 to prevent the kernel from using that memory.
1333
1334 memory_corruption_check_size=size [X86]
1335 By default it checks for corruption in the low
1336 64k, making this memory unavailable for normal
1337 use. Use this parameter to scan for
1338 corruption in more or less memory.
1339
1340 memory_corruption_check_period=seconds [X86]
1341 By default it checks for corruption every 60
1342 seconds. Use this parameter to check at some
1343 other rate. 0 disables periodic checking.
1344
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001345 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001346 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001347 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001348 Specifies the number of memtest passes to be
1349 performed. Each pass selects another test
1350 pattern from a given set of patterns. Memtest
1351 fills the memory with this pattern, validates
1352 memory contents and reserves bad memory
1353 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 meye.*= [HW] Set MotionEye Camera parameters
1356 See Documentation/video4linux/meye.txt.
1357
Andres Salomon8f368812007-10-12 23:04:06 +02001358 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1359 Multi-Function General Purpose Timers on AMD Geode
1360 platforms.
1361
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001362 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1363 the BIOS has incorrectly applied a workaround. TinyBIOS
1364 version 0.98 is known to be affected, 0.99 fixes the
1365 problem by letting the user disable the workaround.
1366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 mga= [HW,DRM]
1368
Randy Dunlap1c207f952008-11-19 15:36:16 -08001369 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1370 physical address is ignored.
1371
Mel Gorman6b74ab92008-07-23 21:26:49 -07001372 mminit_loglevel=
1373 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1374 parameter allows control of the logging verbosity for
1375 the additional memory initialisation checks. A value
1376 of 0 disables mminit logging and a level of 4 will
1377 log everything. Information is printed at KERN_DEBUG
1378 so loglevel=8 may also need to be specified.
1379
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 mousedev.tap_time=
1381 [MOUSE] Maximum time between finger touching and
1382 leaving touchpad surface for touch to be considered
1383 a tap and be reported as a left button click (for
1384 touchpads working in absolute mode only).
1385 Format: <msecs>
1386 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1387 reporting absolute coordinates, such as tablets
1388 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1389 reporting absolute coordinates, such as tablets
1390
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301391 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001392 is similar to kernelcore except it specifies the
1393 amount of memory used for migratable allocations.
1394 If both kernelcore and movablecore is specified,
1395 then kernelcore will be at *least* the specified
1396 value but may be more. If movablecore on its own
1397 is specified, the administrator must be careful
1398 that the amount of memory usable for all allocations
1399 is not too small.
1400
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 mpu401= [HW,OSS]
1402 Format: <io>,<irq>
1403
1404 MTD_Partition= [MTD]
1405 Format: <name>,<region-number>,<size>,<offset>
1406
Randy Dunlapa9913042005-10-23 12:57:11 -07001407 MTD_Region= [MTD] Format:
1408 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409
1410 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001411 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412
Ben Dooks9db829f2008-07-03 11:24:29 +01001413 mtdset= [ARM]
1414 ARM/S3C2412 JIVE boot control
1415
1416 See arch/arm/mach-s3c2412/mach-jive.c
1417
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001419 [HW] Make the MicroTouch USB driver use raw coordinates
1420 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001422 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001423 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001424 that could hold holes aka. UC entries.
1425
1426 mtrr_gran_size=nn[KMG] [X86]
1427 Used for mtrr cleanup. It is granularity of mtrr block.
1428 Default is 1.
1429 Large value could prevent small alignment from
1430 using up MTRRs.
1431
1432 mtrr_spare_reg_nr=n [X86]
1433 Format: <integer>
1434 Range: 0,7 : spare reg number
1435 Default : 1
1436 Used for mtrr cleanup. It is spare mtrr entries number.
1437 Set to 2 or more if your graphical card needs more.
1438
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1440
1441 NCR_D700= [HW,SCSI]
1442 See header of drivers/scsi/NCR_D700.c.
1443
1444 ncr5380= [HW,SCSI]
1445
1446 ncr53c400= [HW,SCSI]
1447
1448 ncr53c400a= [HW,SCSI]
1449
1450 ncr53c406a= [HW,SCSI]
1451
1452 ncr53c8xx= [HW,SCSI]
1453
1454 netdev= [NET] Network devices parameters
1455 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1456 Note that mem_start is often overloaded to mean
1457 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001458 This usage is only documented in each driver source
1459 file if at all.
1460
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001461 nf_conntrack.acct=
1462 [NETFILTER] Enable connection tracking flow accounting
1463 0 to disable accounting
1464 1 to enable accounting
1465 Default value depends on CONFIG_NF_CT_ACCT that is
1466 going to be removed in 2.6.29.
1467
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001469 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470
1471 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001472 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473
Trond Myklebusta72b4422006-01-03 09:55:41 +01001474 nfs.callback_tcpport=
1475 [NFS] set the TCP port on which the NFSv4 callback
1476 channel should listen.
1477
Trond Myklebust58df0952006-01-03 09:55:57 +01001478 nfs.idmap_cache_timeout=
1479 [NFS] set the maximum lifetime for idmapper cache
1480 entries.
1481
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001482 nfs.enable_ino64=
1483 [NFS] enable 64-bit inode numbers.
1484 If zero, the NFS client will fake up a 32-bit inode
1485 number for the readdir() and stat() syscalls instead
1486 of returning the full 64-bit number.
1487 The default is to return 64-bit inode numbers.
1488
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001489 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1490 when a NMI is triggered.
1491 Format: [state][,regs][,debounce][,die]
1492
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301493 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001494 Format: [panic,][num]
1495 Valid num: 0,1,2
1496 0 - turn nmi_watchdog off
1497 1 - use the IO-APIC timer for the NMI watchdog
1498 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001499 a performance counter. Note: This will use one
1500 performance counter and the local APIC's performance
1501 vector.
1502 When panic is specified, panic when an NMI watchdog
1503 timeout occurs.
1504 This is useful when you use a panic=... timeout and
1505 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001506 Instead of 1 and 2 it is possible to use the following
1507 symbolic names: lapic and ioapic
1508 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001510 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 emulation library even if a 387 maths coprocessor
1512 is present.
1513
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001514 no_console_suspend
1515 [HW] Never suspend the console
1516 Disable suspending of consoles during suspend and
1517 hibernate operations. Once disabled, debugging
1518 messages can reach various consoles while the rest
1519 of the system is being put to sleep (ie, while
1520 debugging driver suspend/resume hooks). This may
1521 not work reliably with all consoles, but is known
1522 to work with serial and VGA consoles.
1523
Christoph Lameterc1aee212007-05-31 00:40:47 -07001524 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1525 caches in the slab allocator. Saves per-node memory,
1526 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001527
Randy Dunlapa9913042005-10-23 12:57:11 -07001528 noalign [KNL,ARM]
1529
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530 noapic [SMP,APIC] Tells the kernel to not make use of any
1531 IOAPICs that may be present in the system.
1532
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 nobats [PPC] Do not use BATs for mapping kernel lowmem
1534 on "Classic" PPC cores.
1535
1536 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001537
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001538 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1539
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001540 nodelayacct [KNL] Disable per-task delay accounting
1541
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1543
Paul Mundt6902aa82008-09-21 17:14:42 +09001544 nodsp [SH] Disable hardware DSP at boot time.
1545
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301546 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 noexec [IA-64]
1549
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301550 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001551 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001553 noexec=off: disable non-executable mappings
1554
1555 noexec32 [X86-64]
1556 This affects only 32-bit executables.
1557 noexec32=on: enable non-executable mappings (default)
1558 read doesn't imply executable mappings
1559 noexec32=off: disable non-executable mappings
1560 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561
Paul Mundt6902aa82008-09-21 17:14:42 +09001562 nofpu [SH] Disable hardware FPU at boot time.
1563
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001564 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001565 register save and restore. The kernel will only save
1566 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567
Suresh Siddha0c752a92009-05-22 12:17:45 -07001568 noxsave [BUGS=X86] Disables x86 extended register state save
1569 and restore using xsave. The kernel will fallback to
1570 enabling legacy floating-point and sse state.
1571
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001572 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1573 wfi(ARM) instruction doesn't work correctly and not to
1574 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001575
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001576 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 instruction doesn't work correctly and not to
1578 use it.
1579
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001580 no_file_caps Tells the kernel not to honor file capabilities. The
1581 only way then for a file to be executed with privilege
1582 is to be setuid root or executed by root.
1583
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 nohalt [IA-64] Tells the kernel not to use the power saving
1585 function PAL_HALT_LIGHT when idle. This increases
1586 power-consumption. On the positive side, it reduces
1587 interrupt wake-up latency, which may improve performance
1588 in certain environments such as networked servers or
1589 real-time systems.
1590
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001591 nohz= [KNL] Boottime enable/disable dynamic ticks
1592 Valid arguments: on, off
1593 Default: on
1594
Paul Mundteeee7852009-04-02 12:31:16 +09001595 noiotrap [SH] Disables trapped I/O port accesses.
1596
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001597 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598 disable unhandled interrupt sources.
1599
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301600 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001601 broken timer IRQ sources.
1602
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 noisapnp [ISAPNP] Disables ISA PnP code.
1604
1605 noinitrd [RAM] Tells the kernel not to load any configured
1606 initial RAM disk.
1607
Weidong Han03ea8152009-04-17 16:42:15 +08001608 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1609 remapping.
1610
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 nointroute [IA-64]
1612
Tony Luck0aa366f2007-07-20 11:22:30 -07001613 nojitter [IA64] Disables jitter checking for ITC timers.
1614
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001615 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001617 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001618
Linus Torvalds1da177e2005-04-16 15:20:36 -07001619 noltlbs [PPC] Do not use large page/tlb entries for kernel
1620 lowmem mapping on PPC40x.
1621
Horms312f1f02006-02-22 09:57:55 +09001622 nomca [IA-64] Disable machine check abort handling
1623
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001624 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001625
Andres Salomon83d73842007-10-12 23:04:06 +02001626 nomfgpt [X86-32] Disable Multi-Function General Purpose
1627 Timer usage (for AMD Geode machines).
1628
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001629 norandmaps Don't use address space randomization. Equivalent to
1630 echo 0 > /proc/sys/kernel/randomize_va_space
1631
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001632 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001633
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001634 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001635 with UP alternatives
1636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 noresidual [PPC] Don't use residual data on PReP machines.
1638
Randy Dunlapa9913042005-10-23 12:57:11 -07001639 noresume [SWSUSP] Disables resume and restores original swap
1640 space.
1641
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 no-scroll [VGA] Disables scrollback.
1643 This is required for the Braillex ib80-piezo Braille
1644 reader made by F.H. Papenmeier (Germany).
1645
1646 nosbagart [IA-64]
1647
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001648 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001649
Len Brown61ec7562007-08-16 03:34:22 -04001650 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1651 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652
Dave Jones97842212007-07-15 23:41:05 -07001653 nosoftlockup [KNL] Disable the soft-lockup detector.
1654
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001655 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001656 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001657
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 nosync [HW,M68K] Disables sync negotiation for all devices.
1659
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001660 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661
1662 nousb [USB] Disable the USB subsystem
1663
1664 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001665
Weidong Han2b2fd872009-04-17 16:42:12 +08001666 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1667
Fenghua Yua6c75b862008-03-14 13:57:08 -07001668 nptcg= [IA64] Override max number of concurrent global TLB
1669 purges which is reported from either PAL_VM_SUMMARY or
1670 SAL PALO.
1671
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001672 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1673
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001674 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1675 one of ['zone', 'node', 'default'] can be specified
1676 This can be set from sysctl after boot.
1677 See Documentation/sysctl/vm.txt for details.
1678
Randy Dunlap7c4be252009-01-06 14:42:44 -08001679 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1680 See Documentation/debugging-via-ohci1394.txt for more
1681 info.
1682
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001683 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1684 Rather than timing out after 20 ms if an EC
1685 command is not properly ACKed, override the length
1686 of the timeout. We have interrupts disabled while
1687 waiting for the ACK, so if this is set too high
1688 interrupts *may* be lost!
1689
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 opl3= [HW,OSS]
1691 Format: <io>
1692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 oprofile.timer= [HW]
1694 Use timer interrupt instead of performance counters
1695
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001696 oprofile.cpu_type= Force an oprofile cpu type
1697 This might be useful if you have an older oprofile
1698 userland or if you want common events.
1699 Format: { archperfmon }
1700 archperfmon: [X86] Force use of architectural
1701 perfmon on Intel CPUs instead of the
1702 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 osst= [HW,SCSI] SCSI Tape Driver
1705 Format: <buffer_size>,<write_threshold>
1706 See also Documentation/scsi/st.txt.
1707
1708 panic= [KNL] Kernel behaviour on panic
1709 Format: <timeout>
1710
1711 parkbd.port= [HW] Parallel port number the keyboard adapter is
1712 connected to, default is 0.
1713 Format: <parport#>
1714 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1715 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001716 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717
Randy Dunlapa9913042005-10-23 12:57:11 -07001718 parport= [HW,PPT] Specify parallel ports. 0 disables.
1719 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1720 Use 'auto' to force the driver to use any
1721 IRQ/DMA settings detected (the default is to
1722 ignore detected IRQ/DMA settings because of
1723 possible conflicts). You can specify the base
1724 address, IRQ, and DMA settings; IRQ and DMA
1725 should be numbers, or 'auto' (for using detected
1726 settings on that particular port), or 'nofifo'
1727 (to avoid using a FIFO even if it is detected).
1728 Parallel ports are assigned in the order they
1729 are specified on the command line, starting
1730 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731
Randy Dunlapa9913042005-10-23 12:57:11 -07001732 parport_init_mode= [HW,PPT]
1733 Configure VIA parallel port to operate in
1734 a specific mode. This is necessary on Pegasos
1735 computer where firmware has no options for setting
1736 up parallel port mode and sets it to spp.
1737 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738 Format: [spp|ps2|epp|ecp|ecpepp]
1739
Randy Dunlapa9913042005-10-23 12:57:11 -07001740 pas2= [HW,OSS] Format:
1741 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1742
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 pas16= [HW,SCSI]
1744 See header of drivers/scsi/pas16.c.
1745
Andrew Mortondd287792006-03-23 03:00:57 -08001746 pause_on_oops=
1747 Halt all CPUs after the first oops has been printed for
1748 the specified number of seconds. This is to be used if
1749 your oopses keep scrolling off the screen.
1750
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 pcbit= [HW,ISDN]
1752
1753 pcd. [PARIDE]
1754 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001755 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756
Randy Dunlapa9913042005-10-23 12:57:11 -07001757 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001758 earlydump [X86] dump PCI config space before the kernel
1759 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001760 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001761 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001762 the hardware directly. Use this if your machine
1763 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001765 hardware access methods are allowed. Use this
1766 if you experience crashes upon bootup and you
1767 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001768 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001769 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001770 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001771 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001772 noaer [PCIE] If the PCIEAER kernel config parameter is
1773 enabled, this kernel boot option can be used to
1774 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001775 nodomains [PCI] Disable support for multiple PCI
1776 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301777 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001778 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001779 nomsi [MSI] If the PCI_MSI kernel config parameter is
1780 enabled, this kernel boot option can be used to
1781 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001782 noioapicquirk [APIC] Disable all boot interrupt quirks.
1783 Safety option to keep boot IRQs enabled. This
1784 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001785 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1786 primary IO-APIC for bridges that cannot disable
1787 boot IRQs. This fixes a source of spurious IRQs
1788 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001789 noioapicreroute [APIC] Disable workaround that uses the
1790 boot IRQ equivalent of an IRQ that connects to
1791 a chipset where boot IRQs cannot be disabled.
1792 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001793 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001794 routing table. These calls are known to be buggy
1795 on several machines and they hang the machine
1796 when used, but on other computers it's the only
1797 way to get the interrupt routing table. Try
1798 this option if the kernel is unable to allocate
1799 IRQs or discover secondary PCI buses on your
1800 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001801 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001802 Use with caution as certain devices share
1803 address decoders between ROMs and other
1804 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001805 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001806 expansion ROMs that do not already have
1807 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001808 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001809 assigned automatically to PCI devices. You can
1810 make the kernel exclude IRQs of your ISA cards
1811 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001812 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001813 of the PIRQ table (normally generated
1814 by the BIOS) if it is outside the
1815 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001816 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001817 useful if the kernel is unable to find your
1818 secondary buses and you want to tell it
1819 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001820 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001821 numbers ourselves, overriding
1822 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001823 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001824 in the BIOS $PIR table. This is needed on
1825 some systems with broken BIOSes, notably
1826 some HP Pavilion N5400 and Omnibook XE3
1827 notebooks. This will have no effect if ACPI
1828 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001829 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001830 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001831 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001832 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001833 routeirq Do IRQ routing for all PCI devices.
1834 This is normally done in pci_enable_device(),
1835 so this option is a temporary workaround
1836 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001837 skip_isa_align [X86] do not align io start addr, so can
1838 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001839 firmware [ARM] Do not re-enumerate the bus but instead
1840 just use the configuration from the
1841 bootloader. This is currently used on
1842 IXP2000 systems where the bus has to be
1843 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001844 noearly [X86] Don't do any early type 1 scanning.
1845 This might help on some broken boards which
1846 machine check when some devices' config space
1847 is read. But various workarounds are disabled
1848 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001849 bfsort Sort PCI devices into breadth-first order.
1850 This sorting is done to get a device
1851 order compatible with older (<= 2.4) kernels.
1852 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001853 cbiosize=nn[KMG] The fixed amount of bus space which is
1854 reserved for the CardBus bridge's IO window.
1855 The default value is 256 bytes.
1856 cbmemsize=nn[KMG] The fixed amount of bus space which is
1857 reserved for the CardBus bridge's memory
1858 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09001859 resource_alignment=
1860 Format:
1861 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1862 Specifies alignment and device to reassign
1863 aligned memory resources.
1864 If <order of align> is not specified,
1865 PAGE_SIZE is used as alignment.
1866 PCI-PCI bridge can be specified, if resource
1867 windows need to be expanded.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001868
Chuck Ebberte5665a42008-09-24 20:40:34 -04001869 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1870 Management.
1871 off Disable ASPM.
1872 force Enable ASPM even on devices that claim not to support it.
1873 WARNING: Forcing ASPM on may cause system lockups.
1874
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 pcmv= [HW,PCMCIA] BadgePAD 4
1876
1877 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001878 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879
1880 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1881 boot time.
1882 Format: { 0 | 1 }
1883 See arch/parisc/kernel/pdc_chassis.c
1884
Tejun Heofa8a7092009-06-22 11:56:24 +09001885 percpu_alloc= [X86] Select which percpu first chunk allocator to use.
1886 Allowed values are one of "lpage", "embed" and "4k".
1887 See comments in arch/x86/kernel/setup_percpu.c for
1888 details on each allocator. This parameter is primarily
1889 for debugging and performance comparison.
1890
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001892 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
1894 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001895 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
1897 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001898 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899
1900 plip= [PPT,NET] Parallel port network link
1901 Format: { parport<nr> | timid | 0 }
1902 See also Documentation/parport.txt.
1903
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001904 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1905 Override pmtimer IOPort with a hex value.
1906 e.g. pmtmr=0x508
1907
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001908 pnp.debug [PNP]
1909 Enable PNP debug messages. This depends on the
1910 CONFIG_PNP_DEBUG_MESSAGES option.
1911
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 pnpacpi= [ACPI]
1913 { off }
1914
1915 pnpbios= [ISAPNP]
1916 { on | off | curr | res | no-curr | no-res }
1917
1918 pnp_reserve_irq=
1919 [ISAPNP] Exclude IRQs for the autoconfiguration
1920
1921 pnp_reserve_dma=
1922 [ISAPNP] Exclude DMAs for the autoconfiguration
1923
1924 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001925 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926
1927 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001928 [ISAPNP] Exclude memory regions for the
1929 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 Ranges are in pairs (memory base and size).
1931
Randy Dunlap4af94f32009-04-17 18:30:28 -07001932 ports= [IP_VS_FTP] IPVS ftp helper module
1933 Default is 21.
1934 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1935 may be specified.
1936 Format: <port>,<port>....
1937
Ingo Molnar45807a12007-07-15 23:40:10 -07001938 print-fatal-signals=
1939 [KNL] debug: print fatal signals
1940 print-fatal-signals=1: print segfault info to
1941 the kernel console.
1942 default: off.
1943
Randy Dunlape84845c2007-07-15 23:40:25 -07001944 printk.time= Show timing data prefixed to each printk message line
1945 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1946
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001947 processor.max_cstate= [HW,ACPI]
1948 Limit processor to maximum C-state
1949 max_cstate=9 overrides any DMI blacklist limit.
1950
1951 processor.nocst [HW,ACPI]
1952 Ignore the _CST method to determine C-states,
1953 instead using the legacy FADT method
1954
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001956 Format: [schedule,]<number>
1957 Param: "schedule" - profile schedule points.
1958 Param: <number> - step/bucket size as a power of 2 for
1959 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001960 Param: "sleep" - profile D-state sleeping (millisecs).
1961 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001962 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1965 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001966 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967
Randy Dunlapa9913042005-10-23 12:57:11 -07001968 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1969 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1971 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001972 psmouse.resetafter= [HW,MOUSE]
1973 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974 (0 = never).
1975 psmouse.resolution=
1976 [HW,MOUSE] Set desired mouse resolution, in dpi.
1977 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001978 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 0 = disabled, 1 = enabled (default).
1980
1981 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001982 Format:
1983 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984
1985 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001986 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987
Kay Sieversdc8c8582007-08-15 12:25:38 +02001988 pty.legacy_count=
1989 [KNL] Number of legacy pty's. Overwrites compiled-in
1990 default number.
1991
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001992 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001993
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994 r128= [HW,DRM]
1995
1996 raid= [HW,RAID]
1997 See Documentation/md.txt.
1998
Randy Dunlapa9913042005-10-23 12:57:11 -07001999 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002000 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002001
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002003 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002005 rcupdate.blimit= [KNL,BOOT]
2006 Set maximum number of finished RCU callbacks to process
2007 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002008
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002009 rcupdate.qhimark= [KNL,BOOT]
2010 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002011 RCU callbacks over which batch limiting is disabled.
2012
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002013 rcupdate.qlowmark= [KNL,BOOT]
2014 Set threshold of queued RCU callbacks below which
2015 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002016
Olof Johanssonffdfc402005-09-06 15:17:19 -07002017 rdinit= [KNL]
2018 Format: <full_path>
2019 Run specified binary instead of /init from the ramdisk,
2020 used for early userspace startup. See initrd.
2021
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002022 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002024 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002025
Paul Jackson46b6d942008-07-04 10:00:09 -07002026 relax_domain_level=
2027 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002028 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002029
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2031
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002032 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07002033 Format: nn[KMG]
2034 Reserves a hole at the top of the kernel virtual
2035 address space.
2036
Vivek Goyal7e962872006-09-27 01:50:44 -07002037 reset_devices [KNL] Force drivers to reset the underlying device
2038 during initialization.
2039
Randy Dunlapa9913042005-10-23 12:57:11 -07002040 resume= [SWSUSP]
2041 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002043 resume_offset= [SWSUSP]
2044 Specify the offset from the beginning of the partition
2045 given by "resume=" at which the swap header is located,
2046 in <PAGE_SIZE> units (needed only for swap files).
2047 See Documentation/power/swsusp-and-swap-files.txt
2048
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002049 retain_initrd [RAM] Keep initrd memory after extraction
2050
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051 rhash_entries= [KNL,NET]
2052 Set number of hash buckets for route cache
2053
2054 riscom8= [HW,SERIAL]
2055 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2056
2057 ro [KNL] Mount root device read-only on boot
2058
2059 root= [KNL] Root filesystem
2060
2061 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2062 mount the root filesystem
2063
2064 rootflags= [KNL] Set root filesystem mount option string
2065
2066 rootfstype= [KNL] Set root filesystem type
2067
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002068 rootwait [KNL] Wait (indefinitely) for root device to show up.
2069 Useful for devices that are detected asynchronously
2070 (e.g. USB and MMC devices).
2071
James Morris20510f22007-10-16 23:31:32 -07002072 root_plug.vendor_id=
2073 [ROOTPLUG] Override the default vendor ID
2074
2075 root_plug.product_id=
2076 [ROOTPLUG] Override the default product ID
2077
2078 root_plug.debug=
2079 [ROOTPLUG] Enable debugging output
2080
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 rw [KNL] Mount root device read-write on boot
2082
2083 S [KNL] Run init in single mode
2084
2085 sa1100ir [NET]
2086 See drivers/net/irda/sa1100_ir.c.
2087
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002089
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2091 Format: <io>[,<timeout>[,<isapnp>]]
2092
2093 scsi_debug_*= [SCSI]
2094 See drivers/scsi/scsi_debug.c.
2095
2096 scsi_default_dev_flags=
2097 [SCSI] SCSI default device flags
2098 Format: <integer>
2099
2100 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2101 Format: <vendor>:<model>:<flags>
2102 (flags are integer value)
2103
Randy Dunlap6af66322007-11-14 16:52:25 -08002104 scsi_logging_level= [SCSI] a bit mask of logging levels
2105 See drivers/scsi/scsi_logging.h for bits. Also
2106 settable via sysctl at dev.scsi.logging_level
2107 (/proc/sys/dev/scsi/logging_level).
2108 There is also a nice 'scsi_logging_level' script in the
2109 S390-tools package, available for download at
2110 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002112 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2113 discovered. async scans them in kernel threads,
2114 allowing boot to proceed. none ignores them, expecting
2115 user space to do the scan.
2116
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002117 security= [SECURITY] Choose a security module to enable at boot.
2118 If this boot parameter is not specified, only the first
2119 security module asking for security registration will be
2120 loaded. An invalid security module name will be treated
2121 as if no module has been chosen.
2122
2123 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124 Format: { "0" | "1" }
2125 See security/selinux/Kconfig help text.
2126 0 -- disable.
2127 1 -- enable.
2128 Default value is set via kernel config option.
2129 If enabled at boot time, /selinux/disable can be used
2130 later to disable prior to initial policy load.
2131
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002132 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134 shapers= [NET]
2135 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002136
Yinghai Lub05f78f2008-08-22 01:32:50 -07002137 show_msr= [x86] show boot-time MSR settings
2138 Format: { <integer> }
2139 Show boot-time (BIOS-initialized) MSR settings.
2140 The parameter means the number of CPUs to show,
2141 for example 1 means boot CPU only.
2142
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143 sim710= [SCSI,HW]
2144 See header of drivers/scsi/sim710.c.
2145
2146 simeth= [IA-64]
2147 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002148
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149 slram= [HW,MTD]
2150
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002151 slub_debug[=options[,slabs]] [MM, SLUB]
2152 Enabling slub_debug allows one to determine the
2153 culprit if slab objects become corrupted. Enabling
2154 slub_debug can create guard zones around objects and
2155 may poison objects when not in use. Also tracks the
2156 last alloc / free. For more information see
2157 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002158
2159 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002160 Determines the maximum allowed order for slabs.
2161 A high setting may cause OOMs due to memory
2162 fragmentation. For more information see
2163 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002164
2165 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002166 The minimum number of objects per slab. SLUB will
2167 increase the slab order up to slub_max_order to
2168 generate a sufficiently large slab able to contain
2169 the number of objects indicated. The higher the number
2170 of objects the smaller the overhead of tracking slabs
2171 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002172 For more information see Documentation/vm/slub.txt.
2173
2174 slub_min_order= [MM, SLUB]
2175 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002176 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002177 For more information see Documentation/vm/slub.txt.
2178
2179 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002180 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002181 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002182 allocs to different slabs. Debug options disable
2183 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002184 For more information see Documentation/vm/slub.txt.
2185
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 smart2= [HW]
2187 Format: <io1>[,<io2>[,...,<io8>]]
2188
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002189 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002190 attempt to substitute SMP alternatives once at boot.
2191
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002192 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2193 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2194 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2195 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2196 smsc-ircc2.ircc_irq= [HW] IRQ line
2197 smsc-ircc2.ircc_dma= [HW] DMA channel
2198 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2199 0: Toshiba Satellite 1800 (GP data pin select)
2200 1: Fast pin select (default)
2201 2: ATC IRMode
2202
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 snd-ad1816a= [HW,ALSA]
2204
2205 snd-ad1848= [HW,ALSA]
2206
2207 snd-ali5451= [HW,ALSA]
2208
2209 snd-als100= [HW,ALSA]
2210
2211 snd-als4000= [HW,ALSA]
2212
2213 snd-azt2320= [HW,ALSA]
2214
2215 snd-cmi8330= [HW,ALSA]
2216
2217 snd-cmipci= [HW,ALSA]
2218
2219 snd-cs4231= [HW,ALSA]
2220
2221 snd-cs4232= [HW,ALSA]
2222
2223 snd-cs4236= [HW,ALSA]
2224
2225 snd-cs4281= [HW,ALSA]
2226
2227 snd-cs46xx= [HW,ALSA]
2228
2229 snd-dt019x= [HW,ALSA]
2230
2231 snd-dummy= [HW,ALSA]
2232
2233 snd-emu10k1= [HW,ALSA]
2234
2235 snd-ens1370= [HW,ALSA]
2236
2237 snd-ens1371= [HW,ALSA]
2238
2239 snd-es968= [HW,ALSA]
2240
2241 snd-es1688= [HW,ALSA]
2242
2243 snd-es18xx= [HW,ALSA]
2244
2245 snd-es1938= [HW,ALSA]
2246
2247 snd-es1968= [HW,ALSA]
2248
2249 snd-fm801= [HW,ALSA]
2250
2251 snd-gusclassic= [HW,ALSA]
2252
2253 snd-gusextreme= [HW,ALSA]
2254
2255 snd-gusmax= [HW,ALSA]
2256
2257 snd-hdsp= [HW,ALSA]
2258
2259 snd-ice1712= [HW,ALSA]
2260
2261 snd-intel8x0= [HW,ALSA]
2262
2263 snd-interwave= [HW,ALSA]
2264
2265 snd-interwave-stb=
2266 [HW,ALSA]
2267
2268 snd-korg1212= [HW,ALSA]
2269
2270 snd-maestro3= [HW,ALSA]
2271
2272 snd-mpu401= [HW,ALSA]
2273
2274 snd-mtpav= [HW,ALSA]
2275
2276 snd-nm256= [HW,ALSA]
2277
2278 snd-opl3sa2= [HW,ALSA]
2279
2280 snd-opti92x-ad1848=
2281 [HW,ALSA]
2282
2283 snd-opti92x-cs4231=
2284 [HW,ALSA]
2285
2286 snd-opti93x= [HW,ALSA]
2287
2288 snd-pmac= [HW,ALSA]
2289
2290 snd-rme32= [HW,ALSA]
2291
2292 snd-rme96= [HW,ALSA]
2293
2294 snd-rme9652= [HW,ALSA]
2295
2296 snd-sb8= [HW,ALSA]
2297
2298 snd-sb16= [HW,ALSA]
2299
2300 snd-sbawe= [HW,ALSA]
2301
2302 snd-serial= [HW,ALSA]
2303
2304 snd-sgalaxy= [HW,ALSA]
2305
2306 snd-sonicvibes= [HW,ALSA]
2307
2308 snd-sun-amd7930=
2309 [HW,ALSA]
2310
2311 snd-sun-cs4231= [HW,ALSA]
2312
2313 snd-trident= [HW,ALSA]
2314
2315 snd-usb-audio= [HW,ALSA,USB]
2316
2317 snd-via82xx= [HW,ALSA]
2318
2319 snd-virmidi= [HW,ALSA]
2320
2321 snd-wavefront= [HW,ALSA]
2322
2323 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002324
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002325 softlockup_panic=
2326 [KNL] Should the soft-lockup detector generate panics.
2327
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2329 See Documentation/sonypi.txt
2330
2331 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002332 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333
2334 spia_io_base= [HW,MTD]
2335 spia_fio_base=
2336 spia_pedr=
2337 spia_peddr=
2338
2339 sscape= [HW,OSS]
2340 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002341
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2343 See Documentation/scsi/st.txt.
2344
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002345 stacktrace [FTRACE]
2346 Enabled the stack tracer on boot up.
2347
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 sti= [PARISC,HW]
2349 Format: <num>
2350 Set the STI (builtin display/keyboard on the HP-PARISC
2351 machines) console (graphic card) which should be used
2352 as the initial boot-console.
2353 See also comment in drivers/video/console/sticore.c.
2354
2355 sti_font= [HW]
2356 See comment in drivers/video/console/sticore.c.
2357
2358 stifb= [HW]
2359 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2360
Greg Banks42a7fc42007-03-06 01:42:23 -08002361 sunrpc.pool_mode=
2362 [NFS]
2363 Control how the NFS server code allocates CPUs to
2364 service thread pools. Depending on how many NICs
2365 you have and where their interrupts are bound, this
2366 option will affect which CPUs will do NFS serving.
2367 Note: this parameter cannot be changed while the
2368 NFS server is running.
2369
2370 auto the server chooses an appropriate mode
2371 automatically using heuristics
2372 global a single global pool contains all CPUs
2373 percpu one pool for each CPU
2374 pernode one pool for each NUMA node (equivalent
2375 to global on non-NUMA machines)
2376
Linus Torvalds1da177e2005-04-16 15:20:36 -07002377 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002378
Linus Torvalds1da177e2005-04-16 15:20:36 -07002379 switches= [HW,M68k]
2380
2381 sym53c416= [HW,SCSI]
2382 See header of drivers/scsi/sym53c416.c.
2383
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002384 sysrq_always_enabled
2385 [KNL]
2386 Ignore sysrq setting - this boot parameter will
2387 neutralize any effect of /proc/sys/kernel/sysrq.
2388 Useful for debugging.
2389
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390 t128= [HW,SCSI]
2391 See header of drivers/scsi/t128.c.
2392
2393 tdfx= [HW,DRM]
2394
David Brownell77437fd2008-07-23 21:28:33 -07002395 test_suspend= [SUSPEND]
2396 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2397 standby suspend) as the system sleep state to briefly
2398 enter during system startup. The system is woken from
2399 this state using a wakeup-capable RTC alarm.
2400
Linus Torvalds1da177e2005-04-16 15:20:36 -07002401 thash_entries= [KNL,NET]
2402 Set number of hash buckets for TCP connection
2403
Len Brownf8707ec2007-08-12 00:12:54 -04002404 thermal.act= [HW,ACPI]
2405 -1: disable all active trip points in all thermal zones
2406 <degrees C>: override all lowest active trip points
2407
Len Brownc52a7412007-08-14 15:49:32 -04002408 thermal.crt= [HW,ACPI]
2409 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002410 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002411
Len Brownf5487142007-08-12 00:12:44 -04002412 thermal.nocrt= [HW,ACPI]
2413 Set to disable actions on ACPI thermal zone
2414 critical and hot trip points.
2415
Len Brown72b33ef2007-08-12 00:12:17 -04002416 thermal.off= [HW,ACPI]
2417 1: disable ACPI thermal control
2418
Len Browna70cdc52007-08-12 00:12:35 -04002419 thermal.psv= [HW,ACPI]
2420 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002421 <degrees C>: override all passive trip points to this
2422 value
Len Browna70cdc52007-08-12 00:12:35 -04002423
Len Brown730ff342007-08-12 00:12:26 -04002424 thermal.tzp= [HW,ACPI]
2425 Specify global default ACPI thermal zone polling rate
2426 <deci-seconds>: poll all this frequency
2427 0: no polling (default)
2428
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429 tmscsim= [HW,SCSI]
2430 See comment before function dc390_setup() in
2431 drivers/scsi/tmscsim.c.
2432
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002433 topology= [S390]
2434 Format: {off | on}
2435 Specify if the kernel should make use of the cpu
2436 topology informations if the hardware supports these.
2437 The scheduler will make use of these informations and
2438 e.g. base its process migration decisions on it.
2439 Default is off.
2440
Linus Torvalds1da177e2005-04-16 15:20:36 -07002441 tp720= [HW,PS2]
2442
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002443 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2444
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002446 Format:
2447 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2448
Alok Kataria395628e2008-10-24 17:22:01 -07002449 tsc= Disable clocksource-must-verify flag for TSC.
2450 Format: <string>
2451 [x86] reliable: mark tsc clocksource as reliable, this
2452 disables clocksource verification at runtime.
2453 Used to enable high-resolution timer mode on older
2454 hardware, and in virtualized environment.
2455
Randy Dunlapa9913042005-10-23 12:57:11 -07002456 turbografx.map[2|3]= [HW,JOY]
2457 TurboGraFX parallel port interface
2458 Format:
2459 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460 See also Documentation/input/joystick-parport.txt
2461
2462 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2463 See header of drivers/scsi/u14-34f.c.
2464
2465 uart401= [HW,OSS]
2466 Format: <io>,<irq>
2467
2468 uart6850= [HW,OSS]
2469 Format: <io>,<irq>
2470
Alan Stern5f8364b2006-12-05 16:29:55 -05002471 uhci-hcd.ignore_oc=
2472 [USB] Ignore overcurrent events (default N).
2473 Some badly-designed motherboards generate lots of
2474 bogus events, for ports that aren't wired to
2475 anything. Set this parameter to avoid log spamming.
2476 Note that genuine overcurrent events won't be
2477 reported either.
2478
Simon Arlotte3a61b02008-07-19 23:32:54 +01002479 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302480 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002481 Set unknown_nmi_panic=1 early on boot.
2482
Alan Sternb5e795f2007-02-20 15:00:53 -05002483 usbcore.autosuspend=
2484 [USB] The autosuspend time delay (in seconds) used
2485 for newly-detected USB devices (default 2). This
2486 is the time required before an idle device will be
2487 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002488 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002489
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002490 usbcore.usbfs_snoop=
2491 [USB] Set to log all usbfs traffic (default 0 = off).
2492
2493 usbcore.blinkenlights=
2494 [USB] Set to cycle leds on hubs (default 0 = off).
2495
2496 usbcore.old_scheme_first=
2497 [USB] Start with the old device initialization
2498 scheme (default 0 = off).
2499
2500 usbcore.use_both_schemes=
2501 [USB] Try the other device initialization scheme
2502 if the first one fails (default 1 = enabled).
2503
2504 usbcore.initial_descriptor_timeout=
2505 [USB] Specifies timeout for the initial 64-byte
2506 USB_REQ_GET_DESCRIPTOR request in milliseconds
2507 (default 5000 = 5.0 seconds).
2508
Linus Torvalds1da177e2005-04-16 15:20:36 -07002509 usbhid.mousepoll=
2510 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002511
Alan Sternd4f373e2008-11-10 14:07:45 -05002512 usb-storage.delay_use=
2513 [UMS] The delay in seconds before a new device is
2514 scanned for Logical Units (default 5).
2515
2516 usb-storage.quirks=
2517 [UMS] A list of quirks entries to supplement or
2518 override the built-in unusual_devs list. List
2519 entries are separated by commas. Each entry has
2520 the form VID:PID:Flags where VID and PID are Vendor
2521 and Product ID values (4-digit hex numbers) and
2522 Flags is a set of characters, each corresponding
2523 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002524 a = SANE_SENSE (collect more than 18 bytes
2525 of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002526 c = FIX_CAPACITY (decrease the reported
2527 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002528 h = CAPACITY_HEURISTICS (decrease the
2529 reported device capacity by one
2530 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002531 i = IGNORE_DEVICE (don't bind to this
2532 device);
2533 l = NOT_LOCKABLE (don't try to lock and
2534 unlock ejectable media);
2535 m = MAX_SECTORS_64 (don't transfer more
2536 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002537 o = CAPACITY_OK (accept the capacity
2538 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002539 r = IGNORE_RESIDUE (the device reports
2540 bogus residue values);
2541 s = SINGLE_LUN (the device has only one
2542 Logical Unit);
2543 w = NO_WP_DETECT (don't test whether the
2544 medium is write-protected).
2545 Example: quirks=0419:aaf5:rl,0421:0433:rc
2546
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302547 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002548 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002549 vdso=1: enable VDSO (default)
2550 vdso=0: disable VDSO mapping
2551
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302552 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002553 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2554 vdso32=1: enable 32-bit VDSO (default)
2555 vdso32=0: disable 32-bit VDSO mapping
2556
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002557 vector= [IA-64,SMP]
2558 vector=percpu: enable percpu vector domain
2559
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560 video= [FB] Frame buffer configuration
2561 See Documentation/fb/modedb.txt.
2562
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002563 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002564 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002565 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002566 Use vga=ask for menu.
2567 This is actually a boot loader parameter; the value is
2568 passed to the kernel using a special protocol.
2569
Randy Dunlapa9913042005-10-23 12:57:11 -07002570 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 size of <nn>. This can be used to increase the
2572 minimum size (128MB on x86). It can also be used to
2573 decrease the size and leave more room for directly
2574 mapped kernel RAM.
2575
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002576 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2577 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002578
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002579 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2580 Format: <command>
2581
2582 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2583 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002584
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002585 vt.default_blu= [VT]
2586 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2587 Change the default blue palette of the console.
2588 This is a 16-member array composed of values
2589 ranging from 0-255.
2590
2591 vt.default_grn= [VT]
2592 Format: <green0>,<green1>,<green2>,...,<green15>
2593 Change the default green palette of the console.
2594 This is a 16-member array composed of values
2595 ranging from 0-255.
2596
2597 vt.default_red= [VT]
2598 Format: <red0>,<red1>,<red2>,...,<red15>
2599 Change the default red palette of the console.
2600 This is a 16-member array composed of values
2601 ranging from 0-255.
2602
2603 vt.default_utf8=
2604 [VT]
2605 Format=<0|1>
2606 Set system-wide default UTF-8 mode for all tty's.
2607 Default is 1, i.e. UTF-8 mode is enabled for all
2608 newly opened terminals.
2609
Linus Torvalds1da177e2005-04-16 15:20:36 -07002610 waveartist= [HW,OSS]
2611 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002612
Linus Torvalds1da177e2005-04-16 15:20:36 -07002613 wd33c93= [HW,SCSI]
2614 See header of drivers/scsi/wd33c93.c.
2615
2616 wd7000= [HW,SCSI]
2617 See header of drivers/scsi/wd7000.c.
2618
2619 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002620 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002622 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2623 default x2apic cluster mode on platforms
2624 supporting x2apic.
2625
Linus Torvalds1da177e2005-04-16 15:20:36 -07002626 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2627 xd_geo= See header of drivers/block/xd.c.
2628
2629 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002630 Format:
2631 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002632
Randy Dunlapa9913042005-10-23 12:57:11 -07002633______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634
2635TODO:
2636
2637 Add documentation for ALSA options.
2638 Add more DRM drivers.