blob: fbcddc5abe25b7b3ed55f3b8a43680d2c38ddfc3 [file] [log] [blame]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080057 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020061 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070062 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070071 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070072 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070075 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070078 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070082 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070093 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090096 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070099 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500101 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500103 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700111 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700114 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500126need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Karsten Weiss55588702007-02-13 13:26:21 +0100128There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700129See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
jens m. noedler9c4751f2006-09-29 02:00:27 -0700137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530144 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800145 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800146 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700151 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800153 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Randy Dunlap53471122008-03-12 18:10:51 -0400155 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Len Browna1fdcc02007-03-11 03:26:14 -0400157 acpi_apic_instance= [ACPI, IOAPIC]
158 Format: <int>
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400161 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400162
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
165 acpi_backlight=video
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
169
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200193
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800197
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
201 See above.
202
Alex Chiang0406ad32010-01-20 00:06:30 -0700203 acpi_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
204 early. Needed on some platforms to properly
205 initialize the EC.
206
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
209 default in APIC mode
210
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
213 default in PIC mode
214
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
217
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
219 use by PCI
220 Format: <irq>,<irq>...
221
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
226
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
231
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530232 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
236
Randy Dunlap4af94f32009-04-17 18:30:28 -0700237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
239
240 acpi_serialize [HW,ACPI] force serialization of AML methods
241
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
245
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800248 old_ordering, s4_nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700249 See Documentation/power/video.txt for information on
250 s3_bios and s3_mode.
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 s4_nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during hibernation.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700264
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
Russell Kingd944d542010-02-20 16:13:29 +0000319 alignment= [KNL,ARM]
320 Allow the default userspace alignment fault handler
321 behaviour to be specified. Bit 0 enables warnings,
322 bit 1 enables fixups, and bit 2 sends a segfault.
323
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200324 amd_iommu= [HW,X86-84]
325 Pass parameters to the AMD IOMMU driver in the system.
326 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200327 isolate - enable device isolation (each device, as far
328 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100329 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100330 share - put every device behind one IOMMU into the
331 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900332 fullflush - enable flushing of IO/TLB entries when
333 they are unmapped. Otherwise they are
334 flushed before they will be reused, which
335 is a lot of faster
336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
339 Format: <a>,<b>
340 See also Documentation/kernel/input/joystick.txt
341
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
346
Randy Dunlapa9913042005-10-23 12:57:11 -0700347 apc= [HW,SPARC]
348 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 Format: noidle
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
353
Randy Dunlapca1eda22009-05-06 16:02:58 -0700354 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700355 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700359
Brian Haleyb0f83b22010-02-04 13:36:50 -0800360 autoconf= [IPV6]
361 See Documentation/networking/ipv6.txt.
362
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400363 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
364 Limit apic dumping. The parameter defines the maximal
365 number of local apics being dumped. Also it is possible
366 to set it to "all" by meaning -- no limit here.
367 Format: { 1 (default) | 2 | ... | all }.
368 The parameter valid if only apic=debug or
369 apic=verbose is specified.
370 Example: apic=debug show_lapic=all
371
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700373 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
376 Format: <io>,<irq>,<nodeID>
377
378 ataflop= [HW,M68k]
379
380 atarimouse= [HW,MOUSE] Atari Mouse
381
382 atascsi= [HW,SCSI] Atari SCSI
383
384 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
385 EzKey and similar keyboards
386
387 atkbd.reset= [HW] Reset keyboard during initialization
388
Randy Dunlapa9913042005-10-23 12:57:11 -0700389 atkbd.set= [HW] Select keyboard code set
390 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391
392 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
393 keyboards
394
395 atkbd.softraw= [HW] Choose between synthetic and real raw mode
396 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700397
398 atkbd.softrepeat= [HW]
399 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400
401 autotest [IA64]
402
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 baycom_epp= [HW,AX25]
404 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
407 Format: <io>,<mode>
408 See header of drivers/net/hamradio/baycom_par.c.
409
Randy Dunlapa9913042005-10-23 12:57:11 -0700410 baycom_ser_fdx= [HW,AX25]
411 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 Format: <io>,<irq>,<mode>[,<baud>]
413 See header of drivers/net/hamradio/baycom_ser_fdx.c.
414
Randy Dunlapa9913042005-10-23 12:57:11 -0700415 baycom_ser_hdx= [HW,AX25]
416 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 Format: <io>,<irq>,<mode>
418 See header of drivers/net/hamradio/baycom_ser_hdx.c.
419
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700420 boot_delay= Milliseconds to delay each printk during boot.
421 Values larger than 10 seconds (10000) are changed to
422 no delay (0).
423 Format: integer
424
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700425 bootmem_debug [KNL] Enable bootmem allocator debug messages.
426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700428 bttv.radio= Most important insmod options are available as
429 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
431 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
432
433 BusLogic= [HW,SCSI]
434 See drivers/scsi/BusLogic.c, comment before function
435 BusLogic_ParseDriverOptions().
436
437 c101= [NET] Moxa C101 synchronous serial card
438
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700439 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 Sometimes CPU hardware bugs make them report the cache
441 size incorrectly. The kernel will attempt work arounds
442 to fix known problems, but for some CPUs it is not
443 possible to determine what the correct size should be.
444 This option provides an override for these situations.
445
James Morris20510f22007-10-16 23:31:32 -0700446 capability.disable=
447 [SECURITY] Disable capabilities. This would normally
448 be used only if an alternative security model is to be
449 configured. Potentially dangerous and should only be
450 used if you are entirely sure of the consequences.
451
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100452 ccw_timeout_log [S390]
453 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454
Paul Menage8bab8dd2008-04-04 14:29:57 -0700455 cgroup_disable= [KNL] Disable a particular controller
456 Format: {name of the controller(s) to disable}
457 {Currently supported controllers - "memory"}
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 checkreqprot [SELINUX] Set initial checkreqprot flag value.
460 Format: { "0" | "1" }
461 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700462 0 -- check protection applied by kernel (includes
463 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 1 -- check protection requested by application.
465 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700466 Value can be changed at runtime via
467 /selinux/checkreqprot.
468
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100469 cio_ignore= [S390]
470 See Documentation/s390/CommonIO for details.
471
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700472 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700473 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200474 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700475 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200476 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 Format: { pit | tsc | cyclone | pmtmr }
478
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700479 clocksource= [GENERIC_TIME] Override the default clocksource
480 Format: <string>
481 Override the default clocksource and use the clocksource
482 with the name specified.
483 Some clocksource names to choose from, depending on
484 the platform:
485 [all] jiffies (this is the base, fallback clocksource)
486 [ACPI] acpi_pm
487 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
488 pxa_timer,timer3,32k_counter,timer0_1
489 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700490 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700491 scx200_hrt on Geode; cyclone on IBM x440
492 [MIPS] MIPS
493 [PARISC] cr16
494 [S390] tod
495 [SH] SuperH
496 [SPARC64] tick
497 [X86-64] hpet,tsc
498
Andi Kleenac72e782008-01-30 13:33:21 +0100499 clearcpuid=BITNUM [X86]
500 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800501 arch/x86/include/asm/cpufeature.h for the valid bit
502 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100503 stable over kernel options, but the vendor specific
504 ones should be.
505 Also note that user programs calling CPUID directly
506 or using the feature without checking anything
507 will still see it. This just prevents it from
508 being used by the kernel or shown in /proc/cpuinfo.
509 Also note the kernel might malfunction if you disable
510 some critical bits.
511
Robert Jennings14f966e2009-04-15 05:55:32 +0000512 cmo_free_hint= [PPC] Format: { yes | no }
513 Specify whether pages are marked as being inactive
514 when they are freed. This is used in CMO environments
515 to determine OS memory pressure for page stealing by
516 a hypervisor.
517 Default: yes
518
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530519 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100520 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100521 Range: 0 - 8192
522 Default: 64
523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700525 Format:
526 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
528 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
529 Format: <io>[,<irq>]
530
Randy Dunlapa9913042005-10-23 12:57:11 -0700531 com90xx= [HW,NET]
532 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 Format: <io>[,<irq>[,<memstart>]]
534
535 condev= [HW,S390] console device
536 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700537
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 console= [KNL] Output console device and options.
539
540 tty<n> Use the virtual console device <n>.
541
542 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800543 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800545 the form "bbbbpnf", where "bbbb" is the baud rate,
546 "p" is parity ("n", "o", or "e"), "n" is number of
547 bits, and "f" is flow control ("r" for RTS or
548 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800550 See Documentation/serial-console.txt for more
551 information. See
552 Documentation/networking/netconsole.txt for an
553 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700555 uart[8250],io,<addr>[,options]
556 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 Start an early, polled-mode console on the 8250/16550
558 UART at the specified I/O port or MMIO address,
559 switching to the matching ttyS device later. The
560 options are the same as for ttyS, above.
561
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700562 If the device connected to the port is not a TTY but a braille
563 device, prepend "brl," before the device type, for instance
564 console=brl,ttyS0
565 For now, only VisioBraille is supported.
566
Daniel Mackf324edc2009-06-16 15:33:52 -0700567 consoleblank= [KNL] The console blank (screen saver) timeout in
568 seconds. Defaults to 10*60 = 10mins. A value of 0
569 disables the blank timer.
570
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800571 coredump_filter=
572 [KNL] Change the default value for
573 /proc/<pid>/coredump_filter.
574 See also Documentation/filesystems/proc.txt.
575
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700577 Format:
578 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700580 crashkernel=nn[KMG]@ss[KMG]
581 [KNL] Reserve a chunk of physical memory to
582 hold a kernel to switch to with kexec on panic.
583
Bernhard Wallefb391592007-10-18 23:41:02 -0700584 crashkernel=range1:size1[,range2:size2,...][@offset]
585 [KNL] Same as above, but depends on the memory
586 in the running system. The syntax of range is
587 start-[end] where start and end are both
588 a memory unit (amount[KMG]). See also
589 Documentation/kdump/kdump.txt for a example.
590
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 cs89x0_dma= [HW,NET]
592 Format: <dma>
593
594 cs89x0_media= [HW,NET]
595 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700596
Randy Dunlapa9913042005-10-23 12:57:11 -0700597 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 See header of drivers/s390/block/dasd_devmap.c.
599
600 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
601 (one device per port)
602 Format: <port#>,<type>
603 See also Documentation/input/joystick-parport.txt
604
605 debug [KNL] Enable kernel debugging (events log level).
606
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700607 debug_locks_verbose=
608 [KNL] verbose self-tests
609 Format=<0|1>
610 Print debugging info while doing the locking API
611 self-tests.
612 We default to 0 (no extra messages), setting it to
613 1 will print _a lot_ more information - normally
614 only useful to kernel developers.
615
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700616 debug_objects [KNL] Enable object debugging
617
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500618 no_debug_objects
619 [KNL] Disable object debugging
620
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200621 debugpat [X86] Enable PAT debugging
622
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200623 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 Format: <area>[,<node>]
625 See also Documentation/networking/decnet.txt.
626
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700627 default_hugepagesz=
628 [same as hugepagesz=] The size of the default
629 HugeTLB page size. This is the size represented by
630 the legacy /proc/ hugepages APIs, used for SHM, and
631 default size when mounting hugetlbfs filesystems.
632 Defaults to the default architecture's huge page size
633 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700634
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 dhash_entries= [KNL]
636 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700637
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 digi= [HW,SERIAL]
639 IO parameters + enable/disable command.
640
641 digiepca= [HW,SERIAL]
642 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000643 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644
Brian Haleyb0f83b22010-02-04 13:36:50 -0800645 disable= [IPV6]
646 See Documentation/networking/ipv6.txt.
647
648 disable_ipv6= [IPV6]
649 See Documentation/networking/ipv6.txt.
650
Yinghai Lu95ffa242008-04-29 03:52:33 -0700651 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700652 The kernel tries to adjust MTRR layout from continuous
653 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700654 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700655
Yinghai Lu093af8d2008-01-30 13:33:32 +0100656 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100657 By default the kernel will trim any uncacheable
658 memory out of your available memory pool based on
659 MTRR settings. This parameter disables that behavior,
660 possibly causing your machine to run very slowly.
661
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530662 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700663 Disable PIN 1 of APIC timer
664 Can be useful to work around chipset bugs.
665
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 dmasound= [HW,OSS] Sound subsystem buffers
667
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700668 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
669 this option disables the debugging code at boot.
670
671 dma_debug_entries=<number>
672 This option allows to tune the number of preallocated
673 entries for DMA-API debugging code. One entry is
674 required per DMA-API allocation. Use this if the
675 DMA-API debugging code disables itself because the
676 architectural default is too low.
677
Joerg Roedel1745de52009-05-22 21:49:51 +0200678 dma_debug_driver=<driver_name>
679 With this option the DMA-API debugging driver
680 filter feature can be enabled at boot time. Just
681 pass the driver to filter for as the parameter.
682 The filter can be disabled or changed to another
683 driver later using sysfs.
684
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 dscc4.setup= [NET]
686
687 dtc3181e= [HW,SCSI]
688
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700689 dynamic_printk Enables pr_debug()/dev_dbg() calls if
690 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
691 These can also be switched on/off via
692 <debugfs>/dynamic_printk/modules
693
694 earlycon= [KNL] Output early console device and options.
695 uart[8250],io,<addr>[,options]
696 uart[8250],mmio,<addr>[,options]
697 Start an early, polled-mode console on the 8250/16550
698 UART at the specified I/O port or MMIO address.
699 The options are the same as for ttyS, above.
700
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530701 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 earlyprintk=vga
703 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500704 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500705 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
Randy Dunlapa9913042005-10-23 12:57:11 -0700707 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 takes over.
709
Yinghai Lu5c059172008-07-24 17:29:40 -0700710 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
712 Currently only ttyS0 and ttyS1 are supported.
713
714 Interaction with the standard serial driver is not
715 very good.
716
717 The VGA output is eventually overwritten by the real
718 console.
719
720 eata= [HW,SCSI]
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700723 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 eisa_irq_edge= [PARISC,HW]
726 See header of drivers/parisc/eisa.c.
727
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700728 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700730 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800733 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700734 See Documentation/block/as-iosched.txt and
735 Documentation/block/deadline-iosched.txt for details.
736
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530737 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700738 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800739 image elf header. Generally kexec loader will
740 pass this option to capture kernel.
741 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700743 enable_mtrr_cleanup [X86]
744 The kernel tries to adjust MTRR layout from continuous
745 to discrete, to make X server driver able to add WB
746 entry later. This parameter enables that.
747
Randy Dunlapca1eda22009-05-06 16:02:58 -0700748 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700749 Enable PIN 1 of APIC timer
750 Can be useful to work around chipset bugs
751 (in particular on some ATI chipsets).
752 The kernel tries to set a reasonable default.
753
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 enforcing [SELINUX] Set initial enforcing status.
755 Format: {"0" | "1"}
756 See security/selinux/Kconfig help text.
757 0 -- permissive (log only, no denials).
758 1 -- enforcing (deny and log).
759 Default value is 0.
760 Value can be changed at runtime via /selinux/enforce.
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 ether= [HW,NET] Ethernet cards parameters
763 This option is obsoleted by the "netdev=" option, which
764 has equivalent usage. See its documentation for details.
765
766 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
767 Format: <io>[,<irq>]
768
Akinobu Mitade1ba092006-12-08 02:39:42 -0800769 failslab=
770 fail_page_alloc=
771 fail_make_request=[KNL]
772 General fault injection mechanism.
773 Format: <interval>,<probability>,<space>,<times>
774 See also /Documentation/fault-injection/.
775
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 fd_mcs= [HW,SCSI]
777 See header of drivers/scsi/fd_mcs.c.
778
779 fdomain= [HW,SCSI]
780 See header of drivers/scsi/fdomain.c.
781
782 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000783 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
Alex Chiangf13ae302008-05-08 14:03:23 -0600785 force_pal_cache_flush
786 [IA-64] Avoid check_sal_cache_flush which may hang on
787 buggy SAL_CACHE_FLUSH implementations. Using this
788 parameter will force ia64_sal_cache_flush to call
789 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
790
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100791 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400792 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100793 as early as possible in order to facilitate early
794 boot debugging.
795
796 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400797 [FTRACE] will dump the trace buffers on oops.
798
799 ftrace_filter=[function-list]
800 [FTRACE] Limit the functions traced by the function
801 tracer at boot up. function-list is a comma separated
802 list of functions. This list can be changed at run
803 time by the set_ftrace_filter file in the debugfs
804 tracing directory.
805
806 ftrace_notrace=[function-list]
807 [FTRACE] Do not trace the functions specified in
808 function-list. This list can be changed at run time
809 by the set_ftrace_notrace file in the debugfs
810 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100811
Stefan Assmann369bc182009-10-12 22:17:21 +0200812 ftrace_graph_filter=[function-list]
813 [FTRACE] Limit the top level callers functions traced
814 by the function graph tracer at boot up.
815 function-list is a comma separated list of functions
816 that can be changed at run time by the
817 set_graph_function file in the debugfs tracing directory.
818
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 gamecon.map[2|3]=
820 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
821 support via parallel port (up to 5 devices per port)
822 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
823 See also Documentation/input/joystick-parport.txt
824
825 gamma= [HW,DRM]
826
Yinghai Luaaf23042008-01-30 13:33:09 +0100827 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
828 Format: off | on
829 default: on
830
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700831 gcov_persist= [GCOV] When non-zero (default), profiling data for
832 kernel modules is saved and remains accessible via
833 debugfs, even when the module is unloaded/reloaded.
834 When zero, profiling data is discarded and associated
835 debugfs files are removed at module unload time.
836
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 gdth= [HW,SCSI]
838 See header of drivers/scsi/gdth.c.
839
840 gpt [EFI] Forces disk with valid GPT signature but
841 invalid Protective MBR to be treated as GPT.
842
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 gvp11= [HW,SCSI]
844
845 hashdist= [KNL,NUMA] Large hashes allocated during boot
846 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700847 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700848 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849
850 hcl= [IA-64] SGI's Hardware Graph compatibility layer
851
852 hd= [EIDE] (E)IDE hard drive subsystem geometry
853 Format: <cyl>,<head>,<sect>
854
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
856 size of <nn>. This works even on boxes that have no
857 highmem otherwise. This also works to reduce highmem
858 size on bigger boxes.
859
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800860 highres= [KNL] Enable/disable high resolution timer mode.
861 Valid parameters: "on", "off"
862 Default: "on"
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 hisax= [HW,ISDN]
865 See Documentation/isdn/README.HiSax.
866
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700867 hlt [BUGS=ARM,SH]
868
869 hpet= [X86-32,HPET] option to control HPET usage
870 Format: { enable (default) | disable | force |
871 verbose }
872 disable: disable HPET and use PIT instead
873 force: allow force enabled of undocumented chips (ICH4,
874 VIA, nVidia)
875 verbose: show contents of HPET registers during setup
876
Andi Kleenb4718e62008-07-23 21:27:51 -0700877 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
878 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700879 On x86-64 and powerpc, this option can be specified
880 multiple times interleaved with hugepages= to reserve
881 huge pages of different sizes. Valid pages sizes on
882 x86-64 are 2M (when the CPU supports "pse") and 1G
883 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700884 Note that 1GB pages can only be allocated at boot time
885 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900886
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100887 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
888 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100889 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
890 If specified, z/VM IUCV HVC accepts connections
891 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100892
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700893 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700894 or register an additional I2C bus that is not
895 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700896 Format:
897 <bus_id>,<clkrate>
898
Jiri Kosina36d95732008-10-06 02:51:09 -0400899 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200901 i8042.dumbkbd [HW] Pretend that controller can only read data from
902 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 (Don't attempt to blink the leds)
904 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500905 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400906 i8042.noloop [HW] Disable the AUX Loopback command while probing
907 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 i8042.nomux [HW] Don't check presence of an active multiplexing
909 controller
910 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
911 controllers
912 i8042.panicblink=
913 [HW] Frequency with which keyboard LEDs should blink
914 when kernel panics (default is 0.5 sec)
915 i8042.reset [HW] Reset the controller during init and cleanup
916 i8042.unlock [HW] Unlock (ignore) the keylock
917
918 i810= [HW,DRM]
919
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700920 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
921 indicates that the driver is running on unsupported
922 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
924 does not match list of supported models.
925 i8k.power_status
926 [HW] Report power status in /proc/i8k
927 (disabled by default)
928 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
929 capability is set.
930
931 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
932 See Documentation/mca.txt.
933
934 icn= [HW,ISDN]
935 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
936
David Fries0af80c02009-02-25 20:28:21 +0100937 ide-core.nodma= [HW] (E)IDE subsystem
938 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200939 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
940 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100941 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700943 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
944 Claim all unknown PCI IDE storage controllers.
945
Andi Kleenf039b752007-05-02 19:27:12 +0200946 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800947 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
948 Poll forces a polling idle loop that can slightly
949 improve the performance of waking up a idle CPU, but
950 will use a lot of power and make the system run hot.
951 Not recommended.
952 idle=mwait: On systems which support MONITOR/MWAIT but
953 the kernel chose to not use it because it doesn't save
954 as much power as a normal idle loop, use the
955 MONITOR/MWAIT idle loop anyways. Performance should be
956 the same as idle=poll.
957 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800958 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800959 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700960
Ingo Molnar792908222006-12-06 20:40:51 -0800961 ignore_loglevel [KNL]
962 Ignore loglevel setting - this will print /all/
963 kernel messages to the console. Useful for debugging.
964
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 ihash_entries= [KNL]
966 Set number of hash buckets for inode cache.
967
Mimi Zohar3323eec92009-02-04 09:06:58 -0500968 ima_audit= [IMA]
969 Format: { "0" | "1" }
970 0 -- integrity auditing messages. (Default)
971 1 -- enable informational integrity auditing messages.
972
973 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700974 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -0500975 default: "sha1"
976
Eric Paris5789ba32009-05-21 15:47:06 -0400977 ima_tcb [IMA]
978 Load a policy which meets the needs of the Trusted
979 Computing Base. This means IMA will measure all
980 programs exec'd, files mmap'd for exec, and all files
981 opened for read by uid=0.
982
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 in2000= [HW,SCSI]
984 See header of drivers/scsi/in2000.c.
985
986 init= [KNL]
987 Format: <full_path>
988 Run specified binary instead of /sbin/init as init
989 process.
990
991 initcall_debug [KNL] Trace initcalls as they are executed. Useful
992 for working out where the kernel is dying during
993 startup.
994
995 initrd= [BOOT] Specify the location of the initial ramdisk
996
997 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
998 Format: <irq>
999
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001000 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001001 on
1002 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001003 off
1004 Disable intel iommu driver.
1005 igfx_off [Default Off]
1006 By default, gfx is mapped as normal device. If a gfx
1007 device has a dedicated DMAR unit, the DMAR unit is
1008 bypassed by not enabling DMAR with this option. In
1009 this case, gfx device will use physical address for
1010 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001011 forcedac [x86_64]
1012 With this option iommu will not optimize to look
1013 for io virtual address below 32 bit forcing dual
1014 address cycle on pci bus for cards supporting greater
1015 than 32 bit addressing. The default is to look
1016 for translation below 32 bit and if not available
1017 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001018 strict [Default Off]
1019 With this option on every unmap_single operation will
1020 result in a hardware IOTLB flush operation as opposed
1021 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001022
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001023 inttest= [IA64]
1024
1025 iomem= Disable strict checking of access to MMIO memory
1026 strict regions from userspace.
1027 relaxed
1028
1029 iommu= [x86]
1030 off
1031 force
1032 noforce
1033 biomerge
1034 panic
1035 nopanic
1036 merge
1037 nomerge
1038 forcesac
1039 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001040 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001041
1042 io7= [HW] IO7 for Marvel based alpha systems
1043 See comment before marvel_specify_io7 in
1044 arch/alpha/kernel/core_marvel.c.
1045
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301046 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001047 0x80
1048 Standard port 0x80 based delay
1049 0xed
1050 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001051 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001052 Simple two microseconds delay
1053 none
1054 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001055
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001057 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058
1059 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001060 See comment before ip2_setup() in
1061 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
1063 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1064 See header of drivers/scsi/ips.c.
1065
Alan Cox200803d2005-06-28 20:45:18 -07001066 irqfixup [HW]
1067 When an interrupt is not handled search all handlers
1068 for it. Intended to get systems with badly broken
1069 firmware running.
1070
1071 irqpoll [HW]
1072 When an interrupt is not handled search all handlers
1073 for it. Also check all handlers each timer
1074 interrupt. Intended to get systems with badly broken
1075 firmware running.
1076
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001078 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079
1080 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001081 Format:
1082 <cpu number>,...,<cpu number>
1083 or
Li Zefanb225d442008-11-06 12:53:39 -08001084 <cpu number>-<cpu number>
1085 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001086 or a mixture
1087 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001088
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 This option can be used to specify one or more CPUs
1090 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001091 algorithms. You can move a process onto or off an
1092 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093 <cpu number> begins at 0 and the maximum value is
1094 "number of CPUs in system - 1".
1095
1096 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001097 alternative -- manually setting the CPU mask of all
1098 tasks in the system -- can cause problems and
1099 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
Randy Dunlapa9913042005-10-23 12:57:11 -07001101 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102
1103 js= [HW,JOY] Analog joystick
1104 See Documentation/input/joystick.txt.
1105
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001106 keepinitrd [HW,ARM]
1107
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301108 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001109 specifies the amount of memory usable by the kernel
1110 for non-movable allocations. The requested amount is
1111 spread evenly throughout all nodes in the system. The
1112 remaining memory in each node is used for Movable
1113 pages. In the event, a node is too small to have both
1114 kernelcore and Movable pages, kernelcore pages will
1115 take priority and other nodes will have a larger number
1116 of kernelcore pages. The Movable zone is used for the
1117 allocation of pages that may be reclaimed or moved
1118 by the page migration subsystem. This means that
1119 HugeTLB pages may not be allocated from this zone.
1120 Note that allocations like PTEs-from-HighMem still
1121 use the HighMem zone if it exists, and the Normal
1122 zone if it does not.
1123
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001124 kgdboc= [HW] kgdb over consoles.
1125 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001126 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001127 Format: <serial_device>[,baud]
1128
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001129 kmac= [MIPS] korina ethernet MAC address.
1130 Configure the RouterBoard 532 series on-chip
1131 Ethernet adapter MAC address.
1132
Catalin Marinas04f70332009-06-11 13:22:39 +01001133 kmemleak= [KNL] Boot-time kmemleak enable/disable
1134 Valid arguments: on, off
1135 Default: on
1136
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301137 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001138 in oops dumps.
1139
Andre Przywarafef07aa2009-07-10 14:20:35 +02001140 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1141 Default is 0 (don't ignore, but inject #GP)
1142
1143 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1144 Default is 1 (enabled)
1145
1146 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1147 Default is 0 (off)
1148
1149 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1150 for all guests.
1151 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1152
1153 kvm-intel.bypass_guest_pf=
1154 [KVM,Intel] Disables bypassing of guest page faults
1155 on Intel chips. Default is 1 (enabled)
1156
1157 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1158 (virtualized MMU) support on capable Intel chips.
1159 Default is 1 (enabled)
1160
1161 kvm-intel.emulate_invalid_guest_state=
1162 [KVM,Intel] Enable emulation of invalid guest states
1163 Default is 0 (disabled)
1164
1165 kvm-intel.flexpriority=
1166 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1167 Default is 1 (enabled)
1168
1169 kvm-intel.unrestricted_guest=
1170 [KVM,Intel] Disable unrestricted guest feature
1171 (virtualized real and unpaged mode) on capable
1172 Intel chips. Default is 1 (enabled)
1173
1174 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1175 feature (tagged TLBs) on capable Intel chips.
1176 Default is 1 (enabled)
1177
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 l2cr= [PPC]
1179
Robert Brosea78bfbf2008-03-29 07:20:23 +11001180 l3cr= [PPC]
1181
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001182 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001183 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301185 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001186 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001187
FD Camifcb71f62008-01-06 19:08:56 +01001188 libata.dma= [LIBATA] DMA control
1189 libata.dma=0 Disable all PATA and SATA DMA
1190 libata.dma=1 PATA and SATA Disk DMA only
1191 libata.dma=2 ATAPI (CDROM) DMA only
1192 libata.dma=4 Compact Flash DMA only
1193 Combinations also work, so libata.dma=3 enables DMA
1194 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001195
1196 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1197 libata.ignore_hpa=0 keep BIOS limits (default)
1198 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001199
Dave Jones78e70c22007-09-27 11:50:13 -04001200 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1201 when set.
1202 Format: <int>
1203
Tejun Heo33267322008-02-13 09:15:09 +09001204 libata.force= [LIBATA] Force configurations. The format is comma
1205 separated list of "[ID:]VAL" where ID is
1206 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1207 matching port, link or device. Basically, it matches
1208 the ATA ID string printed on console by libata. If
1209 the whole ID part is omitted, the last PORT and DEVICE
1210 values are used. If ID hasn't been specified yet, the
1211 configuration applies to all ports, links and devices.
1212
1213 If only DEVICE is omitted, the parameter applies to
1214 the port and all links and devices behind it. DEVICE
1215 number of 0 either selects the first device or the
1216 first fan-out link behind PMP device. It does not
1217 select the host link. DEVICE number of 15 selects the
1218 host link and device attached to it.
1219
1220 The VAL specifies the configuration to force. As long
1221 as there's no ambiguity shortcut notation is allowed.
1222 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1223 The following configurations can be forced.
1224
1225 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1226 Any ID with matching PORT is used.
1227
1228 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1229
1230 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1231 udma[/][16,25,33,44,66,100,133] notation is also
1232 allowed.
1233
1234 * [no]ncq: Turn on or off NCQ.
1235
Tejun Heo05944bd2008-08-13 20:19:09 +09001236 * nohrst, nosrst, norst: suppress hard, soft
1237 and both resets.
1238
Tejun Heo33267322008-02-13 09:15:09 +09001239 If there are multiple matching configurations changing
1240 the same attribute, the last one is used.
1241
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001242 lmb=debug [KNL] Enable lmb debug messages.
1243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001245 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001247 lockd.nlm_grace_period=P [NFS] Assign grace period.
1248 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001250 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1251 Format: <integer>
1252
1253 lockd.nlm_timeout=T [NFS] Assign timeout value.
1254 Format: <integer>
1255
1256 lockd.nlm_udpport=M [NFS] Assign UDP port.
1257 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258
1259 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1260 Format: <irq>
1261
1262 loglevel= All Kernel Messages with a loglevel smaller than the
1263 console loglevel will be printed to the console. It can
1264 also be changed with klogd or other programs. The
1265 loglevels are defined as follows:
1266
1267 0 (KERN_EMERG) system is unusable
1268 1 (KERN_ALERT) action must be taken immediately
1269 2 (KERN_CRIT) critical conditions
1270 3 (KERN_ERR) error conditions
1271 4 (KERN_WARNING) warning conditions
1272 5 (KERN_NOTICE) normal but significant condition
1273 6 (KERN_INFO) informational
1274 7 (KERN_DEBUG) debug-level messages
1275
1276 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001277 Format: { n | nk | nM }
1278 n must be a power of two. The default size
1279 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
Randy Dunlapaccaa242007-10-16 01:29:37 -07001281 logo.nologo [FB] Disables display of the built-in Linux logo.
1282 This may be used to provide more screen space for
1283 kernel log messages and is useful when debugging
1284 kernel boot problems.
1285
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 lp=0 [LP] Specify parallel ports to use, e.g,
1287 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1288 lp=reset first parallel port). 'lp=0' disables the
1289 lp=auto printer driver. 'lp=reset' (which can be
1290 specified in addition to the ports) causes
1291 attached printers to be reset. Using
1292 lp=port1,port2,... specifies the parallel ports
1293 to associate lp devices with, starting with
1294 lp0. A port specification may be 'none' to skip
1295 that lp device, or a parport name such as
1296 'parport0'. Specifying 'lp=auto' instead of a
1297 port specification list means that device IDs
1298 from each port should be examined, to see if
1299 an IEEE 1284-compliant printer is attached; if
1300 so, the driver will manage that printer.
1301 See also header of drivers/char/lp.c.
1302
1303 lpj=n [KNL]
1304 Sets loops_per_jiffy to given constant, thus avoiding
1305 time-consuming boot-time autodetection (up to 250 ms per
1306 CPU). 0 enables autodetection (default). To determine
1307 the correct value for your kernel, boot with normal
1308 autodetection and see what value is printed. Note that
1309 on SMP systems the preset will be applied to all CPUs,
1310 which is likely to cause problems if your CPUs need
1311 significantly divergent settings. An incorrect value
1312 will cause delays in the kernel to be wrong, leading to
1313 unpredictable I/O errors and other breakage. Although
1314 unlikely, in the extreme case this might damage your
1315 hardware.
1316
1317 ltpc= [NET]
1318 Format: <io>,<irq>,<dma>
1319
Randy Dunlapa9913042005-10-23 12:57:11 -07001320 mac5380= [HW,SCSI] Format:
1321 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322
Randy Dunlapa9913042005-10-23 12:57:11 -07001323 machvec= [IA64] Force the use of a particular machine-vector
1324 (machvec) in a generic kernel.
1325 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326
Wu Zhangjin3209e702009-07-02 23:27:12 +08001327 machtype= [Loongson] Share the same kernel image file between different
1328 yeeloong laptop.
1329 Example: machtype=lemote-yeeloong-2f-7inch
1330
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001331 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1332 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333
1334 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001335 should make use of. maxcpus=n : n >= 0 limits the
1336 kernel to using 'n' processors. n=0 is a special case,
1337 it is equivalent to "nosmp", which also disables
1338 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001340 max_loop= [LOOP] Maximum number of loopback devices that can
1341 be mounted
1342 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001343
Randy Dunlapa9913042005-10-23 12:57:11 -07001344 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 Should be between 1 and 2^32-1.
1346
1347 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001348 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 Should be between 1 and 16384.
1350
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 mcatest= [IA-64]
1352
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001353 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354
Uwe Hermann71cced62008-10-20 09:32:21 -07001355 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 md= [HW] RAID subsystems devices and level
1358 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001359
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 mdacon= [MDA]
1361 Format: <first>,<last>
1362 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001363
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1365 Amount of memory to be used when the kernel is not able
1366 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001367 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 address space collisions. Without memmap= PCI devices
1369 could be placed at addresses belonging to unused RAM.
1370
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001371 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 memory.
1373
Paul Mundt6902aa82008-09-21 17:14:42 +09001374 memchunk=nn[KMG]
1375 [KNL,SH] Allow user to override the default size for
1376 per-device physically contiguous DMA buffers.
1377
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301378 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 E820 memory map, as specified by the user.
1380 Such memmap=exactmap lines can be constructed based on
1381 BIOS output or other requirements. See the memmap=nn@ss
1382 option description.
1383
1384 memmap=nn[KMG]@ss[KMG]
1385 [KNL] Force usage of a specific region of memory
1386 Region of memory to be used, from ss to ss+nn.
1387
1388 memmap=nn[KMG]#ss[KMG]
1389 [KNL,ACPI] Mark specific memory as ACPI data.
1390 Region of memory to be used, from ss to ss+nn.
1391
1392 memmap=nn[KMG]$ss[KMG]
1393 [KNL,ACPI] Mark specific memory as reserved.
1394 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001395 Example: Exclude memory from 0x18690000-0x1869ffff
1396 memmap=64K$0x18690000
1397 or
1398 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001400 memory_corruption_check=0/1 [X86]
1401 Some BIOSes seem to corrupt the first 64k of
1402 memory when doing things like suspend/resume.
1403 Setting this option will scan the memory
1404 looking for corruption. Enabling this will
1405 both detect corruption and prevent the kernel
1406 from using the memory being corrupted.
1407 However, its intended as a diagnostic tool; if
1408 repeatable BIOS-originated corruption always
1409 affects the same memory, you can use memmap=
1410 to prevent the kernel from using that memory.
1411
1412 memory_corruption_check_size=size [X86]
1413 By default it checks for corruption in the low
1414 64k, making this memory unavailable for normal
1415 use. Use this parameter to scan for
1416 corruption in more or less memory.
1417
1418 memory_corruption_check_period=seconds [X86]
1419 By default it checks for corruption every 60
1420 seconds. Use this parameter to check at some
1421 other rate. 0 disables periodic checking.
1422
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001423 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001424 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001425 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001426 Specifies the number of memtest passes to be
1427 performed. Each pass selects another test
1428 pattern from a given set of patterns. Memtest
1429 fills the memory with this pattern, validates
1430 memory contents and reserves bad memory
1431 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 meye.*= [HW] Set MotionEye Camera parameters
1434 See Documentation/video4linux/meye.txt.
1435
Andres Salomon8f368812007-10-12 23:04:06 +02001436 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1437 Multi-Function General Purpose Timers on AMD Geode
1438 platforms.
1439
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001440 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1441 the BIOS has incorrectly applied a workaround. TinyBIOS
1442 version 0.98 is known to be affected, 0.99 fixes the
1443 problem by letting the user disable the workaround.
1444
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 mga= [HW,DRM]
1446
Randy Dunlap1c207f92008-11-19 15:36:16 -08001447 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1448 physical address is ignored.
1449
Michel Pollet39f45d72009-05-20 11:10:31 +01001450 mini2440= [ARM,HW,KNL]
1451 Format:[0..2][b][c][t]
1452 Default: "0tb"
1453 MINI2440 configuration specification:
1454 0 - The attached screen is the 3.5" TFT
1455 1 - The attached screen is the 7" TFT
1456 2 - The VGA Shield is attached (1024x768)
1457 Leaving out the screen size parameter will not load
1458 the TFT driver, and the framebuffer will be left
1459 unconfigured.
1460 b - Enable backlight. The TFT backlight pin will be
1461 linked to the kernel VESA blanking code and a GPIO
1462 LED. This parameter is not necessary when using the
1463 VGA shield.
1464 c - Enable the s3c camera interface.
1465 t - Reserved for enabling touchscreen support. The
1466 touchscreen support is not enabled in the mainstream
1467 kernel as of 2.6.30, a preliminary port can be found
1468 in the "bleeding edge" mini2440 support kernel at
1469 http://repo.or.cz/w/linux-2.6/mini2440.git
1470
Mel Gorman6b74ab92008-07-23 21:26:49 -07001471 mminit_loglevel=
1472 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1473 parameter allows control of the logging verbosity for
1474 the additional memory initialisation checks. A value
1475 of 0 disables mminit logging and a level of 4 will
1476 log everything. Information is printed at KERN_DEBUG
1477 so loglevel=8 may also need to be specified.
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 mousedev.tap_time=
1480 [MOUSE] Maximum time between finger touching and
1481 leaving touchpad surface for touch to be considered
1482 a tap and be reported as a left button click (for
1483 touchpads working in absolute mode only).
1484 Format: <msecs>
1485 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1486 reporting absolute coordinates, such as tablets
1487 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1488 reporting absolute coordinates, such as tablets
1489
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301490 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001491 is similar to kernelcore except it specifies the
1492 amount of memory used for migratable allocations.
1493 If both kernelcore and movablecore is specified,
1494 then kernelcore will be at *least* the specified
1495 value but may be more. If movablecore on its own
1496 is specified, the administrator must be careful
1497 that the amount of memory usable for all allocations
1498 is not too small.
1499
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 mpu401= [HW,OSS]
1501 Format: <io>,<irq>
1502
1503 MTD_Partition= [MTD]
1504 Format: <name>,<region-number>,<size>,<offset>
1505
Randy Dunlapa9913042005-10-23 12:57:11 -07001506 MTD_Region= [MTD] Format:
1507 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508
1509 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001510 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001512 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1513
1514 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1515
1516 boundary - index of last SLC block on Flex-OneNAND.
1517 The remaining blocks are configured as MLC blocks.
1518 lock - Configure if Flex-OneNAND boundary should be locked.
1519 Once locked, the boundary cannot be changed.
1520 1 indicates lock status, 0 indicates unlock status.
1521
Ben Dooks9db829f2008-07-03 11:24:29 +01001522 mtdset= [ARM]
1523 ARM/S3C2412 JIVE boot control
1524
1525 See arch/arm/mach-s3c2412/mach-jive.c
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001528 [HW] Make the MicroTouch USB driver use raw coordinates
1529 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001531 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001532 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001533 that could hold holes aka. UC entries.
1534
1535 mtrr_gran_size=nn[KMG] [X86]
1536 Used for mtrr cleanup. It is granularity of mtrr block.
1537 Default is 1.
1538 Large value could prevent small alignment from
1539 using up MTRRs.
1540
1541 mtrr_spare_reg_nr=n [X86]
1542 Format: <integer>
1543 Range: 0,7 : spare reg number
1544 Default : 1
1545 Used for mtrr cleanup. It is spare mtrr entries number.
1546 Set to 2 or more if your graphical card needs more.
1547
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1549
1550 NCR_D700= [HW,SCSI]
1551 See header of drivers/scsi/NCR_D700.c.
1552
1553 ncr5380= [HW,SCSI]
1554
1555 ncr53c400= [HW,SCSI]
1556
1557 ncr53c400a= [HW,SCSI]
1558
1559 ncr53c406a= [HW,SCSI]
1560
1561 ncr53c8xx= [HW,SCSI]
1562
1563 netdev= [NET] Network devices parameters
1564 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1565 Note that mem_start is often overloaded to mean
1566 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001567 This usage is only documented in each driver source
1568 file if at all.
1569
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001570 nf_conntrack.acct=
1571 [NETFILTER] Enable connection tracking flow accounting
1572 0 to disable accounting
1573 1 to enable accounting
1574 Default value depends on CONFIG_NF_CT_ACCT that is
1575 going to be removed in 2.6.29.
1576
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 nfsaddrs= [NFS]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001578 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
1580 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001581 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582
Trond Myklebusta72b4422006-01-03 09:55:41 +01001583 nfs.callback_tcpport=
1584 [NFS] set the TCP port on which the NFSv4 callback
1585 channel should listen.
1586
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001587 nfs.cache_getent=
1588 [NFS] sets the pathname to the program which is used
1589 to update the NFS client cache entries.
1590
1591 nfs.cache_getent_timeout=
1592 [NFS] sets the timeout after which an attempt to
1593 update a cache entry is deemed to have failed.
1594
Trond Myklebust58df0952006-01-03 09:55:57 +01001595 nfs.idmap_cache_timeout=
1596 [NFS] set the maximum lifetime for idmapper cache
1597 entries.
1598
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001599 nfs.enable_ino64=
1600 [NFS] enable 64-bit inode numbers.
1601 If zero, the NFS client will fake up a 32-bit inode
1602 number for the readdir() and stat() syscalls instead
1603 of returning the full 64-bit number.
1604 The default is to return 64-bit inode numbers.
1605
Paul Mundt1e1030d2009-09-01 17:38:32 +09001606 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001607 when a NMI is triggered.
1608 Format: [state][,regs][,debounce][,die]
1609
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301610 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001611 Format: [panic,][num]
1612 Valid num: 0,1,2
1613 0 - turn nmi_watchdog off
1614 1 - use the IO-APIC timer for the NMI watchdog
1615 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001616 a performance counter. Note: This will use one
1617 performance counter and the local APIC's performance
1618 vector.
1619 When panic is specified, panic when an NMI watchdog
1620 timeout occurs.
1621 This is useful when you use a panic=... timeout and
1622 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001623 Instead of 1 and 2 it is possible to use the following
1624 symbolic names: lapic and ioapic
1625 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
Anton Vorontsovbff38772009-07-08 11:10:56 -07001627 netpoll.carrier_timeout=
1628 [NET] Specifies amount of time (in seconds) that
1629 netpoll should wait for a carrier. By default netpoll
1630 waits 4 seconds.
1631
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001632 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 emulation library even if a 387 maths coprocessor
1634 is present.
1635
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001636 no_console_suspend
1637 [HW] Never suspend the console
1638 Disable suspending of consoles during suspend and
1639 hibernate operations. Once disabled, debugging
1640 messages can reach various consoles while the rest
1641 of the system is being put to sleep (ie, while
1642 debugging driver suspend/resume hooks). This may
1643 not work reliably with all consoles, but is known
1644 to work with serial and VGA consoles.
1645
Christoph Lameterc1aee212007-05-31 00:40:47 -07001646 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1647 caches in the slab allocator. Saves per-node memory,
1648 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001649
Randy Dunlapa9913042005-10-23 12:57:11 -07001650 noalign [KNL,ARM]
1651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 noapic [SMP,APIC] Tells the kernel to not make use of any
1653 IOAPICs that may be present in the system.
1654
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 nobats [PPC] Do not use BATs for mapping kernel lowmem
1656 on "Classic" PPC cores.
1657
1658 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001659
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001660 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1661
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001662 nodelayacct [KNL] Disable per-task delay accounting
1663
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1665
Paul Mundt6902aa82008-09-21 17:14:42 +09001666 nodsp [SH] Disable hardware DSP at boot time.
1667
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301668 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001669
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 noexec [IA-64]
1671
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301672 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001673 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001675 noexec=off: disable non-executable mappings
1676
1677 noexec32 [X86-64]
1678 This affects only 32-bit executables.
1679 noexec32=on: enable non-executable mappings (default)
1680 read doesn't imply executable mappings
1681 noexec32=off: disable non-executable mappings
1682 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
Paul Mundt6902aa82008-09-21 17:14:42 +09001684 nofpu [SH] Disable hardware FPU at boot time.
1685
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001686 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001687 register save and restore. The kernel will only save
1688 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689
Suresh Siddha0c752a92009-05-22 12:17:45 -07001690 noxsave [BUGS=X86] Disables x86 extended register state save
1691 and restore using xsave. The kernel will fallback to
1692 enabling legacy floating-point and sse state.
1693
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001694 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1695 wfi(ARM) instruction doesn't work correctly and not to
1696 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001697
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001698 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 instruction doesn't work correctly and not to
1700 use it.
1701
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001702 no_file_caps Tells the kernel not to honor file capabilities. The
1703 only way then for a file to be executed with privilege
1704 is to be setuid root or executed by root.
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 nohalt [IA-64] Tells the kernel not to use the power saving
1707 function PAL_HALT_LIGHT when idle. This increases
1708 power-consumption. On the positive side, it reduces
1709 interrupt wake-up latency, which may improve performance
1710 in certain environments such as networked servers or
1711 real-time systems.
1712
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001713 nohz= [KNL] Boottime enable/disable dynamic ticks
1714 Valid arguments: on, off
1715 Default: on
1716
Paul Mundteeee7852009-04-02 12:31:16 +09001717 noiotrap [SH] Disables trapped I/O port accesses.
1718
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001719 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 disable unhandled interrupt sources.
1721
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301722 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001723 broken timer IRQ sources.
1724
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 noisapnp [ISAPNP] Disables ISA PnP code.
1726
1727 noinitrd [RAM] Tells the kernel not to load any configured
1728 initial RAM disk.
1729
Weidong Han03ea8152009-04-17 16:42:15 +08001730 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1731 remapping.
1732
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 nointroute [IA-64]
1734
Tony Luck0aa366f2007-07-20 11:22:30 -07001735 nojitter [IA64] Disables jitter checking for ITC timers.
1736
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001737 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001739 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 noltlbs [PPC] Do not use large page/tlb entries for kernel
1742 lowmem mapping on PPC40x.
1743
Horms312f1f02006-02-22 09:57:55 +09001744 nomca [IA-64] Disable machine check abort handling
1745
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001746 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001747
Andres Salomon83d73842007-10-12 23:04:06 +02001748 nomfgpt [X86-32] Disable Multi-Function General Purpose
1749 Timer usage (for AMD Geode machines).
1750
Jiri Kosina016ddd92010-01-18 17:05:40 +01001751 nopat [X86] Disable PAT (page attribute table extension of
1752 pagetables) support.
1753
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001754 norandmaps Don't use address space randomization. Equivalent to
1755 echo 0 > /proc/sys/kernel/randomize_va_space
1756
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001757 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001758
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001759 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001760 with UP alternatives
1761
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 noresidual [PPC] Don't use residual data on PReP machines.
1763
Randy Dunlapa9913042005-10-23 12:57:11 -07001764 noresume [SWSUSP] Disables resume and restores original swap
1765 space.
1766
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 no-scroll [VGA] Disables scrollback.
1768 This is required for the Braillex ib80-piezo Braille
1769 reader made by F.H. Papenmeier (Germany).
1770
1771 nosbagart [IA-64]
1772
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001773 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001774
Len Brown61ec7562007-08-16 03:34:22 -04001775 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1776 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777
Dave Jones97842212007-07-15 23:41:05 -07001778 nosoftlockup [KNL] Disable the soft-lockup detector.
1779
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001780 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001781 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001782
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 nosync [HW,M68K] Disables sync negotiation for all devices.
1784
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001785 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786
1787 nousb [USB] Disable the USB subsystem
1788
1789 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001790
Weidong Han2b2fd872009-04-17 16:42:12 +08001791 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1792
Fenghua Yua6c75b862008-03-14 13:57:08 -07001793 nptcg= [IA64] Override max number of concurrent global TLB
1794 purges which is reported from either PAL_VM_SUMMARY or
1795 SAL PALO.
1796
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001797 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1798
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001799 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1800 one of ['zone', 'node', 'default'] can be specified
1801 This can be set from sysctl after boot.
1802 See Documentation/sysctl/vm.txt for details.
1803
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001804 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1805 See Documentation/debugging-via-ohci1394.txt for more
1806 info.
1807
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001808 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1809 Rather than timing out after 20 ms if an EC
1810 command is not properly ACKed, override the length
1811 of the timeout. We have interrupts disabled while
1812 waiting for the ACK, so if this is set too high
1813 interrupts *may* be lost!
1814
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001815 omap_mux= [OMAP] Override bootloader pin multiplexing.
1816 Format: <mux_mode0.mode_name=value>...
1817 For example, to override I2C bus2:
1818 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1819
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820 opl3= [HW,OSS]
1821 Format: <io>
1822
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 oprofile.timer= [HW]
1824 Use timer interrupt instead of performance counters
1825
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001826 oprofile.cpu_type= Force an oprofile cpu type
1827 This might be useful if you have an older oprofile
1828 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001829 Format: { arch_perfmon }
1830 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001831 perfmon on Intel CPUs instead of the
1832 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001833
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834 osst= [HW,SCSI] SCSI Tape Driver
1835 Format: <buffer_size>,<write_threshold>
1836 See also Documentation/scsi/st.txt.
1837
1838 panic= [KNL] Kernel behaviour on panic
1839 Format: <timeout>
1840
1841 parkbd.port= [HW] Parallel port number the keyboard adapter is
1842 connected to, default is 0.
1843 Format: <parport#>
1844 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1845 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001846 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847
Randy Dunlapa9913042005-10-23 12:57:11 -07001848 parport= [HW,PPT] Specify parallel ports. 0 disables.
1849 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1850 Use 'auto' to force the driver to use any
1851 IRQ/DMA settings detected (the default is to
1852 ignore detected IRQ/DMA settings because of
1853 possible conflicts). You can specify the base
1854 address, IRQ, and DMA settings; IRQ and DMA
1855 should be numbers, or 'auto' (for using detected
1856 settings on that particular port), or 'nofifo'
1857 (to avoid using a FIFO even if it is detected).
1858 Parallel ports are assigned in the order they
1859 are specified on the command line, starting
1860 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861
Randy Dunlapa9913042005-10-23 12:57:11 -07001862 parport_init_mode= [HW,PPT]
1863 Configure VIA parallel port to operate in
1864 a specific mode. This is necessary on Pegasos
1865 computer where firmware has no options for setting
1866 up parallel port mode and sets it to spp.
1867 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868 Format: [spp|ps2|epp|ecp|ecpepp]
1869
Randy Dunlapa9913042005-10-23 12:57:11 -07001870 pas2= [HW,OSS] Format:
1871 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1872
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 pas16= [HW,SCSI]
1874 See header of drivers/scsi/pas16.c.
1875
Andrew Mortondd287792006-03-23 03:00:57 -08001876 pause_on_oops=
1877 Halt all CPUs after the first oops has been printed for
1878 the specified number of seconds. This is to be used if
1879 your oopses keep scrolling off the screen.
1880
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881 pcbit= [HW,ISDN]
1882
1883 pcd. [PARIDE]
1884 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001885 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886
Randy Dunlapa9913042005-10-23 12:57:11 -07001887 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001888 earlydump [X86] dump PCI config space before the kernel
1889 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001890 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001891 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001892 the hardware directly. Use this if your machine
1893 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001894 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001895 hardware access methods are allowed. Use this
1896 if you experience crashes upon bootup and you
1897 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001898 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001899 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001900 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001901 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001902 noaer [PCIE] If the PCIEAER kernel config parameter is
1903 enabled, this kernel boot option can be used to
1904 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001905 nodomains [PCI] Disable support for multiple PCI
1906 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301907 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001908 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001909 check_enable_amd_mmconf [X86] check for and enable
1910 properly configured MMIO access to PCI
1911 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001912 nomsi [MSI] If the PCI_MSI kernel config parameter is
1913 enabled, this kernel boot option can be used to
1914 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001915 noioapicquirk [APIC] Disable all boot interrupt quirks.
1916 Safety option to keep boot IRQs enabled. This
1917 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001918 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1919 primary IO-APIC for bridges that cannot disable
1920 boot IRQs. This fixes a source of spurious IRQs
1921 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001922 noioapicreroute [APIC] Disable workaround that uses the
1923 boot IRQ equivalent of an IRQ that connects to
1924 a chipset where boot IRQs cannot be disabled.
1925 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001926 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001927 routing table. These calls are known to be buggy
1928 on several machines and they hang the machine
1929 when used, but on other computers it's the only
1930 way to get the interrupt routing table. Try
1931 this option if the kernel is unable to allocate
1932 IRQs or discover secondary PCI buses on your
1933 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001934 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001935 Use with caution as certain devices share
1936 address decoders between ROMs and other
1937 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001938 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001939 expansion ROMs that do not already have
1940 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001941 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001942 assigned automatically to PCI devices. You can
1943 make the kernel exclude IRQs of your ISA cards
1944 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001945 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001946 of the PIRQ table (normally generated
1947 by the BIOS) if it is outside the
1948 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001949 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001950 useful if the kernel is unable to find your
1951 secondary buses and you want to tell it
1952 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001953 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001954 numbers ourselves, overriding
1955 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001956 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001957 in the BIOS $PIR table. This is needed on
1958 some systems with broken BIOSes, notably
1959 some HP Pavilion N5400 and Omnibook XE3
1960 notebooks. This will have no effect if ACPI
1961 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001962 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001963 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07001964 use_crs [X86] Use PCI host bridge window information
1965 from ACPI. On BIOSes from 2008 or later, this
1966 is enabled by default. If you need to use this,
1967 please report a bug.
1968 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1969 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07001970 routeirq Do IRQ routing for all PCI devices.
1971 This is normally done in pci_enable_device(),
1972 so this option is a temporary workaround
1973 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001974 skip_isa_align [X86] do not align io start addr, so can
1975 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001976 firmware [ARM] Do not re-enumerate the bus but instead
1977 just use the configuration from the
1978 bootloader. This is currently used on
1979 IXP2000 systems where the bus has to be
1980 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001981 noearly [X86] Don't do any early type 1 scanning.
1982 This might help on some broken boards which
1983 machine check when some devices' config space
1984 is read. But various workarounds are disabled
1985 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001986 bfsort Sort PCI devices into breadth-first order.
1987 This sorting is done to get a device
1988 order compatible with older (<= 2.4) kernels.
1989 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001990 cbiosize=nn[KMG] The fixed amount of bus space which is
1991 reserved for the CardBus bridge's IO window.
1992 The default value is 256 bytes.
1993 cbmemsize=nn[KMG] The fixed amount of bus space which is
1994 reserved for the CardBus bridge's memory
1995 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09001996 resource_alignment=
1997 Format:
1998 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1999 Specifies alignment and device to reassign
2000 aligned memory resources.
2001 If <order of align> is not specified,
2002 PAGE_SIZE is used as alignment.
2003 PCI-PCI bridge can be specified, if resource
2004 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002005 ecrc= Enable/disable PCIe ECRC (transaction layer
2006 end-to-end CRC checking).
2007 bios: Use BIOS/firmware settings. This is the
2008 the default.
2009 off: Turn ECRC off
2010 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002011
Chuck Ebberte5665a42008-09-24 20:40:34 -04002012 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2013 Management.
2014 off Disable ASPM.
2015 force Enable ASPM even on devices that claim not to support it.
2016 WARNING: Forcing ASPM on may cause system lockups.
2017
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002018 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2019 off Do not use native PCIe PME signaling.
2020 force Use native PCIe PME signaling even if the BIOS refuses
2021 to allow the kernel to control the relevant PCIe config
2022 registers.
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002023 nomsi Do not use MSI for native PCIe PME signaling (this makes
2024 all PCIe root ports use INTx for everything).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002025
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 pcmv= [HW,PCMCIA] BadgePAD 4
2027
2028 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002029 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030
2031 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2032 boot time.
2033 Format: { 0 | 1 }
2034 See arch/parisc/kernel/pdc_chassis.c
2035
Tejun Heof58dc012009-08-14 15:00:50 +09002036 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002037 Currently supported values are "embed" and "page".
2038 Archs may support subset or none of the selections.
2039 See comments in mm/percpu.c for details on each
2040 allocator. This parameter is primarily for debugging
2041 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002042
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002044 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045
2046 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002047 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048
2049 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002050 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051
2052 plip= [PPT,NET] Parallel port network link
2053 Format: { parport<nr> | timid | 0 }
2054 See also Documentation/parport.txt.
2055
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002056 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2057 Override pmtimer IOPort with a hex value.
2058 e.g. pmtmr=0x508
2059
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002060 pnp.debug [PNP]
2061 Enable PNP debug messages. This depends on the
2062 CONFIG_PNP_DEBUG_MESSAGES option.
2063
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064 pnpacpi= [ACPI]
2065 { off }
2066
2067 pnpbios= [ISAPNP]
2068 { on | off | curr | res | no-curr | no-res }
2069
2070 pnp_reserve_irq=
2071 [ISAPNP] Exclude IRQs for the autoconfiguration
2072
2073 pnp_reserve_dma=
2074 [ISAPNP] Exclude DMAs for the autoconfiguration
2075
2076 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002077 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078
2079 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002080 [ISAPNP] Exclude memory regions for the
2081 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002082 Ranges are in pairs (memory base and size).
2083
Randy Dunlap4af94f32009-04-17 18:30:28 -07002084 ports= [IP_VS_FTP] IPVS ftp helper module
2085 Default is 21.
2086 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2087 may be specified.
2088 Format: <port>,<port>....
2089
Ingo Molnar45807a12007-07-15 23:40:10 -07002090 print-fatal-signals=
2091 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002092
2093 If enabled, warn about various signal handling
2094 related application anomalies: too many signals,
2095 too many POSIX.1 timers, fatal signals causing a
2096 coredump - etc.
2097
2098 If you hit the warning due to signal overflow,
2099 you might want to try "ulimit -i unlimited".
2100
Ingo Molnar45807a12007-07-15 23:40:10 -07002101 default: off.
2102
Randy Dunlape84845c2007-07-15 23:40:25 -07002103 printk.time= Show timing data prefixed to each printk message line
2104 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2105
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002106 processor.max_cstate= [HW,ACPI]
2107 Limit processor to maximum C-state
2108 max_cstate=9 overrides any DMI blacklist limit.
2109
2110 processor.nocst [HW,ACPI]
2111 Ignore the _CST method to determine C-states,
2112 instead using the legacy FADT method
2113
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002115 Format: [schedule,]<number>
2116 Param: "schedule" - profile schedule points.
2117 Param: <number> - step/bucket size as a power of 2 for
2118 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002119 Param: "sleep" - profile D-state sleeping (millisecs).
2120 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002121 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2124 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002125 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126
Randy Dunlapa9913042005-10-23 12:57:11 -07002127 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2128 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2130 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002131 psmouse.resetafter= [HW,MOUSE]
2132 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 (0 = never).
2134 psmouse.resolution=
2135 [HW,MOUSE] Set desired mouse resolution, in dpi.
2136 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002137 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002138 0 = disabled, 1 = enabled (default).
2139
2140 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002141 Format:
2142 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
2144 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002145 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146
Kay Sieversdc8c8582007-08-15 12:25:38 +02002147 pty.legacy_count=
2148 [KNL] Number of legacy pty's. Overwrites compiled-in
2149 default number.
2150
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002151 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002152
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 r128= [HW,DRM]
2154
2155 raid= [HW,RAID]
2156 See Documentation/md.txt.
2157
Randy Dunlapa9913042005-10-23 12:57:11 -07002158 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002159 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002160
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002162 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002164 rcupdate.blimit= [KNL,BOOT]
2165 Set maximum number of finished RCU callbacks to process
2166 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002167
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002168 rcupdate.qhimark= [KNL,BOOT]
2169 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002170 RCU callbacks over which batch limiting is disabled.
2171
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002172 rcupdate.qlowmark= [KNL,BOOT]
2173 Set threshold of queued RCU callbacks below which
2174 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002175
Olof Johanssonffdfc402005-09-06 15:17:19 -07002176 rdinit= [KNL]
2177 Format: <full_path>
2178 Run specified binary instead of /init from the ramdisk,
2179 used for early userspace startup. See initrd.
2180
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002181 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002183 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184
Paul Jackson46b6d942008-07-04 10:00:09 -07002185 relax_domain_level=
2186 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002187 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002188
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2190
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002191 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002192 Format: nn[KMG]
2193 Reserves a hole at the top of the kernel virtual
2194 address space.
2195
Vivek Goyal7e962872006-09-27 01:50:44 -07002196 reset_devices [KNL] Force drivers to reset the underlying device
2197 during initialization.
2198
Randy Dunlapa9913042005-10-23 12:57:11 -07002199 resume= [SWSUSP]
2200 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002202 resume_offset= [SWSUSP]
2203 Specify the offset from the beginning of the partition
2204 given by "resume=" at which the swap header is located,
2205 in <PAGE_SIZE> units (needed only for swap files).
2206 See Documentation/power/swsusp-and-swap-files.txt
2207
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002208 retain_initrd [RAM] Keep initrd memory after extraction
2209
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 rhash_entries= [KNL,NET]
2211 Set number of hash buckets for route cache
2212
2213 riscom8= [HW,SERIAL]
2214 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2215
2216 ro [KNL] Mount root device read-only on boot
2217
2218 root= [KNL] Root filesystem
2219
2220 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2221 mount the root filesystem
2222
2223 rootflags= [KNL] Set root filesystem mount option string
2224
2225 rootfstype= [KNL] Set root filesystem type
2226
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002227 rootwait [KNL] Wait (indefinitely) for root device to show up.
2228 Useful for devices that are detected asynchronously
2229 (e.g. USB and MMC devices).
2230
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231 rw [KNL] Mount root device read-write on boot
2232
2233 S [KNL] Run init in single mode
2234
2235 sa1100ir [NET]
2236 See drivers/net/irda/sa1100_ir.c.
2237
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002239
Mike Travisf6630112009-11-17 18:22:15 -06002240 sched_debug [KNL] Enables verbose scheduler debug messages.
2241
Linus Torvalds1da177e2005-04-16 15:20:36 -07002242 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2243 Format: <io>[,<timeout>[,<isapnp>]]
2244
2245 scsi_debug_*= [SCSI]
2246 See drivers/scsi/scsi_debug.c.
2247
2248 scsi_default_dev_flags=
2249 [SCSI] SCSI default device flags
2250 Format: <integer>
2251
2252 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2253 Format: <vendor>:<model>:<flags>
2254 (flags are integer value)
2255
Randy Dunlap6af66322007-11-14 16:52:25 -08002256 scsi_logging_level= [SCSI] a bit mask of logging levels
2257 See drivers/scsi/scsi_logging.h for bits. Also
2258 settable via sysctl at dev.scsi.logging_level
2259 (/proc/sys/dev/scsi/logging_level).
2260 There is also a nice 'scsi_logging_level' script in the
2261 S390-tools package, available for download at
2262 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002264 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2265 discovered. async scans them in kernel threads,
2266 allowing boot to proceed. none ignores them, expecting
2267 user space to do the scan.
2268
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002269 security= [SECURITY] Choose a security module to enable at boot.
2270 If this boot parameter is not specified, only the first
2271 security module asking for security registration will be
2272 loaded. An invalid security module name will be treated
2273 as if no module has been chosen.
2274
2275 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276 Format: { "0" | "1" }
2277 See security/selinux/Kconfig help text.
2278 0 -- disable.
2279 1 -- enable.
2280 Default value is set via kernel config option.
2281 If enabled at boot time, /selinux/disable can be used
2282 later to disable prior to initial policy load.
2283
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002284 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285
Linus Torvalds1da177e2005-04-16 15:20:36 -07002286 shapers= [NET]
2287 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002288
Yinghai Lub05f78f2008-08-22 01:32:50 -07002289 show_msr= [x86] show boot-time MSR settings
2290 Format: { <integer> }
2291 Show boot-time (BIOS-initialized) MSR settings.
2292 The parameter means the number of CPUs to show,
2293 for example 1 means boot CPU only.
2294
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295 sim710= [SCSI,HW]
2296 See header of drivers/scsi/sim710.c.
2297
2298 simeth= [IA-64]
2299 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002300
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 slram= [HW,MTD]
2302
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002303 slub_debug[=options[,slabs]] [MM, SLUB]
2304 Enabling slub_debug allows one to determine the
2305 culprit if slab objects become corrupted. Enabling
2306 slub_debug can create guard zones around objects and
2307 may poison objects when not in use. Also tracks the
2308 last alloc / free. For more information see
2309 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002310
2311 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002312 Determines the maximum allowed order for slabs.
2313 A high setting may cause OOMs due to memory
2314 fragmentation. For more information see
2315 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002316
2317 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002318 The minimum number of objects per slab. SLUB will
2319 increase the slab order up to slub_max_order to
2320 generate a sufficiently large slab able to contain
2321 the number of objects indicated. The higher the number
2322 of objects the smaller the overhead of tracking slabs
2323 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002324 For more information see Documentation/vm/slub.txt.
2325
2326 slub_min_order= [MM, SLUB]
2327 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002328 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002329 For more information see Documentation/vm/slub.txt.
2330
2331 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002332 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002333 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002334 allocs to different slabs. Debug options disable
2335 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002336 For more information see Documentation/vm/slub.txt.
2337
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 smart2= [HW]
2339 Format: <io1>[,<io2>[,...,<io8>]]
2340
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002341 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002342 attempt to substitute SMP alternatives once at boot.
2343
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002344 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2345 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2346 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2347 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2348 smsc-ircc2.ircc_irq= [HW] IRQ line
2349 smsc-ircc2.ircc_dma= [HW] DMA channel
2350 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2351 0: Toshiba Satellite 1800 (GP data pin select)
2352 1: Fast pin select (default)
2353 2: ATC IRMode
2354
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355 snd-ad1816a= [HW,ALSA]
2356
2357 snd-ad1848= [HW,ALSA]
2358
2359 snd-ali5451= [HW,ALSA]
2360
2361 snd-als100= [HW,ALSA]
2362
2363 snd-als4000= [HW,ALSA]
2364
2365 snd-azt2320= [HW,ALSA]
2366
2367 snd-cmi8330= [HW,ALSA]
2368
2369 snd-cmipci= [HW,ALSA]
2370
2371 snd-cs4231= [HW,ALSA]
2372
2373 snd-cs4232= [HW,ALSA]
2374
2375 snd-cs4236= [HW,ALSA]
2376
2377 snd-cs4281= [HW,ALSA]
2378
2379 snd-cs46xx= [HW,ALSA]
2380
2381 snd-dt019x= [HW,ALSA]
2382
2383 snd-dummy= [HW,ALSA]
2384
2385 snd-emu10k1= [HW,ALSA]
2386
2387 snd-ens1370= [HW,ALSA]
2388
2389 snd-ens1371= [HW,ALSA]
2390
2391 snd-es968= [HW,ALSA]
2392
2393 snd-es1688= [HW,ALSA]
2394
2395 snd-es18xx= [HW,ALSA]
2396
2397 snd-es1938= [HW,ALSA]
2398
2399 snd-es1968= [HW,ALSA]
2400
2401 snd-fm801= [HW,ALSA]
2402
2403 snd-gusclassic= [HW,ALSA]
2404
2405 snd-gusextreme= [HW,ALSA]
2406
2407 snd-gusmax= [HW,ALSA]
2408
2409 snd-hdsp= [HW,ALSA]
2410
2411 snd-ice1712= [HW,ALSA]
2412
2413 snd-intel8x0= [HW,ALSA]
2414
2415 snd-interwave= [HW,ALSA]
2416
2417 snd-interwave-stb=
2418 [HW,ALSA]
2419
2420 snd-korg1212= [HW,ALSA]
2421
2422 snd-maestro3= [HW,ALSA]
2423
2424 snd-mpu401= [HW,ALSA]
2425
2426 snd-mtpav= [HW,ALSA]
2427
2428 snd-nm256= [HW,ALSA]
2429
2430 snd-opl3sa2= [HW,ALSA]
2431
2432 snd-opti92x-ad1848=
2433 [HW,ALSA]
2434
2435 snd-opti92x-cs4231=
2436 [HW,ALSA]
2437
2438 snd-opti93x= [HW,ALSA]
2439
2440 snd-pmac= [HW,ALSA]
2441
2442 snd-rme32= [HW,ALSA]
2443
2444 snd-rme96= [HW,ALSA]
2445
2446 snd-rme9652= [HW,ALSA]
2447
2448 snd-sb8= [HW,ALSA]
2449
2450 snd-sb16= [HW,ALSA]
2451
2452 snd-sbawe= [HW,ALSA]
2453
2454 snd-serial= [HW,ALSA]
2455
2456 snd-sgalaxy= [HW,ALSA]
2457
2458 snd-sonicvibes= [HW,ALSA]
2459
2460 snd-sun-amd7930=
2461 [HW,ALSA]
2462
2463 snd-sun-cs4231= [HW,ALSA]
2464
2465 snd-trident= [HW,ALSA]
2466
2467 snd-usb-audio= [HW,ALSA,USB]
2468
2469 snd-via82xx= [HW,ALSA]
2470
2471 snd-virmidi= [HW,ALSA]
2472
2473 snd-wavefront= [HW,ALSA]
2474
2475 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002476
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002477 softlockup_panic=
2478 [KNL] Should the soft-lockup detector generate panics.
2479
Linus Torvalds1da177e2005-04-16 15:20:36 -07002480 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2481 See Documentation/sonypi.txt
2482
2483 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002484 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002485
2486 spia_io_base= [HW,MTD]
2487 spia_fio_base=
2488 spia_pedr=
2489 spia_peddr=
2490
2491 sscape= [HW,OSS]
2492 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002493
Linus Torvalds1da177e2005-04-16 15:20:36 -07002494 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2495 See Documentation/scsi/st.txt.
2496
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002497 stacktrace [FTRACE]
2498 Enabled the stack tracer on boot up.
2499
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 sti= [PARISC,HW]
2501 Format: <num>
2502 Set the STI (builtin display/keyboard on the HP-PARISC
2503 machines) console (graphic card) which should be used
2504 as the initial boot-console.
2505 See also comment in drivers/video/console/sticore.c.
2506
2507 sti_font= [HW]
2508 See comment in drivers/video/console/sticore.c.
2509
2510 stifb= [HW]
2511 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2512
Trond Myklebustcbf11072009-08-09 15:06:19 -04002513 sunrpc.min_resvport=
2514 sunrpc.max_resvport=
2515 [NFS,SUNRPC]
2516 SunRPC servers often require that client requests
2517 originate from a privileged port (i.e. a port in the
2518 range 0 < portnr < 1024).
2519 An administrator who wishes to reserve some of these
2520 ports for other uses may adjust the range that the
2521 kernel's sunrpc client considers to be privileged
2522 using these two parameters to set the minimum and
2523 maximum port values.
2524
Greg Banks42a7fc42007-03-06 01:42:23 -08002525 sunrpc.pool_mode=
2526 [NFS]
2527 Control how the NFS server code allocates CPUs to
2528 service thread pools. Depending on how many NICs
2529 you have and where their interrupts are bound, this
2530 option will affect which CPUs will do NFS serving.
2531 Note: this parameter cannot be changed while the
2532 NFS server is running.
2533
2534 auto the server chooses an appropriate mode
2535 automatically using heuristics
2536 global a single global pool contains all CPUs
2537 percpu one pool for each CPU
2538 pernode one pool for each NUMA node (equivalent
2539 to global on non-NUMA machines)
2540
Trond Myklebustcbf11072009-08-09 15:06:19 -04002541 sunrpc.tcp_slot_table_entries=
2542 sunrpc.udp_slot_table_entries=
2543 [NFS,SUNRPC]
2544 Sets the upper limit on the number of simultaneous
2545 RPC calls that can be sent from the client to a
2546 server. Increasing these values may allow you to
2547 improve throughput, but will also increase the
2548 amount of memory reserved for use by the client.
2549
Linus Torvalds1da177e2005-04-16 15:20:36 -07002550 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002551
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552 switches= [HW,M68k]
2553
2554 sym53c416= [HW,SCSI]
2555 See header of drivers/scsi/sym53c416.c.
2556
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002557 sysrq_always_enabled
2558 [KNL]
2559 Ignore sysrq setting - this boot parameter will
2560 neutralize any effect of /proc/sys/kernel/sysrq.
2561 Useful for debugging.
2562
Linus Torvalds1da177e2005-04-16 15:20:36 -07002563 t128= [HW,SCSI]
2564 See header of drivers/scsi/t128.c.
2565
2566 tdfx= [HW,DRM]
2567
David Brownell77437fd2008-07-23 21:28:33 -07002568 test_suspend= [SUSPEND]
2569 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2570 standby suspend) as the system sleep state to briefly
2571 enter during system startup. The system is woken from
2572 this state using a wakeup-capable RTC alarm.
2573
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 thash_entries= [KNL,NET]
2575 Set number of hash buckets for TCP connection
2576
Len Brownf8707ec2007-08-12 00:12:54 -04002577 thermal.act= [HW,ACPI]
2578 -1: disable all active trip points in all thermal zones
2579 <degrees C>: override all lowest active trip points
2580
Len Brownc52a7412007-08-14 15:49:32 -04002581 thermal.crt= [HW,ACPI]
2582 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002583 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002584
Len Brownf5487142007-08-12 00:12:44 -04002585 thermal.nocrt= [HW,ACPI]
2586 Set to disable actions on ACPI thermal zone
2587 critical and hot trip points.
2588
Len Brown72b33ef2007-08-12 00:12:17 -04002589 thermal.off= [HW,ACPI]
2590 1: disable ACPI thermal control
2591
Len Browna70cdc52007-08-12 00:12:35 -04002592 thermal.psv= [HW,ACPI]
2593 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002594 <degrees C>: override all passive trip points to this
2595 value
Len Browna70cdc52007-08-12 00:12:35 -04002596
Len Brown730ff342007-08-12 00:12:26 -04002597 thermal.tzp= [HW,ACPI]
2598 Specify global default ACPI thermal zone polling rate
2599 <deci-seconds>: poll all this frequency
2600 0: no polling (default)
2601
Linus Torvalds1da177e2005-04-16 15:20:36 -07002602 tmscsim= [HW,SCSI]
2603 See comment before function dc390_setup() in
2604 drivers/scsi/tmscsim.c.
2605
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002606 topology= [S390]
2607 Format: {off | on}
2608 Specify if the kernel should make use of the cpu
2609 topology informations if the hardware supports these.
2610 The scheduler will make use of these informations and
2611 e.g. base its process migration decisions on it.
2612 Default is off.
2613
Linus Torvalds1da177e2005-04-16 15:20:36 -07002614 tp720= [HW,PS2]
2615
Li Zefan9d612be2009-06-24 17:33:15 +08002616 trace_buf_size=nn[KMG]
2617 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002618
Li Zefan020e5f82009-07-01 10:47:05 +08002619 trace_event=[event-list]
2620 [FTRACE] Set and start specified trace events in order
2621 to facilitate early boot debugging.
2622 See also Documentation/trace/events.txt
2623
Linus Torvalds1da177e2005-04-16 15:20:36 -07002624 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002625 Format:
2626 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2627
Alok Kataria395628e2008-10-24 17:22:01 -07002628 tsc= Disable clocksource-must-verify flag for TSC.
2629 Format: <string>
2630 [x86] reliable: mark tsc clocksource as reliable, this
2631 disables clocksource verification at runtime.
2632 Used to enable high-resolution timer mode on older
2633 hardware, and in virtualized environment.
2634
Randy Dunlapa9913042005-10-23 12:57:11 -07002635 turbografx.map[2|3]= [HW,JOY]
2636 TurboGraFX parallel port interface
2637 Format:
2638 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639 See also Documentation/input/joystick-parport.txt
2640
2641 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2642 See header of drivers/scsi/u14-34f.c.
2643
2644 uart401= [HW,OSS]
2645 Format: <io>,<irq>
2646
2647 uart6850= [HW,OSS]
2648 Format: <io>,<irq>
2649
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002650 uhash_entries= [KNL,NET]
2651 Set number of hash buckets for UDP/UDP-Lite connections
2652
Alan Stern5f8364b2006-12-05 16:29:55 -05002653 uhci-hcd.ignore_oc=
2654 [USB] Ignore overcurrent events (default N).
2655 Some badly-designed motherboards generate lots of
2656 bogus events, for ports that aren't wired to
2657 anything. Set this parameter to avoid log spamming.
2658 Note that genuine overcurrent events won't be
2659 reported either.
2660
Simon Arlotte3a61b02008-07-19 23:32:54 +01002661 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302662 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002663 Set unknown_nmi_panic=1 early on boot.
2664
Alan Sternb5e795f2007-02-20 15:00:53 -05002665 usbcore.autosuspend=
2666 [USB] The autosuspend time delay (in seconds) used
2667 for newly-detected USB devices (default 2). This
2668 is the time required before an idle device will be
2669 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002670 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002671
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002672 usbcore.usbfs_snoop=
2673 [USB] Set to log all usbfs traffic (default 0 = off).
2674
2675 usbcore.blinkenlights=
2676 [USB] Set to cycle leds on hubs (default 0 = off).
2677
2678 usbcore.old_scheme_first=
2679 [USB] Start with the old device initialization
2680 scheme (default 0 = off).
2681
2682 usbcore.use_both_schemes=
2683 [USB] Try the other device initialization scheme
2684 if the first one fails (default 1 = enabled).
2685
2686 usbcore.initial_descriptor_timeout=
2687 [USB] Specifies timeout for the initial 64-byte
2688 USB_REQ_GET_DESCRIPTOR request in milliseconds
2689 (default 5000 = 5.0 seconds).
2690
Linus Torvalds1da177e2005-04-16 15:20:36 -07002691 usbhid.mousepoll=
2692 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002693
Alan Sternd4f373e2008-11-10 14:07:45 -05002694 usb-storage.delay_use=
2695 [UMS] The delay in seconds before a new device is
2696 scanned for Logical Units (default 5).
2697
2698 usb-storage.quirks=
2699 [UMS] A list of quirks entries to supplement or
2700 override the built-in unusual_devs list. List
2701 entries are separated by commas. Each entry has
2702 the form VID:PID:Flags where VID and PID are Vendor
2703 and Product ID values (4-digit hex numbers) and
2704 Flags is a set of characters, each corresponding
2705 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002706 a = SANE_SENSE (collect more than 18 bytes
2707 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002708 b = BAD_SENSE (don't collect more than 18
2709 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002710 c = FIX_CAPACITY (decrease the reported
2711 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002712 h = CAPACITY_HEURISTICS (decrease the
2713 reported device capacity by one
2714 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002715 i = IGNORE_DEVICE (don't bind to this
2716 device);
2717 l = NOT_LOCKABLE (don't try to lock and
2718 unlock ejectable media);
2719 m = MAX_SECTORS_64 (don't transfer more
2720 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002721 o = CAPACITY_OK (accept the capacity
2722 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002723 r = IGNORE_RESIDUE (the device reports
2724 bogus residue values);
2725 s = SINGLE_LUN (the device has only one
2726 Logical Unit);
2727 w = NO_WP_DETECT (don't test whether the
2728 medium is write-protected).
2729 Example: quirks=0419:aaf5:rl,0421:0433:rc
2730
Ian Campbell14315592010-02-17 10:38:10 +00002731 userpte=
2732 [X86] Flags controlling user PTE allocations.
2733
2734 nohigh = do not allocate PTE pages in
2735 HIGHMEM regardless of setting
2736 of CONFIG_HIGHPTE.
2737
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302738 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002739 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002740 vdso=1: enable VDSO (default)
2741 vdso=0: disable VDSO mapping
2742
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302743 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002744 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2745 vdso32=1: enable 32-bit VDSO (default)
2746 vdso32=0: disable 32-bit VDSO mapping
2747
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002748 vector= [IA-64,SMP]
2749 vector=percpu: enable percpu vector domain
2750
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751 video= [FB] Frame buffer configuration
2752 See Documentation/fb/modedb.txt.
2753
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002754 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002755 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002756 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002757 Use vga=ask for menu.
2758 This is actually a boot loader parameter; the value is
2759 passed to the kernel using a special protocol.
2760
Randy Dunlapa9913042005-10-23 12:57:11 -07002761 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002762 size of <nn>. This can be used to increase the
2763 minimum size (128MB on x86). It can also be used to
2764 decrease the size and leave more room for directly
2765 mapped kernel RAM.
2766
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002767 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2768 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002769
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002770 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2771 Format: <command>
2772
2773 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2774 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002775
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002776 vt.cur_default= [VT] Default cursor shape.
2777 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2778 the parameters of the <Esc>[?A;B;Cc escape sequence;
2779 see VGA-softcursor.txt. Default: 2 = underline.
2780
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002781 vt.default_blu= [VT]
2782 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2783 Change the default blue palette of the console.
2784 This is a 16-member array composed of values
2785 ranging from 0-255.
2786
2787 vt.default_grn= [VT]
2788 Format: <green0>,<green1>,<green2>,...,<green15>
2789 Change the default green palette of the console.
2790 This is a 16-member array composed of values
2791 ranging from 0-255.
2792
2793 vt.default_red= [VT]
2794 Format: <red0>,<red1>,<red2>,...,<red15>
2795 Change the default red palette of the console.
2796 This is a 16-member array composed of values
2797 ranging from 0-255.
2798
2799 vt.default_utf8=
2800 [VT]
2801 Format=<0|1>
2802 Set system-wide default UTF-8 mode for all tty's.
2803 Default is 1, i.e. UTF-8 mode is enabled for all
2804 newly opened terminals.
2805
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002806 vt.global_cursor_default=
2807 [VT]
2808 Format=<-1|0|1>
2809 Set system-wide default for whether a cursor
2810 is shown on new VTs. Default is -1,
2811 i.e. cursors will be created by default unless
2812 overridden by individual drivers. 0 will hide
2813 cursors, 1 will display them.
2814
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815 waveartist= [HW,OSS]
2816 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002817
Linus Torvalds1da177e2005-04-16 15:20:36 -07002818 wd33c93= [HW,SCSI]
2819 See header of drivers/scsi/wd33c93.c.
2820
2821 wd7000= [HW,SCSI]
2822 See header of drivers/scsi/wd7000.c.
2823
2824 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002825 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002827 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2828 default x2apic cluster mode on platforms
2829 supporting x2apic.
2830
Linus Torvalds1da177e2005-04-16 15:20:36 -07002831 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2832 xd_geo= See header of drivers/block/xd.c.
2833
2834 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002835 Format:
2836 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002837
Randy Dunlapa9913042005-10-23 12:57:11 -07002838______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839
2840TODO:
2841
2842 Add documentation for ALSA options.
2843 Add more DRM drivers.