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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070043 ARM ARM architecture is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020044 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080046 BLACKFIN Blackfin architecture is enabled.
Alan Cox9cfe2682011-01-25 14:18:38 +000047 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
Mimi Zohar7102ebc2011-05-12 18:33:20 -040052 EVM Extended Verification Module
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 FB The frame buffer device is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070054 FTRACE Function tracing enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070055 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050058 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070060 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080061 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050065 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020066 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070067 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070075 MIPS MIPS architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070077 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070078 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070083 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070087 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
Randy Dunlap163475f2010-08-14 12:36:14 -070096 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
James Morris20510f22007-10-16 23:31:32 -070098 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 SELINUX SELinux support is enabled.
John Johansenc1c124e2010-07-29 14:48:09 -0700100 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +0900102 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300107 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500109 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700117 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700120 Documentation/x86/x86_64/boot-options.txt .
Randy Dunlap16290242011-08-13 12:34:52 -0700121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100122 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
124In addition, the following text indicates that the option:
125
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
129
130Parameters denoted with BOOT are actually interpreted by the boot
131loader, and have no meaning to the kernel directly.
132Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500133need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
Karsten Weiss55588702007-02-13 13:26:21 +0100135There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700136See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100137
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139a trailing = on the name of any parameter states that that parameter will
140be entered as an environment variable, whereas its absence indicates that
141it will appear as a kernel argument readable via /proc/cmdline by programs
142running once the system is up.
143
jens m. noedler9c4751f2006-09-29 02:00:27 -0700144The number of kernel parameters is not limited, but the length of the
145complete command line (parameters including spaces etc.) is limited to
146a fixed number of characters. This limit depends on the architecture
147and is between 256 and 4096 characters. It is defined in the file
148./include/asm/setup.h as COMMAND_LINE_SIZE.
149
Ahmed S. Darwish7a19a232011-02-20 20:08:35 -0800150Finally, the [KMG] suffix is commonly described after a number of kernel
151parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153bytes respectively. Such letter suffixes can also be entirely omitted.
154
jens m. noedler9c4751f2006-09-29 02:00:27 -0700155
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530156 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800157 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500158 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700162 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800164 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800165 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Paul Bolle395cf962011-08-15 02:02:26 +0200167 See also Documentation/power/runtime_pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
Takao Indoh4996c022011-07-14 18:05:21 -0400169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
173
Len Browna1fdcc02007-03-11 03:26:14 -0400174 acpi_apic_instance= [ACPI, IOAPIC]
175 Format: <int>
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400178 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400179
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
182 acpi_backlight=video
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
186
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200210
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800214
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
217 default in APIC mode
218
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
221 default in PIC mode
222
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
225
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
227 use by PCI
228 Format: <irq>,<irq>...
229
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
231
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
234
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
239
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530240 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
244
Randy Dunlap4af94f32009-04-17 18:30:28 -0700245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
247
248 acpi_serialize [HW,ACPI] force serialization of AML methods
249
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
253
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Amerigo Wangc3b07952011-05-10 21:09:38 +0200256 old_ordering, nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700257 See Documentation/power/video.txt for information on
258 s3_bios and s3_mode.
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700272
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
276
Luca Tettamanti7e905602009-03-30 00:01:27 +0200277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
292
Randy Dunlap4af94f32009-04-17 18:30:28 -0700293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
295
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
Randy Dunlapbcfde332010-06-07 17:10:38 -0700302 ALSA [HW,ALSA]
303 See Documentation/sound/alsa/alsa-parameters.txt
304
Russell Kingd944d542010-02-20 16:13:29 +0000305 alignment= [KNL,ARM]
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
309
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
317
318 1: only for 32-bit processes
319 2: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
322
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200323 amd_iommu= [HW,X86-84]
324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
329 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200330 off - do not initialize any AMD IOMMU found in
331 the system
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900332
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
335 Format: <a>,<b>
Paul Bolle395cf962011-08-15 02:02:26 +0200336 See also Documentation/input/joystick.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
342
Randy Dunlapa9913042005-10-23 12:57:11 -0700343 apc= [HW,SPARC]
344 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 Format: noidle
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
349
Randy Dunlapca1eda22009-05-06 16:02:58 -0700350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700351 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700355
Brian Haleyb0f83b22010-02-04 13:36:50 -0800356 autoconf= [IPV6]
357 See Documentation/networking/ipv6.txt.
358
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700369 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
373
374 ataflop= [HW,M68k]
375
376 atarimouse= [HW,MOUSE] Atari Mouse
377
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
380
381 atkbd.reset= [HW] Reset keyboard during initialization
382
Randy Dunlapa9913042005-10-23 12:57:11 -0700383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
387 keyboards
388
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700391
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394
Randy Dunlap16290242011-08-13 12:34:52 -0700395 autotest [IA-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 baycom_epp= [HW,AX25]
398 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700399
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
401 Format: <io>,<mode>
402 See header of drivers/net/hamradio/baycom_par.c.
403
Randy Dunlapa9913042005-10-23 12:57:11 -0700404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
408
Randy Dunlapa9913042005-10-23 12:57:11 -0700409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
413
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
416 no delay (0).
417 Format: integer
418
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
420
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700422 bttv.radio= Most important insmod options are available as
423 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
Paul Bolle395cf962011-08-15 02:02:26 +0200425 bttv.tuner=
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000427 bulk_remove=off [PPC] This parameter disables the use of the pSeries
428 firmware feature for flushing multiple hpte entries
429 at a time.
430
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 c101= [NET] Moxa C101 synchronous serial card
432
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
439
James Morris20510f22007-10-16 23:31:32 -0700440 capability.disable=
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
445
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
Paul Menage8bab8dd2008-04-04 14:29:57 -0700449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
452
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700460 Value can be changed at runtime via
461 /selinux/checkreqprot.
462
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100463 cio_ignore= [S390]
464 See Documentation/s390/CommonIO for details.
465
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700467 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200468 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700469 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200470 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 Format: { pit | tsc | cyclone | pmtmr }
472
John Stultz592913e2010-07-13 17:56:20 -0700473 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700474 Format: <string>
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
478 the platform:
479 [all] jiffies (this is the base, fallback clocksource)
480 [ACPI] acpi_pm
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
483 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700484 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700485 scx200_hrt on Geode; cyclone on IBM x440
486 [MIPS] MIPS
487 [PARISC] cr16
488 [S390] tod
489 [SH] SuperH
490 [SPARC64] tick
491 [X86-64] hpet,tsc
492
Andi Kleenac72e782008-01-30 13:33:21 +0100493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100497 stable over kernel options, but the vendor specific
498 ones should be.
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
504 some critical bits.
505
Robert Jennings14f966e2009-04-15 05:55:32 +0000506 cmo_free_hint= [PPC] Format: { yes | no }
507 Specify whether pages are marked as being inactive
508 when they are freed. This is used in CMO environments
509 to determine OS memory pressure for page stealing by
510 a hypervisor.
511 Default: yes
512
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530513 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100514 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100515 Range: 0 - 8192
516 Default: 64
517
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700519 Format:
520 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521
522 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
523 Format: <io>[,<irq>]
524
Randy Dunlapa9913042005-10-23 12:57:11 -0700525 com90xx= [HW,NET]
526 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 Format: <io>[,<irq>[,<memstart>]]
528
529 condev= [HW,S390] console device
530 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700531
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 console= [KNL] Output console device and options.
533
534 tty<n> Use the virtual console device <n>.
535
536 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800537 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800539 the form "bbbbpnf", where "bbbb" is the baud rate,
540 "p" is parity ("n", "o", or "e"), "n" is number of
541 bits, and "f" is flow control ("r" for RTS or
542 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800544 See Documentation/serial-console.txt for more
545 information. See
546 Documentation/networking/netconsole.txt for an
547 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address,
553 switching to the matching ttyS device later. The
554 options are the same as for ttyS, above.
555
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700556 If the device connected to the port is not a TTY but a braille
557 device, prepend "brl," before the device type, for instance
558 console=brl,ttyS0
559 For now, only VisioBraille is supported.
560
Daniel Mackf324edc2009-06-16 15:33:52 -0700561 consoleblank= [KNL] The console blank (screen saver) timeout in
562 seconds. Defaults to 10*60 = 10mins. A value of 0
563 disables the blank timer.
564
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800565 coredump_filter=
566 [KNL] Change the default value for
567 /proc/<pid>/coredump_filter.
568 See also Documentation/filesystems/proc.txt.
569
Len Brown62027ae2011-04-01 18:13:10 -0400570 cpuidle.off=1 [CPU_IDLE]
571 disable the cpuidle sub-system
572
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700574 Format:
575 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800577 crashkernel=size[KMG][@offset[KMG]]
578 [KNL] Using kexec, Linux can switch to a 'crash kernel'
579 upon panic. This parameter reserves the physical
580 memory region [offset, offset + size] for that kernel
581 image. If '@offset' is omitted, then a suitable offset
582 is selected automatically. Check
583 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700584
Bernhard Wallefb391592007-10-18 23:41:02 -0700585 crashkernel=range1:size1[,range2:size2,...][@offset]
586 [KNL] Same as above, but depends on the memory
587 in the running system. The syntax of range is
588 start-[end] where start and end are both
589 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800590 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700591
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 cs89x0_dma= [HW,NET]
593 Format: <dma>
594
595 cs89x0_media= [HW,NET]
596 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700597
Randy Dunlapa9913042005-10-23 12:57:11 -0700598 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 See header of drivers/s390/block/dasd_devmap.c.
600
601 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
602 (one device per port)
603 Format: <port#>,<type>
604 See also Documentation/input/joystick-parport.txt
605
Thomas Renningera648ec02010-08-06 16:11:02 +0200606 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
607 time. See Documentation/dynamic-debug-howto.txt for
608 details.
609
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 debug [KNL] Enable kernel debugging (events log level).
611
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700612 debug_locks_verbose=
613 [KNL] verbose self-tests
614 Format=<0|1>
615 Print debugging info while doing the locking API
616 self-tests.
617 We default to 0 (no extra messages), setting it to
618 1 will print _a lot_ more information - normally
619 only useful to kernel developers.
620
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700621 debug_objects [KNL] Enable object debugging
622
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500623 no_debug_objects
624 [KNL] Disable object debugging
625
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200626 debugpat [X86] Enable PAT debugging
627
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200628 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 Format: <area>[,<node>]
630 See also Documentation/networking/decnet.txt.
631
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700632 default_hugepagesz=
633 [same as hugepagesz=] The size of the default
634 HugeTLB page size. This is the size represented by
635 the legacy /proc/ hugepages APIs, used for SHM, and
636 default size when mounting hugetlbfs filesystems.
637 Defaults to the default architecture's huge page size
638 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700639
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 dhash_entries= [KNL]
641 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700642
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 digi= [HW,SERIAL]
644 IO parameters + enable/disable command.
645
646 digiepca= [HW,SERIAL]
647 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000648 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649
Brian Haleyb0f83b22010-02-04 13:36:50 -0800650 disable= [IPV6]
651 See Documentation/networking/ipv6.txt.
652
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000653 disable_ddw [PPC/PSERIES]
654 Disable Dynamic DMA Window support. Use this if
655 to workaround buggy firmware.
656
Brian Haleyb0f83b22010-02-04 13:36:50 -0800657 disable_ipv6= [IPV6]
658 See Documentation/networking/ipv6.txt.
659
Yinghai Lu95ffa242008-04-29 03:52:33 -0700660 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700661 The kernel tries to adjust MTRR layout from continuous
662 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700663 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700664
Yinghai Lu093af8d2008-01-30 13:33:32 +0100665 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100666 By default the kernel will trim any uncacheable
667 memory out of your available memory pool based on
668 MTRR settings. This parameter disables that behavior,
669 possibly causing your machine to run very slowly.
670
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530671 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700672 Disable PIN 1 of APIC timer
673 Can be useful to work around chipset bugs.
674
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700675 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
676 this option disables the debugging code at boot.
677
678 dma_debug_entries=<number>
679 This option allows to tune the number of preallocated
680 entries for DMA-API debugging code. One entry is
681 required per DMA-API allocation. Use this if the
682 DMA-API debugging code disables itself because the
683 architectural default is too low.
684
Joerg Roedel1745de52009-05-22 21:49:51 +0200685 dma_debug_driver=<driver_name>
686 With this option the DMA-API debugging driver
687 filter feature can be enabled at boot time. Just
688 pass the driver to filter for as the parameter.
689 The filter can be disabled or changed to another
690 driver later using sysfs.
691
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 dscc4.setup= [NET]
693
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700694 earlycon= [KNL] Output early console device and options.
695 uart[8250],io,<addr>[,options]
696 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700697 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700698 Start an early, polled-mode console on the 8250/16550
699 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700700 MMIO inter-register address stride is either 8-bit
701 (mmio) or 32-bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700702 The options are the same as for ttyS, above.
703
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530704 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 earlyprintk=vga
706 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500707 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500708 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709
Randy Dunlapa9913042005-10-23 12:57:11 -0700710 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 takes over.
712
Yinghai Lu5c059172008-07-24 17:29:40 -0700713 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714
715 Currently only ttyS0 and ttyS1 are supported.
716
717 Interaction with the standard serial driver is not
718 very good.
719
720 The VGA output is eventually overwritten by the real
721 console.
722
Jason Wessel97311912010-05-20 21:04:30 -0500723 ekgdboc= [X86,KGDB] Allow early kernel console debugging
724 ekgdboc=kbd
725
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300726 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500727 the boot argument: earlyprintk=vga
728
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700730 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 eisa_irq_edge= [PARISC,HW]
733 See header of drivers/parisc/eisa.c.
734
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700735 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700737 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
739 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100740 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +0200741 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -0700742 Documentation/block/deadline-iosched.txt for details.
743
Michael Holzheud3bf3792011-10-30 15:16:37 +0100744 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -0700745 Specifies physical address of start of kernel core
Michael Holzheud3bf3792011-10-30 15:16:37 +0100746 image elf header and optionally the size. Generally
747 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -0800748 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700750 enable_mtrr_cleanup [X86]
751 The kernel tries to adjust MTRR layout from continuous
752 to discrete, to make X server driver able to add WB
753 entry later. This parameter enables that.
754
Randy Dunlapca1eda22009-05-06 16:02:58 -0700755 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700756 Enable PIN 1 of APIC timer
757 Can be useful to work around chipset bugs
758 (in particular on some ATI chipsets).
759 The kernel tries to set a reasonable default.
760
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 enforcing [SELINUX] Set initial enforcing status.
762 Format: {"0" | "1"}
763 See security/selinux/Kconfig help text.
764 0 -- permissive (log only, no denials).
765 1 -- enforcing (deny and log).
766 Default value is 0.
767 Value can be changed at runtime via /selinux/enforce.
768
Huang Yinga08f82d2010-05-18 14:35:21 +0800769 erst_disable [ACPI]
770 Disable Error Record Serialization Table (ERST)
771 support.
772
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 ether= [HW,NET] Ethernet cards parameters
774 This option is obsoleted by the "netdev=" option, which
775 has equivalent usage. See its documentation for details.
776
Mimi Zohar7102ebc2011-05-12 18:33:20 -0400777 evm= [EVM]
778 Format: { "fix" }
779 Permit 'security.evm' to be updated regardless of
780 current integrity status.
781
Akinobu Mitade1ba092006-12-08 02:39:42 -0800782 failslab=
783 fail_page_alloc=
784 fail_make_request=[KNL]
785 General fault injection mechanism.
786 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +0200787 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -0800788
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000790 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791
Alex Chiangf13ae302008-05-08 14:03:23 -0600792 force_pal_cache_flush
793 [IA-64] Avoid check_sal_cache_flush which may hang on
794 buggy SAL_CACHE_FLUSH implementations. Using this
795 parameter will force ia64_sal_cache_flush to call
796 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
797
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100798 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400799 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100800 as early as possible in order to facilitate early
801 boot debugging.
802
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200803 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400804 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200805 If no parameter is passed, ftrace will dump
806 buffers of all CPUs, but if you pass orig_cpu, it will
807 dump only the buffer of the CPU that triggered the
808 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400809
810 ftrace_filter=[function-list]
811 [FTRACE] Limit the functions traced by the function
812 tracer at boot up. function-list is a comma separated
813 list of functions. This list can be changed at run
814 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -0700815 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400816
817 ftrace_notrace=[function-list]
818 [FTRACE] Do not trace the functions specified in
819 function-list. This list can be changed at run time
820 by the set_ftrace_notrace file in the debugfs
821 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100822
Stefan Assmann369bc182009-10-12 22:17:21 +0200823 ftrace_graph_filter=[function-list]
824 [FTRACE] Limit the top level callers functions traced
825 by the function graph tracer at boot up.
826 function-list is a comma separated list of functions
827 that can be changed at run time by the
828 set_graph_function file in the debugfs tracing directory.
829
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 gamecon.map[2|3]=
831 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
832 support via parallel port (up to 5 devices per port)
833 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
834 See also Documentation/input/joystick-parport.txt
835
836 gamma= [HW,DRM]
837
Yinghai Luaaf23042008-01-30 13:33:09 +0100838 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
839 Format: off | on
840 default: on
841
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700842 gcov_persist= [GCOV] When non-zero (default), profiling data for
843 kernel modules is saved and remains accessible via
844 debugfs, even when the module is unloaded/reloaded.
845 When zero, profiling data is discarded and associated
846 debugfs files are removed at module unload time.
847
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 gpt [EFI] Forces disk with valid GPT signature but
849 invalid Protective MBR to be treated as GPT.
850
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 hashdist= [KNL,NUMA] Large hashes allocated during boot
852 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -0700853 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700854 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
856 hcl= [IA-64] SGI's Hardware Graph compatibility layer
857
858 hd= [EIDE] (E)IDE hard drive subsystem geometry
859 Format: <cyl>,<head>,<sect>
860
Huang Yingea8c0712010-05-18 14:35:15 +0800861 hest_disable [ACPI]
862 Disable Hardware Error Source Table (HEST) support;
863 corresponding firmware-first mode error processing
864 logic will be disabled.
865
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
867 size of <nn>. This works even on boxes that have no
868 highmem otherwise. This also works to reduce highmem
869 size on bigger boxes.
870
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800871 highres= [KNL] Enable/disable high resolution timer mode.
872 Valid parameters: "on", "off"
873 Default: "on"
874
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 hisax= [HW,ISDN]
876 See Documentation/isdn/README.HiSax.
877
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700878 hlt [BUGS=ARM,SH]
879
880 hpet= [X86-32,HPET] option to control HPET usage
881 Format: { enable (default) | disable | force |
882 verbose }
883 disable: disable HPET and use PIT instead
884 force: allow force enabled of undocumented chips (ICH4,
885 VIA, nVidia)
886 verbose: show contents of HPET registers during setup
887
Andi Kleenb4718e62008-07-23 21:27:51 -0700888 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
889 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700890 On x86-64 and powerpc, this option can be specified
891 multiple times interleaved with hugepages= to reserve
892 huge pages of different sizes. Valid pages sizes on
893 x86-64 are 2M (when the CPU supports "pse") and 1G
894 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700895 Note that 1GB pages can only be allocated at boot time
896 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900897
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100898 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
899 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100900 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
901 If specified, z/VM IUCV HVC accepts connections
902 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100903
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700904 keep_bootcon [KNL]
905 Do not unregister boot console at start. This is only
906 useful for debugging when something happens in the window
907 between unregistering the boot console and initializing
908 the real console.
909
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700910 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700911 or register an additional I2C bus that is not
912 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700913 Format:
914 <bus_id>,<clkrate>
915
Jiri Kosina36d95732008-10-06 02:51:09 -0400916 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200918 i8042.dumbkbd [HW] Pretend that controller can only read data from
919 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 (Don't attempt to blink the leds)
921 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500922 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400923 i8042.noloop [HW] Disable the AUX Loopback command while probing
924 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 i8042.nomux [HW] Don't check presence of an active multiplexing
926 controller
927 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
928 controllers
Jiri Kosinaf8313ef2011-01-08 01:37:26 -0800929 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 i8042.reset [HW] Reset the controller during init and cleanup
931 i8042.unlock [HW] Unlock (ignore) the keylock
932
933 i810= [HW,DRM]
934
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700935 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
936 indicates that the driver is running on unsupported
937 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
939 does not match list of supported models.
940 i8k.power_status
941 [HW] Report power status in /proc/i8k
942 (disabled by default)
943 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
944 capability is set.
945
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 icn= [HW,ISDN]
947 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
948
David Fries0af80c02009-02-25 20:28:21 +0100949 ide-core.nodma= [HW] (E)IDE subsystem
950 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200951 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
952 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100953 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700955 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
956 Claim all unknown PCI IDE storage controllers.
957
Andi Kleenf039b752007-05-02 19:27:12 +0200958 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800959 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
960 Poll forces a polling idle loop that can slightly
961 improve the performance of waking up a idle CPU, but
962 will use a lot of power and make the system run hot.
963 Not recommended.
964 idle=mwait: On systems which support MONITOR/MWAIT but
965 the kernel chose to not use it because it doesn't save
966 as much power as a normal idle loop, use the
967 MONITOR/MWAIT idle loop anyways. Performance should be
968 the same as idle=poll.
969 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800970 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800971 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700972
Ingo Molnar792908222006-12-06 20:40:51 -0800973 ignore_loglevel [KNL]
974 Ignore loglevel setting - this will print /all/
975 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -0700976 We also add it as printk module parameter, so users
977 could change it dynamically, usually by
978 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -0800979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 ihash_entries= [KNL]
981 Set number of hash buckets for inode cache.
982
Mimi Zohar3323eec2009-02-04 09:06:58 -0500983 ima_audit= [IMA]
984 Format: { "0" | "1" }
985 0 -- integrity auditing messages. (Default)
986 1 -- enable informational integrity auditing messages.
987
988 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -0700989 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -0500990 default: "sha1"
991
Eric Paris5789ba32009-05-21 15:47:06 -0400992 ima_tcb [IMA]
993 Load a policy which meets the needs of the Trusted
994 Computing Base. This means IMA will measure all
995 programs exec'd, files mmap'd for exec, and all files
996 opened for read by uid=0.
997
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 init= [KNL]
999 Format: <full_path>
1000 Run specified binary instead of /sbin/init as init
1001 process.
1002
1003 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1004 for working out where the kernel is dying during
1005 startup.
1006
1007 initrd= [BOOT] Specify the location of the initial ramdisk
1008
1009 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1010 Format: <irq>
1011
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001012 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001013 on
1014 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001015 off
1016 Disable intel iommu driver.
1017 igfx_off [Default Off]
1018 By default, gfx is mapped as normal device. If a gfx
1019 device has a dedicated DMAR unit, the DMAR unit is
1020 bypassed by not enabling DMAR with this option. In
1021 this case, gfx device will use physical address for
1022 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001023 forcedac [x86_64]
1024 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001025 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001026 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001027 than 32-bit addressing. The default is to look
1028 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001029 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001030 strict [Default Off]
1031 With this option on every unmap_single operation will
1032 result in a hardware IOTLB flush operation as opposed
1033 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001034 sp_off [Default Off]
1035 By default, super page will be supported if Intel IOMMU
1036 has the capability. With this option, super page will
1037 not be supported.
Chris Wrightd1423d52010-07-20 11:06:49 -07001038 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001039 on enable Interrupt Remapping (default)
1040 off disable Interrupt Remapping
1041 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001042 no_x2apic_optout
1043 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001044
Randy Dunlap16290242011-08-13 12:34:52 -07001045 inttest= [IA-64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001046
1047 iomem= Disable strict checking of access to MMIO memory
1048 strict regions from userspace.
1049 relaxed
1050
1051 iommu= [x86]
1052 off
1053 force
1054 noforce
1055 biomerge
1056 panic
1057 nopanic
1058 merge
1059 nomerge
1060 forcesac
1061 soft
Randy Dunlap16290242011-08-13 12:34:52 -07001062 pt [x86, IA-64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001063
1064 io7= [HW] IO7 for Marvel based alpha systems
1065 See comment before marvel_specify_io7 in
1066 arch/alpha/kernel/core_marvel.c.
1067
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301068 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001069 0x80
1070 Standard port 0x80 based delay
1071 0xed
1072 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001073 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001074 Simple two microseconds delay
1075 none
1076 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001077
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001079 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080
1081 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001082 See comment before ip2_setup() in
1083 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084
Alan Cox200803d2005-06-28 20:45:18 -07001085 irqfixup [HW]
1086 When an interrupt is not handled search all handlers
1087 for it. Intended to get systems with badly broken
1088 firmware running.
1089
1090 irqpoll [HW]
1091 When an interrupt is not handled search all handlers
1092 for it. Also check all handlers each timer
1093 interrupt. Intended to get systems with badly broken
1094 firmware running.
1095
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001097 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098
1099 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001100 Format:
1101 <cpu number>,...,<cpu number>
1102 or
Li Zefanb225d442008-11-06 12:53:39 -08001103 <cpu number>-<cpu number>
1104 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001105 or a mixture
1106 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001107
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 This option can be used to specify one or more CPUs
1109 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001110 algorithms. You can move a process onto or off an
1111 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 <cpu number> begins at 0 and the maximum value is
1113 "number of CPUs in system - 1".
1114
1115 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001116 alternative -- manually setting the CPU mask of all
1117 tasks in the system -- can cause problems and
1118 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119
Randy Dunlapa9913042005-10-23 12:57:11 -07001120 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121
1122 js= [HW,JOY] Analog joystick
1123 See Documentation/input/joystick.txt.
1124
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001125 keepinitrd [HW,ARM]
1126
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301127 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001128 specifies the amount of memory usable by the kernel
1129 for non-movable allocations. The requested amount is
1130 spread evenly throughout all nodes in the system. The
1131 remaining memory in each node is used for Movable
1132 pages. In the event, a node is too small to have both
1133 kernelcore and Movable pages, kernelcore pages will
1134 take priority and other nodes will have a larger number
1135 of kernelcore pages. The Movable zone is used for the
1136 allocation of pages that may be reclaimed or moved
1137 by the page migration subsystem. This means that
1138 HugeTLB pages may not be allocated from this zone.
1139 Note that allocations like PTEs-from-HighMem still
1140 use the HighMem zone if it exists, and the Normal
1141 zone if it does not.
1142
Jason Wessel4fe1da42010-05-20 21:04:31 -05001143 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1144 Format: <Controller#>[,poll interval]
1145 The controller # is the number of the ehci usb debug
1146 port as it is probed via PCI. The poll interval is
1147 optional and is the number seconds in between
1148 each poll cycle to the debug port in case you need
1149 the functionality for interrupting the kernel with
1150 gdb or control-c on the dbgp connection. When
1151 not using this parameter you use sysrq-g to break into
1152 the kernel debugger.
1153
Jason Wessel84c08fd2010-05-20 21:04:24 -05001154 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001155 Requires a tty driver that supports console polling,
1156 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001157 Serial only format: <serial_device>[,baud]
1158 keyboard only format: kbd
1159 keyboard and serial format: kbd,<serial_device>[,baud]
1160 Optional Kernel mode setting:
1161 kms, kbd format: kms,kbd
1162 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001163
Jason Wessel84c08fd2010-05-20 21:04:24 -05001164 kgdbwait [KGDB] Stop kernel execution and enter the
1165 kernel debugger at the earliest opportunity.
1166
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001167 kmac= [MIPS] korina ethernet MAC address.
1168 Configure the RouterBoard 532 series on-chip
1169 Ethernet adapter MAC address.
1170
Catalin Marinas04f70332009-06-11 13:22:39 +01001171 kmemleak= [KNL] Boot-time kmemleak enable/disable
1172 Valid arguments: on, off
1173 Default: on
1174
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301175 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001176 in oops dumps.
1177
Andre Przywarafef07aa2009-07-10 14:20:35 +02001178 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1179 Default is 0 (don't ignore, but inject #GP)
1180
1181 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1182 Default is 1 (enabled)
1183
Xiao Guangronga182d872010-09-20 22:17:48 +08001184 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1185 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001186 Default is 0 (off)
1187
Andre Przywarafef07aa2009-07-10 14:20:35 +02001188 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001189 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001190
1191 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1192 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001193 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001194
Andre Przywarafef07aa2009-07-10 14:20:35 +02001195 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1196 (virtualized MMU) support on capable Intel chips.
1197 Default is 1 (enabled)
1198
1199 kvm-intel.emulate_invalid_guest_state=
1200 [KVM,Intel] Enable emulation of invalid guest states
1201 Default is 0 (disabled)
1202
1203 kvm-intel.flexpriority=
1204 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1205 Default is 1 (enabled)
1206
Sasha Levine1a72ae2011-08-09 14:28:35 +03001207 kvm-intel.nested=
1208 [KVM,Intel] Enable VMX nesting (nVMX).
1209 Default is 0 (disabled)
1210
Andre Przywarafef07aa2009-07-10 14:20:35 +02001211 kvm-intel.unrestricted_guest=
1212 [KVM,Intel] Disable unrestricted guest feature
1213 (virtualized real and unpaged mode) on capable
1214 Intel chips. Default is 1 (enabled)
1215
1216 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1217 feature (tagged TLBs) on capable Intel chips.
1218 Default is 1 (enabled)
1219
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 l2cr= [PPC]
1221
Robert Brosea78bfbf2008-03-29 07:20:23 +11001222 l3cr= [PPC]
1223
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001224 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001225 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301227 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001228 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001229
FD Camifcb71f62008-01-06 19:08:56 +01001230 libata.dma= [LIBATA] DMA control
1231 libata.dma=0 Disable all PATA and SATA DMA
1232 libata.dma=1 PATA and SATA Disk DMA only
1233 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001234 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001235 Combinations also work, so libata.dma=3 enables DMA
1236 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001237
Michael Prokop20308872009-08-06 00:14:10 +02001238 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1239 libata.ignore_hpa=0 keep BIOS limits (default)
1240 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001241
Dave Jones78e70c22007-09-27 11:50:13 -04001242 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1243 when set.
1244 Format: <int>
1245
Tejun Heo33267322008-02-13 09:15:09 +09001246 libata.force= [LIBATA] Force configurations. The format is comma
1247 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001248 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001249 matching port, link or device. Basically, it matches
1250 the ATA ID string printed on console by libata. If
1251 the whole ID part is omitted, the last PORT and DEVICE
1252 values are used. If ID hasn't been specified yet, the
1253 configuration applies to all ports, links and devices.
1254
1255 If only DEVICE is omitted, the parameter applies to
1256 the port and all links and devices behind it. DEVICE
1257 number of 0 either selects the first device or the
1258 first fan-out link behind PMP device. It does not
1259 select the host link. DEVICE number of 15 selects the
1260 host link and device attached to it.
1261
1262 The VAL specifies the configuration to force. As long
1263 as there's no ambiguity shortcut notation is allowed.
1264 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1265 The following configurations can be forced.
1266
1267 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1268 Any ID with matching PORT is used.
1269
1270 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1271
1272 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1273 udma[/][16,25,33,44,66,100,133] notation is also
1274 allowed.
1275
1276 * [no]ncq: Turn on or off NCQ.
1277
Tejun Heo05944bd2008-08-13 20:19:09 +09001278 * nohrst, nosrst, norst: suppress hard, soft
1279 and both resets.
1280
Tejun Heo43c9c592010-05-23 12:59:11 +02001281 * dump_id: dump IDENTIFY data.
1282
Tejun Heo33267322008-02-13 09:15:09 +09001283 If there are multiple matching configurations changing
1284 the same attribute, the last one is used.
1285
Yinghai Lu95f72d12010-07-12 14:36:09 +10001286 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001287
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001289 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001291 lockd.nlm_grace_period=P [NFS] Assign grace period.
1292 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001294 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1295 Format: <integer>
1296
1297 lockd.nlm_timeout=T [NFS] Assign timeout value.
1298 Format: <integer>
1299
1300 lockd.nlm_udpport=M [NFS] Assign UDP port.
1301 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302
1303 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1304 Format: <irq>
1305
1306 loglevel= All Kernel Messages with a loglevel smaller than the
1307 console loglevel will be printed to the console. It can
1308 also be changed with klogd or other programs. The
1309 loglevels are defined as follows:
1310
1311 0 (KERN_EMERG) system is unusable
1312 1 (KERN_ALERT) action must be taken immediately
1313 2 (KERN_CRIT) critical conditions
1314 3 (KERN_ERR) error conditions
1315 4 (KERN_WARNING) warning conditions
1316 5 (KERN_NOTICE) normal but significant condition
1317 6 (KERN_INFO) informational
1318 7 (KERN_DEBUG) debug-level messages
1319
Randy Dunlapc756d082011-02-20 20:08:35 -08001320 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1321 in bytes. n must be a power of two. The default
1322 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323
Randy Dunlapaccaa242007-10-16 01:29:37 -07001324 logo.nologo [FB] Disables display of the built-in Linux logo.
1325 This may be used to provide more screen space for
1326 kernel log messages and is useful when debugging
1327 kernel boot problems.
1328
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329 lp=0 [LP] Specify parallel ports to use, e.g,
1330 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1331 lp=reset first parallel port). 'lp=0' disables the
1332 lp=auto printer driver. 'lp=reset' (which can be
1333 specified in addition to the ports) causes
1334 attached printers to be reset. Using
1335 lp=port1,port2,... specifies the parallel ports
1336 to associate lp devices with, starting with
1337 lp0. A port specification may be 'none' to skip
1338 that lp device, or a parport name such as
1339 'parport0'. Specifying 'lp=auto' instead of a
1340 port specification list means that device IDs
1341 from each port should be examined, to see if
1342 an IEEE 1284-compliant printer is attached; if
1343 so, the driver will manage that printer.
1344 See also header of drivers/char/lp.c.
1345
1346 lpj=n [KNL]
1347 Sets loops_per_jiffy to given constant, thus avoiding
1348 time-consuming boot-time autodetection (up to 250 ms per
1349 CPU). 0 enables autodetection (default). To determine
1350 the correct value for your kernel, boot with normal
1351 autodetection and see what value is printed. Note that
1352 on SMP systems the preset will be applied to all CPUs,
1353 which is likely to cause problems if your CPUs need
1354 significantly divergent settings. An incorrect value
1355 will cause delays in the kernel to be wrong, leading to
1356 unpredictable I/O errors and other breakage. Although
1357 unlikely, in the extreme case this might damage your
1358 hardware.
1359
1360 ltpc= [NET]
1361 Format: <io>,<irq>,<dma>
1362
Randy Dunlap16290242011-08-13 12:34:52 -07001363 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001364 (machvec) in a generic kernel.
1365 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Wu Zhangjin3209e702009-07-02 23:27:12 +08001367 machtype= [Loongson] Share the same kernel image file between different
1368 yeeloong laptop.
1369 Example: machtype=lemote-yeeloong-2f-7inch
1370
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001371 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1372 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373
1374 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001375 should make use of. maxcpus=n : n >= 0 limits the
1376 kernel to using 'n' processors. n=0 is a special case,
1377 it is equivalent to "nosmp", which also disables
1378 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
Kay Sieversd134b002011-07-31 22:08:04 +02001380 max_loop= [LOOP] The number of loop block devices that get
1381 (loop.max_loop) unconditionally pre-created at init time. The default
1382 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1383 of statically allocating a predefined number, loop
1384 devices can be requested on-demand with the
1385 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001386
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 mcatest= [IA-64]
1388
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001389 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
Uwe Hermann71cced62008-10-20 09:32:21 -07001391 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001392
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 md= [HW] RAID subsystems devices and level
1394 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001395
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 mdacon= [MDA]
1397 Format: <first>,<last>
1398 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001399
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1401 Amount of memory to be used when the kernel is not able
1402 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001403 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 address space collisions. Without memmap= PCI devices
1405 could be placed at addresses belonging to unused RAM.
1406
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001407 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 memory.
1409
Paul Mundt6902aa82008-09-21 17:14:42 +09001410 memchunk=nn[KMG]
1411 [KNL,SH] Allow user to override the default size for
1412 per-device physically contiguous DMA buffers.
1413
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301414 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 E820 memory map, as specified by the user.
1416 Such memmap=exactmap lines can be constructed based on
1417 BIOS output or other requirements. See the memmap=nn@ss
1418 option description.
1419
1420 memmap=nn[KMG]@ss[KMG]
1421 [KNL] Force usage of a specific region of memory
1422 Region of memory to be used, from ss to ss+nn.
1423
1424 memmap=nn[KMG]#ss[KMG]
1425 [KNL,ACPI] Mark specific memory as ACPI data.
1426 Region of memory to be used, from ss to ss+nn.
1427
1428 memmap=nn[KMG]$ss[KMG]
1429 [KNL,ACPI] Mark specific memory as reserved.
1430 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001431 Example: Exclude memory from 0x18690000-0x1869ffff
1432 memmap=64K$0x18690000
1433 or
1434 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001436 memory_corruption_check=0/1 [X86]
1437 Some BIOSes seem to corrupt the first 64k of
1438 memory when doing things like suspend/resume.
1439 Setting this option will scan the memory
1440 looking for corruption. Enabling this will
1441 both detect corruption and prevent the kernel
1442 from using the memory being corrupted.
1443 However, its intended as a diagnostic tool; if
1444 repeatable BIOS-originated corruption always
1445 affects the same memory, you can use memmap=
1446 to prevent the kernel from using that memory.
1447
1448 memory_corruption_check_size=size [X86]
1449 By default it checks for corruption in the low
1450 64k, making this memory unavailable for normal
1451 use. Use this parameter to scan for
1452 corruption in more or less memory.
1453
1454 memory_corruption_check_period=seconds [X86]
1455 By default it checks for corruption every 60
1456 seconds. Use this parameter to check at some
1457 other rate. 0 disables periodic checking.
1458
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001459 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001460 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001461 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001462 Specifies the number of memtest passes to be
1463 performed. Each pass selects another test
1464 pattern from a given set of patterns. Memtest
1465 fills the memory with this pattern, validates
1466 memory contents and reserves bad memory
1467 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001468
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469 meye.*= [HW] Set MotionEye Camera parameters
1470 See Documentation/video4linux/meye.txt.
1471
Andres Salomon8f368812007-10-12 23:04:06 +02001472 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1473 Multi-Function General Purpose Timers on AMD Geode
1474 platforms.
1475
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001476 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1477 the BIOS has incorrectly applied a workaround. TinyBIOS
1478 version 0.98 is known to be affected, 0.99 fixes the
1479 problem by letting the user disable the workaround.
1480
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 mga= [HW,DRM]
1482
Randy Dunlap1c207f92008-11-19 15:36:16 -08001483 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1484 physical address is ignored.
1485
Michel Pollet39f45d72009-05-20 11:10:31 +01001486 mini2440= [ARM,HW,KNL]
1487 Format:[0..2][b][c][t]
1488 Default: "0tb"
1489 MINI2440 configuration specification:
1490 0 - The attached screen is the 3.5" TFT
1491 1 - The attached screen is the 7" TFT
1492 2 - The VGA Shield is attached (1024x768)
1493 Leaving out the screen size parameter will not load
1494 the TFT driver, and the framebuffer will be left
1495 unconfigured.
1496 b - Enable backlight. The TFT backlight pin will be
1497 linked to the kernel VESA blanking code and a GPIO
1498 LED. This parameter is not necessary when using the
1499 VGA shield.
1500 c - Enable the s3c camera interface.
1501 t - Reserved for enabling touchscreen support. The
1502 touchscreen support is not enabled in the mainstream
1503 kernel as of 2.6.30, a preliminary port can be found
1504 in the "bleeding edge" mini2440 support kernel at
1505 http://repo.or.cz/w/linux-2.6/mini2440.git
1506
Mel Gorman6b74ab92008-07-23 21:26:49 -07001507 mminit_loglevel=
1508 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1509 parameter allows control of the logging verbosity for
1510 the additional memory initialisation checks. A value
1511 of 0 disables mminit logging and a level of 4 will
1512 log everything. Information is printed at KERN_DEBUG
1513 so loglevel=8 may also need to be specified.
1514
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 mousedev.tap_time=
1516 [MOUSE] Maximum time between finger touching and
1517 leaving touchpad surface for touch to be considered
1518 a tap and be reported as a left button click (for
1519 touchpads working in absolute mode only).
1520 Format: <msecs>
1521 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1522 reporting absolute coordinates, such as tablets
1523 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1524 reporting absolute coordinates, such as tablets
1525
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301526 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001527 is similar to kernelcore except it specifies the
1528 amount of memory used for migratable allocations.
1529 If both kernelcore and movablecore is specified,
1530 then kernelcore will be at *least* the specified
1531 value but may be more. If movablecore on its own
1532 is specified, the administrator must be careful
1533 that the amount of memory usable for all allocations
1534 is not too small.
1535
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 MTD_Partition= [MTD]
1537 Format: <name>,<region-number>,<size>,<offset>
1538
Randy Dunlapa9913042005-10-23 12:57:11 -07001539 MTD_Region= [MTD] Format:
1540 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541
1542 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001543 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001545 multitce=off [PPC] This parameter disables the use of the pSeries
1546 firmware feature for updating multiple TCE entries
1547 at a time.
1548
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001549 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1550
1551 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1552
1553 boundary - index of last SLC block on Flex-OneNAND.
1554 The remaining blocks are configured as MLC blocks.
1555 lock - Configure if Flex-OneNAND boundary should be locked.
1556 Once locked, the boundary cannot be changed.
1557 1 indicates lock status, 0 indicates unlock status.
1558
Ben Dooks9db829f2008-07-03 11:24:29 +01001559 mtdset= [ARM]
1560 ARM/S3C2412 JIVE boot control
1561
1562 See arch/arm/mach-s3c2412/mach-jive.c
1563
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001565 [HW] Make the MicroTouch USB driver use raw coordinates
1566 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001568 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001569 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001570 that could hold holes aka. UC entries.
1571
1572 mtrr_gran_size=nn[KMG] [X86]
1573 Used for mtrr cleanup. It is granularity of mtrr block.
1574 Default is 1.
1575 Large value could prevent small alignment from
1576 using up MTRRs.
1577
1578 mtrr_spare_reg_nr=n [X86]
1579 Format: <integer>
1580 Range: 0,7 : spare reg number
1581 Default : 1
1582 Used for mtrr cleanup. It is spare mtrr entries number.
1583 Set to 2 or more if your graphical card needs more.
1584
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1586
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 netdev= [NET] Network devices parameters
1588 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1589 Note that mem_start is often overloaded to mean
1590 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001591 This usage is only documented in each driver source
1592 file if at all.
1593
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001594 nf_conntrack.acct=
1595 [NETFILTER] Enable connection tracking flow accounting
1596 0 to disable accounting
1597 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001598 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001599
Chuck Lever306a0752010-09-17 10:54:37 -04001600 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001601 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
1603 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001604 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605
Chuck Lever306a0752010-09-17 10:54:37 -04001606 nfsrootdebug [NFS] enable nfsroot debugging messages.
1607 See Documentation/filesystems/nfs/nfsroot.txt.
1608
Trond Myklebusta72b4422006-01-03 09:55:41 +01001609 nfs.callback_tcpport=
1610 [NFS] set the TCP port on which the NFSv4 callback
1611 channel should listen.
1612
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001613 nfs.cache_getent=
1614 [NFS] sets the pathname to the program which is used
1615 to update the NFS client cache entries.
1616
1617 nfs.cache_getent_timeout=
1618 [NFS] sets the timeout after which an attempt to
1619 update a cache entry is deemed to have failed.
1620
Trond Myklebust58df0952006-01-03 09:55:57 +01001621 nfs.idmap_cache_timeout=
1622 [NFS] set the maximum lifetime for idmapper cache
1623 entries.
1624
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001625 nfs.enable_ino64=
1626 [NFS] enable 64-bit inode numbers.
1627 If zero, the NFS client will fake up a 32-bit inode
1628 number for the readdir() and stat() syscalls instead
1629 of returning the full 64-bit number.
1630 The default is to return 64-bit inode numbers.
1631
Trond Myklebustb064eca22011-02-22 15:44:32 -08001632 nfs.nfs4_disable_idmapping=
1633 [NFSv4] When set, this option disables the NFSv4
1634 idmapper on the client, but only if the mount
1635 is using the 'sec=sys' security flavour. This may
1636 make migration from legacy NFSv2/v3 systems easier
1637 provided that the server has the appropriate support.
1638 The default is to always enable NFSv4 idmapping.
1639
Paul Mundt1e1030d2009-09-01 17:38:32 +09001640 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001641 when a NMI is triggered.
1642 Format: [state][,regs][,debounce][,die]
1643
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301644 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001645 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001646 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001647 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001648 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001649 timeout occurs (or 'nopanic' to override the opposite
1650 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001651 This is useful when you use a panic=... timeout and
1652 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653
Anton Vorontsovbff38772009-07-08 11:10:56 -07001654 netpoll.carrier_timeout=
1655 [NET] Specifies amount of time (in seconds) that
1656 netpoll should wait for a carrier. By default netpoll
1657 waits 4 seconds.
1658
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001659 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 emulation library even if a 387 maths coprocessor
1661 is present.
1662
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001663 no_console_suspend
1664 [HW] Never suspend the console
1665 Disable suspending of consoles during suspend and
1666 hibernate operations. Once disabled, debugging
1667 messages can reach various consoles while the rest
1668 of the system is being put to sleep (ie, while
1669 debugging driver suspend/resume hooks). This may
1670 not work reliably with all consoles, but is known
1671 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07001672 To facilitate more flexible debugging, we also add
1673 console_suspend, a printk module parameter to control
1674 it. Users could use console_suspend (usually
1675 /sys/module/printk/parameters/console_suspend) to
1676 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001677
Christoph Lameterc1aee212007-05-31 00:40:47 -07001678 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1679 caches in the slab allocator. Saves per-node memory,
1680 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001681
Randy Dunlapa9913042005-10-23 12:57:11 -07001682 noalign [KNL,ARM]
1683
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684 noapic [SMP,APIC] Tells the kernel to not make use of any
1685 IOAPICs that may be present in the system.
1686
Mike Galbraith5091faa2010-11-30 14:18:03 +01001687 noautogroup Disable scheduler automatic task group creation.
1688
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 nobats [PPC] Do not use BATs for mapping kernel lowmem
1690 on "Classic" PPC cores.
1691
1692 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001693
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001694 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1695
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001696 nodelayacct [KNL] Disable per-task delay accounting
1697
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1699
Paul Mundt6902aa82008-09-21 17:14:42 +09001700 nodsp [SH] Disable hardware DSP at boot time.
1701
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301702 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 noexec [IA-64]
1705
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301706 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001707 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001709 noexec=off: disable non-executable mappings
1710
Fenghua Yude5397a2011-05-11 16:51:05 -07001711 nosmep [X86]
1712 Disable SMEP (Supervisor Mode Execution Protection)
1713 even if it is supported by processor.
1714
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001715 noexec32 [X86-64]
1716 This affects only 32-bit executables.
1717 noexec32=on: enable non-executable mappings (default)
1718 read doesn't imply executable mappings
1719 noexec32=off: disable non-executable mappings
1720 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
Paul Mundt6902aa82008-09-21 17:14:42 +09001722 nofpu [SH] Disable hardware FPU at boot time.
1723
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001724 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001725 register save and restore. The kernel will only save
1726 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727
Suresh Siddha0c752a92009-05-22 12:17:45 -07001728 noxsave [BUGS=X86] Disables x86 extended register state save
1729 and restore using xsave. The kernel will fallback to
1730 enabling legacy floating-point and sse state.
1731
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001732 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1733 wfi(ARM) instruction doesn't work correctly and not to
1734 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001735
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001736 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 instruction doesn't work correctly and not to
1738 use it.
1739
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001740 no_file_caps Tells the kernel not to honor file capabilities. The
1741 only way then for a file to be executed with privilege
1742 is to be setuid root or executed by root.
1743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 nohalt [IA-64] Tells the kernel not to use the power saving
1745 function PAL_HALT_LIGHT when idle. This increases
1746 power-consumption. On the positive side, it reduces
1747 interrupt wake-up latency, which may improve performance
1748 in certain environments such as networked servers or
1749 real-time systems.
1750
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001751 nohz= [KNL] Boottime enable/disable dynamic ticks
1752 Valid arguments: on, off
1753 Default: on
1754
Paul Mundteeee7852009-04-02 12:31:16 +09001755 noiotrap [SH] Disables trapped I/O port accesses.
1756
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001757 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 disable unhandled interrupt sources.
1759
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301760 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001761 broken timer IRQ sources.
1762
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 noisapnp [ISAPNP] Disables ISA PnP code.
1764
1765 noinitrd [RAM] Tells the kernel not to load any configured
1766 initial RAM disk.
1767
Weidong Han03ea8152009-04-17 16:42:15 +08001768 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1769 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001770 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001771
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772 nointroute [IA-64]
1773
Randy Dunlap16290242011-08-13 12:34:52 -07001774 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07001775
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001776 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1777
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001778 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1779 fault handling.
1780
Glauber Costad910f5c2011-07-11 15:28:19 -04001781 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1782 steal time is computed, but won't influence scheduler
1783 behaviour
1784
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001785 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001787 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001788
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 noltlbs [PPC] Do not use large page/tlb entries for kernel
1790 lowmem mapping on PPC40x.
1791
Horms312f1f02006-02-22 09:57:55 +09001792 nomca [IA-64] Disable machine check abort handling
1793
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001794 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001795
Andres Salomon83d73842007-10-12 23:04:06 +02001796 nomfgpt [X86-32] Disable Multi-Function General Purpose
1797 Timer usage (for AMD Geode machines).
1798
Jiri Kosina016ddd92010-01-18 17:05:40 +01001799 nopat [X86] Disable PAT (page attribute table extension of
1800 pagetables) support.
1801
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001802 norandmaps Don't use address space randomization. Equivalent to
1803 echo 0 > /proc/sys/kernel/randomize_va_space
1804
Jiri Kosinabbff2162010-08-11 18:34:09 +02001805 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001806
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001807 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001808 with UP alternatives
1809
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 noresidual [PPC] Don't use residual data on PReP machines.
1811
H. Peter Anvin49d859d2011-07-31 14:02:19 -07001812 nordrand [X86] Disable the direct use of the RDRAND
1813 instruction even if it is supported by the
1814 processor. RDRAND is still available to user
1815 space applications.
1816
Randy Dunlapa9913042005-10-23 12:57:11 -07001817 noresume [SWSUSP] Disables resume and restores original swap
1818 space.
1819
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820 no-scroll [VGA] Disables scrollback.
1821 This is required for the Braillex ib80-piezo Braille
1822 reader made by F.H. Papenmeier (Germany).
1823
1824 nosbagart [IA-64]
1825
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001826 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001827
Len Brown61ec7562007-08-16 03:34:22 -04001828 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1829 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830
Dave Jones97842212007-07-15 23:41:05 -07001831 nosoftlockup [KNL] Disable the soft-lockup detector.
1832
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 nosync [HW,M68K] Disables sync negotiation for all devices.
1834
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001835 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836
1837 nousb [USB] Disable the USB subsystem
1838
Ben Hutchings55142372011-01-02 23:02:42 +00001839 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001840
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001842
Weidong Han2b2fd872009-04-17 16:42:12 +08001843 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1844
Randy Dunlap16290242011-08-13 12:34:52 -07001845 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07001846 purges which is reported from either PAL_VM_SUMMARY or
1847 SAL PALO.
1848
Yinghai Lu2b633e32010-02-10 01:20:37 -08001849 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1850 could support. nr_cpus=n : n >= 1 limits the kernel to
1851 supporting 'n' processors. Later in runtime you can not
1852 use hotplug cpu feature to put more cpu back to online.
1853 just like you compile the kernel NR_CPUS=n
1854
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001855 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1856
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001857 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1858 one of ['zone', 'node', 'default'] can be specified
1859 This can be set from sysctl after boot.
1860 See Documentation/sysctl/vm.txt for details.
1861
Randy Dunlap7c4be252009-01-06 14:42:44 -08001862 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1863 See Documentation/debugging-via-ohci1394.txt for more
1864 info.
1865
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001866 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1867 Rather than timing out after 20 ms if an EC
1868 command is not properly ACKed, override the length
1869 of the timeout. We have interrupts disabled while
1870 waiting for the ACK, so if this is set too high
1871 interrupts *may* be lost!
1872
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001873 omap_mux= [OMAP] Override bootloader pin multiplexing.
1874 Format: <mux_mode0.mode_name=value>...
1875 For example, to override I2C bus2:
1876 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1877
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 oprofile.timer= [HW]
1879 Use timer interrupt instead of performance counters
1880
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001881 oprofile.cpu_type= Force an oprofile cpu type
1882 This might be useful if you have an older oprofile
1883 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001884 Format: { arch_perfmon }
1885 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001886 perfmon on Intel CPUs instead of the
1887 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001888
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001889 oops=panic Always panic on oopses. Default is to just kill the
1890 process, but there is a small probability of
1891 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07001892 This will also cause panics on machine check exceptions.
1893 Useful together with panic=30 to trigger a reboot.
1894
Randy Dunlapbcfde332010-06-07 17:10:38 -07001895 OSS [HW,OSS]
1896 See Documentation/sound/oss/oss-parameters.txt
1897
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001898 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07001899 timeout > 0: seconds before rebooting
1900 timeout = 0: wait forever
1901 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902 Format: <timeout>
1903
1904 parkbd.port= [HW] Parallel port number the keyboard adapter is
1905 connected to, default is 0.
1906 Format: <parport#>
1907 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1908 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001909 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910
Randy Dunlapa9913042005-10-23 12:57:11 -07001911 parport= [HW,PPT] Specify parallel ports. 0 disables.
1912 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1913 Use 'auto' to force the driver to use any
1914 IRQ/DMA settings detected (the default is to
1915 ignore detected IRQ/DMA settings because of
1916 possible conflicts). You can specify the base
1917 address, IRQ, and DMA settings; IRQ and DMA
1918 should be numbers, or 'auto' (for using detected
1919 settings on that particular port), or 'nofifo'
1920 (to avoid using a FIFO even if it is detected).
1921 Parallel ports are assigned in the order they
1922 are specified on the command line, starting
1923 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924
Randy Dunlapa9913042005-10-23 12:57:11 -07001925 parport_init_mode= [HW,PPT]
1926 Configure VIA parallel port to operate in
1927 a specific mode. This is necessary on Pegasos
1928 computer where firmware has no options for setting
1929 up parallel port mode and sets it to spp.
1930 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931 Format: [spp|ps2|epp|ecp|ecpepp]
1932
Andrew Mortondd287792006-03-23 03:00:57 -08001933 pause_on_oops=
1934 Halt all CPUs after the first oops has been printed for
1935 the specified number of seconds. This is to be used if
1936 your oopses keep scrolling off the screen.
1937
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 pcbit= [HW,ISDN]
1939
1940 pcd. [PARIDE]
1941 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001942 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943
Randy Dunlapa9913042005-10-23 12:57:11 -07001944 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001945 earlydump [X86] dump PCI config space before the kernel
1946 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001947 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001948 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001949 the hardware directly. Use this if your machine
1950 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001951 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001952 hardware access methods are allowed. Use this
1953 if you experience crashes upon bootup and you
1954 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001955 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001956 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001957 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001958 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001959 noaer [PCIE] If the PCIEAER kernel config parameter is
1960 enabled, this kernel boot option can be used to
1961 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001962 nodomains [PCI] Disable support for multiple PCI
1963 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301964 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001965 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001966 check_enable_amd_mmconf [X86] check for and enable
1967 properly configured MMIO access to PCI
1968 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001969 nomsi [MSI] If the PCI_MSI kernel config parameter is
1970 enabled, this kernel boot option can be used to
1971 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001972 noioapicquirk [APIC] Disable all boot interrupt quirks.
1973 Safety option to keep boot IRQs enabled. This
1974 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001975 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1976 primary IO-APIC for bridges that cannot disable
1977 boot IRQs. This fixes a source of spurious IRQs
1978 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001979 noioapicreroute [APIC] Disable workaround that uses the
1980 boot IRQ equivalent of an IRQ that connects to
1981 a chipset where boot IRQs cannot be disabled.
1982 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001983 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001984 routing table. These calls are known to be buggy
1985 on several machines and they hang the machine
1986 when used, but on other computers it's the only
1987 way to get the interrupt routing table. Try
1988 this option if the kernel is unable to allocate
1989 IRQs or discover secondary PCI buses on your
1990 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001991 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001992 Use with caution as certain devices share
1993 address decoders between ROMs and other
1994 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001995 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001996 expansion ROMs that do not already have
1997 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07001998 nobar [X86] Do not assign address space to the
1999 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002000 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002001 assigned automatically to PCI devices. You can
2002 make the kernel exclude IRQs of your ISA cards
2003 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002004 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002005 of the PIRQ table (normally generated
2006 by the BIOS) if it is outside the
2007 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002008 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002009 useful if the kernel is unable to find your
2010 secondary buses and you want to tell it
2011 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002012 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002013 numbers ourselves, overriding
2014 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002015 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002016 in the BIOS $PIR table. This is needed on
2017 some systems with broken BIOSes, notably
2018 some HP Pavilion N5400 and Omnibook XE3
2019 notebooks. This will have no effect if ACPI
2020 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002021 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002022 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002023 use_crs [X86] Use PCI host bridge window information
2024 from ACPI. On BIOSes from 2008 or later, this
2025 is enabled by default. If you need to use this,
2026 please report a bug.
2027 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2028 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002029 routeirq Do IRQ routing for all PCI devices.
2030 This is normally done in pci_enable_device(),
2031 so this option is a temporary workaround
2032 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002033 skip_isa_align [X86] do not align io start addr, so can
2034 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002035 firmware [ARM] Do not re-enumerate the bus but instead
2036 just use the configuration from the
2037 bootloader. This is currently used on
2038 IXP2000 systems where the bus has to be
2039 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002040 noearly [X86] Don't do any early type 1 scanning.
2041 This might help on some broken boards which
2042 machine check when some devices' config space
2043 is read. But various workarounds are disabled
2044 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002045 bfsort Sort PCI devices into breadth-first order.
2046 This sorting is done to get a device
2047 order compatible with older (<= 2.4) kernels.
2048 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002049 cbiosize=nn[KMG] The fixed amount of bus space which is
2050 reserved for the CardBus bridge's IO window.
2051 The default value is 256 bytes.
2052 cbmemsize=nn[KMG] The fixed amount of bus space which is
2053 reserved for the CardBus bridge's memory
2054 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002055 resource_alignment=
2056 Format:
2057 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2058 Specifies alignment and device to reassign
2059 aligned memory resources.
2060 If <order of align> is not specified,
2061 PAGE_SIZE is used as alignment.
2062 PCI-PCI bridge can be specified, if resource
2063 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002064 ecrc= Enable/disable PCIe ECRC (transaction layer
2065 end-to-end CRC checking).
2066 bios: Use BIOS/firmware settings. This is the
2067 the default.
2068 off: Turn ECRC off
2069 on: Turn ECRC on.
Ram Paif483d392011-07-07 11:19:10 -07002070 realloc reallocate PCI resources if allocations done by BIOS
2071 are erroneous.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002072
Chuck Ebberte5665a42008-09-24 20:40:34 -04002073 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2074 Management.
2075 off Disable ASPM.
2076 force Enable ASPM even on devices that claim not to support it.
2077 WARNING: Forcing ASPM on may cause system lockups.
2078
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002079 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002080 auto Ask the BIOS whether or not to use native PCIe services
2081 associated with PCIe ports (PME, hot-plug, AER). Use
2082 them only if that is allowed by the BIOS.
2083 native Use native PCIe services associated with PCIe ports
2084 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002085 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2086 ports driver.
2087
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002088 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002089 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002090 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002091
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 pcmv= [HW,PCMCIA] BadgePAD 4
2093
2094 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002095 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096
2097 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2098 boot time.
2099 Format: { 0 | 1 }
2100 See arch/parisc/kernel/pdc_chassis.c
2101
Tejun Heof58dc012009-08-14 15:00:50 +09002102 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002103 Currently supported values are "embed" and "page".
2104 Archs may support subset or none of the selections.
2105 See comments in mm/percpu.c for details on each
2106 allocator. This parameter is primarily for debugging
2107 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002108
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002110 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111
2112 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002113 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114
2115 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002116 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117
2118 plip= [PPT,NET] Parallel port network link
2119 Format: { parport<nr> | timid | 0 }
2120 See also Documentation/parport.txt.
2121
Randy Dunlap16290242011-08-13 12:34:52 -07002122 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002123 Override pmtimer IOPort with a hex value.
2124 e.g. pmtmr=0x508
2125
Bjorn Helgaas96242112011-08-11 12:14:05 -06002126 pnp.debug=1 [PNP]
2127 Enable PNP debug messages (depends on the
2128 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2129 via /sys/module/pnp/parameters/debug. We always show
2130 current resource usage; turning this on also shows
2131 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002132
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 pnpacpi= [ACPI]
2134 { off }
2135
2136 pnpbios= [ISAPNP]
2137 { on | off | curr | res | no-curr | no-res }
2138
2139 pnp_reserve_irq=
2140 [ISAPNP] Exclude IRQs for the autoconfiguration
2141
2142 pnp_reserve_dma=
2143 [ISAPNP] Exclude DMAs for the autoconfiguration
2144
2145 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002146 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147
2148 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002149 [ISAPNP] Exclude memory regions for the
2150 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002151 Ranges are in pairs (memory base and size).
2152
Randy Dunlap4af94f32009-04-17 18:30:28 -07002153 ports= [IP_VS_FTP] IPVS ftp helper module
2154 Default is 21.
2155 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2156 may be specified.
2157 Format: <port>,<port>....
2158
Ingo Molnar45807a12007-07-15 23:40:10 -07002159 print-fatal-signals=
2160 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002161
2162 If enabled, warn about various signal handling
2163 related application anomalies: too many signals,
2164 too many POSIX.1 timers, fatal signals causing a
2165 coredump - etc.
2166
2167 If you hit the warning due to signal overflow,
2168 you might want to try "ulimit -i unlimited".
2169
Ingo Molnar45807a12007-07-15 23:40:10 -07002170 default: off.
2171
Randy Dunlape84845c2007-07-15 23:40:25 -07002172 printk.time= Show timing data prefixed to each printk message line
2173 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2174
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002175 processor.max_cstate= [HW,ACPI]
2176 Limit processor to maximum C-state
2177 max_cstate=9 overrides any DMI blacklist limit.
2178
2179 processor.nocst [HW,ACPI]
2180 Ignore the _CST method to determine C-states,
2181 instead using the legacy FADT method
2182
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002184 Format: [schedule,]<number>
2185 Param: "schedule" - profile schedule points.
2186 Param: <number> - step/bucket size as a power of 2 for
2187 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002188 Param: "sleep" - profile D-state sleeping (millisecs).
2189 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002190 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2193 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002194 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195
Randy Dunlapa9913042005-10-23 12:57:11 -07002196 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2197 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2199 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002200 psmouse.resetafter= [HW,MOUSE]
2201 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202 (0 = never).
2203 psmouse.resolution=
2204 [HW,MOUSE] Set desired mouse resolution, in dpi.
2205 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002206 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 0 = disabled, 1 = enabled (default).
2208
Matthew Garrettdee28e72011-07-21 16:57:55 -04002209 pstore.backend= Specify the name of the pstore backend to use
2210
Linus Torvalds1da177e2005-04-16 15:20:36 -07002211 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002212 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213
Kay Sieversdc8c8582007-08-15 12:25:38 +02002214 pty.legacy_count=
2215 [KNL] Number of legacy pty's. Overwrites compiled-in
2216 default number.
2217
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002218 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002219
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 r128= [HW,DRM]
2221
2222 raid= [HW,RAID]
2223 See Documentation/md.txt.
2224
Randy Dunlapa9913042005-10-23 12:57:11 -07002225 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002226 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002227
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002229 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002231 rcupdate.blimit= [KNL,BOOT]
2232 Set maximum number of finished RCU callbacks to process
2233 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002234
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002235 rcupdate.qhimark= [KNL,BOOT]
2236 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002237 RCU callbacks over which batch limiting is disabled.
2238
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002239 rcupdate.qlowmark= [KNL,BOOT]
2240 Set threshold of queued RCU callbacks below which
2241 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002242
Olof Johanssonffdfc402005-09-06 15:17:19 -07002243 rdinit= [KNL]
2244 Format: <full_path>
2245 Run specified binary instead of /init from the ramdisk,
2246 used for early userspace startup. See initrd.
2247
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002248 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002250 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251
Paul Jackson46b6d942008-07-04 10:00:09 -07002252 relax_domain_level=
2253 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002254 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002255
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2257
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002258 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002259 Format: nn[KMG]
2260 Reserves a hole at the top of the kernel virtual
2261 address space.
2262
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002263 reservelow= [X86]
2264 Format: nn[K]
2265 Set the amount of memory to reserve for BIOS at
2266 the bottom of the address space.
2267
Vivek Goyal7e962872006-09-27 01:50:44 -07002268 reset_devices [KNL] Force drivers to reset the underlying device
2269 during initialization.
2270
Randy Dunlapa9913042005-10-23 12:57:11 -07002271 resume= [SWSUSP]
2272 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002274 resume_offset= [SWSUSP]
2275 Specify the offset from the beginning of the partition
2276 given by "resume=" at which the swap header is located,
2277 in <PAGE_SIZE> units (needed only for swap files).
2278 See Documentation/power/swsusp-and-swap-files.txt
2279
Barry Songf126f732011-10-10 23:38:41 +02002280 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2281 read the resume files
2282
Barry Song6f8d7022011-10-06 20:34:46 +02002283 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2284 Useful for devices that are detected asynchronously
2285 (e.g. USB and MMC devices).
2286
Bojan Smojverf996fc92010-09-09 23:06:23 +02002287 hibernate= [HIBERNATION]
2288 noresume Don't check if there's a hibernation image
2289 present during boot.
2290 nocompress Don't compress/decompress hibernation images.
2291
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002292 retain_initrd [RAM] Keep initrd memory after extraction
2293
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 rhash_entries= [KNL,NET]
2295 Set number of hash buckets for route cache
2296
2297 riscom8= [HW,SERIAL]
2298 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2299
2300 ro [KNL] Mount root device read-only on boot
2301
2302 root= [KNL] Root filesystem
Will Drewryf2d34fd2011-08-03 16:21:08 -07002303 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304
2305 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2306 mount the root filesystem
2307
2308 rootflags= [KNL] Set root filesystem mount option string
2309
2310 rootfstype= [KNL] Set root filesystem type
2311
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002312 rootwait [KNL] Wait (indefinitely) for root device to show up.
2313 Useful for devices that are detected asynchronously
2314 (e.g. USB and MMC devices).
2315
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 rw [KNL] Mount root device read-write on boot
2317
2318 S [KNL] Run init in single mode
2319
2320 sa1100ir [NET]
2321 See drivers/net/irda/sa1100_ir.c.
2322
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002324
Mike Travisf6630112009-11-17 18:22:15 -06002325 sched_debug [KNL] Enables verbose scheduler debug messages.
2326
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002327 security= [SECURITY] Choose a security module to enable at boot.
2328 If this boot parameter is not specified, only the first
2329 security module asking for security registration will be
2330 loaded. An invalid security module name will be treated
2331 as if no module has been chosen.
2332
2333 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334 Format: { "0" | "1" }
2335 See security/selinux/Kconfig help text.
2336 0 -- disable.
2337 1 -- enable.
2338 Default value is set via kernel config option.
2339 If enabled at boot time, /selinux/disable can be used
2340 later to disable prior to initial policy load.
2341
John Johansenc1c124e2010-07-29 14:48:09 -07002342 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2343 Format: { "0" | "1" }
2344 See security/apparmor/Kconfig help text
2345 0 -- disable.
2346 1 -- enable.
2347 Default value is set via kernel config option.
2348
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002349 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 shapers= [NET]
2352 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002353
Yinghai Lub05f78f2008-08-22 01:32:50 -07002354 show_msr= [x86] show boot-time MSR settings
2355 Format: { <integer> }
2356 Show boot-time (BIOS-initialized) MSR settings.
2357 The parameter means the number of CPUs to show,
2358 for example 1 means boot CPU only.
2359
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360 simeth= [IA-64]
2361 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002362
Linus Torvalds1da177e2005-04-16 15:20:36 -07002363 slram= [HW,MTD]
2364
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002365 slub_debug[=options[,slabs]] [MM, SLUB]
2366 Enabling slub_debug allows one to determine the
2367 culprit if slab objects become corrupted. Enabling
2368 slub_debug can create guard zones around objects and
2369 may poison objects when not in use. Also tracks the
2370 last alloc / free. For more information see
2371 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002372
2373 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002374 Determines the maximum allowed order for slabs.
2375 A high setting may cause OOMs due to memory
2376 fragmentation. For more information see
2377 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002378
2379 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002380 The minimum number of objects per slab. SLUB will
2381 increase the slab order up to slub_max_order to
2382 generate a sufficiently large slab able to contain
2383 the number of objects indicated. The higher the number
2384 of objects the smaller the overhead of tracking slabs
2385 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002386 For more information see Documentation/vm/slub.txt.
2387
2388 slub_min_order= [MM, SLUB]
2389 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002390 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002391 For more information see Documentation/vm/slub.txt.
2392
2393 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002394 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002395 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002396 allocs to different slabs. Debug options disable
2397 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002398 For more information see Documentation/vm/slub.txt.
2399
Linus Torvalds1da177e2005-04-16 15:20:36 -07002400 smart2= [HW]
2401 Format: <io1>[,<io2>[,...,<io8>]]
2402
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002403 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002404 attempt to substitute SMP alternatives once at boot.
2405
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002406 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2407 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2408 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2409 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2410 smsc-ircc2.ircc_irq= [HW] IRQ line
2411 smsc-ircc2.ircc_dma= [HW] DMA channel
2412 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2413 0: Toshiba Satellite 1800 (GP data pin select)
2414 1: Fast pin select (default)
2415 2: ATC IRMode
2416
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002417 softlockup_panic=
2418 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002419 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002420
Linus Torvalds1da177e2005-04-16 15:20:36 -07002421 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02002422 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423
2424 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002425 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426
2427 spia_io_base= [HW,MTD]
2428 spia_fio_base=
2429 spia_pedr=
2430 spia_peddr=
2431
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002432 stacktrace [FTRACE]
2433 Enabled the stack tracer on boot up.
2434
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 sti= [PARISC,HW]
2436 Format: <num>
2437 Set the STI (builtin display/keyboard on the HP-PARISC
2438 machines) console (graphic card) which should be used
2439 as the initial boot-console.
2440 See also comment in drivers/video/console/sticore.c.
2441
2442 sti_font= [HW]
2443 See comment in drivers/video/console/sticore.c.
2444
2445 stifb= [HW]
2446 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2447
Trond Myklebustcbf11072009-08-09 15:06:19 -04002448 sunrpc.min_resvport=
2449 sunrpc.max_resvport=
2450 [NFS,SUNRPC]
2451 SunRPC servers often require that client requests
2452 originate from a privileged port (i.e. a port in the
2453 range 0 < portnr < 1024).
2454 An administrator who wishes to reserve some of these
2455 ports for other uses may adjust the range that the
2456 kernel's sunrpc client considers to be privileged
2457 using these two parameters to set the minimum and
2458 maximum port values.
2459
Greg Banks42a7fc42007-03-06 01:42:23 -08002460 sunrpc.pool_mode=
2461 [NFS]
2462 Control how the NFS server code allocates CPUs to
2463 service thread pools. Depending on how many NICs
2464 you have and where their interrupts are bound, this
2465 option will affect which CPUs will do NFS serving.
2466 Note: this parameter cannot be changed while the
2467 NFS server is running.
2468
2469 auto the server chooses an appropriate mode
2470 automatically using heuristics
2471 global a single global pool contains all CPUs
2472 percpu one pool for each CPU
2473 pernode one pool for each NUMA node (equivalent
2474 to global on non-NUMA machines)
2475
Trond Myklebustcbf11072009-08-09 15:06:19 -04002476 sunrpc.tcp_slot_table_entries=
2477 sunrpc.udp_slot_table_entries=
2478 [NFS,SUNRPC]
2479 Sets the upper limit on the number of simultaneous
2480 RPC calls that can be sent from the client to a
2481 server. Increasing these values may allow you to
2482 improve throughput, but will also increase the
2483 amount of memory reserved for use by the client.
2484
Michal Hockoa42c3902010-11-24 12:57:08 -08002485 swapaccount[=0|1]
2486 [KNL] Enable accounting of swap in memory resource
2487 controller if no parameter or 1 is given or disable
2488 it if 0 is given (See Documentation/cgroups/memory.txt)
2489
Linus Torvalds1da177e2005-04-16 15:20:36 -07002490 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002491
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492 switches= [HW,M68k]
2493
Andi Kleene52eec12010-09-08 16:54:17 +02002494 sysfs.deprecated=0|1 [KNL]
2495 Enable/disable old style sysfs layout for old udev
2496 on older distributions. When this option is enabled
2497 very new udev will not work anymore. When this option
2498 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2499 in older udev will not work anymore.
2500 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2501 the kernel configuration.
2502
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002503 sysrq_always_enabled
2504 [KNL]
2505 Ignore sysrq setting - this boot parameter will
2506 neutralize any effect of /proc/sys/kernel/sysrq.
2507 Useful for debugging.
2508
Linus Torvalds1da177e2005-04-16 15:20:36 -07002509 tdfx= [HW,DRM]
2510
David Brownell77437fd2008-07-23 21:28:33 -07002511 test_suspend= [SUSPEND]
2512 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2513 standby suspend) as the system sleep state to briefly
2514 enter during system startup. The system is woken from
2515 this state using a wakeup-capable RTC alarm.
2516
Linus Torvalds1da177e2005-04-16 15:20:36 -07002517 thash_entries= [KNL,NET]
2518 Set number of hash buckets for TCP connection
2519
Len Brownf8707ec2007-08-12 00:12:54 -04002520 thermal.act= [HW,ACPI]
2521 -1: disable all active trip points in all thermal zones
2522 <degrees C>: override all lowest active trip points
2523
Len Brownc52a7412007-08-14 15:49:32 -04002524 thermal.crt= [HW,ACPI]
2525 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002526 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002527
Len Brownf5487142007-08-12 00:12:44 -04002528 thermal.nocrt= [HW,ACPI]
2529 Set to disable actions on ACPI thermal zone
2530 critical and hot trip points.
2531
Len Brown72b33ef2007-08-12 00:12:17 -04002532 thermal.off= [HW,ACPI]
2533 1: disable ACPI thermal control
2534
Len Browna70cdc52007-08-12 00:12:35 -04002535 thermal.psv= [HW,ACPI]
2536 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002537 <degrees C>: override all passive trip points to this
2538 value
Len Browna70cdc52007-08-12 00:12:35 -04002539
Len Brown730ff342007-08-12 00:12:26 -04002540 thermal.tzp= [HW,ACPI]
2541 Specify global default ACPI thermal zone polling rate
2542 <deci-seconds>: poll all this frequency
2543 0: no polling (default)
2544
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002545 threadirqs [KNL]
2546 Force threading of all interrupt handlers except those
2547 marked explicitely IRQF_NO_THREAD.
2548
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002549 topology= [S390]
2550 Format: {off | on}
2551 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002552 topology information if the hardware supports this.
2553 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002554 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002555 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002556
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 tp720= [HW,PS2]
2558
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002559 tpm_suspend_pcr=[HW,TPM]
2560 Format: integer pcr id
2561 Specify that at suspend time, the tpm driver
2562 should extend the specified pcr with zeros,
2563 as a workaround for some chips which fail to
2564 flush the last written pcr on TPM_SaveState.
2565 This will guarantee that all the other pcrs
2566 are saved.
2567
Li Zefan9d612be2009-06-24 17:33:15 +08002568 trace_buf_size=nn[KMG]
2569 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002570
Li Zefan020e5f82009-07-01 10:47:05 +08002571 trace_event=[event-list]
2572 [FTRACE] Set and start specified trace events in order
2573 to facilitate early boot debugging.
2574 See also Documentation/trace/events.txt
2575
john stultzd3b8f882009-08-17 16:40:47 -07002576 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002577 Format: <string>
2578 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002579 disables clocksource verification at runtime, as well
2580 as the stability checks done at bootup. Used to enable
2581 high-resolution timer mode on older hardware, and in
2582 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002583 [x86] noirqtime: Do not use TSC to do irq accounting.
2584 Used to run time disable IRQ_TIME_ACCOUNTING on any
2585 platforms where RDTSC is slow and this accounting
2586 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002587
Randy Dunlapa9913042005-10-23 12:57:11 -07002588 turbografx.map[2|3]= [HW,JOY]
2589 TurboGraFX parallel port interface
2590 Format:
2591 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002592 See also Documentation/input/joystick-parport.txt
2593
Christian Kujaub6935f82011-05-31 15:22:05 +00002594 udbg-immortal [PPC] When debugging early kernel crashes that
2595 happen after console_init() and before a proper
2596 console driver takes over, this boot options might
2597 help "seeing" what's going on.
2598
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002599 uhash_entries= [KNL,NET]
2600 Set number of hash buckets for UDP/UDP-Lite connections
2601
Alan Stern5f8364b2006-12-05 16:29:55 -05002602 uhci-hcd.ignore_oc=
2603 [USB] Ignore overcurrent events (default N).
2604 Some badly-designed motherboards generate lots of
2605 bogus events, for ports that aren't wired to
2606 anything. Set this parameter to avoid log spamming.
2607 Note that genuine overcurrent events won't be
2608 reported either.
2609
Simon Arlotte3a61b02008-07-19 23:32:54 +01002610 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002611 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01002612
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02002613 usbcore.authorized_default=
2614 [USB] Default USB device authorization:
2615 (default -1 = authorized except for wireless USB,
2616 0 = not authorized, 1 = authorized)
2617
Alan Sternb5e795f2007-02-20 15:00:53 -05002618 usbcore.autosuspend=
2619 [USB] The autosuspend time delay (in seconds) used
2620 for newly-detected USB devices (default 2). This
2621 is the time required before an idle device will be
2622 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002623 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002624
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002625 usbcore.usbfs_snoop=
2626 [USB] Set to log all usbfs traffic (default 0 = off).
2627
2628 usbcore.blinkenlights=
2629 [USB] Set to cycle leds on hubs (default 0 = off).
2630
2631 usbcore.old_scheme_first=
2632 [USB] Start with the old device initialization
2633 scheme (default 0 = off).
2634
2635 usbcore.use_both_schemes=
2636 [USB] Try the other device initialization scheme
2637 if the first one fails (default 1 = enabled).
2638
2639 usbcore.initial_descriptor_timeout=
2640 [USB] Specifies timeout for the initial 64-byte
2641 USB_REQ_GET_DESCRIPTOR request in milliseconds
2642 (default 5000 = 5.0 seconds).
2643
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 usbhid.mousepoll=
2645 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002646
Alan Sternd4f373e2008-11-10 14:07:45 -05002647 usb-storage.delay_use=
2648 [UMS] The delay in seconds before a new device is
2649 scanned for Logical Units (default 5).
2650
2651 usb-storage.quirks=
2652 [UMS] A list of quirks entries to supplement or
2653 override the built-in unusual_devs list. List
2654 entries are separated by commas. Each entry has
2655 the form VID:PID:Flags where VID and PID are Vendor
2656 and Product ID values (4-digit hex numbers) and
2657 Flags is a set of characters, each corresponding
2658 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002659 a = SANE_SENSE (collect more than 18 bytes
2660 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002661 b = BAD_SENSE (don't collect more than 18
2662 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002663 c = FIX_CAPACITY (decrease the reported
2664 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01002665 d = NO_READ_DISC_INFO (don't use
2666 READ_DISC_INFO command);
2667 e = NO_READ_CAPACITY_16 (don't use
2668 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05002669 h = CAPACITY_HEURISTICS (decrease the
2670 reported device capacity by one
2671 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002672 i = IGNORE_DEVICE (don't bind to this
2673 device);
2674 l = NOT_LOCKABLE (don't try to lock and
2675 unlock ejectable media);
2676 m = MAX_SECTORS_64 (don't transfer more
2677 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04002678 n = INITIAL_READ10 (force a retry of the
2679 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05002680 o = CAPACITY_OK (accept the capacity
2681 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002682 r = IGNORE_RESIDUE (the device reports
2683 bogus residue values);
2684 s = SINGLE_LUN (the device has only one
2685 Logical Unit);
2686 w = NO_WP_DETECT (don't test whether the
2687 medium is write-protected).
2688 Example: quirks=0419:aaf5:rl,0421:0433:rc
2689
Stephen Boydac1667d2011-08-13 12:34:50 -07002690 user_debug= [KNL,ARM]
2691 Format: <int>
2692 See arch/arm/Kconfig.debug help text.
2693 1 - undefined instruction events
2694 2 - system calls
2695 4 - invalid data aborts
2696 8 - SIGSEGV faults
2697 16 - SIGBUS faults
2698 Example: user_debug=31
2699
Ian Campbell14315592010-02-17 10:38:10 +00002700 userpte=
2701 [X86] Flags controlling user PTE allocations.
2702
2703 nohigh = do not allocate PTE pages in
2704 HIGHMEM regardless of setting
2705 of CONFIG_HIGHPTE.
2706
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302707 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002708 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002709 vdso=1: enable VDSO (default)
2710 vdso=0: disable VDSO mapping
2711
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302712 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002713 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2714 vdso32=1: enable 32-bit VDSO (default)
2715 vdso32=0: disable 32-bit VDSO mapping
2716
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002717 vector= [IA-64,SMP]
2718 vector=percpu: enable percpu vector domain
2719
Linus Torvalds1da177e2005-04-16 15:20:36 -07002720 video= [FB] Frame buffer configuration
2721 See Documentation/fb/modedb.txt.
2722
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002723 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002724 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002725 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002726 Use vga=ask for menu.
2727 This is actually a boot loader parameter; the value is
2728 passed to the kernel using a special protocol.
2729
Randy Dunlapa9913042005-10-23 12:57:11 -07002730 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731 size of <nn>. This can be used to increase the
2732 minimum size (128MB on x86). It can also be used to
2733 decrease the size and leave more room for directly
2734 mapped kernel RAM.
2735
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002736 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2737 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002739 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2740 Format: <command>
2741
2742 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2743 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002744
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002745 vsyscall= [X86-64]
2746 Controls the behavior of vsyscalls (i.e. calls to
2747 fixed addresses of 0xffffffffff600x00 from legacy
2748 code). Most statically-linked binaries and older
2749 versions of glibc use these calls. Because these
2750 functions are at fixed addresses, they make nice
2751 targets for exploits that can control RIP.
2752
Adrian Bunk2b666852011-10-06 00:40:47 +03002753 emulate Vsyscalls turn into traps and are emulated
2754 reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002755
Adrian Bunk2b666852011-10-06 00:40:47 +03002756 native [default] Vsyscalls are native syscall
2757 instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002758 This is a little bit faster than trapping
2759 and makes a few dynamic recompilers work
2760 better than they would in emulation mode.
2761 It also makes exploits much easier to write.
2762
2763 none Vsyscalls don't work at all. This makes
2764 them quite hard to use for exploits but
2765 might break your system.
2766
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002767 vt.cur_default= [VT] Default cursor shape.
2768 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2769 the parameters of the <Esc>[?A;B;Cc escape sequence;
2770 see VGA-softcursor.txt. Default: 2 = underline.
2771
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002772 vt.default_blu= [VT]
2773 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2774 Change the default blue palette of the console.
2775 This is a 16-member array composed of values
2776 ranging from 0-255.
2777
2778 vt.default_grn= [VT]
2779 Format: <green0>,<green1>,<green2>,...,<green15>
2780 Change the default green palette of the console.
2781 This is a 16-member array composed of values
2782 ranging from 0-255.
2783
2784 vt.default_red= [VT]
2785 Format: <red0>,<red1>,<red2>,...,<red15>
2786 Change the default red palette of the console.
2787 This is a 16-member array composed of values
2788 ranging from 0-255.
2789
2790 vt.default_utf8=
2791 [VT]
2792 Format=<0|1>
2793 Set system-wide default UTF-8 mode for all tty's.
2794 Default is 1, i.e. UTF-8 mode is enabled for all
2795 newly opened terminals.
2796
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002797 vt.global_cursor_default=
2798 [VT]
2799 Format=<-1|0|1>
2800 Set system-wide default for whether a cursor
2801 is shown on new VTs. Default is -1,
2802 i.e. cursors will be created by default unless
2803 overridden by individual drivers. 0 will hide
2804 cursors, 1 will display them.
2805
Randy Dunlap4724ba52010-05-03 11:42:52 -07002806 watchdog timers [HW,WDT] For information on watchdog timers,
2807 see Documentation/watchdog/watchdog-parameters.txt
2808 or other driver-specific files in the
2809 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002810
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002811 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2812 default x2apic cluster mode on platforms
2813 supporting x2apic.
2814
Jacob Panbb24c472009-09-02 07:37:17 -07002815 x86_mrst_timer= [X86-32,APBT]
2816 Choose timer option for x86 Moorestown MID platform.
2817 Two valid options are apbt timer only and lapic timer
2818 plus one apbt timer for broadcast timer.
2819 x86_mrst_timer=apbt_only | lapic_and_apbt
2820
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2822 xd_geo= See header of drivers/block/xd.c.
2823
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002824 xen_emul_unplug= [HW,X86,XEN]
2825 Unplug Xen emulated devices
2826 Format: [unplug0,][unplug1]
2827 ide-disks -- unplug primary master IDE devices
2828 aux-ide-disks -- unplug non-primary-master IDE devices
2829 nics -- unplug network devices
2830 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002831 unnecessary -- unplugging emulated devices is
2832 unnecessary even if the host did not respond to
2833 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002834 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002835
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002837 Format:
2838 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839
Randy Dunlapa9913042005-10-23 12:57:11 -07002840______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002841
2842TODO:
2843
Linus Torvalds1da177e2005-04-16 15:20:36 -07002844 Add more DRM drivers.