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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
Rusty Russell5888bcc2014-05-14 10:33:45 +09304The following is a consolidated list of the kernel parameters as
5implemented by the __setup(), core_param() and module_param() macros
6and sorted into English Dictionary order (defined as ignoring all
7punctuation and sorting digits before letters in a case insensitive
8manner), and with descriptions where known.
Linus Torvalds1da177e2005-04-16 15:20:36 -07009
Rusty Russell5888bcc2014-05-14 10:33:45 +093010The kernel parses parameters from the kernel command line up to "--";
11if it doesn't recognize a parameter and it doesn't contain a '.', the
12parameter gets passed to init: parameters with '=' go into init's
13environment, others are passed as command line arguments to init.
14Everything after "--" is passed as an argument to init.
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
Rusty Russell5888bcc2014-05-14 10:33:45 +093016Module parameters can be specified in two ways: via the kernel command
17line with a module name prefix, or via modprobe, e.g.:
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
Rusty Russell5888bcc2014-05-14 10:33:45 +093019 (kernel command line) usbcore.blinkenlights=1
20 (modprobe command line) modprobe usbcore blinkenlights=1
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Rusty Russell5888bcc2014-05-14 10:33:45 +093022Parameters for modules which are built into the kernel need to be
23specified on the kernel command line. modprobe looks through the
24kernel command line (/proc/cmdline) and collects module parameters
25when it loads a module, so the kernel command line can be used for
26loadable modules too.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Randy Dunlapca1eda22009-05-06 16:02:58 -070028Hyphens (dashes) and underscores are equivalent in parameter names, so
29 log_buf_len=1M print-fatal-signals=1
30can also be entered as
31 log-buf-len=1M print_fatal_signals=1
32
Rusty Russell5888bcc2014-05-14 10:33:45 +093033Double-quotes can be used to protect spaces in values, e.g.:
34 param="spaces in here"
Randy Dunlapca1eda22009-05-06 16:02:58 -070035
Stefan Richtera901ebb2006-04-01 01:43:18 +020036This document may not be entirely up to date and comprehensive. The command
37"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
38module. Loadable modules, after being loaded into the running kernel, also
39reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
40parameters may be changed at runtime by the command
41"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
42
Stefan Richter6585fa82006-04-01 01:44:30 +020043The parameters listed below are only valid if certain kernel build options were
44enabled and if respective hardware is present. The text in square brackets at
45the beginning of each description states the restrictions within which a
46parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100049 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 ALSA ALSA sound support is enabled.
51 APIC APIC support is enabled.
52 APM Advanced Power Management support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070053 ARM ARM architecture is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020054 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080056 BLACKFIN Blackfin architecture is enabled.
Olof Johansson1e435252013-04-27 14:10:18 -070057 CLK Common clock infrastructure is enabled.
Robert Tivy5c71d612013-03-28 18:41:46 -070058 CMA Contiguous Memory Area support is enabled.
Alan Cox9cfe2682011-01-25 14:18:38 +000059 DRM Direct Rendering Management support is enabled.
60 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
62 EFI EFI Partitioning (GPT) is enabled
63 EIDE EIDE/ATAPI support is enabled.
Mimi Zohar7102ebc2011-05-12 18:33:20 -040064 EVM Extended Verification Module
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 FB The frame buffer device is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070066 FTRACE Function tracing enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070067 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050070 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070072 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080073 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 ISAPNP ISA PnP code is enabled.
75 ISDN Appropriate ISDN support is enabled.
76 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050077 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020078 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070079 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 LP Printer support is enabled.
81 LOOP Loopback device support is enabled.
82 M68k M68k architecture is enabled.
83 These options have more detailed description inside of
84 Documentation/m68k/kernel-options.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 MDA MDA console support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070086 MIPS MIPS architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070088 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070089 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 NET Appropriate network support is enabled.
91 NUMA NUMA support is enabled.
92 NFS Appropriate NFS support is enabled.
93 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070094 PV_OPS A paravirtualized kernel is enabled.
95 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 PARISC The PA-RISC architecture is enabled.
97 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070098 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 PCMCIA The PCMCIA subsystem is enabled.
100 PNP Plug & Play support is enabled.
101 PPC PowerPC architecture is enabled.
102 PPT Parallel port support is enabled.
103 PS2 Appropriate PS/2 support is enabled.
104 RAM RAM disk support is enabled.
105 S390 S390 architecture is enabled.
106 SCSI Appropriate SCSI support is enabled.
Randy Dunlap163475f2010-08-14 12:36:14 -0700107 A lot of drivers have their options described inside
108 the Documentation/scsi/ sub-directory.
James Morris20510f22007-10-16 23:31:32 -0700109 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 SELINUX SELinux support is enabled.
John Johansenc1c124e2010-07-29 14:48:09 -0700111 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +0900113 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 SMP The kernel is an SMP kernel.
115 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700116 SWSUSP Software suspend (hibernation) is enabled.
117 SUSPEND System suspend states are enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300118 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500120 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 USB USB support is enabled.
122 USBHID USB Human Interface Device support is enabled.
123 V4L Video For Linux support is enabled.
Pawel Moll81a054c2012-05-09 18:30:16 +0100124 VMMIO Driver for memory mapped virtio devices is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 VGA The VGA console has been enabled.
126 VT Virtual terminal support is enabled.
127 WDT Watchdog support is enabled.
128 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700129 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 X86-64 X86-64 architecture is enabled.
131 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700132 Documentation/x86/x86_64/boot-options.txt .
Randy Dunlap16290242011-08-13 12:34:52 -0700133 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100134 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135
136In addition, the following text indicates that the option:
137
138 BUGS= Relates to possible processor bugs on the said processor.
139 KNL Is a kernel start-up parameter.
140 BOOT Is a boot loader parameter.
141
142Parameters denoted with BOOT are actually interpreted by the boot
143loader, and have no meaning to the kernel directly.
144Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500145need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
Karsten Weiss55588702007-02-13 13:26:21 +0100147There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700148See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100149
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
151a trailing = on the name of any parameter states that that parameter will
152be entered as an environment variable, whereas its absence indicates that
153it will appear as a kernel argument readable via /proc/cmdline by programs
154running once the system is up.
155
jens m. noedler9c4751f2006-09-29 02:00:27 -0700156The number of kernel parameters is not limited, but the length of the
157complete command line (parameters including spaces etc.) is limited to
158a fixed number of characters. This limit depends on the architecture
159and is between 256 and 4096 characters. It is defined in the file
160./include/asm/setup.h as COMMAND_LINE_SIZE.
161
Ahmed S. Darwish7a19a232011-02-20 20:08:35 -0800162Finally, the [KMG] suffix is commonly described after a number of kernel
163parameter values. These 'K', 'M', and 'G' letters represent the _binary_
164multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
165bytes respectively. Such letter suffixes can also be entirely omitted.
166
jens m. noedler9c4751f2006-09-29 02:00:27 -0700167
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530168 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800169 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500170 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 force -- enable ACPI if default was off
172 off -- disable ACPI if default was on
173 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700174 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800176 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800177 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
Paul Bolle395cf962011-08-15 02:02:26 +0200179 See also Documentation/power/runtime_pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
Takao Indoh4996c022011-07-14 18:05:21 -0400181 acpi_rsdp= [ACPI,EFI,KEXEC]
182 Pass the RSDP address to the kernel, mostly used
183 on machines running EFI runtime service to boot the
184 second kernel for kdump.
185
Len Browna1fdcc02007-03-11 03:26:14 -0400186 acpi_apic_instance= [ACPI, IOAPIC]
187 Format: <int>
188 2: use 2nd APIC table, if available
189 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400190 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400191
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200192 acpi_backlight= [HW,ACPI]
193 acpi_backlight=vendor
194 acpi_backlight=video
195 If set to vendor, prefer vendor specific driver
196 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
197 of the ACPI video.ko driver.
198
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700199 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
200 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700202 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
203 debug output. Bits in debug_layer correspond to a
204 _COMPONENT in an ACPI source file, e.g.,
205 #define _COMPONENT ACPI_PCI_COMPONENT
206 Bits in debug_level correspond to a level in
207 ACPI_DEBUG_PRINT statements, e.g.,
208 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600209 The debug_level mask defaults to "info". See
210 Documentation/acpi/debug.txt for more information about
211 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600213 Enable processor driver info messages:
214 acpi.debug_layer=0x20000000
215 Enable PCI/PCI interrupt routing info messages:
216 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700217 Enable AML "Debug" output, i.e., stores to the Debug
218 object while interpreting AML:
219 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700220 Enable all messages related to ACPI hardware:
221 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200222
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700223 Some values produce so much output that the system is
224 unusable. The "log_buf_len" parameter may be useful
225 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800226
Lv Zheng4fc0a7e2014-05-31 08:15:02 +0800227 acpi_force_table_verification [HW,ACPI]
228 Enable table checksum verification during early stage.
229 By default, this is disabled due to x86 early mapping
230 size limitation.
231
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700232 acpi_irq_balance [HW,ACPI]
233 ACPI will balance active IRQs
234 default in APIC mode
235
236 acpi_irq_nobalance [HW,ACPI]
237 ACPI will not move active IRQs (default)
238 default in PIC mode
239
240 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
241 Format: <irq>,<irq>...
242
243 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
244 use by PCI
245 Format: <irq>,<irq>...
246
Lv Zheng08e1d7c2014-03-24 14:49:22 +0800247 acpi_no_auto_serialize [HW,ACPI]
248 Disable auto-serialization of AML methods
Bob Moore22b5afc2014-03-24 14:49:00 +0800249 AML control methods that contain the opcodes to create
250 named objects will be marked as "Serialized" by the
251 auto-serialization feature.
Lv Zheng08e1d7c2014-03-24 14:49:22 +0800252 This feature is enabled by default.
253 This option allows to turn off the feature.
Bob Moore22b5afc2014-03-24 14:49:00 +0800254
Lv Zhenga94e88c2014-04-04 12:39:11 +0800255 acpi_no_static_ssdt [HW,ACPI]
256 Disable installation of static SSDTs at early boot time
257 By default, SSDTs contained in the RSDT/XSDT will be
258 installed automatically and they will appear under
259 /sys/firmware/acpi/tables.
260 This option turns off this feature.
261 Note that specifying this option does not affect
262 dynamic table installation which will install SSDT
263 tables to /sys/firmware/acpi/tables/dynamic.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700264
Lv Zheng4dde5072014-02-11 11:01:52 +0800265 acpica_no_return_repair [HW, ACPI]
266 Disable AML predefined validation mechanism
267 This mechanism can repair the evaluation result to make
268 the return objects more ACPI specification compliant.
269 This option is useful for developers to identify the
270 root cause of an AML interpreter issue when the issue
271 has something to do with the repair mechanism.
272
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700273 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
274 Format: To spoof as Windows 98: ="Microsoft Windows"
275
276 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
Lv Zheng5dc17982013-07-22 16:08:25 +0800277 acpi_osi="string1" # add string1
278 acpi_osi="!string2" # remove string2
Lv Zheng741d8122013-07-22 16:08:36 +0800279 acpi_osi=!* # remove all strings
Lv Zheng5dc17982013-07-22 16:08:25 +0800280 acpi_osi=! # disable all built-in OS vendor
281 strings
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700282 acpi_osi= # disable all strings
283
Lv Zheng5dc17982013-07-22 16:08:25 +0800284 'acpi_osi=!' can be used in combination with single or
285 multiple 'acpi_osi="string1"' to support specific OS
286 vendor string(s). Note that such command can only
287 affect the default state of the OS vendor strings, thus
288 it cannot affect the default state of the feature group
289 strings and the current state of the OS vendor strings,
290 specifying it multiple times through kernel command line
Lv Zheng741d8122013-07-22 16:08:36 +0800291 is meaningless. This command is useful when one do not
292 care about the state of the feature group strings which
293 should be controlled by the OSPM.
Lv Zheng5dc17982013-07-22 16:08:25 +0800294 Examples:
295 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
296 to 'acpi_osi="Windows 2000" acpi_osi=!', they all
297 can make '_OSI("Windows 2000")' TRUE.
298
299 'acpi_osi=' cannot be used in combination with other
300 'acpi_osi=' command lines, the _OSI method will not
301 exist in the ACPI namespace. NOTE that such command can
302 only affect the _OSI support state, thus specifying it
303 multiple times through kernel command line is also
304 meaningless.
305 Examples:
306 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
307 FALSE.
308
Lv Zheng741d8122013-07-22 16:08:36 +0800309 'acpi_osi=!*' can be used in combination with single or
310 multiple 'acpi_osi="string1"' to support specific
311 string(s). Note that such command can affect the
312 current state of both the OS vendor strings and the
313 feature group strings, thus specifying it multiple times
314 through kernel command line is meaningful. But it may
315 still not able to affect the final state of a string if
316 there are quirks related to this string. This command
317 is useful when one want to control the state of the
318 feature group strings to debug BIOS issues related to
319 the OSPM features.
320 Examples:
321 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
322 '_OSI("Module Device")' FALSE.
323 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
324 '_OSI("Module Device")' TRUE.
325 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
326 equivalent to
327 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
328 and
329 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
330 they all will make '_OSI("Windows 2000")' TRUE.
331
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530332 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700333 Override the pmtimer bug detection: force the kernel
334 to assume that this machine's pmtimer latches its value
335 and always returns good values.
336
Randy Dunlap4af94f32009-04-17 18:30:28 -0700337 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
338 Format: { level | edge | high | low }
339
Randy Dunlap4af94f32009-04-17 18:30:28 -0700340 acpi_skip_timer_override [HW,ACPI]
341 Recognize and ignore IRQ0/pin2 Interrupt Override.
342 For broken nForce2 BIOS resulting in XT-PIC timer.
343
344 acpi_sleep= [HW,ACPI] Sleep options
345 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Amerigo Wangc3b07952011-05-10 21:09:38 +0200346 old_ordering, nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700347 See Documentation/power/video.txt for information on
348 s3_bios and s3_mode.
349 s3_beep is for debugging; it makes the PC's speaker beep
350 as soon as the kernel's real-mode entry point is called.
351 s4_nohwsig prevents ACPI hardware signature from being
352 used during resume from hibernation.
353 old_ordering causes the ACPI 1.0 ordering of the _PTS
354 control method, with respect to putting devices into
355 low power states, to be enforced (the ACPI 2.0 ordering
356 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200357 nonvs prevents the kernel from saving/restoring the
358 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800359 sci_force_enable causes the kernel to set SCI_EN directly
360 on resume from S1/S3 (which is against the ACPI spec,
361 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700362
363 acpi_use_timer_override [HW,ACPI]
364 Use timer override. For some broken Nvidia NF5 boards
365 that require a timer override, but don't have HPET
366
Luca Tettamanti7e905602009-03-30 00:01:27 +0200367 acpi_enforce_resources= [ACPI]
368 { strict | lax | no }
369 Check for resource conflicts between native drivers
370 and ACPI OperationRegions (SystemIO and SystemMemory
371 only). IO ports and memory declared in ACPI might be
372 used by the ACPI subsystem in arbitrary AML code and
373 can interfere with legacy drivers.
374 strict (default): access to resources claimed by ACPI
375 is denied; legacy drivers trying to access reserved
376 resources will fail to bind to device using them.
377 lax: access to resources claimed by ACPI is allowed;
378 legacy drivers trying to access reserved resources
379 will bind successfully but a warning message is logged.
380 no: ACPI OperationRegions are not marked as reserved,
381 no further checks are performed.
382
Prarit Bhargava00159a22014-01-14 14:21:13 -0500383 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
384 kernels.
385
Randy Dunlap4af94f32009-04-17 18:30:28 -0700386 add_efi_memmap [EFI; X86] Include EFI memory map in
387 kernel's map of available physical RAM.
388
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700389 agp= [AGP]
390 { off | try_unsupported }
391 off: disable AGP support
392 try_unsupported: try to drive unsupported chipsets
393 (may crash computer or cause data corruption)
394
Randy Dunlapbcfde332010-06-07 17:10:38 -0700395 ALSA [HW,ALSA]
396 See Documentation/sound/alsa/alsa-parameters.txt
397
Russell Kingd944d542010-02-20 16:13:29 +0000398 alignment= [KNL,ARM]
399 Allow the default userspace alignment fault handler
400 behaviour to be specified. Bit 0 enables warnings,
401 bit 1 enables fixups, and bit 2 sends a segfault.
402
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200403 align_va_addr= [X86-64]
404 Align virtual addresses by clearing slice [14:12] when
405 allocating a VMA at process creation time. This option
406 gives you up to 3% performance improvement on AMD F15h
407 machines (where it is enabled by default) for a
408 CPU-intensive style benchmark, and it can vary highly in
409 a microbenchmark depending on workload and compiler.
410
Borislav Petkov8360ee22011-11-21 12:10:19 +0100411 32: only for 32-bit processes
412 64: only for 64-bit processes
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200413 on: enable for both 32- and 64-bit processes
414 off: disable for both 32- and 64-bit processes
415
Steven Rostedt (Red Hat)55034cd2013-03-07 22:48:09 -0500416 alloc_snapshot [FTRACE]
417 Allocate the ftrace snapshot buffer on boot up when the
418 main buffer is allocated. This is handy if debugging
419 and you need to use tracing_snapshot() on boot up, and
420 do not want to use tracing_snapshot_alloc() as it needs
421 to be done where GFP_KERNEL allocations are allowed.
422
Sedat Dilek89e0b9a32011-12-05 23:08:32 +0100423 amd_iommu= [HW,X86-64]
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200424 Pass parameters to the AMD IOMMU driver in the system.
425 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900426 fullflush - enable flushing of IO/TLB entries when
427 they are unmapped. Otherwise they are
428 flushed before they will be reused, which
429 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200430 off - do not initialize any AMD IOMMU found in
431 the system
Joerg Roedel5abcdba2011-12-01 15:49:45 +0100432 force_isolation - Force device isolation for all
433 devices. The IOMMU driver is not
434 allowed anymore to lift isolation
435 requirements as needed. This option
436 does not override iommu=pt
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900437
Shuah Khanc099cf12012-05-24 15:58:25 -0600438 amd_iommu_dump= [HW,X86-64]
439 Enable AMD IOMMU driver option to dump the ACPI table
440 for AMD IOMMU. With this option enabled, AMD IOMMU
441 driver will print ACPI tables for AMD IOMMU during
442 IOMMU initialization.
443
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 amijoy.map= [HW,JOY] Amiga joystick support
445 Map of devices attached to JOY0DAT and JOY1DAT
446 Format: <a>,<b>
Paul Bolle395cf962011-08-15 02:02:26 +0200447 See also Documentation/input/joystick.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448
449 analog.map= [HW,JOY] Analog joystick and gamepad support
450 Specifies type or capabilities of an analog joystick
451 connected to one of 16 gameports
452 Format: <type1>,<type2>,..<type16>
453
Randy Dunlapa9913042005-10-23 12:57:11 -0700454 apc= [HW,SPARC]
455 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 Format: noidle
457 Disable APC CPU standby support. SPARCstation-Fox does
458 not play well with APC CPU idle - disable it if you have
459 APC and your system crashes randomly.
460
Randy Dunlapca1eda22009-05-06 16:02:58 -0700461 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700462 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 Format: { quiet (default) | verbose | debug }
464 Change the amount of debugging information output
465 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700466
Brian Haleyb0f83b22010-02-04 13:36:50 -0800467 autoconf= [IPV6]
468 See Documentation/networking/ipv6.txt.
469
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400470 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
471 Limit apic dumping. The parameter defines the maximal
472 number of local apics being dumped. Also it is possible
473 to set it to "all" by meaning -- no limit here.
474 Format: { 1 (default) | 2 | ... | all }.
475 The parameter valid if only apic=debug or
476 apic=verbose is specified.
477 Example: apic=debug show_lapic=all
478
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700480 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
483 Format: <io>,<irq>,<nodeID>
484
485 ataflop= [HW,M68k]
486
487 atarimouse= [HW,MOUSE] Atari Mouse
488
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
490 EzKey and similar keyboards
491
492 atkbd.reset= [HW] Reset keyboard during initialization
493
Randy Dunlapa9913042005-10-23 12:57:11 -0700494 atkbd.set= [HW] Select keyboard code set
495 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496
497 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
498 keyboards
499
500 atkbd.softraw= [HW] Choose between synthetic and real raw mode
501 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700502
503 atkbd.softrepeat= [HW]
504 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505
Richard Guy Briggsa106fb02013-09-23 21:53:35 -0400506 audit= [KNL] Enable the audit sub-system
507 Format: { "0" | "1" } (0 = disabled, 1 = enabled)
Eric Parisd7961142014-01-13 16:01:06 -0500508 0 - kernel audit is disabled and can not be enabled
509 until the next reboot
510 unset - kernel audit is initialized but disabled and
511 will be fully enabled by the userspace auditd.
512 1 - kernel audit is initialized and partially enabled,
513 storing at most audit_backlog_limit messages in
514 RAM until it is fully enabled by the userspace
515 auditd.
Richard Guy Briggsa106fb02013-09-23 21:53:35 -0400516 Default: unset
Richard Guy Briggsf3411cb2013-09-17 12:34:52 -0400517
Richard Guy Briggsf910fde2013-09-17 12:34:52 -0400518 audit_backlog_limit= [KNL] Set the audit queue size limit.
519 Format: <int> (must be >=0)
520 Default: 64
521
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 baycom_epp= [HW,AX25]
523 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700524
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
526 Format: <io>,<mode>
527 See header of drivers/net/hamradio/baycom_par.c.
528
Randy Dunlapa9913042005-10-23 12:57:11 -0700529 baycom_ser_fdx= [HW,AX25]
530 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 Format: <io>,<irq>,<mode>[,<baud>]
532 See header of drivers/net/hamradio/baycom_ser_fdx.c.
533
Randy Dunlapa9913042005-10-23 12:57:11 -0700534 baycom_ser_hdx= [HW,AX25]
535 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 Format: <io>,<irq>,<mode>
537 See header of drivers/net/hamradio/baycom_ser_hdx.c.
538
Paul Gortmaker080506a2013-09-30 13:45:19 -0700539 blkdevparts= Manual partition parsing of block device(s) for
540 embedded devices based on command line input.
541 See Documentation/block/cmdline-partition.txt
542
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700543 boot_delay= Milliseconds to delay each printk during boot.
544 Values larger than 10 seconds (10000) are changed to
545 no delay (0).
546 Format: integer
547
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700548 bootmem_debug [KNL] Enable bootmem allocator debug messages.
549
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700551 bttv.radio= Most important insmod options are available as
552 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
Paul Bolle395cf962011-08-15 02:02:26 +0200554 bttv.tuner=
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000556 bulk_remove=off [PPC] This parameter disables the use of the pSeries
557 firmware feature for flushing multiple hpte entries
558 at a time.
559
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 c101= [NET] Moxa C101 synchronous serial card
561
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700562 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 Sometimes CPU hardware bugs make them report the cache
564 size incorrectly. The kernel will attempt work arounds
565 to fix known problems, but for some CPUs it is not
566 possible to determine what the correct size should be.
567 This option provides an override for these situations.
568
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +0300569 ca_keys= [KEYS] This parameter identifies a specific key(s) on
570 the system trusted keyring to be used for certificate
571 trust validation.
Dmitry Kasatkin32c47412014-06-17 11:56:59 +0300572 format: { id:<keyid> | builtin }
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +0300573
Florian Fainellifd1bb4c2014-06-25 16:41:13 -0700574 cca= [MIPS] Override the kernel pages' cache coherency
575 algorithm. Accepted values range from 0 to 7
576 inclusive. See arch/mips/include/asm/pgtable-bits.h
577 for platform specific values (SB1, Loongson3 and
578 others).
579
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100580 ccw_timeout_log [S390]
581 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582
Paul Menage8bab8dd2008-04-04 14:29:57 -0700583 cgroup_disable= [KNL] Disable a particular controller
584 Format: {name of the controller(s) to disable}
Qiang Huangca0bdbb2013-11-06 13:18:09 -0800585 The effects of cgroup_disable=foo are:
586 - foo isn't auto-mounted if you mount all cgroups in
587 a single hierarchy
588 - foo isn't visible as an individually mountable
589 subsystem
590 {Currently only "memory" controller deal with this and
591 cut the overhead, others just disable the usage. So
592 only cgroup_disable=memory is actually worthy}
Paul Menage8bab8dd2008-04-04 14:29:57 -0700593
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 checkreqprot [SELINUX] Set initial checkreqprot flag value.
595 Format: { "0" | "1" }
596 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700597 0 -- check protection applied by kernel (includes
598 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 1 -- check protection requested by application.
600 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700601 Value can be changed at runtime via
602 /selinux/checkreqprot.
603
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100604 cio_ignore= [S390]
605 See Documentation/s390/CommonIO for details.
Olof Johansson1e435252013-04-27 14:10:18 -0700606 clk_ignore_unused
607 [CLK]
Mike Turquettee156ee52014-09-30 14:24:38 -0700608 Prevents the clock framework from automatically gating
609 clocks that have not been explicitly enabled by a Linux
610 device driver but are enabled in hardware at reset or
611 by the bootloader/firmware. Note that this does not
612 force such clocks to be always-on nor does it reserve
613 those clocks in any way. This parameter is useful for
614 debug and development, but should not be needed on a
615 platform with proper driver support. For more
616 information, see Documentation/clk.txt.
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100617
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700618 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700619 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200620 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700621 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200622 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 Format: { pit | tsc | cyclone | pmtmr }
624
John Stultz592913e2010-07-13 17:56:20 -0700625 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700626 Format: <string>
627 Override the default clocksource and use the clocksource
628 with the name specified.
629 Some clocksource names to choose from, depending on
630 the platform:
631 [all] jiffies (this is the base, fallback clocksource)
632 [ACPI] acpi_pm
633 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
634 pxa_timer,timer3,32k_counter,timer0_1
635 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700636 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700637 scx200_hrt on Geode; cyclone on IBM x440
638 [MIPS] MIPS
639 [PARISC] cr16
640 [S390] tod
641 [SH] SuperH
642 [SPARC64] tick
643 [X86-64] hpet,tsc
644
Andi Kleenac72e782008-01-30 13:33:21 +0100645 clearcpuid=BITNUM [X86]
646 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800647 arch/x86/include/asm/cpufeature.h for the valid bit
648 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100649 stable over kernel options, but the vendor specific
650 ones should be.
651 Also note that user programs calling CPUID directly
652 or using the feature without checking anything
653 will still see it. This just prevents it from
654 being used by the kernel or shown in /proc/cpuinfo.
655 Also note the kernel might malfunction if you disable
656 some critical bits.
657
Akinobu Mita5ea3b1b2014-06-04 16:06:54 -0700658 cma=nn[MG]@[start[MG][-end[MG]]]
659 [ARM,X86,KNL]
660 Sets the size of kernel global memory area for
661 contiguous memory allocations and optionally the
662 placement constraint by the physical address range of
Jean Delvaref0d6d1f2014-10-09 15:29:41 -0700663 memory allocations. A value of 0 disables CMA
664 altogether. For more information, see
Marek Szyprowskic64be2b2011-12-29 13:09:51 +0100665 include/linux/dma-contiguous.h
666
Robert Jennings14f966e2009-04-15 05:55:32 +0000667 cmo_free_hint= [PPC] Format: { yes | no }
668 Specify whether pages are marked as being inactive
669 when they are freed. This is used in CMO environments
670 to determine OS memory pressure for page stealing by
671 a hypervisor.
672 Default: yes
673
Marek Szyprowskic7909502011-12-29 13:09:51 +0100674 coherent_pool=nn[KMG] [ARM,KNL]
675 Sets the size of memory pool for coherent, atomic dma
Marek Szyprowskie9da6e92012-07-30 09:11:33 +0200676 allocations, by default set to 256K.
Marek Szyprowskic7909502011-12-29 13:09:51 +0100677
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530678 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100679 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100680 Range: 0 - 8192
681 Default: 64
682
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700684 Format:
685 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686
687 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
688 Format: <io>[,<irq>]
689
Randy Dunlapa9913042005-10-23 12:57:11 -0700690 com90xx= [HW,NET]
691 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 Format: <io>[,<irq>[,<memstart>]]
693
694 condev= [HW,S390] console device
695 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700696
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 console= [KNL] Output console device and options.
698
699 tty<n> Use the virtual console device <n>.
700
701 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800702 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800704 the form "bbbbpnf", where "bbbb" is the baud rate,
705 "p" is parity ("n", "o", or "e"), "n" is number of
706 bits, and "f" is flow control ("r" for RTS or
707 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800709 See Documentation/serial-console.txt for more
710 information. See
711 Documentation/networking/netconsole.txt for an
712 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700714 uart[8250],io,<addr>[,options]
715 uart[8250],mmio,<addr>[,options]
Peter Hurleyca782f12015-04-06 10:52:39 -0400716 uart[8250],mmio32,<addr>[,options]
717 uart[8250],0x<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 Start an early, polled-mode console on the 8250/16550
719 UART at the specified I/O port or MMIO address,
Peter Hurleyca782f12015-04-06 10:52:39 -0400720 switching to the matching ttyS device later.
721 MMIO inter-register address stride is either 8-bit
722 (mmio) or 32-bit (mmio32).
723 If none of [io|mmio|mmio32], <addr> is assumed to be
724 equivalent to 'mmio'. 'options' are specified in the
725 same format described for ttyS above; if unspecified,
726 the h/w is not re-initialized.
727
Konrad Rzeszutek Wilka2fd6412013-02-25 15:54:09 -0500728 hvc<n> Use the hypervisor console device <n>. This is for
729 both Xen and PowerPC hypervisors.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700731 If the device connected to the port is not a TTY but a braille
732 device, prepend "brl," before the device type, for instance
733 console=brl,ttyS0
734 For now, only VisioBraille is supported.
735
Daniel Mackf324edc2009-06-16 15:33:52 -0700736 consoleblank= [KNL] The console blank (screen saver) timeout in
737 seconds. Defaults to 10*60 = 10mins. A value of 0
738 disables the blank timer.
739
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800740 coredump_filter=
741 [KNL] Change the default value for
742 /proc/<pid>/coredump_filter.
743 See also Documentation/filesystems/proc.txt.
744
Len Brown62027ae2011-04-01 18:13:10 -0400745 cpuidle.off=1 [CPU_IDLE]
746 disable the cpuidle sub-system
747
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700749 Format:
750 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800752 crashkernel=size[KMG][@offset[KMG]]
753 [KNL] Using kexec, Linux can switch to a 'crash kernel'
754 upon panic. This parameter reserves the physical
755 memory region [offset, offset + size] for that kernel
756 image. If '@offset' is omitted, then a suitable offset
757 is selected automatically. Check
758 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700759
Bernhard Wallefb391592007-10-18 23:41:02 -0700760 crashkernel=range1:size1[,range2:size2,...][@offset]
761 [KNL] Same as above, but depends on the memory
762 in the running system. The syntax of range is
763 start-[end] where start and end are both
764 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800765 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700766
Yinghai Luadbc7422013-04-15 22:23:48 -0700767 crashkernel=size[KMG],high
Yinghai Lu55a20ee2013-04-15 22:23:47 -0700768 [KNL, x86_64] range could be above 4G. Allow kernel
769 to allocate physical memory region from top, so could
770 be above 4G if system have more than 4G ram installed.
771 Otherwise memory region will be allocated below 4G, if
772 available.
773 It will be ignored if crashkernel=X is specified.
Yinghai Luadbc7422013-04-15 22:23:48 -0700774 crashkernel=size[KMG],low
775 [KNL, x86_64] range under 4G. When crashkernel=X,high
776 is passed, kernel could allocate physical memory region
Yinghai Luc729de82013-04-15 22:23:45 -0700777 above 4G, that cause second kernel crash on system
778 that require some amount of low memory, e.g. swiotlb
779 requires at least 64M+32K low memory. Kernel would
780 try to allocate 72M below 4G automatically.
781 This one let user to specify own low range under 4G
782 for second kernel instead.
783 0: to disable low allocation.
Yinghai Luadbc7422013-04-15 22:23:48 -0700784 It will be ignored when crashkernel=X,high is not used
Yinghai Lu55a20ee2013-04-15 22:23:47 -0700785 or memory reserved is below 4G.
Yinghai Luc729de82013-04-15 22:23:45 -0700786
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 cs89x0_dma= [HW,NET]
788 Format: <dma>
789
790 cs89x0_media= [HW,NET]
791 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700792
Randy Dunlapa9913042005-10-23 12:57:11 -0700793 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 See header of drivers/s390/block/dasd_devmap.c.
795
796 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
797 (one device per port)
798 Format: <port#>,<type>
799 See also Documentation/input/joystick-parport.txt
800
Thomas Renningera648ec02010-08-06 16:11:02 +0200801 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
802 time. See Documentation/dynamic-debug-howto.txt for
Jim Cromie29e36c92012-04-27 14:30:41 -0600803 details. Deprecated, see dyndbg.
Thomas Renningera648ec02010-08-06 16:11:02 +0200804
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 debug [KNL] Enable kernel debugging (events log level).
806
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700807 debug_locks_verbose=
808 [KNL] verbose self-tests
809 Format=<0|1>
810 Print debugging info while doing the locking API
811 self-tests.
812 We default to 0 (no extra messages), setting it to
813 1 will print _a lot_ more information - normally
814 only useful to kernel developers.
815
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700816 debug_objects [KNL] Enable object debugging
817
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500818 no_debug_objects
819 [KNL] Disable object debugging
820
Stanislaw Gruszkac0a32fc2012-01-10 15:07:28 -0800821 debug_guardpage_minorder=
822 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
823 parameter allows control of the order of pages that will
824 be intentionally kept free (and hence protected) by the
825 buddy allocator. Bigger value increase the probability
826 of catching random memory corruption, but reduce the
827 amount of memory for normal system use. The maximum
828 possible value is MAX_ORDER/2. Setting this parameter
829 to 1 or 2 should be enough to identify most random
830 memory corruption problems caused by bugs in kernel or
831 driver code when a CPU writes to (or reads from) a
832 random memory location. Note that there exists a class
833 of memory corruptions problems caused by buggy H/W or
834 F/W or by drivers badly programing DMA (basically when
835 memory is written at bus level and the CPU MMU is
836 bypassed) which are not detectable by
837 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
838 tracking down these problems.
839
Joonsoo Kim031bc572014-12-12 16:55:52 -0800840 debug_pagealloc=
841 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
842 parameter enables the feature at boot time. In
843 default, it is disabled. We can avoid allocating huge
844 chunk of memory for debug pagealloc if we don't enable
845 it at boot time and the system will work mostly same
846 with the kernel built without CONFIG_DEBUG_PAGEALLOC.
847 on: enable the feature
848
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200849 debugpat [X86] Enable PAT debugging
850
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200851 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852 Format: <area>[,<node>]
853 See also Documentation/networking/decnet.txt.
854
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700855 default_hugepagesz=
856 [same as hugepagesz=] The size of the default
857 HugeTLB page size. This is the size represented by
858 the legacy /proc/ hugepages APIs, used for SHM, and
859 default size when mounting hugetlbfs filesystems.
860 Defaults to the default architecture's huge page size
861 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700862
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 dhash_entries= [KNL]
864 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700865
Brian Haleyb0f83b22010-02-04 13:36:50 -0800866 disable= [IPV6]
867 See Documentation/networking/ipv6.txt.
868
HATAYAMA Daisuke151e0c72014-01-15 15:44:58 +0900869 disable_cpu_apicid= [X86,APIC,SMP]
870 Format: <int>
871 The number of initial APIC ID for the
872 corresponding CPU to be disabled at boot,
873 mostly used for the kdump 2nd kernel to
874 disable BSP to wake up multiple CPUs without
875 causing system reset or hang due to sending
876 INIT from AP to BSP.
877
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000878 disable_ddw [PPC/PSERIES]
879 Disable Dynamic DMA Window support. Use this if
880 to workaround buggy firmware.
881
Brian Haleyb0f83b22010-02-04 13:36:50 -0800882 disable_ipv6= [IPV6]
883 See Documentation/networking/ipv6.txt.
884
Yinghai Lu95ffa242008-04-29 03:52:33 -0700885 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700886 The kernel tries to adjust MTRR layout from continuous
887 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700888 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700889
Yinghai Lu093af8d2008-01-30 13:33:32 +0100890 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100891 By default the kernel will trim any uncacheable
892 memory out of your available memory pool based on
893 MTRR settings. This parameter disables that behavior,
894 possibly causing your machine to run very slowly.
895
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530896 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700897 Disable PIN 1 of APIC timer
898 Can be useful to work around chipset bugs.
899
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700900 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
901 this option disables the debugging code at boot.
902
903 dma_debug_entries=<number>
904 This option allows to tune the number of preallocated
905 entries for DMA-API debugging code. One entry is
906 required per DMA-API allocation. Use this if the
907 DMA-API debugging code disables itself because the
908 architectural default is too low.
909
Joerg Roedel1745de52009-05-22 21:49:51 +0200910 dma_debug_driver=<driver_name>
911 With this option the DMA-API debugging driver
912 filter feature can be enabled at boot time. Just
913 pass the driver to filter for as the parameter.
914 The filter can be disabled or changed to another
915 driver later using sysfs.
916
Carsten Emdeda0df922012-03-18 22:37:33 +0100917 drm_kms_helper.edid_firmware=[<connector>:]<file>
918 Broken monitors, graphic adapters and KVMs may
919 send no or incorrect EDID data sets. This parameter
920 allows to specify an EDID data set in the
921 /lib/firmware directory that is used instead.
922 Generic built-in EDID data sets are used, if one of
923 edid/1024x768.bin, edid/1280x1024.bin,
924 edid/1680x1050.bin, or edid/1920x1080.bin is given
925 and no file with the same name exists. Details and
926 instructions how to build your own EDID data are
927 available in Documentation/EDID/HOWTO.txt. An EDID
928 data set will only be used for a particular connector,
929 if its name and a colon are prepended to the EDID
930 name.
931
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 dscc4.setup= [NET]
933
Jim Cromie29e36c92012-04-27 14:30:41 -0600934 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
935 module.dyndbg[="val"]
936 Enable debug messages at boot time. See
937 Documentation/dynamic-debug-howto.txt for details.
938
Mark Salter56aeeba2014-04-07 15:39:53 -0700939 early_ioremap_debug [KNL]
940 Enable debug messages in early_ioremap support. This
941 is useful for tracking down temporary early mappings
942 which are not unmapped.
943
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700944 earlycon= [KNL] Output early console device and options.
Rob Herring0d3c6732014-04-18 17:19:57 -0500945
Michal Simek6fa62fc2014-09-10 12:43:02 +0200946 cdns,<addr>
947 Start an early, polled-mode console on a cadence serial
948 port at the specified address. The cadence serial port
949 must already be setup and configured. Options are not
950 yet supported.
951
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700952 uart[8250],io,<addr>[,options]
953 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700954 uart[8250],mmio32,<addr>[,options]
Peter Hurleyca782f12015-04-06 10:52:39 -0400955 uart[8250],0x<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700956 Start an early, polled-mode console on the 8250/16550
957 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700958 MMIO inter-register address stride is either 8-bit
959 (mmio) or 32-bit (mmio32).
Peter Hurleyca782f12015-04-06 10:52:39 -0400960 If none of [io|mmio|mmio32], <addr> is assumed to be
961 equivalent to 'mmio'. 'options' are specified in the
962 same format described for "console=ttyS<n>"; if
963 unspecified, the h/w is not initialized.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700964
Rob Herring0d3c6732014-04-18 17:19:57 -0500965 pl011,<addr>
966 Start an early, polled-mode console on a pl011 serial
967 port at the specified address. The pl011 serial port
968 must already be setup and configured. Options are not
969 yet supported.
970
Stephen Boyd0efe7292014-09-15 17:22:51 -0700971 msm_serial,<addr>
972 Start an early, polled-mode console on an msm serial
973 port at the specified address. The serial port
974 must already be setup and configured. Options are not
975 yet supported.
976
977 msm_serial_dm,<addr>
978 Start an early, polled-mode console on an msm serial
979 dm port at the specified address. The serial port
980 must already be setup and configured. Options are not
981 yet supported.
982
Rob Herringd50d7262014-04-18 17:19:58 -0500983 smh Use ARM semihosting calls for early console.
984
Tomasz Figab94ba032015-01-23 14:47:41 +0100985 s3c2410,<addr>
986 s3c2412,<addr>
987 s3c2440,<addr>
988 s3c6400,<addr>
989 s5pv210,<addr>
990 exynos4210,<addr>
991 Use early console provided by serial driver available
992 on Samsung SoCs, requires selecting proper type and
993 a correct base address of the selected UART port. The
994 serial port must already be setup and configured.
995 Options are not yet supported.
996
Finn Thain7913ad12014-04-12 23:48:56 +1000997 earlyprintk= [X86,SH,BLACKFIN,ARM,M68k]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 earlyprintk=vga
Matt Fleming72548e82013-10-04 09:36:56 +0100999 earlyprintk=efi
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -05001000 earlyprintk=xen
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 earlyprintk=serial[,ttySn[,baudrate]]
Dave Hansen147ea092013-04-10 14:03:38 -07001002 earlyprintk=serial[,0x...[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -05001003 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -05001004 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
Dave Hansen147ea092013-04-10 14:03:38 -07001006 earlyprintk is useful when the kernel crashes before
1007 the normal console is initialized. It is not enabled by
1008 default because it has some cosmetic problems.
1009
Randy Dunlapa9913042005-10-23 12:57:11 -07001010 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 takes over.
1012
Matt Fleming72548e82013-10-04 09:36:56 +01001013 Only one of vga, efi, serial, or usb debug port can
1014 be used at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015
Dave Hansen147ea092013-04-10 14:03:38 -07001016 Currently only ttyS0 and ttyS1 may be specified by
1017 name. Other I/O ports may be explicitly specified
1018 on some architectures (x86 and arm at least) by
1019 replacing ttySn with an I/O port address, like this:
1020 earlyprintk=serial,0x1008,115200
1021 You can find the port for a given device in
1022 /proc/tty/driver/serial:
1023 2: uart:ST16650V2 port:00001008 irq:18 ...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024
1025 Interaction with the standard serial driver is not
1026 very good.
1027
Matt Fleming72548e82013-10-04 09:36:56 +01001028 The VGA and EFI output is eventually overwritten by
1029 the real console.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -05001031 The xen output can only be used by Xen PV guests.
1032
Chen, Gongc700f012013-12-06 01:17:08 -05001033 edac_report= [HW,EDAC] Control how to report EDAC event
1034 Format: {"on" | "off" | "force"}
1035 on: enable EDAC to report H/W event. May be overridden
1036 by other higher priority error reporting module.
1037 off: disable H/W event reporting through EDAC.
1038 force: enforce the use of EDAC to report H/W event.
1039 default: on.
1040
Jason Wessel97311912010-05-20 21:04:30 -05001041 ekgdboc= [X86,KGDB] Allow early kernel console debugging
1042 ekgdboc=kbd
1043
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001044 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -05001045 the boot argument: earlyprintk=vga
1046
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -07001048 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001050 efi= [EFI]
Dave Young5ae36832014-08-14 17:15:28 +08001051 Format: { "old_map", "nochunk", "noruntime" }
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001052 old_map [X86-64]: switch to the old ioremap-based EFI
1053 runtime services mapping. 32-bit still uses this one by
1054 default.
Matt Fleming5a17dae2014-08-05 11:52:11 +01001055 nochunk: disable reading files in "chunks" in the EFI
1056 boot stub, as chunking can cause problems with some
1057 firmware implementations.
Dave Young5ae36832014-08-14 17:15:28 +08001058 noruntime : disable EFI runtime services support
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001059
Richard Weinberger8c58bf32013-04-17 01:00:53 +02001060 efi_no_storage_paranoia [EFI; X86]
1061 Using this parameter you can use more than 50% of
1062 your efi variable storage. Use this parameter only if
1063 you are really sure that your UEFI does sane gc and
1064 fulfills the spec otherwise your board may brick.
1065
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 eisa_irq_edge= [PARISC,HW]
1067 See header of drivers/parisc/eisa.c.
1068
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001069 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -07001071 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072
1073 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +01001074 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +02001075 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07001076 Documentation/block/deadline-iosched.txt for details.
1077
Michael Holzheud3bf37952011-10-30 15:16:37 +01001078 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -07001079 Specifies physical address of start of kernel core
Michael Holzheud3bf37952011-10-30 15:16:37 +01001080 image elf header and optionally the size. Generally
1081 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -08001082 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001084 enable_mtrr_cleanup [X86]
1085 The kernel tries to adjust MTRR layout from continuous
1086 to discrete, to make X server driver able to add WB
1087 entry later. This parameter enables that.
1088
Randy Dunlapca1eda22009-05-06 16:02:58 -07001089 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001090 Enable PIN 1 of APIC timer
1091 Can be useful to work around chipset bugs
1092 (in particular on some ATI chipsets).
1093 The kernel tries to set a reasonable default.
1094
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 enforcing [SELINUX] Set initial enforcing status.
1096 Format: {"0" | "1"}
1097 See security/selinux/Kconfig help text.
1098 0 -- permissive (log only, no denials).
1099 1 -- enforcing (deny and log).
1100 Default value is 0.
1101 Value can be changed at runtime via /selinux/enforce.
1102
Huang Yinga08f82d2010-05-18 14:35:21 +08001103 erst_disable [ACPI]
1104 Disable Error Record Serialization Table (ERST)
1105 support.
1106
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 ether= [HW,NET] Ethernet cards parameters
1108 This option is obsoleted by the "netdev=" option, which
1109 has equivalent usage. See its documentation for details.
1110
Mimi Zohar7102ebc2011-05-12 18:33:20 -04001111 evm= [EVM]
1112 Format: { "fix" }
1113 Permit 'security.evm' to be updated regardless of
1114 current integrity status.
1115
Akinobu Mitade1ba092006-12-08 02:39:42 -08001116 failslab=
1117 fail_page_alloc=
1118 fail_make_request=[KNL]
1119 General fault injection mechanism.
1120 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +02001121 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -08001122
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001124 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125
Alex Chiangf13ae302008-05-08 14:03:23 -06001126 force_pal_cache_flush
1127 [IA-64] Avoid check_sal_cache_flush which may hang on
1128 buggy SAL_CACHE_FLUSH implementations. Using this
1129 parameter will force ia64_sal_cache_flush to call
1130 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1131
Chris Bainbridge69f23662014-03-07 18:40:42 +07001132 forcepae [X86-32]
1133 Forcefully enable Physical Address Extension (PAE).
1134 Many Pentium M systems disable PAE but may have a
1135 functionally usable PAE implementation.
1136 Warning: use of this parameter will taint the kernel
1137 and may cause unknown problems.
1138
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001139 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -04001140 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001141 as early as possible in order to facilitate early
1142 boot debugging.
1143
Frederic Weisbeckercecbca92010-04-18 19:08:41 +02001144 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -04001145 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +02001146 If no parameter is passed, ftrace will dump
1147 buffers of all CPUs, but if you pass orig_cpu, it will
1148 dump only the buffer of the CPU that triggered the
1149 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -04001150
1151 ftrace_filter=[function-list]
1152 [FTRACE] Limit the functions traced by the function
1153 tracer at boot up. function-list is a comma separated
1154 list of functions. This list can be changed at run
1155 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -07001156 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -04001157
1158 ftrace_notrace=[function-list]
1159 [FTRACE] Do not trace the functions specified in
1160 function-list. This list can be changed at run time
1161 by the set_ftrace_notrace file in the debugfs
1162 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001163
Stefan Assmann369bc182009-10-12 22:17:21 +02001164 ftrace_graph_filter=[function-list]
1165 [FTRACE] Limit the top level callers functions traced
1166 by the function graph tracer at boot up.
1167 function-list is a comma separated list of functions
1168 that can be changed at run time by the
1169 set_graph_function file in the debugfs tracing directory.
1170
Namhyung Kim0d7d9a12014-06-13 01:23:50 +09001171 ftrace_graph_notrace=[function-list]
1172 [FTRACE] Do not trace from the functions specified in
1173 function-list. This list is a comma separated list of
1174 functions that can be changed at run time by the
1175 set_graph_notrace file in the debugfs tracing directory.
1176
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 gamecon.map[2|3]=
1178 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1179 support via parallel port (up to 5 devices per port)
1180 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1181 See also Documentation/input/joystick-parport.txt
1182
1183 gamma= [HW,DRM]
1184
Yinghai Luaaf23042008-01-30 13:33:09 +01001185 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
1186 Format: off | on
1187 default: on
1188
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -07001189 gcov_persist= [GCOV] When non-zero (default), profiling data for
1190 kernel modules is saved and remains accessible via
1191 debugfs, even when the module is unloaded/reloaded.
1192 When zero, profiling data is discarded and associated
1193 debugfs files are removed at module unload time.
1194
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 gpt [EFI] Forces disk with valid GPT signature but
Davidlohr Bueso6c5de792014-01-23 15:56:03 -08001196 invalid Protective MBR to be treated as GPT. If the
1197 primary GPT is corrupted, it enables the backup/alternate
1198 GPT to be used instead.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199
Andreas Larsson6cec9b02012-11-15 08:47:14 +01001200 grcan.enable0= [HW] Configuration of physical interface 0. Determines
1201 the "Enable 0" bit of the configuration register.
1202 Format: 0 | 1
1203 Default: 0
1204 grcan.enable1= [HW] Configuration of physical interface 1. Determines
1205 the "Enable 0" bit of the configuration register.
1206 Format: 0 | 1
1207 Default: 0
1208 grcan.select= [HW] Select which physical interface to use.
1209 Format: 0 | 1
1210 Default: 0
1211 grcan.txsize= [HW] Sets the size of the tx buffer.
1212 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1213 Default: 1024
1214 grcan.rxsize= [HW] Sets the size of the rx buffer.
1215 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1216 Default: 1024
1217
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 hashdist= [KNL,NUMA] Large hashes allocated during boot
1219 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -07001220 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -07001221 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222
1223 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1224
1225 hd= [EIDE] (E)IDE hard drive subsystem geometry
1226 Format: <cyl>,<head>,<sect>
1227
Huang Yingea8c0712010-05-18 14:35:15 +08001228 hest_disable [ACPI]
1229 Disable Hardware Error Source Table (HEST) support;
1230 corresponding firmware-first mode error processing
1231 logic will be disabled.
1232
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
1234 size of <nn>. This works even on boxes that have no
1235 highmem otherwise. This also works to reduce highmem
1236 size on bigger boxes.
1237
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -08001238 highres= [KNL] Enable/disable high resolution timer mode.
1239 Valid parameters: "on", "off"
1240 Default: "on"
1241
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 hisax= [HW,ISDN]
1243 See Documentation/isdn/README.HiSax.
1244
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001245 hlt [BUGS=ARM,SH]
1246
1247 hpet= [X86-32,HPET] option to control HPET usage
1248 Format: { enable (default) | disable | force |
1249 verbose }
1250 disable: disable HPET and use PIT instead
1251 force: allow force enabled of undocumented chips (ICH4,
1252 VIA, nVidia)
1253 verbose: show contents of HPET registers during setup
1254
Prarit Bhargava3d035f52013-11-12 15:08:33 -08001255 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1256 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1257
Andi Kleenb4718e62008-07-23 21:27:51 -07001258 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1259 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -07001260 On x86-64 and powerpc, this option can be specified
1261 multiple times interleaved with hugepages= to reserve
1262 huge pages of different sizes. Valid pages sizes on
1263 x86-64 are 2M (when the CPU supports "pse") and 1G
Luiz Capitulino27ec26e2014-12-12 16:55:18 -08001264 (when the CPU supports the "pdpe1gb" cpuinfo flag).
Paul Mundt6902aa82008-09-21 17:14:42 +09001265
Hendrik Brueckner555d61d2009-01-09 12:15:02 +01001266 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
1267 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +01001268 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1269 If specified, z/VM IUCV HVC accepts connections
1270 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +01001271
James Hoganfdabf522012-10-09 11:00:27 +01001272 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
1273 hardware thread id mappings.
1274 Format: <cpu>:<hwthread>
1275
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07001276 keep_bootcon [KNL]
1277 Do not unregister boot console at start. This is only
1278 useful for debugging when something happens in the window
1279 between unregistering the boot console and initializing
1280 the real console.
1281
Jarkko Nikula3a853fb2009-03-23 18:07:47 -07001282 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -07001283 or register an additional I2C bus that is not
1284 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -07001285 Format:
1286 <bus_id>,<clkrate>
1287
Jiri Kosina36d95732008-10-06 02:51:09 -04001288 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +02001290 i8042.dumbkbd [HW] Pretend that controller can only read data from
1291 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 (Don't attempt to blink the leds)
1293 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -05001294 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -04001295 i8042.noloop [HW] Disable the AUX Loopback command while probing
1296 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 i8042.nomux [HW] Don't check presence of an active multiplexing
Dmitry Torokhove55a3362014-10-31 09:35:53 -07001298 controller
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1300 controllers
Masanari Iida24775d62012-02-15 00:26:42 +09001301 i8042.notimeout [HW] Ignore timeout condition signalled by controller
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302 i8042.reset [HW] Reset the controller during init and cleanup
1303 i8042.unlock [HW] Unlock (ignore) the keylock
Srihari Vijayaraghavan148e9a72015-01-07 16:25:53 -08001304 i8042.kbdreset [HW] Reset device connected to KBD port
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
1306 i810= [HW,DRM]
1307
Dmitry Torokhove70c9d52005-06-25 14:54:25 -07001308 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1309 indicates that the driver is running on unsupported
1310 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1312 does not match list of supported models.
1313 i8k.power_status
1314 [HW] Report power status in /proc/i8k
1315 (disabled by default)
1316 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1317 capability is set.
1318
Carsten Emde4dca20e2012-03-15 15:56:26 +01001319 i915.invert_brightness=
Carsten Emde7bd90902012-03-15 15:56:25 +01001320 [DRM] Invert the sense of the variable that is used to
1321 set the brightness of the panel backlight. Normally a
Carsten Emde4dca20e2012-03-15 15:56:26 +01001322 brightness value of 0 indicates backlight switched off,
1323 and the maximum of the brightness value sets the backlight
1324 to maximum brightness. If this parameter is set to 0
1325 (default) and the machine requires it, or this parameter
1326 is set to 1, a brightness value of 0 sets the backlight
1327 to maximum brightness, and the maximum of the brightness
1328 value switches the backlight off.
1329 -1 -- never invert brightness
1330 0 -- machine default
1331 1 -- force brightness inversion
Carsten Emde7bd90902012-03-15 15:56:25 +01001332
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 icn= [HW,ISDN]
1334 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1335
David Fries0af80c02009-02-25 20:28:21 +01001336 ide-core.nodma= [HW] (E)IDE subsystem
1337 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +02001338 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1339 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +01001340 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341
Maciej W. Rozycki0f8b7f52014-10-25 17:03:52 +01001342 ide-generic.probe-mask= [HW] (E)IDE subsystem
1343 Format: <int>
1344 Probe mask for legacy ISA IDE ports. Depending on
1345 platform up to 6 ports are supported, enabled by
1346 setting corresponding bits in the mask to 1. The
1347 default value is 0x0, which has a special meaning.
1348 On systems that have PCI, it triggers scanning the
1349 PCI bus for the first and the second port, which
1350 are then probed. On systems without PCI the value
1351 of 0x0 enables probing the two first ports as if it
1352 was 0x3.
1353
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001354 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1355 Claim all unknown PCI IDE storage controllers.
1356
Andi Kleenf039b752007-05-02 19:27:12 +02001357 idle= [X86]
Len Brown69fb3672013-02-10 01:38:39 -05001358 Format: idle=poll, idle=halt, idle=nomwait
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001359 Poll forces a polling idle loop that can slightly
1360 improve the performance of waking up a idle CPU, but
1361 will use a lot of power and make the system run hot.
1362 Not recommended.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001363 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +08001364 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001365 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -07001366
Ingo Molnar792908222006-12-06 20:40:51 -08001367 ignore_loglevel [KNL]
1368 Ignore loglevel setting - this will print /all/
1369 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001370 We also add it as printk module parameter, so users
1371 could change it dynamically, usually by
1372 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -08001373
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 ihash_entries= [KNL]
1375 Set number of hash buckets for inode cache.
1376
Mimi Zohar2fe5d6d2012-02-13 10:15:05 -05001377 ima_appraise= [IMA] appraise integrity measurements
Dmitry Kasatkin2faa6ef2014-05-08 13:11:29 +03001378 Format: { "off" | "enforce" | "fix" | "log" }
Mimi Zohar2fe5d6d2012-02-13 10:15:05 -05001379 default: "enforce"
1380
Mimi Zohar07f6a792011-03-09 22:25:48 -05001381 ima_appraise_tcb [IMA]
1382 The builtin appraise policy appraises all files
1383 owned by uid=0.
1384
Mimi Zohar3323eec2009-02-04 09:06:58 -05001385 ima_hash= [IMA]
Mimi Zohare7a2ad72013-06-07 12:16:37 +02001386 Format: { md5 | sha1 | rmd160 | sha256 | sha384
1387 | sha512 | ... }
Mimi Zohar3323eec2009-02-04 09:06:58 -05001388 default: "sha1"
1389
Mimi Zohare7a2ad72013-06-07 12:16:37 +02001390 The list of supported hash algorithms is defined
1391 in crypto/hash_info.h.
1392
Eric Paris5789ba32009-05-21 15:47:06 -04001393 ima_tcb [IMA]
1394 Load a policy which meets the needs of the Trusted
1395 Computing Base. This means IMA will measure all
1396 programs exec'd, files mmap'd for exec, and all files
1397 opened for read by uid=0.
1398
Roberto Sassu9b9d4ce2013-06-07 12:16:35 +02001399 ima_template= [IMA]
1400 Select one of defined IMA measurements template formats.
1401 Formats: { "ima" | "ima-ng" }
1402 Default: "ima-ng"
1403
Roberto Sassuc2426d22014-10-13 14:08:42 +02001404 ima_template_fmt=
1405 [IMA] Define a custom template format.
1406 Format: { "field1|...|fieldN" }
1407
Dmitry Kasatkin3bcced32014-02-26 17:05:20 +02001408 ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1409 Format: <min_file_size>
1410 Set the minimal file size for using asynchronous hash.
1411 If left unspecified, ahash usage is disabled.
1412
1413 ahash performance varies for different data sizes on
1414 different crypto accelerators. This option can be used
1415 to achieve the best performance for a particular HW.
1416
Dmitry Kasatkin6edf7a82014-05-06 14:47:13 +03001417 ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1418 Format: <bufsize>
1419 Set hashing buffer size. Default: 4k.
1420
1421 ahash performance varies for different chunk sizes on
1422 different crypto accelerators. This option can be used
1423 to achieve best performance for particular HW.
1424
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 init= [KNL]
1426 Format: <full_path>
1427 Run specified binary instead of /sbin/init as init
1428 process.
1429
1430 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1431 for working out where the kernel is dying during
1432 startup.
1433
Prarit Bhargava7b0b73d2014-06-04 16:12:17 -07001434 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1435 initcall functions. Useful for debugging built-in
1436 modules and initcalls.
1437
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 initrd= [BOOT] Specify the location of the initial ramdisk
1439
1440 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1441 Format: <irq>
1442
Fenghua Yu6bb2ff82013-05-21 15:35:17 -04001443 int_pln_enable [x86] Enable power limit notification interrupt
1444
Mimi Zohard726d8d2013-03-18 14:48:02 -04001445 integrity_audit=[IMA]
1446 Format: { "0" | "1" }
1447 0 -- basic integrity auditing messages. (Default)
1448 1 -- additional integrity auditing messages.
1449
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001450 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001451 on
1452 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001453 off
1454 Disable intel iommu driver.
1455 igfx_off [Default Off]
1456 By default, gfx is mapped as normal device. If a gfx
1457 device has a dedicated DMAR unit, the DMAR unit is
1458 bypassed by not enabling DMAR with this option. In
1459 this case, gfx device will use physical address for
1460 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001461 forcedac [x86_64]
1462 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001463 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001464 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001465 than 32-bit addressing. The default is to look
1466 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001467 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001468 strict [Default Off]
1469 With this option on every unmap_single operation will
1470 result in a hardware IOTLB flush operation as opposed
1471 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001472 sp_off [Default Off]
1473 By default, super page will be supported if Intel IOMMU
1474 has the capability. With this option, super page will
1475 not be supported.
Masanari Iida2e92c7a2011-12-15 01:18:52 +09001476
1477 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1478 0 disables intel_idle and fall back on acpi_idle.
1479 1 to 6 specify maximum depth of C-state.
1480
Dirk Brandewie6be26492013-02-15 22:55:10 +01001481 intel_pstate= [X86]
1482 disable
1483 Do not enable intel_pstate as the default
1484 scaling driver for the supported processors
Ethan Zhaoaa4ea342014-12-09 10:43:19 +09001485 force
1486 Enable intel_pstate on systems that prohibit it by default
1487 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1488 instead of acpi-cpufreq may disable platform features, such
1489 as thermal controls and power capping, that rely on ACPI
1490 P-States information being indicated to OSPM and therefore
1491 should be used with caution. This option does not work with
1492 processors that aren't supported by the intel_pstate driver
1493 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
Dirk Brandewie2f86dc42014-11-06 09:40:47 -08001494 no_hwp
1495 Do not enable hardware P state control (HWP)
1496 if available.
Kristen Carlson Accardid64c3b02015-02-06 13:41:55 -08001497 hwp_only
1498 Only load intel_pstate on systems which support
1499 hardware P state control (HWP) if available.
Dirk Brandewie6be26492013-02-15 22:55:10 +01001500
Chris Wrightd1423d52010-07-20 11:06:49 -07001501 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001502 on enable Interrupt Remapping (default)
1503 off disable Interrupt Remapping
1504 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001505 no_x2apic_optout
1506 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001507
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001508 iomem= Disable strict checking of access to MMIO memory
1509 strict regions from userspace.
1510 relaxed
1511
1512 iommu= [x86]
1513 off
1514 force
1515 noforce
1516 biomerge
1517 panic
1518 nopanic
1519 merge
1520 nomerge
1521 forcesac
1522 soft
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001523 pt [x86, IA-64]
Thadeu Lima de Souza Cascardo4e287842014-10-23 19:19:35 -02001524 nobypass [PPC/POWERNV]
1525 Disable IOMMU bypass, using IOMMU for PCI devices.
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001526
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001527
1528 io7= [HW] IO7 for Marvel based alpha systems
1529 See comment before marvel_specify_io7 in
1530 arch/alpha/kernel/core_marvel.c.
1531
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301532 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001533 0x80
1534 Standard port 0x80 based delay
1535 0xed
1536 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001537 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001538 Simple two microseconds delay
1539 none
1540 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001541
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001543 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544
Alan Cox200803d2005-06-28 20:45:18 -07001545 irqfixup [HW]
1546 When an interrupt is not handled search all handlers
1547 for it. Intended to get systems with badly broken
1548 firmware running.
1549
1550 irqpoll [HW]
1551 When an interrupt is not handled search all handlers
1552 for it. Also check all handlers each timer
1553 interrupt. Intended to get systems with badly broken
1554 firmware running.
1555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001557 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558
1559 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001560 Format:
1561 <cpu number>,...,<cpu number>
1562 or
Li Zefanb225d442008-11-06 12:53:39 -08001563 <cpu number>-<cpu number>
1564 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001565 or a mixture
1566 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001567
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 This option can be used to specify one or more CPUs
1569 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001570 algorithms. You can move a process onto or off an
1571 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 <cpu number> begins at 0 and the maximum value is
1573 "number of CPUs in system - 1".
1574
1575 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001576 alternative -- manually setting the CPU mask of all
1577 tasks in the system -- can cause problems and
1578 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
Randy Dunlapa9913042005-10-23 12:57:11 -07001580 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581
Joerg Roedel7d8bfa22013-04-09 21:27:19 +02001582 ivrs_ioapic [HW,X86_64]
1583 Provide an override to the IOAPIC-ID<->DEVICE-ID
1584 mapping provided in the IVRS ACPI table. For
1585 example, to map IOAPIC-ID decimal 10 to
1586 PCI device 00:14.0 write the parameter as:
1587 ivrs_ioapic[10]=00:14.0
1588
1589 ivrs_hpet [HW,X86_64]
1590 Provide an override to the HPET-ID<->DEVICE-ID
1591 mapping provided in the IVRS ACPI table. For
1592 example, to map HPET-ID decimal 0 to
1593 PCI device 00:14.0 write the parameter as:
1594 ivrs_hpet[0]=00:14.0
1595
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 js= [HW,JOY] Analog joystick
1597 See Documentation/input/joystick.txt.
1598
Kees Cook24f2e022014-06-13 13:30:36 -07001599 kaslr/nokaslr [X86]
1600 Enable/disable kernel and module base offset ASLR
1601 (Address Space Layout Randomization) if built into
1602 the kernel. When CONFIG_HIBERNATION is selected,
1603 kASLR is disabled by default. When kASLR is enabled,
1604 hibernation will be disabled.
1605
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001606 keepinitrd [HW,ARM]
1607
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301608 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001609 specifies the amount of memory usable by the kernel
1610 for non-movable allocations. The requested amount is
1611 spread evenly throughout all nodes in the system. The
1612 remaining memory in each node is used for Movable
1613 pages. In the event, a node is too small to have both
1614 kernelcore and Movable pages, kernelcore pages will
1615 take priority and other nodes will have a larger number
Weiping Pan675217f2013-09-30 13:45:10 -07001616 of Movable pages. The Movable zone is used for the
Mel Gormaned7ed362007-07-17 04:03:14 -07001617 allocation of pages that may be reclaimed or moved
1618 by the page migration subsystem. This means that
1619 HugeTLB pages may not be allocated from this zone.
1620 Note that allocations like PTEs-from-HighMem still
1621 use the HighMem zone if it exists, and the Normal
1622 zone if it does not.
1623
Jason Wessel4fe1da42010-05-20 21:04:31 -05001624 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1625 Format: <Controller#>[,poll interval]
1626 The controller # is the number of the ehci usb debug
1627 port as it is probed via PCI. The poll interval is
1628 optional and is the number seconds in between
1629 each poll cycle to the debug port in case you need
1630 the functionality for interrupting the kernel with
1631 gdb or control-c on the dbgp connection. When
1632 not using this parameter you use sysrq-g to break into
1633 the kernel debugger.
1634
Jason Wessel84c08fd2010-05-20 21:04:24 -05001635 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001636 Requires a tty driver that supports console polling,
1637 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001638 Serial only format: <serial_device>[,baud]
1639 keyboard only format: kbd
1640 keyboard and serial format: kbd,<serial_device>[,baud]
1641 Optional Kernel mode setting:
1642 kms, kbd format: kms,kbd
1643 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001644
Jason Wessel84c08fd2010-05-20 21:04:24 -05001645 kgdbwait [KGDB] Stop kernel execution and enter the
1646 kernel debugger at the earliest opportunity.
1647
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001648 kmac= [MIPS] korina ethernet MAC address.
1649 Configure the RouterBoard 532 series on-chip
1650 Ethernet adapter MAC address.
1651
Catalin Marinas04f70332009-06-11 13:22:39 +01001652 kmemleak= [KNL] Boot-time kmemleak enable/disable
1653 Valid arguments: on, off
1654 Default: on
Masanari Iida47aeedd2014-10-24 21:24:59 +09001655 Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
1656 the default is off.
Catalin Marinas04f70332009-06-11 13:22:39 +01001657
Xishi Qiuc3ac14b2014-01-23 15:53:33 -08001658 kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode
1659 Valid arguments: 0, 1, 2
1660 kmemcheck=0 (disabled)
1661 kmemcheck=1 (enabled)
1662 kmemcheck=2 (one-shot mode)
1663 Default: 2 (one-shot mode)
1664
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301665 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001666 in oops dumps.
1667
Andre Przywarafef07aa2009-07-10 14:20:35 +02001668 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1669 Default is 0 (don't ignore, but inject #GP)
1670
Xiao Guangronga182d872010-09-20 22:17:48 +08001671 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1672 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001673 Default is 0 (off)
1674
Andre Przywarafef07aa2009-07-10 14:20:35 +02001675 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001676 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001677
1678 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1679 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001680 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001681
Andre Przywarafef07aa2009-07-10 14:20:35 +02001682 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1683 (virtualized MMU) support on capable Intel chips.
1684 Default is 1 (enabled)
1685
1686 kvm-intel.emulate_invalid_guest_state=
1687 [KVM,Intel] Enable emulation of invalid guest states
1688 Default is 0 (disabled)
1689
1690 kvm-intel.flexpriority=
1691 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1692 Default is 1 (enabled)
1693
Sasha Levine1a72ae2011-08-09 14:28:35 +03001694 kvm-intel.nested=
1695 [KVM,Intel] Enable VMX nesting (nVMX).
1696 Default is 0 (disabled)
1697
Andre Przywarafef07aa2009-07-10 14:20:35 +02001698 kvm-intel.unrestricted_guest=
1699 [KVM,Intel] Disable unrestricted guest feature
1700 (virtualized real and unpaged mode) on capable
1701 Intel chips. Default is 1 (enabled)
1702
1703 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1704 feature (tagged TLBs) on capable Intel chips.
1705 Default is 1 (enabled)
1706
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 l2cr= [PPC]
1708
Robert Brosea78bfbf2008-03-29 07:20:23 +11001709 l3cr= [PPC]
1710
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001711 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001712 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713
Suresh Siddha279f1462012-10-22 14:37:58 -07001714 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1715 value for LAPIC timer one-shot implementation. Default
1716 back to the programmable timer unit in the LAPIC.
1717
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301718 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001719 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001720
FD Camifcb71f62008-01-06 19:08:56 +01001721 libata.dma= [LIBATA] DMA control
1722 libata.dma=0 Disable all PATA and SATA DMA
1723 libata.dma=1 PATA and SATA Disk DMA only
1724 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001725 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001726 Combinations also work, so libata.dma=3 enables DMA
1727 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001728
Michael Prokop20308872009-08-06 00:14:10 +02001729 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1730 libata.ignore_hpa=0 keep BIOS limits (default)
1731 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001732
Dave Jones78e70c22007-09-27 11:50:13 -04001733 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1734 when set.
1735 Format: <int>
1736
Tejun Heo33267322008-02-13 09:15:09 +09001737 libata.force= [LIBATA] Force configurations. The format is comma
1738 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001739 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001740 matching port, link or device. Basically, it matches
1741 the ATA ID string printed on console by libata. If
1742 the whole ID part is omitted, the last PORT and DEVICE
1743 values are used. If ID hasn't been specified yet, the
1744 configuration applies to all ports, links and devices.
1745
1746 If only DEVICE is omitted, the parameter applies to
1747 the port and all links and devices behind it. DEVICE
1748 number of 0 either selects the first device or the
1749 first fan-out link behind PMP device. It does not
1750 select the host link. DEVICE number of 15 selects the
1751 host link and device attached to it.
1752
1753 The VAL specifies the configuration to force. As long
1754 as there's no ambiguity shortcut notation is allowed.
1755 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1756 The following configurations can be forced.
1757
1758 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1759 Any ID with matching PORT is used.
1760
1761 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1762
1763 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1764 udma[/][16,25,33,44,66,100,133] notation is also
1765 allowed.
1766
1767 * [no]ncq: Turn on or off NCQ.
1768
Tejun Heo05944bd2008-08-13 20:19:09 +09001769 * nohrst, nosrst, norst: suppress hard, soft
1770 and both resets.
1771
Dan Williamsca6d43b2012-06-21 23:41:41 -07001772 * rstonce: only attempt one reset during
1773 hot-unplug link recovery
1774
Tejun Heo43c9c592010-05-23 12:59:11 +02001775 * dump_id: dump IDENTIFY data.
1776
Vincent Pelletier966fbe12013-05-21 22:30:58 +02001777 * atapi_dmadir: Enable ATAPI DMADIR bridge support
1778
Robin H. Johnsonb8bd6dc2013-12-16 09:31:19 -08001779 * disable: Disable this device.
1780
Tejun Heo33267322008-02-13 09:15:09 +09001781 If there are multiple matching configurations changing
1782 the same attribute, the last one is used.
1783
Yinghai Lu95f72d12010-07-12 14:36:09 +10001784 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001785
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001787 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001789 lockd.nlm_grace_period=P [NFS] Assign grace period.
1790 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001792 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1793 Format: <integer>
1794
1795 lockd.nlm_timeout=T [NFS] Assign timeout value.
1796 Format: <integer>
1797
1798 lockd.nlm_udpport=M [NFS] Assign UDP port.
1799 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800
Paul E. McKenneyec4518a2014-09-12 10:50:01 -07001801 locktorture.nreaders_stress= [KNL]
1802 Set the number of locking read-acquisition kthreads.
1803 Defaults to being automatically set based on the
1804 number of online CPUs.
1805
1806 locktorture.nwriters_stress= [KNL]
1807 Set the number of locking write-acquisition kthreads.
1808
1809 locktorture.onoff_holdoff= [KNL]
1810 Set time (s) after boot for CPU-hotplug testing.
1811
1812 locktorture.onoff_interval= [KNL]
1813 Set time (s) between CPU-hotplug operations, or
1814 zero to disable CPU-hotplug testing.
1815
1816 locktorture.shuffle_interval= [KNL]
1817 Set task-shuffle interval (jiffies). Shuffling
1818 tasks allows some CPUs to go into dyntick-idle
1819 mode during the locktorture test.
1820
1821 locktorture.shutdown_secs= [KNL]
1822 Set time (s) after boot system shutdown. This
1823 is useful for hands-off automated testing.
1824
1825 locktorture.stat_interval= [KNL]
1826 Time (s) between statistics printk()s.
1827
1828 locktorture.stutter= [KNL]
1829 Time (s) to stutter testing, for example,
1830 specifying five seconds causes the test to run for
1831 five seconds, wait for five seconds, and so on.
1832 This tests the locking primitive's ability to
1833 transition abruptly to and from idle.
1834
1835 locktorture.torture_runnable= [BOOT]
1836 Start locktorture running at boot time.
1837
1838 locktorture.torture_type= [KNL]
1839 Specify the locking implementation to test.
1840
1841 locktorture.verbose= [KNL]
1842 Enable additional printk() statements.
1843
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1845 Format: <irq>
1846
1847 loglevel= All Kernel Messages with a loglevel smaller than the
1848 console loglevel will be printed to the console. It can
1849 also be changed with klogd or other programs. The
1850 loglevels are defined as follows:
1851
1852 0 (KERN_EMERG) system is unusable
1853 1 (KERN_ALERT) action must be taken immediately
1854 2 (KERN_CRIT) critical conditions
1855 3 (KERN_ERR) error conditions
1856 4 (KERN_WARNING) warning conditions
1857 5 (KERN_NOTICE) normal but significant condition
1858 6 (KERN_INFO) informational
1859 7 (KERN_DEBUG) debug-level messages
1860
Randy Dunlapc756d082011-02-20 20:08:35 -08001861 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
Luis R. Rodriguez23b28992014-08-06 16:08:56 -07001862 in bytes. n must be a power of two and greater
1863 than the minimal size. The minimal size is defined
1864 by LOG_BUF_SHIFT kernel config parameter. There is
1865 also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
1866 that allows to increase the default size depending on
1867 the number of CPUs. See init/Kconfig for more details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868
Randy Dunlapaccaa242007-10-16 01:29:37 -07001869 logo.nologo [FB] Disables display of the built-in Linux logo.
1870 This may be used to provide more screen space for
1871 kernel log messages and is useful when debugging
1872 kernel boot problems.
1873
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 lp=0 [LP] Specify parallel ports to use, e.g,
1875 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1876 lp=reset first parallel port). 'lp=0' disables the
1877 lp=auto printer driver. 'lp=reset' (which can be
1878 specified in addition to the ports) causes
1879 attached printers to be reset. Using
1880 lp=port1,port2,... specifies the parallel ports
1881 to associate lp devices with, starting with
1882 lp0. A port specification may be 'none' to skip
1883 that lp device, or a parport name such as
1884 'parport0'. Specifying 'lp=auto' instead of a
1885 port specification list means that device IDs
1886 from each port should be examined, to see if
1887 an IEEE 1284-compliant printer is attached; if
1888 so, the driver will manage that printer.
1889 See also header of drivers/char/lp.c.
1890
1891 lpj=n [KNL]
1892 Sets loops_per_jiffy to given constant, thus avoiding
1893 time-consuming boot-time autodetection (up to 250 ms per
1894 CPU). 0 enables autodetection (default). To determine
1895 the correct value for your kernel, boot with normal
1896 autodetection and see what value is printed. Note that
1897 on SMP systems the preset will be applied to all CPUs,
1898 which is likely to cause problems if your CPUs need
1899 significantly divergent settings. An incorrect value
1900 will cause delays in the kernel to be wrong, leading to
1901 unpredictable I/O errors and other breakage. Although
1902 unlikely, in the extreme case this might damage your
1903 hardware.
1904
1905 ltpc= [NET]
1906 Format: <io>,<irq>,<dma>
1907
Randy Dunlap16290242011-08-13 12:34:52 -07001908 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001909 (machvec) in a generic kernel.
1910 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911
Wu Zhangjin3209e702009-07-02 23:27:12 +08001912 machtype= [Loongson] Share the same kernel image file between different
1913 yeeloong laptop.
1914 Example: machtype=lemote-yeeloong-2f-7inch
1915
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001916 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1917 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918
1919 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001920 should make use of. maxcpus=n : n >= 0 limits the
1921 kernel to using 'n' processors. n=0 is a special case,
1922 it is equivalent to "nosmp", which also disables
1923 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924
Kay Sieversd134b002011-07-31 22:08:04 +02001925 max_loop= [LOOP] The number of loop block devices that get
1926 (loop.max_loop) unconditionally pre-created at init time. The default
1927 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1928 of statically allocating a predefined number, loop
1929 devices can be requested on-demand with the
1930 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001931
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001932 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933
Uwe Hermann71cced62008-10-20 09:32:21 -07001934 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001935
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 md= [HW] RAID subsystems devices and level
1937 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001938
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 mdacon= [MDA]
1940 Format: <first>,<last>
1941 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001942
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1944 Amount of memory to be used when the kernel is not able
1945 to see the whole system memory or for test.
Wen Congyangfbb97d82012-12-17 15:59:29 -08001946 [X86] Work as limiting max address. Use together
1947 with memmap= to avoid physical address space collisions.
1948 Without memmap= PCI devices could be placed at addresses
1949 belonging to unused RAM.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001950
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001951 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 memory.
1953
Paul Mundt6902aa82008-09-21 17:14:42 +09001954 memchunk=nn[KMG]
1955 [KNL,SH] Allow user to override the default size for
1956 per-device physically contiguous DMA buffers.
1957
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301958 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959 E820 memory map, as specified by the user.
1960 Such memmap=exactmap lines can be constructed based on
1961 BIOS output or other requirements. See the memmap=nn@ss
1962 option description.
1963
1964 memmap=nn[KMG]@ss[KMG]
Randy Dunlap277cba12014-02-06 12:04:19 -08001965 [KNL] Force usage of a specific region of memory.
1966 Region of memory to be used is from ss to ss+nn.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967
1968 memmap=nn[KMG]#ss[KMG]
1969 [KNL,ACPI] Mark specific memory as ACPI data.
Randy Dunlap277cba12014-02-06 12:04:19 -08001970 Region of memory to be marked is from ss to ss+nn.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971
1972 memmap=nn[KMG]$ss[KMG]
1973 [KNL,ACPI] Mark specific memory as reserved.
Randy Dunlap277cba12014-02-06 12:04:19 -08001974 Region of memory to be reserved is from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001975 Example: Exclude memory from 0x18690000-0x1869ffff
1976 memmap=64K$0x18690000
1977 or
1978 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001980 memory_corruption_check=0/1 [X86]
1981 Some BIOSes seem to corrupt the first 64k of
1982 memory when doing things like suspend/resume.
1983 Setting this option will scan the memory
1984 looking for corruption. Enabling this will
1985 both detect corruption and prevent the kernel
1986 from using the memory being corrupted.
1987 However, its intended as a diagnostic tool; if
1988 repeatable BIOS-originated corruption always
1989 affects the same memory, you can use memmap=
1990 to prevent the kernel from using that memory.
1991
1992 memory_corruption_check_size=size [X86]
1993 By default it checks for corruption in the low
1994 64k, making this memory unavailable for normal
1995 use. Use this parameter to scan for
1996 corruption in more or less memory.
1997
1998 memory_corruption_check_period=seconds [X86]
1999 By default it checks for corruption every 60
2000 seconds. Use this parameter to check at some
2001 other rate. 0 disables periodic checking.
2002
Yinghai Lucaadbdc2008-07-15 00:03:44 -07002003 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07002004 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07002005 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01002006 Specifies the number of memtest passes to be
2007 performed. Each pass selects another test
2008 pattern from a given set of patterns. Memtest
2009 fills the memory with this pattern, validates
2010 memory contents and reserves bad memory
2011 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07002012
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013 meye.*= [HW] Set MotionEye Camera parameters
2014 See Documentation/video4linux/meye.txt.
2015
Andres Salomon8f368812007-10-12 23:04:06 +02002016 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2017 Multi-Function General Purpose Timers on AMD Geode
2018 platforms.
2019
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01002020 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2021 the BIOS has incorrectly applied a workaround. TinyBIOS
2022 version 0.98 is known to be affected, 0.99 fixes the
2023 problem by letting the user disable the workaround.
2024
Linus Torvalds1da177e2005-04-16 15:20:36 -07002025 mga= [HW,DRM]
2026
Randy Dunlap1c207f952008-11-19 15:36:16 -08002027 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
2028 physical address is ignored.
2029
Michel Pollet39f45d72009-05-20 11:10:31 +01002030 mini2440= [ARM,HW,KNL]
2031 Format:[0..2][b][c][t]
2032 Default: "0tb"
2033 MINI2440 configuration specification:
2034 0 - The attached screen is the 3.5" TFT
2035 1 - The attached screen is the 7" TFT
2036 2 - The VGA Shield is attached (1024x768)
2037 Leaving out the screen size parameter will not load
2038 the TFT driver, and the framebuffer will be left
2039 unconfigured.
2040 b - Enable backlight. The TFT backlight pin will be
2041 linked to the kernel VESA blanking code and a GPIO
2042 LED. This parameter is not necessary when using the
2043 VGA shield.
2044 c - Enable the s3c camera interface.
2045 t - Reserved for enabling touchscreen support. The
2046 touchscreen support is not enabled in the mainstream
2047 kernel as of 2.6.30, a preliminary port can be found
2048 in the "bleeding edge" mini2440 support kernel at
2049 http://repo.or.cz/w/linux-2.6/mini2440.git
2050
Mel Gorman6b74ab92008-07-23 21:26:49 -07002051 mminit_loglevel=
2052 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2053 parameter allows control of the logging verbosity for
2054 the additional memory initialisation checks. A value
2055 of 0 disables mminit logging and a level of 4 will
2056 log everything. Information is printed at KERN_DEBUG
2057 so loglevel=8 may also need to be specified.
2058
Rusty Russell106a4ee2012-09-26 10:09:40 +01002059 module.sig_enforce
2060 [KNL] When CONFIG_MODULE_SIG is set, this means that
2061 modules without (valid) signatures will fail to load.
Paul Bolle2a039be2013-03-25 20:42:06 +01002062 Note that if CONFIG_MODULE_SIG_FORCE is set, that
Rusty Russell106a4ee2012-09-26 10:09:40 +01002063 is always true, so this option does nothing.
2064
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 mousedev.tap_time=
2066 [MOUSE] Maximum time between finger touching and
2067 leaving touchpad surface for touch to be considered
2068 a tap and be reported as a left button click (for
2069 touchpads working in absolute mode only).
2070 Format: <msecs>
2071 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
2072 reporting absolute coordinates, such as tablets
2073 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
2074 reporting absolute coordinates, such as tablets
2075
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302076 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002077 is similar to kernelcore except it specifies the
2078 amount of memory used for migratable allocations.
2079 If both kernelcore and movablecore is specified,
2080 then kernelcore will be at *least* the specified
2081 value but may be more. If movablecore on its own
2082 is specified, the administrator must be careful
2083 that the amount of memory usable for all allocations
2084 is not too small.
2085
Tang Chenc5320922013-11-12 15:08:10 -08002086 movable_node [KNL,X86] Boot-time switch to enable the effects
2087 of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
2088
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 MTD_Partition= [MTD]
2090 Format: <name>,<region-number>,<size>,<offset>
2091
Randy Dunlapa9913042005-10-23 12:57:11 -07002092 MTD_Region= [MTD] Format:
2093 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094
2095 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07002096 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097
Will Schmidt4e89a2d2010-09-28 15:33:12 +00002098 multitce=off [PPC] This parameter disables the use of the pSeries
2099 firmware feature for updating multiple TCE entries
2100 at a time.
2101
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07002102 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
2103
2104 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2105
2106 boundary - index of last SLC block on Flex-OneNAND.
2107 The remaining blocks are configured as MLC blocks.
2108 lock - Configure if Flex-OneNAND boundary should be locked.
2109 Once locked, the boundary cannot be changed.
2110 1 indicates lock status, 0 indicates unlock status.
2111
Ben Dooks9db829f2008-07-03 11:24:29 +01002112 mtdset= [ARM]
2113 ARM/S3C2412 JIVE boot control
2114
2115 See arch/arm/mach-s3c2412/mach-jive.c
2116
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07002118 [HW] Make the MicroTouch USB driver use raw coordinates
2119 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002121 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02002122 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002123 that could hold holes aka. UC entries.
2124
2125 mtrr_gran_size=nn[KMG] [X86]
2126 Used for mtrr cleanup. It is granularity of mtrr block.
2127 Default is 1.
2128 Large value could prevent small alignment from
2129 using up MTRRs.
2130
2131 mtrr_spare_reg_nr=n [X86]
2132 Format: <integer>
2133 Range: 0,7 : spare reg number
2134 Default : 1
2135 Used for mtrr cleanup. It is spare mtrr entries number.
2136 Set to 2 or more if your graphical card needs more.
2137
Linus Torvalds1da177e2005-04-16 15:20:36 -07002138 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
2139
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 netdev= [NET] Network devices parameters
2141 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2142 Note that mem_start is often overloaded to mean
2143 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07002144 This usage is only documented in each driver source
2145 file if at all.
2146
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07002147 nf_conntrack.acct=
2148 [NETFILTER] Enable connection tracking flow accounting
2149 0 to disable accounting
2150 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02002151 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07002152
Chuck Lever306a0752010-09-17 10:54:37 -04002153 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04002154 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155
2156 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04002157 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158
Chuck Lever306a0752010-09-17 10:54:37 -04002159 nfsrootdebug [NFS] enable nfsroot debugging messages.
2160 See Documentation/filesystems/nfs/nfsroot.txt.
2161
Trond Myklebusta72b4422006-01-03 09:55:41 +01002162 nfs.callback_tcpport=
2163 [NFS] set the TCP port on which the NFSv4 callback
2164 channel should listen.
2165
Trond Myklebuste571cbf2009-08-19 18:12:27 -04002166 nfs.cache_getent=
2167 [NFS] sets the pathname to the program which is used
2168 to update the NFS client cache entries.
2169
2170 nfs.cache_getent_timeout=
2171 [NFS] sets the timeout after which an attempt to
2172 update a cache entry is deemed to have failed.
2173
Trond Myklebust58df0952006-01-03 09:55:57 +01002174 nfs.idmap_cache_timeout=
2175 [NFS] set the maximum lifetime for idmapper cache
2176 entries.
2177
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04002178 nfs.enable_ino64=
2179 [NFS] enable 64-bit inode numbers.
2180 If zero, the NFS client will fake up a 32-bit inode
2181 number for the readdir() and stat() syscalls instead
2182 of returning the full 64-bit number.
2183 The default is to return 64-bit inode numbers.
2184
Trond Myklebustef159e92012-02-06 19:50:40 -05002185 nfs.max_session_slots=
2186 [NFSv4.1] Sets the maximum number of session slots
2187 the client will attempt to negotiate with the server.
2188 This limits the number of simultaneous RPC requests
2189 that the client can send to the NFSv4.1 server.
2190 Note that there is little point in setting this
2191 value higher than the max_tcp_slot_table_limit.
2192
Trond Myklebustb064eca22011-02-22 15:44:32 -08002193 nfs.nfs4_disable_idmapping=
Trond Myklebust074b1d12012-01-09 13:46:26 -05002194 [NFSv4] When set to the default of '1', this option
2195 ensures that both the RPC level authentication
2196 scheme and the NFS level operations agree to use
2197 numeric uids/gids if the mount is using the
2198 'sec=sys' security flavour. In effect it is
2199 disabling idmapping, which can make migration from
2200 legacy NFSv2/v3 systems to NFSv4 easier.
2201 Servers that do not support this mode of operation
2202 will be autodetected by the client, and it will fall
2203 back to using the idmapper.
2204 To turn off this behaviour, set the value to '0'.
Chuck Lever6f2ea7f2012-09-14 17:24:41 -04002205 nfs.nfs4_unique_id=
2206 [NFS4] Specify an additional fixed unique ident-
2207 ification string that NFSv4 clients can insert into
2208 their nfs_client_id4 string. This is typically a
2209 UUID that is generated at system install time.
Trond Myklebustb064eca22011-02-22 15:44:32 -08002210
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002211 nfs.send_implementation_id =
2212 [NFSv4.1] Send client implementation identification
2213 information in exchange_id requests.
2214 If zero, no implementation identification information
2215 will be sent.
2216 The default is to send the implementation identification
2217 information.
Trond Myklebustf6de7a32013-09-04 10:08:54 -04002218
2219 nfs.recover_lost_locks =
2220 [NFSv4] Attempt to recover locks that were lost due
2221 to a lease timeout on the server. Please note that
2222 doing this risks data corruption, since there are
2223 no guarantees that the file will remain unchanged
2224 after the locks are lost.
2225 If you want to enable the kernel legacy behaviour of
2226 attempting to recover these locks, then set this
2227 parameter to '1'.
2228 The default parameter value of '0' causes the kernel
2229 not to attempt recovery of lost locks.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002230
J. Bruce Fieldse9541ce2012-03-22 16:07:18 -04002231 nfsd.nfs4_disable_idmapping=
2232 [NFSv4] When set to the default of '1', the NFSv4
2233 server will return only numeric uids and gids to
2234 clients using auth_sys, and will accept numeric uids
2235 and gids from such clients. This is intended to ease
2236 migration from NFSv2/v3.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002237
Sachin Bhamare18d98f62012-03-19 20:47:58 -07002238 objlayoutdriver.osd_login_prog=
2239 [NFS] [OBJLAYOUT] sets the pathname to the program which
2240 is used to automatically discover and login into new
2241 osd-targets. Please see:
2242 Documentation/filesystems/pnfs.txt for more explanations
2243
Paul Mundt1e1030d2009-09-01 17:38:32 +09002244 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02002245 when a NMI is triggered.
2246 Format: [state][,regs][,debounce][,die]
2247
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302248 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07002249 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05002250 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03002251 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002252 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07002253 timeout occurs (or 'nopanic' to override the opposite
2254 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002255 This is useful when you use a panic=... timeout and
2256 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257
Anton Vorontsovbff38772009-07-08 11:10:56 -07002258 netpoll.carrier_timeout=
2259 [NET] Specifies amount of time (in seconds) that
2260 netpoll should wait for a carrier. By default netpoll
2261 waits 4 seconds.
2262
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002263 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 emulation library even if a 387 maths coprocessor
2265 is present.
2266
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002267 no_console_suspend
2268 [HW] Never suspend the console
2269 Disable suspending of consoles during suspend and
2270 hibernate operations. Once disabled, debugging
2271 messages can reach various consoles while the rest
2272 of the system is being put to sleep (ie, while
2273 debugging driver suspend/resume hooks). This may
2274 not work reliably with all consoles, but is known
2275 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07002276 To facilitate more flexible debugging, we also add
2277 console_suspend, a printk module parameter to control
2278 it. Users could use console_suspend (usually
2279 /sys/module/printk/parameters/console_suspend) to
2280 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002281
Christoph Lameterc1aee212007-05-31 00:40:47 -07002282 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
2283 caches in the slab allocator. Saves per-node memory,
2284 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08002285
Randy Dunlapa9913042005-10-23 12:57:11 -07002286 noalign [KNL,ARM]
2287
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288 noapic [SMP,APIC] Tells the kernel to not make use of any
2289 IOAPICs that may be present in the system.
2290
Mike Galbraith5091faa2010-11-30 14:18:03 +01002291 noautogroup Disable scheduler automatic task group creation.
2292
Linus Torvalds1da177e2005-04-16 15:20:36 -07002293 nobats [PPC] Do not use BATs for mapping kernel lowmem
2294 on "Classic" PPC cores.
2295
2296 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07002297
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002298 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
2299
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07002300 nodelayacct [KNL] Disable per-task delay accounting
2301
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
2303
Paul Mundt6902aa82008-09-21 17:14:42 +09002304 nodsp [SH] Disable hardware DSP at boot time.
2305
Dave Youngb2e0a542014-08-14 17:15:26 +08002306 noefi Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01002307
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 noexec [IA-64]
2309
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302310 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002311 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002313 noexec=off: disable non-executable mappings
2314
H. Peter Anvin52b61792012-09-21 12:43:13 -07002315 nosmap [X86]
2316 Disable SMAP (Supervisor Mode Access Prevention)
2317 even if it is supported by processor.
2318
Fenghua Yude5397a2011-05-11 16:51:05 -07002319 nosmep [X86]
H. Peter Anvin52b61792012-09-21 12:43:13 -07002320 Disable SMEP (Supervisor Mode Execution Prevention)
Fenghua Yude5397a2011-05-11 16:51:05 -07002321 even if it is supported by processor.
2322
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002323 noexec32 [X86-64]
2324 This affects only 32-bit executables.
2325 noexec32=on: enable non-executable mappings (default)
2326 read doesn't imply executable mappings
2327 noexec32=off: disable non-executable mappings
2328 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329
Paul Mundt6902aa82008-09-21 17:14:42 +09002330 nofpu [SH] Disable hardware FPU at boot time.
2331
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002332 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08002333 register save and restore. The kernel will only save
2334 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002335
Suresh Siddha0c752a92009-05-22 12:17:45 -07002336 noxsave [BUGS=X86] Disables x86 extended register state save
2337 and restore using xsave. The kernel will fallback to
2338 enabling legacy floating-point and sse state.
2339
Fenghua Yub6f42a42014-05-29 11:12:31 -07002340 noxsaveopt [X86] Disables xsaveopt used in saving x86 extended
2341 register states. The kernel will fall back to use
2342 xsave to save the states. By using this parameter,
2343 performance of saving the states is degraded because
2344 xsave doesn't support modified optimization while
2345 xsaveopt supports it on xsaveopt enabled systems.
2346
2347 noxsaves [X86] Disables xsaves and xrstors used in saving and
2348 restoring x86 extended register state in compacted
2349 form of xsave area. The kernel will fall back to use
2350 xsaveopt and xrstor to save and restore the states
2351 in standard form of xsave area. By using this
2352 parameter, xsave area per process might occupy more
2353 memory on xsaves enabled systems.
2354
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002355 eagerfpu= [X86]
Suresh Siddhae0022982012-09-10 10:32:32 -07002356 on enable eager fpu restore
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002357 off disable eager fpu restore
Suresh Siddhae0022982012-09-10 10:32:32 -07002358 auto selects the default scheme, which automatically
2359 enables eagerfpu restore for xsaveopt.
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002360
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01002361 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2362 wfi(ARM) instruction doesn't work correctly and not to
2363 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07002364
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06002365 no_file_caps Tells the kernel not to honor file capabilities. The
2366 only way then for a file to be executed with privilege
2367 is to be setuid root or executed by root.
2368
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369 nohalt [IA-64] Tells the kernel not to use the power saving
2370 function PAL_HALT_LIGHT when idle. This increases
2371 power-consumption. On the positive side, it reduces
2372 interrupt wake-up latency, which may improve performance
2373 in certain environments such as networked servers or
2374 real-time systems.
2375
Kees Cooka6e15a32014-06-13 13:30:35 -07002376 nohibernate [HIBERNATION] Disable hibernation and resume.
2377
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08002378 nohz= [KNL] Boottime enable/disable dynamic ticks
2379 Valid arguments: on, off
2380 Default: on
2381
Frederic Weisbeckerc5bfece2013-04-12 16:45:34 +02002382 nohz_full= [KNL,BOOT]
2383 In kernels built with CONFIG_NO_HZ_FULL=y, set
Frederic Weisbeckera8318812012-12-18 17:32:19 +01002384 the specified list of CPUs whose tick will be stopped
Frederic Weisbecker0453b432013-03-27 02:18:34 +01002385 whenever possible. The boot CPU will be forced outside
2386 the range to maintain the timekeeping.
Frederic Weisbeckerd1e43fa2013-03-26 23:47:24 +01002387 The CPUs in this range must also be included in the
2388 rcu_nocbs= set.
Frederic Weisbeckera8318812012-12-18 17:32:19 +01002389
Paul Mundteeee7852009-04-02 12:31:16 +09002390 noiotrap [SH] Disables trapped I/O port accesses.
2391
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002392 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393 disable unhandled interrupt sources.
2394
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302395 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01002396 broken timer IRQ sources.
2397
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398 noisapnp [ISAPNP] Disables ISA PnP code.
2399
2400 noinitrd [RAM] Tells the kernel not to load any configured
2401 initial RAM disk.
2402
Weidong Han03ea8152009-04-17 16:42:15 +08002403 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
2404 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07002405 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08002406
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407 nointroute [IA-64]
2408
Randy Dunlap16290242011-08-13 12:34:52 -07002409 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07002410
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02002411 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
2412
Gleb Natapovfd10cde2010-10-14 11:22:51 +02002413 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
2414 fault handling.
2415
Glauber Costad910f5c2011-07-11 15:28:19 -04002416 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
2417 steal time is computed, but won't influence scheduler
2418 behaviour
2419
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002420 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002421
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002422 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08002423
Linus Torvalds1da177e2005-04-16 15:20:36 -07002424 noltlbs [PPC] Do not use large page/tlb entries for kernel
2425 lowmem mapping on PPC40x.
2426
Horms312f1f02006-02-22 09:57:55 +09002427 nomca [IA-64] Disable machine check abort handling
2428
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002429 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02002430
Andres Salomon83d73842007-10-12 23:04:06 +02002431 nomfgpt [X86-32] Disable Multi-Function General Purpose
2432 Timer usage (for AMD Geode machines).
2433
Don Zickusbda62632011-10-13 15:14:27 -04002434 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
2435 shutdown the other cpus. Instead use the REBOOT_VECTOR
2436 irq.
2437
Dave Young02608be2012-02-01 10:33:14 +08002438 nomodule Disable module load
2439
Jiri Kosina016ddd92010-01-18 17:05:40 +01002440 nopat [X86] Disable PAT (page attribute table extension of
2441 pagetables) support.
2442
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002443 norandmaps Don't use address space randomization. Equivalent to
2444 echo 0 > /proc/sys/kernel/randomize_va_space
2445
Jiri Kosinabbff2162010-08-11 18:34:09 +02002446 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02002447
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002448 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002449 with UP alternatives
2450
H. Peter Anvin7a5091d2014-05-11 20:25:20 -07002451 nordrand [X86] Disable kernel use of the RDRAND and
2452 RDSEED instructions even if they are supported
2453 by the processor. RDRAND and RDSEED are still
2454 available to user space applications.
H. Peter Anvin49d859d2011-07-31 14:02:19 -07002455
Randy Dunlapa9913042005-10-23 12:57:11 -07002456 noresume [SWSUSP] Disables resume and restores original swap
2457 space.
2458
Linus Torvalds1da177e2005-04-16 15:20:36 -07002459 no-scroll [VGA] Disables scrollback.
2460 This is required for the Braillex ib80-piezo Braille
2461 reader made by F.H. Papenmeier (Germany).
2462
2463 nosbagart [IA-64]
2464
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002465 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08002466
Len Brown61ec7562007-08-16 03:34:22 -04002467 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
2468 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469
Dave Jones97842212007-07-15 23:41:05 -07002470 nosoftlockup [KNL] Disable the soft-lockup detector.
2471
Linus Torvalds1da177e2005-04-16 15:20:36 -07002472 nosync [HW,M68K] Disables sync negotiation for all devices.
2473
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002474 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07002475
2476 nousb [USB] Disable the USB subsystem
2477
Ben Hutchings55142372011-01-02 23:02:42 +00002478 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04002479
Linus Torvalds1da177e2005-04-16 15:20:36 -07002480 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07002481
Weidong Han2b2fd872009-04-17 16:42:12 +08002482 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2483
Fenghua Yuf78cff42012-11-13 11:32:38 -08002484 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2485 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2486 Some features depend on CPU0. Known dependencies are:
2487 1. Resume from suspend/hibernate depends on CPU0.
2488 Suspend/hibernate will fail if CPU0 is offline and you
2489 need to online CPU0 before suspend/hibernate.
2490 2. PIC interrupts also depend on CPU0. CPU0 can't be
2491 removed if a PIC interrupt is detected.
2492 It's said poweroff/reboot may depend on CPU0 on some
2493 machines although I haven't seen such issues so far
2494 after CPU0 is offline on a few tested machines.
2495 If the dependencies are under your control, you can
2496 turn on cpu0_hotplug.
2497
Randy Dunlap16290242011-08-13 12:34:52 -07002498 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07002499 purges which is reported from either PAL_VM_SUMMARY or
2500 SAL PALO.
2501
Yinghai Lu2b633e32010-02-10 01:20:37 -08002502 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2503 could support. nr_cpus=n : n >= 1 limits the kernel to
2504 supporting 'n' processors. Later in runtime you can not
2505 use hotplug cpu feature to put more cpu back to online.
2506 just like you compile the kernel NR_CPUS=n
2507
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002508 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2509
Mel Gorman1a687c22012-11-22 11:16:36 +00002510 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2511 Allowed values are enable and disable
2512
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07002513 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2514 one of ['zone', 'node', 'default'] can be specified
2515 This can be set from sysctl after boot.
2516 See Documentation/sysctl/vm.txt for details.
2517
Randy Dunlap7c4be252009-01-06 14:42:44 -08002518 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2519 See Documentation/debugging-via-ohci1394.txt for more
2520 info.
2521
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07002522 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2523 Rather than timing out after 20 ms if an EC
2524 command is not properly ACKed, override the length
2525 of the timeout. We have interrupts disabled while
2526 waiting for the ACK, so if this is set too high
2527 interrupts *may* be lost!
2528
Tony Lindgren15ac7af2009-12-11 16:16:32 -08002529 omap_mux= [OMAP] Override bootloader pin multiplexing.
2530 Format: <mux_mode0.mode_name=value>...
2531 For example, to override I2C bus2:
2532 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2533
Linus Torvalds1da177e2005-04-16 15:20:36 -07002534 oprofile.timer= [HW]
2535 Use timer interrupt instead of performance counters
2536
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002537 oprofile.cpu_type= Force an oprofile cpu type
2538 This might be useful if you have an older oprofile
2539 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02002540 Format: { arch_perfmon }
2541 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002542 perfmon on Intel CPUs instead of the
2543 CPU specific event set.
Robert Richter159a80b2011-10-11 19:39:16 +02002544 timer: [X86] Force use of architectural NMI
2545 timer mode (see also oprofile.timer
2546 for generic hr timer mode)
Andreas Krebbeldd3c46702011-11-25 20:03:05 +01002547 [s390] Force legacy basic mode sampling
2548 (report cpu_type "timer")
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02002549
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002550 oops=panic Always panic on oopses. Default is to just kill the
2551 process, but there is a small probability of
2552 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07002553 This will also cause panics on machine check exceptions.
2554 Useful together with panic=30 to trigger a reboot.
2555
Randy Dunlapbcfde332010-06-07 17:10:38 -07002556 OSS [HW,OSS]
2557 See Documentation/sound/oss/oss-parameters.txt
2558
Joonsoo Kim48c96a32014-12-12 16:56:01 -08002559 page_owner= [KNL] Boot-time page_owner enabling option.
2560 Storage of the information about who allocated
2561 each page is disabled in default. With this switch,
2562 we can turn it on.
2563 on: enable the feature
2564
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002565 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07002566 timeout > 0: seconds before rebooting
2567 timeout = 0: wait forever
2568 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07002569 Format: <timeout>
2570
Prarit Bhargava9e3961a2014-12-10 15:45:50 -08002571 panic_on_warn panic() instead of WARN(). Useful to cause kdump
2572 on a WARN().
2573
Masami Hiramatsuf06e5152014-06-06 14:37:07 -07002574 crash_kexec_post_notifiers
2575 Run kdump after running panic-notifiers and dumping
2576 kmsg. This only for the users who doubt kdump always
2577 succeeds in any situation.
2578 Note that this also increases risks of kdump failure,
2579 because some panic notifiers can make the crashed
2580 kernel more unstable.
2581
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 parkbd.port= [HW] Parallel port number the keyboard adapter is
2583 connected to, default is 0.
2584 Format: <parport#>
2585 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2586 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07002587 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002588
Randy Dunlapa9913042005-10-23 12:57:11 -07002589 parport= [HW,PPT] Specify parallel ports. 0 disables.
2590 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2591 Use 'auto' to force the driver to use any
2592 IRQ/DMA settings detected (the default is to
2593 ignore detected IRQ/DMA settings because of
2594 possible conflicts). You can specify the base
2595 address, IRQ, and DMA settings; IRQ and DMA
2596 should be numbers, or 'auto' (for using detected
2597 settings on that particular port), or 'nofifo'
2598 (to avoid using a FIFO even if it is detected).
2599 Parallel ports are assigned in the order they
2600 are specified on the command line, starting
2601 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002602
Randy Dunlapa9913042005-10-23 12:57:11 -07002603 parport_init_mode= [HW,PPT]
2604 Configure VIA parallel port to operate in
2605 a specific mode. This is necessary on Pegasos
2606 computer where firmware has no options for setting
2607 up parallel port mode and sets it to spp.
2608 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 Format: [spp|ps2|epp|ecp|ecpepp]
2610
Andrew Mortondd287792006-03-23 03:00:57 -08002611 pause_on_oops=
2612 Halt all CPUs after the first oops has been printed for
2613 the specified number of seconds. This is to be used if
2614 your oopses keep scrolling off the screen.
2615
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 pcbit= [HW,ISDN]
2617
2618 pcd. [PARIDE]
2619 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002620 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621
Randy Dunlapa9913042005-10-23 12:57:11 -07002622 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07002623 earlydump [X86] dump PCI config space before the kernel
2624 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02002625 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002626 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07002627 the hardware directly. Use this if your machine
2628 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002629 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07002630 hardware access methods are allowed. Use this
2631 if you experience crashes upon bootup and you
2632 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002633 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002634 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02002635 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002636 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07002637 noaer [PCIE] If the PCIEAER kernel config parameter is
2638 enabled, this kernel boot option can be used to
2639 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04002640 nodomains [PCI] Disable support for multiple PCI
2641 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302642 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08002643 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02002644 check_enable_amd_mmconf [X86] check for and enable
2645 properly configured MMIO access to PCI
2646 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07002647 nomsi [MSI] If the PCI_MSI kernel config parameter is
2648 enabled, this kernel boot option can be used to
2649 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02002650 noioapicquirk [APIC] Disable all boot interrupt quirks.
2651 Safety option to keep boot IRQs enabled. This
2652 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02002653 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2654 primary IO-APIC for bridges that cannot disable
2655 boot IRQs. This fixes a source of spurious IRQs
2656 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02002657 noioapicreroute [APIC] Disable workaround that uses the
2658 boot IRQ equivalent of an IRQ that connects to
2659 a chipset where boot IRQs cannot be disabled.
2660 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002661 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07002662 routing table. These calls are known to be buggy
2663 on several machines and they hang the machine
2664 when used, but on other computers it's the only
2665 way to get the interrupt routing table. Try
2666 this option if the kernel is unable to allocate
2667 IRQs or discover secondary PCI buses on your
2668 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02002669 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07002670 Use with caution as certain devices share
2671 address decoders between ROMs and other
2672 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02002673 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07002674 expansion ROMs that do not already have
2675 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07002676 nobar [X86] Do not assign address space to the
2677 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002678 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002679 assigned automatically to PCI devices. You can
2680 make the kernel exclude IRQs of your ISA cards
2681 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002682 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002683 of the PIRQ table (normally generated
2684 by the BIOS) if it is outside the
2685 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002686 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002687 useful if the kernel is unable to find your
2688 secondary buses and you want to tell it
2689 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002690 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002691 numbers ourselves, overriding
2692 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002693 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002694 in the BIOS $PIR table. This is needed on
2695 some systems with broken BIOSes, notably
2696 some HP Pavilion N5400 and Omnibook XE3
2697 notebooks. This will have no effect if ACPI
2698 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002699 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002700 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002701 use_crs [X86] Use PCI host bridge window information
2702 from ACPI. On BIOSes from 2008 or later, this
2703 is enabled by default. If you need to use this,
2704 please report a bug.
2705 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2706 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002707 routeirq Do IRQ routing for all PCI devices.
2708 This is normally done in pci_enable_device(),
2709 so this option is a temporary workaround
2710 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002711 skip_isa_align [X86] do not align io start addr, so can
2712 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002713 firmware [ARM] Do not re-enumerate the bus but instead
2714 just use the configuration from the
2715 bootloader. This is currently used on
2716 IXP2000 systems where the bus has to be
2717 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002718 noearly [X86] Don't do any early type 1 scanning.
2719 This might help on some broken boards which
2720 machine check when some devices' config space
2721 is read. But various workarounds are disabled
2722 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002723 bfsort Sort PCI devices into breadth-first order.
2724 This sorting is done to get a device
2725 order compatible with older (<= 2.4) kernels.
2726 nobfsort Don't sort PCI devices into breadth-first order.
Yijing Wangfa238712013-01-30 09:40:52 +08002727 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2728 tuning and use the BIOS-configured MPS defaults.
2729 pcie_bus_safe Set every device's MPS to the largest value
2730 supported by all devices below the root complex.
2731 pcie_bus_perf Set device MPS to the largest allowable MPS
2732 based on its parent bus. Also set MRRS (Max
2733 Read Request Size) to the largest supported
2734 value (no larger than the MPS that the device
2735 or bus can support) for best performance.
2736 pcie_bus_peer2peer Set every device's MPS to 128B, which
2737 every device is guaranteed to support. This
2738 configuration allows peer-to-peer DMA between
2739 any pair of devices, possibly at the cost of
2740 reduced performance. This also guarantees
2741 that hot-added devices will work.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002742 cbiosize=nn[KMG] The fixed amount of bus space which is
2743 reserved for the CardBus bridge's IO window.
2744 The default value is 256 bytes.
2745 cbmemsize=nn[KMG] The fixed amount of bus space which is
2746 reserved for the CardBus bridge's memory
2747 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002748 resource_alignment=
2749 Format:
2750 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2751 Specifies alignment and device to reassign
2752 aligned memory resources.
2753 If <order of align> is not specified,
2754 PAGE_SIZE is used as alignment.
2755 PCI-PCI bridge can be specified, if resource
2756 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002757 ecrc= Enable/disable PCIe ECRC (transaction layer
2758 end-to-end CRC checking).
2759 bios: Use BIOS/firmware settings. This is the
2760 the default.
2761 off: Turn ECRC off
2762 on: Turn ECRC on.
Yijing Wang8c8803c2013-01-23 20:29:06 +08002763 hpiosize=nn[KMG] The fixed amount of bus space which is
2764 reserved for hotplug bridge's IO window.
2765 Default size is 256 bytes.
2766 hpmemsize=nn[KMG] The fixed amount of bus space which is
2767 reserved for hotplug bridge's memory window.
2768 Default size is 2 megabytes.
Yinghai Lub55438f2012-02-23 19:23:30 -08002769 realloc= Enable/disable reallocating PCI bridge resources
2770 if allocations done by BIOS are too small to
2771 accommodate resources required by all child
2772 devices.
2773 off: Turn realloc off
2774 on: Turn realloc on
2775 realloc same as realloc=on
Rafael J. Wysocki6748dcc2012-03-01 00:06:33 +01002776 noari do not use PCIe ARI.
Bjorn Helgaas284f5f92012-04-30 15:21:02 -06002777 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2778 only look for one device below a PCIe downstream
2779 port.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002780
Chuck Ebberte5665a42008-09-24 20:40:34 -04002781 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2782 Management.
2783 off Disable ASPM.
2784 force Enable ASPM even on devices that claim not to support it.
2785 WARNING: Forcing ASPM on may cause system lockups.
2786
MUNEDA Takahiro7570a332012-02-02 11:09:22 -05002787 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2788 nomsi Do not use MSI for PCI Express Native Hotplug (this
2789 makes all PCIe ports use INTx for hotplug services).
2790
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002791 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002792 auto Ask the BIOS whether or not to use native PCIe services
2793 associated with PCIe ports (PME, hot-plug, AER). Use
2794 them only if that is allowed by the BIOS.
2795 native Use native PCIe services associated with PCIe ports
2796 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002797 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2798 ports driver.
2799
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002800 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002801 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002802 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002803
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804 pcmv= [HW,PCMCIA] BadgePAD 4
2805
Tushar Behera39ac5ba2014-03-28 10:50:21 +05302806 pd_ignore_unused
2807 [PM]
2808 Keep all power-domains already enabled by bootloader on,
2809 even if no driver has claimed them. This is useful
2810 for debug and development, but should not be
2811 needed on a platform with proper driver support.
2812
Linus Torvalds1da177e2005-04-16 15:20:36 -07002813 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002814 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815
2816 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2817 boot time.
2818 Format: { 0 | 1 }
2819 See arch/parisc/kernel/pdc_chassis.c
2820
Tejun Heof58dc012009-08-14 15:00:50 +09002821 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002822 Currently supported values are "embed" and "page".
2823 Archs may support subset or none of the selections.
2824 See comments in mm/percpu.c for details on each
2825 allocator. This parameter is primarily for debugging
2826 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002827
Linus Torvalds1da177e2005-04-16 15:20:36 -07002828 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002829 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002830
2831 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002832 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002833
2834 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002835 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836
2837 plip= [PPT,NET] Parallel port network link
2838 Format: { parport<nr> | timid | 0 }
2839 See also Documentation/parport.txt.
2840
Randy Dunlap16290242011-08-13 12:34:52 -07002841 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002842 Override pmtimer IOPort with a hex value.
2843 e.g. pmtmr=0x508
2844
Bjorn Helgaas96242112011-08-11 12:14:05 -06002845 pnp.debug=1 [PNP]
2846 Enable PNP debug messages (depends on the
2847 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2848 via /sys/module/pnp/parameters/debug. We always show
2849 current resource usage; turning this on also shows
2850 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002851
Linus Torvalds1da177e2005-04-16 15:20:36 -07002852 pnpacpi= [ACPI]
2853 { off }
2854
2855 pnpbios= [ISAPNP]
2856 { on | off | curr | res | no-curr | no-res }
2857
2858 pnp_reserve_irq=
2859 [ISAPNP] Exclude IRQs for the autoconfiguration
2860
2861 pnp_reserve_dma=
2862 [ISAPNP] Exclude DMAs for the autoconfiguration
2863
2864 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002865 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002866
2867 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002868 [ISAPNP] Exclude memory regions for the
2869 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002870 Ranges are in pairs (memory base and size).
2871
Randy Dunlap4af94f32009-04-17 18:30:28 -07002872 ports= [IP_VS_FTP] IPVS ftp helper module
2873 Default is 21.
2874 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2875 may be specified.
2876 Format: <port>,<port>....
2877
Ingo Molnar45807a12007-07-15 23:40:10 -07002878 print-fatal-signals=
2879 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002880
2881 If enabled, warn about various signal handling
2882 related application anomalies: too many signals,
2883 too many POSIX.1 timers, fatal signals causing a
2884 coredump - etc.
2885
2886 If you hit the warning due to signal overflow,
2887 you might want to try "ulimit -i unlimited".
2888
Ingo Molnar45807a12007-07-15 23:40:10 -07002889 default: off.
2890
Matthew Garrettc22ab3322012-03-05 14:59:10 -08002891 printk.always_kmsg_dump=
2892 Trigger kmsg_dump for cases other than kernel oops or
2893 panics
2894 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2895 default: disabled
2896
Randy Dunlape84845c2007-07-15 23:40:25 -07002897 printk.time= Show timing data prefixed to each printk message line
2898 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2899
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002900 processor.max_cstate= [HW,ACPI]
2901 Limit processor to maximum C-state
2902 max_cstate=9 overrides any DMI blacklist limit.
2903
2904 processor.nocst [HW,ACPI]
2905 Ignore the _CST method to determine C-states,
2906 instead using the legacy FADT method
2907
Linus Torvalds1da177e2005-04-16 15:20:36 -07002908 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002909 Format: [schedule,]<number>
2910 Param: "schedule" - profile schedule points.
2911 Param: <number> - step/bucket size as a power of 2 for
2912 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002913 Param: "sleep" - profile D-state sleeping (millisecs).
2914 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002915 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002916
Linus Torvalds1da177e2005-04-16 15:20:36 -07002917 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2918 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002919 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920
Randy Dunlapa9913042005-10-23 12:57:11 -07002921 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2922 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002923 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2924 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002925 psmouse.resetafter= [HW,MOUSE]
2926 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002927 (0 = never).
2928 psmouse.resolution=
2929 [HW,MOUSE] Set desired mouse resolution, in dpi.
2930 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002931 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002932 0 = disabled, 1 = enabled (default).
2933
Matthew Garrettdee28e72011-07-21 16:57:55 -04002934 pstore.backend= Specify the name of the pstore backend to use
2935
Linus Torvalds1da177e2005-04-16 15:20:36 -07002936 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002937 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938
Kay Sieversdc8c8582007-08-15 12:25:38 +02002939 pty.legacy_count=
2940 [KNL] Number of legacy pty's. Overwrites compiled-in
2941 default number.
2942
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002943 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002944
Linus Torvalds1da177e2005-04-16 15:20:36 -07002945 r128= [HW,DRM]
2946
2947 raid= [HW,RAID]
2948 See Documentation/md.txt.
2949
Randy Dunlapa9913042005-10-23 12:57:11 -07002950 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002951 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002952
Linus Torvalds1da177e2005-04-16 15:20:36 -07002953 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002954 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002956 rcu_nocbs= [KNL]
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002957 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2958 the specified list of CPUs to be no-callback CPUs.
2959 Invocation of these CPUs' RCU callbacks will
Paul E. McKenneya4889852012-12-03 08:16:28 -08002960 be offloaded to "rcuox/N" kthreads created for
2961 that purpose, where "x" is "b" for RCU-bh, "p"
2962 for RCU-preempt, and "s" for RCU-sched, and "N"
2963 is the CPU number. This reduces OS jitter on the
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002964 offloaded CPUs, which can be useful for HPC and
2965 real-time workloads. It can also improve energy
2966 efficiency for asymmetric multiprocessors.
2967
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002968 rcu_nocb_poll [KNL]
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002969 Rather than requiring that offloaded CPUs
2970 (specified by rcu_nocbs= above) explicitly
2971 awaken the corresponding "rcuoN" kthreads,
2972 make these kthreads poll for callbacks.
2973 This improves the real-time response for the
2974 offloaded CPUs by relieving them of the need to
2975 wake up the corresponding kthread, but degrades
2976 energy efficiency by requiring that the kthreads
2977 periodically wake up to do the polling.
2978
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002979 rcutree.blimit= [KNL]
Paul E. McKenney97e63f02013-10-27 09:44:03 -07002980 Set maximum number of finished RCU callbacks to
2981 process in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002982
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002983 rcutree.rcu_fanout_leaf= [KNL]
Paul E. McKenneyf885b7f2012-04-23 15:52:53 -07002984 Increase the number of CPUs assigned to each
2985 leaf rcu_node structure. Useful for very large
2986 systems.
2987
Paul E. McKenney4a81e832014-06-20 16:49:01 -07002988 rcutree.jiffies_till_sched_qs= [KNL]
2989 Set required age in jiffies for a
2990 given grace period before RCU starts
2991 soliciting quiescent-state help from
2992 rcu_note_context_switch().
2993
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002994 rcutree.jiffies_till_first_fqs= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08002995 Set delay from grace-period initialization to
2996 first attempt to force quiescent states.
2997 Units are jiffies, minimum value is zero,
2998 and maximum value is HZ.
2999
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003000 rcutree.jiffies_till_next_fqs= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003001 Set delay between subsequent attempts to force
3002 quiescent states. Units are jiffies, minimum
3003 value is one, and maximum value is HZ.
3004
Clark Williams21871d72014-09-12 21:21:09 -05003005 rcutree.kthread_prio= [KNL,BOOT]
3006 Set the SCHED_FIFO priority of the RCU
3007 per-CPU kthreads (rcuc/N). This value is also
3008 used for the priority of the RCU boost threads
3009 (rcub/N). Valid values are 1-99 and the default
3010 is 1 (the least-favored priority).
3011
Paul E. McKenneyfbce7492014-06-24 09:26:11 -07003012 rcutree.rcu_nocb_leader_stride= [KNL]
3013 Set the number of NOCB kthread groups, which
3014 defaults to the square root of the number of
3015 CPUs. Larger numbers reduces the wakeup overhead
3016 on the per-CPU grace-period kthreads, but increases
3017 that same overhead on each group's leader.
3018
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003019 rcutree.qhimark= [KNL]
Paul E. McKenney97e63f02013-10-27 09:44:03 -07003020 Set threshold of queued RCU callbacks beyond which
3021 batch limiting is disabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08003022
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003023 rcutree.qlowmark= [KNL]
Robert P. J. Day24aaef82008-02-03 15:20:26 +02003024 Set threshold of queued RCU callbacks below which
3025 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08003026
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003027 rcutree.rcu_idle_gp_delay= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003028 Set wakeup interval for idle CPUs that have
3029 RCU callbacks (RCU_FAST_NO_HZ=y).
Paul E. McKenneyd40011f2012-06-26 20:45:57 -07003030
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003031 rcutree.rcu_idle_lazy_gp_delay= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003032 Set wakeup interval for idle CPUs that have
3033 only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
3034 Lazy RCU callbacks are those which RCU can
3035 prove do nothing more than free memory.
Paul E. McKenneyd40011f2012-06-26 20:45:57 -07003036
Paul E. McKenney38706bc2014-08-18 21:12:17 -07003037 rcutorture.cbflood_inter_holdoff= [KNL]
3038 Set holdoff time (jiffies) between successive
3039 callback-flood tests.
3040
3041 rcutorture.cbflood_intra_holdoff= [KNL]
3042 Set holdoff time (jiffies) between successive
3043 bursts of callbacks within a given callback-flood
3044 test.
3045
3046 rcutorture.cbflood_n_burst= [KNL]
3047 Set the number of bursts making up a given
3048 callback-flood test. Set this to zero to
3049 disable callback-flood testing.
3050
3051 rcutorture.cbflood_n_per_burst= [KNL]
3052 Set the number of callbacks to be registered
3053 in a given burst of a callback-flood test.
3054
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003055 rcutorture.fqs_duration= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003056 Set duration of force_quiescent_state bursts.
3057
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003058 rcutorture.fqs_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003059 Set holdoff time within force_quiescent_state bursts.
3060
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003061 rcutorture.fqs_stutter= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003062 Set wait time between force_quiescent_state bursts.
3063
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003064 rcutorture.gp_exp= [KNL]
3065 Use expedited update-side primitives.
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003066
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003067 rcutorture.gp_normal= [KNL]
3068 Use normal (non-expedited) update-side primitives.
3069 If both gp_exp and gp_normal are set, do both.
3070 If neither gp_exp nor gp_normal are set, still
3071 do both.
3072
3073 rcutorture.n_barrier_cbs= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003074 Set callbacks/threads for rcu_barrier() testing.
3075
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003076 rcutorture.nfakewriters= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003077 Set number of concurrent RCU writers. These just
3078 stress RCU, they don't participate in the actual
3079 test, hence the "fake".
3080
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003081 rcutorture.nreaders= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003082 Set number of RCU readers.
3083
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003084 rcutorture.object_debug= [KNL]
3085 Enable debug-object double-call_rcu() testing.
3086
3087 rcutorture.onoff_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003088 Set time (s) after boot for CPU-hotplug testing.
3089
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003090 rcutorture.onoff_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003091 Set time (s) between CPU-hotplug operations, or
3092 zero to disable CPU-hotplug testing.
3093
Paul E. McKenney59da22a2014-09-12 10:36:15 -07003094 rcutorture.torture_runnable= [BOOT]
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003095 Start rcutorture running at boot time.
3096
3097 rcutorture.shuffle_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003098 Set task-shuffle interval (s). Shuffling tasks
3099 allows some CPUs to go into dyntick-idle mode
3100 during the rcutorture test.
3101
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003102 rcutorture.shutdown_secs= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003103 Set time (s) after boot system shutdown. This
3104 is useful for hands-off automated testing.
3105
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003106 rcutorture.stall_cpu= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003107 Duration of CPU stall (s) to test RCU CPU stall
3108 warnings, zero to disable.
3109
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003110 rcutorture.stall_cpu_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003111 Time to wait (s) after boot before inducing stall.
3112
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003113 rcutorture.stat_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003114 Time (s) between statistics printk()s.
3115
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003116 rcutorture.stutter= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003117 Time (s) to stutter testing, for example, specifying
3118 five seconds causes the test to run for five seconds,
3119 wait for five seconds, and so on. This tests RCU's
3120 ability to transition abruptly to and from idle.
3121
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003122 rcutorture.test_boost= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003123 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
3124 "Maybe" means test if the RCU implementation
3125 under test support RCU priority boosting.
3126
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003127 rcutorture.test_boost_duration= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003128 Duration (s) of each individual boost test.
3129
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003130 rcutorture.test_boost_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003131 Interval (s) between each boost test.
3132
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003133 rcutorture.test_no_idle_hz= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003134 Test RCU's dyntick-idle handling. See also the
3135 rcutorture.shuffle_interval parameter.
3136
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003137 rcutorture.torture_type= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003138 Specify the RCU implementation to test.
3139
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003140 rcutorture.verbose= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003141 Enable additional printk() statements.
3142
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003143 rcupdate.rcu_expedited= [KNL]
3144 Use expedited grace-period primitives, for
3145 example, synchronize_rcu_expedited() instead
3146 of synchronize_rcu(). This reduces latency,
3147 but can increase CPU utilization, degrade
3148 real-time latency, and degrade energy efficiency.
3149
3150 rcupdate.rcu_cpu_stall_suppress= [KNL]
3151 Suppress RCU CPU stall warning messages.
3152
3153 rcupdate.rcu_cpu_stall_timeout= [KNL]
3154 Set timeout for RCU CPU stall warning messages.
3155
Paul E. McKenney52db30a2014-07-01 18:16:30 -07003156 rcupdate.rcu_task_stall_timeout= [KNL]
3157 Set timeout in jiffies for RCU task stall warning
3158 messages. Disable with a value less than or equal
3159 to zero.
3160
Pranith Kumar74860fe2014-09-19 11:34:09 -04003161 rcupdate.rcu_self_test= [KNL]
3162 Run the RCU early boot self tests
3163
3164 rcupdate.rcu_self_test_bh= [KNL]
3165 Run the RCU bh early boot self tests
3166
3167 rcupdate.rcu_self_test_sched= [KNL]
3168 Run the RCU sched early boot self tests
3169
Olof Johanssonffdfc402005-09-06 15:17:19 -07003170 rdinit= [KNL]
3171 Format: <full_path>
3172 Run specified binary instead of /init from the ramdisk,
3173 used for early userspace startup. See initrd.
3174
Robin Holt1b3a5d02013-07-08 16:01:42 -07003175 reboot= [KNL]
3176 Format (x86 or x86_64):
3177 [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
3178 [[,]s[mp]#### \
3179 [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
3180 [[,]f[orce]
3181 Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
3182 reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
3183 reboot_force is either force or not specified,
3184 reboot_cpu is s[mp]#### with #### being the processor
3185 to be used for rebooting.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003186
Paul Jackson46b6d942008-07-04 10:00:09 -07003187 relax_domain_level=
3188 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01003189 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07003190
Rafael J. Wysocki0399d4d2014-05-26 13:40:59 +02003191 relative_sleep_states=
3192 [SUSPEND] Use sleep state labeling where the deepest
3193 state available other than hibernation is always "mem".
3194 Format: { "0" | "1" }
3195 0 -- Traditional sleep state labels.
3196 1 -- Relative sleep state labels.
3197
Linus Torvalds1da177e2005-04-16 15:20:36 -07003198 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
3199
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003200 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07003201 Format: nn[KMG]
3202 Reserves a hole at the top of the kernel virtual
3203 address space.
3204
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07003205 reservelow= [X86]
3206 Format: nn[K]
3207 Set the amount of memory to reserve for BIOS at
3208 the bottom of the address space.
3209
Vivek Goyal7e962872006-09-27 01:50:44 -07003210 reset_devices [KNL] Force drivers to reset the underlying device
3211 during initialization.
3212
Randy Dunlapa9913042005-10-23 12:57:11 -07003213 resume= [SWSUSP]
3214 Specify the partition device for software suspend
Minho Ban2df83fa2012-05-14 21:45:31 +02003215 Format:
3216 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003217
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08003218 resume_offset= [SWSUSP]
3219 Specify the offset from the beginning of the partition
3220 given by "resume=" at which the swap header is located,
3221 in <PAGE_SIZE> units (needed only for swap files).
3222 See Documentation/power/swsusp-and-swap-files.txt
3223
Barry Songf126f732011-10-10 23:38:41 +02003224 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
3225 read the resume files
3226
Barry Song6f8d7022011-10-06 20:34:46 +02003227 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
3228 Useful for devices that are detected asynchronously
3229 (e.g. USB and MMC devices).
3230
Bojan Smojverf996fc92010-09-09 23:06:23 +02003231 hibernate= [HIBERNATION]
3232 noresume Don't check if there's a hibernation image
3233 present during boot.
3234 nocompress Don't compress/decompress hibernation images.
Kees Cooka6e15a32014-06-13 13:30:35 -07003235 no Disable hibernation and resume.
Bojan Smojverf996fc92010-09-09 23:06:23 +02003236
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08003237 retain_initrd [RAM] Keep initrd memory after extraction
3238
Andrew Clausen0efbb782015-01-09 20:24:55 +00003239 rfkill.default_state=
3240 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm,
3241 etc. communication is blocked by default.
3242 1 Unblocked.
3243
3244 rfkill.master_switch_mode=
3245 0 The "airplane mode" button does nothing.
3246 1 The "airplane mode" button toggles between everything
3247 blocked and the previous configuration.
3248 2 The "airplane mode" button toggles between everything
3249 blocked and everything unblocked.
3250
Linus Torvalds1da177e2005-04-16 15:20:36 -07003251 rhash_entries= [KNL,NET]
3252 Set number of hash buckets for route cache
3253
Linus Torvalds1da177e2005-04-16 15:20:36 -07003254 ro [KNL] Mount root device read-only on boot
3255
3256 root= [KNL] Root filesystem
Will Drewryf2d34fd92011-08-03 16:21:08 -07003257 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003258
3259 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
3260 mount the root filesystem
3261
3262 rootflags= [KNL] Set root filesystem mount option string
3263
3264 rootfstype= [KNL] Set root filesystem type
3265
Pierre Ossmancc1ed752007-07-15 23:40:35 -07003266 rootwait [KNL] Wait (indefinitely) for root device to show up.
3267 Useful for devices that are detected asynchronously
3268 (e.g. USB and MMC devices).
3269
Robert Tivy5c71d612013-03-28 18:41:46 -07003270 rproc_mem=nn[KMG][@address]
3271 [KNL,ARM,CMA] Remoteproc physical memory block.
3272 Memory area to be used by remote processor image,
3273 managed by CMA.
3274
Linus Torvalds1da177e2005-04-16 15:20:36 -07003275 rw [KNL] Mount root device read-write on boot
3276
3277 S [KNL] Run init in single mode
3278
Gerald Schaeferc60d1ae2014-07-18 17:37:08 +02003279 s390_iommu= [HW,S390]
3280 Set s390 IOTLB flushing mode
3281 strict
3282 With strict flushing every unmap operation will result in
3283 an IOTLB flush. Default is lazy flushing before reuse,
3284 which is faster.
3285
Linus Torvalds1da177e2005-04-16 15:20:36 -07003286 sa1100ir [NET]
3287 See drivers/net/irda/sa1100_ir.c.
3288
Linus Torvalds1da177e2005-04-16 15:20:36 -07003289 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07003290
Mike Travisf6630112009-11-17 18:22:15 -06003291 sched_debug [KNL] Enables verbose scheduler debug messages.
3292
Mike Galbraith5307c952012-05-08 12:20:58 +02003293 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
3294 xtime_lock contention on larger systems, and/or RCU lock
3295 contention on all systems with CONFIG_MAXSMP set.
3296 Format: { "0" | "1" }
3297 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
3298 1 -- enable.
3299 Note: increases power consumption, thus should only be
3300 enabled if running jitter sensitive (HPC/RT) workloads.
3301
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003302 security= [SECURITY] Choose a security module to enable at boot.
3303 If this boot parameter is not specified, only the first
3304 security module asking for security registration will be
3305 loaded. An invalid security module name will be treated
3306 as if no module has been chosen.
3307
3308 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003309 Format: { "0" | "1" }
3310 See security/selinux/Kconfig help text.
3311 0 -- disable.
3312 1 -- enable.
3313 Default value is set via kernel config option.
3314 If enabled at boot time, /selinux/disable can be used
3315 later to disable prior to initial policy load.
3316
John Johansenc1c124e2010-07-29 14:48:09 -07003317 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
3318 Format: { "0" | "1" }
3319 See security/apparmor/Kconfig help text
3320 0 -- disable.
3321 1 -- enable.
3322 Default value is set via kernel config option.
3323
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003324 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07003325
Linus Torvalds1da177e2005-04-16 15:20:36 -07003326 shapers= [NET]
3327 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07003328
Yinghai Lub05f78f2008-08-22 01:32:50 -07003329 show_msr= [x86] show boot-time MSR settings
3330 Format: { <integer> }
3331 Show boot-time (BIOS-initialized) MSR settings.
3332 The parameter means the number of CPUs to show,
3333 for example 1 means boot CPU only.
3334
Linus Torvalds1da177e2005-04-16 15:20:36 -07003335 simeth= [IA-64]
3336 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07003337
Linus Torvalds1da177e2005-04-16 15:20:36 -07003338 slram= [HW,MTD]
3339
Joonsoo Kim423c9292014-10-09 15:26:22 -07003340 slab_nomerge [MM]
3341 Disable merging of slabs with similar size. May be
3342 necessary if there is some reason to distinguish
3343 allocs to different slabs. Debug options disable
3344 merging on their own.
3345 For more information see Documentation/vm/slub.txt.
3346
David Rientjes3df1ccc2011-10-18 22:09:28 -07003347 slab_max_order= [MM, SLAB]
3348 Determines the maximum allowed order for slabs.
3349 A high setting may cause OOMs due to memory
3350 fragmentation. Defaults to 1 for systems with
3351 more than 32MB of RAM, 0 otherwise.
3352
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003353 slub_debug[=options[,slabs]] [MM, SLUB]
3354 Enabling slub_debug allows one to determine the
3355 culprit if slab objects become corrupted. Enabling
3356 slub_debug can create guard zones around objects and
3357 may poison objects when not in use. Also tracks the
3358 last alloc / free. For more information see
3359 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003360
3361 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003362 Determines the maximum allowed order for slabs.
3363 A high setting may cause OOMs due to memory
3364 fragmentation. For more information see
3365 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003366
3367 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003368 The minimum number of objects per slab. SLUB will
3369 increase the slab order up to slub_max_order to
3370 generate a sufficiently large slab able to contain
3371 the number of objects indicated. The higher the number
3372 of objects the smaller the overhead of tracking slabs
3373 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003374 For more information see Documentation/vm/slub.txt.
3375
3376 slub_min_order= [MM, SLUB]
Masanari Iida24775d62012-02-15 00:26:42 +09003377 Determines the minimum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003378 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003379 For more information see Documentation/vm/slub.txt.
3380
3381 slub_nomerge [MM, SLUB]
Joonsoo Kim423c9292014-10-09 15:26:22 -07003382 Same with slab_nomerge. This is supported for legacy.
3383 See slab_nomerge for more information.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003384
Linus Torvalds1da177e2005-04-16 15:20:36 -07003385 smart2= [HW]
3386 Format: <io1>[,<io2>[,...,<io8>]]
3387
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07003388 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
3389 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
3390 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
3391 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
3392 smsc-ircc2.ircc_irq= [HW] IRQ line
3393 smsc-ircc2.ircc_dma= [HW] DMA channel
3394 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3395 0: Toshiba Satellite 1800 (GP data pin select)
3396 1: Fast pin select (default)
3397 2: ATC IRMode
3398
Ingo Molnar9c44bc02008-05-12 21:21:04 +02003399 softlockup_panic=
3400 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07003401 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02003402
Aaron Tomlined235872014-06-23 13:22:05 -07003403 softlockup_all_cpu_backtrace=
3404 [KNL] Should the soft-lockup detector generate
3405 backtraces on all cpus.
3406 Format: <integer>
3407
Linus Torvalds1da177e2005-04-16 15:20:36 -07003408 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02003409 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07003410
Linus Torvalds1da177e2005-04-16 15:20:36 -07003411 spia_io_base= [HW,MTD]
3412 spia_fio_base=
3413 spia_pedr=
3414 spia_peddr=
3415
Steven Rostedtf38f1d22008-12-16 23:06:40 -05003416 stacktrace [FTRACE]
3417 Enabled the stack tracer on boot up.
3418
Steven Rostedt762e1202011-12-19 22:01:00 -05003419 stacktrace_filter=[function-list]
3420 [FTRACE] Limit the functions that the stack tracer
3421 will trace at boot up. function-list is a comma separated
3422 list of functions. This list can be changed at run
3423 time by the stack_trace_filter file in the debugfs
3424 tracing directory. Note, this enables stack tracing
3425 and the stacktrace above is not needed.
3426
Linus Torvalds1da177e2005-04-16 15:20:36 -07003427 sti= [PARISC,HW]
3428 Format: <num>
3429 Set the STI (builtin display/keyboard on the HP-PARISC
3430 machines) console (graphic card) which should be used
3431 as the initial boot-console.
3432 See also comment in drivers/video/console/sticore.c.
3433
3434 sti_font= [HW]
3435 See comment in drivers/video/console/sticore.c.
3436
3437 stifb= [HW]
3438 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3439
Trond Myklebustcbf11072009-08-09 15:06:19 -04003440 sunrpc.min_resvport=
3441 sunrpc.max_resvport=
3442 [NFS,SUNRPC]
3443 SunRPC servers often require that client requests
3444 originate from a privileged port (i.e. a port in the
3445 range 0 < portnr < 1024).
3446 An administrator who wishes to reserve some of these
3447 ports for other uses may adjust the range that the
3448 kernel's sunrpc client considers to be privileged
3449 using these two parameters to set the minimum and
3450 maximum port values.
3451
Greg Banks42a7fc42007-03-06 01:42:23 -08003452 sunrpc.pool_mode=
3453 [NFS]
3454 Control how the NFS server code allocates CPUs to
3455 service thread pools. Depending on how many NICs
3456 you have and where their interrupts are bound, this
3457 option will affect which CPUs will do NFS serving.
3458 Note: this parameter cannot be changed while the
3459 NFS server is running.
3460
3461 auto the server chooses an appropriate mode
3462 automatically using heuristics
3463 global a single global pool contains all CPUs
3464 percpu one pool for each CPU
3465 pernode one pool for each NUMA node (equivalent
3466 to global on non-NUMA machines)
3467
Trond Myklebustcbf11072009-08-09 15:06:19 -04003468 sunrpc.tcp_slot_table_entries=
3469 sunrpc.udp_slot_table_entries=
3470 [NFS,SUNRPC]
3471 Sets the upper limit on the number of simultaneous
3472 RPC calls that can be sent from the client to a
3473 server. Increasing these values may allow you to
3474 improve throughput, but will also increase the
3475 amount of memory reserved for use by the client.
3476
Michal Hocko07555ac2013-08-22 16:35:46 -07003477 swapaccount=[0|1]
Michal Hockoa42c3902010-11-24 12:57:08 -08003478 [KNL] Enable accounting of swap in memory resource
3479 controller if no parameter or 1 is given or disable
3480 it if 0 is given (See Documentation/cgroups/memory.txt)
3481
Jiri Kosina91fec0f2013-11-27 13:48:09 +01003482 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
3483 Format: { <int> | force }
3484 <int> -- Number of I/O TLB slabs
3485 force -- force using of bounce buffers even if they
3486 wouldn't be automatically used by the kernel
Randy Dunlapa9913042005-10-23 12:57:11 -07003487
Linus Torvalds1da177e2005-04-16 15:20:36 -07003488 switches= [HW,M68k]
3489
Andi Kleene52eec12010-09-08 16:54:17 +02003490 sysfs.deprecated=0|1 [KNL]
3491 Enable/disable old style sysfs layout for old udev
3492 on older distributions. When this option is enabled
3493 very new udev will not work anymore. When this option
3494 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3495 in older udev will not work anymore.
3496 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3497 the kernel configuration.
3498
Ingo Molnar5d6f6472006-12-13 00:34:36 -08003499 sysrq_always_enabled
3500 [KNL]
3501 Ignore sysrq setting - this boot parameter will
3502 neutralize any effect of /proc/sys/kernel/sysrq.
3503 Useful for debugging.
3504
Fabian Frederick747029a2014-11-06 19:46:50 +01003505 tcpmhash_entries= [KNL,NET]
3506 Set the number of tcp_metrics_hash slots.
3507 Default value is 8192 or 16384 depending on total
3508 ram pages. This is used to specify the TCP metrics
3509 cache size. See Documentation/networking/ip-sysctl.txt
3510 "tcp_no_metrics_save" section for more details.
3511
Linus Torvalds1da177e2005-04-16 15:20:36 -07003512 tdfx= [HW,DRM]
3513
Srinivas Pandruvadaacc82342014-09-02 11:54:41 -07003514 test_suspend= [SUSPEND][,N]
David Brownell77437fd2008-07-23 21:28:33 -07003515 Specify "mem" (for Suspend-to-RAM) or "standby" (for
Srinivas Pandruvadaacc82342014-09-02 11:54:41 -07003516 standby suspend) or "freeze" (for suspend type freeze)
3517 as the system sleep state during system startup with
3518 the optional capability to repeat N number of times.
3519 The system is woken from this state using a
3520 wakeup-capable RTC alarm.
David Brownell77437fd2008-07-23 21:28:33 -07003521
Linus Torvalds1da177e2005-04-16 15:20:36 -07003522 thash_entries= [KNL,NET]
3523 Set number of hash buckets for TCP connection
3524
Len Brownf8707ec2007-08-12 00:12:54 -04003525 thermal.act= [HW,ACPI]
3526 -1: disable all active trip points in all thermal zones
3527 <degrees C>: override all lowest active trip points
3528
Len Brownc52a7412007-08-14 15:49:32 -04003529 thermal.crt= [HW,ACPI]
3530 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04003531 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04003532
Len Brownf5487142007-08-12 00:12:44 -04003533 thermal.nocrt= [HW,ACPI]
3534 Set to disable actions on ACPI thermal zone
3535 critical and hot trip points.
3536
Len Brown72b33ef2007-08-12 00:12:17 -04003537 thermal.off= [HW,ACPI]
3538 1: disable ACPI thermal control
3539
Len Browna70cdc52007-08-12 00:12:35 -04003540 thermal.psv= [HW,ACPI]
3541 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08003542 <degrees C>: override all passive trip points to this
3543 value
Len Browna70cdc52007-08-12 00:12:35 -04003544
Len Brown730ff342007-08-12 00:12:26 -04003545 thermal.tzp= [HW,ACPI]
3546 Specify global default ACPI thermal zone polling rate
3547 <deci-seconds>: poll all this frequency
3548 0: no polling (default)
3549
Thomas Gleixner8d32a302011-02-23 23:52:23 +00003550 threadirqs [KNL]
3551 Force threading of all interrupt handlers except those
Masanari Iida24775d62012-02-15 00:26:42 +09003552 marked explicitly IRQF_NO_THREAD.
Thomas Gleixner8d32a302011-02-23 23:52:23 +00003553
Konrad Rzeszutek Wilk2ca62b02013-05-08 17:12:44 -04003554 tmem [KNL,XEN]
3555 Enable the Transcendent memory driver if built-in.
3556
3557 tmem.cleancache=0|1 [KNL, XEN]
3558 Default is on (1). Disable the usage of the cleancache
3559 API to send anonymous pages to the hypervisor.
3560
3561 tmem.frontswap=0|1 [KNL, XEN]
3562 Default is on (1). Disable the usage of the frontswap
Konrad Rzeszutek Wilk37d46e12013-05-14 13:56:42 -04003563 API to send swap pages to the hypervisor. If disabled
3564 the selfballooning and selfshrinking are force disabled.
Konrad Rzeszutek Wilk2ca62b02013-05-08 17:12:44 -04003565
3566 tmem.selfballooning=0|1 [KNL, XEN]
3567 Default is on (1). Disable the driving of swap pages
3568 to the hypervisor.
3569
3570 tmem.selfshrinking=0|1 [KNL, XEN]
3571 Default is on (1). Partial swapoff that immediately
3572 transfers pages from Xen hypervisor back to the
3573 kernel based on different criteria.
3574
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003575 topology= [S390]
3576 Format: {off | on}
3577 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07003578 topology information if the hardware supports this.
3579 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003580 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02003581 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003582
Nishanth Aravamudan2d73bae2014-10-10 09:04:49 -07003583 topology_updates= [KNL, PPC, NUMA]
3584 Format: {off}
3585 Specify if the kernel should ignore (off)
3586 topology updates sent by the hypervisor to this
3587 LPAR.
3588
Linus Torvalds1da177e2005-04-16 15:20:36 -07003589 tp720= [HW,PS2]
3590
Rajiv Andrade225a9be2010-03-25 00:55:32 -03003591 tpm_suspend_pcr=[HW,TPM]
3592 Format: integer pcr id
3593 Specify that at suspend time, the tpm driver
3594 should extend the specified pcr with zeros,
3595 as a workaround for some chips which fail to
3596 flush the last written pcr on TPM_SaveState.
3597 This will guarantee that all the other pcrs
3598 are saved.
3599
Li Zefan9d612be2009-06-24 17:33:15 +08003600 trace_buf_size=nn[KMG]
Joonsoo Kim3e6fb8e2014-12-03 10:39:20 +09003601 [FTRACE] will set tracing buffer size on each cpu.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09003602
Li Zefan020e5f82009-07-01 10:47:05 +08003603 trace_event=[event-list]
3604 [FTRACE] Set and start specified trace events in order
3605 to facilitate early boot debugging.
3606 See also Documentation/trace/events.txt
3607
Steven Rostedt7bcfaf52012-11-01 22:56:07 -04003608 trace_options=[option-list]
3609 [FTRACE] Enable or disable tracer options at boot.
3610 The option-list is a comma delimited list of options
3611 that can be enabled or disabled just as if you were
3612 to echo the option name into
3613
3614 /sys/kernel/debug/tracing/trace_options
3615
3616 For example, to enable stacktrace option (to dump the
3617 stack trace of each event), add to the command line:
3618
3619 trace_options=stacktrace
3620
3621 See also Documentation/trace/ftrace.txt "trace options"
3622 section.
3623
Steven Rostedt (Red Hat)0daa23022014-12-12 22:27:10 -05003624 tp_printk[FTRACE]
3625 Have the tracepoints sent to printk as well as the
3626 tracing ring buffer. This is useful for early boot up
3627 where the system hangs or reboots and does not give the
3628 option for reading the tracing buffer or performing a
3629 ftrace_dump_on_oops.
3630
3631 To turn off having tracepoints sent to printk,
3632 echo 0 > /proc/sys/kernel/tracepoint_printk
3633 Note, echoing 1 into this file without the
3634 tracepoint_printk kernel cmdline option has no effect.
3635
3636 ** CAUTION **
3637
3638 Having tracepoints sent to printk() and activating high
3639 frequency tracepoints such as irq or sched, can cause
3640 the system to live lock.
3641
Steven Rostedt (Red Hat)de7edd32013-06-14 16:21:43 -04003642 traceoff_on_warning
3643 [FTRACE] enable this option to disable tracing when a
3644 warning is hit. This turns off "tracing_on". Tracing can
3645 be enabled again by echoing '1' into the "tracing_on"
3646 file located in /sys/kernel/debug/tracing/
3647
3648 This option is useful, as it disables the trace before
3649 the WARNING dump is called, which prevents the trace to
3650 be filled with content caused by the warning output.
3651
3652 This option can also be set at run time via the sysctl
3653 option: kernel/traceoff_on_warning
3654
Jiri Kosinafcf4d8212012-03-21 16:34:02 -07003655 transparent_hugepage=
3656 [KNL]
3657 Format: [always|madvise|never]
3658 Can be used to control the default behavior of the system
3659 with respect to transparent hugepages.
3660 See Documentation/vm/transhuge.txt for more details.
3661
john stultzd3b8f882009-08-17 16:40:47 -07003662 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07003663 Format: <string>
3664 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07003665 disables clocksource verification at runtime, as well
3666 as the stability checks done at bootup. Used to enable
3667 high-resolution timer mode on older hardware, and in
3668 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07003669 [x86] noirqtime: Do not use TSC to do irq accounting.
3670 Used to run time disable IRQ_TIME_ACCOUNTING on any
3671 platforms where RDTSC is slow and this accounting
3672 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07003673
Randy Dunlapa9913042005-10-23 12:57:11 -07003674 turbografx.map[2|3]= [HW,JOY]
3675 TurboGraFX parallel port interface
3676 Format:
3677 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07003678 See also Documentation/input/joystick-parport.txt
3679
Christian Kujaub6935f82011-05-31 15:22:05 +00003680 udbg-immortal [PPC] When debugging early kernel crashes that
3681 happen after console_init() and before a proper
3682 console driver takes over, this boot options might
3683 help "seeing" what's going on.
3684
Eric Dumazetf86dcc52009-10-07 00:37:59 +00003685 uhash_entries= [KNL,NET]
3686 Set number of hash buckets for UDP/UDP-Lite connections
3687
Alan Stern5f8364b2006-12-05 16:29:55 -05003688 uhci-hcd.ignore_oc=
3689 [USB] Ignore overcurrent events (default N).
3690 Some badly-designed motherboards generate lots of
3691 bogus events, for ports that aren't wired to
3692 anything. Set this parameter to avoid log spamming.
3693 Note that genuine overcurrent events won't be
3694 reported either.
3695
Simon Arlotte3a61b02008-07-19 23:32:54 +01003696 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07003697 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01003698
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02003699 usbcore.authorized_default=
3700 [USB] Default USB device authorization:
3701 (default -1 = authorized except for wireless USB,
3702 0 = not authorized, 1 = authorized)
3703
Alan Sternb5e795f2007-02-20 15:00:53 -05003704 usbcore.autosuspend=
3705 [USB] The autosuspend time delay (in seconds) used
3706 for newly-detected USB devices (default 2). This
3707 is the time required before an idle device will be
3708 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04003709 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05003710
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003711 usbcore.usbfs_snoop=
3712 [USB] Set to log all usbfs traffic (default 0 = off).
3713
3714 usbcore.blinkenlights=
3715 [USB] Set to cycle leds on hubs (default 0 = off).
3716
3717 usbcore.old_scheme_first=
3718 [USB] Start with the old device initialization
3719 scheme (default 0 = off).
3720
Alan Stern3f5eb8d2011-11-17 16:41:35 -05003721 usbcore.usbfs_memory_mb=
3722 [USB] Memory limit (in MB) for buffers allocated by
3723 usbfs (default = 16, 0 = max = 2047).
3724
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003725 usbcore.use_both_schemes=
3726 [USB] Try the other device initialization scheme
3727 if the first one fails (default 1 = enabled).
3728
3729 usbcore.initial_descriptor_timeout=
3730 [USB] Specifies timeout for the initial 64-byte
3731 USB_REQ_GET_DESCRIPTOR request in milliseconds
3732 (default 5000 = 5.0 seconds).
3733
Linus Torvalds1da177e2005-04-16 15:20:36 -07003734 usbhid.mousepoll=
3735 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07003736
Alan Sternd4f373e2008-11-10 14:07:45 -05003737 usb-storage.delay_use=
3738 [UMS] The delay in seconds before a new device is
Mark Knibbs19101952014-11-04 13:00:15 +00003739 scanned for Logical Units (default 1).
Alan Sternd4f373e2008-11-10 14:07:45 -05003740
3741 usb-storage.quirks=
3742 [UMS] A list of quirks entries to supplement or
3743 override the built-in unusual_devs list. List
3744 entries are separated by commas. Each entry has
3745 the form VID:PID:Flags where VID and PID are Vendor
3746 and Product ID values (4-digit hex numbers) and
3747 Flags is a set of characters, each corresponding
3748 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05003749 a = SANE_SENSE (collect more than 18 bytes
3750 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05003751 b = BAD_SENSE (don't collect more than 18
3752 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05003753 c = FIX_CAPACITY (decrease the reported
3754 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01003755 d = NO_READ_DISC_INFO (don't use
3756 READ_DISC_INFO command);
3757 e = NO_READ_CAPACITY_16 (don't use
3758 READ_CAPACITY_16 command);
Hans de Goede734016b2014-09-16 18:36:52 +02003759 f = NO_REPORT_OPCODES (don't use report opcodes
3760 command, uas only);
Alan Sternc838ea42008-12-15 10:40:06 -05003761 h = CAPACITY_HEURISTICS (decrease the
3762 reported device capacity by one
3763 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05003764 i = IGNORE_DEVICE (don't bind to this
3765 device);
3766 l = NOT_LOCKABLE (don't try to lock and
3767 unlock ejectable media);
3768 m = MAX_SECTORS_64 (don't transfer more
3769 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04003770 n = INITIAL_READ10 (force a retry of the
3771 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05003772 o = CAPACITY_OK (accept the capacity
3773 reported by the device);
Namjae Jeoneaa05df2012-07-07 23:05:28 -04003774 p = WRITE_CACHE (the device cache is ON
3775 by default);
Alan Sternd4f373e2008-11-10 14:07:45 -05003776 r = IGNORE_RESIDUE (the device reports
3777 bogus residue values);
3778 s = SINGLE_LUN (the device has only one
3779 Logical Unit);
Hans de Goede59307852014-09-15 16:04:12 +02003780 t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
3781 commands, uas only);
Alan Sternb6089f12014-09-02 15:42:18 -04003782 u = IGNORE_UAS (don't bind to the uas driver);
Alan Sternd4f373e2008-11-10 14:07:45 -05003783 w = NO_WP_DETECT (don't test whether the
3784 medium is write-protected).
3785 Example: quirks=0419:aaf5:rl,0421:0433:rc
3786
Stephen Boydac1667d2011-08-13 12:34:50 -07003787 user_debug= [KNL,ARM]
3788 Format: <int>
3789 See arch/arm/Kconfig.debug help text.
3790 1 - undefined instruction events
3791 2 - system calls
3792 4 - invalid data aborts
3793 8 - SIGSEGV faults
3794 16 - SIGBUS faults
3795 Example: user_debug=31
3796
Ian Campbell14315592010-02-17 10:38:10 +00003797 userpte=
3798 [X86] Flags controlling user PTE allocations.
3799
3800 nohigh = do not allocate PTE pages in
3801 HIGHMEM regardless of setting
3802 of CONFIG_HIGHPTE.
3803
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05303804 vdso= [X86,SH]
Andy Lutomirskib0b49f22014-03-13 16:01:26 -07003805 On X86_32, this is an alias for vdso32=. Otherwise:
3806
3807 vdso=1: enable VDSO (the default)
Ingo Molnare6e54942006-06-27 02:53:50 -07003808 vdso=0: disable VDSO mapping
3809
Andy Lutomirskib0b49f22014-03-13 16:01:26 -07003810 vdso32= [X86] Control the 32-bit vDSO
3811 vdso32=1: enable 32-bit VDSO
3812 vdso32=0 or vdso32=2: disable 32-bit VDSO
3813
3814 See the help text for CONFIG_COMPAT_VDSO for more
3815 details. If CONFIG_COMPAT_VDSO is set, the default is
3816 vdso32=0; otherwise, the default is vdso32=1.
3817
3818 For compatibility with older kernels, vdso32=2 is an
3819 alias for vdso32=0.
3820
3821 Try vdso32=0 if you encounter an error that says:
3822 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
Roland McGrathaf65d642008-01-30 13:30:43 +01003823
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09003824 vector= [IA-64,SMP]
3825 vector=percpu: enable percpu vector domain
3826
Linus Torvalds1da177e2005-04-16 15:20:36 -07003827 video= [FB] Frame buffer configuration
3828 See Documentation/fb/modedb.txt.
3829
Aaron Lu3afe6da2013-06-20 15:08:55 +08003830 video.brightness_switch_enabled= [0,1]
3831 If set to 1, on receiving an ACPI notify event
3832 generated by hotkey, video driver will adjust brightness
3833 level and then send out the event to user space through
3834 the allocated input device; If set to 0, video driver
3835 will only send out the event without touching backlight
3836 brightness level.
Rafael J. Wysocki28437682014-07-14 19:35:45 +02003837 default: 1
Aaron Lu3afe6da2013-06-20 15:08:55 +08003838
Pawel Moll81a054c2012-05-09 18:30:16 +01003839 virtio_mmio.device=
3840 [VMMIO] Memory mapped virtio (platform) device.
3841
3842 <size>@<baseaddr>:<irq>[:<id>]
3843 where:
3844 <size> := size (can use standard suffixes
3845 like K, M and G)
3846 <baseaddr> := physical base address
3847 <irq> := interrupt number (as passed to
3848 request_irq())
3849 <id> := (optional) platform device id
3850 example:
3851 virtio_mmio.device=1K@0x100b0000:48:7
3852
3853 Can be used multiple times for multiple devices.
3854
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003855 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05003856 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07003857 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003858 Use vga=ask for menu.
3859 This is actually a boot loader parameter; the value is
3860 passed to the kernel using a special protocol.
3861
Randy Dunlapa9913042005-10-23 12:57:11 -07003862 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07003863 size of <nn>. This can be used to increase the
3864 minimum size (128MB on x86). It can also be used to
3865 decrease the size and leave more room for directly
3866 mapped kernel RAM.
3867
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003868 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3869 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07003870
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003871 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3872 Format: <command>
3873
3874 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3875 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07003876
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003877 vsyscall= [X86-64]
3878 Controls the behavior of vsyscalls (i.e. calls to
3879 fixed addresses of 0xffffffffff600x00 from legacy
3880 code). Most statically-linked binaries and older
3881 versions of glibc use these calls. Because these
3882 functions are at fixed addresses, they make nice
3883 targets for exploits that can control RIP.
3884
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003885 emulate [default] Vsyscalls turn into traps and are
3886 emulated reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003887
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003888 native Vsyscalls are native syscall instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003889 This is a little bit faster than trapping
3890 and makes a few dynamic recompilers work
3891 better than they would in emulation mode.
3892 It also makes exploits much easier to write.
3893
3894 none Vsyscalls don't work at all. This makes
3895 them quite hard to use for exploits but
3896 might break your system.
3897
Clemens Ladisch3855ae12013-08-04 13:09:50 +02003898 vt.color= [VT] Default text color.
3899 Format: 0xYX, X = foreground, Y = background.
3900 Default: 0x07 = light gray on black.
3901
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08003902 vt.cur_default= [VT] Default cursor shape.
3903 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3904 the parameters of the <Esc>[?A;B;Cc escape sequence;
3905 see VGA-softcursor.txt. Default: 2 = underline.
3906
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003907 vt.default_blu= [VT]
3908 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3909 Change the default blue palette of the console.
3910 This is a 16-member array composed of values
3911 ranging from 0-255.
3912
3913 vt.default_grn= [VT]
3914 Format: <green0>,<green1>,<green2>,...,<green15>
3915 Change the default green palette of the console.
3916 This is a 16-member array composed of values
3917 ranging from 0-255.
3918
3919 vt.default_red= [VT]
3920 Format: <red0>,<red1>,<red2>,...,<red15>
3921 Change the default red palette of the console.
3922 This is a 16-member array composed of values
3923 ranging from 0-255.
3924
3925 vt.default_utf8=
3926 [VT]
3927 Format=<0|1>
3928 Set system-wide default UTF-8 mode for all tty's.
3929 Default is 1, i.e. UTF-8 mode is enabled for all
3930 newly opened terminals.
3931
Matthew Garrettf6c06b62009-11-13 15:14:11 -05003932 vt.global_cursor_default=
3933 [VT]
3934 Format=<-1|0|1>
3935 Set system-wide default for whether a cursor
3936 is shown on new VTs. Default is -1,
3937 i.e. cursors will be created by default unless
3938 overridden by individual drivers. 0 will hide
3939 cursors, 1 will display them.
3940
Clemens Ladisch3855ae12013-08-04 13:09:50 +02003941 vt.italic= [VT] Default color for italic text; 0-15.
3942 Default: 2 = green.
3943
3944 vt.underline= [VT] Default color for underlined text; 0-15.
3945 Default: 3 = cyan.
3946
Randy Dunlap4724ba572010-05-03 11:42:52 -07003947 watchdog timers [HW,WDT] For information on watchdog timers,
3948 see Documentation/watchdog/watchdog-parameters.txt
3949 or other driver-specific files in the
3950 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003951
Tejun Heod55262c2013-04-01 11:23:38 -07003952 workqueue.disable_numa
3953 By default, all work items queued to unbound
3954 workqueues are affine to the NUMA nodes they're
3955 issued on, which results in better behavior in
3956 general. If NUMA affinity needs to be disabled for
3957 whatever reason, this option can be used. Note
3958 that this also can be controlled per-workqueue for
3959 workqueues visible under /sys/bus/workqueue/.
3960
Viresh Kumarcee22a12013-04-08 16:45:40 +05303961 workqueue.power_efficient
3962 Per-cpu workqueues are generally preferred because
3963 they show better performance thanks to cache
3964 locality; unfortunately, per-cpu workqueues tend to
3965 be more power hungry than unbound workqueues.
3966
3967 Enabling this makes the per-cpu workqueues which
3968 were observed to contribute significantly to power
3969 consumption unbound, leading to measurably lower
3970 power usage at the cost of small performance
3971 overhead.
3972
3973 The default value of this parameter is determined by
3974 the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
3975
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003976 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3977 default x2apic cluster mode on platforms
3978 supporting x2apic.
3979
Kuppuswamy Sathyanarayanan712b6aa2013-10-17 15:35:29 -07003980 x86_intel_mid_timer= [X86-32,APBT]
3981 Choose timer option for x86 Intel MID platform.
Jacob Panbb24c472009-09-02 07:37:17 -07003982 Two valid options are apbt timer only and lapic timer
3983 plus one apbt timer for broadcast timer.
Kuppuswamy Sathyanarayanan712b6aa2013-10-17 15:35:29 -07003984 x86_intel_mid_timer=apbt_only | lapic_and_apbt
Jacob Panbb24c472009-09-02 07:37:17 -07003985
Stefano Stabellinic1c54132010-05-14 12:44:30 +01003986 xen_emul_unplug= [HW,X86,XEN]
3987 Unplug Xen emulated devices
3988 Format: [unplug0,][unplug1]
3989 ide-disks -- unplug primary master IDE devices
3990 aux-ide-disks -- unplug non-primary-master IDE devices
3991 nics -- unplug network devices
3992 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01003993 unnecessary -- unplugging emulated devices is
3994 unnecessary even if the host did not respond to
3995 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01003996 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01003997
Konrad Rzeszutek Wilk15a3eac2013-09-25 10:07:20 -04003998 xen_nopvspin [X86,XEN]
3999 Disables the ticketlock slowpath using Xen PV
4000 optimizations.
4001
Konrad Rzeszutek Wilk8d693b92014-07-11 11:51:35 -04004002 xen_nopv [X86]
4003 Disables the PV optimizations forcing the HVM guest to
4004 run as generic HVM guest with no PV drivers.
4005
Linus Torvalds1da177e2005-04-16 15:20:36 -07004006 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07004007 Format:
4008 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07004009
Randy Dunlapa9913042005-10-23 12:57:11 -07004010______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07004011
4012TODO:
4013
Linus Torvalds1da177e2005-04-16 15:20:36 -07004014 Add more DRM drivers.