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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 Dilek89e0b9a2011-12-05 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]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 Start an early, polled-mode console on the 8250/16550
717 UART at the specified I/O port or MMIO address,
718 switching to the matching ttyS device later. The
719 options are the same as for ttyS, above.
Konrad Rzeszutek Wilka2fd6412013-02-25 15:54:09 -0500720 hvc<n> Use the hypervisor console device <n>. This is for
721 both Xen and PowerPC hypervisors.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700723 If the device connected to the port is not a TTY but a braille
724 device, prepend "brl," before the device type, for instance
725 console=brl,ttyS0
726 For now, only VisioBraille is supported.
727
Daniel Mackf324edc2009-06-16 15:33:52 -0700728 consoleblank= [KNL] The console blank (screen saver) timeout in
729 seconds. Defaults to 10*60 = 10mins. A value of 0
730 disables the blank timer.
731
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800732 coredump_filter=
733 [KNL] Change the default value for
734 /proc/<pid>/coredump_filter.
735 See also Documentation/filesystems/proc.txt.
736
Len Brown62027ae2011-04-01 18:13:10 -0400737 cpuidle.off=1 [CPU_IDLE]
738 disable the cpuidle sub-system
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700741 Format:
742 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800744 crashkernel=size[KMG][@offset[KMG]]
745 [KNL] Using kexec, Linux can switch to a 'crash kernel'
746 upon panic. This parameter reserves the physical
747 memory region [offset, offset + size] for that kernel
748 image. If '@offset' is omitted, then a suitable offset
749 is selected automatically. Check
750 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700751
Bernhard Wallefb391592007-10-18 23:41:02 -0700752 crashkernel=range1:size1[,range2:size2,...][@offset]
753 [KNL] Same as above, but depends on the memory
754 in the running system. The syntax of range is
755 start-[end] where start and end are both
756 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800757 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700758
Yinghai Luadbc7422013-04-15 22:23:48 -0700759 crashkernel=size[KMG],high
Yinghai Lu55a20ee2013-04-15 22:23:47 -0700760 [KNL, x86_64] range could be above 4G. Allow kernel
761 to allocate physical memory region from top, so could
762 be above 4G if system have more than 4G ram installed.
763 Otherwise memory region will be allocated below 4G, if
764 available.
765 It will be ignored if crashkernel=X is specified.
Yinghai Luadbc7422013-04-15 22:23:48 -0700766 crashkernel=size[KMG],low
767 [KNL, x86_64] range under 4G. When crashkernel=X,high
768 is passed, kernel could allocate physical memory region
Yinghai Luc729de82013-04-15 22:23:45 -0700769 above 4G, that cause second kernel crash on system
770 that require some amount of low memory, e.g. swiotlb
771 requires at least 64M+32K low memory. Kernel would
772 try to allocate 72M below 4G automatically.
773 This one let user to specify own low range under 4G
774 for second kernel instead.
775 0: to disable low allocation.
Yinghai Luadbc7422013-04-15 22:23:48 -0700776 It will be ignored when crashkernel=X,high is not used
Yinghai Lu55a20ee2013-04-15 22:23:47 -0700777 or memory reserved is below 4G.
Yinghai Luc729de82013-04-15 22:23:45 -0700778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 cs89x0_dma= [HW,NET]
780 Format: <dma>
781
782 cs89x0_media= [HW,NET]
783 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700784
Randy Dunlapa9913042005-10-23 12:57:11 -0700785 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 See header of drivers/s390/block/dasd_devmap.c.
787
788 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
789 (one device per port)
790 Format: <port#>,<type>
791 See also Documentation/input/joystick-parport.txt
792
Thomas Renningera648ec02010-08-06 16:11:02 +0200793 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
794 time. See Documentation/dynamic-debug-howto.txt for
Jim Cromie29e36c92012-04-27 14:30:41 -0600795 details. Deprecated, see dyndbg.
Thomas Renningera648ec02010-08-06 16:11:02 +0200796
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 debug [KNL] Enable kernel debugging (events log level).
798
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700799 debug_locks_verbose=
800 [KNL] verbose self-tests
801 Format=<0|1>
802 Print debugging info while doing the locking API
803 self-tests.
804 We default to 0 (no extra messages), setting it to
805 1 will print _a lot_ more information - normally
806 only useful to kernel developers.
807
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700808 debug_objects [KNL] Enable object debugging
809
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500810 no_debug_objects
811 [KNL] Disable object debugging
812
Stanislaw Gruszkac0a32fc52012-01-10 15:07:28 -0800813 debug_guardpage_minorder=
814 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
815 parameter allows control of the order of pages that will
816 be intentionally kept free (and hence protected) by the
817 buddy allocator. Bigger value increase the probability
818 of catching random memory corruption, but reduce the
819 amount of memory for normal system use. The maximum
820 possible value is MAX_ORDER/2. Setting this parameter
821 to 1 or 2 should be enough to identify most random
822 memory corruption problems caused by bugs in kernel or
823 driver code when a CPU writes to (or reads from) a
824 random memory location. Note that there exists a class
825 of memory corruptions problems caused by buggy H/W or
826 F/W or by drivers badly programing DMA (basically when
827 memory is written at bus level and the CPU MMU is
828 bypassed) which are not detectable by
829 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
830 tracking down these problems.
831
Joonsoo Kim031bc572014-12-12 16:55:52 -0800832 debug_pagealloc=
833 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
834 parameter enables the feature at boot time. In
835 default, it is disabled. We can avoid allocating huge
836 chunk of memory for debug pagealloc if we don't enable
837 it at boot time and the system will work mostly same
838 with the kernel built without CONFIG_DEBUG_PAGEALLOC.
839 on: enable the feature
840
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200841 debugpat [X86] Enable PAT debugging
842
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200843 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 Format: <area>[,<node>]
845 See also Documentation/networking/decnet.txt.
846
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700847 default_hugepagesz=
848 [same as hugepagesz=] The size of the default
849 HugeTLB page size. This is the size represented by
850 the legacy /proc/ hugepages APIs, used for SHM, and
851 default size when mounting hugetlbfs filesystems.
852 Defaults to the default architecture's huge page size
853 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700854
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 dhash_entries= [KNL]
856 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700857
Brian Haleyb0f83b22010-02-04 13:36:50 -0800858 disable= [IPV6]
859 See Documentation/networking/ipv6.txt.
860
HATAYAMA Daisuke151e0c72014-01-15 15:44:58 +0900861 disable_cpu_apicid= [X86,APIC,SMP]
862 Format: <int>
863 The number of initial APIC ID for the
864 corresponding CPU to be disabled at boot,
865 mostly used for the kdump 2nd kernel to
866 disable BSP to wake up multiple CPUs without
867 causing system reset or hang due to sending
868 INIT from AP to BSP.
869
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000870 disable_ddw [PPC/PSERIES]
871 Disable Dynamic DMA Window support. Use this if
872 to workaround buggy firmware.
873
Brian Haleyb0f83b22010-02-04 13:36:50 -0800874 disable_ipv6= [IPV6]
875 See Documentation/networking/ipv6.txt.
876
Yinghai Lu95ffa242008-04-29 03:52:33 -0700877 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700878 The kernel tries to adjust MTRR layout from continuous
879 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700880 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700881
Yinghai Lu093af8d2008-01-30 13:33:32 +0100882 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100883 By default the kernel will trim any uncacheable
884 memory out of your available memory pool based on
885 MTRR settings. This parameter disables that behavior,
886 possibly causing your machine to run very slowly.
887
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530888 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700889 Disable PIN 1 of APIC timer
890 Can be useful to work around chipset bugs.
891
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700892 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
893 this option disables the debugging code at boot.
894
895 dma_debug_entries=<number>
896 This option allows to tune the number of preallocated
897 entries for DMA-API debugging code. One entry is
898 required per DMA-API allocation. Use this if the
899 DMA-API debugging code disables itself because the
900 architectural default is too low.
901
Joerg Roedel1745de52009-05-22 21:49:51 +0200902 dma_debug_driver=<driver_name>
903 With this option the DMA-API debugging driver
904 filter feature can be enabled at boot time. Just
905 pass the driver to filter for as the parameter.
906 The filter can be disabled or changed to another
907 driver later using sysfs.
908
Carsten Emdeda0df922012-03-18 22:37:33 +0100909 drm_kms_helper.edid_firmware=[<connector>:]<file>
910 Broken monitors, graphic adapters and KVMs may
911 send no or incorrect EDID data sets. This parameter
912 allows to specify an EDID data set in the
913 /lib/firmware directory that is used instead.
914 Generic built-in EDID data sets are used, if one of
915 edid/1024x768.bin, edid/1280x1024.bin,
916 edid/1680x1050.bin, or edid/1920x1080.bin is given
917 and no file with the same name exists. Details and
918 instructions how to build your own EDID data are
919 available in Documentation/EDID/HOWTO.txt. An EDID
920 data set will only be used for a particular connector,
921 if its name and a colon are prepended to the EDID
922 name.
923
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 dscc4.setup= [NET]
925
Jim Cromie29e36c92012-04-27 14:30:41 -0600926 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
927 module.dyndbg[="val"]
928 Enable debug messages at boot time. See
929 Documentation/dynamic-debug-howto.txt for details.
930
Mark Salter56aeeba2014-04-07 15:39:53 -0700931 early_ioremap_debug [KNL]
932 Enable debug messages in early_ioremap support. This
933 is useful for tracking down temporary early mappings
934 which are not unmapped.
935
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700936 earlycon= [KNL] Output early console device and options.
Rob Herring0d3c6732014-04-18 17:19:57 -0500937
Michal Simek6fa62fc2014-09-10 12:43:02 +0200938 cdns,<addr>
939 Start an early, polled-mode console on a cadence serial
940 port at the specified address. The cadence serial port
941 must already be setup and configured. Options are not
942 yet supported.
943
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700944 uart[8250],io,<addr>[,options]
945 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700946 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700947 Start an early, polled-mode console on the 8250/16550
948 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700949 MMIO inter-register address stride is either 8-bit
950 (mmio) or 32-bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700951 The options are the same as for ttyS, above.
952
Rob Herring0d3c6732014-04-18 17:19:57 -0500953 pl011,<addr>
954 Start an early, polled-mode console on a pl011 serial
955 port at the specified address. The pl011 serial port
956 must already be setup and configured. Options are not
957 yet supported.
958
Stephen Boyd0efe7292014-09-15 17:22:51 -0700959 msm_serial,<addr>
960 Start an early, polled-mode console on an msm serial
961 port at the specified address. The serial port
962 must already be setup and configured. Options are not
963 yet supported.
964
965 msm_serial_dm,<addr>
966 Start an early, polled-mode console on an msm serial
967 dm port at the specified address. The serial port
968 must already be setup and configured. Options are not
969 yet supported.
970
Rob Herringd50d7262014-04-18 17:19:58 -0500971 smh Use ARM semihosting calls for early console.
972
Tomasz Figab94ba032015-01-23 14:47:41 +0100973 s3c2410,<addr>
974 s3c2412,<addr>
975 s3c2440,<addr>
976 s3c6400,<addr>
977 s5pv210,<addr>
978 exynos4210,<addr>
979 Use early console provided by serial driver available
980 on Samsung SoCs, requires selecting proper type and
981 a correct base address of the selected UART port. The
982 serial port must already be setup and configured.
983 Options are not yet supported.
984
Finn Thain7913ad12014-04-12 23:48:56 +1000985 earlyprintk= [X86,SH,BLACKFIN,ARM,M68k]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 earlyprintk=vga
Matt Fleming72548e82013-10-04 09:36:56 +0100987 earlyprintk=efi
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -0500988 earlyprintk=xen
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 earlyprintk=serial[,ttySn[,baudrate]]
Dave Hansen147ea092013-04-10 14:03:38 -0700990 earlyprintk=serial[,0x...[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500991 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500992 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993
Dave Hansen147ea092013-04-10 14:03:38 -0700994 earlyprintk is useful when the kernel crashes before
995 the normal console is initialized. It is not enabled by
996 default because it has some cosmetic problems.
997
Randy Dunlapa9913042005-10-23 12:57:11 -0700998 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 takes over.
1000
Matt Fleming72548e82013-10-04 09:36:56 +01001001 Only one of vga, efi, serial, or usb debug port can
1002 be used at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003
Dave Hansen147ea092013-04-10 14:03:38 -07001004 Currently only ttyS0 and ttyS1 may be specified by
1005 name. Other I/O ports may be explicitly specified
1006 on some architectures (x86 and arm at least) by
1007 replacing ttySn with an I/O port address, like this:
1008 earlyprintk=serial,0x1008,115200
1009 You can find the port for a given device in
1010 /proc/tty/driver/serial:
1011 2: uart:ST16650V2 port:00001008 irq:18 ...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012
1013 Interaction with the standard serial driver is not
1014 very good.
1015
Matt Fleming72548e82013-10-04 09:36:56 +01001016 The VGA and EFI output is eventually overwritten by
1017 the real console.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -05001019 The xen output can only be used by Xen PV guests.
1020
Chen, Gongc700f012013-12-06 01:17:08 -05001021 edac_report= [HW,EDAC] Control how to report EDAC event
1022 Format: {"on" | "off" | "force"}
1023 on: enable EDAC to report H/W event. May be overridden
1024 by other higher priority error reporting module.
1025 off: disable H/W event reporting through EDAC.
1026 force: enforce the use of EDAC to report H/W event.
1027 default: on.
1028
Jason Wessel97311912010-05-20 21:04:30 -05001029 ekgdboc= [X86,KGDB] Allow early kernel console debugging
1030 ekgdboc=kbd
1031
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001032 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -05001033 the boot argument: earlyprintk=vga
1034
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -07001036 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001038 efi= [EFI]
Borislav Petkovfed6cef2015-02-05 11:44:41 +01001039 Format: { "old_map", "nochunk", "noruntime", "debug" }
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001040 old_map [X86-64]: switch to the old ioremap-based EFI
1041 runtime services mapping. 32-bit still uses this one by
1042 default.
Matt Fleming5a17dae2014-08-05 11:52:11 +01001043 nochunk: disable reading files in "chunks" in the EFI
1044 boot stub, as chunking can cause problems with some
1045 firmware implementations.
Dave Young5ae36832014-08-14 17:15:28 +08001046 noruntime : disable EFI runtime services support
Borislav Petkovfed6cef2015-02-05 11:44:41 +01001047 debug: enable misc debug output
Borislav Petkovd2f7cbe2013-10-31 17:25:08 +01001048
Richard Weinberger8c58bf32013-04-17 01:00:53 +02001049 efi_no_storage_paranoia [EFI; X86]
1050 Using this parameter you can use more than 50% of
1051 your efi variable storage. Use this parameter only if
1052 you are really sure that your UEFI does sane gc and
1053 fulfills the spec otherwise your board may brick.
1054
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 eisa_irq_edge= [PARISC,HW]
1056 See header of drivers/parisc/eisa.c.
1057
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001058 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -07001060 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061
1062 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +01001063 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +02001064 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07001065 Documentation/block/deadline-iosched.txt for details.
1066
Michael Holzheud3bf37952011-10-30 15:16:37 +01001067 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -07001068 Specifies physical address of start of kernel core
Michael Holzheud3bf37952011-10-30 15:16:37 +01001069 image elf header and optionally the size. Generally
1070 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -08001071 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001073 enable_mtrr_cleanup [X86]
1074 The kernel tries to adjust MTRR layout from continuous
1075 to discrete, to make X server driver able to add WB
1076 entry later. This parameter enables that.
1077
Randy Dunlapca1eda22009-05-06 16:02:58 -07001078 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001079 Enable PIN 1 of APIC timer
1080 Can be useful to work around chipset bugs
1081 (in particular on some ATI chipsets).
1082 The kernel tries to set a reasonable default.
1083
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 enforcing [SELINUX] Set initial enforcing status.
1085 Format: {"0" | "1"}
1086 See security/selinux/Kconfig help text.
1087 0 -- permissive (log only, no denials).
1088 1 -- enforcing (deny and log).
1089 Default value is 0.
1090 Value can be changed at runtime via /selinux/enforce.
1091
Huang Yinga08f82d2010-05-18 14:35:21 +08001092 erst_disable [ACPI]
1093 Disable Error Record Serialization Table (ERST)
1094 support.
1095
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 ether= [HW,NET] Ethernet cards parameters
1097 This option is obsoleted by the "netdev=" option, which
1098 has equivalent usage. See its documentation for details.
1099
Mimi Zohar7102ebc2011-05-12 18:33:20 -04001100 evm= [EVM]
1101 Format: { "fix" }
1102 Permit 'security.evm' to be updated regardless of
1103 current integrity status.
1104
Akinobu Mitade1ba092006-12-08 02:39:42 -08001105 failslab=
1106 fail_page_alloc=
1107 fail_make_request=[KNL]
1108 General fault injection mechanism.
1109 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +02001110 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -08001111
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001113 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Alex Chiangf13ae302008-05-08 14:03:23 -06001115 force_pal_cache_flush
1116 [IA-64] Avoid check_sal_cache_flush which may hang on
1117 buggy SAL_CACHE_FLUSH implementations. Using this
1118 parameter will force ia64_sal_cache_flush to call
1119 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1120
Chris Bainbridge69f23662014-03-07 18:40:42 +07001121 forcepae [X86-32]
1122 Forcefully enable Physical Address Extension (PAE).
1123 Many Pentium M systems disable PAE but may have a
1124 functionally usable PAE implementation.
1125 Warning: use of this parameter will taint the kernel
1126 and may cause unknown problems.
1127
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001128 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -04001129 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001130 as early as possible in order to facilitate early
1131 boot debugging.
1132
Frederic Weisbeckercecbca92010-04-18 19:08:41 +02001133 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -04001134 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +02001135 If no parameter is passed, ftrace will dump
1136 buffers of all CPUs, but if you pass orig_cpu, it will
1137 dump only the buffer of the CPU that triggered the
1138 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -04001139
1140 ftrace_filter=[function-list]
1141 [FTRACE] Limit the functions traced by the function
1142 tracer at boot up. function-list is a comma separated
1143 list of functions. This list can be changed at run
1144 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -07001145 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -04001146
1147 ftrace_notrace=[function-list]
1148 [FTRACE] Do not trace the functions specified in
1149 function-list. This list can be changed at run time
1150 by the set_ftrace_notrace file in the debugfs
1151 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +01001152
Stefan Assmann369bc182009-10-12 22:17:21 +02001153 ftrace_graph_filter=[function-list]
1154 [FTRACE] Limit the top level callers functions traced
1155 by the function graph tracer at boot up.
1156 function-list is a comma separated list of functions
1157 that can be changed at run time by the
1158 set_graph_function file in the debugfs tracing directory.
1159
Namhyung Kim0d7d9a12014-06-13 01:23:50 +09001160 ftrace_graph_notrace=[function-list]
1161 [FTRACE] Do not trace from the functions specified in
1162 function-list. This list is a comma separated list of
1163 functions that can be changed at run time by the
1164 set_graph_notrace file in the debugfs tracing directory.
1165
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 gamecon.map[2|3]=
1167 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1168 support via parallel port (up to 5 devices per port)
1169 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1170 See also Documentation/input/joystick-parport.txt
1171
1172 gamma= [HW,DRM]
1173
Yinghai Luaaf23042008-01-30 13:33:09 +01001174 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
1175 Format: off | on
1176 default: on
1177
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -07001178 gcov_persist= [GCOV] When non-zero (default), profiling data for
1179 kernel modules is saved and remains accessible via
1180 debugfs, even when the module is unloaded/reloaded.
1181 When zero, profiling data is discarded and associated
1182 debugfs files are removed at module unload time.
1183
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 gpt [EFI] Forces disk with valid GPT signature but
Davidlohr Bueso6c5de792014-01-23 15:56:03 -08001185 invalid Protective MBR to be treated as GPT. If the
1186 primary GPT is corrupted, it enables the backup/alternate
1187 GPT to be used instead.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188
Andreas Larsson6cec9b02012-11-15 08:47:14 +01001189 grcan.enable0= [HW] Configuration of physical interface 0. Determines
1190 the "Enable 0" bit of the configuration register.
1191 Format: 0 | 1
1192 Default: 0
1193 grcan.enable1= [HW] Configuration of physical interface 1. Determines
1194 the "Enable 0" bit of the configuration register.
1195 Format: 0 | 1
1196 Default: 0
1197 grcan.select= [HW] Select which physical interface to use.
1198 Format: 0 | 1
1199 Default: 0
1200 grcan.txsize= [HW] Sets the size of the tx buffer.
1201 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1202 Default: 1024
1203 grcan.rxsize= [HW] Sets the size of the rx buffer.
1204 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1205 Default: 1024
1206
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 hashdist= [KNL,NUMA] Large hashes allocated during boot
1208 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -07001209 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -07001210 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211
1212 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1213
1214 hd= [EIDE] (E)IDE hard drive subsystem geometry
1215 Format: <cyl>,<head>,<sect>
1216
Huang Yingea8c0712010-05-18 14:35:15 +08001217 hest_disable [ACPI]
1218 Disable Hardware Error Source Table (HEST) support;
1219 corresponding firmware-first mode error processing
1220 logic will be disabled.
1221
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
1223 size of <nn>. This works even on boxes that have no
1224 highmem otherwise. This also works to reduce highmem
1225 size on bigger boxes.
1226
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -08001227 highres= [KNL] Enable/disable high resolution timer mode.
1228 Valid parameters: "on", "off"
1229 Default: "on"
1230
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 hisax= [HW,ISDN]
1232 See Documentation/isdn/README.HiSax.
1233
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001234 hlt [BUGS=ARM,SH]
1235
1236 hpet= [X86-32,HPET] option to control HPET usage
1237 Format: { enable (default) | disable | force |
1238 verbose }
1239 disable: disable HPET and use PIT instead
1240 force: allow force enabled of undocumented chips (ICH4,
1241 VIA, nVidia)
1242 verbose: show contents of HPET registers during setup
1243
Prarit Bhargava3d035f52013-11-12 15:08:33 -08001244 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1245 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1246
Andi Kleenb4718e62008-07-23 21:27:51 -07001247 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1248 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -07001249 On x86-64 and powerpc, this option can be specified
1250 multiple times interleaved with hugepages= to reserve
1251 huge pages of different sizes. Valid pages sizes on
1252 x86-64 are 2M (when the CPU supports "pse") and 1G
Luiz Capitulino27ec26e2014-12-12 16:55:18 -08001253 (when the CPU supports the "pdpe1gb" cpuinfo flag).
Paul Mundt6902aa82008-09-21 17:14:42 +09001254
Hendrik Brueckner555d61d2009-01-09 12:15:02 +01001255 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
1256 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +01001257 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1258 If specified, z/VM IUCV HVC accepts connections
1259 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +01001260
James Hoganfdabf522012-10-09 11:00:27 +01001261 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
1262 hardware thread id mappings.
1263 Format: <cpu>:<hwthread>
1264
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07001265 keep_bootcon [KNL]
1266 Do not unregister boot console at start. This is only
1267 useful for debugging when something happens in the window
1268 between unregistering the boot console and initializing
1269 the real console.
1270
Jarkko Nikula3a853fb2009-03-23 18:07:47 -07001271 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -07001272 or register an additional I2C bus that is not
1273 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -07001274 Format:
1275 <bus_id>,<clkrate>
1276
Jiri Kosina36d95732008-10-06 02:51:09 -04001277 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +02001279 i8042.dumbkbd [HW] Pretend that controller can only read data from
1280 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281 (Don't attempt to blink the leds)
1282 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -05001283 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -04001284 i8042.noloop [HW] Disable the AUX Loopback command while probing
1285 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 i8042.nomux [HW] Don't check presence of an active multiplexing
Dmitry Torokhove55a3362014-10-31 09:35:53 -07001287 controller
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1289 controllers
Masanari Iida24775d62012-02-15 00:26:42 +09001290 i8042.notimeout [HW] Ignore timeout condition signalled by controller
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 i8042.reset [HW] Reset the controller during init and cleanup
1292 i8042.unlock [HW] Unlock (ignore) the keylock
Srihari Vijayaraghavan148e9a72015-01-07 16:25:53 -08001293 i8042.kbdreset [HW] Reset device connected to KBD port
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294
1295 i810= [HW,DRM]
1296
Dmitry Torokhove70c9d52005-06-25 14:54:25 -07001297 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1298 indicates that the driver is running on unsupported
1299 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1301 does not match list of supported models.
1302 i8k.power_status
1303 [HW] Report power status in /proc/i8k
1304 (disabled by default)
1305 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1306 capability is set.
1307
Carsten Emde4dca20e2012-03-15 15:56:26 +01001308 i915.invert_brightness=
Carsten Emde7bd90902012-03-15 15:56:25 +01001309 [DRM] Invert the sense of the variable that is used to
1310 set the brightness of the panel backlight. Normally a
Carsten Emde4dca20e2012-03-15 15:56:26 +01001311 brightness value of 0 indicates backlight switched off,
1312 and the maximum of the brightness value sets the backlight
1313 to maximum brightness. If this parameter is set to 0
1314 (default) and the machine requires it, or this parameter
1315 is set to 1, a brightness value of 0 sets the backlight
1316 to maximum brightness, and the maximum of the brightness
1317 value switches the backlight off.
1318 -1 -- never invert brightness
1319 0 -- machine default
1320 1 -- force brightness inversion
Carsten Emde7bd90902012-03-15 15:56:25 +01001321
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 icn= [HW,ISDN]
1323 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1324
David Fries0af80c02009-02-25 20:28:21 +01001325 ide-core.nodma= [HW] (E)IDE subsystem
1326 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +02001327 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1328 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +01001329 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Maciej W. Rozycki0f8b7f52014-10-25 17:03:52 +01001331 ide-generic.probe-mask= [HW] (E)IDE subsystem
1332 Format: <int>
1333 Probe mask for legacy ISA IDE ports. Depending on
1334 platform up to 6 ports are supported, enabled by
1335 setting corresponding bits in the mask to 1. The
1336 default value is 0x0, which has a special meaning.
1337 On systems that have PCI, it triggers scanning the
1338 PCI bus for the first and the second port, which
1339 are then probed. On systems without PCI the value
1340 of 0x0 enables probing the two first ports as if it
1341 was 0x3.
1342
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001343 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1344 Claim all unknown PCI IDE storage controllers.
1345
Andi Kleenf039b752007-05-02 19:27:12 +02001346 idle= [X86]
Len Brown69fb3672013-02-10 01:38:39 -05001347 Format: idle=poll, idle=halt, idle=nomwait
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001348 Poll forces a polling idle loop that can slightly
1349 improve the performance of waking up a idle CPU, but
1350 will use a lot of power and make the system run hot.
1351 Not recommended.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001352 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +08001353 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001354 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -07001355
Ingo Molnar792908222006-12-06 20:40:51 -08001356 ignore_loglevel [KNL]
1357 Ignore loglevel setting - this will print /all/
1358 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001359 We also add it as printk module parameter, so users
1360 could change it dynamically, usually by
1361 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -08001362
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 ihash_entries= [KNL]
1364 Set number of hash buckets for inode cache.
1365
Mimi Zohar2fe5d6d2012-02-13 10:15:05 -05001366 ima_appraise= [IMA] appraise integrity measurements
Dmitry Kasatkin2faa6ef2014-05-08 13:11:29 +03001367 Format: { "off" | "enforce" | "fix" | "log" }
Mimi Zohar2fe5d6d2012-02-13 10:15:05 -05001368 default: "enforce"
1369
Mimi Zohar07f6a792011-03-09 22:25:48 -05001370 ima_appraise_tcb [IMA]
1371 The builtin appraise policy appraises all files
1372 owned by uid=0.
1373
Mimi Zohar3323eec92009-02-04 09:06:58 -05001374 ima_hash= [IMA]
Mimi Zohare7a2ad72013-06-07 12:16:37 +02001375 Format: { md5 | sha1 | rmd160 | sha256 | sha384
1376 | sha512 | ... }
Mimi Zohar3323eec92009-02-04 09:06:58 -05001377 default: "sha1"
1378
Mimi Zohare7a2ad72013-06-07 12:16:37 +02001379 The list of supported hash algorithms is defined
1380 in crypto/hash_info.h.
1381
Eric Paris5789ba32009-05-21 15:47:06 -04001382 ima_tcb [IMA]
1383 Load a policy which meets the needs of the Trusted
1384 Computing Base. This means IMA will measure all
1385 programs exec'd, files mmap'd for exec, and all files
1386 opened for read by uid=0.
1387
Roberto Sassu9b9d4ce2013-06-07 12:16:35 +02001388 ima_template= [IMA]
1389 Select one of defined IMA measurements template formats.
1390 Formats: { "ima" | "ima-ng" }
1391 Default: "ima-ng"
1392
Roberto Sassuc2426d22014-10-13 14:08:42 +02001393 ima_template_fmt=
1394 [IMA] Define a custom template format.
1395 Format: { "field1|...|fieldN" }
1396
Dmitry Kasatkin3bcced32014-02-26 17:05:20 +02001397 ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1398 Format: <min_file_size>
1399 Set the minimal file size for using asynchronous hash.
1400 If left unspecified, ahash usage is disabled.
1401
1402 ahash performance varies for different data sizes on
1403 different crypto accelerators. This option can be used
1404 to achieve the best performance for a particular HW.
1405
Dmitry Kasatkin6edf7a82014-05-06 14:47:13 +03001406 ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1407 Format: <bufsize>
1408 Set hashing buffer size. Default: 4k.
1409
1410 ahash performance varies for different chunk sizes on
1411 different crypto accelerators. This option can be used
1412 to achieve best performance for particular HW.
1413
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 init= [KNL]
1415 Format: <full_path>
1416 Run specified binary instead of /sbin/init as init
1417 process.
1418
1419 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1420 for working out where the kernel is dying during
1421 startup.
1422
Prarit Bhargava7b0b73d2014-06-04 16:12:17 -07001423 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1424 initcall functions. Useful for debugging built-in
1425 modules and initcalls.
1426
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 initrd= [BOOT] Specify the location of the initial ramdisk
1428
1429 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1430 Format: <irq>
1431
Fenghua Yu6bb2ff82013-05-21 15:35:17 -04001432 int_pln_enable [x86] Enable power limit notification interrupt
1433
Mimi Zohard726d8d2013-03-18 14:48:02 -04001434 integrity_audit=[IMA]
1435 Format: { "0" | "1" }
1436 0 -- basic integrity auditing messages. (Default)
1437 1 -- additional integrity auditing messages.
1438
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001439 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001440 on
1441 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001442 off
1443 Disable intel iommu driver.
1444 igfx_off [Default Off]
1445 By default, gfx is mapped as normal device. If a gfx
1446 device has a dedicated DMAR unit, the DMAR unit is
1447 bypassed by not enabling DMAR with this option. In
1448 this case, gfx device will use physical address for
1449 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001450 forcedac [x86_64]
1451 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001452 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001453 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001454 than 32-bit addressing. The default is to look
1455 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001456 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001457 strict [Default Off]
1458 With this option on every unmap_single operation will
1459 result in a hardware IOTLB flush operation as opposed
1460 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001461 sp_off [Default Off]
1462 By default, super page will be supported if Intel IOMMU
1463 has the capability. With this option, super page will
1464 not be supported.
Masanari Iida2e92c7a2011-12-15 01:18:52 +09001465
1466 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1467 0 disables intel_idle and fall back on acpi_idle.
1468 1 to 6 specify maximum depth of C-state.
1469
Dirk Brandewie6be26492013-02-15 22:55:10 +01001470 intel_pstate= [X86]
1471 disable
1472 Do not enable intel_pstate as the default
1473 scaling driver for the supported processors
Ethan Zhaoaa4ea342014-12-09 10:43:19 +09001474 force
1475 Enable intel_pstate on systems that prohibit it by default
1476 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1477 instead of acpi-cpufreq may disable platform features, such
1478 as thermal controls and power capping, that rely on ACPI
1479 P-States information being indicated to OSPM and therefore
1480 should be used with caution. This option does not work with
1481 processors that aren't supported by the intel_pstate driver
1482 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
Dirk Brandewie2f86dc42014-11-06 09:40:47 -08001483 no_hwp
1484 Do not enable hardware P state control (HWP)
1485 if available.
Kristen Carlson Accardid64c3b02015-02-06 13:41:55 -08001486 hwp_only
1487 Only load intel_pstate on systems which support
1488 hardware P state control (HWP) if available.
Dirk Brandewie6be26492013-02-15 22:55:10 +01001489
Chris Wrightd1423d52010-07-20 11:06:49 -07001490 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001491 on enable Interrupt Remapping (default)
1492 off disable Interrupt Remapping
1493 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001494 no_x2apic_optout
1495 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001496
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001497 iomem= Disable strict checking of access to MMIO memory
1498 strict regions from userspace.
1499 relaxed
1500
1501 iommu= [x86]
1502 off
1503 force
1504 noforce
1505 biomerge
1506 panic
1507 nopanic
1508 merge
1509 nomerge
1510 forcesac
1511 soft
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001512 pt [x86, IA-64]
Thadeu Lima de Souza Cascardo4e287842014-10-23 19:19:35 -02001513 nobypass [PPC/POWERNV]
1514 Disable IOMMU bypass, using IOMMU for PCI devices.
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001515
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001516
1517 io7= [HW] IO7 for Marvel based alpha systems
1518 See comment before marvel_specify_io7 in
1519 arch/alpha/kernel/core_marvel.c.
1520
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301521 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001522 0x80
1523 Standard port 0x80 based delay
1524 0xed
1525 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001526 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001527 Simple two microseconds delay
1528 none
1529 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001532 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
Alan Cox200803d2005-06-28 20:45:18 -07001534 irqfixup [HW]
1535 When an interrupt is not handled search all handlers
1536 for it. Intended to get systems with badly broken
1537 firmware running.
1538
1539 irqpoll [HW]
1540 When an interrupt is not handled search all handlers
1541 for it. Also check all handlers each timer
1542 interrupt. Intended to get systems with badly broken
1543 firmware running.
1544
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001546 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547
1548 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001549 Format:
1550 <cpu number>,...,<cpu number>
1551 or
Li Zefanb225d442008-11-06 12:53:39 -08001552 <cpu number>-<cpu number>
1553 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001554 or a mixture
1555 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001556
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 This option can be used to specify one or more CPUs
1558 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001559 algorithms. You can move a process onto or off an
1560 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 <cpu number> begins at 0 and the maximum value is
1562 "number of CPUs in system - 1".
1563
1564 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001565 alternative -- manually setting the CPU mask of all
1566 tasks in the system -- can cause problems and
1567 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568
Randy Dunlapa9913042005-10-23 12:57:11 -07001569 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
Joerg Roedel7d8bfa22013-04-09 21:27:19 +02001571 ivrs_ioapic [HW,X86_64]
1572 Provide an override to the IOAPIC-ID<->DEVICE-ID
1573 mapping provided in the IVRS ACPI table. For
1574 example, to map IOAPIC-ID decimal 10 to
1575 PCI device 00:14.0 write the parameter as:
1576 ivrs_ioapic[10]=00:14.0
1577
1578 ivrs_hpet [HW,X86_64]
1579 Provide an override to the HPET-ID<->DEVICE-ID
1580 mapping provided in the IVRS ACPI table. For
1581 example, to map HPET-ID decimal 0 to
1582 PCI device 00:14.0 write the parameter as:
1583 ivrs_hpet[0]=00:14.0
1584
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 js= [HW,JOY] Analog joystick
1586 See Documentation/input/joystick.txt.
1587
Kees Cook24f2e022014-06-13 13:30:36 -07001588 kaslr/nokaslr [X86]
1589 Enable/disable kernel and module base offset ASLR
1590 (Address Space Layout Randomization) if built into
1591 the kernel. When CONFIG_HIBERNATION is selected,
1592 kASLR is disabled by default. When kASLR is enabled,
1593 hibernation will be disabled.
1594
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001595 keepinitrd [HW,ARM]
1596
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301597 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001598 specifies the amount of memory usable by the kernel
1599 for non-movable allocations. The requested amount is
1600 spread evenly throughout all nodes in the system. The
1601 remaining memory in each node is used for Movable
1602 pages. In the event, a node is too small to have both
1603 kernelcore and Movable pages, kernelcore pages will
1604 take priority and other nodes will have a larger number
Weiping Pan675217f2013-09-30 13:45:10 -07001605 of Movable pages. The Movable zone is used for the
Mel Gormaned7ed362007-07-17 04:03:14 -07001606 allocation of pages that may be reclaimed or moved
1607 by the page migration subsystem. This means that
1608 HugeTLB pages may not be allocated from this zone.
1609 Note that allocations like PTEs-from-HighMem still
1610 use the HighMem zone if it exists, and the Normal
1611 zone if it does not.
1612
Jason Wessel4fe1da42010-05-20 21:04:31 -05001613 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1614 Format: <Controller#>[,poll interval]
1615 The controller # is the number of the ehci usb debug
1616 port as it is probed via PCI. The poll interval is
1617 optional and is the number seconds in between
1618 each poll cycle to the debug port in case you need
1619 the functionality for interrupting the kernel with
1620 gdb or control-c on the dbgp connection. When
1621 not using this parameter you use sysrq-g to break into
1622 the kernel debugger.
1623
Jason Wessel84c08fd2010-05-20 21:04:24 -05001624 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001625 Requires a tty driver that supports console polling,
1626 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001627 Serial only format: <serial_device>[,baud]
1628 keyboard only format: kbd
1629 keyboard and serial format: kbd,<serial_device>[,baud]
1630 Optional Kernel mode setting:
1631 kms, kbd format: kms,kbd
1632 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001633
Jason Wessel84c08fd2010-05-20 21:04:24 -05001634 kgdbwait [KGDB] Stop kernel execution and enter the
1635 kernel debugger at the earliest opportunity.
1636
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001637 kmac= [MIPS] korina ethernet MAC address.
1638 Configure the RouterBoard 532 series on-chip
1639 Ethernet adapter MAC address.
1640
Catalin Marinas04f70332009-06-11 13:22:39 +01001641 kmemleak= [KNL] Boot-time kmemleak enable/disable
1642 Valid arguments: on, off
1643 Default: on
Masanari Iida47aeedd2014-10-24 21:24:59 +09001644 Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
1645 the default is off.
Catalin Marinas04f70332009-06-11 13:22:39 +01001646
Xishi Qiuc3ac14b2014-01-23 15:53:33 -08001647 kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode
1648 Valid arguments: 0, 1, 2
1649 kmemcheck=0 (disabled)
1650 kmemcheck=1 (enabled)
1651 kmemcheck=2 (one-shot mode)
1652 Default: 2 (one-shot mode)
1653
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301654 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001655 in oops dumps.
1656
Andre Przywarafef07aa2009-07-10 14:20:35 +02001657 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1658 Default is 0 (don't ignore, but inject #GP)
1659
Xiao Guangronga182d872010-09-20 22:17:48 +08001660 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1661 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001662 Default is 0 (off)
1663
Andre Przywarafef07aa2009-07-10 14:20:35 +02001664 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001665 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001666
1667 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1668 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001669 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001670
Andre Przywarafef07aa2009-07-10 14:20:35 +02001671 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1672 (virtualized MMU) support on capable Intel chips.
1673 Default is 1 (enabled)
1674
1675 kvm-intel.emulate_invalid_guest_state=
1676 [KVM,Intel] Enable emulation of invalid guest states
1677 Default is 0 (disabled)
1678
1679 kvm-intel.flexpriority=
1680 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1681 Default is 1 (enabled)
1682
Sasha Levine1a72ae2011-08-09 14:28:35 +03001683 kvm-intel.nested=
1684 [KVM,Intel] Enable VMX nesting (nVMX).
1685 Default is 0 (disabled)
1686
Andre Przywarafef07aa2009-07-10 14:20:35 +02001687 kvm-intel.unrestricted_guest=
1688 [KVM,Intel] Disable unrestricted guest feature
1689 (virtualized real and unpaged mode) on capable
1690 Intel chips. Default is 1 (enabled)
1691
1692 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1693 feature (tagged TLBs) on capable Intel chips.
1694 Default is 1 (enabled)
1695
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 l2cr= [PPC]
1697
Robert Brosea78bfbf2008-03-29 07:20:23 +11001698 l3cr= [PPC]
1699
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001700 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001701 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702
Suresh Siddha279f1462012-10-22 14:37:58 -07001703 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1704 value for LAPIC timer one-shot implementation. Default
1705 back to the programmable timer unit in the LAPIC.
1706
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301707 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001708 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001709
FD Camifcb71f62008-01-06 19:08:56 +01001710 libata.dma= [LIBATA] DMA control
1711 libata.dma=0 Disable all PATA and SATA DMA
1712 libata.dma=1 PATA and SATA Disk DMA only
1713 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001714 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001715 Combinations also work, so libata.dma=3 enables DMA
1716 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001717
Michael Prokop20308872009-08-06 00:14:10 +02001718 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1719 libata.ignore_hpa=0 keep BIOS limits (default)
1720 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001721
Dave Jones78e70c22007-09-27 11:50:13 -04001722 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1723 when set.
1724 Format: <int>
1725
Tejun Heo33267322008-02-13 09:15:09 +09001726 libata.force= [LIBATA] Force configurations. The format is comma
1727 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001728 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001729 matching port, link or device. Basically, it matches
1730 the ATA ID string printed on console by libata. If
1731 the whole ID part is omitted, the last PORT and DEVICE
1732 values are used. If ID hasn't been specified yet, the
1733 configuration applies to all ports, links and devices.
1734
1735 If only DEVICE is omitted, the parameter applies to
1736 the port and all links and devices behind it. DEVICE
1737 number of 0 either selects the first device or the
1738 first fan-out link behind PMP device. It does not
1739 select the host link. DEVICE number of 15 selects the
1740 host link and device attached to it.
1741
1742 The VAL specifies the configuration to force. As long
1743 as there's no ambiguity shortcut notation is allowed.
1744 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1745 The following configurations can be forced.
1746
1747 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1748 Any ID with matching PORT is used.
1749
1750 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1751
1752 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1753 udma[/][16,25,33,44,66,100,133] notation is also
1754 allowed.
1755
1756 * [no]ncq: Turn on or off NCQ.
1757
Tejun Heo05944bd2008-08-13 20:19:09 +09001758 * nohrst, nosrst, norst: suppress hard, soft
1759 and both resets.
1760
Dan Williamsca6d43b2012-06-21 23:41:41 -07001761 * rstonce: only attempt one reset during
1762 hot-unplug link recovery
1763
Tejun Heo43c9c592010-05-23 12:59:11 +02001764 * dump_id: dump IDENTIFY data.
1765
Vincent Pelletier966fbe12013-05-21 22:30:58 +02001766 * atapi_dmadir: Enable ATAPI DMADIR bridge support
1767
Robin H. Johnsonb8bd6dc2013-12-16 09:31:19 -08001768 * disable: Disable this device.
1769
Tejun Heo33267322008-02-13 09:15:09 +09001770 If there are multiple matching configurations changing
1771 the same attribute, the last one is used.
1772
Yinghai Lu95f72d12010-07-12 14:36:09 +10001773 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001774
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001776 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001778 lockd.nlm_grace_period=P [NFS] Assign grace period.
1779 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001781 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1782 Format: <integer>
1783
1784 lockd.nlm_timeout=T [NFS] Assign timeout value.
1785 Format: <integer>
1786
1787 lockd.nlm_udpport=M [NFS] Assign UDP port.
1788 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789
Paul E. McKenneyec4518a2014-09-12 10:50:01 -07001790 locktorture.nreaders_stress= [KNL]
1791 Set the number of locking read-acquisition kthreads.
1792 Defaults to being automatically set based on the
1793 number of online CPUs.
1794
1795 locktorture.nwriters_stress= [KNL]
1796 Set the number of locking write-acquisition kthreads.
1797
1798 locktorture.onoff_holdoff= [KNL]
1799 Set time (s) after boot for CPU-hotplug testing.
1800
1801 locktorture.onoff_interval= [KNL]
1802 Set time (s) between CPU-hotplug operations, or
1803 zero to disable CPU-hotplug testing.
1804
1805 locktorture.shuffle_interval= [KNL]
1806 Set task-shuffle interval (jiffies). Shuffling
1807 tasks allows some CPUs to go into dyntick-idle
1808 mode during the locktorture test.
1809
1810 locktorture.shutdown_secs= [KNL]
1811 Set time (s) after boot system shutdown. This
1812 is useful for hands-off automated testing.
1813
1814 locktorture.stat_interval= [KNL]
1815 Time (s) between statistics printk()s.
1816
1817 locktorture.stutter= [KNL]
1818 Time (s) to stutter testing, for example,
1819 specifying five seconds causes the test to run for
1820 five seconds, wait for five seconds, and so on.
1821 This tests the locking primitive's ability to
1822 transition abruptly to and from idle.
1823
1824 locktorture.torture_runnable= [BOOT]
1825 Start locktorture running at boot time.
1826
1827 locktorture.torture_type= [KNL]
1828 Specify the locking implementation to test.
1829
1830 locktorture.verbose= [KNL]
1831 Enable additional printk() statements.
1832
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1834 Format: <irq>
1835
1836 loglevel= All Kernel Messages with a loglevel smaller than the
1837 console loglevel will be printed to the console. It can
1838 also be changed with klogd or other programs. The
1839 loglevels are defined as follows:
1840
1841 0 (KERN_EMERG) system is unusable
1842 1 (KERN_ALERT) action must be taken immediately
1843 2 (KERN_CRIT) critical conditions
1844 3 (KERN_ERR) error conditions
1845 4 (KERN_WARNING) warning conditions
1846 5 (KERN_NOTICE) normal but significant condition
1847 6 (KERN_INFO) informational
1848 7 (KERN_DEBUG) debug-level messages
1849
Randy Dunlapc756d082011-02-20 20:08:35 -08001850 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
Luis R. Rodriguez23b28992014-08-06 16:08:56 -07001851 in bytes. n must be a power of two and greater
1852 than the minimal size. The minimal size is defined
1853 by LOG_BUF_SHIFT kernel config parameter. There is
1854 also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
1855 that allows to increase the default size depending on
1856 the number of CPUs. See init/Kconfig for more details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857
Randy Dunlapaccaa242007-10-16 01:29:37 -07001858 logo.nologo [FB] Disables display of the built-in Linux logo.
1859 This may be used to provide more screen space for
1860 kernel log messages and is useful when debugging
1861 kernel boot problems.
1862
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 lp=0 [LP] Specify parallel ports to use, e.g,
1864 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1865 lp=reset first parallel port). 'lp=0' disables the
1866 lp=auto printer driver. 'lp=reset' (which can be
1867 specified in addition to the ports) causes
1868 attached printers to be reset. Using
1869 lp=port1,port2,... specifies the parallel ports
1870 to associate lp devices with, starting with
1871 lp0. A port specification may be 'none' to skip
1872 that lp device, or a parport name such as
1873 'parport0'. Specifying 'lp=auto' instead of a
1874 port specification list means that device IDs
1875 from each port should be examined, to see if
1876 an IEEE 1284-compliant printer is attached; if
1877 so, the driver will manage that printer.
1878 See also header of drivers/char/lp.c.
1879
1880 lpj=n [KNL]
1881 Sets loops_per_jiffy to given constant, thus avoiding
1882 time-consuming boot-time autodetection (up to 250 ms per
1883 CPU). 0 enables autodetection (default). To determine
1884 the correct value for your kernel, boot with normal
1885 autodetection and see what value is printed. Note that
1886 on SMP systems the preset will be applied to all CPUs,
1887 which is likely to cause problems if your CPUs need
1888 significantly divergent settings. An incorrect value
1889 will cause delays in the kernel to be wrong, leading to
1890 unpredictable I/O errors and other breakage. Although
1891 unlikely, in the extreme case this might damage your
1892 hardware.
1893
1894 ltpc= [NET]
1895 Format: <io>,<irq>,<dma>
1896
Randy Dunlap16290242011-08-13 12:34:52 -07001897 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001898 (machvec) in a generic kernel.
1899 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900
Wu Zhangjin3209e702009-07-02 23:27:12 +08001901 machtype= [Loongson] Share the same kernel image file between different
1902 yeeloong laptop.
1903 Example: machtype=lemote-yeeloong-2f-7inch
1904
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001905 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1906 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907
1908 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001909 should make use of. maxcpus=n : n >= 0 limits the
1910 kernel to using 'n' processors. n=0 is a special case,
1911 it is equivalent to "nosmp", which also disables
1912 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913
Kay Sieversd134b002011-07-31 22:08:04 +02001914 max_loop= [LOOP] The number of loop block devices that get
1915 (loop.max_loop) unconditionally pre-created at init time. The default
1916 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1917 of statically allocating a predefined number, loop
1918 devices can be requested on-demand with the
1919 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001920
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001921 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922
Uwe Hermann71cced62008-10-20 09:32:21 -07001923 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001924
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 md= [HW] RAID subsystems devices and level
1926 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001927
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 mdacon= [MDA]
1929 Format: <first>,<last>
1930 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001931
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1933 Amount of memory to be used when the kernel is not able
1934 to see the whole system memory or for test.
Wen Congyangfbb97d82012-12-17 15:59:29 -08001935 [X86] Work as limiting max address. Use together
1936 with memmap= to avoid physical address space collisions.
1937 Without memmap= PCI devices could be placed at addresses
1938 belonging to unused RAM.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001940 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 memory.
1942
Paul Mundt6902aa82008-09-21 17:14:42 +09001943 memchunk=nn[KMG]
1944 [KNL,SH] Allow user to override the default size for
1945 per-device physically contiguous DMA buffers.
1946
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301947 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 E820 memory map, as specified by the user.
1949 Such memmap=exactmap lines can be constructed based on
1950 BIOS output or other requirements. See the memmap=nn@ss
1951 option description.
1952
1953 memmap=nn[KMG]@ss[KMG]
Randy Dunlap277cba12014-02-06 12:04:19 -08001954 [KNL] Force usage of a specific region of memory.
1955 Region of memory to be used is from ss to ss+nn.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956
1957 memmap=nn[KMG]#ss[KMG]
1958 [KNL,ACPI] Mark specific memory as ACPI data.
Randy Dunlap277cba12014-02-06 12:04:19 -08001959 Region of memory to be marked is from ss to ss+nn.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960
1961 memmap=nn[KMG]$ss[KMG]
1962 [KNL,ACPI] Mark specific memory as reserved.
Randy Dunlap277cba12014-02-06 12:04:19 -08001963 Region of memory to be reserved is from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001964 Example: Exclude memory from 0x18690000-0x1869ffff
1965 memmap=64K$0x18690000
1966 or
1967 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001969 memory_corruption_check=0/1 [X86]
1970 Some BIOSes seem to corrupt the first 64k of
1971 memory when doing things like suspend/resume.
1972 Setting this option will scan the memory
1973 looking for corruption. Enabling this will
1974 both detect corruption and prevent the kernel
1975 from using the memory being corrupted.
1976 However, its intended as a diagnostic tool; if
1977 repeatable BIOS-originated corruption always
1978 affects the same memory, you can use memmap=
1979 to prevent the kernel from using that memory.
1980
1981 memory_corruption_check_size=size [X86]
1982 By default it checks for corruption in the low
1983 64k, making this memory unavailable for normal
1984 use. Use this parameter to scan for
1985 corruption in more or less memory.
1986
1987 memory_corruption_check_period=seconds [X86]
1988 By default it checks for corruption every 60
1989 seconds. Use this parameter to check at some
1990 other rate. 0 disables periodic checking.
1991
Vladimir Murzine4b0db72015-04-14 15:48:43 -07001992 memtest= [KNL,X86,ARM] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001993 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001994 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001995 Specifies the number of memtest passes to be
1996 performed. Each pass selects another test
1997 pattern from a given set of patterns. Memtest
1998 fills the memory with this pattern, validates
1999 memory contents and reserves bad memory
2000 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07002001
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002 meye.*= [HW] Set MotionEye Camera parameters
2003 See Documentation/video4linux/meye.txt.
2004
Andres Salomon8f368812007-10-12 23:04:06 +02002005 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2006 Multi-Function General Purpose Timers on AMD Geode
2007 platforms.
2008
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01002009 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2010 the BIOS has incorrectly applied a workaround. TinyBIOS
2011 version 0.98 is known to be affected, 0.99 fixes the
2012 problem by letting the user disable the workaround.
2013
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 mga= [HW,DRM]
2015
Randy Dunlap1c207f92008-11-19 15:36:16 -08002016 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
2017 physical address is ignored.
2018
Michel Pollet39f45d72009-05-20 11:10:31 +01002019 mini2440= [ARM,HW,KNL]
2020 Format:[0..2][b][c][t]
2021 Default: "0tb"
2022 MINI2440 configuration specification:
2023 0 - The attached screen is the 3.5" TFT
2024 1 - The attached screen is the 7" TFT
2025 2 - The VGA Shield is attached (1024x768)
2026 Leaving out the screen size parameter will not load
2027 the TFT driver, and the framebuffer will be left
2028 unconfigured.
2029 b - Enable backlight. The TFT backlight pin will be
2030 linked to the kernel VESA blanking code and a GPIO
2031 LED. This parameter is not necessary when using the
2032 VGA shield.
2033 c - Enable the s3c camera interface.
2034 t - Reserved for enabling touchscreen support. The
2035 touchscreen support is not enabled in the mainstream
2036 kernel as of 2.6.30, a preliminary port can be found
2037 in the "bleeding edge" mini2440 support kernel at
2038 http://repo.or.cz/w/linux-2.6/mini2440.git
2039
Mel Gorman6b74ab92008-07-23 21:26:49 -07002040 mminit_loglevel=
2041 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2042 parameter allows control of the logging verbosity for
2043 the additional memory initialisation checks. A value
2044 of 0 disables mminit logging and a level of 4 will
2045 log everything. Information is printed at KERN_DEBUG
2046 so loglevel=8 may also need to be specified.
2047
Rusty Russell106a4ee2012-09-26 10:09:40 +01002048 module.sig_enforce
2049 [KNL] When CONFIG_MODULE_SIG is set, this means that
2050 modules without (valid) signatures will fail to load.
Paul Bolle2a039be2013-03-25 20:42:06 +01002051 Note that if CONFIG_MODULE_SIG_FORCE is set, that
Rusty Russell106a4ee2012-09-26 10:09:40 +01002052 is always true, so this option does nothing.
2053
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054 mousedev.tap_time=
2055 [MOUSE] Maximum time between finger touching and
2056 leaving touchpad surface for touch to be considered
2057 a tap and be reported as a left button click (for
2058 touchpads working in absolute mode only).
2059 Format: <msecs>
2060 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
2061 reporting absolute coordinates, such as tablets
2062 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
2063 reporting absolute coordinates, such as tablets
2064
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302065 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002066 is similar to kernelcore except it specifies the
2067 amount of memory used for migratable allocations.
2068 If both kernelcore and movablecore is specified,
2069 then kernelcore will be at *least* the specified
2070 value but may be more. If movablecore on its own
2071 is specified, the administrator must be careful
2072 that the amount of memory usable for all allocations
2073 is not too small.
2074
Tang Chenc5320922013-11-12 15:08:10 -08002075 movable_node [KNL,X86] Boot-time switch to enable the effects
2076 of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
2077
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 MTD_Partition= [MTD]
2079 Format: <name>,<region-number>,<size>,<offset>
2080
Randy Dunlapa9913042005-10-23 12:57:11 -07002081 MTD_Region= [MTD] Format:
2082 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
2084 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07002085 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002086
Will Schmidt4e89a2d2010-09-28 15:33:12 +00002087 multitce=off [PPC] This parameter disables the use of the pSeries
2088 firmware feature for updating multiple TCE entries
2089 at a time.
2090
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07002091 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
2092
2093 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2094
2095 boundary - index of last SLC block on Flex-OneNAND.
2096 The remaining blocks are configured as MLC blocks.
2097 lock - Configure if Flex-OneNAND boundary should be locked.
2098 Once locked, the boundary cannot be changed.
2099 1 indicates lock status, 0 indicates unlock status.
2100
Ben Dooks9db829f2008-07-03 11:24:29 +01002101 mtdset= [ARM]
2102 ARM/S3C2412 JIVE boot control
2103
2104 See arch/arm/mach-s3c2412/mach-jive.c
2105
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07002107 [HW] Make the MicroTouch USB driver use raw coordinates
2108 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002110 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02002111 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002112 that could hold holes aka. UC entries.
2113
2114 mtrr_gran_size=nn[KMG] [X86]
2115 Used for mtrr cleanup. It is granularity of mtrr block.
2116 Default is 1.
2117 Large value could prevent small alignment from
2118 using up MTRRs.
2119
2120 mtrr_spare_reg_nr=n [X86]
2121 Format: <integer>
2122 Range: 0,7 : spare reg number
2123 Default : 1
2124 Used for mtrr cleanup. It is spare mtrr entries number.
2125 Set to 2 or more if your graphical card needs more.
2126
Linus Torvalds1da177e2005-04-16 15:20:36 -07002127 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
2128
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 netdev= [NET] Network devices parameters
2130 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2131 Note that mem_start is often overloaded to mean
2132 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07002133 This usage is only documented in each driver source
2134 file if at all.
2135
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07002136 nf_conntrack.acct=
2137 [NETFILTER] Enable connection tracking flow accounting
2138 0 to disable accounting
2139 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02002140 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07002141
Chuck Lever306a0752010-09-17 10:54:37 -04002142 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04002143 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144
2145 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04002146 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147
Chuck Lever306a0752010-09-17 10:54:37 -04002148 nfsrootdebug [NFS] enable nfsroot debugging messages.
2149 See Documentation/filesystems/nfs/nfsroot.txt.
2150
Trond Myklebusta72b4422006-01-03 09:55:41 +01002151 nfs.callback_tcpport=
2152 [NFS] set the TCP port on which the NFSv4 callback
2153 channel should listen.
2154
Trond Myklebuste571cbf2009-08-19 18:12:27 -04002155 nfs.cache_getent=
2156 [NFS] sets the pathname to the program which is used
2157 to update the NFS client cache entries.
2158
2159 nfs.cache_getent_timeout=
2160 [NFS] sets the timeout after which an attempt to
2161 update a cache entry is deemed to have failed.
2162
Trond Myklebust58df0952006-01-03 09:55:57 +01002163 nfs.idmap_cache_timeout=
2164 [NFS] set the maximum lifetime for idmapper cache
2165 entries.
2166
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04002167 nfs.enable_ino64=
2168 [NFS] enable 64-bit inode numbers.
2169 If zero, the NFS client will fake up a 32-bit inode
2170 number for the readdir() and stat() syscalls instead
2171 of returning the full 64-bit number.
2172 The default is to return 64-bit inode numbers.
2173
Trond Myklebustef159e92012-02-06 19:50:40 -05002174 nfs.max_session_slots=
2175 [NFSv4.1] Sets the maximum number of session slots
2176 the client will attempt to negotiate with the server.
2177 This limits the number of simultaneous RPC requests
2178 that the client can send to the NFSv4.1 server.
2179 Note that there is little point in setting this
2180 value higher than the max_tcp_slot_table_limit.
2181
Trond Myklebustb064eca22011-02-22 15:44:32 -08002182 nfs.nfs4_disable_idmapping=
Trond Myklebust074b1d12012-01-09 13:46:26 -05002183 [NFSv4] When set to the default of '1', this option
2184 ensures that both the RPC level authentication
2185 scheme and the NFS level operations agree to use
2186 numeric uids/gids if the mount is using the
2187 'sec=sys' security flavour. In effect it is
2188 disabling idmapping, which can make migration from
2189 legacy NFSv2/v3 systems to NFSv4 easier.
2190 Servers that do not support this mode of operation
2191 will be autodetected by the client, and it will fall
2192 back to using the idmapper.
2193 To turn off this behaviour, set the value to '0'.
Chuck Lever6f2ea7f2012-09-14 17:24:41 -04002194 nfs.nfs4_unique_id=
2195 [NFS4] Specify an additional fixed unique ident-
2196 ification string that NFSv4 clients can insert into
2197 their nfs_client_id4 string. This is typically a
2198 UUID that is generated at system install time.
Trond Myklebustb064eca22011-02-22 15:44:32 -08002199
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002200 nfs.send_implementation_id =
2201 [NFSv4.1] Send client implementation identification
2202 information in exchange_id requests.
2203 If zero, no implementation identification information
2204 will be sent.
2205 The default is to send the implementation identification
2206 information.
Trond Myklebustf6de7a32013-09-04 10:08:54 -04002207
2208 nfs.recover_lost_locks =
2209 [NFSv4] Attempt to recover locks that were lost due
2210 to a lease timeout on the server. Please note that
2211 doing this risks data corruption, since there are
2212 no guarantees that the file will remain unchanged
2213 after the locks are lost.
2214 If you want to enable the kernel legacy behaviour of
2215 attempting to recover these locks, then set this
2216 parameter to '1'.
2217 The default parameter value of '0' causes the kernel
2218 not to attempt recovery of lost locks.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002219
J. Bruce Fieldse9541ce2012-03-22 16:07:18 -04002220 nfsd.nfs4_disable_idmapping=
2221 [NFSv4] When set to the default of '1', the NFSv4
2222 server will return only numeric uids and gids to
2223 clients using auth_sys, and will accept numeric uids
2224 and gids from such clients. This is intended to ease
2225 migration from NFSv2/v3.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05002226
Sachin Bhamare18d98f62012-03-19 20:47:58 -07002227 objlayoutdriver.osd_login_prog=
2228 [NFS] [OBJLAYOUT] sets the pathname to the program which
2229 is used to automatically discover and login into new
2230 osd-targets. Please see:
2231 Documentation/filesystems/pnfs.txt for more explanations
2232
Paul Mundt1e1030d2009-09-01 17:38:32 +09002233 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02002234 when a NMI is triggered.
2235 Format: [state][,regs][,debounce][,die]
2236
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302237 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07002238 Format: [panic,][nopanic,][num]
Ulrich Obergfell195daf62015-04-14 15:44:13 -07002239 Valid num: 0 or 1
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03002240 0 - turn nmi_watchdog off
Ulrich Obergfell195daf62015-04-14 15:44:13 -07002241 1 - turn nmi_watchdog on
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002242 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07002243 timeout occurs (or 'nopanic' to override the opposite
2244 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002245 This is useful when you use a panic=... timeout and
2246 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247
Anton Vorontsovbff38772009-07-08 11:10:56 -07002248 netpoll.carrier_timeout=
2249 [NET] Specifies amount of time (in seconds) that
2250 netpoll should wait for a carrier. By default netpoll
2251 waits 4 seconds.
2252
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002253 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254 emulation library even if a 387 maths coprocessor
2255 is present.
2256
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002257 no_console_suspend
2258 [HW] Never suspend the console
2259 Disable suspending of consoles during suspend and
2260 hibernate operations. Once disabled, debugging
2261 messages can reach various consoles while the rest
2262 of the system is being put to sleep (ie, while
2263 debugging driver suspend/resume hooks). This may
2264 not work reliably with all consoles, but is known
2265 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07002266 To facilitate more flexible debugging, we also add
2267 console_suspend, a printk module parameter to control
2268 it. Users could use console_suspend (usually
2269 /sys/module/printk/parameters/console_suspend) to
2270 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002271
Christoph Lameterc1aee212007-05-31 00:40:47 -07002272 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
2273 caches in the slab allocator. Saves per-node memory,
2274 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08002275
Randy Dunlapa9913042005-10-23 12:57:11 -07002276 noalign [KNL,ARM]
2277
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278 noapic [SMP,APIC] Tells the kernel to not make use of any
2279 IOAPICs that may be present in the system.
2280
Mike Galbraith5091faa2010-11-30 14:18:03 +01002281 noautogroup Disable scheduler automatic task group creation.
2282
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283 nobats [PPC] Do not use BATs for mapping kernel lowmem
2284 on "Classic" PPC cores.
2285
2286 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07002287
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002288 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
2289
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07002290 nodelayacct [KNL] Disable per-task delay accounting
2291
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
2293
Paul Mundt6902aa82008-09-21 17:14:42 +09002294 nodsp [SH] Disable hardware DSP at boot time.
2295
Dave Youngb2e0a542014-08-14 17:15:26 +08002296 noefi Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01002297
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298 noexec [IA-64]
2299
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302300 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002301 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002303 noexec=off: disable non-executable mappings
2304
H. Peter Anvin52b61792012-09-21 12:43:13 -07002305 nosmap [X86]
2306 Disable SMAP (Supervisor Mode Access Prevention)
2307 even if it is supported by processor.
2308
Fenghua Yude5397a2011-05-11 16:51:05 -07002309 nosmep [X86]
H. Peter Anvin52b61792012-09-21 12:43:13 -07002310 Disable SMEP (Supervisor Mode Execution Prevention)
Fenghua Yude5397a2011-05-11 16:51:05 -07002311 even if it is supported by processor.
2312
Jiri Slabyf5a1b192008-04-12 10:28:25 +02002313 noexec32 [X86-64]
2314 This affects only 32-bit executables.
2315 noexec32=on: enable non-executable mappings (default)
2316 read doesn't imply executable mappings
2317 noexec32=off: disable non-executable mappings
2318 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319
Paul Mundt6902aa82008-09-21 17:14:42 +09002320 nofpu [SH] Disable hardware FPU at boot time.
2321
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002322 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08002323 register save and restore. The kernel will only save
2324 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325
Toshi Kani0ddab1d2015-04-14 15:47:20 -07002326 nohugeiomap [KNL,x86] Disable kernel huge I/O mappings.
2327
Suresh Siddha0c752a92009-05-22 12:17:45 -07002328 noxsave [BUGS=X86] Disables x86 extended register state save
2329 and restore using xsave. The kernel will fallback to
2330 enabling legacy floating-point and sse state.
2331
Fenghua Yub6f42a42014-05-29 11:12:31 -07002332 noxsaveopt [X86] Disables xsaveopt used in saving x86 extended
2333 register states. The kernel will fall back to use
2334 xsave to save the states. By using this parameter,
2335 performance of saving the states is degraded because
2336 xsave doesn't support modified optimization while
2337 xsaveopt supports it on xsaveopt enabled systems.
2338
2339 noxsaves [X86] Disables xsaves and xrstors used in saving and
2340 restoring x86 extended register state in compacted
2341 form of xsave area. The kernel will fall back to use
2342 xsaveopt and xrstor to save and restore the states
2343 in standard form of xsave area. By using this
2344 parameter, xsave area per process might occupy more
2345 memory on xsaves enabled systems.
2346
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002347 eagerfpu= [X86]
Suresh Siddhae0022982012-09-10 10:32:32 -07002348 on enable eager fpu restore
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002349 off disable eager fpu restore
Suresh Siddhae0022982012-09-10 10:32:32 -07002350 auto selects the default scheme, which automatically
2351 enables eagerfpu restore for xsaveopt.
Suresh Siddha5d2bd702012-09-06 14:58:52 -07002352
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01002353 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2354 wfi(ARM) instruction doesn't work correctly and not to
2355 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07002356
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06002357 no_file_caps Tells the kernel not to honor file capabilities. The
2358 only way then for a file to be executed with privilege
2359 is to be setuid root or executed by root.
2360
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 nohalt [IA-64] Tells the kernel not to use the power saving
2362 function PAL_HALT_LIGHT when idle. This increases
2363 power-consumption. On the positive side, it reduces
2364 interrupt wake-up latency, which may improve performance
2365 in certain environments such as networked servers or
2366 real-time systems.
2367
Kees Cooka6e15a32014-06-13 13:30:35 -07002368 nohibernate [HIBERNATION] Disable hibernation and resume.
2369
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08002370 nohz= [KNL] Boottime enable/disable dynamic ticks
2371 Valid arguments: on, off
2372 Default: on
2373
Frederic Weisbeckerc5bfece2013-04-12 16:45:34 +02002374 nohz_full= [KNL,BOOT]
2375 In kernels built with CONFIG_NO_HZ_FULL=y, set
Frederic Weisbeckera8318812012-12-18 17:32:19 +01002376 the specified list of CPUs whose tick will be stopped
Frederic Weisbecker0453b432013-03-27 02:18:34 +01002377 whenever possible. The boot CPU will be forced outside
2378 the range to maintain the timekeeping.
Frederic Weisbeckerd1e43fa2013-03-26 23:47:24 +01002379 The CPUs in this range must also be included in the
2380 rcu_nocbs= set.
Frederic Weisbeckera8318812012-12-18 17:32:19 +01002381
Paul Mundteeee7852009-04-02 12:31:16 +09002382 noiotrap [SH] Disables trapped I/O port accesses.
2383
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002384 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385 disable unhandled interrupt sources.
2386
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302387 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01002388 broken timer IRQ sources.
2389
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390 noisapnp [ISAPNP] Disables ISA PnP code.
2391
2392 noinitrd [RAM] Tells the kernel not to load any configured
2393 initial RAM disk.
2394
Weidong Han03ea8152009-04-17 16:42:15 +08002395 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
2396 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07002397 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08002398
Linus Torvalds1da177e2005-04-16 15:20:36 -07002399 nointroute [IA-64]
2400
Randy Dunlap16290242011-08-13 12:34:52 -07002401 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07002402
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02002403 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
2404
Gleb Natapovfd10cde2010-10-14 11:22:51 +02002405 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
2406 fault handling.
2407
Glauber Costad910f5c2011-07-11 15:28:19 -04002408 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
2409 steal time is computed, but won't influence scheduler
2410 behaviour
2411
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002412 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002413
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002414 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08002415
Linus Torvalds1da177e2005-04-16 15:20:36 -07002416 noltlbs [PPC] Do not use large page/tlb entries for kernel
2417 lowmem mapping on PPC40x.
2418
Horms312f1f02006-02-22 09:57:55 +09002419 nomca [IA-64] Disable machine check abort handling
2420
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002421 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02002422
Andres Salomon83d73842007-10-12 23:04:06 +02002423 nomfgpt [X86-32] Disable Multi-Function General Purpose
2424 Timer usage (for AMD Geode machines).
2425
Don Zickusbda62632011-10-13 15:14:27 -04002426 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
2427 shutdown the other cpus. Instead use the REBOOT_VECTOR
2428 irq.
2429
Dave Young02608be2012-02-01 10:33:14 +08002430 nomodule Disable module load
2431
Jiri Kosina016ddd92010-01-18 17:05:40 +01002432 nopat [X86] Disable PAT (page attribute table extension of
2433 pagetables) support.
2434
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002435 norandmaps Don't use address space randomization. Equivalent to
2436 echo 0 > /proc/sys/kernel/randomize_va_space
2437
Jiri Kosinabbff2162010-08-11 18:34:09 +02002438 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02002439
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002440 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002441 with UP alternatives
2442
H. Peter Anvin7a5091d2014-05-11 20:25:20 -07002443 nordrand [X86] Disable kernel use of the RDRAND and
2444 RDSEED instructions even if they are supported
2445 by the processor. RDRAND and RDSEED are still
2446 available to user space applications.
H. Peter Anvin49d859d2011-07-31 14:02:19 -07002447
Randy Dunlapa9913042005-10-23 12:57:11 -07002448 noresume [SWSUSP] Disables resume and restores original swap
2449 space.
2450
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451 no-scroll [VGA] Disables scrollback.
2452 This is required for the Braillex ib80-piezo Braille
2453 reader made by F.H. Papenmeier (Germany).
2454
2455 nosbagart [IA-64]
2456
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002457 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08002458
Len Brown61ec7562007-08-16 03:34:22 -04002459 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
2460 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461
Dave Jones97842212007-07-15 23:41:05 -07002462 nosoftlockup [KNL] Disable the soft-lockup detector.
2463
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464 nosync [HW,M68K] Disables sync negotiation for all devices.
2465
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002466 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467
2468 nousb [USB] Disable the USB subsystem
2469
Ulrich Obergfell195daf62015-04-14 15:44:13 -07002470 nowatchdog [KNL] Disable both lockup detectors, i.e.
2471 soft-lockup and NMI watchdog (hard-lockup).
Don Zickus58687ac2010-05-07 17:11:44 -04002472
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07002474
Weidong Han2b2fd872009-04-17 16:42:12 +08002475 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2476
Fenghua Yuf78cff42012-11-13 11:32:38 -08002477 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2478 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2479 Some features depend on CPU0. Known dependencies are:
2480 1. Resume from suspend/hibernate depends on CPU0.
2481 Suspend/hibernate will fail if CPU0 is offline and you
2482 need to online CPU0 before suspend/hibernate.
2483 2. PIC interrupts also depend on CPU0. CPU0 can't be
2484 removed if a PIC interrupt is detected.
2485 It's said poweroff/reboot may depend on CPU0 on some
2486 machines although I haven't seen such issues so far
2487 after CPU0 is offline on a few tested machines.
2488 If the dependencies are under your control, you can
2489 turn on cpu0_hotplug.
2490
Randy Dunlap16290242011-08-13 12:34:52 -07002491 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07002492 purges which is reported from either PAL_VM_SUMMARY or
2493 SAL PALO.
2494
Yinghai Lu2b633e32010-02-10 01:20:37 -08002495 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2496 could support. nr_cpus=n : n >= 1 limits the kernel to
2497 supporting 'n' processors. Later in runtime you can not
2498 use hotplug cpu feature to put more cpu back to online.
2499 just like you compile the kernel NR_CPUS=n
2500
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002501 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2502
Mel Gorman1a687c22012-11-22 11:16:36 +00002503 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2504 Allowed values are enable and disable
2505
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07002506 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2507 one of ['zone', 'node', 'default'] can be specified
2508 This can be set from sysctl after boot.
2509 See Documentation/sysctl/vm.txt for details.
2510
Randy Dunlap7c4be2532009-01-06 14:42:44 -08002511 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2512 See Documentation/debugging-via-ohci1394.txt for more
2513 info.
2514
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07002515 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2516 Rather than timing out after 20 ms if an EC
2517 command is not properly ACKed, override the length
2518 of the timeout. We have interrupts disabled while
2519 waiting for the ACK, so if this is set too high
2520 interrupts *may* be lost!
2521
Tony Lindgren15ac7af2009-12-11 16:16:32 -08002522 omap_mux= [OMAP] Override bootloader pin multiplexing.
2523 Format: <mux_mode0.mode_name=value>...
2524 For example, to override I2C bus2:
2525 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2526
Linus Torvalds1da177e2005-04-16 15:20:36 -07002527 oprofile.timer= [HW]
2528 Use timer interrupt instead of performance counters
2529
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002530 oprofile.cpu_type= Force an oprofile cpu type
2531 This might be useful if you have an older oprofile
2532 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02002533 Format: { arch_perfmon }
2534 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002535 perfmon on Intel CPUs instead of the
2536 CPU specific event set.
Robert Richter159a80b2011-10-11 19:39:16 +02002537 timer: [X86] Force use of architectural NMI
2538 timer mode (see also oprofile.timer
2539 for generic hr timer mode)
Andreas Krebbeldd3c4672011-11-25 20:03:05 +01002540 [s390] Force legacy basic mode sampling
2541 (report cpu_type "timer")
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02002542
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002543 oops=panic Always panic on oopses. Default is to just kill the
2544 process, but there is a small probability of
2545 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07002546 This will also cause panics on machine check exceptions.
2547 Useful together with panic=30 to trigger a reboot.
2548
Randy Dunlapbcfde332010-06-07 17:10:38 -07002549 OSS [HW,OSS]
2550 See Documentation/sound/oss/oss-parameters.txt
2551
Joonsoo Kim48c96a32014-12-12 16:56:01 -08002552 page_owner= [KNL] Boot-time page_owner enabling option.
2553 Storage of the information about who allocated
2554 each page is disabled in default. With this switch,
2555 we can turn it on.
2556 on: enable the feature
2557
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002558 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07002559 timeout > 0: seconds before rebooting
2560 timeout = 0: wait forever
2561 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562 Format: <timeout>
2563
Prarit Bhargava9e3961a2014-12-10 15:45:50 -08002564 panic_on_warn panic() instead of WARN(). Useful to cause kdump
2565 on a WARN().
2566
Masami Hiramatsuf06e5152014-06-06 14:37:07 -07002567 crash_kexec_post_notifiers
2568 Run kdump after running panic-notifiers and dumping
2569 kmsg. This only for the users who doubt kdump always
2570 succeeds in any situation.
2571 Note that this also increases risks of kdump failure,
2572 because some panic notifiers can make the crashed
2573 kernel more unstable.
2574
Linus Torvalds1da177e2005-04-16 15:20:36 -07002575 parkbd.port= [HW] Parallel port number the keyboard adapter is
2576 connected to, default is 0.
2577 Format: <parport#>
2578 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2579 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07002580 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581
Randy Dunlapa9913042005-10-23 12:57:11 -07002582 parport= [HW,PPT] Specify parallel ports. 0 disables.
2583 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2584 Use 'auto' to force the driver to use any
2585 IRQ/DMA settings detected (the default is to
2586 ignore detected IRQ/DMA settings because of
2587 possible conflicts). You can specify the base
2588 address, IRQ, and DMA settings; IRQ and DMA
2589 should be numbers, or 'auto' (for using detected
2590 settings on that particular port), or 'nofifo'
2591 (to avoid using a FIFO even if it is detected).
2592 Parallel ports are assigned in the order they
2593 are specified on the command line, starting
2594 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595
Randy Dunlapa9913042005-10-23 12:57:11 -07002596 parport_init_mode= [HW,PPT]
2597 Configure VIA parallel port to operate in
2598 a specific mode. This is necessary on Pegasos
2599 computer where firmware has no options for setting
2600 up parallel port mode and sets it to spp.
2601 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002602 Format: [spp|ps2|epp|ecp|ecpepp]
2603
Andrew Mortondd287792006-03-23 03:00:57 -08002604 pause_on_oops=
2605 Halt all CPUs after the first oops has been printed for
2606 the specified number of seconds. This is to be used if
2607 your oopses keep scrolling off the screen.
2608
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 pcbit= [HW,ISDN]
2610
2611 pcd. [PARIDE]
2612 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002613 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002614
Randy Dunlapa9913042005-10-23 12:57:11 -07002615 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07002616 earlydump [X86] dump PCI config space before the kernel
2617 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02002618 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002619 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07002620 the hardware directly. Use this if your machine
2621 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002622 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07002623 hardware access methods are allowed. Use this
2624 if you experience crashes upon bootup and you
2625 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002626 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002627 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02002628 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002629 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07002630 noaer [PCIE] If the PCIEAER kernel config parameter is
2631 enabled, this kernel boot option can be used to
2632 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04002633 nodomains [PCI] Disable support for multiple PCI
2634 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302635 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08002636 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02002637 check_enable_amd_mmconf [X86] check for and enable
2638 properly configured MMIO access to PCI
2639 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07002640 nomsi [MSI] If the PCI_MSI kernel config parameter is
2641 enabled, this kernel boot option can be used to
2642 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02002643 noioapicquirk [APIC] Disable all boot interrupt quirks.
2644 Safety option to keep boot IRQs enabled. This
2645 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02002646 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2647 primary IO-APIC for bridges that cannot disable
2648 boot IRQs. This fixes a source of spurious IRQs
2649 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02002650 noioapicreroute [APIC] Disable workaround that uses the
2651 boot IRQ equivalent of an IRQ that connects to
2652 a chipset where boot IRQs cannot be disabled.
2653 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002654 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07002655 routing table. These calls are known to be buggy
2656 on several machines and they hang the machine
2657 when used, but on other computers it's the only
2658 way to get the interrupt routing table. Try
2659 this option if the kernel is unable to allocate
2660 IRQs or discover secondary PCI buses on your
2661 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02002662 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07002663 Use with caution as certain devices share
2664 address decoders between ROMs and other
2665 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02002666 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07002667 expansion ROMs that do not already have
2668 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07002669 nobar [X86] Do not assign address space to the
2670 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002671 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002672 assigned automatically to PCI devices. You can
2673 make the kernel exclude IRQs of your ISA cards
2674 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002675 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002676 of the PIRQ table (normally generated
2677 by the BIOS) if it is outside the
2678 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002679 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002680 useful if the kernel is unable to find your
2681 secondary buses and you want to tell it
2682 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002683 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002684 numbers ourselves, overriding
2685 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002686 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002687 in the BIOS $PIR table. This is needed on
2688 some systems with broken BIOSes, notably
2689 some HP Pavilion N5400 and Omnibook XE3
2690 notebooks. This will have no effect if ACPI
2691 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002692 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002693 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002694 use_crs [X86] Use PCI host bridge window information
2695 from ACPI. On BIOSes from 2008 or later, this
2696 is enabled by default. If you need to use this,
2697 please report a bug.
2698 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2699 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002700 routeirq Do IRQ routing for all PCI devices.
2701 This is normally done in pci_enable_device(),
2702 so this option is a temporary workaround
2703 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002704 skip_isa_align [X86] do not align io start addr, so can
2705 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002706 firmware [ARM] Do not re-enumerate the bus but instead
2707 just use the configuration from the
2708 bootloader. This is currently used on
2709 IXP2000 systems where the bus has to be
2710 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002711 noearly [X86] Don't do any early type 1 scanning.
2712 This might help on some broken boards which
2713 machine check when some devices' config space
2714 is read. But various workarounds are disabled
2715 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002716 bfsort Sort PCI devices into breadth-first order.
2717 This sorting is done to get a device
2718 order compatible with older (<= 2.4) kernels.
2719 nobfsort Don't sort PCI devices into breadth-first order.
Yijing Wangfa238712013-01-30 09:40:52 +08002720 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2721 tuning and use the BIOS-configured MPS defaults.
2722 pcie_bus_safe Set every device's MPS to the largest value
2723 supported by all devices below the root complex.
2724 pcie_bus_perf Set device MPS to the largest allowable MPS
2725 based on its parent bus. Also set MRRS (Max
2726 Read Request Size) to the largest supported
2727 value (no larger than the MPS that the device
2728 or bus can support) for best performance.
2729 pcie_bus_peer2peer Set every device's MPS to 128B, which
2730 every device is guaranteed to support. This
2731 configuration allows peer-to-peer DMA between
2732 any pair of devices, possibly at the cost of
2733 reduced performance. This also guarantees
2734 that hot-added devices will work.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002735 cbiosize=nn[KMG] The fixed amount of bus space which is
2736 reserved for the CardBus bridge's IO window.
2737 The default value is 256 bytes.
2738 cbmemsize=nn[KMG] The fixed amount of bus space which is
2739 reserved for the CardBus bridge's memory
2740 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002741 resource_alignment=
2742 Format:
2743 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2744 Specifies alignment and device to reassign
2745 aligned memory resources.
2746 If <order of align> is not specified,
2747 PAGE_SIZE is used as alignment.
2748 PCI-PCI bridge can be specified, if resource
2749 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002750 ecrc= Enable/disable PCIe ECRC (transaction layer
2751 end-to-end CRC checking).
2752 bios: Use BIOS/firmware settings. This is the
2753 the default.
2754 off: Turn ECRC off
2755 on: Turn ECRC on.
Yijing Wang8c8803c2013-01-23 20:29:06 +08002756 hpiosize=nn[KMG] The fixed amount of bus space which is
2757 reserved for hotplug bridge's IO window.
2758 Default size is 256 bytes.
2759 hpmemsize=nn[KMG] The fixed amount of bus space which is
2760 reserved for hotplug bridge's memory window.
2761 Default size is 2 megabytes.
Yinghai Lub55438f2012-02-23 19:23:30 -08002762 realloc= Enable/disable reallocating PCI bridge resources
2763 if allocations done by BIOS are too small to
2764 accommodate resources required by all child
2765 devices.
2766 off: Turn realloc off
2767 on: Turn realloc on
2768 realloc same as realloc=on
Rafael J. Wysocki6748dcc2012-03-01 00:06:33 +01002769 noari do not use PCIe ARI.
Bjorn Helgaas284f5f92012-04-30 15:21:02 -06002770 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2771 only look for one device below a PCIe downstream
2772 port.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002773
Chuck Ebberte5665a42008-09-24 20:40:34 -04002774 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2775 Management.
2776 off Disable ASPM.
2777 force Enable ASPM even on devices that claim not to support it.
2778 WARNING: Forcing ASPM on may cause system lockups.
2779
MUNEDA Takahiro7570a332012-02-02 11:09:22 -05002780 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2781 nomsi Do not use MSI for PCI Express Native Hotplug (this
2782 makes all PCIe ports use INTx for hotplug services).
2783
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002784 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002785 auto Ask the BIOS whether or not to use native PCIe services
2786 associated with PCIe ports (PME, hot-plug, AER). Use
2787 them only if that is allowed by the BIOS.
2788 native Use native PCIe services associated with PCIe ports
2789 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002790 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2791 ports driver.
2792
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002793 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002794 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002795 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002796
Linus Torvalds1da177e2005-04-16 15:20:36 -07002797 pcmv= [HW,PCMCIA] BadgePAD 4
2798
Tushar Behera39ac5ba2014-03-28 10:50:21 +05302799 pd_ignore_unused
2800 [PM]
2801 Keep all power-domains already enabled by bootloader on,
2802 even if no driver has claimed them. This is useful
2803 for debug and development, but should not be
2804 needed on a platform with proper driver support.
2805
Linus Torvalds1da177e2005-04-16 15:20:36 -07002806 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002807 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002808
2809 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2810 boot time.
2811 Format: { 0 | 1 }
2812 See arch/parisc/kernel/pdc_chassis.c
2813
Tejun Heof58dc012009-08-14 15:00:50 +09002814 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002815 Currently supported values are "embed" and "page".
2816 Archs may support subset or none of the selections.
2817 See comments in mm/percpu.c for details on each
2818 allocator. This parameter is primarily for debugging
2819 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002820
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002822 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823
2824 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002825 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826
2827 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002828 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002829
2830 plip= [PPT,NET] Parallel port network link
2831 Format: { parport<nr> | timid | 0 }
2832 See also Documentation/parport.txt.
2833
Randy Dunlap16290242011-08-13 12:34:52 -07002834 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002835 Override pmtimer IOPort with a hex value.
2836 e.g. pmtmr=0x508
2837
Bjorn Helgaas96242112011-08-11 12:14:05 -06002838 pnp.debug=1 [PNP]
2839 Enable PNP debug messages (depends on the
2840 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2841 via /sys/module/pnp/parameters/debug. We always show
2842 current resource usage; turning this on also shows
2843 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002844
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845 pnpacpi= [ACPI]
2846 { off }
2847
2848 pnpbios= [ISAPNP]
2849 { on | off | curr | res | no-curr | no-res }
2850
2851 pnp_reserve_irq=
2852 [ISAPNP] Exclude IRQs for the autoconfiguration
2853
2854 pnp_reserve_dma=
2855 [ISAPNP] Exclude DMAs for the autoconfiguration
2856
2857 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002858 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859
2860 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002861 [ISAPNP] Exclude memory regions for the
2862 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863 Ranges are in pairs (memory base and size).
2864
Randy Dunlap4af94f32009-04-17 18:30:28 -07002865 ports= [IP_VS_FTP] IPVS ftp helper module
2866 Default is 21.
2867 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2868 may be specified.
2869 Format: <port>,<port>....
2870
Ingo Molnar45807a12007-07-15 23:40:10 -07002871 print-fatal-signals=
2872 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002873
2874 If enabled, warn about various signal handling
2875 related application anomalies: too many signals,
2876 too many POSIX.1 timers, fatal signals causing a
2877 coredump - etc.
2878
2879 If you hit the warning due to signal overflow,
2880 you might want to try "ulimit -i unlimited".
2881
Ingo Molnar45807a12007-07-15 23:40:10 -07002882 default: off.
2883
Matthew Garrettc22ab332012-03-05 14:59:10 -08002884 printk.always_kmsg_dump=
2885 Trigger kmsg_dump for cases other than kernel oops or
2886 panics
2887 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2888 default: disabled
2889
Randy Dunlape84845c2007-07-15 23:40:25 -07002890 printk.time= Show timing data prefixed to each printk message line
2891 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2892
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002893 processor.max_cstate= [HW,ACPI]
2894 Limit processor to maximum C-state
2895 max_cstate=9 overrides any DMI blacklist limit.
2896
2897 processor.nocst [HW,ACPI]
2898 Ignore the _CST method to determine C-states,
2899 instead using the legacy FADT method
2900
Linus Torvalds1da177e2005-04-16 15:20:36 -07002901 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002902 Format: [schedule,]<number>
2903 Param: "schedule" - profile schedule points.
2904 Param: <number> - step/bucket size as a power of 2 for
2905 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002906 Param: "sleep" - profile D-state sleeping (millisecs).
2907 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002908 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002909
Linus Torvalds1da177e2005-04-16 15:20:36 -07002910 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2911 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002912 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002913
Randy Dunlapa9913042005-10-23 12:57:11 -07002914 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2915 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002916 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2917 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002918 psmouse.resetafter= [HW,MOUSE]
2919 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920 (0 = never).
2921 psmouse.resolution=
2922 [HW,MOUSE] Set desired mouse resolution, in dpi.
2923 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002924 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002925 0 = disabled, 1 = enabled (default).
2926
Matthew Garrettdee28e72011-07-21 16:57:55 -04002927 pstore.backend= Specify the name of the pstore backend to use
2928
Linus Torvalds1da177e2005-04-16 15:20:36 -07002929 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002930 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002931
Kay Sieversdc8c8582007-08-15 12:25:38 +02002932 pty.legacy_count=
2933 [KNL] Number of legacy pty's. Overwrites compiled-in
2934 default number.
2935
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002936 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002937
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938 r128= [HW,DRM]
2939
2940 raid= [HW,RAID]
2941 See Documentation/md.txt.
2942
Randy Dunlapa9913042005-10-23 12:57:11 -07002943 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002944 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002945
Linus Torvalds1da177e2005-04-16 15:20:36 -07002946 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002947 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002949 rcu_nocbs= [KNL]
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002950 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2951 the specified list of CPUs to be no-callback CPUs.
2952 Invocation of these CPUs' RCU callbacks will
Paul E. McKenneya4889852012-12-03 08:16:28 -08002953 be offloaded to "rcuox/N" kthreads created for
2954 that purpose, where "x" is "b" for RCU-bh, "p"
2955 for RCU-preempt, and "s" for RCU-sched, and "N"
2956 is the CPU number. This reduces OS jitter on the
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002957 offloaded CPUs, which can be useful for HPC and
2958 real-time workloads. It can also improve energy
2959 efficiency for asymmetric multiprocessors.
2960
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002961 rcu_nocb_poll [KNL]
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002962 Rather than requiring that offloaded CPUs
2963 (specified by rcu_nocbs= above) explicitly
2964 awaken the corresponding "rcuoN" kthreads,
2965 make these kthreads poll for callbacks.
2966 This improves the real-time response for the
2967 offloaded CPUs by relieving them of the need to
2968 wake up the corresponding kthread, but degrades
2969 energy efficiency by requiring that the kthreads
2970 periodically wake up to do the polling.
2971
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002972 rcutree.blimit= [KNL]
Paul E. McKenney97e63f02013-10-27 09:44:03 -07002973 Set maximum number of finished RCU callbacks to
2974 process in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002975
Paul E. McKenney37745d22015-01-22 18:24:08 -08002976 rcutree.gp_init_delay= [KNL]
2977 Set the number of jiffies to delay each step of
2978 RCU grace-period initialization. This only has
2979 effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT is
2980 set.
2981
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002982 rcutree.rcu_fanout_leaf= [KNL]
Paul E. McKenneyf885b7f2012-04-23 15:52:53 -07002983 Increase the number of CPUs assigned to each
2984 leaf rcu_node structure. Useful for very large
2985 systems.
2986
Paul E. McKenney4a81e832014-06-20 16:49:01 -07002987 rcutree.jiffies_till_sched_qs= [KNL]
2988 Set required age in jiffies for a
2989 given grace period before RCU starts
2990 soliciting quiescent-state help from
2991 rcu_note_context_switch().
2992
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002993 rcutree.jiffies_till_first_fqs= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08002994 Set delay from grace-period initialization to
2995 first attempt to force quiescent states.
2996 Units are jiffies, minimum value is zero,
2997 and maximum value is HZ.
2998
Paul E. McKenney4102ada2013-10-08 20:23:47 -07002999 rcutree.jiffies_till_next_fqs= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003000 Set delay between subsequent attempts to force
3001 quiescent states. Units are jiffies, minimum
3002 value is one, and maximum value is HZ.
3003
Clark Williams21871d72014-09-12 21:21:09 -05003004 rcutree.kthread_prio= [KNL,BOOT]
Paul E. McKenneyd2af1ad2015-01-20 23:54:59 -08003005 Set the SCHED_FIFO priority of the RCU per-CPU
3006 kthreads (rcuc/N). This value is also used for
3007 the priority of the RCU boost threads (rcub/N)
3008 and for the RCU grace-period kthreads (rcu_bh,
3009 rcu_preempt, and rcu_sched). If RCU_BOOST is
3010 set, valid values are 1-99 and the default is 1
3011 (the least-favored priority). Otherwise, when
3012 RCU_BOOST is not set, valid values are 0-99 and
3013 the default is zero (non-realtime operation).
Clark Williams21871d72014-09-12 21:21:09 -05003014
Paul E. McKenneyfbce7492014-06-24 09:26:11 -07003015 rcutree.rcu_nocb_leader_stride= [KNL]
3016 Set the number of NOCB kthread groups, which
3017 defaults to the square root of the number of
3018 CPUs. Larger numbers reduces the wakeup overhead
3019 on the per-CPU grace-period kthreads, but increases
3020 that same overhead on each group's leader.
3021
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003022 rcutree.qhimark= [KNL]
Paul E. McKenney97e63f02013-10-27 09:44:03 -07003023 Set threshold of queued RCU callbacks beyond which
3024 batch limiting is disabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08003025
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003026 rcutree.qlowmark= [KNL]
Robert P. J. Day24aaef82008-02-03 15:20:26 +02003027 Set threshold of queued RCU callbacks below which
3028 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08003029
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003030 rcutree.rcu_idle_gp_delay= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003031 Set wakeup interval for idle CPUs that have
3032 RCU callbacks (RCU_FAST_NO_HZ=y).
Paul E. McKenneyd40011f2012-06-26 20:45:57 -07003033
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003034 rcutree.rcu_idle_lazy_gp_delay= [KNL]
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -08003035 Set wakeup interval for idle CPUs that have
3036 only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
3037 Lazy RCU callbacks are those which RCU can
3038 prove do nothing more than free memory.
Paul E. McKenneyd40011f2012-06-26 20:45:57 -07003039
Paul E. McKenney38706bc2014-08-18 21:12:17 -07003040 rcutorture.cbflood_inter_holdoff= [KNL]
3041 Set holdoff time (jiffies) between successive
3042 callback-flood tests.
3043
3044 rcutorture.cbflood_intra_holdoff= [KNL]
3045 Set holdoff time (jiffies) between successive
3046 bursts of callbacks within a given callback-flood
3047 test.
3048
3049 rcutorture.cbflood_n_burst= [KNL]
3050 Set the number of bursts making up a given
3051 callback-flood test. Set this to zero to
3052 disable callback-flood testing.
3053
3054 rcutorture.cbflood_n_per_burst= [KNL]
3055 Set the number of callbacks to be registered
3056 in a given burst of a callback-flood test.
3057
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003058 rcutorture.fqs_duration= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003059 Set duration of force_quiescent_state bursts.
3060
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003061 rcutorture.fqs_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003062 Set holdoff time within force_quiescent_state bursts.
3063
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003064 rcutorture.fqs_stutter= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003065 Set wait time between force_quiescent_state bursts.
3066
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003067 rcutorture.gp_exp= [KNL]
3068 Use expedited update-side primitives.
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003069
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003070 rcutorture.gp_normal= [KNL]
3071 Use normal (non-expedited) update-side primitives.
3072 If both gp_exp and gp_normal are set, do both.
3073 If neither gp_exp nor gp_normal are set, still
3074 do both.
3075
3076 rcutorture.n_barrier_cbs= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003077 Set callbacks/threads for rcu_barrier() testing.
3078
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003079 rcutorture.nfakewriters= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003080 Set number of concurrent RCU writers. These just
3081 stress RCU, they don't participate in the actual
3082 test, hence the "fake".
3083
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003084 rcutorture.nreaders= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003085 Set number of RCU readers.
3086
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003087 rcutorture.object_debug= [KNL]
3088 Enable debug-object double-call_rcu() testing.
3089
3090 rcutorture.onoff_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003091 Set time (s) after boot for CPU-hotplug testing.
3092
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003093 rcutorture.onoff_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003094 Set time (s) between CPU-hotplug operations, or
3095 zero to disable CPU-hotplug testing.
3096
Paul E. McKenney59da22a2014-09-12 10:36:15 -07003097 rcutorture.torture_runnable= [BOOT]
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003098 Start rcutorture running at boot time.
3099
3100 rcutorture.shuffle_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003101 Set task-shuffle interval (s). Shuffling tasks
3102 allows some CPUs to go into dyntick-idle mode
3103 during the rcutorture test.
3104
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003105 rcutorture.shutdown_secs= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003106 Set time (s) after boot system shutdown. This
3107 is useful for hands-off automated testing.
3108
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003109 rcutorture.stall_cpu= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003110 Duration of CPU stall (s) to test RCU CPU stall
3111 warnings, zero to disable.
3112
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003113 rcutorture.stall_cpu_holdoff= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003114 Time to wait (s) after boot before inducing stall.
3115
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003116 rcutorture.stat_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003117 Time (s) between statistics printk()s.
3118
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003119 rcutorture.stutter= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003120 Time (s) to stutter testing, for example, specifying
3121 five seconds causes the test to run for five seconds,
3122 wait for five seconds, and so on. This tests RCU's
3123 ability to transition abruptly to and from idle.
3124
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003125 rcutorture.test_boost= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003126 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
3127 "Maybe" means test if the RCU implementation
3128 under test support RCU priority boosting.
3129
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003130 rcutorture.test_boost_duration= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003131 Duration (s) of each individual boost test.
3132
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003133 rcutorture.test_boost_interval= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003134 Interval (s) between each boost test.
3135
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003136 rcutorture.test_no_idle_hz= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003137 Test RCU's dyntick-idle handling. See also the
3138 rcutorture.shuffle_interval parameter.
3139
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003140 rcutorture.torture_type= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003141 Specify the RCU implementation to test.
3142
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003143 rcutorture.verbose= [KNL]
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07003144 Enable additional printk() statements.
3145
Paul E. McKenney4102ada2013-10-08 20:23:47 -07003146 rcupdate.rcu_expedited= [KNL]
3147 Use expedited grace-period primitives, for
3148 example, synchronize_rcu_expedited() instead
3149 of synchronize_rcu(). This reduces latency,
3150 but can increase CPU utilization, degrade
3151 real-time latency, and degrade energy efficiency.
3152
3153 rcupdate.rcu_cpu_stall_suppress= [KNL]
3154 Suppress RCU CPU stall warning messages.
3155
3156 rcupdate.rcu_cpu_stall_timeout= [KNL]
3157 Set timeout for RCU CPU stall warning messages.
3158
Paul E. McKenney52db30a2014-07-01 18:16:30 -07003159 rcupdate.rcu_task_stall_timeout= [KNL]
3160 Set timeout in jiffies for RCU task stall warning
3161 messages. Disable with a value less than or equal
3162 to zero.
3163
Pranith Kumar74860fe2014-09-19 11:34:09 -04003164 rcupdate.rcu_self_test= [KNL]
3165 Run the RCU early boot self tests
3166
3167 rcupdate.rcu_self_test_bh= [KNL]
3168 Run the RCU bh early boot self tests
3169
3170 rcupdate.rcu_self_test_sched= [KNL]
3171 Run the RCU sched early boot self tests
3172
Olof Johanssonffdfc402005-09-06 15:17:19 -07003173 rdinit= [KNL]
3174 Format: <full_path>
3175 Run specified binary instead of /init from the ramdisk,
3176 used for early userspace startup. See initrd.
3177
Robin Holt1b3a5d02013-07-08 16:01:42 -07003178 reboot= [KNL]
3179 Format (x86 or x86_64):
3180 [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
3181 [[,]s[mp]#### \
3182 [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
3183 [[,]f[orce]
3184 Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
3185 reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
3186 reboot_force is either force or not specified,
3187 reboot_cpu is s[mp]#### with #### being the processor
3188 to be used for rebooting.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003189
Paul Jackson46b6d942008-07-04 10:00:09 -07003190 relax_domain_level=
3191 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01003192 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07003193
Rafael J. Wysocki0399d4d2014-05-26 13:40:59 +02003194 relative_sleep_states=
3195 [SUSPEND] Use sleep state labeling where the deepest
3196 state available other than hibernation is always "mem".
3197 Format: { "0" | "1" }
3198 0 -- Traditional sleep state labels.
3199 1 -- Relative sleep state labels.
3200
Linus Torvalds1da177e2005-04-16 15:20:36 -07003201 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
3202
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003203 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07003204 Format: nn[KMG]
3205 Reserves a hole at the top of the kernel virtual
3206 address space.
3207
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07003208 reservelow= [X86]
3209 Format: nn[K]
3210 Set the amount of memory to reserve for BIOS at
3211 the bottom of the address space.
3212
Vivek Goyal7e962872006-09-27 01:50:44 -07003213 reset_devices [KNL] Force drivers to reset the underlying device
3214 during initialization.
3215
Randy Dunlapa9913042005-10-23 12:57:11 -07003216 resume= [SWSUSP]
3217 Specify the partition device for software suspend
Minho Ban2df83fa2012-05-14 21:45:31 +02003218 Format:
3219 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003220
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08003221 resume_offset= [SWSUSP]
3222 Specify the offset from the beginning of the partition
3223 given by "resume=" at which the swap header is located,
3224 in <PAGE_SIZE> units (needed only for swap files).
3225 See Documentation/power/swsusp-and-swap-files.txt
3226
Barry Songf126f732011-10-10 23:38:41 +02003227 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
3228 read the resume files
3229
Barry Song6f8d7022011-10-06 20:34:46 +02003230 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
3231 Useful for devices that are detected asynchronously
3232 (e.g. USB and MMC devices).
3233
Bojan Smojverf996fc92010-09-09 23:06:23 +02003234 hibernate= [HIBERNATION]
3235 noresume Don't check if there's a hibernation image
3236 present during boot.
3237 nocompress Don't compress/decompress hibernation images.
Kees Cooka6e15a32014-06-13 13:30:35 -07003238 no Disable hibernation and resume.
Bojan Smojverf996fc92010-09-09 23:06:23 +02003239
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08003240 retain_initrd [RAM] Keep initrd memory after extraction
3241
Andrew Clausen0efbb782015-01-09 20:24:55 +00003242 rfkill.default_state=
3243 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm,
3244 etc. communication is blocked by default.
3245 1 Unblocked.
3246
3247 rfkill.master_switch_mode=
3248 0 The "airplane mode" button does nothing.
3249 1 The "airplane mode" button toggles between everything
3250 blocked and the previous configuration.
3251 2 The "airplane mode" button toggles between everything
3252 blocked and everything unblocked.
3253
Linus Torvalds1da177e2005-04-16 15:20:36 -07003254 rhash_entries= [KNL,NET]
3255 Set number of hash buckets for route cache
3256
Linus Torvalds1da177e2005-04-16 15:20:36 -07003257 ro [KNL] Mount root device read-only on boot
3258
3259 root= [KNL] Root filesystem
Will Drewryf2d34fd2011-08-03 16:21:08 -07003260 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003261
3262 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
3263 mount the root filesystem
3264
3265 rootflags= [KNL] Set root filesystem mount option string
3266
3267 rootfstype= [KNL] Set root filesystem type
3268
Pierre Ossmancc1ed752007-07-15 23:40:35 -07003269 rootwait [KNL] Wait (indefinitely) for root device to show up.
3270 Useful for devices that are detected asynchronously
3271 (e.g. USB and MMC devices).
3272
Robert Tivy5c71d612013-03-28 18:41:46 -07003273 rproc_mem=nn[KMG][@address]
3274 [KNL,ARM,CMA] Remoteproc physical memory block.
3275 Memory area to be used by remote processor image,
3276 managed by CMA.
3277
Linus Torvalds1da177e2005-04-16 15:20:36 -07003278 rw [KNL] Mount root device read-write on boot
3279
3280 S [KNL] Run init in single mode
3281
Gerald Schaeferc60d1ae2014-07-18 17:37:08 +02003282 s390_iommu= [HW,S390]
3283 Set s390 IOTLB flushing mode
3284 strict
3285 With strict flushing every unmap operation will result in
3286 an IOTLB flush. Default is lazy flushing before reuse,
3287 which is faster.
3288
Linus Torvalds1da177e2005-04-16 15:20:36 -07003289 sa1100ir [NET]
3290 See drivers/net/irda/sa1100_ir.c.
3291
Linus Torvalds1da177e2005-04-16 15:20:36 -07003292 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07003293
Mike Travisf6630112009-11-17 18:22:15 -06003294 sched_debug [KNL] Enables verbose scheduler debug messages.
3295
Mike Galbraith5307c952012-05-08 12:20:58 +02003296 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
3297 xtime_lock contention on larger systems, and/or RCU lock
3298 contention on all systems with CONFIG_MAXSMP set.
3299 Format: { "0" | "1" }
3300 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
3301 1 -- enable.
3302 Note: increases power consumption, thus should only be
3303 enabled if running jitter sensitive (HPC/RT) workloads.
3304
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003305 security= [SECURITY] Choose a security module to enable at boot.
3306 If this boot parameter is not specified, only the first
3307 security module asking for security registration will be
3308 loaded. An invalid security module name will be treated
3309 as if no module has been chosen.
3310
3311 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003312 Format: { "0" | "1" }
3313 See security/selinux/Kconfig help text.
3314 0 -- disable.
3315 1 -- enable.
3316 Default value is set via kernel config option.
3317 If enabled at boot time, /selinux/disable can be used
3318 later to disable prior to initial policy load.
3319
John Johansenc1c124e2010-07-29 14:48:09 -07003320 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
3321 Format: { "0" | "1" }
3322 See security/apparmor/Kconfig help text
3323 0 -- disable.
3324 1 -- enable.
3325 Default value is set via kernel config option.
3326
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003327 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07003328
Linus Torvalds1da177e2005-04-16 15:20:36 -07003329 shapers= [NET]
3330 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07003331
Yinghai Lub05f78f2008-08-22 01:32:50 -07003332 show_msr= [x86] show boot-time MSR settings
3333 Format: { <integer> }
3334 Show boot-time (BIOS-initialized) MSR settings.
3335 The parameter means the number of CPUs to show,
3336 for example 1 means boot CPU only.
3337
Linus Torvalds1da177e2005-04-16 15:20:36 -07003338 simeth= [IA-64]
3339 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07003340
Linus Torvalds1da177e2005-04-16 15:20:36 -07003341 slram= [HW,MTD]
3342
Joonsoo Kim423c9292014-10-09 15:26:22 -07003343 slab_nomerge [MM]
3344 Disable merging of slabs with similar size. May be
3345 necessary if there is some reason to distinguish
3346 allocs to different slabs. Debug options disable
3347 merging on their own.
3348 For more information see Documentation/vm/slub.txt.
3349
David Rientjes3df1ccc2011-10-18 22:09:28 -07003350 slab_max_order= [MM, SLAB]
3351 Determines the maximum allowed order for slabs.
3352 A high setting may cause OOMs due to memory
3353 fragmentation. Defaults to 1 for systems with
3354 more than 32MB of RAM, 0 otherwise.
3355
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003356 slub_debug[=options[,slabs]] [MM, SLUB]
3357 Enabling slub_debug allows one to determine the
3358 culprit if slab objects become corrupted. Enabling
3359 slub_debug can create guard zones around objects and
3360 may poison objects when not in use. Also tracks the
3361 last alloc / free. For more information see
3362 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003363
3364 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003365 Determines the maximum allowed order for slabs.
3366 A high setting may cause OOMs due to memory
3367 fragmentation. For more information see
3368 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003369
3370 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003371 The minimum number of objects per slab. SLUB will
3372 increase the slab order up to slub_max_order to
3373 generate a sufficiently large slab able to contain
3374 the number of objects indicated. The higher the number
3375 of objects the smaller the overhead of tracking slabs
3376 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003377 For more information see Documentation/vm/slub.txt.
3378
3379 slub_min_order= [MM, SLUB]
Masanari Iida24775d62012-02-15 00:26:42 +09003380 Determines the minimum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07003381 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003382 For more information see Documentation/vm/slub.txt.
3383
3384 slub_nomerge [MM, SLUB]
Joonsoo Kim423c9292014-10-09 15:26:22 -07003385 Same with slab_nomerge. This is supported for legacy.
3386 See slab_nomerge for more information.
Christoph Lameterc1aee212007-05-31 00:40:47 -07003387
Linus Torvalds1da177e2005-04-16 15:20:36 -07003388 smart2= [HW]
3389 Format: <io1>[,<io2>[,...,<io8>]]
3390
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07003391 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
3392 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
3393 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
3394 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
3395 smsc-ircc2.ircc_irq= [HW] IRQ line
3396 smsc-ircc2.ircc_dma= [HW] DMA channel
3397 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3398 0: Toshiba Satellite 1800 (GP data pin select)
3399 1: Fast pin select (default)
3400 2: ATC IRMode
3401
Ingo Molnar9c44bc02008-05-12 21:21:04 +02003402 softlockup_panic=
3403 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07003404 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02003405
Aaron Tomlined235872014-06-23 13:22:05 -07003406 softlockup_all_cpu_backtrace=
3407 [KNL] Should the soft-lockup detector generate
3408 backtraces on all cpus.
3409 Format: <integer>
3410
Linus Torvalds1da177e2005-04-16 15:20:36 -07003411 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02003412 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07003413
Linus Torvalds1da177e2005-04-16 15:20:36 -07003414 spia_io_base= [HW,MTD]
3415 spia_fio_base=
3416 spia_pedr=
3417 spia_peddr=
3418
Steven Rostedtf38f1d22008-12-16 23:06:40 -05003419 stacktrace [FTRACE]
3420 Enabled the stack tracer on boot up.
3421
Steven Rostedt762e1202011-12-19 22:01:00 -05003422 stacktrace_filter=[function-list]
3423 [FTRACE] Limit the functions that the stack tracer
3424 will trace at boot up. function-list is a comma separated
3425 list of functions. This list can be changed at run
3426 time by the stack_trace_filter file in the debugfs
3427 tracing directory. Note, this enables stack tracing
3428 and the stacktrace above is not needed.
3429
Linus Torvalds1da177e2005-04-16 15:20:36 -07003430 sti= [PARISC,HW]
3431 Format: <num>
3432 Set the STI (builtin display/keyboard on the HP-PARISC
3433 machines) console (graphic card) which should be used
3434 as the initial boot-console.
3435 See also comment in drivers/video/console/sticore.c.
3436
3437 sti_font= [HW]
3438 See comment in drivers/video/console/sticore.c.
3439
3440 stifb= [HW]
3441 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3442
Trond Myklebustcbf11072009-08-09 15:06:19 -04003443 sunrpc.min_resvport=
3444 sunrpc.max_resvport=
3445 [NFS,SUNRPC]
3446 SunRPC servers often require that client requests
3447 originate from a privileged port (i.e. a port in the
3448 range 0 < portnr < 1024).
3449 An administrator who wishes to reserve some of these
3450 ports for other uses may adjust the range that the
3451 kernel's sunrpc client considers to be privileged
3452 using these two parameters to set the minimum and
3453 maximum port values.
3454
Greg Banks42a7fc42007-03-06 01:42:23 -08003455 sunrpc.pool_mode=
3456 [NFS]
3457 Control how the NFS server code allocates CPUs to
3458 service thread pools. Depending on how many NICs
3459 you have and where their interrupts are bound, this
3460 option will affect which CPUs will do NFS serving.
3461 Note: this parameter cannot be changed while the
3462 NFS server is running.
3463
3464 auto the server chooses an appropriate mode
3465 automatically using heuristics
3466 global a single global pool contains all CPUs
3467 percpu one pool for each CPU
3468 pernode one pool for each NUMA node (equivalent
3469 to global on non-NUMA machines)
3470
Trond Myklebustcbf11072009-08-09 15:06:19 -04003471 sunrpc.tcp_slot_table_entries=
3472 sunrpc.udp_slot_table_entries=
3473 [NFS,SUNRPC]
3474 Sets the upper limit on the number of simultaneous
3475 RPC calls that can be sent from the client to a
3476 server. Increasing these values may allow you to
3477 improve throughput, but will also increase the
3478 amount of memory reserved for use by the client.
3479
Brian Norris1d4a9c12015-02-22 21:16:49 -08003480 suspend.pm_test_delay=
3481 [SUSPEND]
3482 Sets the number of seconds to remain in a suspend test
3483 mode before resuming the system (see
3484 /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
3485 is set. Default value is 5.
3486
Michal Hocko07555ac2013-08-22 16:35:46 -07003487 swapaccount=[0|1]
Michal Hockoa42c3902010-11-24 12:57:08 -08003488 [KNL] Enable accounting of swap in memory resource
3489 controller if no parameter or 1 is given or disable
3490 it if 0 is given (See Documentation/cgroups/memory.txt)
3491
Jiri Kosina91fec0f2013-11-27 13:48:09 +01003492 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
3493 Format: { <int> | force }
3494 <int> -- Number of I/O TLB slabs
3495 force -- force using of bounce buffers even if they
3496 wouldn't be automatically used by the kernel
Randy Dunlapa9913042005-10-23 12:57:11 -07003497
Linus Torvalds1da177e2005-04-16 15:20:36 -07003498 switches= [HW,M68k]
3499
Andi Kleene52eec12010-09-08 16:54:17 +02003500 sysfs.deprecated=0|1 [KNL]
3501 Enable/disable old style sysfs layout for old udev
3502 on older distributions. When this option is enabled
3503 very new udev will not work anymore. When this option
3504 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3505 in older udev will not work anymore.
3506 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3507 the kernel configuration.
3508
Ingo Molnar5d6f6472006-12-13 00:34:36 -08003509 sysrq_always_enabled
3510 [KNL]
3511 Ignore sysrq setting - this boot parameter will
3512 neutralize any effect of /proc/sys/kernel/sysrq.
3513 Useful for debugging.
3514
Fabian Frederick747029a2014-11-06 19:46:50 +01003515 tcpmhash_entries= [KNL,NET]
3516 Set the number of tcp_metrics_hash slots.
3517 Default value is 8192 or 16384 depending on total
3518 ram pages. This is used to specify the TCP metrics
3519 cache size. See Documentation/networking/ip-sysctl.txt
3520 "tcp_no_metrics_save" section for more details.
3521
Linus Torvalds1da177e2005-04-16 15:20:36 -07003522 tdfx= [HW,DRM]
3523
Srinivas Pandruvadaacc82342014-09-02 11:54:41 -07003524 test_suspend= [SUSPEND][,N]
David Brownell77437fd2008-07-23 21:28:33 -07003525 Specify "mem" (for Suspend-to-RAM) or "standby" (for
Srinivas Pandruvadaacc82342014-09-02 11:54:41 -07003526 standby suspend) or "freeze" (for suspend type freeze)
3527 as the system sleep state during system startup with
3528 the optional capability to repeat N number of times.
3529 The system is woken from this state using a
3530 wakeup-capable RTC alarm.
David Brownell77437fd2008-07-23 21:28:33 -07003531
Linus Torvalds1da177e2005-04-16 15:20:36 -07003532 thash_entries= [KNL,NET]
3533 Set number of hash buckets for TCP connection
3534
Len Brownf8707ec2007-08-12 00:12:54 -04003535 thermal.act= [HW,ACPI]
3536 -1: disable all active trip points in all thermal zones
3537 <degrees C>: override all lowest active trip points
3538
Len Brownc52a7412007-08-14 15:49:32 -04003539 thermal.crt= [HW,ACPI]
3540 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04003541 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04003542
Len Brownf5487142007-08-12 00:12:44 -04003543 thermal.nocrt= [HW,ACPI]
3544 Set to disable actions on ACPI thermal zone
3545 critical and hot trip points.
3546
Len Brown72b33ef2007-08-12 00:12:17 -04003547 thermal.off= [HW,ACPI]
3548 1: disable ACPI thermal control
3549
Len Browna70cdc52007-08-12 00:12:35 -04003550 thermal.psv= [HW,ACPI]
3551 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08003552 <degrees C>: override all passive trip points to this
3553 value
Len Browna70cdc52007-08-12 00:12:35 -04003554
Len Brown730ff342007-08-12 00:12:26 -04003555 thermal.tzp= [HW,ACPI]
3556 Specify global default ACPI thermal zone polling rate
3557 <deci-seconds>: poll all this frequency
3558 0: no polling (default)
3559
Thomas Gleixner8d32a302011-02-23 23:52:23 +00003560 threadirqs [KNL]
3561 Force threading of all interrupt handlers except those
Masanari Iida24775d62012-02-15 00:26:42 +09003562 marked explicitly IRQF_NO_THREAD.
Thomas Gleixner8d32a302011-02-23 23:52:23 +00003563
Konrad Rzeszutek Wilk2ca62b02013-05-08 17:12:44 -04003564 tmem [KNL,XEN]
3565 Enable the Transcendent memory driver if built-in.
3566
3567 tmem.cleancache=0|1 [KNL, XEN]
3568 Default is on (1). Disable the usage of the cleancache
3569 API to send anonymous pages to the hypervisor.
3570
3571 tmem.frontswap=0|1 [KNL, XEN]
3572 Default is on (1). Disable the usage of the frontswap
Konrad Rzeszutek Wilk37d46e12013-05-14 13:56:42 -04003573 API to send swap pages to the hypervisor. If disabled
3574 the selfballooning and selfshrinking are force disabled.
Konrad Rzeszutek Wilk2ca62b02013-05-08 17:12:44 -04003575
3576 tmem.selfballooning=0|1 [KNL, XEN]
3577 Default is on (1). Disable the driving of swap pages
3578 to the hypervisor.
3579
3580 tmem.selfshrinking=0|1 [KNL, XEN]
3581 Default is on (1). Partial swapoff that immediately
3582 transfers pages from Xen hypervisor back to the
3583 kernel based on different criteria.
3584
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003585 topology= [S390]
3586 Format: {off | on}
3587 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07003588 topology information if the hardware supports this.
3589 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003590 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02003591 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01003592
Nishanth Aravamudan2d73bae2014-10-10 09:04:49 -07003593 topology_updates= [KNL, PPC, NUMA]
3594 Format: {off}
3595 Specify if the kernel should ignore (off)
3596 topology updates sent by the hypervisor to this
3597 LPAR.
3598
Linus Torvalds1da177e2005-04-16 15:20:36 -07003599 tp720= [HW,PS2]
3600
Rajiv Andrade225a9be2010-03-25 00:55:32 -03003601 tpm_suspend_pcr=[HW,TPM]
3602 Format: integer pcr id
3603 Specify that at suspend time, the tpm driver
3604 should extend the specified pcr with zeros,
3605 as a workaround for some chips which fail to
3606 flush the last written pcr on TPM_SaveState.
3607 This will guarantee that all the other pcrs
3608 are saved.
3609
Li Zefan9d612be2009-06-24 17:33:15 +08003610 trace_buf_size=nn[KMG]
Joonsoo Kim3e6fb8e2014-12-03 10:39:20 +09003611 [FTRACE] will set tracing buffer size on each cpu.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09003612
Li Zefan020e5f82009-07-01 10:47:05 +08003613 trace_event=[event-list]
3614 [FTRACE] Set and start specified trace events in order
3615 to facilitate early boot debugging.
3616 See also Documentation/trace/events.txt
3617
Steven Rostedt7bcfaf52012-11-01 22:56:07 -04003618 trace_options=[option-list]
3619 [FTRACE] Enable or disable tracer options at boot.
3620 The option-list is a comma delimited list of options
3621 that can be enabled or disabled just as if you were
3622 to echo the option name into
3623
3624 /sys/kernel/debug/tracing/trace_options
3625
3626 For example, to enable stacktrace option (to dump the
3627 stack trace of each event), add to the command line:
3628
3629 trace_options=stacktrace
3630
3631 See also Documentation/trace/ftrace.txt "trace options"
3632 section.
3633
Steven Rostedt (Red Hat)0daa23022014-12-12 22:27:10 -05003634 tp_printk[FTRACE]
3635 Have the tracepoints sent to printk as well as the
3636 tracing ring buffer. This is useful for early boot up
3637 where the system hangs or reboots and does not give the
3638 option for reading the tracing buffer or performing a
3639 ftrace_dump_on_oops.
3640
3641 To turn off having tracepoints sent to printk,
3642 echo 0 > /proc/sys/kernel/tracepoint_printk
3643 Note, echoing 1 into this file without the
3644 tracepoint_printk kernel cmdline option has no effect.
3645
3646 ** CAUTION **
3647
3648 Having tracepoints sent to printk() and activating high
3649 frequency tracepoints such as irq or sched, can cause
3650 the system to live lock.
3651
Steven Rostedt (Red Hat)de7edd32013-06-14 16:21:43 -04003652 traceoff_on_warning
3653 [FTRACE] enable this option to disable tracing when a
3654 warning is hit. This turns off "tracing_on". Tracing can
3655 be enabled again by echoing '1' into the "tracing_on"
3656 file located in /sys/kernel/debug/tracing/
3657
3658 This option is useful, as it disables the trace before
3659 the WARNING dump is called, which prevents the trace to
3660 be filled with content caused by the warning output.
3661
3662 This option can also be set at run time via the sysctl
3663 option: kernel/traceoff_on_warning
3664
Jiri Kosinafcf4d822012-03-21 16:34:02 -07003665 transparent_hugepage=
3666 [KNL]
3667 Format: [always|madvise|never]
3668 Can be used to control the default behavior of the system
3669 with respect to transparent hugepages.
3670 See Documentation/vm/transhuge.txt for more details.
3671
john stultzd3b8f882009-08-17 16:40:47 -07003672 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07003673 Format: <string>
3674 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07003675 disables clocksource verification at runtime, as well
3676 as the stability checks done at bootup. Used to enable
3677 high-resolution timer mode on older hardware, and in
3678 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07003679 [x86] noirqtime: Do not use TSC to do irq accounting.
3680 Used to run time disable IRQ_TIME_ACCOUNTING on any
3681 platforms where RDTSC is slow and this accounting
3682 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07003683
Randy Dunlapa9913042005-10-23 12:57:11 -07003684 turbografx.map[2|3]= [HW,JOY]
3685 TurboGraFX parallel port interface
3686 Format:
3687 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07003688 See also Documentation/input/joystick-parport.txt
3689
Christian Kujaub6935f82011-05-31 15:22:05 +00003690 udbg-immortal [PPC] When debugging early kernel crashes that
3691 happen after console_init() and before a proper
3692 console driver takes over, this boot options might
3693 help "seeing" what's going on.
3694
Eric Dumazetf86dcc52009-10-07 00:37:59 +00003695 uhash_entries= [KNL,NET]
3696 Set number of hash buckets for UDP/UDP-Lite connections
3697
Alan Stern5f8364b2006-12-05 16:29:55 -05003698 uhci-hcd.ignore_oc=
3699 [USB] Ignore overcurrent events (default N).
3700 Some badly-designed motherboards generate lots of
3701 bogus events, for ports that aren't wired to
3702 anything. Set this parameter to avoid log spamming.
3703 Note that genuine overcurrent events won't be
3704 reported either.
3705
Simon Arlotte3a61b02008-07-19 23:32:54 +01003706 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07003707 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01003708
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02003709 usbcore.authorized_default=
3710 [USB] Default USB device authorization:
3711 (default -1 = authorized except for wireless USB,
3712 0 = not authorized, 1 = authorized)
3713
Alan Sternb5e795f2007-02-20 15:00:53 -05003714 usbcore.autosuspend=
3715 [USB] The autosuspend time delay (in seconds) used
3716 for newly-detected USB devices (default 2). This
3717 is the time required before an idle device will be
3718 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04003719 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05003720
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003721 usbcore.usbfs_snoop=
3722 [USB] Set to log all usbfs traffic (default 0 = off).
3723
3724 usbcore.blinkenlights=
3725 [USB] Set to cycle leds on hubs (default 0 = off).
3726
3727 usbcore.old_scheme_first=
3728 [USB] Start with the old device initialization
3729 scheme (default 0 = off).
3730
Alan Stern3f5eb8d2011-11-17 16:41:35 -05003731 usbcore.usbfs_memory_mb=
3732 [USB] Memory limit (in MB) for buffers allocated by
3733 usbfs (default = 16, 0 = max = 2047).
3734
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003735 usbcore.use_both_schemes=
3736 [USB] Try the other device initialization scheme
3737 if the first one fails (default 1 = enabled).
3738
3739 usbcore.initial_descriptor_timeout=
3740 [USB] Specifies timeout for the initial 64-byte
3741 USB_REQ_GET_DESCRIPTOR request in milliseconds
3742 (default 5000 = 5.0 seconds).
3743
Linus Torvalds1da177e2005-04-16 15:20:36 -07003744 usbhid.mousepoll=
3745 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07003746
Alan Sternd4f373e2008-11-10 14:07:45 -05003747 usb-storage.delay_use=
3748 [UMS] The delay in seconds before a new device is
Mark Knibbs19101952014-11-04 13:00:15 +00003749 scanned for Logical Units (default 1).
Alan Sternd4f373e2008-11-10 14:07:45 -05003750
3751 usb-storage.quirks=
3752 [UMS] A list of quirks entries to supplement or
3753 override the built-in unusual_devs list. List
3754 entries are separated by commas. Each entry has
3755 the form VID:PID:Flags where VID and PID are Vendor
3756 and Product ID values (4-digit hex numbers) and
3757 Flags is a set of characters, each corresponding
3758 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05003759 a = SANE_SENSE (collect more than 18 bytes
3760 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05003761 b = BAD_SENSE (don't collect more than 18
3762 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05003763 c = FIX_CAPACITY (decrease the reported
3764 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01003765 d = NO_READ_DISC_INFO (don't use
3766 READ_DISC_INFO command);
3767 e = NO_READ_CAPACITY_16 (don't use
3768 READ_CAPACITY_16 command);
Hans de Goede734016b2014-09-16 18:36:52 +02003769 f = NO_REPORT_OPCODES (don't use report opcodes
3770 command, uas only);
Alan Sternc838ea42008-12-15 10:40:06 -05003771 h = CAPACITY_HEURISTICS (decrease the
3772 reported device capacity by one
3773 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05003774 i = IGNORE_DEVICE (don't bind to this
3775 device);
3776 l = NOT_LOCKABLE (don't try to lock and
3777 unlock ejectable media);
3778 m = MAX_SECTORS_64 (don't transfer more
3779 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04003780 n = INITIAL_READ10 (force a retry of the
3781 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05003782 o = CAPACITY_OK (accept the capacity
3783 reported by the device);
Namjae Jeoneaa05df2012-07-07 23:05:28 -04003784 p = WRITE_CACHE (the device cache is ON
3785 by default);
Alan Sternd4f373e2008-11-10 14:07:45 -05003786 r = IGNORE_RESIDUE (the device reports
3787 bogus residue values);
3788 s = SINGLE_LUN (the device has only one
3789 Logical Unit);
Hans de Goede59307852014-09-15 16:04:12 +02003790 t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
3791 commands, uas only);
Alan Sternb6089f12014-09-02 15:42:18 -04003792 u = IGNORE_UAS (don't bind to the uas driver);
Alan Sternd4f373e2008-11-10 14:07:45 -05003793 w = NO_WP_DETECT (don't test whether the
3794 medium is write-protected).
3795 Example: quirks=0419:aaf5:rl,0421:0433:rc
3796
Stephen Boydac1667d2011-08-13 12:34:50 -07003797 user_debug= [KNL,ARM]
3798 Format: <int>
3799 See arch/arm/Kconfig.debug help text.
3800 1 - undefined instruction events
3801 2 - system calls
3802 4 - invalid data aborts
3803 8 - SIGSEGV faults
3804 16 - SIGBUS faults
3805 Example: user_debug=31
3806
Ian Campbell14315592010-02-17 10:38:10 +00003807 userpte=
3808 [X86] Flags controlling user PTE allocations.
3809
3810 nohigh = do not allocate PTE pages in
3811 HIGHMEM regardless of setting
3812 of CONFIG_HIGHPTE.
3813
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05303814 vdso= [X86,SH]
Andy Lutomirskib0b49f22014-03-13 16:01:26 -07003815 On X86_32, this is an alias for vdso32=. Otherwise:
3816
3817 vdso=1: enable VDSO (the default)
Ingo Molnare6e54942006-06-27 02:53:50 -07003818 vdso=0: disable VDSO mapping
3819
Andy Lutomirskib0b49f22014-03-13 16:01:26 -07003820 vdso32= [X86] Control the 32-bit vDSO
3821 vdso32=1: enable 32-bit VDSO
3822 vdso32=0 or vdso32=2: disable 32-bit VDSO
3823
3824 See the help text for CONFIG_COMPAT_VDSO for more
3825 details. If CONFIG_COMPAT_VDSO is set, the default is
3826 vdso32=0; otherwise, the default is vdso32=1.
3827
3828 For compatibility with older kernels, vdso32=2 is an
3829 alias for vdso32=0.
3830
3831 Try vdso32=0 if you encounter an error that says:
3832 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
Roland McGrathaf65d642008-01-30 13:30:43 +01003833
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09003834 vector= [IA-64,SMP]
3835 vector=percpu: enable percpu vector domain
3836
Linus Torvalds1da177e2005-04-16 15:20:36 -07003837 video= [FB] Frame buffer configuration
3838 See Documentation/fb/modedb.txt.
3839
Aaron Lu3afe6da2013-06-20 15:08:55 +08003840 video.brightness_switch_enabled= [0,1]
3841 If set to 1, on receiving an ACPI notify event
3842 generated by hotkey, video driver will adjust brightness
3843 level and then send out the event to user space through
3844 the allocated input device; If set to 0, video driver
3845 will only send out the event without touching backlight
3846 brightness level.
Rafael J. Wysocki28437682014-07-14 19:35:45 +02003847 default: 1
Aaron Lu3afe6da2013-06-20 15:08:55 +08003848
Pawel Moll81a054c2012-05-09 18:30:16 +01003849 virtio_mmio.device=
3850 [VMMIO] Memory mapped virtio (platform) device.
3851
3852 <size>@<baseaddr>:<irq>[:<id>]
3853 where:
3854 <size> := size (can use standard suffixes
3855 like K, M and G)
3856 <baseaddr> := physical base address
3857 <irq> := interrupt number (as passed to
3858 request_irq())
3859 <id> := (optional) platform device id
3860 example:
3861 virtio_mmio.device=1K@0x100b0000:48:7
3862
3863 Can be used multiple times for multiple devices.
3864
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003865 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05003866 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07003867 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003868 Use vga=ask for menu.
3869 This is actually a boot loader parameter; the value is
3870 passed to the kernel using a special protocol.
3871
Randy Dunlapa9913042005-10-23 12:57:11 -07003872 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07003873 size of <nn>. This can be used to increase the
3874 minimum size (128MB on x86). It can also be used to
3875 decrease the size and leave more room for directly
3876 mapped kernel RAM.
3877
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003878 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3879 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07003880
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003881 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3882 Format: <command>
3883
3884 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3885 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07003886
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003887 vsyscall= [X86-64]
3888 Controls the behavior of vsyscalls (i.e. calls to
3889 fixed addresses of 0xffffffffff600x00 from legacy
3890 code). Most statically-linked binaries and older
3891 versions of glibc use these calls. Because these
3892 functions are at fixed addresses, they make nice
3893 targets for exploits that can control RIP.
3894
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003895 emulate [default] Vsyscalls turn into traps and are
3896 emulated reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003897
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003898 native Vsyscalls are native syscall instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003899 This is a little bit faster than trapping
3900 and makes a few dynamic recompilers work
3901 better than they would in emulation mode.
3902 It also makes exploits much easier to write.
3903
3904 none Vsyscalls don't work at all. This makes
3905 them quite hard to use for exploits but
3906 might break your system.
3907
Clemens Ladisch3855ae12013-08-04 13:09:50 +02003908 vt.color= [VT] Default text color.
3909 Format: 0xYX, X = foreground, Y = background.
3910 Default: 0x07 = light gray on black.
3911
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08003912 vt.cur_default= [VT] Default cursor shape.
3913 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3914 the parameters of the <Esc>[?A;B;Cc escape sequence;
3915 see VGA-softcursor.txt. Default: 2 = underline.
3916
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003917 vt.default_blu= [VT]
3918 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3919 Change the default blue palette of the console.
3920 This is a 16-member array composed of values
3921 ranging from 0-255.
3922
3923 vt.default_grn= [VT]
3924 Format: <green0>,<green1>,<green2>,...,<green15>
3925 Change the default green palette of the console.
3926 This is a 16-member array composed of values
3927 ranging from 0-255.
3928
3929 vt.default_red= [VT]
3930 Format: <red0>,<red1>,<red2>,...,<red15>
3931 Change the default red palette of the console.
3932 This is a 16-member array composed of values
3933 ranging from 0-255.
3934
3935 vt.default_utf8=
3936 [VT]
3937 Format=<0|1>
3938 Set system-wide default UTF-8 mode for all tty's.
3939 Default is 1, i.e. UTF-8 mode is enabled for all
3940 newly opened terminals.
3941
Matthew Garrettf6c06b62009-11-13 15:14:11 -05003942 vt.global_cursor_default=
3943 [VT]
3944 Format=<-1|0|1>
3945 Set system-wide default for whether a cursor
3946 is shown on new VTs. Default is -1,
3947 i.e. cursors will be created by default unless
3948 overridden by individual drivers. 0 will hide
3949 cursors, 1 will display them.
3950
Clemens Ladisch3855ae12013-08-04 13:09:50 +02003951 vt.italic= [VT] Default color for italic text; 0-15.
3952 Default: 2 = green.
3953
3954 vt.underline= [VT] Default color for underlined text; 0-15.
3955 Default: 3 = cyan.
3956
Randy Dunlap4724ba572010-05-03 11:42:52 -07003957 watchdog timers [HW,WDT] For information on watchdog timers,
3958 see Documentation/watchdog/watchdog-parameters.txt
3959 or other driver-specific files in the
3960 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003961
Tejun Heod55262c2013-04-01 11:23:38 -07003962 workqueue.disable_numa
3963 By default, all work items queued to unbound
3964 workqueues are affine to the NUMA nodes they're
3965 issued on, which results in better behavior in
3966 general. If NUMA affinity needs to be disabled for
3967 whatever reason, this option can be used. Note
3968 that this also can be controlled per-workqueue for
3969 workqueues visible under /sys/bus/workqueue/.
3970
Viresh Kumarcee22a12013-04-08 16:45:40 +05303971 workqueue.power_efficient
3972 Per-cpu workqueues are generally preferred because
3973 they show better performance thanks to cache
3974 locality; unfortunately, per-cpu workqueues tend to
3975 be more power hungry than unbound workqueues.
3976
3977 Enabling this makes the per-cpu workqueues which
3978 were observed to contribute significantly to power
3979 consumption unbound, leading to measurably lower
3980 power usage at the cost of small performance
3981 overhead.
3982
3983 The default value of this parameter is determined by
3984 the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
3985
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003986 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3987 default x2apic cluster mode on platforms
3988 supporting x2apic.
3989
Kuppuswamy Sathyanarayanan712b6aa2013-10-17 15:35:29 -07003990 x86_intel_mid_timer= [X86-32,APBT]
3991 Choose timer option for x86 Intel MID platform.
Jacob Panbb24c472009-09-02 07:37:17 -07003992 Two valid options are apbt timer only and lapic timer
3993 plus one apbt timer for broadcast timer.
Kuppuswamy Sathyanarayanan712b6aa2013-10-17 15:35:29 -07003994 x86_intel_mid_timer=apbt_only | lapic_and_apbt
Jacob Panbb24c472009-09-02 07:37:17 -07003995
Stefano Stabellinic1c54132010-05-14 12:44:30 +01003996 xen_emul_unplug= [HW,X86,XEN]
3997 Unplug Xen emulated devices
3998 Format: [unplug0,][unplug1]
3999 ide-disks -- unplug primary master IDE devices
4000 aux-ide-disks -- unplug non-primary-master IDE devices
4001 nics -- unplug network devices
4002 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01004003 unnecessary -- unplugging emulated devices is
4004 unnecessary even if the host did not respond to
4005 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01004006 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01004007
Konrad Rzeszutek Wilk15a3eac2013-09-25 10:07:20 -04004008 xen_nopvspin [X86,XEN]
4009 Disables the ticketlock slowpath using Xen PV
4010 optimizations.
4011
Konrad Rzeszutek Wilk8d693b92014-07-11 11:51:35 -04004012 xen_nopv [X86]
4013 Disables the PV optimizations forcing the HVM guest to
4014 run as generic HVM guest with no PV drivers.
4015
Linus Torvalds1da177e2005-04-16 15:20:36 -07004016 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07004017 Format:
4018 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07004019
Randy Dunlapa9913042005-10-23 12:57:11 -07004020______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07004021
4022TODO:
4023
Linus Torvalds1da177e2005-04-16 15:20:36 -07004024 Add more DRM drivers.