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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070043 ARM ARM architecture is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020044 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080046 BLACKFIN Blackfin architecture is enabled.
Alan Cox9cfe2682011-01-25 14:18:38 +000047 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
Mimi Zohar7102ebc2011-05-12 18:33:20 -040052 EVM Extended Verification Module
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 FB The frame buffer device is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070054 FTRACE Function tracing enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070055 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050058 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070060 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Brian Haleyb0f83b22010-02-04 13:36:50 -080061 IPV6 IPv6 support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
Jason Wessel84c08fd2010-05-20 21:04:24 -050065 KGDB Kernel debugger support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020066 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070067 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070075 MIPS MIPS architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070077 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070078 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070083 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070087 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
Randy Dunlap163475f2010-08-14 12:36:14 -070096 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
James Morris20510f22007-10-16 23:31:32 -070098 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 SELINUX SELinux support is enabled.
John Johansenc1c124e2010-07-29 14:48:09 -0700100 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +0900102 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300107 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500109 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700117 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700120 Documentation/x86/x86_64/boot-options.txt .
Randy Dunlap16290242011-08-13 12:34:52 -0700121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
Stefano Stabellinic1c54132010-05-14 12:44:30 +0100122 XEN Xen support is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
124In addition, the following text indicates that the option:
125
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
129
130Parameters denoted with BOOT are actually interpreted by the boot
131loader, and have no meaning to the kernel directly.
132Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500133need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
Karsten Weiss55588702007-02-13 13:26:21 +0100135There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700136See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100137
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139a trailing = on the name of any parameter states that that parameter will
140be entered as an environment variable, whereas its absence indicates that
141it will appear as a kernel argument readable via /proc/cmdline by programs
142running once the system is up.
143
jens m. noedler9c4751f2006-09-29 02:00:27 -0700144The number of kernel parameters is not limited, but the length of the
145complete command line (parameters including spaces etc.) is limited to
146a fixed number of characters. This limit depends on the architecture
147and is between 256 and 4096 characters. It is defined in the file
148./include/asm/setup.h as COMMAND_LINE_SIZE.
149
Ahmed S. Darwish7a19a232011-02-20 20:08:35 -0800150Finally, the [KMG] suffix is commonly described after a number of kernel
151parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153bytes respectively. Such letter suffixes can also be entirely omitted.
154
jens m. noedler9c4751f2006-09-29 02:00:27 -0700155
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530156 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800157 Advanced Configuration and Power Interface
Len Brown68ca4062010-02-19 00:09:22 -0500158 Format: { force | off | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -0700162 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800164 rsdt -- prefer RSDT over (default) XSDT
Lin Mingaa2110c2010-04-08 14:34:27 +0800165 copy_dsdt -- copy DSDT to memory
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Paul Bolle395cf962011-08-15 02:02:26 +0200167 See also Documentation/power/runtime_pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
Takao Indoh4996c022011-07-14 18:05:21 -0400169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
173
Len Browna1fdcc02007-03-11 03:26:14 -0400174 acpi_apic_instance= [ACPI, IOAPIC]
175 Format: <int>
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400178 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400179
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
182 acpi_backlight=video
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
186
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200210
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800214
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
217 default in APIC mode
218
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
221 default in PIC mode
222
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
225
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
227 use by PCI
228 Format: <irq>,<irq>...
229
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
231
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
234
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
239
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530240 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
244
Randy Dunlap4af94f32009-04-17 18:30:28 -0700245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
247
248 acpi_serialize [HW,ACPI] force serialization of AML methods
249
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
253
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
Amerigo Wangc3b07952011-05-10 21:09:38 +0200256 old_ordering, nonvs, sci_force_enable }
Randy Dunlap4af94f32009-04-17 18:30:28 -0700257 See Documentation/power/video.txt for information on
258 s3_bios and s3_mode.
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
Rafael J. Wysocki72ad5d72010-07-23 22:59:09 +0200267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
Zhang Ruid7f0eea2009-12-30 15:36:42 +0800269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
Randy Dunlap4af94f32009-04-17 18:30:28 -0700272
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
276
Luca Tettamanti7e905602009-03-30 00:01:27 +0200277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
292
Randy Dunlap4af94f32009-04-17 18:30:28 -0700293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
295
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700296 agp= [AGP]
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
301
Randy Dunlapbcfde332010-06-07 17:10:38 -0700302 ALSA [HW,ALSA]
303 See Documentation/sound/alsa/alsa-parameters.txt
304
Russell Kingd944d542010-02-20 16:13:29 +0000305 alignment= [KNL,ARM]
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
309
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
317
Borislav Petkov8360ee22011-11-21 12:10:19 +0100318 32: only for 32-bit processes
319 64: only for 64-bit processes
Borislav Petkovdfb09f92011-08-05 15:15:08 +0200320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
322
Sedat Dilek89e0b9a2011-12-05 23:08:32 +0100323 amd_iommu= [HW,X86-64]
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
329 is a lot of faster
Joerg Roedela5235722010-05-11 17:12:33 +0200330 off - do not initialize any AMD IOMMU found in
331 the system
Joerg Roedel5abcdba2011-12-01 15:49:45 +0100332 force_isolation - Force device isolation for all
333 devices. The IOMMU driver is not
334 allowed anymore to lift isolation
335 requirements as needed. This option
336 does not override iommu=pt
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 amijoy.map= [HW,JOY] Amiga joystick support
339 Map of devices attached to JOY0DAT and JOY1DAT
340 Format: <a>,<b>
Paul Bolle395cf962011-08-15 02:02:26 +0200341 See also Documentation/input/joystick.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342
343 analog.map= [HW,JOY] Analog joystick and gamepad support
344 Specifies type or capabilities of an analog joystick
345 connected to one of 16 gameports
346 Format: <type1>,<type2>,..<type16>
347
Randy Dunlapa9913042005-10-23 12:57:11 -0700348 apc= [HW,SPARC]
349 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 Format: noidle
351 Disable APC CPU standby support. SPARCstation-Fox does
352 not play well with APC CPU idle - disable it if you have
353 APC and your system crashes randomly.
354
Randy Dunlapca1eda22009-05-06 16:02:58 -0700355 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700356 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 Format: { quiet (default) | verbose | debug }
358 Change the amount of debugging information output
359 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700360
Brian Haleyb0f83b22010-02-04 13:36:50 -0800361 autoconf= [IPV6]
362 See Documentation/networking/ipv6.txt.
363
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400364 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
365 Limit apic dumping. The parameter defines the maximal
366 number of local apics being dumped. Also it is possible
367 to set it to "all" by meaning -- no limit here.
368 Format: { 1 (default) | 2 | ... | all }.
369 The parameter valid if only apic=debug or
370 apic=verbose is specified.
371 Example: apic=debug show_lapic=all
372
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700374 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
377 Format: <io>,<irq>,<nodeID>
378
379 ataflop= [HW,M68k]
380
381 atarimouse= [HW,MOUSE] Atari Mouse
382
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
384 EzKey and similar keyboards
385
386 atkbd.reset= [HW] Reset keyboard during initialization
387
Randy Dunlapa9913042005-10-23 12:57:11 -0700388 atkbd.set= [HW] Select keyboard code set
389 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
391 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
392 keyboards
393
394 atkbd.softraw= [HW] Choose between synthetic and real raw mode
395 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700396
397 atkbd.softrepeat= [HW]
398 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
Randy Dunlap16290242011-08-13 12:34:52 -0700400 autotest [IA-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 baycom_epp= [HW,AX25]
403 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700404
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
406 Format: <io>,<mode>
407 See header of drivers/net/hamradio/baycom_par.c.
408
Randy Dunlapa9913042005-10-23 12:57:11 -0700409 baycom_ser_fdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 Format: <io>,<irq>,<mode>[,<baud>]
412 See header of drivers/net/hamradio/baycom_ser_fdx.c.
413
Randy Dunlapa9913042005-10-23 12:57:11 -0700414 baycom_ser_hdx= [HW,AX25]
415 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 Format: <io>,<irq>,<mode>
417 See header of drivers/net/hamradio/baycom_ser_hdx.c.
418
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700419 boot_delay= Milliseconds to delay each printk during boot.
420 Values larger than 10 seconds (10000) are changed to
421 no delay (0).
422 Format: integer
423
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700424 bootmem_debug [KNL] Enable bootmem allocator debug messages.
425
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700427 bttv.radio= Most important insmod options are available as
428 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
Paul Bolle395cf962011-08-15 02:02:26 +0200430 bttv.tuner=
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000432 bulk_remove=off [PPC] This parameter disables the use of the pSeries
433 firmware feature for flushing multiple hpte entries
434 at a time.
435
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 c101= [NET] Moxa C101 synchronous serial card
437
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700438 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 Sometimes CPU hardware bugs make them report the cache
440 size incorrectly. The kernel will attempt work arounds
441 to fix known problems, but for some CPUs it is not
442 possible to determine what the correct size should be.
443 This option provides an override for these situations.
444
James Morris20510f22007-10-16 23:31:32 -0700445 capability.disable=
446 [SECURITY] Disable capabilities. This would normally
447 be used only if an alternative security model is to be
448 configured. Potentially dangerous and should only be
449 used if you are entirely sure of the consequences.
450
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100451 ccw_timeout_log [S390]
452 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453
Paul Menage8bab8dd2008-04-04 14:29:57 -0700454 cgroup_disable= [KNL] Disable a particular controller
455 Format: {name of the controller(s) to disable}
456 {Currently supported controllers - "memory"}
457
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 checkreqprot [SELINUX] Set initial checkreqprot flag value.
459 Format: { "0" | "1" }
460 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700461 0 -- check protection applied by kernel (includes
462 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 1 -- check protection requested by application.
464 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700465 Value can be changed at runtime via
466 /selinux/checkreqprot.
467
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100468 cio_ignore= [S390]
469 See Documentation/s390/CommonIO for details.
470
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700471 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700472 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200473 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700474 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200475 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 Format: { pit | tsc | cyclone | pmtmr }
477
John Stultz592913e2010-07-13 17:56:20 -0700478 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700479 Format: <string>
480 Override the default clocksource and use the clocksource
481 with the name specified.
482 Some clocksource names to choose from, depending on
483 the platform:
484 [all] jiffies (this is the base, fallback clocksource)
485 [ACPI] acpi_pm
486 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
487 pxa_timer,timer3,32k_counter,timer0_1
488 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700489 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700490 scx200_hrt on Geode; cyclone on IBM x440
491 [MIPS] MIPS
492 [PARISC] cr16
493 [S390] tod
494 [SH] SuperH
495 [SPARC64] tick
496 [X86-64] hpet,tsc
497
Andi Kleenac72e782008-01-30 13:33:21 +0100498 clearcpuid=BITNUM [X86]
499 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800500 arch/x86/include/asm/cpufeature.h for the valid bit
501 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100502 stable over kernel options, but the vendor specific
503 ones should be.
504 Also note that user programs calling CPUID directly
505 or using the feature without checking anything
506 will still see it. This just prevents it from
507 being used by the kernel or shown in /proc/cpuinfo.
508 Also note the kernel might malfunction if you disable
509 some critical bits.
510
Marek Szyprowski55bb0332011-12-29 13:09:51 +0100511 cma=nn[MG] [ARM,KNL]
512 Sets the size of kernel global memory area for contiguous
513 memory allocations. For more information, see
514 include/linux/dma-contiguous.h
515
Robert Jennings14f966e2009-04-15 05:55:32 +0000516 cmo_free_hint= [PPC] Format: { yes | no }
517 Specify whether pages are marked as being inactive
518 when they are freed. This is used in CMO environments
519 to determine OS memory pressure for page stealing by
520 a hypervisor.
521 Default: yes
522
Marek Szyprowskid4398df2011-12-29 13:09:51 +0100523 coherent_pool=nn[KMG] [ARM,KNL]
524 Sets the size of memory pool for coherent, atomic dma
Marek Szyprowskicb4d7a62012-07-30 09:11:33 +0200525 allocations, by default set to 256K.
Marek Szyprowskid4398df2011-12-29 13:09:51 +0100526
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530527 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100528 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100529 Range: 0 - 8192
530 Default: 64
531
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700533 Format:
534 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535
536 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
537 Format: <io>[,<irq>]
538
Randy Dunlapa9913042005-10-23 12:57:11 -0700539 com90xx= [HW,NET]
540 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 Format: <io>[,<irq>[,<memstart>]]
542
543 condev= [HW,S390] console device
544 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700545
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 console= [KNL] Output console device and options.
547
548 tty<n> Use the virtual console device <n>.
549
550 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800551 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800553 the form "bbbbpnf", where "bbbb" is the baud rate,
554 "p" is parity ("n", "o", or "e"), "n" is number of
555 bits, and "f" is flow control ("r" for RTS or
556 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800558 See Documentation/serial-console.txt for more
559 information. See
560 Documentation/networking/netconsole.txt for an
561 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700563 uart[8250],io,<addr>[,options]
564 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 Start an early, polled-mode console on the 8250/16550
566 UART at the specified I/O port or MMIO address,
567 switching to the matching ttyS device later. The
568 options are the same as for ttyS, above.
569
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700570 If the device connected to the port is not a TTY but a braille
571 device, prepend "brl," before the device type, for instance
572 console=brl,ttyS0
573 For now, only VisioBraille is supported.
574
Daniel Mackf324edc2009-06-16 15:33:52 -0700575 consoleblank= [KNL] The console blank (screen saver) timeout in
576 seconds. Defaults to 10*60 = 10mins. A value of 0
577 disables the blank timer.
578
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800579 coredump_filter=
580 [KNL] Change the default value for
581 /proc/<pid>/coredump_filter.
582 See also Documentation/filesystems/proc.txt.
583
Len Brown62027ae2011-04-01 18:13:10 -0400584 cpuidle.off=1 [CPU_IDLE]
585 disable the cpuidle sub-system
586
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700588 Format:
589 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800591 crashkernel=size[KMG][@offset[KMG]]
592 [KNL] Using kexec, Linux can switch to a 'crash kernel'
593 upon panic. This parameter reserves the physical
594 memory region [offset, offset + size] for that kernel
595 image. If '@offset' is omitted, then a suitable offset
596 is selected automatically. Check
597 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700598
Bernhard Wallefb391592007-10-18 23:41:02 -0700599 crashkernel=range1:size1[,range2:size2,...][@offset]
600 [KNL] Same as above, but depends on the memory
601 in the running system. The syntax of range is
602 start-[end] where start and end are both
603 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800604 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 cs89x0_dma= [HW,NET]
607 Format: <dma>
608
609 cs89x0_media= [HW,NET]
610 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700611
Randy Dunlapa9913042005-10-23 12:57:11 -0700612 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 See header of drivers/s390/block/dasd_devmap.c.
614
615 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
616 (one device per port)
617 Format: <port#>,<type>
618 See also Documentation/input/joystick-parport.txt
619
Thomas Renningera648ec02010-08-06 16:11:02 +0200620 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
621 time. See Documentation/dynamic-debug-howto.txt for
622 details.
623
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 debug [KNL] Enable kernel debugging (events log level).
625
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700626 debug_locks_verbose=
627 [KNL] verbose self-tests
628 Format=<0|1>
629 Print debugging info while doing the locking API
630 self-tests.
631 We default to 0 (no extra messages), setting it to
632 1 will print _a lot_ more information - normally
633 only useful to kernel developers.
634
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700635 debug_objects [KNL] Enable object debugging
636
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500637 no_debug_objects
638 [KNL] Disable object debugging
639
Stanislaw Gruszkac0a32fc2012-01-10 15:07:28 -0800640 debug_guardpage_minorder=
641 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
642 parameter allows control of the order of pages that will
643 be intentionally kept free (and hence protected) by the
644 buddy allocator. Bigger value increase the probability
645 of catching random memory corruption, but reduce the
646 amount of memory for normal system use. The maximum
647 possible value is MAX_ORDER/2. Setting this parameter
648 to 1 or 2 should be enough to identify most random
649 memory corruption problems caused by bugs in kernel or
650 driver code when a CPU writes to (or reads from) a
651 random memory location. Note that there exists a class
652 of memory corruptions problems caused by buggy H/W or
653 F/W or by drivers badly programing DMA (basically when
654 memory is written at bus level and the CPU MMU is
655 bypassed) which are not detectable by
656 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
657 tracking down these problems.
658
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200659 debugpat [X86] Enable PAT debugging
660
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200661 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 Format: <area>[,<node>]
663 See also Documentation/networking/decnet.txt.
664
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700665 default_hugepagesz=
666 [same as hugepagesz=] The size of the default
667 HugeTLB page size. This is the size represented by
668 the legacy /proc/ hugepages APIs, used for SHM, and
669 default size when mounting hugetlbfs filesystems.
670 Defaults to the default architecture's huge page size
671 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700672
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 dhash_entries= [KNL]
674 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 digi= [HW,SERIAL]
677 IO parameters + enable/disable command.
678
679 digiepca= [HW,SERIAL]
680 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000681 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Brian Haleyb0f83b22010-02-04 13:36:50 -0800683 disable= [IPV6]
684 See Documentation/networking/ipv6.txt.
685
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000686 disable_ddw [PPC/PSERIES]
687 Disable Dynamic DMA Window support. Use this if
688 to workaround buggy firmware.
689
Brian Haleyb0f83b22010-02-04 13:36:50 -0800690 disable_ipv6= [IPV6]
691 See Documentation/networking/ipv6.txt.
692
Yinghai Lu95ffa242008-04-29 03:52:33 -0700693 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700694 The kernel tries to adjust MTRR layout from continuous
695 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700696 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700697
Yinghai Lu093af8d2008-01-30 13:33:32 +0100698 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100699 By default the kernel will trim any uncacheable
700 memory out of your available memory pool based on
701 MTRR settings. This parameter disables that behavior,
702 possibly causing your machine to run very slowly.
703
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530704 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700705 Disable PIN 1 of APIC timer
706 Can be useful to work around chipset bugs.
707
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700708 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
709 this option disables the debugging code at boot.
710
711 dma_debug_entries=<number>
712 This option allows to tune the number of preallocated
713 entries for DMA-API debugging code. One entry is
714 required per DMA-API allocation. Use this if the
715 DMA-API debugging code disables itself because the
716 architectural default is too low.
717
Joerg Roedel1745de52009-05-22 21:49:51 +0200718 dma_debug_driver=<driver_name>
719 With this option the DMA-API debugging driver
720 filter feature can be enabled at boot time. Just
721 pass the driver to filter for as the parameter.
722 The filter can be disabled or changed to another
723 driver later using sysfs.
724
Carsten Emdeda0df922012-03-18 22:37:33 +0100725 drm_kms_helper.edid_firmware=[<connector>:]<file>
726 Broken monitors, graphic adapters and KVMs may
727 send no or incorrect EDID data sets. This parameter
728 allows to specify an EDID data set in the
729 /lib/firmware directory that is used instead.
730 Generic built-in EDID data sets are used, if one of
731 edid/1024x768.bin, edid/1280x1024.bin,
732 edid/1680x1050.bin, or edid/1920x1080.bin is given
733 and no file with the same name exists. Details and
734 instructions how to build your own EDID data are
735 available in Documentation/EDID/HOWTO.txt. An EDID
736 data set will only be used for a particular connector,
737 if its name and a colon are prepended to the EDID
738 name.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 dscc4.setup= [NET]
741
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700742 earlycon= [KNL] Output early console device and options.
743 uart[8250],io,<addr>[,options]
744 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700745 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700746 Start an early, polled-mode console on the 8250/16550
747 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700748 MMIO inter-register address stride is either 8-bit
749 (mmio) or 32-bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700750 The options are the same as for ttyS, above.
751
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530752 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 earlyprintk=vga
754 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500755 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500756 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757
Randy Dunlapa9913042005-10-23 12:57:11 -0700758 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 takes over.
760
Yinghai Lu5c059172008-07-24 17:29:40 -0700761 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
763 Currently only ttyS0 and ttyS1 are supported.
764
765 Interaction with the standard serial driver is not
766 very good.
767
768 The VGA output is eventually overwritten by the real
769 console.
770
Jason Wessel97311912010-05-20 21:04:30 -0500771 ekgdboc= [X86,KGDB] Allow early kernel console debugging
772 ekgdboc=kbd
773
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300774 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500775 the boot argument: earlyprintk=vga
776
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700778 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 eisa_irq_edge= [PARISC,HW]
781 See header of drivers/parisc/eisa.c.
782
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700783 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700785 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
787 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100788 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +0200789 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -0700790 Documentation/block/deadline-iosched.txt for details.
791
Michael Holzheud3bf3792011-10-30 15:16:37 +0100792 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -0700793 Specifies physical address of start of kernel core
Michael Holzheud3bf3792011-10-30 15:16:37 +0100794 image elf header and optionally the size. Generally
795 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -0800796 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700798 enable_mtrr_cleanup [X86]
799 The kernel tries to adjust MTRR layout from continuous
800 to discrete, to make X server driver able to add WB
801 entry later. This parameter enables that.
802
Randy Dunlapca1eda22009-05-06 16:02:58 -0700803 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700804 Enable PIN 1 of APIC timer
805 Can be useful to work around chipset bugs
806 (in particular on some ATI chipsets).
807 The kernel tries to set a reasonable default.
808
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 enforcing [SELINUX] Set initial enforcing status.
810 Format: {"0" | "1"}
811 See security/selinux/Kconfig help text.
812 0 -- permissive (log only, no denials).
813 1 -- enforcing (deny and log).
814 Default value is 0.
815 Value can be changed at runtime via /selinux/enforce.
816
Huang Yinga08f82d2010-05-18 14:35:21 +0800817 erst_disable [ACPI]
818 Disable Error Record Serialization Table (ERST)
819 support.
820
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 ether= [HW,NET] Ethernet cards parameters
822 This option is obsoleted by the "netdev=" option, which
823 has equivalent usage. See its documentation for details.
824
Mimi Zohar7102ebc2011-05-12 18:33:20 -0400825 evm= [EVM]
826 Format: { "fix" }
827 Permit 'security.evm' to be updated regardless of
828 current integrity status.
829
Akinobu Mitade1ba092006-12-08 02:39:42 -0800830 failslab=
831 fail_page_alloc=
832 fail_make_request=[KNL]
833 General fault injection mechanism.
834 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +0200835 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -0800836
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000838 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839
Alex Chiangf13ae302008-05-08 14:03:23 -0600840 force_pal_cache_flush
841 [IA-64] Avoid check_sal_cache_flush which may hang on
842 buggy SAL_CACHE_FLUSH implementations. Using this
843 parameter will force ia64_sal_cache_flush to call
844 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
845
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100846 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400847 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100848 as early as possible in order to facilitate early
849 boot debugging.
850
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200851 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400852 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200853 If no parameter is passed, ftrace will dump
854 buffers of all CPUs, but if you pass orig_cpu, it will
855 dump only the buffer of the CPU that triggered the
856 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400857
858 ftrace_filter=[function-list]
859 [FTRACE] Limit the functions traced by the function
860 tracer at boot up. function-list is a comma separated
861 list of functions. This list can be changed at run
862 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -0700863 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400864
865 ftrace_notrace=[function-list]
866 [FTRACE] Do not trace the functions specified in
867 function-list. This list can be changed at run time
868 by the set_ftrace_notrace file in the debugfs
869 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100870
Stefan Assmann369bc182009-10-12 22:17:21 +0200871 ftrace_graph_filter=[function-list]
872 [FTRACE] Limit the top level callers functions traced
873 by the function graph tracer at boot up.
874 function-list is a comma separated list of functions
875 that can be changed at run time by the
876 set_graph_function file in the debugfs tracing directory.
877
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 gamecon.map[2|3]=
879 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
880 support via parallel port (up to 5 devices per port)
881 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
882 See also Documentation/input/joystick-parport.txt
883
884 gamma= [HW,DRM]
885
Yinghai Luaaf23042008-01-30 13:33:09 +0100886 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
887 Format: off | on
888 default: on
889
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700890 gcov_persist= [GCOV] When non-zero (default), profiling data for
891 kernel modules is saved and remains accessible via
892 debugfs, even when the module is unloaded/reloaded.
893 When zero, profiling data is discarded and associated
894 debugfs files are removed at module unload time.
895
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 gpt [EFI] Forces disk with valid GPT signature but
897 invalid Protective MBR to be treated as GPT.
898
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 hashdist= [KNL,NUMA] Large hashes allocated during boot
900 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -0700901 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700902 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
904 hcl= [IA-64] SGI's Hardware Graph compatibility layer
905
906 hd= [EIDE] (E)IDE hard drive subsystem geometry
907 Format: <cyl>,<head>,<sect>
908
Huang Yingea8c0712010-05-18 14:35:15 +0800909 hest_disable [ACPI]
910 Disable Hardware Error Source Table (HEST) support;
911 corresponding firmware-first mode error processing
912 logic will be disabled.
913
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
915 size of <nn>. This works even on boxes that have no
916 highmem otherwise. This also works to reduce highmem
917 size on bigger boxes.
918
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800919 highres= [KNL] Enable/disable high resolution timer mode.
920 Valid parameters: "on", "off"
921 Default: "on"
922
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 hisax= [HW,ISDN]
924 See Documentation/isdn/README.HiSax.
925
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700926 hlt [BUGS=ARM,SH]
927
928 hpet= [X86-32,HPET] option to control HPET usage
929 Format: { enable (default) | disable | force |
930 verbose }
931 disable: disable HPET and use PIT instead
932 force: allow force enabled of undocumented chips (ICH4,
933 VIA, nVidia)
934 verbose: show contents of HPET registers during setup
935
Andi Kleenb4718e62008-07-23 21:27:51 -0700936 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
937 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700938 On x86-64 and powerpc, this option can be specified
939 multiple times interleaved with hugepages= to reserve
940 huge pages of different sizes. Valid pages sizes on
941 x86-64 are 2M (when the CPU supports "pse") and 1G
942 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700943 Note that 1GB pages can only be allocated at boot time
944 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900945
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100946 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
947 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100948 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
949 If specified, z/VM IUCV HVC accepts connections
950 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100951
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700952 keep_bootcon [KNL]
953 Do not unregister boot console at start. This is only
954 useful for debugging when something happens in the window
955 between unregistering the boot console and initializing
956 the real console.
957
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700958 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700959 or register an additional I2C bus that is not
960 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700961 Format:
962 <bus_id>,<clkrate>
963
Jiri Kosina36d95732008-10-06 02:51:09 -0400964 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200966 i8042.dumbkbd [HW] Pretend that controller can only read data from
967 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 (Don't attempt to blink the leds)
969 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500970 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400971 i8042.noloop [HW] Disable the AUX Loopback command while probing
972 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 i8042.nomux [HW] Don't check presence of an active multiplexing
974 controller
975 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
976 controllers
Masanari Iida24775d62012-02-15 00:26:42 +0900977 i8042.notimeout [HW] Ignore timeout condition signalled by controller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 i8042.reset [HW] Reset the controller during init and cleanup
979 i8042.unlock [HW] Unlock (ignore) the keylock
980
981 i810= [HW,DRM]
982
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700983 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
984 indicates that the driver is running on unsupported
985 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
987 does not match list of supported models.
988 i8k.power_status
989 [HW] Report power status in /proc/i8k
990 (disabled by default)
991 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
992 capability is set.
993
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 icn= [HW,ISDN]
995 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
996
David Fries0af80c02009-02-25 20:28:21 +0100997 ide-core.nodma= [HW] (E)IDE subsystem
998 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200999 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1000 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +01001001 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001003 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1004 Claim all unknown PCI IDE storage controllers.
1005
Andi Kleenf039b752007-05-02 19:27:12 +02001006 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001007 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
1008 Poll forces a polling idle loop that can slightly
1009 improve the performance of waking up a idle CPU, but
1010 will use a lot of power and make the system run hot.
1011 Not recommended.
1012 idle=mwait: On systems which support MONITOR/MWAIT but
1013 the kernel chose to not use it because it doesn't save
1014 as much power as a normal idle loop, use the
1015 MONITOR/MWAIT idle loop anyways. Performance should be
1016 the same as idle=poll.
1017 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +08001018 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001019 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -07001020
Ingo Molnar792908222006-12-06 20:40:51 -08001021 ignore_loglevel [KNL]
1022 Ignore loglevel setting - this will print /all/
1023 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001024 We also add it as printk module parameter, so users
1025 could change it dynamically, usually by
1026 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -08001027
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 ihash_entries= [KNL]
1029 Set number of hash buckets for inode cache.
1030
Mimi Zohar3323eec2009-02-04 09:06:58 -05001031 ima_audit= [IMA]
1032 Format: { "0" | "1" }
1033 0 -- integrity auditing messages. (Default)
1034 1 -- enable informational integrity auditing messages.
1035
1036 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -07001037 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -05001038 default: "sha1"
1039
Eric Paris5789ba32009-05-21 15:47:06 -04001040 ima_tcb [IMA]
1041 Load a policy which meets the needs of the Trusted
1042 Computing Base. This means IMA will measure all
1043 programs exec'd, files mmap'd for exec, and all files
1044 opened for read by uid=0.
1045
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 init= [KNL]
1047 Format: <full_path>
1048 Run specified binary instead of /sbin/init as init
1049 process.
1050
1051 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1052 for working out where the kernel is dying during
1053 startup.
1054
1055 initrd= [BOOT] Specify the location of the initial ramdisk
1056
1057 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1058 Format: <irq>
1059
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001060 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001061 on
1062 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001063 off
1064 Disable intel iommu driver.
1065 igfx_off [Default Off]
1066 By default, gfx is mapped as normal device. If a gfx
1067 device has a dedicated DMAR unit, the DMAR unit is
1068 bypassed by not enabling DMAR with this option. In
1069 this case, gfx device will use physical address for
1070 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001071 forcedac [x86_64]
1072 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001073 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001074 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001075 than 32-bit addressing. The default is to look
1076 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001077 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001078 strict [Default Off]
1079 With this option on every unmap_single operation will
1080 result in a hardware IOTLB flush operation as opposed
1081 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001082 sp_off [Default Off]
1083 By default, super page will be supported if Intel IOMMU
1084 has the capability. With this option, super page will
1085 not be supported.
Masanari Iida2e92c7a2011-12-15 01:18:52 +09001086
1087 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1088 0 disables intel_idle and fall back on acpi_idle.
1089 1 to 6 specify maximum depth of C-state.
1090
Chris Wrightd1423d52010-07-20 11:06:49 -07001091 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001092 on enable Interrupt Remapping (default)
1093 off disable Interrupt Remapping
1094 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001095 no_x2apic_optout
1096 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001097
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001098 iomem= Disable strict checking of access to MMIO memory
1099 strict regions from userspace.
1100 relaxed
1101
1102 iommu= [x86]
1103 off
1104 force
1105 noforce
1106 biomerge
1107 panic
1108 nopanic
1109 merge
1110 nomerge
1111 forcesac
1112 soft
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001113 pt [x86, IA-64]
1114 group_mf [x86, IA-64]
1115
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001116
1117 io7= [HW] IO7 for Marvel based alpha systems
1118 See comment before marvel_specify_io7 in
1119 arch/alpha/kernel/core_marvel.c.
1120
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301121 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001122 0x80
1123 Standard port 0x80 based delay
1124 0xed
1125 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001126 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001127 Simple two microseconds delay
1128 none
1129 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001130
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001132 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133
1134 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001135 See comment before ip2_setup() in
1136 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137
Alan Cox200803d2005-06-28 20:45:18 -07001138 irqfixup [HW]
1139 When an interrupt is not handled search all handlers
1140 for it. Intended to get systems with badly broken
1141 firmware running.
1142
1143 irqpoll [HW]
1144 When an interrupt is not handled search all handlers
1145 for it. Also check all handlers each timer
1146 interrupt. Intended to get systems with badly broken
1147 firmware running.
1148
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001150 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151
1152 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001153 Format:
1154 <cpu number>,...,<cpu number>
1155 or
Li Zefanb225d442008-11-06 12:53:39 -08001156 <cpu number>-<cpu number>
1157 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001158 or a mixture
1159 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001160
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 This option can be used to specify one or more CPUs
1162 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001163 algorithms. You can move a process onto or off an
1164 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 <cpu number> begins at 0 and the maximum value is
1166 "number of CPUs in system - 1".
1167
1168 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001169 alternative -- manually setting the CPU mask of all
1170 tasks in the system -- can cause problems and
1171 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
Randy Dunlapa9913042005-10-23 12:57:11 -07001173 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174
1175 js= [HW,JOY] Analog joystick
1176 See Documentation/input/joystick.txt.
1177
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001178 keepinitrd [HW,ARM]
1179
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301180 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001181 specifies the amount of memory usable by the kernel
1182 for non-movable allocations. The requested amount is
1183 spread evenly throughout all nodes in the system. The
1184 remaining memory in each node is used for Movable
1185 pages. In the event, a node is too small to have both
1186 kernelcore and Movable pages, kernelcore pages will
1187 take priority and other nodes will have a larger number
1188 of kernelcore pages. The Movable zone is used for the
1189 allocation of pages that may be reclaimed or moved
1190 by the page migration subsystem. This means that
1191 HugeTLB pages may not be allocated from this zone.
1192 Note that allocations like PTEs-from-HighMem still
1193 use the HighMem zone if it exists, and the Normal
1194 zone if it does not.
1195
Jason Wessel4fe1da42010-05-20 21:04:31 -05001196 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1197 Format: <Controller#>[,poll interval]
1198 The controller # is the number of the ehci usb debug
1199 port as it is probed via PCI. The poll interval is
1200 optional and is the number seconds in between
1201 each poll cycle to the debug port in case you need
1202 the functionality for interrupting the kernel with
1203 gdb or control-c on the dbgp connection. When
1204 not using this parameter you use sysrq-g to break into
1205 the kernel debugger.
1206
Jason Wessel84c08fd2010-05-20 21:04:24 -05001207 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001208 Requires a tty driver that supports console polling,
1209 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001210 Serial only format: <serial_device>[,baud]
1211 keyboard only format: kbd
1212 keyboard and serial format: kbd,<serial_device>[,baud]
1213 Optional Kernel mode setting:
1214 kms, kbd format: kms,kbd
1215 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001216
Jason Wessel84c08fd2010-05-20 21:04:24 -05001217 kgdbwait [KGDB] Stop kernel execution and enter the
1218 kernel debugger at the earliest opportunity.
1219
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001220 kmac= [MIPS] korina ethernet MAC address.
1221 Configure the RouterBoard 532 series on-chip
1222 Ethernet adapter MAC address.
1223
Catalin Marinas04f70332009-06-11 13:22:39 +01001224 kmemleak= [KNL] Boot-time kmemleak enable/disable
1225 Valid arguments: on, off
1226 Default: on
1227
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301228 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001229 in oops dumps.
1230
Andre Przywarafef07aa2009-07-10 14:20:35 +02001231 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1232 Default is 0 (don't ignore, but inject #GP)
1233
Xiao Guangronga182d872010-09-20 22:17:48 +08001234 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1235 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001236 Default is 0 (off)
1237
Andre Przywarafef07aa2009-07-10 14:20:35 +02001238 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001239 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001240
1241 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1242 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001243 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001244
Andre Przywarafef07aa2009-07-10 14:20:35 +02001245 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1246 (virtualized MMU) support on capable Intel chips.
1247 Default is 1 (enabled)
1248
1249 kvm-intel.emulate_invalid_guest_state=
1250 [KVM,Intel] Enable emulation of invalid guest states
1251 Default is 0 (disabled)
1252
1253 kvm-intel.flexpriority=
1254 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1255 Default is 1 (enabled)
1256
Sasha Levine1a72ae2011-08-09 14:28:35 +03001257 kvm-intel.nested=
1258 [KVM,Intel] Enable VMX nesting (nVMX).
1259 Default is 0 (disabled)
1260
Andre Przywarafef07aa2009-07-10 14:20:35 +02001261 kvm-intel.unrestricted_guest=
1262 [KVM,Intel] Disable unrestricted guest feature
1263 (virtualized real and unpaged mode) on capable
1264 Intel chips. Default is 1 (enabled)
1265
1266 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1267 feature (tagged TLBs) on capable Intel chips.
1268 Default is 1 (enabled)
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 l2cr= [PPC]
1271
Robert Brosea78bfbf2008-03-29 07:20:23 +11001272 l3cr= [PPC]
1273
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001274 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001275 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301277 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001278 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001279
FD Camifcb71f62008-01-06 19:08:56 +01001280 libata.dma= [LIBATA] DMA control
1281 libata.dma=0 Disable all PATA and SATA DMA
1282 libata.dma=1 PATA and SATA Disk DMA only
1283 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001284 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001285 Combinations also work, so libata.dma=3 enables DMA
1286 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001287
Michael Prokop20308872009-08-06 00:14:10 +02001288 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1289 libata.ignore_hpa=0 keep BIOS limits (default)
1290 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001291
Dave Jones78e70c22007-09-27 11:50:13 -04001292 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1293 when set.
1294 Format: <int>
1295
Tejun Heo33267322008-02-13 09:15:09 +09001296 libata.force= [LIBATA] Force configurations. The format is comma
1297 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f3092010-04-21 12:17:12 +02001298 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001299 matching port, link or device. Basically, it matches
1300 the ATA ID string printed on console by libata. If
1301 the whole ID part is omitted, the last PORT and DEVICE
1302 values are used. If ID hasn't been specified yet, the
1303 configuration applies to all ports, links and devices.
1304
1305 If only DEVICE is omitted, the parameter applies to
1306 the port and all links and devices behind it. DEVICE
1307 number of 0 either selects the first device or the
1308 first fan-out link behind PMP device. It does not
1309 select the host link. DEVICE number of 15 selects the
1310 host link and device attached to it.
1311
1312 The VAL specifies the configuration to force. As long
1313 as there's no ambiguity shortcut notation is allowed.
1314 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1315 The following configurations can be forced.
1316
1317 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1318 Any ID with matching PORT is used.
1319
1320 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1321
1322 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1323 udma[/][16,25,33,44,66,100,133] notation is also
1324 allowed.
1325
1326 * [no]ncq: Turn on or off NCQ.
1327
Tejun Heo05944bd2008-08-13 20:19:09 +09001328 * nohrst, nosrst, norst: suppress hard, soft
1329 and both resets.
1330
Tejun Heo43c9c592010-05-23 12:59:11 +02001331 * dump_id: dump IDENTIFY data.
1332
Tejun Heo33267322008-02-13 09:15:09 +09001333 If there are multiple matching configurations changing
1334 the same attribute, the last one is used.
1335
Yinghai Lu95f72d12010-07-12 14:36:09 +10001336 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001337
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001339 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001341 lockd.nlm_grace_period=P [NFS] Assign grace period.
1342 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001344 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1345 Format: <integer>
1346
1347 lockd.nlm_timeout=T [NFS] Assign timeout value.
1348 Format: <integer>
1349
1350 lockd.nlm_udpport=M [NFS] Assign UDP port.
1351 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
1353 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1354 Format: <irq>
1355
1356 loglevel= All Kernel Messages with a loglevel smaller than the
1357 console loglevel will be printed to the console. It can
1358 also be changed with klogd or other programs. The
1359 loglevels are defined as follows:
1360
1361 0 (KERN_EMERG) system is unusable
1362 1 (KERN_ALERT) action must be taken immediately
1363 2 (KERN_CRIT) critical conditions
1364 3 (KERN_ERR) error conditions
1365 4 (KERN_WARNING) warning conditions
1366 5 (KERN_NOTICE) normal but significant condition
1367 6 (KERN_INFO) informational
1368 7 (KERN_DEBUG) debug-level messages
1369
Randy Dunlapc756d082011-02-20 20:08:35 -08001370 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1371 in bytes. n must be a power of two. The default
1372 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373
Randy Dunlapaccaa242007-10-16 01:29:37 -07001374 logo.nologo [FB] Disables display of the built-in Linux logo.
1375 This may be used to provide more screen space for
1376 kernel log messages and is useful when debugging
1377 kernel boot problems.
1378
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 lp=0 [LP] Specify parallel ports to use, e.g,
1380 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1381 lp=reset first parallel port). 'lp=0' disables the
1382 lp=auto printer driver. 'lp=reset' (which can be
1383 specified in addition to the ports) causes
1384 attached printers to be reset. Using
1385 lp=port1,port2,... specifies the parallel ports
1386 to associate lp devices with, starting with
1387 lp0. A port specification may be 'none' to skip
1388 that lp device, or a parport name such as
1389 'parport0'. Specifying 'lp=auto' instead of a
1390 port specification list means that device IDs
1391 from each port should be examined, to see if
1392 an IEEE 1284-compliant printer is attached; if
1393 so, the driver will manage that printer.
1394 See also header of drivers/char/lp.c.
1395
1396 lpj=n [KNL]
1397 Sets loops_per_jiffy to given constant, thus avoiding
1398 time-consuming boot-time autodetection (up to 250 ms per
1399 CPU). 0 enables autodetection (default). To determine
1400 the correct value for your kernel, boot with normal
1401 autodetection and see what value is printed. Note that
1402 on SMP systems the preset will be applied to all CPUs,
1403 which is likely to cause problems if your CPUs need
1404 significantly divergent settings. An incorrect value
1405 will cause delays in the kernel to be wrong, leading to
1406 unpredictable I/O errors and other breakage. Although
1407 unlikely, in the extreme case this might damage your
1408 hardware.
1409
1410 ltpc= [NET]
1411 Format: <io>,<irq>,<dma>
1412
Randy Dunlap16290242011-08-13 12:34:52 -07001413 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001414 (machvec) in a generic kernel.
1415 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416
Wu Zhangjin3209e702009-07-02 23:27:12 +08001417 machtype= [Loongson] Share the same kernel image file between different
1418 yeeloong laptop.
1419 Example: machtype=lemote-yeeloong-2f-7inch
1420
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001421 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1422 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423
1424 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001425 should make use of. maxcpus=n : n >= 0 limits the
1426 kernel to using 'n' processors. n=0 is a special case,
1427 it is equivalent to "nosmp", which also disables
1428 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429
Kay Sieversd134b002011-07-31 22:08:04 +02001430 max_loop= [LOOP] The number of loop block devices that get
1431 (loop.max_loop) unconditionally pre-created at init time. The default
1432 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1433 of statically allocating a predefined number, loop
1434 devices can be requested on-demand with the
1435 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 mcatest= [IA-64]
1438
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001439 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440
Uwe Hermann71cced62008-10-20 09:32:21 -07001441 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 md= [HW] RAID subsystems devices and level
1444 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001445
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446 mdacon= [MDA]
1447 Format: <first>,<last>
1448 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001449
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1451 Amount of memory to be used when the kernel is not able
1452 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001453 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454 address space collisions. Without memmap= PCI devices
1455 could be placed at addresses belonging to unused RAM.
1456
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001457 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 memory.
1459
Paul Mundt6902aa82008-09-21 17:14:42 +09001460 memchunk=nn[KMG]
1461 [KNL,SH] Allow user to override the default size for
1462 per-device physically contiguous DMA buffers.
1463
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301464 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 E820 memory map, as specified by the user.
1466 Such memmap=exactmap lines can be constructed based on
1467 BIOS output or other requirements. See the memmap=nn@ss
1468 option description.
1469
1470 memmap=nn[KMG]@ss[KMG]
1471 [KNL] Force usage of a specific region of memory
1472 Region of memory to be used, from ss to ss+nn.
1473
1474 memmap=nn[KMG]#ss[KMG]
1475 [KNL,ACPI] Mark specific memory as ACPI data.
1476 Region of memory to be used, from ss to ss+nn.
1477
1478 memmap=nn[KMG]$ss[KMG]
1479 [KNL,ACPI] Mark specific memory as reserved.
1480 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001481 Example: Exclude memory from 0x18690000-0x1869ffff
1482 memmap=64K$0x18690000
1483 or
1484 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001486 memory_corruption_check=0/1 [X86]
1487 Some BIOSes seem to corrupt the first 64k of
1488 memory when doing things like suspend/resume.
1489 Setting this option will scan the memory
1490 looking for corruption. Enabling this will
1491 both detect corruption and prevent the kernel
1492 from using the memory being corrupted.
1493 However, its intended as a diagnostic tool; if
1494 repeatable BIOS-originated corruption always
1495 affects the same memory, you can use memmap=
1496 to prevent the kernel from using that memory.
1497
1498 memory_corruption_check_size=size [X86]
1499 By default it checks for corruption in the low
1500 64k, making this memory unavailable for normal
1501 use. Use this parameter to scan for
1502 corruption in more or less memory.
1503
1504 memory_corruption_check_period=seconds [X86]
1505 By default it checks for corruption every 60
1506 seconds. Use this parameter to check at some
1507 other rate. 0 disables periodic checking.
1508
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001509 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001510 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001511 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001512 Specifies the number of memtest passes to be
1513 performed. Each pass selects another test
1514 pattern from a given set of patterns. Memtest
1515 fills the memory with this pattern, validates
1516 memory contents and reserves bad memory
1517 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001518
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 meye.*= [HW] Set MotionEye Camera parameters
1520 See Documentation/video4linux/meye.txt.
1521
Andres Salomon8f368812007-10-12 23:04:06 +02001522 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1523 Multi-Function General Purpose Timers on AMD Geode
1524 platforms.
1525
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001526 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1527 the BIOS has incorrectly applied a workaround. TinyBIOS
1528 version 0.98 is known to be affected, 0.99 fixes the
1529 problem by letting the user disable the workaround.
1530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 mga= [HW,DRM]
1532
Randy Dunlap1c207f92008-11-19 15:36:16 -08001533 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1534 physical address is ignored.
1535
Michel Pollet39f45d72009-05-20 11:10:31 +01001536 mini2440= [ARM,HW,KNL]
1537 Format:[0..2][b][c][t]
1538 Default: "0tb"
1539 MINI2440 configuration specification:
1540 0 - The attached screen is the 3.5" TFT
1541 1 - The attached screen is the 7" TFT
1542 2 - The VGA Shield is attached (1024x768)
1543 Leaving out the screen size parameter will not load
1544 the TFT driver, and the framebuffer will be left
1545 unconfigured.
1546 b - Enable backlight. The TFT backlight pin will be
1547 linked to the kernel VESA blanking code and a GPIO
1548 LED. This parameter is not necessary when using the
1549 VGA shield.
1550 c - Enable the s3c camera interface.
1551 t - Reserved for enabling touchscreen support. The
1552 touchscreen support is not enabled in the mainstream
1553 kernel as of 2.6.30, a preliminary port can be found
1554 in the "bleeding edge" mini2440 support kernel at
1555 http://repo.or.cz/w/linux-2.6/mini2440.git
1556
Mel Gorman6b74ab92008-07-23 21:26:49 -07001557 mminit_loglevel=
1558 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1559 parameter allows control of the logging verbosity for
1560 the additional memory initialisation checks. A value
1561 of 0 disables mminit logging and a level of 4 will
1562 log everything. Information is printed at KERN_DEBUG
1563 so loglevel=8 may also need to be specified.
1564
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 mousedev.tap_time=
1566 [MOUSE] Maximum time between finger touching and
1567 leaving touchpad surface for touch to be considered
1568 a tap and be reported as a left button click (for
1569 touchpads working in absolute mode only).
1570 Format: <msecs>
1571 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1572 reporting absolute coordinates, such as tablets
1573 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1574 reporting absolute coordinates, such as tablets
1575
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301576 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001577 is similar to kernelcore except it specifies the
1578 amount of memory used for migratable allocations.
1579 If both kernelcore and movablecore is specified,
1580 then kernelcore will be at *least* the specified
1581 value but may be more. If movablecore on its own
1582 is specified, the administrator must be careful
1583 that the amount of memory usable for all allocations
1584 is not too small.
1585
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 MTD_Partition= [MTD]
1587 Format: <name>,<region-number>,<size>,<offset>
1588
Randy Dunlapa9913042005-10-23 12:57:11 -07001589 MTD_Region= [MTD] Format:
1590 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591
1592 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001593 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001595 multitce=off [PPC] This parameter disables the use of the pSeries
1596 firmware feature for updating multiple TCE entries
1597 at a time.
1598
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001599 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1600
1601 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1602
1603 boundary - index of last SLC block on Flex-OneNAND.
1604 The remaining blocks are configured as MLC blocks.
1605 lock - Configure if Flex-OneNAND boundary should be locked.
1606 Once locked, the boundary cannot be changed.
1607 1 indicates lock status, 0 indicates unlock status.
1608
Ben Dooks9db829f2008-07-03 11:24:29 +01001609 mtdset= [ARM]
1610 ARM/S3C2412 JIVE boot control
1611
1612 See arch/arm/mach-s3c2412/mach-jive.c
1613
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001615 [HW] Make the MicroTouch USB driver use raw coordinates
1616 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001618 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001619 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001620 that could hold holes aka. UC entries.
1621
1622 mtrr_gran_size=nn[KMG] [X86]
1623 Used for mtrr cleanup. It is granularity of mtrr block.
1624 Default is 1.
1625 Large value could prevent small alignment from
1626 using up MTRRs.
1627
1628 mtrr_spare_reg_nr=n [X86]
1629 Format: <integer>
1630 Range: 0,7 : spare reg number
1631 Default : 1
1632 Used for mtrr cleanup. It is spare mtrr entries number.
1633 Set to 2 or more if your graphical card needs more.
1634
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 netdev= [NET] Network devices parameters
1638 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1639 Note that mem_start is often overloaded to mean
1640 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001641 This usage is only documented in each driver source
1642 file if at all.
1643
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001644 nf_conntrack.acct=
1645 [NETFILTER] Enable connection tracking flow accounting
1646 0 to disable accounting
1647 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001648 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001649
Chuck Lever306a0752010-09-17 10:54:37 -04001650 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001651 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652
1653 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001654 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655
Chuck Lever306a0752010-09-17 10:54:37 -04001656 nfsrootdebug [NFS] enable nfsroot debugging messages.
1657 See Documentation/filesystems/nfs/nfsroot.txt.
1658
Trond Myklebusta72b4422006-01-03 09:55:41 +01001659 nfs.callback_tcpport=
1660 [NFS] set the TCP port on which the NFSv4 callback
1661 channel should listen.
1662
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001663 nfs.cache_getent=
1664 [NFS] sets the pathname to the program which is used
1665 to update the NFS client cache entries.
1666
1667 nfs.cache_getent_timeout=
1668 [NFS] sets the timeout after which an attempt to
1669 update a cache entry is deemed to have failed.
1670
Trond Myklebust58df0952006-01-03 09:55:57 +01001671 nfs.idmap_cache_timeout=
1672 [NFS] set the maximum lifetime for idmapper cache
1673 entries.
1674
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001675 nfs.enable_ino64=
1676 [NFS] enable 64-bit inode numbers.
1677 If zero, the NFS client will fake up a 32-bit inode
1678 number for the readdir() and stat() syscalls instead
1679 of returning the full 64-bit number.
1680 The default is to return 64-bit inode numbers.
1681
Trond Myklebustef159e92012-02-06 19:50:40 -05001682 nfs.max_session_slots=
1683 [NFSv4.1] Sets the maximum number of session slots
1684 the client will attempt to negotiate with the server.
1685 This limits the number of simultaneous RPC requests
1686 that the client can send to the NFSv4.1 server.
1687 Note that there is little point in setting this
1688 value higher than the max_tcp_slot_table_limit.
1689
Trond Myklebustb064eca22011-02-22 15:44:32 -08001690 nfs.nfs4_disable_idmapping=
Trond Myklebust074b1d12012-01-09 13:46:26 -05001691 [NFSv4] When set to the default of '1', this option
1692 ensures that both the RPC level authentication
1693 scheme and the NFS level operations agree to use
1694 numeric uids/gids if the mount is using the
1695 'sec=sys' security flavour. In effect it is
1696 disabling idmapping, which can make migration from
1697 legacy NFSv2/v3 systems to NFSv4 easier.
1698 Servers that do not support this mode of operation
1699 will be autodetected by the client, and it will fall
1700 back to using the idmapper.
1701 To turn off this behaviour, set the value to '0'.
Trond Myklebustb064eca22011-02-22 15:44:32 -08001702
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05001703 nfs.send_implementation_id =
1704 [NFSv4.1] Send client implementation identification
1705 information in exchange_id requests.
1706 If zero, no implementation identification information
1707 will be sent.
1708 The default is to send the implementation identification
1709 information.
1710
J. Bruce Fieldse9541ce2012-03-22 16:07:18 -04001711 nfsd.nfs4_disable_idmapping=
1712 [NFSv4] When set to the default of '1', the NFSv4
1713 server will return only numeric uids and gids to
1714 clients using auth_sys, and will accept numeric uids
1715 and gids from such clients. This is intended to ease
1716 migration from NFSv2/v3.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05001717
Sachin Bhamare18d98f62012-03-19 20:47:58 -07001718 objlayoutdriver.osd_login_prog=
1719 [NFS] [OBJLAYOUT] sets the pathname to the program which
1720 is used to automatically discover and login into new
1721 osd-targets. Please see:
1722 Documentation/filesystems/pnfs.txt for more explanations
1723
Paul Mundt1e1030d2009-09-01 17:38:32 +09001724 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001725 when a NMI is triggered.
1726 Format: [state][,regs][,debounce][,die]
1727
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301728 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001729 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001730 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001731 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001732 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001733 timeout occurs (or 'nopanic' to override the opposite
1734 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001735 This is useful when you use a panic=... timeout and
1736 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737
Anton Vorontsovbff38772009-07-08 11:10:56 -07001738 netpoll.carrier_timeout=
1739 [NET] Specifies amount of time (in seconds) that
1740 netpoll should wait for a carrier. By default netpoll
1741 waits 4 seconds.
1742
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001743 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 emulation library even if a 387 maths coprocessor
1745 is present.
1746
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001747 no_console_suspend
1748 [HW] Never suspend the console
1749 Disable suspending of consoles during suspend and
1750 hibernate operations. Once disabled, debugging
1751 messages can reach various consoles while the rest
1752 of the system is being put to sleep (ie, while
1753 debugging driver suspend/resume hooks). This may
1754 not work reliably with all consoles, but is known
1755 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07001756 To facilitate more flexible debugging, we also add
1757 console_suspend, a printk module parameter to control
1758 it. Users could use console_suspend (usually
1759 /sys/module/printk/parameters/console_suspend) to
1760 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001761
Christoph Lameterc1aee212007-05-31 00:40:47 -07001762 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1763 caches in the slab allocator. Saves per-node memory,
1764 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001765
Randy Dunlapa9913042005-10-23 12:57:11 -07001766 noalign [KNL,ARM]
1767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 noapic [SMP,APIC] Tells the kernel to not make use of any
1769 IOAPICs that may be present in the system.
1770
Mike Galbraith5091faa2010-11-30 14:18:03 +01001771 noautogroup Disable scheduler automatic task group creation.
1772
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 nobats [PPC] Do not use BATs for mapping kernel lowmem
1774 on "Classic" PPC cores.
1775
1776 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001777
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001778 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1779
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001780 nodelayacct [KNL] Disable per-task delay accounting
1781
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1783
Paul Mundt6902aa82008-09-21 17:14:42 +09001784 nodsp [SH] Disable hardware DSP at boot time.
1785
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301786 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001787
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 noexec [IA-64]
1789
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301790 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001791 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001793 noexec=off: disable non-executable mappings
1794
Fenghua Yude5397a2011-05-11 16:51:05 -07001795 nosmep [X86]
1796 Disable SMEP (Supervisor Mode Execution Protection)
1797 even if it is supported by processor.
1798
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001799 noexec32 [X86-64]
1800 This affects only 32-bit executables.
1801 noexec32=on: enable non-executable mappings (default)
1802 read doesn't imply executable mappings
1803 noexec32=off: disable non-executable mappings
1804 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805
Paul Mundt6902aa82008-09-21 17:14:42 +09001806 nofpu [SH] Disable hardware FPU at boot time.
1807
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001808 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001809 register save and restore. The kernel will only save
1810 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
Suresh Siddha0c752a92009-05-22 12:17:45 -07001812 noxsave [BUGS=X86] Disables x86 extended register state save
1813 and restore using xsave. The kernel will fallback to
1814 enabling legacy floating-point and sse state.
1815
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001816 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1817 wfi(ARM) instruction doesn't work correctly and not to
1818 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001819
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001820 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 instruction doesn't work correctly and not to
1822 use it.
1823
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001824 no_file_caps Tells the kernel not to honor file capabilities. The
1825 only way then for a file to be executed with privilege
1826 is to be setuid root or executed by root.
1827
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828 nohalt [IA-64] Tells the kernel not to use the power saving
1829 function PAL_HALT_LIGHT when idle. This increases
1830 power-consumption. On the positive side, it reduces
1831 interrupt wake-up latency, which may improve performance
1832 in certain environments such as networked servers or
1833 real-time systems.
1834
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001835 nohz= [KNL] Boottime enable/disable dynamic ticks
1836 Valid arguments: on, off
1837 Default: on
1838
Paul Mundteeee7852009-04-02 12:31:16 +09001839 noiotrap [SH] Disables trapped I/O port accesses.
1840
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001841 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001842 disable unhandled interrupt sources.
1843
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301844 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001845 broken timer IRQ sources.
1846
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 noisapnp [ISAPNP] Disables ISA PnP code.
1848
1849 noinitrd [RAM] Tells the kernel not to load any configured
1850 initial RAM disk.
1851
Weidong Han03ea8152009-04-17 16:42:15 +08001852 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1853 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001854 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001855
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 nointroute [IA-64]
1857
Randy Dunlap16290242011-08-13 12:34:52 -07001858 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07001859
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001860 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1861
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001862 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1863 fault handling.
1864
Glauber Costad910f5c2011-07-11 15:28:19 -04001865 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1866 steal time is computed, but won't influence scheduler
1867 behaviour
1868
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001869 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001871 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001872
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 noltlbs [PPC] Do not use large page/tlb entries for kernel
1874 lowmem mapping on PPC40x.
1875
Horms312f1f02006-02-22 09:57:55 +09001876 nomca [IA-64] Disable machine check abort handling
1877
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001878 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001879
Andres Salomon83d73842007-10-12 23:04:06 +02001880 nomfgpt [X86-32] Disable Multi-Function General Purpose
1881 Timer usage (for AMD Geode machines).
1882
Don Zickusbda62632011-10-13 15:14:27 -04001883 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
1884 shutdown the other cpus. Instead use the REBOOT_VECTOR
1885 irq.
1886
Dave Young02608be2012-02-01 10:33:14 +08001887 nomodule Disable module load
1888
Jiri Kosina016ddd92010-01-18 17:05:40 +01001889 nopat [X86] Disable PAT (page attribute table extension of
1890 pagetables) support.
1891
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001892 norandmaps Don't use address space randomization. Equivalent to
1893 echo 0 > /proc/sys/kernel/randomize_va_space
1894
Jiri Kosinabbff2162010-08-11 18:34:09 +02001895 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001896
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001897 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001898 with UP alternatives
1899
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900 noresidual [PPC] Don't use residual data on PReP machines.
1901
H. Peter Anvin49d859d2011-07-31 14:02:19 -07001902 nordrand [X86] Disable the direct use of the RDRAND
1903 instruction even if it is supported by the
1904 processor. RDRAND is still available to user
1905 space applications.
1906
Randy Dunlapa9913042005-10-23 12:57:11 -07001907 noresume [SWSUSP] Disables resume and restores original swap
1908 space.
1909
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 no-scroll [VGA] Disables scrollback.
1911 This is required for the Braillex ib80-piezo Braille
1912 reader made by F.H. Papenmeier (Germany).
1913
1914 nosbagart [IA-64]
1915
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001916 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001917
Len Brown61ec7562007-08-16 03:34:22 -04001918 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1919 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920
Dave Jones97842212007-07-15 23:41:05 -07001921 nosoftlockup [KNL] Disable the soft-lockup detector.
1922
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 nosync [HW,M68K] Disables sync negotiation for all devices.
1924
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001925 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926
1927 nousb [USB] Disable the USB subsystem
1928
Ben Hutchings55142372011-01-02 23:02:42 +00001929 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001930
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001932
Weidong Han2b2fd872009-04-17 16:42:12 +08001933 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1934
Randy Dunlap16290242011-08-13 12:34:52 -07001935 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07001936 purges which is reported from either PAL_VM_SUMMARY or
1937 SAL PALO.
1938
Yinghai Lu2b633e32010-02-10 01:20:37 -08001939 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1940 could support. nr_cpus=n : n >= 1 limits the kernel to
1941 supporting 'n' processors. Later in runtime you can not
1942 use hotplug cpu feature to put more cpu back to online.
1943 just like you compile the kernel NR_CPUS=n
1944
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001945 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1946
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001947 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1948 one of ['zone', 'node', 'default'] can be specified
1949 This can be set from sysctl after boot.
1950 See Documentation/sysctl/vm.txt for details.
1951
Randy Dunlap7c4be252009-01-06 14:42:44 -08001952 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1953 See Documentation/debugging-via-ohci1394.txt for more
1954 info.
1955
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001956 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1957 Rather than timing out after 20 ms if an EC
1958 command is not properly ACKed, override the length
1959 of the timeout. We have interrupts disabled while
1960 waiting for the ACK, so if this is set too high
1961 interrupts *may* be lost!
1962
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001963 omap_mux= [OMAP] Override bootloader pin multiplexing.
1964 Format: <mux_mode0.mode_name=value>...
1965 For example, to override I2C bus2:
1966 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1967
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 oprofile.timer= [HW]
1969 Use timer interrupt instead of performance counters
1970
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001971 oprofile.cpu_type= Force an oprofile cpu type
1972 This might be useful if you have an older oprofile
1973 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001974 Format: { arch_perfmon }
1975 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001976 perfmon on Intel CPUs instead of the
1977 CPU specific event set.
Robert Richter159a80b2011-10-11 19:39:16 +02001978 timer: [X86] Force use of architectural NMI
1979 timer mode (see also oprofile.timer
1980 for generic hr timer mode)
Andreas Krebbeldd3c4672011-11-25 20:03:05 +01001981 [s390] Force legacy basic mode sampling
1982 (report cpu_type "timer")
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001983
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001984 oops=panic Always panic on oopses. Default is to just kill the
1985 process, but there is a small probability of
1986 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07001987 This will also cause panics on machine check exceptions.
1988 Useful together with panic=30 to trigger a reboot.
1989
Randy Dunlapbcfde332010-06-07 17:10:38 -07001990 OSS [HW,OSS]
1991 See Documentation/sound/oss/oss-parameters.txt
1992
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001993 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07001994 timeout > 0: seconds before rebooting
1995 timeout = 0: wait forever
1996 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997 Format: <timeout>
1998
1999 parkbd.port= [HW] Parallel port number the keyboard adapter is
2000 connected to, default is 0.
2001 Format: <parport#>
2002 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2003 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07002004 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005
Randy Dunlapa9913042005-10-23 12:57:11 -07002006 parport= [HW,PPT] Specify parallel ports. 0 disables.
2007 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2008 Use 'auto' to force the driver to use any
2009 IRQ/DMA settings detected (the default is to
2010 ignore detected IRQ/DMA settings because of
2011 possible conflicts). You can specify the base
2012 address, IRQ, and DMA settings; IRQ and DMA
2013 should be numbers, or 'auto' (for using detected
2014 settings on that particular port), or 'nofifo'
2015 (to avoid using a FIFO even if it is detected).
2016 Parallel ports are assigned in the order they
2017 are specified on the command line, starting
2018 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019
Randy Dunlapa9913042005-10-23 12:57:11 -07002020 parport_init_mode= [HW,PPT]
2021 Configure VIA parallel port to operate in
2022 a specific mode. This is necessary on Pegasos
2023 computer where firmware has no options for setting
2024 up parallel port mode and sets it to spp.
2025 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 Format: [spp|ps2|epp|ecp|ecpepp]
2027
Andrew Mortondd287792006-03-23 03:00:57 -08002028 pause_on_oops=
2029 Halt all CPUs after the first oops has been printed for
2030 the specified number of seconds. This is to be used if
2031 your oopses keep scrolling off the screen.
2032
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 pcbit= [HW,ISDN]
2034
2035 pcd. [PARIDE]
2036 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002037 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038
Randy Dunlapa9913042005-10-23 12:57:11 -07002039 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07002040 earlydump [X86] dump PCI config space before the kernel
2041 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02002042 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002043 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07002044 the hardware directly. Use this if your machine
2045 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002046 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07002047 hardware access methods are allowed. Use this
2048 if you experience crashes upon bootup and you
2049 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002050 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002051 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02002052 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002053 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07002054 noaer [PCIE] If the PCIEAER kernel config parameter is
2055 enabled, this kernel boot option can be used to
2056 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04002057 nodomains [PCI] Disable support for multiple PCI
2058 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302059 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08002060 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02002061 check_enable_amd_mmconf [X86] check for and enable
2062 properly configured MMIO access to PCI
2063 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07002064 nomsi [MSI] If the PCI_MSI kernel config parameter is
2065 enabled, this kernel boot option can be used to
2066 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02002067 noioapicquirk [APIC] Disable all boot interrupt quirks.
2068 Safety option to keep boot IRQs enabled. This
2069 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02002070 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2071 primary IO-APIC for bridges that cannot disable
2072 boot IRQs. This fixes a source of spurious IRQs
2073 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02002074 noioapicreroute [APIC] Disable workaround that uses the
2075 boot IRQ equivalent of an IRQ that connects to
2076 a chipset where boot IRQs cannot be disabled.
2077 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002078 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07002079 routing table. These calls are known to be buggy
2080 on several machines and they hang the machine
2081 when used, but on other computers it's the only
2082 way to get the interrupt routing table. Try
2083 this option if the kernel is unable to allocate
2084 IRQs or discover secondary PCI buses on your
2085 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02002086 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07002087 Use with caution as certain devices share
2088 address decoders between ROMs and other
2089 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02002090 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07002091 expansion ROMs that do not already have
2092 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07002093 nobar [X86] Do not assign address space to the
2094 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002095 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002096 assigned automatically to PCI devices. You can
2097 make the kernel exclude IRQs of your ISA cards
2098 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002099 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002100 of the PIRQ table (normally generated
2101 by the BIOS) if it is outside the
2102 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002103 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002104 useful if the kernel is unable to find your
2105 secondary buses and you want to tell it
2106 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002107 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002108 numbers ourselves, overriding
2109 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002110 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002111 in the BIOS $PIR table. This is needed on
2112 some systems with broken BIOSes, notably
2113 some HP Pavilion N5400 and Omnibook XE3
2114 notebooks. This will have no effect if ACPI
2115 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002116 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002117 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002118 use_crs [X86] Use PCI host bridge window information
2119 from ACPI. On BIOSes from 2008 or later, this
2120 is enabled by default. If you need to use this,
2121 please report a bug.
2122 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2123 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002124 routeirq Do IRQ routing for all PCI devices.
2125 This is normally done in pci_enable_device(),
2126 so this option is a temporary workaround
2127 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002128 skip_isa_align [X86] do not align io start addr, so can
2129 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002130 firmware [ARM] Do not re-enumerate the bus but instead
2131 just use the configuration from the
2132 bootloader. This is currently used on
2133 IXP2000 systems where the bus has to be
2134 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002135 noearly [X86] Don't do any early type 1 scanning.
2136 This might help on some broken boards which
2137 machine check when some devices' config space
2138 is read. But various workarounds are disabled
2139 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002140 bfsort Sort PCI devices into breadth-first order.
2141 This sorting is done to get a device
2142 order compatible with older (<= 2.4) kernels.
2143 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002144 cbiosize=nn[KMG] The fixed amount of bus space which is
2145 reserved for the CardBus bridge's IO window.
2146 The default value is 256 bytes.
2147 cbmemsize=nn[KMG] The fixed amount of bus space which is
2148 reserved for the CardBus bridge's memory
2149 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09002150 resource_alignment=
2151 Format:
2152 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2153 Specifies alignment and device to reassign
2154 aligned memory resources.
2155 If <order of align> is not specified,
2156 PAGE_SIZE is used as alignment.
2157 PCI-PCI bridge can be specified, if resource
2158 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002159 ecrc= Enable/disable PCIe ECRC (transaction layer
2160 end-to-end CRC checking).
2161 bios: Use BIOS/firmware settings. This is the
2162 the default.
2163 off: Turn ECRC off
2164 on: Turn ECRC on.
Yinghai Lub55438f2012-02-23 19:23:30 -08002165 realloc= Enable/disable reallocating PCI bridge resources
2166 if allocations done by BIOS are too small to
2167 accommodate resources required by all child
2168 devices.
2169 off: Turn realloc off
2170 on: Turn realloc on
2171 realloc same as realloc=on
Rafael J. Wysocki6748dcc2012-03-01 00:06:33 +01002172 noari do not use PCIe ARI.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002173
Chuck Ebberte5665a42008-09-24 20:40:34 -04002174 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2175 Management.
2176 off Disable ASPM.
2177 force Enable ASPM even on devices that claim not to support it.
2178 WARNING: Forcing ASPM on may cause system lockups.
2179
MUNEDA Takahiro7570a332012-02-02 11:09:22 -05002180 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2181 nomsi Do not use MSI for PCI Express Native Hotplug (this
2182 makes all PCIe ports use INTx for hotplug services).
2183
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002184 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002185 auto Ask the BIOS whether or not to use native PCIe services
2186 associated with PCIe ports (PME, hot-plug, AER). Use
2187 them only if that is allowed by the BIOS.
2188 native Use native PCIe services associated with PCIe ports
2189 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002190 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2191 ports driver.
2192
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002193 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002194 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002195 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002196
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 pcmv= [HW,PCMCIA] BadgePAD 4
2198
2199 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002200 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201
2202 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2203 boot time.
2204 Format: { 0 | 1 }
2205 See arch/parisc/kernel/pdc_chassis.c
2206
Tejun Heof58dc012009-08-14 15:00:50 +09002207 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002208 Currently supported values are "embed" and "page".
2209 Archs may support subset or none of the selections.
2210 See comments in mm/percpu.c for details on each
2211 allocator. This parameter is primarily for debugging
2212 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002213
Linus Torvalds1da177e2005-04-16 15:20:36 -07002214 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002215 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216
2217 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002218 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219
2220 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002221 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222
2223 plip= [PPT,NET] Parallel port network link
2224 Format: { parport<nr> | timid | 0 }
2225 See also Documentation/parport.txt.
2226
Randy Dunlap16290242011-08-13 12:34:52 -07002227 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002228 Override pmtimer IOPort with a hex value.
2229 e.g. pmtmr=0x508
2230
Bjorn Helgaas96242112011-08-11 12:14:05 -06002231 pnp.debug=1 [PNP]
2232 Enable PNP debug messages (depends on the
2233 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2234 via /sys/module/pnp/parameters/debug. We always show
2235 current resource usage; turning this on also shows
2236 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002237
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 pnpacpi= [ACPI]
2239 { off }
2240
2241 pnpbios= [ISAPNP]
2242 { on | off | curr | res | no-curr | no-res }
2243
2244 pnp_reserve_irq=
2245 [ISAPNP] Exclude IRQs for the autoconfiguration
2246
2247 pnp_reserve_dma=
2248 [ISAPNP] Exclude DMAs for the autoconfiguration
2249
2250 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002251 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252
2253 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002254 [ISAPNP] Exclude memory regions for the
2255 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 Ranges are in pairs (memory base and size).
2257
Randy Dunlap4af94f32009-04-17 18:30:28 -07002258 ports= [IP_VS_FTP] IPVS ftp helper module
2259 Default is 21.
2260 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2261 may be specified.
2262 Format: <port>,<port>....
2263
Ingo Molnar45807a12007-07-15 23:40:10 -07002264 print-fatal-signals=
2265 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002266
2267 If enabled, warn about various signal handling
2268 related application anomalies: too many signals,
2269 too many POSIX.1 timers, fatal signals causing a
2270 coredump - etc.
2271
2272 If you hit the warning due to signal overflow,
2273 you might want to try "ulimit -i unlimited".
2274
Ingo Molnar45807a12007-07-15 23:40:10 -07002275 default: off.
2276
Matthew Garrettc22ab332012-03-05 14:59:10 -08002277 printk.always_kmsg_dump=
2278 Trigger kmsg_dump for cases other than kernel oops or
2279 panics
2280 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2281 default: disabled
2282
Randy Dunlape84845c2007-07-15 23:40:25 -07002283 printk.time= Show timing data prefixed to each printk message line
2284 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2285
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002286 processor.max_cstate= [HW,ACPI]
2287 Limit processor to maximum C-state
2288 max_cstate=9 overrides any DMI blacklist limit.
2289
2290 processor.nocst [HW,ACPI]
2291 Ignore the _CST method to determine C-states,
2292 instead using the legacy FADT method
2293
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002295 Format: [schedule,]<number>
2296 Param: "schedule" - profile schedule points.
2297 Param: <number> - step/bucket size as a power of 2 for
2298 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002299 Param: "sleep" - profile D-state sleeping (millisecs).
2300 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002301 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302
Linus Torvalds1da177e2005-04-16 15:20:36 -07002303 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2304 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002305 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306
Randy Dunlapa9913042005-10-23 12:57:11 -07002307 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2308 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002309 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2310 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002311 psmouse.resetafter= [HW,MOUSE]
2312 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313 (0 = never).
2314 psmouse.resolution=
2315 [HW,MOUSE] Set desired mouse resolution, in dpi.
2316 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002317 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 0 = disabled, 1 = enabled (default).
2319
Matthew Garrettdee28e72011-07-21 16:57:55 -04002320 pstore.backend= Specify the name of the pstore backend to use
2321
Linus Torvalds1da177e2005-04-16 15:20:36 -07002322 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002323 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324
Kay Sieversdc8c8582007-08-15 12:25:38 +02002325 pty.legacy_count=
2326 [KNL] Number of legacy pty's. Overwrites compiled-in
2327 default number.
2328
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002329 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002330
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331 r128= [HW,DRM]
2332
2333 raid= [HW,RAID]
2334 See Documentation/md.txt.
2335
Randy Dunlapa9913042005-10-23 12:57:11 -07002336 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002337 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002338
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002340 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002341
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002342 rcupdate.blimit= [KNL,BOOT]
2343 Set maximum number of finished RCU callbacks to process
2344 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002345
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002346 rcupdate.qhimark= [KNL,BOOT]
2347 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002348 RCU callbacks over which batch limiting is disabled.
2349
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002350 rcupdate.qlowmark= [KNL,BOOT]
2351 Set threshold of queued RCU callbacks below which
2352 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002353
Olof Johanssonffdfc402005-09-06 15:17:19 -07002354 rdinit= [KNL]
2355 Format: <full_path>
2356 Run specified binary instead of /init from the ramdisk,
2357 used for early userspace startup. See initrd.
2358
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002359 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002361 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362
Paul Jackson46b6d942008-07-04 10:00:09 -07002363 relax_domain_level=
2364 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002365 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002366
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2368
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002369 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002370 Format: nn[KMG]
2371 Reserves a hole at the top of the kernel virtual
2372 address space.
2373
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002374 reservelow= [X86]
2375 Format: nn[K]
2376 Set the amount of memory to reserve for BIOS at
2377 the bottom of the address space.
2378
Vivek Goyal7e962872006-09-27 01:50:44 -07002379 reset_devices [KNL] Force drivers to reset the underlying device
2380 during initialization.
2381
Randy Dunlapa9913042005-10-23 12:57:11 -07002382 resume= [SWSUSP]
2383 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002385 resume_offset= [SWSUSP]
2386 Specify the offset from the beginning of the partition
2387 given by "resume=" at which the swap header is located,
2388 in <PAGE_SIZE> units (needed only for swap files).
2389 See Documentation/power/swsusp-and-swap-files.txt
2390
Barry Songf126f732011-10-10 23:38:41 +02002391 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2392 read the resume files
2393
Barry Song6f8d7022011-10-06 20:34:46 +02002394 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2395 Useful for devices that are detected asynchronously
2396 (e.g. USB and MMC devices).
2397
Bojan Smojverf996fc92010-09-09 23:06:23 +02002398 hibernate= [HIBERNATION]
2399 noresume Don't check if there's a hibernation image
2400 present during boot.
2401 nocompress Don't compress/decompress hibernation images.
2402
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002403 retain_initrd [RAM] Keep initrd memory after extraction
2404
Linus Torvalds1da177e2005-04-16 15:20:36 -07002405 rhash_entries= [KNL,NET]
2406 Set number of hash buckets for route cache
2407
2408 riscom8= [HW,SERIAL]
2409 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2410
2411 ro [KNL] Mount root device read-only on boot
2412
2413 root= [KNL] Root filesystem
Will Drewryf2d34fd2011-08-03 16:21:08 -07002414 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415
2416 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2417 mount the root filesystem
2418
2419 rootflags= [KNL] Set root filesystem mount option string
2420
2421 rootfstype= [KNL] Set root filesystem type
2422
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002423 rootwait [KNL] Wait (indefinitely) for root device to show up.
2424 Useful for devices that are detected asynchronously
2425 (e.g. USB and MMC devices).
2426
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 rw [KNL] Mount root device read-write on boot
2428
2429 S [KNL] Run init in single mode
2430
2431 sa1100ir [NET]
2432 See drivers/net/irda/sa1100_ir.c.
2433
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002435
Mike Travisf6630112009-11-17 18:22:15 -06002436 sched_debug [KNL] Enables verbose scheduler debug messages.
2437
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002438 security= [SECURITY] Choose a security module to enable at boot.
2439 If this boot parameter is not specified, only the first
2440 security module asking for security registration will be
2441 loaded. An invalid security module name will be treated
2442 as if no module has been chosen.
2443
2444 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 Format: { "0" | "1" }
2446 See security/selinux/Kconfig help text.
2447 0 -- disable.
2448 1 -- enable.
2449 Default value is set via kernel config option.
2450 If enabled at boot time, /selinux/disable can be used
2451 later to disable prior to initial policy load.
2452
John Johansenc1c124e2010-07-29 14:48:09 -07002453 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2454 Format: { "0" | "1" }
2455 See security/apparmor/Kconfig help text
2456 0 -- disable.
2457 1 -- enable.
2458 Default value is set via kernel config option.
2459
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002460 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461
Linus Torvalds1da177e2005-04-16 15:20:36 -07002462 shapers= [NET]
2463 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002464
Yinghai Lub05f78f2008-08-22 01:32:50 -07002465 show_msr= [x86] show boot-time MSR settings
2466 Format: { <integer> }
2467 Show boot-time (BIOS-initialized) MSR settings.
2468 The parameter means the number of CPUs to show,
2469 for example 1 means boot CPU only.
2470
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 simeth= [IA-64]
2472 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002473
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 slram= [HW,MTD]
2475
David Rientjes3df1ccc2011-10-18 22:09:28 -07002476 slab_max_order= [MM, SLAB]
2477 Determines the maximum allowed order for slabs.
2478 A high setting may cause OOMs due to memory
2479 fragmentation. Defaults to 1 for systems with
2480 more than 32MB of RAM, 0 otherwise.
2481
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002482 slub_debug[=options[,slabs]] [MM, SLUB]
2483 Enabling slub_debug allows one to determine the
2484 culprit if slab objects become corrupted. Enabling
2485 slub_debug can create guard zones around objects and
2486 may poison objects when not in use. Also tracks the
2487 last alloc / free. For more information see
2488 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002489
2490 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002491 Determines the maximum allowed order for slabs.
2492 A high setting may cause OOMs due to memory
2493 fragmentation. For more information see
2494 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002495
2496 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002497 The minimum number of objects per slab. SLUB will
2498 increase the slab order up to slub_max_order to
2499 generate a sufficiently large slab able to contain
2500 the number of objects indicated. The higher the number
2501 of objects the smaller the overhead of tracking slabs
2502 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002503 For more information see Documentation/vm/slub.txt.
2504
2505 slub_min_order= [MM, SLUB]
Masanari Iida24775d62012-02-15 00:26:42 +09002506 Determines the minimum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002507 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002508 For more information see Documentation/vm/slub.txt.
2509
2510 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002511 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002512 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002513 allocs to different slabs. Debug options disable
2514 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002515 For more information see Documentation/vm/slub.txt.
2516
Linus Torvalds1da177e2005-04-16 15:20:36 -07002517 smart2= [HW]
2518 Format: <io1>[,<io2>[,...,<io8>]]
2519
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002520 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002521 attempt to substitute SMP alternatives once at boot.
2522
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002523 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2524 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2525 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2526 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2527 smsc-ircc2.ircc_irq= [HW] IRQ line
2528 smsc-ircc2.ircc_dma= [HW] DMA channel
2529 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2530 0: Toshiba Satellite 1800 (GP data pin select)
2531 1: Fast pin select (default)
2532 2: ATC IRMode
2533
Bryan Huntsman3f2bc4d2011-08-16 17:27:22 -07002534 snddev_icodec.msm_codec_i2s_slave_mode= [ARM-MSM]
2535 1, codec is I2S master
2536 0, MSM is I2S master (default)
2537
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002538 softlockup_panic=
2539 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002540 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002541
Linus Torvalds1da177e2005-04-16 15:20:36 -07002542 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02002543 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544
2545 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002546 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002547
2548 spia_io_base= [HW,MTD]
2549 spia_fio_base=
2550 spia_pedr=
2551 spia_peddr=
2552
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002553 stacktrace [FTRACE]
2554 Enabled the stack tracer on boot up.
2555
Steven Rostedt762e1202011-12-19 22:01:00 -05002556 stacktrace_filter=[function-list]
2557 [FTRACE] Limit the functions that the stack tracer
2558 will trace at boot up. function-list is a comma separated
2559 list of functions. This list can be changed at run
2560 time by the stack_trace_filter file in the debugfs
2561 tracing directory. Note, this enables stack tracing
2562 and the stacktrace above is not needed.
2563
Linus Torvalds1da177e2005-04-16 15:20:36 -07002564 sti= [PARISC,HW]
2565 Format: <num>
2566 Set the STI (builtin display/keyboard on the HP-PARISC
2567 machines) console (graphic card) which should be used
2568 as the initial boot-console.
2569 See also comment in drivers/video/console/sticore.c.
2570
2571 sti_font= [HW]
2572 See comment in drivers/video/console/sticore.c.
2573
2574 stifb= [HW]
2575 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2576
Trond Myklebustcbf11072009-08-09 15:06:19 -04002577 sunrpc.min_resvport=
2578 sunrpc.max_resvport=
2579 [NFS,SUNRPC]
2580 SunRPC servers often require that client requests
2581 originate from a privileged port (i.e. a port in the
2582 range 0 < portnr < 1024).
2583 An administrator who wishes to reserve some of these
2584 ports for other uses may adjust the range that the
2585 kernel's sunrpc client considers to be privileged
2586 using these two parameters to set the minimum and
2587 maximum port values.
2588
Greg Banks42a7fc42007-03-06 01:42:23 -08002589 sunrpc.pool_mode=
2590 [NFS]
2591 Control how the NFS server code allocates CPUs to
2592 service thread pools. Depending on how many NICs
2593 you have and where their interrupts are bound, this
2594 option will affect which CPUs will do NFS serving.
2595 Note: this parameter cannot be changed while the
2596 NFS server is running.
2597
2598 auto the server chooses an appropriate mode
2599 automatically using heuristics
2600 global a single global pool contains all CPUs
2601 percpu one pool for each CPU
2602 pernode one pool for each NUMA node (equivalent
2603 to global on non-NUMA machines)
2604
Trond Myklebustcbf11072009-08-09 15:06:19 -04002605 sunrpc.tcp_slot_table_entries=
2606 sunrpc.udp_slot_table_entries=
2607 [NFS,SUNRPC]
2608 Sets the upper limit on the number of simultaneous
2609 RPC calls that can be sent from the client to a
2610 server. Increasing these values may allow you to
2611 improve throughput, but will also increase the
2612 amount of memory reserved for use by the client.
2613
Michal Hockoa42c3902010-11-24 12:57:08 -08002614 swapaccount[=0|1]
2615 [KNL] Enable accounting of swap in memory resource
2616 controller if no parameter or 1 is given or disable
2617 it if 0 is given (See Documentation/cgroups/memory.txt)
2618
Linus Torvalds1da177e2005-04-16 15:20:36 -07002619 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002620
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621 switches= [HW,M68k]
2622
Andi Kleene52eec12010-09-08 16:54:17 +02002623 sysfs.deprecated=0|1 [KNL]
2624 Enable/disable old style sysfs layout for old udev
2625 on older distributions. When this option is enabled
2626 very new udev will not work anymore. When this option
2627 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2628 in older udev will not work anymore.
2629 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2630 the kernel configuration.
2631
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002632 sysrq_always_enabled
2633 [KNL]
2634 Ignore sysrq setting - this boot parameter will
2635 neutralize any effect of /proc/sys/kernel/sysrq.
2636 Useful for debugging.
2637
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638 tdfx= [HW,DRM]
2639
David Brownell77437fd2008-07-23 21:28:33 -07002640 test_suspend= [SUSPEND]
2641 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2642 standby suspend) as the system sleep state to briefly
2643 enter during system startup. The system is woken from
2644 this state using a wakeup-capable RTC alarm.
2645
Linus Torvalds1da177e2005-04-16 15:20:36 -07002646 thash_entries= [KNL,NET]
2647 Set number of hash buckets for TCP connection
2648
Len Brownf8707ec2007-08-12 00:12:54 -04002649 thermal.act= [HW,ACPI]
2650 -1: disable all active trip points in all thermal zones
2651 <degrees C>: override all lowest active trip points
2652
Len Brownc52a7412007-08-14 15:49:32 -04002653 thermal.crt= [HW,ACPI]
2654 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002655 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002656
Len Brownf5487142007-08-12 00:12:44 -04002657 thermal.nocrt= [HW,ACPI]
2658 Set to disable actions on ACPI thermal zone
2659 critical and hot trip points.
2660
Len Brown72b33ef2007-08-12 00:12:17 -04002661 thermal.off= [HW,ACPI]
2662 1: disable ACPI thermal control
2663
Len Browna70cdc52007-08-12 00:12:35 -04002664 thermal.psv= [HW,ACPI]
2665 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002666 <degrees C>: override all passive trip points to this
2667 value
Len Browna70cdc52007-08-12 00:12:35 -04002668
Len Brown730ff342007-08-12 00:12:26 -04002669 thermal.tzp= [HW,ACPI]
2670 Specify global default ACPI thermal zone polling rate
2671 <deci-seconds>: poll all this frequency
2672 0: no polling (default)
2673
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002674 threadirqs [KNL]
2675 Force threading of all interrupt handlers except those
Masanari Iida24775d62012-02-15 00:26:42 +09002676 marked explicitly IRQF_NO_THREAD.
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002677
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002678 topology= [S390]
2679 Format: {off | on}
2680 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002681 topology information if the hardware supports this.
2682 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002683 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002684 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002685
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 tp720= [HW,PS2]
2687
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002688 tpm_suspend_pcr=[HW,TPM]
2689 Format: integer pcr id
2690 Specify that at suspend time, the tpm driver
2691 should extend the specified pcr with zeros,
2692 as a workaround for some chips which fail to
2693 flush the last written pcr on TPM_SaveState.
2694 This will guarantee that all the other pcrs
2695 are saved.
2696
Li Zefan9d612be2009-06-24 17:33:15 +08002697 trace_buf_size=nn[KMG]
2698 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002699
Li Zefan020e5f82009-07-01 10:47:05 +08002700 trace_event=[event-list]
2701 [FTRACE] Set and start specified trace events in order
2702 to facilitate early boot debugging.
2703 See also Documentation/trace/events.txt
2704
Jiri Kosinafcf4d822012-03-21 16:34:02 -07002705 transparent_hugepage=
2706 [KNL]
2707 Format: [always|madvise|never]
2708 Can be used to control the default behavior of the system
2709 with respect to transparent hugepages.
2710 See Documentation/vm/transhuge.txt for more details.
2711
john stultzd3b8f882009-08-17 16:40:47 -07002712 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002713 Format: <string>
2714 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002715 disables clocksource verification at runtime, as well
2716 as the stability checks done at bootup. Used to enable
2717 high-resolution timer mode on older hardware, and in
2718 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002719 [x86] noirqtime: Do not use TSC to do irq accounting.
2720 Used to run time disable IRQ_TIME_ACCOUNTING on any
2721 platforms where RDTSC is slow and this accounting
2722 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002723
Randy Dunlapa9913042005-10-23 12:57:11 -07002724 turbografx.map[2|3]= [HW,JOY]
2725 TurboGraFX parallel port interface
2726 Format:
2727 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728 See also Documentation/input/joystick-parport.txt
2729
Christian Kujaub6935f82011-05-31 15:22:05 +00002730 udbg-immortal [PPC] When debugging early kernel crashes that
2731 happen after console_init() and before a proper
2732 console driver takes over, this boot options might
2733 help "seeing" what's going on.
2734
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002735 uhash_entries= [KNL,NET]
2736 Set number of hash buckets for UDP/UDP-Lite connections
2737
Alan Stern5f8364b2006-12-05 16:29:55 -05002738 uhci-hcd.ignore_oc=
2739 [USB] Ignore overcurrent events (default N).
2740 Some badly-designed motherboards generate lots of
2741 bogus events, for ports that aren't wired to
2742 anything. Set this parameter to avoid log spamming.
2743 Note that genuine overcurrent events won't be
2744 reported either.
2745
Simon Arlotte3a61b02008-07-19 23:32:54 +01002746 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002747 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01002748
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02002749 usbcore.authorized_default=
2750 [USB] Default USB device authorization:
2751 (default -1 = authorized except for wireless USB,
2752 0 = not authorized, 1 = authorized)
2753
Alan Sternb5e795f2007-02-20 15:00:53 -05002754 usbcore.autosuspend=
2755 [USB] The autosuspend time delay (in seconds) used
2756 for newly-detected USB devices (default 2). This
2757 is the time required before an idle device will be
2758 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002759 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002760
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002761 usbcore.usbfs_snoop=
2762 [USB] Set to log all usbfs traffic (default 0 = off).
2763
2764 usbcore.blinkenlights=
2765 [USB] Set to cycle leds on hubs (default 0 = off).
2766
2767 usbcore.old_scheme_first=
2768 [USB] Start with the old device initialization
2769 scheme (default 0 = off).
2770
Alan Stern3f5eb8d2011-11-17 16:41:35 -05002771 usbcore.usbfs_memory_mb=
2772 [USB] Memory limit (in MB) for buffers allocated by
2773 usbfs (default = 16, 0 = max = 2047).
2774
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002775 usbcore.use_both_schemes=
2776 [USB] Try the other device initialization scheme
2777 if the first one fails (default 1 = enabled).
2778
2779 usbcore.initial_descriptor_timeout=
2780 [USB] Specifies timeout for the initial 64-byte
2781 USB_REQ_GET_DESCRIPTOR request in milliseconds
2782 (default 5000 = 5.0 seconds).
2783
Linus Torvalds1da177e2005-04-16 15:20:36 -07002784 usbhid.mousepoll=
2785 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002786
Alan Sternd4f373e2008-11-10 14:07:45 -05002787 usb-storage.delay_use=
2788 [UMS] The delay in seconds before a new device is
2789 scanned for Logical Units (default 5).
2790
2791 usb-storage.quirks=
2792 [UMS] A list of quirks entries to supplement or
2793 override the built-in unusual_devs list. List
2794 entries are separated by commas. Each entry has
2795 the form VID:PID:Flags where VID and PID are Vendor
2796 and Product ID values (4-digit hex numbers) and
2797 Flags is a set of characters, each corresponding
2798 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002799 a = SANE_SENSE (collect more than 18 bytes
2800 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002801 b = BAD_SENSE (don't collect more than 18
2802 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002803 c = FIX_CAPACITY (decrease the reported
2804 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01002805 d = NO_READ_DISC_INFO (don't use
2806 READ_DISC_INFO command);
2807 e = NO_READ_CAPACITY_16 (don't use
2808 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05002809 h = CAPACITY_HEURISTICS (decrease the
2810 reported device capacity by one
2811 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002812 i = IGNORE_DEVICE (don't bind to this
2813 device);
2814 l = NOT_LOCKABLE (don't try to lock and
2815 unlock ejectable media);
2816 m = MAX_SECTORS_64 (don't transfer more
2817 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04002818 n = INITIAL_READ10 (force a retry of the
2819 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05002820 o = CAPACITY_OK (accept the capacity
2821 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002822 r = IGNORE_RESIDUE (the device reports
2823 bogus residue values);
2824 s = SINGLE_LUN (the device has only one
2825 Logical Unit);
2826 w = NO_WP_DETECT (don't test whether the
2827 medium is write-protected).
2828 Example: quirks=0419:aaf5:rl,0421:0433:rc
2829
Stephen Boydac1667d2011-08-13 12:34:50 -07002830 user_debug= [KNL,ARM]
2831 Format: <int>
2832 See arch/arm/Kconfig.debug help text.
2833 1 - undefined instruction events
2834 2 - system calls
2835 4 - invalid data aborts
2836 8 - SIGSEGV faults
2837 16 - SIGBUS faults
2838 Example: user_debug=31
2839
Ian Campbell14315592010-02-17 10:38:10 +00002840 userpte=
2841 [X86] Flags controlling user PTE allocations.
2842
2843 nohigh = do not allocate PTE pages in
2844 HIGHMEM regardless of setting
2845 of CONFIG_HIGHPTE.
2846
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302847 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002848 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002849 vdso=1: enable VDSO (default)
2850 vdso=0: disable VDSO mapping
2851
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302852 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002853 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2854 vdso32=1: enable 32-bit VDSO (default)
2855 vdso32=0: disable 32-bit VDSO mapping
2856
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002857 vector= [IA-64,SMP]
2858 vector=percpu: enable percpu vector domain
2859
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860 video= [FB] Frame buffer configuration
2861 See Documentation/fb/modedb.txt.
2862
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002863 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002864 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002865 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002866 Use vga=ask for menu.
2867 This is actually a boot loader parameter; the value is
2868 passed to the kernel using a special protocol.
2869
Randy Dunlapa9913042005-10-23 12:57:11 -07002870 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871 size of <nn>. This can be used to increase the
2872 minimum size (128MB on x86). It can also be used to
2873 decrease the size and leave more room for directly
2874 mapped kernel RAM.
2875
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002876 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2877 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002878
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002879 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2880 Format: <command>
2881
2882 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2883 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002884
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002885 vsyscall= [X86-64]
2886 Controls the behavior of vsyscalls (i.e. calls to
2887 fixed addresses of 0xffffffffff600x00 from legacy
2888 code). Most statically-linked binaries and older
2889 versions of glibc use these calls. Because these
2890 functions are at fixed addresses, they make nice
2891 targets for exploits that can control RIP.
2892
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08002893 emulate [default] Vsyscalls turn into traps and are
2894 emulated reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002895
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08002896 native Vsyscalls are native syscall instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002897 This is a little bit faster than trapping
2898 and makes a few dynamic recompilers work
2899 better than they would in emulation mode.
2900 It also makes exploits much easier to write.
2901
2902 none Vsyscalls don't work at all. This makes
2903 them quite hard to use for exploits but
2904 might break your system.
2905
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002906 vt.cur_default= [VT] Default cursor shape.
2907 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2908 the parameters of the <Esc>[?A;B;Cc escape sequence;
2909 see VGA-softcursor.txt. Default: 2 = underline.
2910
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002911 vt.default_blu= [VT]
2912 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2913 Change the default blue palette of the console.
2914 This is a 16-member array composed of values
2915 ranging from 0-255.
2916
2917 vt.default_grn= [VT]
2918 Format: <green0>,<green1>,<green2>,...,<green15>
2919 Change the default green palette of the console.
2920 This is a 16-member array composed of values
2921 ranging from 0-255.
2922
2923 vt.default_red= [VT]
2924 Format: <red0>,<red1>,<red2>,...,<red15>
2925 Change the default red palette of the console.
2926 This is a 16-member array composed of values
2927 ranging from 0-255.
2928
2929 vt.default_utf8=
2930 [VT]
2931 Format=<0|1>
2932 Set system-wide default UTF-8 mode for all tty's.
2933 Default is 1, i.e. UTF-8 mode is enabled for all
2934 newly opened terminals.
2935
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002936 vt.global_cursor_default=
2937 [VT]
2938 Format=<-1|0|1>
2939 Set system-wide default for whether a cursor
2940 is shown on new VTs. Default is -1,
2941 i.e. cursors will be created by default unless
2942 overridden by individual drivers. 0 will hide
2943 cursors, 1 will display them.
2944
Randy Dunlap4724ba52010-05-03 11:42:52 -07002945 watchdog timers [HW,WDT] For information on watchdog timers,
2946 see Documentation/watchdog/watchdog-parameters.txt
2947 or other driver-specific files in the
2948 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002949
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002950 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2951 default x2apic cluster mode on platforms
2952 supporting x2apic.
2953
Jacob Panbb24c472009-09-02 07:37:17 -07002954 x86_mrst_timer= [X86-32,APBT]
2955 Choose timer option for x86 Moorestown MID platform.
2956 Two valid options are apbt timer only and lapic timer
2957 plus one apbt timer for broadcast timer.
2958 x86_mrst_timer=apbt_only | lapic_and_apbt
2959
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2961 xd_geo= See header of drivers/block/xd.c.
2962
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002963 xen_emul_unplug= [HW,X86,XEN]
2964 Unplug Xen emulated devices
2965 Format: [unplug0,][unplug1]
2966 ide-disks -- unplug primary master IDE devices
2967 aux-ide-disks -- unplug non-primary-master IDE devices
2968 nics -- unplug network devices
2969 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002970 unnecessary -- unplugging emulated devices is
2971 unnecessary even if the host did not respond to
2972 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002973 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002974
Linus Torvalds1da177e2005-04-16 15:20:36 -07002975 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002976 Format:
2977 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978
Randy Dunlapa9913042005-10-23 12:57:11 -07002979______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002980
2981TODO:
2982
Linus Torvalds1da177e2005-04-16 15:20:36 -07002983 Add more DRM drivers.