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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
Robert Jennings14f966e2009-04-15 05:55:32 +0000511 cmo_free_hint= [PPC] Format: { yes | no }
512 Specify whether pages are marked as being inactive
513 when they are freed. This is used in CMO environments
514 to determine OS memory pressure for page stealing by
515 a hypervisor.
516 Default: yes
517
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530518 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100519 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100520 Range: 0 - 8192
521 Default: 64
522
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700524 Format:
525 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526
527 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
528 Format: <io>[,<irq>]
529
Randy Dunlapa9913042005-10-23 12:57:11 -0700530 com90xx= [HW,NET]
531 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 Format: <io>[,<irq>[,<memstart>]]
533
534 condev= [HW,S390] console device
535 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700536
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 console= [KNL] Output console device and options.
538
539 tty<n> Use the virtual console device <n>.
540
541 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800542 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800544 the form "bbbbpnf", where "bbbb" is the baud rate,
545 "p" is parity ("n", "o", or "e"), "n" is number of
546 bits, and "f" is flow control ("r" for RTS or
547 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800549 See Documentation/serial-console.txt for more
550 information. See
551 Documentation/networking/netconsole.txt for an
552 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700554 uart[8250],io,<addr>[,options]
555 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 Start an early, polled-mode console on the 8250/16550
557 UART at the specified I/O port or MMIO address,
558 switching to the matching ttyS device later. The
559 options are the same as for ttyS, above.
560
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700561 If the device connected to the port is not a TTY but a braille
562 device, prepend "brl," before the device type, for instance
563 console=brl,ttyS0
564 For now, only VisioBraille is supported.
565
Daniel Mackf324edc2009-06-16 15:33:52 -0700566 consoleblank= [KNL] The console blank (screen saver) timeout in
567 seconds. Defaults to 10*60 = 10mins. A value of 0
568 disables the blank timer.
569
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800570 coredump_filter=
571 [KNL] Change the default value for
572 /proc/<pid>/coredump_filter.
573 See also Documentation/filesystems/proc.txt.
574
Len Brown62027ae2011-04-01 18:13:10 -0400575 cpuidle.off=1 [CPU_IDLE]
576 disable the cpuidle sub-system
577
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700579 Format:
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800582 crashkernel=size[KMG][@offset[KMG]]
583 [KNL] Using kexec, Linux can switch to a 'crash kernel'
584 upon panic. This parameter reserves the physical
585 memory region [offset, offset + size] for that kernel
586 image. If '@offset' is omitted, then a suitable offset
587 is selected automatically. Check
588 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700589
Bernhard Wallefb391592007-10-18 23:41:02 -0700590 crashkernel=range1:size1[,range2:size2,...][@offset]
591 [KNL] Same as above, but depends on the memory
592 in the running system. The syntax of range is
593 start-[end] where start and end are both
594 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800595 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700596
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 cs89x0_dma= [HW,NET]
598 Format: <dma>
599
600 cs89x0_media= [HW,NET]
601 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700602
Randy Dunlapa9913042005-10-23 12:57:11 -0700603 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 See header of drivers/s390/block/dasd_devmap.c.
605
606 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
607 (one device per port)
608 Format: <port#>,<type>
609 See also Documentation/input/joystick-parport.txt
610
Thomas Renningera648ec02010-08-06 16:11:02 +0200611 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
612 time. See Documentation/dynamic-debug-howto.txt for
613 details.
614
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 debug [KNL] Enable kernel debugging (events log level).
616
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700617 debug_locks_verbose=
618 [KNL] verbose self-tests
619 Format=<0|1>
620 Print debugging info while doing the locking API
621 self-tests.
622 We default to 0 (no extra messages), setting it to
623 1 will print _a lot_ more information - normally
624 only useful to kernel developers.
625
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700626 debug_objects [KNL] Enable object debugging
627
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500628 no_debug_objects
629 [KNL] Disable object debugging
630
Stanislaw Gruszkac0a32fc2012-01-10 15:07:28 -0800631 debug_guardpage_minorder=
632 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
633 parameter allows control of the order of pages that will
634 be intentionally kept free (and hence protected) by the
635 buddy allocator. Bigger value increase the probability
636 of catching random memory corruption, but reduce the
637 amount of memory for normal system use. The maximum
638 possible value is MAX_ORDER/2. Setting this parameter
639 to 1 or 2 should be enough to identify most random
640 memory corruption problems caused by bugs in kernel or
641 driver code when a CPU writes to (or reads from) a
642 random memory location. Note that there exists a class
643 of memory corruptions problems caused by buggy H/W or
644 F/W or by drivers badly programing DMA (basically when
645 memory is written at bus level and the CPU MMU is
646 bypassed) which are not detectable by
647 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
648 tracking down these problems.
649
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200650 debugpat [X86] Enable PAT debugging
651
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200652 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 Format: <area>[,<node>]
654 See also Documentation/networking/decnet.txt.
655
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700656 default_hugepagesz=
657 [same as hugepagesz=] The size of the default
658 HugeTLB page size. This is the size represented by
659 the legacy /proc/ hugepages APIs, used for SHM, and
660 default size when mounting hugetlbfs filesystems.
661 Defaults to the default architecture's huge page size
662 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700663
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 dhash_entries= [KNL]
665 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700666
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 digi= [HW,SERIAL]
668 IO parameters + enable/disable command.
669
670 digiepca= [HW,SERIAL]
671 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000672 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673
Brian Haleyb0f83b22010-02-04 13:36:50 -0800674 disable= [IPV6]
675 See Documentation/networking/ipv6.txt.
676
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000677 disable_ddw [PPC/PSERIES]
678 Disable Dynamic DMA Window support. Use this if
679 to workaround buggy firmware.
680
Brian Haleyb0f83b22010-02-04 13:36:50 -0800681 disable_ipv6= [IPV6]
682 See Documentation/networking/ipv6.txt.
683
Yinghai Lu95ffa242008-04-29 03:52:33 -0700684 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700685 The kernel tries to adjust MTRR layout from continuous
686 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700687 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700688
Yinghai Lu093af8d2008-01-30 13:33:32 +0100689 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100690 By default the kernel will trim any uncacheable
691 memory out of your available memory pool based on
692 MTRR settings. This parameter disables that behavior,
693 possibly causing your machine to run very slowly.
694
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530695 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700696 Disable PIN 1 of APIC timer
697 Can be useful to work around chipset bugs.
698
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700699 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
700 this option disables the debugging code at boot.
701
702 dma_debug_entries=<number>
703 This option allows to tune the number of preallocated
704 entries for DMA-API debugging code. One entry is
705 required per DMA-API allocation. Use this if the
706 DMA-API debugging code disables itself because the
707 architectural default is too low.
708
Joerg Roedel1745de52009-05-22 21:49:51 +0200709 dma_debug_driver=<driver_name>
710 With this option the DMA-API debugging driver
711 filter feature can be enabled at boot time. Just
712 pass the driver to filter for as the parameter.
713 The filter can be disabled or changed to another
714 driver later using sysfs.
715
Carsten Emdeda0df922012-03-18 22:37:33 +0100716 drm_kms_helper.edid_firmware=[<connector>:]<file>
717 Broken monitors, graphic adapters and KVMs may
718 send no or incorrect EDID data sets. This parameter
719 allows to specify an EDID data set in the
720 /lib/firmware directory that is used instead.
721 Generic built-in EDID data sets are used, if one of
722 edid/1024x768.bin, edid/1280x1024.bin,
723 edid/1680x1050.bin, or edid/1920x1080.bin is given
724 and no file with the same name exists. Details and
725 instructions how to build your own EDID data are
726 available in Documentation/EDID/HOWTO.txt. An EDID
727 data set will only be used for a particular connector,
728 if its name and a colon are prepended to the EDID
729 name.
730
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 dscc4.setup= [NET]
732
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700733 earlycon= [KNL] Output early console device and options.
734 uart[8250],io,<addr>[,options]
735 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700736 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700737 Start an early, polled-mode console on the 8250/16550
738 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700739 MMIO inter-register address stride is either 8-bit
740 (mmio) or 32-bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700741 The options are the same as for ttyS, above.
742
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530743 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 earlyprintk=vga
745 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500746 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500747 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
Randy Dunlapa9913042005-10-23 12:57:11 -0700749 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 takes over.
751
Yinghai Lu5c059172008-07-24 17:29:40 -0700752 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753
754 Currently only ttyS0 and ttyS1 are supported.
755
756 Interaction with the standard serial driver is not
757 very good.
758
759 The VGA output is eventually overwritten by the real
760 console.
761
Jason Wessel97311912010-05-20 21:04:30 -0500762 ekgdboc= [X86,KGDB] Allow early kernel console debugging
763 ekgdboc=kbd
764
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300765 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500766 the boot argument: earlyprintk=vga
767
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700769 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 eisa_irq_edge= [PARISC,HW]
772 See header of drivers/parisc/eisa.c.
773
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700774 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700776 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777
778 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100779 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +0200780 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -0700781 Documentation/block/deadline-iosched.txt for details.
782
Michael Holzheud3bf37952011-10-30 15:16:37 +0100783 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -0700784 Specifies physical address of start of kernel core
Michael Holzheud3bf37952011-10-30 15:16:37 +0100785 image elf header and optionally the size. Generally
786 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -0800787 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700789 enable_mtrr_cleanup [X86]
790 The kernel tries to adjust MTRR layout from continuous
791 to discrete, to make X server driver able to add WB
792 entry later. This parameter enables that.
793
Randy Dunlapca1eda22009-05-06 16:02:58 -0700794 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700795 Enable PIN 1 of APIC timer
796 Can be useful to work around chipset bugs
797 (in particular on some ATI chipsets).
798 The kernel tries to set a reasonable default.
799
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 enforcing [SELINUX] Set initial enforcing status.
801 Format: {"0" | "1"}
802 See security/selinux/Kconfig help text.
803 0 -- permissive (log only, no denials).
804 1 -- enforcing (deny and log).
805 Default value is 0.
806 Value can be changed at runtime via /selinux/enforce.
807
Huang Yinga08f82d2010-05-18 14:35:21 +0800808 erst_disable [ACPI]
809 Disable Error Record Serialization Table (ERST)
810 support.
811
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 ether= [HW,NET] Ethernet cards parameters
813 This option is obsoleted by the "netdev=" option, which
814 has equivalent usage. See its documentation for details.
815
Mimi Zohar7102ebc2011-05-12 18:33:20 -0400816 evm= [EVM]
817 Format: { "fix" }
818 Permit 'security.evm' to be updated regardless of
819 current integrity status.
820
Akinobu Mitade1ba092006-12-08 02:39:42 -0800821 failslab=
822 fail_page_alloc=
823 fail_make_request=[KNL]
824 General fault injection mechanism.
825 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +0200826 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -0800827
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000829 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830
Alex Chiangf13ae302008-05-08 14:03:23 -0600831 force_pal_cache_flush
832 [IA-64] Avoid check_sal_cache_flush which may hang on
833 buggy SAL_CACHE_FLUSH implementations. Using this
834 parameter will force ia64_sal_cache_flush to call
835 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
836
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100837 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400838 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100839 as early as possible in order to facilitate early
840 boot debugging.
841
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200842 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400843 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200844 If no parameter is passed, ftrace will dump
845 buffers of all CPUs, but if you pass orig_cpu, it will
846 dump only the buffer of the CPU that triggered the
847 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400848
849 ftrace_filter=[function-list]
850 [FTRACE] Limit the functions traced by the function
851 tracer at boot up. function-list is a comma separated
852 list of functions. This list can be changed at run
853 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -0700854 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400855
856 ftrace_notrace=[function-list]
857 [FTRACE] Do not trace the functions specified in
858 function-list. This list can be changed at run time
859 by the set_ftrace_notrace file in the debugfs
860 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100861
Stefan Assmann369bc182009-10-12 22:17:21 +0200862 ftrace_graph_filter=[function-list]
863 [FTRACE] Limit the top level callers functions traced
864 by the function graph tracer at boot up.
865 function-list is a comma separated list of functions
866 that can be changed at run time by the
867 set_graph_function file in the debugfs tracing directory.
868
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 gamecon.map[2|3]=
870 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
871 support via parallel port (up to 5 devices per port)
872 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
873 See also Documentation/input/joystick-parport.txt
874
875 gamma= [HW,DRM]
876
Yinghai Luaaf23042008-01-30 13:33:09 +0100877 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
878 Format: off | on
879 default: on
880
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700881 gcov_persist= [GCOV] When non-zero (default), profiling data for
882 kernel modules is saved and remains accessible via
883 debugfs, even when the module is unloaded/reloaded.
884 When zero, profiling data is discarded and associated
885 debugfs files are removed at module unload time.
886
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 gpt [EFI] Forces disk with valid GPT signature but
888 invalid Protective MBR to be treated as GPT.
889
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 hashdist= [KNL,NUMA] Large hashes allocated during boot
891 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -0700892 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700893 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894
895 hcl= [IA-64] SGI's Hardware Graph compatibility layer
896
897 hd= [EIDE] (E)IDE hard drive subsystem geometry
898 Format: <cyl>,<head>,<sect>
899
Huang Yingea8c0712010-05-18 14:35:15 +0800900 hest_disable [ACPI]
901 Disable Hardware Error Source Table (HEST) support;
902 corresponding firmware-first mode error processing
903 logic will be disabled.
904
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
906 size of <nn>. This works even on boxes that have no
907 highmem otherwise. This also works to reduce highmem
908 size on bigger boxes.
909
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800910 highres= [KNL] Enable/disable high resolution timer mode.
911 Valid parameters: "on", "off"
912 Default: "on"
913
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 hisax= [HW,ISDN]
915 See Documentation/isdn/README.HiSax.
916
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700917 hlt [BUGS=ARM,SH]
918
919 hpet= [X86-32,HPET] option to control HPET usage
920 Format: { enable (default) | disable | force |
921 verbose }
922 disable: disable HPET and use PIT instead
923 force: allow force enabled of undocumented chips (ICH4,
924 VIA, nVidia)
925 verbose: show contents of HPET registers during setup
926
Andi Kleenb4718e62008-07-23 21:27:51 -0700927 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
928 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700929 On x86-64 and powerpc, this option can be specified
930 multiple times interleaved with hugepages= to reserve
931 huge pages of different sizes. Valid pages sizes on
932 x86-64 are 2M (when the CPU supports "pse") and 1G
933 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700934 Note that 1GB pages can only be allocated at boot time
935 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900936
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100937 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
938 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100939 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
940 If specified, z/VM IUCV HVC accepts connections
941 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100942
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700943 keep_bootcon [KNL]
944 Do not unregister boot console at start. This is only
945 useful for debugging when something happens in the window
946 between unregistering the boot console and initializing
947 the real console.
948
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700949 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700950 or register an additional I2C bus that is not
951 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700952 Format:
953 <bus_id>,<clkrate>
954
Jiri Kosina36d95732008-10-06 02:51:09 -0400955 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200957 i8042.dumbkbd [HW] Pretend that controller can only read data from
958 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 (Don't attempt to blink the leds)
960 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500961 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400962 i8042.noloop [HW] Disable the AUX Loopback command while probing
963 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 i8042.nomux [HW] Don't check presence of an active multiplexing
965 controller
966 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
967 controllers
Masanari Iida24775d62012-02-15 00:26:42 +0900968 i8042.notimeout [HW] Ignore timeout condition signalled by controller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 i8042.reset [HW] Reset the controller during init and cleanup
970 i8042.unlock [HW] Unlock (ignore) the keylock
971
972 i810= [HW,DRM]
973
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700974 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
975 indicates that the driver is running on unsupported
976 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
978 does not match list of supported models.
979 i8k.power_status
980 [HW] Report power status in /proc/i8k
981 (disabled by default)
982 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
983 capability is set.
984
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 icn= [HW,ISDN]
986 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
987
David Fries0af80c02009-02-25 20:28:21 +0100988 ide-core.nodma= [HW] (E)IDE subsystem
989 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200990 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
991 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100992 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700994 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
995 Claim all unknown PCI IDE storage controllers.
996
Andi Kleenf039b752007-05-02 19:27:12 +0200997 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800998 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
999 Poll forces a polling idle loop that can slightly
1000 improve the performance of waking up a idle CPU, but
1001 will use a lot of power and make the system run hot.
1002 Not recommended.
1003 idle=mwait: On systems which support MONITOR/MWAIT but
1004 the kernel chose to not use it because it doesn't save
1005 as much power as a normal idle loop, use the
1006 MONITOR/MWAIT idle loop anyways. Performance should be
1007 the same as idle=poll.
1008 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +08001009 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001010 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -07001011
Ingo Molnar792908222006-12-06 20:40:51 -08001012 ignore_loglevel [KNL]
1013 Ignore loglevel setting - this will print /all/
1014 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001015 We also add it as printk module parameter, so users
1016 could change it dynamically, usually by
1017 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -08001018
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 ihash_entries= [KNL]
1020 Set number of hash buckets for inode cache.
1021
Mimi Zohar3323eec2009-02-04 09:06:58 -05001022 ima_audit= [IMA]
1023 Format: { "0" | "1" }
1024 0 -- integrity auditing messages. (Default)
1025 1 -- enable informational integrity auditing messages.
1026
1027 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -07001028 Format: { "sha1" | "md5" }
Mimi Zohar3323eec2009-02-04 09:06:58 -05001029 default: "sha1"
1030
Eric Paris5789ba32009-05-21 15:47:06 -04001031 ima_tcb [IMA]
1032 Load a policy which meets the needs of the Trusted
1033 Computing Base. This means IMA will measure all
1034 programs exec'd, files mmap'd for exec, and all files
1035 opened for read by uid=0.
1036
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 init= [KNL]
1038 Format: <full_path>
1039 Run specified binary instead of /sbin/init as init
1040 process.
1041
1042 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1043 for working out where the kernel is dying during
1044 startup.
1045
1046 initrd= [BOOT] Specify the location of the initial ramdisk
1047
1048 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1049 Format: <irq>
1050
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001051 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001052 on
1053 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001054 off
1055 Disable intel iommu driver.
1056 igfx_off [Default Off]
1057 By default, gfx is mapped as normal device. If a gfx
1058 device has a dedicated DMAR unit, the DMAR unit is
1059 bypassed by not enabling DMAR with this option. In
1060 this case, gfx device will use physical address for
1061 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001062 forcedac [x86_64]
1063 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001064 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001065 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001066 than 32-bit addressing. The default is to look
1067 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001068 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001069 strict [Default Off]
1070 With this option on every unmap_single operation will
1071 result in a hardware IOTLB flush operation as opposed
1072 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001073 sp_off [Default Off]
1074 By default, super page will be supported if Intel IOMMU
1075 has the capability. With this option, super page will
1076 not be supported.
Masanari Iida2e92c7a2011-12-15 01:18:52 +09001077
1078 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1079 0 disables intel_idle and fall back on acpi_idle.
1080 1 to 6 specify maximum depth of C-state.
1081
Chris Wrightd1423d52010-07-20 11:06:49 -07001082 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001083 on enable Interrupt Remapping (default)
1084 off disable Interrupt Remapping
1085 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001086 no_x2apic_optout
1087 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001088
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001089 iomem= Disable strict checking of access to MMIO memory
1090 strict regions from userspace.
1091 relaxed
1092
1093 iommu= [x86]
1094 off
1095 force
1096 noforce
1097 biomerge
1098 panic
1099 nopanic
1100 merge
1101 nomerge
1102 forcesac
1103 soft
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001104 pt [x86, IA-64]
1105 group_mf [x86, IA-64]
1106
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001107
1108 io7= [HW] IO7 for Marvel based alpha systems
1109 See comment before marvel_specify_io7 in
1110 arch/alpha/kernel/core_marvel.c.
1111
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301112 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001113 0x80
1114 Standard port 0x80 based delay
1115 0xed
1116 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001117 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001118 Simple two microseconds delay
1119 none
1120 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001121
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001123 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
1125 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001126 See comment before ip2_setup() in
1127 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
Alan Cox200803d2005-06-28 20:45:18 -07001129 irqfixup [HW]
1130 When an interrupt is not handled search all handlers
1131 for it. Intended to get systems with badly broken
1132 firmware running.
1133
1134 irqpoll [HW]
1135 When an interrupt is not handled search all handlers
1136 for it. Also check all handlers each timer
1137 interrupt. Intended to get systems with badly broken
1138 firmware running.
1139
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001141 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142
1143 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001144 Format:
1145 <cpu number>,...,<cpu number>
1146 or
Li Zefanb225d442008-11-06 12:53:39 -08001147 <cpu number>-<cpu number>
1148 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001149 or a mixture
1150 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001151
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 This option can be used to specify one or more CPUs
1153 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001154 algorithms. You can move a process onto or off an
1155 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 <cpu number> begins at 0 and the maximum value is
1157 "number of CPUs in system - 1".
1158
1159 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001160 alternative -- manually setting the CPU mask of all
1161 tasks in the system -- can cause problems and
1162 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163
Randy Dunlapa9913042005-10-23 12:57:11 -07001164 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165
1166 js= [HW,JOY] Analog joystick
1167 See Documentation/input/joystick.txt.
1168
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001169 keepinitrd [HW,ARM]
1170
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301171 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001172 specifies the amount of memory usable by the kernel
1173 for non-movable allocations. The requested amount is
1174 spread evenly throughout all nodes in the system. The
1175 remaining memory in each node is used for Movable
1176 pages. In the event, a node is too small to have both
1177 kernelcore and Movable pages, kernelcore pages will
1178 take priority and other nodes will have a larger number
1179 of kernelcore pages. The Movable zone is used for the
1180 allocation of pages that may be reclaimed or moved
1181 by the page migration subsystem. This means that
1182 HugeTLB pages may not be allocated from this zone.
1183 Note that allocations like PTEs-from-HighMem still
1184 use the HighMem zone if it exists, and the Normal
1185 zone if it does not.
1186
Jason Wessel4fe1da42010-05-20 21:04:31 -05001187 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1188 Format: <Controller#>[,poll interval]
1189 The controller # is the number of the ehci usb debug
1190 port as it is probed via PCI. The poll interval is
1191 optional and is the number seconds in between
1192 each poll cycle to the debug port in case you need
1193 the functionality for interrupting the kernel with
1194 gdb or control-c on the dbgp connection. When
1195 not using this parameter you use sysrq-g to break into
1196 the kernel debugger.
1197
Jason Wessel84c08fd2010-05-20 21:04:24 -05001198 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001199 Requires a tty driver that supports console polling,
1200 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001201 Serial only format: <serial_device>[,baud]
1202 keyboard only format: kbd
1203 keyboard and serial format: kbd,<serial_device>[,baud]
1204 Optional Kernel mode setting:
1205 kms, kbd format: kms,kbd
1206 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001207
Jason Wessel84c08fd2010-05-20 21:04:24 -05001208 kgdbwait [KGDB] Stop kernel execution and enter the
1209 kernel debugger at the earliest opportunity.
1210
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001211 kmac= [MIPS] korina ethernet MAC address.
1212 Configure the RouterBoard 532 series on-chip
1213 Ethernet adapter MAC address.
1214
Catalin Marinas04f70332009-06-11 13:22:39 +01001215 kmemleak= [KNL] Boot-time kmemleak enable/disable
1216 Valid arguments: on, off
1217 Default: on
1218
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301219 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001220 in oops dumps.
1221
Andre Przywarafef07aa2009-07-10 14:20:35 +02001222 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1223 Default is 0 (don't ignore, but inject #GP)
1224
Xiao Guangronga182d872010-09-20 22:17:48 +08001225 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1226 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001227 Default is 0 (off)
1228
Andre Przywarafef07aa2009-07-10 14:20:35 +02001229 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001230 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001231
1232 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1233 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001234 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001235
Andre Przywarafef07aa2009-07-10 14:20:35 +02001236 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1237 (virtualized MMU) support on capable Intel chips.
1238 Default is 1 (enabled)
1239
1240 kvm-intel.emulate_invalid_guest_state=
1241 [KVM,Intel] Enable emulation of invalid guest states
1242 Default is 0 (disabled)
1243
1244 kvm-intel.flexpriority=
1245 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1246 Default is 1 (enabled)
1247
Sasha Levine1a72ae2011-08-09 14:28:35 +03001248 kvm-intel.nested=
1249 [KVM,Intel] Enable VMX nesting (nVMX).
1250 Default is 0 (disabled)
1251
Andre Przywarafef07aa2009-07-10 14:20:35 +02001252 kvm-intel.unrestricted_guest=
1253 [KVM,Intel] Disable unrestricted guest feature
1254 (virtualized real and unpaged mode) on capable
1255 Intel chips. Default is 1 (enabled)
1256
1257 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1258 feature (tagged TLBs) on capable Intel chips.
1259 Default is 1 (enabled)
1260
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 l2cr= [PPC]
1262
Robert Brosea78bfbf2008-03-29 07:20:23 +11001263 l3cr= [PPC]
1264
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001265 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001266 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301268 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001269 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001270
FD Camifcb71f62008-01-06 19:08:56 +01001271 libata.dma= [LIBATA] DMA control
1272 libata.dma=0 Disable all PATA and SATA DMA
1273 libata.dma=1 PATA and SATA Disk DMA only
1274 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001275 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001276 Combinations also work, so libata.dma=3 enables DMA
1277 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001278
Michael Prokop20308872009-08-06 00:14:10 +02001279 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1280 libata.ignore_hpa=0 keep BIOS limits (default)
1281 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001282
Dave Jones78e70c22007-09-27 11:50:13 -04001283 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1284 when set.
1285 Format: <int>
1286
Tejun Heo33267322008-02-13 09:15:09 +09001287 libata.force= [LIBATA] Force configurations. The format is comma
1288 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001289 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001290 matching port, link or device. Basically, it matches
1291 the ATA ID string printed on console by libata. If
1292 the whole ID part is omitted, the last PORT and DEVICE
1293 values are used. If ID hasn't been specified yet, the
1294 configuration applies to all ports, links and devices.
1295
1296 If only DEVICE is omitted, the parameter applies to
1297 the port and all links and devices behind it. DEVICE
1298 number of 0 either selects the first device or the
1299 first fan-out link behind PMP device. It does not
1300 select the host link. DEVICE number of 15 selects the
1301 host link and device attached to it.
1302
1303 The VAL specifies the configuration to force. As long
1304 as there's no ambiguity shortcut notation is allowed.
1305 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1306 The following configurations can be forced.
1307
1308 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1309 Any ID with matching PORT is used.
1310
1311 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1312
1313 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1314 udma[/][16,25,33,44,66,100,133] notation is also
1315 allowed.
1316
1317 * [no]ncq: Turn on or off NCQ.
1318
Tejun Heo05944bd2008-08-13 20:19:09 +09001319 * nohrst, nosrst, norst: suppress hard, soft
1320 and both resets.
1321
Tejun Heo43c9c592010-05-23 12:59:11 +02001322 * dump_id: dump IDENTIFY data.
1323
Tejun Heo33267322008-02-13 09:15:09 +09001324 If there are multiple matching configurations changing
1325 the same attribute, the last one is used.
1326
Yinghai Lu95f72d12010-07-12 14:36:09 +10001327 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be252009-01-06 14:42:44 -08001328
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001330 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001332 lockd.nlm_grace_period=P [NFS] Assign grace period.
1333 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001335 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1336 Format: <integer>
1337
1338 lockd.nlm_timeout=T [NFS] Assign timeout value.
1339 Format: <integer>
1340
1341 lockd.nlm_udpport=M [NFS] Assign UDP port.
1342 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343
1344 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1345 Format: <irq>
1346
1347 loglevel= All Kernel Messages with a loglevel smaller than the
1348 console loglevel will be printed to the console. It can
1349 also be changed with klogd or other programs. The
1350 loglevels are defined as follows:
1351
1352 0 (KERN_EMERG) system is unusable
1353 1 (KERN_ALERT) action must be taken immediately
1354 2 (KERN_CRIT) critical conditions
1355 3 (KERN_ERR) error conditions
1356 4 (KERN_WARNING) warning conditions
1357 5 (KERN_NOTICE) normal but significant condition
1358 6 (KERN_INFO) informational
1359 7 (KERN_DEBUG) debug-level messages
1360
Randy Dunlapc756d082011-02-20 20:08:35 -08001361 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1362 in bytes. n must be a power of two. The default
1363 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364
Randy Dunlapaccaa242007-10-16 01:29:37 -07001365 logo.nologo [FB] Disables display of the built-in Linux logo.
1366 This may be used to provide more screen space for
1367 kernel log messages and is useful when debugging
1368 kernel boot problems.
1369
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 lp=0 [LP] Specify parallel ports to use, e.g,
1371 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1372 lp=reset first parallel port). 'lp=0' disables the
1373 lp=auto printer driver. 'lp=reset' (which can be
1374 specified in addition to the ports) causes
1375 attached printers to be reset. Using
1376 lp=port1,port2,... specifies the parallel ports
1377 to associate lp devices with, starting with
1378 lp0. A port specification may be 'none' to skip
1379 that lp device, or a parport name such as
1380 'parport0'. Specifying 'lp=auto' instead of a
1381 port specification list means that device IDs
1382 from each port should be examined, to see if
1383 an IEEE 1284-compliant printer is attached; if
1384 so, the driver will manage that printer.
1385 See also header of drivers/char/lp.c.
1386
1387 lpj=n [KNL]
1388 Sets loops_per_jiffy to given constant, thus avoiding
1389 time-consuming boot-time autodetection (up to 250 ms per
1390 CPU). 0 enables autodetection (default). To determine
1391 the correct value for your kernel, boot with normal
1392 autodetection and see what value is printed. Note that
1393 on SMP systems the preset will be applied to all CPUs,
1394 which is likely to cause problems if your CPUs need
1395 significantly divergent settings. An incorrect value
1396 will cause delays in the kernel to be wrong, leading to
1397 unpredictable I/O errors and other breakage. Although
1398 unlikely, in the extreme case this might damage your
1399 hardware.
1400
1401 ltpc= [NET]
1402 Format: <io>,<irq>,<dma>
1403
Randy Dunlap16290242011-08-13 12:34:52 -07001404 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001405 (machvec) in a generic kernel.
1406 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407
Wu Zhangjin3209e702009-07-02 23:27:12 +08001408 machtype= [Loongson] Share the same kernel image file between different
1409 yeeloong laptop.
1410 Example: machtype=lemote-yeeloong-2f-7inch
1411
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001412 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1413 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414
1415 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001416 should make use of. maxcpus=n : n >= 0 limits the
1417 kernel to using 'n' processors. n=0 is a special case,
1418 it is equivalent to "nosmp", which also disables
1419 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420
Kay Sieversd134b002011-07-31 22:08:04 +02001421 max_loop= [LOOP] The number of loop block devices that get
1422 (loop.max_loop) unconditionally pre-created at init time. The default
1423 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1424 of statically allocating a predefined number, loop
1425 devices can be requested on-demand with the
1426 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001427
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 mcatest= [IA-64]
1429
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001430 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Uwe Hermann71cced62008-10-20 09:32:21 -07001432 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001433
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 md= [HW] RAID subsystems devices and level
1435 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 mdacon= [MDA]
1438 Format: <first>,<last>
1439 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001440
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1442 Amount of memory to be used when the kernel is not able
1443 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001444 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 address space collisions. Without memmap= PCI devices
1446 could be placed at addresses belonging to unused RAM.
1447
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001448 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 memory.
1450
Paul Mundt6902aa82008-09-21 17:14:42 +09001451 memchunk=nn[KMG]
1452 [KNL,SH] Allow user to override the default size for
1453 per-device physically contiguous DMA buffers.
1454
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301455 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456 E820 memory map, as specified by the user.
1457 Such memmap=exactmap lines can be constructed based on
1458 BIOS output or other requirements. See the memmap=nn@ss
1459 option description.
1460
1461 memmap=nn[KMG]@ss[KMG]
1462 [KNL] Force usage of a specific region of memory
1463 Region of memory to be used, from ss to ss+nn.
1464
1465 memmap=nn[KMG]#ss[KMG]
1466 [KNL,ACPI] Mark specific memory as ACPI data.
1467 Region of memory to be used, from ss to ss+nn.
1468
1469 memmap=nn[KMG]$ss[KMG]
1470 [KNL,ACPI] Mark specific memory as reserved.
1471 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001472 Example: Exclude memory from 0x18690000-0x1869ffff
1473 memmap=64K$0x18690000
1474 or
1475 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001477 memory_corruption_check=0/1 [X86]
1478 Some BIOSes seem to corrupt the first 64k of
1479 memory when doing things like suspend/resume.
1480 Setting this option will scan the memory
1481 looking for corruption. Enabling this will
1482 both detect corruption and prevent the kernel
1483 from using the memory being corrupted.
1484 However, its intended as a diagnostic tool; if
1485 repeatable BIOS-originated corruption always
1486 affects the same memory, you can use memmap=
1487 to prevent the kernel from using that memory.
1488
1489 memory_corruption_check_size=size [X86]
1490 By default it checks for corruption in the low
1491 64k, making this memory unavailable for normal
1492 use. Use this parameter to scan for
1493 corruption in more or less memory.
1494
1495 memory_corruption_check_period=seconds [X86]
1496 By default it checks for corruption every 60
1497 seconds. Use this parameter to check at some
1498 other rate. 0 disables periodic checking.
1499
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001500 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001501 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001502 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001503 Specifies the number of memtest passes to be
1504 performed. Each pass selects another test
1505 pattern from a given set of patterns. Memtest
1506 fills the memory with this pattern, validates
1507 memory contents and reserves bad memory
1508 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001509
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 meye.*= [HW] Set MotionEye Camera parameters
1511 See Documentation/video4linux/meye.txt.
1512
Andres Salomon8f368812007-10-12 23:04:06 +02001513 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1514 Multi-Function General Purpose Timers on AMD Geode
1515 platforms.
1516
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001517 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1518 the BIOS has incorrectly applied a workaround. TinyBIOS
1519 version 0.98 is known to be affected, 0.99 fixes the
1520 problem by letting the user disable the workaround.
1521
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 mga= [HW,DRM]
1523
Randy Dunlap1c207f92008-11-19 15:36:16 -08001524 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1525 physical address is ignored.
1526
Michel Pollet39f45d72009-05-20 11:10:31 +01001527 mini2440= [ARM,HW,KNL]
1528 Format:[0..2][b][c][t]
1529 Default: "0tb"
1530 MINI2440 configuration specification:
1531 0 - The attached screen is the 3.5" TFT
1532 1 - The attached screen is the 7" TFT
1533 2 - The VGA Shield is attached (1024x768)
1534 Leaving out the screen size parameter will not load
1535 the TFT driver, and the framebuffer will be left
1536 unconfigured.
1537 b - Enable backlight. The TFT backlight pin will be
1538 linked to the kernel VESA blanking code and a GPIO
1539 LED. This parameter is not necessary when using the
1540 VGA shield.
1541 c - Enable the s3c camera interface.
1542 t - Reserved for enabling touchscreen support. The
1543 touchscreen support is not enabled in the mainstream
1544 kernel as of 2.6.30, a preliminary port can be found
1545 in the "bleeding edge" mini2440 support kernel at
1546 http://repo.or.cz/w/linux-2.6/mini2440.git
1547
Mel Gorman6b74ab92008-07-23 21:26:49 -07001548 mminit_loglevel=
1549 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1550 parameter allows control of the logging verbosity for
1551 the additional memory initialisation checks. A value
1552 of 0 disables mminit logging and a level of 4 will
1553 log everything. Information is printed at KERN_DEBUG
1554 so loglevel=8 may also need to be specified.
1555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 mousedev.tap_time=
1557 [MOUSE] Maximum time between finger touching and
1558 leaving touchpad surface for touch to be considered
1559 a tap and be reported as a left button click (for
1560 touchpads working in absolute mode only).
1561 Format: <msecs>
1562 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1563 reporting absolute coordinates, such as tablets
1564 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1565 reporting absolute coordinates, such as tablets
1566
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301567 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001568 is similar to kernelcore except it specifies the
1569 amount of memory used for migratable allocations.
1570 If both kernelcore and movablecore is specified,
1571 then kernelcore will be at *least* the specified
1572 value but may be more. If movablecore on its own
1573 is specified, the administrator must be careful
1574 that the amount of memory usable for all allocations
1575 is not too small.
1576
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 MTD_Partition= [MTD]
1578 Format: <name>,<region-number>,<size>,<offset>
1579
Randy Dunlapa9913042005-10-23 12:57:11 -07001580 MTD_Region= [MTD] Format:
1581 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582
1583 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001584 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001586 multitce=off [PPC] This parameter disables the use of the pSeries
1587 firmware feature for updating multiple TCE entries
1588 at a time.
1589
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001590 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1591
1592 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1593
1594 boundary - index of last SLC block on Flex-OneNAND.
1595 The remaining blocks are configured as MLC blocks.
1596 lock - Configure if Flex-OneNAND boundary should be locked.
1597 Once locked, the boundary cannot be changed.
1598 1 indicates lock status, 0 indicates unlock status.
1599
Ben Dooks9db829f2008-07-03 11:24:29 +01001600 mtdset= [ARM]
1601 ARM/S3C2412 JIVE boot control
1602
1603 See arch/arm/mach-s3c2412/mach-jive.c
1604
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001606 [HW] Make the MicroTouch USB driver use raw coordinates
1607 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001609 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001610 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001611 that could hold holes aka. UC entries.
1612
1613 mtrr_gran_size=nn[KMG] [X86]
1614 Used for mtrr cleanup. It is granularity of mtrr block.
1615 Default is 1.
1616 Large value could prevent small alignment from
1617 using up MTRRs.
1618
1619 mtrr_spare_reg_nr=n [X86]
1620 Format: <integer>
1621 Range: 0,7 : spare reg number
1622 Default : 1
1623 Used for mtrr cleanup. It is spare mtrr entries number.
1624 Set to 2 or more if your graphical card needs more.
1625
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1627
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 netdev= [NET] Network devices parameters
1629 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1630 Note that mem_start is often overloaded to mean
1631 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001632 This usage is only documented in each driver source
1633 file if at all.
1634
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001635 nf_conntrack.acct=
1636 [NETFILTER] Enable connection tracking flow accounting
1637 0 to disable accounting
1638 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001639 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001640
Chuck Lever306a0752010-09-17 10:54:37 -04001641 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001642 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643
1644 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001645 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646
Chuck Lever306a0752010-09-17 10:54:37 -04001647 nfsrootdebug [NFS] enable nfsroot debugging messages.
1648 See Documentation/filesystems/nfs/nfsroot.txt.
1649
Trond Myklebusta72b4422006-01-03 09:55:41 +01001650 nfs.callback_tcpport=
1651 [NFS] set the TCP port on which the NFSv4 callback
1652 channel should listen.
1653
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001654 nfs.cache_getent=
1655 [NFS] sets the pathname to the program which is used
1656 to update the NFS client cache entries.
1657
1658 nfs.cache_getent_timeout=
1659 [NFS] sets the timeout after which an attempt to
1660 update a cache entry is deemed to have failed.
1661
Trond Myklebust58df0952006-01-03 09:55:57 +01001662 nfs.idmap_cache_timeout=
1663 [NFS] set the maximum lifetime for idmapper cache
1664 entries.
1665
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001666 nfs.enable_ino64=
1667 [NFS] enable 64-bit inode numbers.
1668 If zero, the NFS client will fake up a 32-bit inode
1669 number for the readdir() and stat() syscalls instead
1670 of returning the full 64-bit number.
1671 The default is to return 64-bit inode numbers.
1672
Trond Myklebustef159e92012-02-06 19:50:40 -05001673 nfs.max_session_slots=
1674 [NFSv4.1] Sets the maximum number of session slots
1675 the client will attempt to negotiate with the server.
1676 This limits the number of simultaneous RPC requests
1677 that the client can send to the NFSv4.1 server.
1678 Note that there is little point in setting this
1679 value higher than the max_tcp_slot_table_limit.
1680
Trond Myklebustb064eca22011-02-22 15:44:32 -08001681 nfs.nfs4_disable_idmapping=
Trond Myklebust074b1d12012-01-09 13:46:26 -05001682 [NFSv4] When set to the default of '1', this option
1683 ensures that both the RPC level authentication
1684 scheme and the NFS level operations agree to use
1685 numeric uids/gids if the mount is using the
1686 'sec=sys' security flavour. In effect it is
1687 disabling idmapping, which can make migration from
1688 legacy NFSv2/v3 systems to NFSv4 easier.
1689 Servers that do not support this mode of operation
1690 will be autodetected by the client, and it will fall
1691 back to using the idmapper.
1692 To turn off this behaviour, set the value to '0'.
Trond Myklebustb064eca22011-02-22 15:44:32 -08001693
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05001694 nfs.send_implementation_id =
1695 [NFSv4.1] Send client implementation identification
1696 information in exchange_id requests.
1697 If zero, no implementation identification information
1698 will be sent.
1699 The default is to send the implementation identification
1700 information.
1701
1702
Sachin Bhamare18d98f62012-03-19 20:47:58 -07001703 objlayoutdriver.osd_login_prog=
1704 [NFS] [OBJLAYOUT] sets the pathname to the program which
1705 is used to automatically discover and login into new
1706 osd-targets. Please see:
1707 Documentation/filesystems/pnfs.txt for more explanations
1708
Paul Mundt1e1030d2009-09-01 17:38:32 +09001709 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001710 when a NMI is triggered.
1711 Format: [state][,regs][,debounce][,die]
1712
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301713 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001714 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001715 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001716 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001717 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001718 timeout occurs (or 'nopanic' to override the opposite
1719 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001720 This is useful when you use a panic=... timeout and
1721 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722
Anton Vorontsovbff38772009-07-08 11:10:56 -07001723 netpoll.carrier_timeout=
1724 [NET] Specifies amount of time (in seconds) that
1725 netpoll should wait for a carrier. By default netpoll
1726 waits 4 seconds.
1727
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001728 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 emulation library even if a 387 maths coprocessor
1730 is present.
1731
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001732 no_console_suspend
1733 [HW] Never suspend the console
1734 Disable suspending of consoles during suspend and
1735 hibernate operations. Once disabled, debugging
1736 messages can reach various consoles while the rest
1737 of the system is being put to sleep (ie, while
1738 debugging driver suspend/resume hooks). This may
1739 not work reliably with all consoles, but is known
1740 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07001741 To facilitate more flexible debugging, we also add
1742 console_suspend, a printk module parameter to control
1743 it. Users could use console_suspend (usually
1744 /sys/module/printk/parameters/console_suspend) to
1745 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001746
Christoph Lameterc1aee212007-05-31 00:40:47 -07001747 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1748 caches in the slab allocator. Saves per-node memory,
1749 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001750
Randy Dunlapa9913042005-10-23 12:57:11 -07001751 noalign [KNL,ARM]
1752
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753 noapic [SMP,APIC] Tells the kernel to not make use of any
1754 IOAPICs that may be present in the system.
1755
Mike Galbraith5091faa2010-11-30 14:18:03 +01001756 noautogroup Disable scheduler automatic task group creation.
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 nobats [PPC] Do not use BATs for mapping kernel lowmem
1759 on "Classic" PPC cores.
1760
1761 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001762
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001763 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1764
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001765 nodelayacct [KNL] Disable per-task delay accounting
1766
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1768
Paul Mundt6902aa82008-09-21 17:14:42 +09001769 nodsp [SH] Disable hardware DSP at boot time.
1770
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301771 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001772
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 noexec [IA-64]
1774
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301775 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001776 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001778 noexec=off: disable non-executable mappings
1779
Fenghua Yude5397a2011-05-11 16:51:05 -07001780 nosmep [X86]
1781 Disable SMEP (Supervisor Mode Execution Protection)
1782 even if it is supported by processor.
1783
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001784 noexec32 [X86-64]
1785 This affects only 32-bit executables.
1786 noexec32=on: enable non-executable mappings (default)
1787 read doesn't imply executable mappings
1788 noexec32=off: disable non-executable mappings
1789 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790
Paul Mundt6902aa82008-09-21 17:14:42 +09001791 nofpu [SH] Disable hardware FPU at boot time.
1792
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001793 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001794 register save and restore. The kernel will only save
1795 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796
Suresh Siddha0c752a92009-05-22 12:17:45 -07001797 noxsave [BUGS=X86] Disables x86 extended register state save
1798 and restore using xsave. The kernel will fallback to
1799 enabling legacy floating-point and sse state.
1800
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001801 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1802 wfi(ARM) instruction doesn't work correctly and not to
1803 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001804
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001805 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 instruction doesn't work correctly and not to
1807 use it.
1808
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001809 no_file_caps Tells the kernel not to honor file capabilities. The
1810 only way then for a file to be executed with privilege
1811 is to be setuid root or executed by root.
1812
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 nohalt [IA-64] Tells the kernel not to use the power saving
1814 function PAL_HALT_LIGHT when idle. This increases
1815 power-consumption. On the positive side, it reduces
1816 interrupt wake-up latency, which may improve performance
1817 in certain environments such as networked servers or
1818 real-time systems.
1819
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001820 nohz= [KNL] Boottime enable/disable dynamic ticks
1821 Valid arguments: on, off
1822 Default: on
1823
Paul Mundteeee7852009-04-02 12:31:16 +09001824 noiotrap [SH] Disables trapped I/O port accesses.
1825
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001826 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 disable unhandled interrupt sources.
1828
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301829 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001830 broken timer IRQ sources.
1831
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 noisapnp [ISAPNP] Disables ISA PnP code.
1833
1834 noinitrd [RAM] Tells the kernel not to load any configured
1835 initial RAM disk.
1836
Weidong Han03ea8152009-04-17 16:42:15 +08001837 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1838 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001839 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001840
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 nointroute [IA-64]
1842
Randy Dunlap16290242011-08-13 12:34:52 -07001843 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07001844
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001845 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1846
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001847 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1848 fault handling.
1849
Glauber Costad910f5c2011-07-11 15:28:19 -04001850 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1851 steal time is computed, but won't influence scheduler
1852 behaviour
1853
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001854 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001856 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001857
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858 noltlbs [PPC] Do not use large page/tlb entries for kernel
1859 lowmem mapping on PPC40x.
1860
Horms312f1f02006-02-22 09:57:55 +09001861 nomca [IA-64] Disable machine check abort handling
1862
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001863 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001864
Andres Salomon83d73842007-10-12 23:04:06 +02001865 nomfgpt [X86-32] Disable Multi-Function General Purpose
1866 Timer usage (for AMD Geode machines).
1867
Don Zickusbda62632011-10-13 15:14:27 -04001868 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
1869 shutdown the other cpus. Instead use the REBOOT_VECTOR
1870 irq.
1871
Jiri Kosina016ddd92010-01-18 17:05:40 +01001872 nopat [X86] Disable PAT (page attribute table extension of
1873 pagetables) support.
1874
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001875 norandmaps Don't use address space randomization. Equivalent to
1876 echo 0 > /proc/sys/kernel/randomize_va_space
1877
Jiri Kosinabbff2162010-08-11 18:34:09 +02001878 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001879
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001880 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001881 with UP alternatives
1882
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883 noresidual [PPC] Don't use residual data on PReP machines.
1884
H. Peter Anvin49d859d2011-07-31 14:02:19 -07001885 nordrand [X86] Disable the direct use of the RDRAND
1886 instruction even if it is supported by the
1887 processor. RDRAND is still available to user
1888 space applications.
1889
Randy Dunlapa9913042005-10-23 12:57:11 -07001890 noresume [SWSUSP] Disables resume and restores original swap
1891 space.
1892
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 no-scroll [VGA] Disables scrollback.
1894 This is required for the Braillex ib80-piezo Braille
1895 reader made by F.H. Papenmeier (Germany).
1896
1897 nosbagart [IA-64]
1898
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001899 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001900
Len Brown61ec7562007-08-16 03:34:22 -04001901 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1902 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903
Dave Jones97842212007-07-15 23:41:05 -07001904 nosoftlockup [KNL] Disable the soft-lockup detector.
1905
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 nosync [HW,M68K] Disables sync negotiation for all devices.
1907
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001908 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909
1910 nousb [USB] Disable the USB subsystem
1911
Ben Hutchings55142372011-01-02 23:02:42 +00001912 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04001913
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001915
Weidong Han2b2fd872009-04-17 16:42:12 +08001916 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1917
Randy Dunlap16290242011-08-13 12:34:52 -07001918 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07001919 purges which is reported from either PAL_VM_SUMMARY or
1920 SAL PALO.
1921
Yinghai Lu2b633e32010-02-10 01:20:37 -08001922 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1923 could support. nr_cpus=n : n >= 1 limits the kernel to
1924 supporting 'n' processors. Later in runtime you can not
1925 use hotplug cpu feature to put more cpu back to online.
1926 just like you compile the kernel NR_CPUS=n
1927
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001928 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1929
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001930 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1931 one of ['zone', 'node', 'default'] can be specified
1932 This can be set from sysctl after boot.
1933 See Documentation/sysctl/vm.txt for details.
1934
Randy Dunlap7c4be252009-01-06 14:42:44 -08001935 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1936 See Documentation/debugging-via-ohci1394.txt for more
1937 info.
1938
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001939 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1940 Rather than timing out after 20 ms if an EC
1941 command is not properly ACKed, override the length
1942 of the timeout. We have interrupts disabled while
1943 waiting for the ACK, so if this is set too high
1944 interrupts *may* be lost!
1945
Tony Lindgren15ac7af2009-12-11 16:16:32 -08001946 omap_mux= [OMAP] Override bootloader pin multiplexing.
1947 Format: <mux_mode0.mode_name=value>...
1948 For example, to override I2C bus2:
1949 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1950
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 oprofile.timer= [HW]
1952 Use timer interrupt instead of performance counters
1953
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001954 oprofile.cpu_type= Force an oprofile cpu type
1955 This might be useful if you have an older oprofile
1956 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001957 Format: { arch_perfmon }
1958 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001959 perfmon on Intel CPUs instead of the
1960 CPU specific event set.
Robert Richter159a80b2011-10-11 19:39:16 +02001961 timer: [X86] Force use of architectural NMI
1962 timer mode (see also oprofile.timer
1963 for generic hr timer mode)
Andreas Krebbeldd3c4672011-11-25 20:03:05 +01001964 [s390] Force legacy basic mode sampling
1965 (report cpu_type "timer")
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001966
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001967 oops=panic Always panic on oopses. Default is to just kill the
1968 process, but there is a small probability of
1969 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07001970 This will also cause panics on machine check exceptions.
1971 Useful together with panic=30 to trigger a reboot.
1972
Randy Dunlapbcfde332010-06-07 17:10:38 -07001973 OSS [HW,OSS]
1974 See Documentation/sound/oss/oss-parameters.txt
1975
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07001976 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07001977 timeout > 0: seconds before rebooting
1978 timeout = 0: wait forever
1979 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980 Format: <timeout>
1981
1982 parkbd.port= [HW] Parallel port number the keyboard adapter is
1983 connected to, default is 0.
1984 Format: <parport#>
1985 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1986 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001987 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988
Randy Dunlapa9913042005-10-23 12:57:11 -07001989 parport= [HW,PPT] Specify parallel ports. 0 disables.
1990 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1991 Use 'auto' to force the driver to use any
1992 IRQ/DMA settings detected (the default is to
1993 ignore detected IRQ/DMA settings because of
1994 possible conflicts). You can specify the base
1995 address, IRQ, and DMA settings; IRQ and DMA
1996 should be numbers, or 'auto' (for using detected
1997 settings on that particular port), or 'nofifo'
1998 (to avoid using a FIFO even if it is detected).
1999 Parallel ports are assigned in the order they
2000 are specified on the command line, starting
2001 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002
Randy Dunlapa9913042005-10-23 12:57:11 -07002003 parport_init_mode= [HW,PPT]
2004 Configure VIA parallel port to operate in
2005 a specific mode. This is necessary on Pegasos
2006 computer where firmware has no options for setting
2007 up parallel port mode and sets it to spp.
2008 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 Format: [spp|ps2|epp|ecp|ecpepp]
2010
Andrew Mortondd287792006-03-23 03:00:57 -08002011 pause_on_oops=
2012 Halt all CPUs after the first oops has been printed for
2013 the specified number of seconds. This is to be used if
2014 your oopses keep scrolling off the screen.
2015
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 pcbit= [HW,ISDN]
2017
2018 pcd. [PARIDE]
2019 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002020 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021
Randy Dunlapa9913042005-10-23 12:57:11 -07002022 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07002023 earlydump [X86] dump PCI config space before the kernel
2024 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02002025 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002026 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07002027 the hardware directly. Use this if your machine
2028 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002029 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07002030 hardware access methods are allowed. Use this
2031 if you experience crashes upon bootup and you
2032 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002033 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002034 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02002035 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002036 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07002037 noaer [PCIE] If the PCIEAER kernel config parameter is
2038 enabled, this kernel boot option can be used to
2039 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04002040 nodomains [PCI] Disable support for multiple PCI
2041 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302042 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08002043 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02002044 check_enable_amd_mmconf [X86] check for and enable
2045 properly configured MMIO access to PCI
2046 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07002047 nomsi [MSI] If the PCI_MSI kernel config parameter is
2048 enabled, this kernel boot option can be used to
2049 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02002050 noioapicquirk [APIC] Disable all boot interrupt quirks.
2051 Safety option to keep boot IRQs enabled. This
2052 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02002053 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2054 primary IO-APIC for bridges that cannot disable
2055 boot IRQs. This fixes a source of spurious IRQs
2056 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02002057 noioapicreroute [APIC] Disable workaround that uses the
2058 boot IRQ equivalent of an IRQ that connects to
2059 a chipset where boot IRQs cannot be disabled.
2060 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002061 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07002062 routing table. These calls are known to be buggy
2063 on several machines and they hang the machine
2064 when used, but on other computers it's the only
2065 way to get the interrupt routing table. Try
2066 this option if the kernel is unable to allocate
2067 IRQs or discover secondary PCI buses on your
2068 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02002069 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07002070 Use with caution as certain devices share
2071 address decoders between ROMs and other
2072 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02002073 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07002074 expansion ROMs that do not already have
2075 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07002076 nobar [X86] Do not assign address space to the
2077 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002078 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002079 assigned automatically to PCI devices. You can
2080 make the kernel exclude IRQs of your ISA cards
2081 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002082 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002083 of the PIRQ table (normally generated
2084 by the BIOS) if it is outside the
2085 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002086 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002087 useful if the kernel is unable to find your
2088 secondary buses and you want to tell it
2089 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002090 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002091 numbers ourselves, overriding
2092 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002093 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002094 in the BIOS $PIR table. This is needed on
2095 some systems with broken BIOSes, notably
2096 some HP Pavilion N5400 and Omnibook XE3
2097 notebooks. This will have no effect if ACPI
2098 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002099 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002100 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002101 use_crs [X86] Use PCI host bridge window information
2102 from ACPI. On BIOSes from 2008 or later, this
2103 is enabled by default. If you need to use this,
2104 please report a bug.
2105 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2106 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002107 routeirq Do IRQ routing for all PCI devices.
2108 This is normally done in pci_enable_device(),
2109 so this option is a temporary workaround
2110 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002111 skip_isa_align [X86] do not align io start addr, so can
2112 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002113 firmware [ARM] Do not re-enumerate the bus but instead
2114 just use the configuration from the
2115 bootloader. This is currently used on
2116 IXP2000 systems where the bus has to be
2117 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002118 noearly [X86] Don't do any early type 1 scanning.
2119 This might help on some broken boards which
2120 machine check when some devices' config space
2121 is read. But various workarounds are disabled
2122 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002123 bfsort Sort PCI devices into breadth-first order.
2124 This sorting is done to get a device
2125 order compatible with older (<= 2.4) kernels.
2126 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002127 cbiosize=nn[KMG] The fixed amount of bus space which is
2128 reserved for the CardBus bridge's IO window.
2129 The default value is 256 bytes.
2130 cbmemsize=nn[KMG] The fixed amount of bus space which is
2131 reserved for the CardBus bridge's memory
2132 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002133 resource_alignment=
2134 Format:
2135 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2136 Specifies alignment and device to reassign
2137 aligned memory resources.
2138 If <order of align> is not specified,
2139 PAGE_SIZE is used as alignment.
2140 PCI-PCI bridge can be specified, if resource
2141 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002142 ecrc= Enable/disable PCIe ECRC (transaction layer
2143 end-to-end CRC checking).
2144 bios: Use BIOS/firmware settings. This is the
2145 the default.
2146 off: Turn ECRC off
2147 on: Turn ECRC on.
Yinghai Lub55438f2012-02-23 19:23:30 -08002148 realloc= Enable/disable reallocating PCI bridge resources
2149 if allocations done by BIOS are too small to
2150 accommodate resources required by all child
2151 devices.
2152 off: Turn realloc off
2153 on: Turn realloc on
2154 realloc same as realloc=on
Rafael J. Wysocki6748dcc2012-03-01 00:06:33 +01002155 noari do not use PCIe ARI.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002156
Chuck Ebberte5665a42008-09-24 20:40:34 -04002157 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2158 Management.
2159 off Disable ASPM.
2160 force Enable ASPM even on devices that claim not to support it.
2161 WARNING: Forcing ASPM on may cause system lockups.
2162
MUNEDA Takahiro7570a332012-02-02 11:09:22 -05002163 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2164 nomsi Do not use MSI for PCI Express Native Hotplug (this
2165 makes all PCIe ports use INTx for hotplug services).
2166
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002167 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002168 auto Ask the BIOS whether or not to use native PCIe services
2169 associated with PCIe ports (PME, hot-plug, AER). Use
2170 them only if that is allowed by the BIOS.
2171 native Use native PCIe services associated with PCIe ports
2172 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002173 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2174 ports driver.
2175
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002176 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002177 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002178 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002179
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180 pcmv= [HW,PCMCIA] BadgePAD 4
2181
2182 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002183 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184
2185 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2186 boot time.
2187 Format: { 0 | 1 }
2188 See arch/parisc/kernel/pdc_chassis.c
2189
Tejun Heof58dc012009-08-14 15:00:50 +09002190 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002191 Currently supported values are "embed" and "page".
2192 Archs may support subset or none of the selections.
2193 See comments in mm/percpu.c for details on each
2194 allocator. This parameter is primarily for debugging
2195 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002196
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002198 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199
2200 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002201 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202
2203 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002204 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205
2206 plip= [PPT,NET] Parallel port network link
2207 Format: { parport<nr> | timid | 0 }
2208 See also Documentation/parport.txt.
2209
Randy Dunlap16290242011-08-13 12:34:52 -07002210 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a2432008-07-12 05:33:30 +02002211 Override pmtimer IOPort with a hex value.
2212 e.g. pmtmr=0x508
2213
Bjorn Helgaas96242112011-08-11 12:14:05 -06002214 pnp.debug=1 [PNP]
2215 Enable PNP debug messages (depends on the
2216 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2217 via /sys/module/pnp/parameters/debug. We always show
2218 current resource usage; turning this on also shows
2219 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002220
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 pnpacpi= [ACPI]
2222 { off }
2223
2224 pnpbios= [ISAPNP]
2225 { on | off | curr | res | no-curr | no-res }
2226
2227 pnp_reserve_irq=
2228 [ISAPNP] Exclude IRQs for the autoconfiguration
2229
2230 pnp_reserve_dma=
2231 [ISAPNP] Exclude DMAs for the autoconfiguration
2232
2233 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002234 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235
2236 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002237 [ISAPNP] Exclude memory regions for the
2238 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239 Ranges are in pairs (memory base and size).
2240
Randy Dunlap4af94f32009-04-17 18:30:28 -07002241 ports= [IP_VS_FTP] IPVS ftp helper module
2242 Default is 21.
2243 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2244 may be specified.
2245 Format: <port>,<port>....
2246
Ingo Molnar45807a12007-07-15 23:40:10 -07002247 print-fatal-signals=
2248 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002249
2250 If enabled, warn about various signal handling
2251 related application anomalies: too many signals,
2252 too many POSIX.1 timers, fatal signals causing a
2253 coredump - etc.
2254
2255 If you hit the warning due to signal overflow,
2256 you might want to try "ulimit -i unlimited".
2257
Ingo Molnar45807a12007-07-15 23:40:10 -07002258 default: off.
2259
Matthew Garrettc22ab332012-03-05 14:59:10 -08002260 printk.always_kmsg_dump=
2261 Trigger kmsg_dump for cases other than kernel oops or
2262 panics
2263 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2264 default: disabled
2265
Randy Dunlape84845c2007-07-15 23:40:25 -07002266 printk.time= Show timing data prefixed to each printk message line
2267 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2268
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002269 processor.max_cstate= [HW,ACPI]
2270 Limit processor to maximum C-state
2271 max_cstate=9 overrides any DMI blacklist limit.
2272
2273 processor.nocst [HW,ACPI]
2274 Ignore the _CST method to determine C-states,
2275 instead using the legacy FADT method
2276
Linus Torvalds1da177e2005-04-16 15:20:36 -07002277 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002278 Format: [schedule,]<number>
2279 Param: "schedule" - profile schedule points.
2280 Param: <number> - step/bucket size as a power of 2 for
2281 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002282 Param: "sleep" - profile D-state sleeping (millisecs).
2283 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002284 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285
Linus Torvalds1da177e2005-04-16 15:20:36 -07002286 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2287 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002288 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289
Randy Dunlapa9913042005-10-23 12:57:11 -07002290 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2291 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2293 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002294 psmouse.resetafter= [HW,MOUSE]
2295 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002296 (0 = never).
2297 psmouse.resolution=
2298 [HW,MOUSE] Set desired mouse resolution, in dpi.
2299 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002300 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 0 = disabled, 1 = enabled (default).
2302
Matthew Garrettdee28e72011-07-21 16:57:55 -04002303 pstore.backend= Specify the name of the pstore backend to use
2304
Linus Torvalds1da177e2005-04-16 15:20:36 -07002305 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002306 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002307
Kay Sieversdc8c8582007-08-15 12:25:38 +02002308 pty.legacy_count=
2309 [KNL] Number of legacy pty's. Overwrites compiled-in
2310 default number.
2311
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002312 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002313
Linus Torvalds1da177e2005-04-16 15:20:36 -07002314 r128= [HW,DRM]
2315
2316 raid= [HW,RAID]
2317 See Documentation/md.txt.
2318
Randy Dunlapa9913042005-10-23 12:57:11 -07002319 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002320 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002321
Linus Torvalds1da177e2005-04-16 15:20:36 -07002322 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002323 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002325 rcupdate.blimit= [KNL,BOOT]
2326 Set maximum number of finished RCU callbacks to process
2327 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002328
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002329 rcupdate.qhimark= [KNL,BOOT]
2330 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002331 RCU callbacks over which batch limiting is disabled.
2332
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002333 rcupdate.qlowmark= [KNL,BOOT]
2334 Set threshold of queued RCU callbacks below which
2335 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002336
Olof Johanssonffdfc402005-09-06 15:17:19 -07002337 rdinit= [KNL]
2338 Format: <full_path>
2339 Run specified binary instead of /init from the ramdisk,
2340 used for early userspace startup. See initrd.
2341
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002342 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002344 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345
Paul Jackson46b6d942008-07-04 10:00:09 -07002346 relax_domain_level=
2347 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002348 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002349
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2351
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002352 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07002353 Format: nn[KMG]
2354 Reserves a hole at the top of the kernel virtual
2355 address space.
2356
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002357 reservelow= [X86]
2358 Format: nn[K]
2359 Set the amount of memory to reserve for BIOS at
2360 the bottom of the address space.
2361
Vivek Goyal7e962872006-09-27 01:50:44 -07002362 reset_devices [KNL] Force drivers to reset the underlying device
2363 during initialization.
2364
Randy Dunlapa9913042005-10-23 12:57:11 -07002365 resume= [SWSUSP]
2366 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002368 resume_offset= [SWSUSP]
2369 Specify the offset from the beginning of the partition
2370 given by "resume=" at which the swap header is located,
2371 in <PAGE_SIZE> units (needed only for swap files).
2372 See Documentation/power/swsusp-and-swap-files.txt
2373
Barry Songf126f732011-10-10 23:38:41 +02002374 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2375 read the resume files
2376
Barry Song6f8d7022011-10-06 20:34:46 +02002377 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2378 Useful for devices that are detected asynchronously
2379 (e.g. USB and MMC devices).
2380
Bojan Smojverf996fc92010-09-09 23:06:23 +02002381 hibernate= [HIBERNATION]
2382 noresume Don't check if there's a hibernation image
2383 present during boot.
2384 nocompress Don't compress/decompress hibernation images.
2385
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002386 retain_initrd [RAM] Keep initrd memory after extraction
2387
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388 rhash_entries= [KNL,NET]
2389 Set number of hash buckets for route cache
2390
2391 riscom8= [HW,SERIAL]
2392 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2393
2394 ro [KNL] Mount root device read-only on boot
2395
2396 root= [KNL] Root filesystem
Will Drewryf2d34fd92011-08-03 16:21:08 -07002397 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398
2399 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2400 mount the root filesystem
2401
2402 rootflags= [KNL] Set root filesystem mount option string
2403
2404 rootfstype= [KNL] Set root filesystem type
2405
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002406 rootwait [KNL] Wait (indefinitely) for root device to show up.
2407 Useful for devices that are detected asynchronously
2408 (e.g. USB and MMC devices).
2409
Linus Torvalds1da177e2005-04-16 15:20:36 -07002410 rw [KNL] Mount root device read-write on boot
2411
2412 S [KNL] Run init in single mode
2413
2414 sa1100ir [NET]
2415 See drivers/net/irda/sa1100_ir.c.
2416
Linus Torvalds1da177e2005-04-16 15:20:36 -07002417 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002418
Mike Travisf6630112009-11-17 18:22:15 -06002419 sched_debug [KNL] Enables verbose scheduler debug messages.
2420
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002421 security= [SECURITY] Choose a security module to enable at boot.
2422 If this boot parameter is not specified, only the first
2423 security module asking for security registration will be
2424 loaded. An invalid security module name will be treated
2425 as if no module has been chosen.
2426
2427 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428 Format: { "0" | "1" }
2429 See security/selinux/Kconfig help text.
2430 0 -- disable.
2431 1 -- enable.
2432 Default value is set via kernel config option.
2433 If enabled at boot time, /selinux/disable can be used
2434 later to disable prior to initial policy load.
2435
John Johansenc1c124e2010-07-29 14:48:09 -07002436 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2437 Format: { "0" | "1" }
2438 See security/apparmor/Kconfig help text
2439 0 -- disable.
2440 1 -- enable.
2441 Default value is set via kernel config option.
2442
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002443 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002444
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 shapers= [NET]
2446 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002447
Yinghai Lub05f78f2008-08-22 01:32:50 -07002448 show_msr= [x86] show boot-time MSR settings
2449 Format: { <integer> }
2450 Show boot-time (BIOS-initialized) MSR settings.
2451 The parameter means the number of CPUs to show,
2452 for example 1 means boot CPU only.
2453
Linus Torvalds1da177e2005-04-16 15:20:36 -07002454 simeth= [IA-64]
2455 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002456
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 slram= [HW,MTD]
2458
David Rientjes3df1ccc2011-10-18 22:09:28 -07002459 slab_max_order= [MM, SLAB]
2460 Determines the maximum allowed order for slabs.
2461 A high setting may cause OOMs due to memory
2462 fragmentation. Defaults to 1 for systems with
2463 more than 32MB of RAM, 0 otherwise.
2464
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002465 slub_debug[=options[,slabs]] [MM, SLUB]
2466 Enabling slub_debug allows one to determine the
2467 culprit if slab objects become corrupted. Enabling
2468 slub_debug can create guard zones around objects and
2469 may poison objects when not in use. Also tracks the
2470 last alloc / free. For more information see
2471 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002472
2473 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002474 Determines the maximum allowed order for slabs.
2475 A high setting may cause OOMs due to memory
2476 fragmentation. For more information see
2477 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002478
2479 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002480 The minimum number of objects per slab. SLUB will
2481 increase the slab order up to slub_max_order to
2482 generate a sufficiently large slab able to contain
2483 the number of objects indicated. The higher the number
2484 of objects the smaller the overhead of tracking slabs
2485 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002486 For more information see Documentation/vm/slub.txt.
2487
2488 slub_min_order= [MM, SLUB]
Masanari Iida24775d62012-02-15 00:26:42 +09002489 Determines the minimum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002490 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002491 For more information see Documentation/vm/slub.txt.
2492
2493 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002494 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002495 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002496 allocs to different slabs. Debug options disable
2497 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002498 For more information see Documentation/vm/slub.txt.
2499
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 smart2= [HW]
2501 Format: <io1>[,<io2>[,...,<io8>]]
2502
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002503 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002504 attempt to substitute SMP alternatives once at boot.
2505
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002506 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2507 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2508 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2509 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2510 smsc-ircc2.ircc_irq= [HW] IRQ line
2511 smsc-ircc2.ircc_dma= [HW] DMA channel
2512 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2513 0: Toshiba Satellite 1800 (GP data pin select)
2514 1: Fast pin select (default)
2515 2: ATC IRMode
2516
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002517 softlockup_panic=
2518 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002519 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002520
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02002522 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523
2524 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002525 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526
2527 spia_io_base= [HW,MTD]
2528 spia_fio_base=
2529 spia_pedr=
2530 spia_peddr=
2531
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002532 stacktrace [FTRACE]
2533 Enabled the stack tracer on boot up.
2534
Steven Rostedt762e1202011-12-19 22:01:00 -05002535 stacktrace_filter=[function-list]
2536 [FTRACE] Limit the functions that the stack tracer
2537 will trace at boot up. function-list is a comma separated
2538 list of functions. This list can be changed at run
2539 time by the stack_trace_filter file in the debugfs
2540 tracing directory. Note, this enables stack tracing
2541 and the stacktrace above is not needed.
2542
Linus Torvalds1da177e2005-04-16 15:20:36 -07002543 sti= [PARISC,HW]
2544 Format: <num>
2545 Set the STI (builtin display/keyboard on the HP-PARISC
2546 machines) console (graphic card) which should be used
2547 as the initial boot-console.
2548 See also comment in drivers/video/console/sticore.c.
2549
2550 sti_font= [HW]
2551 See comment in drivers/video/console/sticore.c.
2552
2553 stifb= [HW]
2554 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2555
Trond Myklebustcbf11072009-08-09 15:06:19 -04002556 sunrpc.min_resvport=
2557 sunrpc.max_resvport=
2558 [NFS,SUNRPC]
2559 SunRPC servers often require that client requests
2560 originate from a privileged port (i.e. a port in the
2561 range 0 < portnr < 1024).
2562 An administrator who wishes to reserve some of these
2563 ports for other uses may adjust the range that the
2564 kernel's sunrpc client considers to be privileged
2565 using these two parameters to set the minimum and
2566 maximum port values.
2567
Greg Banks42a7fc42007-03-06 01:42:23 -08002568 sunrpc.pool_mode=
2569 [NFS]
2570 Control how the NFS server code allocates CPUs to
2571 service thread pools. Depending on how many NICs
2572 you have and where their interrupts are bound, this
2573 option will affect which CPUs will do NFS serving.
2574 Note: this parameter cannot be changed while the
2575 NFS server is running.
2576
2577 auto the server chooses an appropriate mode
2578 automatically using heuristics
2579 global a single global pool contains all CPUs
2580 percpu one pool for each CPU
2581 pernode one pool for each NUMA node (equivalent
2582 to global on non-NUMA machines)
2583
Trond Myklebustcbf11072009-08-09 15:06:19 -04002584 sunrpc.tcp_slot_table_entries=
2585 sunrpc.udp_slot_table_entries=
2586 [NFS,SUNRPC]
2587 Sets the upper limit on the number of simultaneous
2588 RPC calls that can be sent from the client to a
2589 server. Increasing these values may allow you to
2590 improve throughput, but will also increase the
2591 amount of memory reserved for use by the client.
2592
Michal Hockoa42c3902010-11-24 12:57:08 -08002593 swapaccount[=0|1]
2594 [KNL] Enable accounting of swap in memory resource
2595 controller if no parameter or 1 is given or disable
2596 it if 0 is given (See Documentation/cgroups/memory.txt)
2597
Linus Torvalds1da177e2005-04-16 15:20:36 -07002598 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002599
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600 switches= [HW,M68k]
2601
Andi Kleene52eec12010-09-08 16:54:17 +02002602 sysfs.deprecated=0|1 [KNL]
2603 Enable/disable old style sysfs layout for old udev
2604 on older distributions. When this option is enabled
2605 very new udev will not work anymore. When this option
2606 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2607 in older udev will not work anymore.
2608 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2609 the kernel configuration.
2610
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002611 sysrq_always_enabled
2612 [KNL]
2613 Ignore sysrq setting - this boot parameter will
2614 neutralize any effect of /proc/sys/kernel/sysrq.
2615 Useful for debugging.
2616
Linus Torvalds1da177e2005-04-16 15:20:36 -07002617 tdfx= [HW,DRM]
2618
David Brownell77437fd2008-07-23 21:28:33 -07002619 test_suspend= [SUSPEND]
2620 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2621 standby suspend) as the system sleep state to briefly
2622 enter during system startup. The system is woken from
2623 this state using a wakeup-capable RTC alarm.
2624
Linus Torvalds1da177e2005-04-16 15:20:36 -07002625 thash_entries= [KNL,NET]
2626 Set number of hash buckets for TCP connection
2627
Len Brownf8707ec2007-08-12 00:12:54 -04002628 thermal.act= [HW,ACPI]
2629 -1: disable all active trip points in all thermal zones
2630 <degrees C>: override all lowest active trip points
2631
Len Brownc52a7412007-08-14 15:49:32 -04002632 thermal.crt= [HW,ACPI]
2633 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002634 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002635
Len Brownf5487142007-08-12 00:12:44 -04002636 thermal.nocrt= [HW,ACPI]
2637 Set to disable actions on ACPI thermal zone
2638 critical and hot trip points.
2639
Len Brown72b33ef2007-08-12 00:12:17 -04002640 thermal.off= [HW,ACPI]
2641 1: disable ACPI thermal control
2642
Len Browna70cdc52007-08-12 00:12:35 -04002643 thermal.psv= [HW,ACPI]
2644 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002645 <degrees C>: override all passive trip points to this
2646 value
Len Browna70cdc52007-08-12 00:12:35 -04002647
Len Brown730ff342007-08-12 00:12:26 -04002648 thermal.tzp= [HW,ACPI]
2649 Specify global default ACPI thermal zone polling rate
2650 <deci-seconds>: poll all this frequency
2651 0: no polling (default)
2652
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002653 threadirqs [KNL]
2654 Force threading of all interrupt handlers except those
Masanari Iida24775d62012-02-15 00:26:42 +09002655 marked explicitly IRQF_NO_THREAD.
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002656
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002657 topology= [S390]
2658 Format: {off | on}
2659 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002660 topology information if the hardware supports this.
2661 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002662 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002663 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002664
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665 tp720= [HW,PS2]
2666
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002667 tpm_suspend_pcr=[HW,TPM]
2668 Format: integer pcr id
2669 Specify that at suspend time, the tpm driver
2670 should extend the specified pcr with zeros,
2671 as a workaround for some chips which fail to
2672 flush the last written pcr on TPM_SaveState.
2673 This will guarantee that all the other pcrs
2674 are saved.
2675
Li Zefan9d612be2009-06-24 17:33:15 +08002676 trace_buf_size=nn[KMG]
2677 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002678
Li Zefan020e5f82009-07-01 10:47:05 +08002679 trace_event=[event-list]
2680 [FTRACE] Set and start specified trace events in order
2681 to facilitate early boot debugging.
2682 See also Documentation/trace/events.txt
2683
Jiri Kosinafcf4d822012-03-21 16:34:02 -07002684 transparent_hugepage=
2685 [KNL]
2686 Format: [always|madvise|never]
2687 Can be used to control the default behavior of the system
2688 with respect to transparent hugepages.
2689 See Documentation/vm/transhuge.txt for more details.
2690
john stultzd3b8f882009-08-17 16:40:47 -07002691 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002692 Format: <string>
2693 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002694 disables clocksource verification at runtime, as well
2695 as the stability checks done at bootup. Used to enable
2696 high-resolution timer mode on older hardware, and in
2697 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002698 [x86] noirqtime: Do not use TSC to do irq accounting.
2699 Used to run time disable IRQ_TIME_ACCOUNTING on any
2700 platforms where RDTSC is slow and this accounting
2701 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002702
Randy Dunlapa9913042005-10-23 12:57:11 -07002703 turbografx.map[2|3]= [HW,JOY]
2704 TurboGraFX parallel port interface
2705 Format:
2706 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002707 See also Documentation/input/joystick-parport.txt
2708
Christian Kujaub6935f82011-05-31 15:22:05 +00002709 udbg-immortal [PPC] When debugging early kernel crashes that
2710 happen after console_init() and before a proper
2711 console driver takes over, this boot options might
2712 help "seeing" what's going on.
2713
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002714 uhash_entries= [KNL,NET]
2715 Set number of hash buckets for UDP/UDP-Lite connections
2716
Alan Stern5f8364b2006-12-05 16:29:55 -05002717 uhci-hcd.ignore_oc=
2718 [USB] Ignore overcurrent events (default N).
2719 Some badly-designed motherboards generate lots of
2720 bogus events, for ports that aren't wired to
2721 anything. Set this parameter to avoid log spamming.
2722 Note that genuine overcurrent events won't be
2723 reported either.
2724
Simon Arlotte3a61b02008-07-19 23:32:54 +01002725 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002726 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01002727
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02002728 usbcore.authorized_default=
2729 [USB] Default USB device authorization:
2730 (default -1 = authorized except for wireless USB,
2731 0 = not authorized, 1 = authorized)
2732
Alan Sternb5e795f2007-02-20 15:00:53 -05002733 usbcore.autosuspend=
2734 [USB] The autosuspend time delay (in seconds) used
2735 for newly-detected USB devices (default 2). This
2736 is the time required before an idle device will be
2737 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002738 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002739
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002740 usbcore.usbfs_snoop=
2741 [USB] Set to log all usbfs traffic (default 0 = off).
2742
2743 usbcore.blinkenlights=
2744 [USB] Set to cycle leds on hubs (default 0 = off).
2745
2746 usbcore.old_scheme_first=
2747 [USB] Start with the old device initialization
2748 scheme (default 0 = off).
2749
Alan Stern3f5eb8d2011-11-17 16:41:35 -05002750 usbcore.usbfs_memory_mb=
2751 [USB] Memory limit (in MB) for buffers allocated by
2752 usbfs (default = 16, 0 = max = 2047).
2753
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002754 usbcore.use_both_schemes=
2755 [USB] Try the other device initialization scheme
2756 if the first one fails (default 1 = enabled).
2757
2758 usbcore.initial_descriptor_timeout=
2759 [USB] Specifies timeout for the initial 64-byte
2760 USB_REQ_GET_DESCRIPTOR request in milliseconds
2761 (default 5000 = 5.0 seconds).
2762
Linus Torvalds1da177e2005-04-16 15:20:36 -07002763 usbhid.mousepoll=
2764 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002765
Alan Sternd4f373e2008-11-10 14:07:45 -05002766 usb-storage.delay_use=
2767 [UMS] The delay in seconds before a new device is
2768 scanned for Logical Units (default 5).
2769
2770 usb-storage.quirks=
2771 [UMS] A list of quirks entries to supplement or
2772 override the built-in unusual_devs list. List
2773 entries are separated by commas. Each entry has
2774 the form VID:PID:Flags where VID and PID are Vendor
2775 and Product ID values (4-digit hex numbers) and
2776 Flags is a set of characters, each corresponding
2777 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002778 a = SANE_SENSE (collect more than 18 bytes
2779 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05002780 b = BAD_SENSE (don't collect more than 18
2781 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002782 c = FIX_CAPACITY (decrease the reported
2783 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01002784 d = NO_READ_DISC_INFO (don't use
2785 READ_DISC_INFO command);
2786 e = NO_READ_CAPACITY_16 (don't use
2787 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05002788 h = CAPACITY_HEURISTICS (decrease the
2789 reported device capacity by one
2790 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002791 i = IGNORE_DEVICE (don't bind to this
2792 device);
2793 l = NOT_LOCKABLE (don't try to lock and
2794 unlock ejectable media);
2795 m = MAX_SECTORS_64 (don't transfer more
2796 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04002797 n = INITIAL_READ10 (force a retry of the
2798 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05002799 o = CAPACITY_OK (accept the capacity
2800 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002801 r = IGNORE_RESIDUE (the device reports
2802 bogus residue values);
2803 s = SINGLE_LUN (the device has only one
2804 Logical Unit);
2805 w = NO_WP_DETECT (don't test whether the
2806 medium is write-protected).
2807 Example: quirks=0419:aaf5:rl,0421:0433:rc
2808
Stephen Boydac1667d2011-08-13 12:34:50 -07002809 user_debug= [KNL,ARM]
2810 Format: <int>
2811 See arch/arm/Kconfig.debug help text.
2812 1 - undefined instruction events
2813 2 - system calls
2814 4 - invalid data aborts
2815 8 - SIGSEGV faults
2816 16 - SIGBUS faults
2817 Example: user_debug=31
2818
Ian Campbell14315592010-02-17 10:38:10 +00002819 userpte=
2820 [X86] Flags controlling user PTE allocations.
2821
2822 nohigh = do not allocate PTE pages in
2823 HIGHMEM regardless of setting
2824 of CONFIG_HIGHPTE.
2825
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302826 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002827 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002828 vdso=1: enable VDSO (default)
2829 vdso=0: disable VDSO mapping
2830
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302831 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002832 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2833 vdso32=1: enable 32-bit VDSO (default)
2834 vdso32=0: disable 32-bit VDSO mapping
2835
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002836 vector= [IA-64,SMP]
2837 vector=percpu: enable percpu vector domain
2838
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839 video= [FB] Frame buffer configuration
2840 See Documentation/fb/modedb.txt.
2841
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002842 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002843 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002844 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845 Use vga=ask for menu.
2846 This is actually a boot loader parameter; the value is
2847 passed to the kernel using a special protocol.
2848
Randy Dunlapa9913042005-10-23 12:57:11 -07002849 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002850 size of <nn>. This can be used to increase the
2851 minimum size (128MB on x86). It can also be used to
2852 decrease the size and leave more room for directly
2853 mapped kernel RAM.
2854
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002855 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2856 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002857
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002858 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2859 Format: <command>
2860
2861 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2862 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002863
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002864 vsyscall= [X86-64]
2865 Controls the behavior of vsyscalls (i.e. calls to
2866 fixed addresses of 0xffffffffff600x00 from legacy
2867 code). Most statically-linked binaries and older
2868 versions of glibc use these calls. Because these
2869 functions are at fixed addresses, they make nice
2870 targets for exploits that can control RIP.
2871
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08002872 emulate [default] Vsyscalls turn into traps and are
2873 emulated reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002874
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08002875 native Vsyscalls are native syscall instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04002876 This is a little bit faster than trapping
2877 and makes a few dynamic recompilers work
2878 better than they would in emulation mode.
2879 It also makes exploits much easier to write.
2880
2881 none Vsyscalls don't work at all. This makes
2882 them quite hard to use for exploits but
2883 might break your system.
2884
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08002885 vt.cur_default= [VT] Default cursor shape.
2886 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2887 the parameters of the <Esc>[?A;B;Cc escape sequence;
2888 see VGA-softcursor.txt. Default: 2 = underline.
2889
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002890 vt.default_blu= [VT]
2891 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2892 Change the default blue palette of the console.
2893 This is a 16-member array composed of values
2894 ranging from 0-255.
2895
2896 vt.default_grn= [VT]
2897 Format: <green0>,<green1>,<green2>,...,<green15>
2898 Change the default green palette of the console.
2899 This is a 16-member array composed of values
2900 ranging from 0-255.
2901
2902 vt.default_red= [VT]
2903 Format: <red0>,<red1>,<red2>,...,<red15>
2904 Change the default red palette of the console.
2905 This is a 16-member array composed of values
2906 ranging from 0-255.
2907
2908 vt.default_utf8=
2909 [VT]
2910 Format=<0|1>
2911 Set system-wide default UTF-8 mode for all tty's.
2912 Default is 1, i.e. UTF-8 mode is enabled for all
2913 newly opened terminals.
2914
Matthew Garrettf6c06b62009-11-13 15:14:11 -05002915 vt.global_cursor_default=
2916 [VT]
2917 Format=<-1|0|1>
2918 Set system-wide default for whether a cursor
2919 is shown on new VTs. Default is -1,
2920 i.e. cursors will be created by default unless
2921 overridden by individual drivers. 0 will hide
2922 cursors, 1 will display them.
2923
Randy Dunlap4724ba572010-05-03 11:42:52 -07002924 watchdog timers [HW,WDT] For information on watchdog timers,
2925 see Documentation/watchdog/watchdog-parameters.txt
2926 or other driver-specific files in the
2927 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002928
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002929 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2930 default x2apic cluster mode on platforms
2931 supporting x2apic.
2932
Jacob Panbb24c472009-09-02 07:37:17 -07002933 x86_mrst_timer= [X86-32,APBT]
2934 Choose timer option for x86 Moorestown MID platform.
2935 Two valid options are apbt timer only and lapic timer
2936 plus one apbt timer for broadcast timer.
2937 x86_mrst_timer=apbt_only | lapic_and_apbt
2938
Linus Torvalds1da177e2005-04-16 15:20:36 -07002939 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2940 xd_geo= See header of drivers/block/xd.c.
2941
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002942 xen_emul_unplug= [HW,X86,XEN]
2943 Unplug Xen emulated devices
2944 Format: [unplug0,][unplug1]
2945 ide-disks -- unplug primary master IDE devices
2946 aux-ide-disks -- unplug non-primary-master IDE devices
2947 nics -- unplug network devices
2948 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01002949 unnecessary -- unplugging emulated devices is
2950 unnecessary even if the host did not respond to
2951 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01002952 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01002953
Linus Torvalds1da177e2005-04-16 15:20:36 -07002954 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002955 Format:
2956 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002957
Randy Dunlapa9913042005-10-23 12:57:11 -07002958______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002959
2960TODO:
2961
Linus Torvalds1da177e2005-04-16 15:20:36 -07002962 Add more DRM drivers.