blob: 4609e81dbc37fc2dbfa005ff607890df3a8bbc6b [file] [log] [blame]
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 MDA MDA console support is enabled.
Randy Dunlap16290242011-08-13 12:34:52 -070074 MIPS MIPS architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070076 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070077 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 NET Appropriate network support is enabled.
79 NUMA NUMA support is enabled.
80 NFS Appropriate NFS support is enabled.
81 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070082 PV_OPS A paravirtualized kernel is enabled.
83 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 PARISC The PA-RISC architecture is enabled.
85 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070086 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 PCMCIA The PCMCIA subsystem is enabled.
88 PNP Plug & Play support is enabled.
89 PPC PowerPC architecture is enabled.
90 PPT Parallel port support is enabled.
91 PS2 Appropriate PS/2 support is enabled.
92 RAM RAM disk support is enabled.
93 S390 S390 architecture is enabled.
94 SCSI Appropriate SCSI support is enabled.
Randy Dunlap163475f2010-08-14 12:36:14 -070095 A lot of drivers have their options described inside
96 the Documentation/scsi/ sub-directory.
James Morris20510f22007-10-16 23:31:32 -070097 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 SELINUX SELinux support is enabled.
John Johansenc1c124e2010-07-29 14:48:09 -070099 APPARMOR AppArmor support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +0900101 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 SMP The kernel is an SMP kernel.
103 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -0700104 SWSUSP Software suspend (hibernation) is enabled.
105 SUSPEND System suspend states are enabled.
Rajiv Andrade225a9be2010-03-25 00:55:32 -0300106 TPM TPM drivers are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500108 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 USB USB support is enabled.
110 USBHID USB Human Interface Device support is enabled.
111 V4L Video For Linux support is enabled.
Pawel Moll81a054c2012-05-09 18:30:16 +0100112 VMMIO Driver for memory mapped virtio devices is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 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
Shuah Khanc099cf12012-05-24 15:58:25 -0600338 amd_iommu_dump= [HW,X86-64]
339 Enable AMD IOMMU driver option to dump the ACPI table
340 for AMD IOMMU. With this option enabled, AMD IOMMU
341 driver will print ACPI tables for AMD IOMMU during
342 IOMMU initialization.
343
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 amijoy.map= [HW,JOY] Amiga joystick support
345 Map of devices attached to JOY0DAT and JOY1DAT
346 Format: <a>,<b>
Paul Bolle395cf962011-08-15 02:02:26 +0200347 See also Documentation/input/joystick.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348
349 analog.map= [HW,JOY] Analog joystick and gamepad support
350 Specifies type or capabilities of an analog joystick
351 connected to one of 16 gameports
352 Format: <type1>,<type2>,..<type16>
353
Randy Dunlapa9913042005-10-23 12:57:11 -0700354 apc= [HW,SPARC]
355 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 Format: noidle
357 Disable APC CPU standby support. SPARCstation-Fox does
358 not play well with APC CPU idle - disable it if you have
359 APC and your system crashes randomly.
360
Randy Dunlapca1eda22009-05-06 16:02:58 -0700361 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700362 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 Format: { quiet (default) | verbose | debug }
364 Change the amount of debugging information output
365 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700366
Brian Haleyb0f83b22010-02-04 13:36:50 -0800367 autoconf= [IPV6]
368 See Documentation/networking/ipv6.txt.
369
Cyrill Gorcunov9636bc02009-10-14 19:09:04 +0400370 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
371 Limit apic dumping. The parameter defines the maximal
372 number of local apics being dumped. Also it is possible
373 to set it to "all" by meaning -- no limit here.
374 Format: { 1 (default) | 2 | ... | all }.
375 The parameter valid if only apic=debug or
376 apic=verbose is specified.
377 Example: apic=debug show_lapic=all
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700380 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
383 Format: <io>,<irq>,<nodeID>
384
385 ataflop= [HW,M68k]
386
387 atarimouse= [HW,MOUSE] Atari Mouse
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
390 EzKey and similar keyboards
391
392 atkbd.reset= [HW] Reset keyboard during initialization
393
Randy Dunlapa9913042005-10-23 12:57:11 -0700394 atkbd.set= [HW] Select keyboard code set
395 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
397 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
398 keyboards
399
400 atkbd.softraw= [HW] Choose between synthetic and real raw mode
401 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700402
403 atkbd.softrepeat= [HW]
404 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 baycom_epp= [HW,AX25]
407 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700408
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
410 Format: <io>,<mode>
411 See header of drivers/net/hamradio/baycom_par.c.
412
Randy Dunlapa9913042005-10-23 12:57:11 -0700413 baycom_ser_fdx= [HW,AX25]
414 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 Format: <io>,<irq>,<mode>[,<baud>]
416 See header of drivers/net/hamradio/baycom_ser_fdx.c.
417
Randy Dunlapa9913042005-10-23 12:57:11 -0700418 baycom_ser_hdx= [HW,AX25]
419 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 Format: <io>,<irq>,<mode>
421 See header of drivers/net/hamradio/baycom_ser_hdx.c.
422
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700423 boot_delay= Milliseconds to delay each printk during boot.
424 Values larger than 10 seconds (10000) are changed to
425 no delay (0).
426 Format: integer
427
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700428 bootmem_debug [KNL] Enable bootmem allocator debug messages.
429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700431 bttv.radio= Most important insmod options are available as
432 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
Paul Bolle395cf962011-08-15 02:02:26 +0200434 bttv.tuner=
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435
Will Schmidt4e89a2d2010-09-28 15:33:12 +0000436 bulk_remove=off [PPC] This parameter disables the use of the pSeries
437 firmware feature for flushing multiple hpte entries
438 at a time.
439
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 c101= [NET] Moxa C101 synchronous serial card
441
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700442 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 Sometimes CPU hardware bugs make them report the cache
444 size incorrectly. The kernel will attempt work arounds
445 to fix known problems, but for some CPUs it is not
446 possible to determine what the correct size should be.
447 This option provides an override for these situations.
448
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100449 ccw_timeout_log [S390]
450 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451
Paul Menage8bab8dd2008-04-04 14:29:57 -0700452 cgroup_disable= [KNL] Disable a particular controller
453 Format: {name of the controller(s) to disable}
454 {Currently supported controllers - "memory"}
455
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 checkreqprot [SELINUX] Set initial checkreqprot flag value.
457 Format: { "0" | "1" }
458 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700459 0 -- check protection applied by kernel (includes
460 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 1 -- check protection requested by application.
462 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700463 Value can be changed at runtime via
464 /selinux/checkreqprot.
465
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100466 cio_ignore= [S390]
467 See Documentation/s390/CommonIO for details.
468
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700469 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700470 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200471 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700472 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200473 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 Format: { pit | tsc | cyclone | pmtmr }
475
John Stultz592913e2010-07-13 17:56:20 -0700476 clocksource= Override the default clocksource
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700477 Format: <string>
478 Override the default clocksource and use the clocksource
479 with the name specified.
480 Some clocksource names to choose from, depending on
481 the platform:
482 [all] jiffies (this is the base, fallback clocksource)
483 [ACPI] acpi_pm
484 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
485 pxa_timer,timer3,32k_counter,timer0_1
486 [AVR32] avr32
Alok Kataria9863c902010-08-23 14:49:11 -0700487 [X86-32] pit,hpet,tsc;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700488 scx200_hrt on Geode; cyclone on IBM x440
489 [MIPS] MIPS
490 [PARISC] cr16
491 [S390] tod
492 [SH] SuperH
493 [SPARC64] tick
494 [X86-64] hpet,tsc
495
Andi Kleenac72e782008-01-30 13:33:21 +0100496 clearcpuid=BITNUM [X86]
497 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800498 arch/x86/include/asm/cpufeature.h for the valid bit
499 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100500 stable over kernel options, but the vendor specific
501 ones should be.
502 Also note that user programs calling CPUID directly
503 or using the feature without checking anything
504 will still see it. This just prevents it from
505 being used by the kernel or shown in /proc/cpuinfo.
506 Also note the kernel might malfunction if you disable
507 some critical bits.
508
Marek Szyprowskic64be2b2011-12-29 13:09:51 +0100509 cma=nn[MG] [ARM,KNL]
510 Sets the size of kernel global memory area for contiguous
511 memory allocations. For more information, see
512 include/linux/dma-contiguous.h
513
Robert Jennings14f966e2009-04-15 05:55:32 +0000514 cmo_free_hint= [PPC] Format: { yes | no }
515 Specify whether pages are marked as being inactive
516 when they are freed. This is used in CMO environments
517 to determine OS memory pressure for page stealing by
518 a hypervisor.
519 Default: yes
520
Marek Szyprowskic7909502011-12-29 13:09:51 +0100521 coherent_pool=nn[KMG] [ARM,KNL]
522 Sets the size of memory pool for coherent, atomic dma
Marek Szyprowskie9da6e92012-07-30 09:11:33 +0200523 allocations, by default set to 256K.
Marek Szyprowskic7909502011-12-29 13:09:51 +0100524
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530525 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100526 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100527 Range: 0 - 8192
528 Default: 64
529
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700531 Format:
532 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533
534 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
535 Format: <io>[,<irq>]
536
Randy Dunlapa9913042005-10-23 12:57:11 -0700537 com90xx= [HW,NET]
538 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 Format: <io>[,<irq>[,<memstart>]]
540
541 condev= [HW,S390] console device
542 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 console= [KNL] Output console device and options.
545
546 tty<n> Use the virtual console device <n>.
547
548 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800549 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800551 the form "bbbbpnf", where "bbbb" is the baud rate,
552 "p" is parity ("n", "o", or "e"), "n" is number of
553 bits, and "f" is flow control ("r" for RTS or
554 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800556 See Documentation/serial-console.txt for more
557 information. See
558 Documentation/networking/netconsole.txt for an
559 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700561 uart[8250],io,<addr>[,options]
562 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 Start an early, polled-mode console on the 8250/16550
564 UART at the specified I/O port or MMIO address,
565 switching to the matching ttyS device later. The
566 options are the same as for ttyS, above.
Konrad Rzeszutek Wilka2fd6412013-02-25 15:54:09 -0500567 hvc<n> Use the hypervisor console device <n>. This is for
568 both Xen and PowerPC hypervisors.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700570 If the device connected to the port is not a TTY but a braille
571 device, prepend "brl," before the device type, for instance
572 console=brl,ttyS0
573 For now, only VisioBraille is supported.
574
Daniel Mackf324edc2009-06-16 15:33:52 -0700575 consoleblank= [KNL] The console blank (screen saver) timeout in
576 seconds. Defaults to 10*60 = 10mins. A value of 0
577 disables the blank timer.
578
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800579 coredump_filter=
580 [KNL] Change the default value for
581 /proc/<pid>/coredump_filter.
582 See also Documentation/filesystems/proc.txt.
583
Len Brown62027ae2011-04-01 18:13:10 -0400584 cpuidle.off=1 [CPU_IDLE]
585 disable the cpuidle sub-system
586
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700588 Format:
589 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800591 crashkernel=size[KMG][@offset[KMG]]
592 [KNL] Using kexec, Linux can switch to a 'crash kernel'
593 upon panic. This parameter reserves the physical
594 memory region [offset, offset + size] for that kernel
595 image. If '@offset' is omitted, then a suitable offset
596 is selected automatically. Check
597 Documentation/kdump/kdump.txt for further details.
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700598
Yinghai Lu0212f912013-01-24 12:20:11 -0800599 crashkernel_low=size[KMG]
600 [KNL, x86] parts under 4G.
601
Bernhard Wallefb391592007-10-18 23:41:02 -0700602 crashkernel=range1:size1[,range2:size2,...][@offset]
603 [KNL] Same as above, but depends on the memory
604 in the running system. The syntax of range is
605 start-[end] where start and end are both
606 a memory unit (amount[KMG]). See also
Ahmed S. Darwish6f21e642011-02-20 20:08:35 -0800607 Documentation/kdump/kdump.txt for an example.
Bernhard Wallefb391592007-10-18 23:41:02 -0700608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 cs89x0_dma= [HW,NET]
610 Format: <dma>
611
612 cs89x0_media= [HW,NET]
613 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700614
Randy Dunlapa9913042005-10-23 12:57:11 -0700615 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 See header of drivers/s390/block/dasd_devmap.c.
617
618 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
619 (one device per port)
620 Format: <port#>,<type>
621 See also Documentation/input/joystick-parport.txt
622
Thomas Renningera648ec02010-08-06 16:11:02 +0200623 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
624 time. See Documentation/dynamic-debug-howto.txt for
Jim Cromie29e36c92012-04-27 14:30:41 -0600625 details. Deprecated, see dyndbg.
Thomas Renningera648ec02010-08-06 16:11:02 +0200626
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 debug [KNL] Enable kernel debugging (events log level).
628
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700629 debug_locks_verbose=
630 [KNL] verbose self-tests
631 Format=<0|1>
632 Print debugging info while doing the locking API
633 self-tests.
634 We default to 0 (no extra messages), setting it to
635 1 will print _a lot_ more information - normally
636 only useful to kernel developers.
637
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700638 debug_objects [KNL] Enable object debugging
639
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500640 no_debug_objects
641 [KNL] Disable object debugging
642
Stanislaw Gruszkac0a32fc52012-01-10 15:07:28 -0800643 debug_guardpage_minorder=
644 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
645 parameter allows control of the order of pages that will
646 be intentionally kept free (and hence protected) by the
647 buddy allocator. Bigger value increase the probability
648 of catching random memory corruption, but reduce the
649 amount of memory for normal system use. The maximum
650 possible value is MAX_ORDER/2. Setting this parameter
651 to 1 or 2 should be enough to identify most random
652 memory corruption problems caused by bugs in kernel or
653 driver code when a CPU writes to (or reads from) a
654 random memory location. Note that there exists a class
655 of memory corruptions problems caused by buggy H/W or
656 F/W or by drivers badly programing DMA (basically when
657 memory is written at bus level and the CPU MMU is
658 bypassed) which are not detectable by
659 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
660 tracking down these problems.
661
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200662 debugpat [X86] Enable PAT debugging
663
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200664 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 Format: <area>[,<node>]
666 See also Documentation/networking/decnet.txt.
667
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700668 default_hugepagesz=
669 [same as hugepagesz=] The size of the default
670 HugeTLB page size. This is the size represented by
671 the legacy /proc/ hugepages APIs, used for SHM, and
672 default size when mounting hugetlbfs filesystems.
673 Defaults to the default architecture's huge page size
674 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 dhash_entries= [KNL]
677 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700678
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 digi= [HW,SERIAL]
680 IO parameters + enable/disable command.
681
682 digiepca= [HW,SERIAL]
683 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000684 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685
Brian Haleyb0f83b22010-02-04 13:36:50 -0800686 disable= [IPV6]
687 See Documentation/networking/ipv6.txt.
688
Nishanth Aravamudan4e8b0cf2011-02-10 09:10:47 +0000689 disable_ddw [PPC/PSERIES]
690 Disable Dynamic DMA Window support. Use this if
691 to workaround buggy firmware.
692
Brian Haleyb0f83b22010-02-04 13:36:50 -0800693 disable_ipv6= [IPV6]
694 See Documentation/networking/ipv6.txt.
695
Yinghai Lu95ffa242008-04-29 03:52:33 -0700696 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700697 The kernel tries to adjust MTRR layout from continuous
698 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700699 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700700
Yinghai Lu093af8d2008-01-30 13:33:32 +0100701 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100702 By default the kernel will trim any uncacheable
703 memory out of your available memory pool based on
704 MTRR settings. This parameter disables that behavior,
705 possibly causing your machine to run very slowly.
706
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530707 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700708 Disable PIN 1 of APIC timer
709 Can be useful to work around chipset bugs.
710
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700711 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
712 this option disables the debugging code at boot.
713
714 dma_debug_entries=<number>
715 This option allows to tune the number of preallocated
716 entries for DMA-API debugging code. One entry is
717 required per DMA-API allocation. Use this if the
718 DMA-API debugging code disables itself because the
719 architectural default is too low.
720
Joerg Roedel1745de52009-05-22 21:49:51 +0200721 dma_debug_driver=<driver_name>
722 With this option the DMA-API debugging driver
723 filter feature can be enabled at boot time. Just
724 pass the driver to filter for as the parameter.
725 The filter can be disabled or changed to another
726 driver later using sysfs.
727
Carsten Emdeda0df922012-03-18 22:37:33 +0100728 drm_kms_helper.edid_firmware=[<connector>:]<file>
729 Broken monitors, graphic adapters and KVMs may
730 send no or incorrect EDID data sets. This parameter
731 allows to specify an EDID data set in the
732 /lib/firmware directory that is used instead.
733 Generic built-in EDID data sets are used, if one of
734 edid/1024x768.bin, edid/1280x1024.bin,
735 edid/1680x1050.bin, or edid/1920x1080.bin is given
736 and no file with the same name exists. Details and
737 instructions how to build your own EDID data are
738 available in Documentation/EDID/HOWTO.txt. An EDID
739 data set will only be used for a particular connector,
740 if its name and a colon are prepended to the EDID
741 name.
742
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 dscc4.setup= [NET]
744
Jim Cromie29e36c92012-04-27 14:30:41 -0600745 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
746 module.dyndbg[="val"]
747 Enable debug messages at boot time. See
748 Documentation/dynamic-debug-howto.txt for details.
749
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700750 earlycon= [KNL] Output early console device and options.
751 uart[8250],io,<addr>[,options]
752 uart[8250],mmio,<addr>[,options]
Samium Gromoff1917ac72010-07-20 15:26:51 -0700753 uart[8250],mmio32,<addr>[,options]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700754 Start an early, polled-mode console on the 8250/16550
755 UART at the specified I/O port or MMIO address.
Randy Dunlap16290242011-08-13 12:34:52 -0700756 MMIO inter-register address stride is either 8-bit
757 (mmio) or 32-bit (mmio32).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700758 The options are the same as for ttyS, above.
759
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530760 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 earlyprintk=vga
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -0500762 earlyprintk=xen
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 earlyprintk=serial[,ttySn[,baudrate]]
Jason Wesselea3acb12009-09-24 09:08:30 -0500764 earlyprintk=ttySn[,baudrate]
Jason Wessel9780bc42009-08-20 15:39:57 -0500765 earlyprintk=dbgp[debugController#]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766
Randy Dunlapa9913042005-10-23 12:57:11 -0700767 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 takes over.
769
Yinghai Lu5c059172008-07-24 17:29:40 -0700770 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771
772 Currently only ttyS0 and ttyS1 are supported.
773
774 Interaction with the standard serial driver is not
775 very good.
776
777 The VGA output is eventually overwritten by the real
778 console.
779
Konrad Rzeszutek Wilk2482a922013-02-25 15:54:08 -0500780 The xen output can only be used by Xen PV guests.
781
Jason Wessel97311912010-05-20 21:04:30 -0500782 ekgdboc= [X86,KGDB] Allow early kernel console debugging
783 ekgdboc=kbd
784
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300785 This is designed to be used in conjunction with
Jason Wessel97311912010-05-20 21:04:30 -0500786 the boot argument: earlyprintk=vga
787
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700789 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 eisa_irq_edge= [PARISC,HW]
792 See header of drivers/parisc/eisa.c.
793
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700794 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700796 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
798 elevator= [IOSCHED]
Randy Dunlap17a9e7b2010-11-11 12:09:59 +0100799 Format: {"cfq" | "deadline" | "noop"}
Paul Bolle395cf962011-08-15 02:02:26 +0200800 See Documentation/block/cfq-iosched.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -0700801 Documentation/block/deadline-iosched.txt for details.
802
Michael Holzheud3bf37952011-10-30 15:16:37 +0100803 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Randy Dunlapa9913042005-10-23 12:57:11 -0700804 Specifies physical address of start of kernel core
Michael Holzheud3bf37952011-10-30 15:16:37 +0100805 image elf header and optionally the size. Generally
806 kexec loader will pass this option to capture kernel.
Vivek Goyalaac04b32006-01-09 20:51:47 -0800807 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700809 enable_mtrr_cleanup [X86]
810 The kernel tries to adjust MTRR layout from continuous
811 to discrete, to make X server driver able to add WB
812 entry later. This parameter enables that.
813
Randy Dunlapca1eda22009-05-06 16:02:58 -0700814 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700815 Enable PIN 1 of APIC timer
816 Can be useful to work around chipset bugs
817 (in particular on some ATI chipsets).
818 The kernel tries to set a reasonable default.
819
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 enforcing [SELINUX] Set initial enforcing status.
821 Format: {"0" | "1"}
822 See security/selinux/Kconfig help text.
823 0 -- permissive (log only, no denials).
824 1 -- enforcing (deny and log).
825 Default value is 0.
826 Value can be changed at runtime via /selinux/enforce.
827
Huang Yinga08f82d2010-05-18 14:35:21 +0800828 erst_disable [ACPI]
829 Disable Error Record Serialization Table (ERST)
830 support.
831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 ether= [HW,NET] Ethernet cards parameters
833 This option is obsoleted by the "netdev=" option, which
834 has equivalent usage. See its documentation for details.
835
Mimi Zohar7102ebc2011-05-12 18:33:20 -0400836 evm= [EVM]
837 Format: { "fix" }
838 Permit 'security.evm' to be updated regardless of
839 current integrity status.
840
Akinobu Mitade1ba092006-12-08 02:39:42 -0800841 failslab=
842 fail_page_alloc=
843 fail_make_request=[KNL]
844 General fault injection mechanism.
845 Format: <interval>,<probability>,<space>,<times>
Paul Bolle395cf962011-08-15 02:02:26 +0200846 See also Documentation/fault-injection/.
Akinobu Mitade1ba092006-12-08 02:39:42 -0800847
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000849 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
Alex Chiangf13ae302008-05-08 14:03:23 -0600851 force_pal_cache_flush
852 [IA-64] Avoid check_sal_cache_flush which may hang on
853 buggy SAL_CACHE_FLUSH implementations. Using this
854 parameter will force ia64_sal_cache_flush to call
855 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
856
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100857 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400858 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100859 as early as possible in order to facilitate early
860 boot debugging.
861
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200862 ftrace_dump_on_oops[=orig_cpu]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400863 [FTRACE] will dump the trace buffers on oops.
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200864 If no parameter is passed, ftrace will dump
865 buffers of all CPUs, but if you pass orig_cpu, it will
866 dump only the buffer of the CPU that triggered the
867 oops.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400868
869 ftrace_filter=[function-list]
870 [FTRACE] Limit the functions traced by the function
871 tracer at boot up. function-list is a comma separated
872 list of functions. This list can be changed at run
873 time by the set_ftrace_filter file in the debugfs
Randy Dunlap16290242011-08-13 12:34:52 -0700874 tracing directory.
Steven Rostedt2af15d62009-05-28 13:37:24 -0400875
876 ftrace_notrace=[function-list]
877 [FTRACE] Do not trace the functions specified in
878 function-list. This list can be changed at run time
879 by the set_ftrace_notrace file in the debugfs
880 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100881
Stefan Assmann369bc182009-10-12 22:17:21 +0200882 ftrace_graph_filter=[function-list]
883 [FTRACE] Limit the top level callers functions traced
884 by the function graph tracer at boot up.
885 function-list is a comma separated list of functions
886 that can be changed at run time by the
887 set_graph_function file in the debugfs tracing directory.
888
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 gamecon.map[2|3]=
890 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
891 support via parallel port (up to 5 devices per port)
892 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
893 See also Documentation/input/joystick-parport.txt
894
895 gamma= [HW,DRM]
896
Yinghai Luaaf23042008-01-30 13:33:09 +0100897 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
898 Format: off | on
899 default: on
900
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700901 gcov_persist= [GCOV] When non-zero (default), profiling data for
902 kernel modules is saved and remains accessible via
903 debugfs, even when the module is unloaded/reloaded.
904 When zero, profiling data is discarded and associated
905 debugfs files are removed at module unload time.
906
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 gpt [EFI] Forces disk with valid GPT signature but
908 invalid Protective MBR to be treated as GPT.
909
Andreas Larsson6cec9b02012-11-15 08:47:14 +0100910 grcan.enable0= [HW] Configuration of physical interface 0. Determines
911 the "Enable 0" bit of the configuration register.
912 Format: 0 | 1
913 Default: 0
914 grcan.enable1= [HW] Configuration of physical interface 1. Determines
915 the "Enable 0" bit of the configuration register.
916 Format: 0 | 1
917 Default: 0
918 grcan.select= [HW] Select which physical interface to use.
919 Format: 0 | 1
920 Default: 0
921 grcan.txsize= [HW] Sets the size of the tx buffer.
922 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
923 Default: 1024
924 grcan.rxsize= [HW] Sets the size of the rx buffer.
925 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
926 Default: 1024
927
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 hashdist= [KNL,NUMA] Large hashes allocated during boot
929 are distributed across NUMA nodes. Defaults on
Randy Dunlap16290242011-08-13 12:34:52 -0700930 for 64-bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700931 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932
933 hcl= [IA-64] SGI's Hardware Graph compatibility layer
934
935 hd= [EIDE] (E)IDE hard drive subsystem geometry
936 Format: <cyl>,<head>,<sect>
937
Huang Yingea8c0712010-05-18 14:35:15 +0800938 hest_disable [ACPI]
939 Disable Hardware Error Source Table (HEST) support;
940 corresponding firmware-first mode error processing
941 logic will be disabled.
942
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
944 size of <nn>. This works even on boxes that have no
945 highmem otherwise. This also works to reduce highmem
946 size on bigger boxes.
947
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800948 highres= [KNL] Enable/disable high resolution timer mode.
949 Valid parameters: "on", "off"
950 Default: "on"
951
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 hisax= [HW,ISDN]
953 See Documentation/isdn/README.HiSax.
954
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700955 hlt [BUGS=ARM,SH]
956
957 hpet= [X86-32,HPET] option to control HPET usage
958 Format: { enable (default) | disable | force |
959 verbose }
960 disable: disable HPET and use PIT instead
961 force: allow force enabled of undocumented chips (ICH4,
962 VIA, nVidia)
963 verbose: show contents of HPET registers during setup
964
Andi Kleenb4718e62008-07-23 21:27:51 -0700965 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
966 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700967 On x86-64 and powerpc, this option can be specified
968 multiple times interleaved with hugepages= to reserve
969 huge pages of different sizes. Valid pages sizes on
970 x86-64 are 2M (when the CPU supports "pse") and 1G
971 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700972 Note that 1GB pages can only be allocated at boot time
973 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900974
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100975 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
976 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100977 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
978 If specified, z/VM IUCV HVC accepts connections
979 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100980
James Hoganfdabf522012-10-09 11:00:27 +0100981 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
982 hardware thread id mappings.
983 Format: <cpu>:<hwthread>
984
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -0700985 keep_bootcon [KNL]
986 Do not unregister boot console at start. This is only
987 useful for debugging when something happens in the window
988 between unregistering the boot console and initializing
989 the real console.
990
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700991 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700992 or register an additional I2C bus that is not
993 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700994 Format:
995 <bus_id>,<clkrate>
996
Jiri Kosina36d95732008-10-06 02:51:09 -0400997 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200999 i8042.dumbkbd [HW] Pretend that controller can only read data from
1000 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 (Don't attempt to blink the leds)
1002 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -05001003 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -04001004 i8042.noloop [HW] Disable the AUX Loopback command while probing
1005 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 i8042.nomux [HW] Don't check presence of an active multiplexing
1007 controller
1008 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1009 controllers
Masanari Iida24775d62012-02-15 00:26:42 +09001010 i8042.notimeout [HW] Ignore timeout condition signalled by controller
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 i8042.reset [HW] Reset the controller during init and cleanup
1012 i8042.unlock [HW] Unlock (ignore) the keylock
1013
1014 i810= [HW,DRM]
1015
Dmitry Torokhove70c9d52005-06-25 14:54:25 -07001016 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1017 indicates that the driver is running on unsupported
1018 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1020 does not match list of supported models.
1021 i8k.power_status
1022 [HW] Report power status in /proc/i8k
1023 (disabled by default)
1024 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1025 capability is set.
1026
Carsten Emde4dca20e2012-03-15 15:56:26 +01001027 i915.invert_brightness=
Carsten Emde7bd90902012-03-15 15:56:25 +01001028 [DRM] Invert the sense of the variable that is used to
1029 set the brightness of the panel backlight. Normally a
Carsten Emde4dca20e2012-03-15 15:56:26 +01001030 brightness value of 0 indicates backlight switched off,
1031 and the maximum of the brightness value sets the backlight
1032 to maximum brightness. If this parameter is set to 0
1033 (default) and the machine requires it, or this parameter
1034 is set to 1, a brightness value of 0 sets the backlight
1035 to maximum brightness, and the maximum of the brightness
1036 value switches the backlight off.
1037 -1 -- never invert brightness
1038 0 -- machine default
1039 1 -- force brightness inversion
Carsten Emde7bd90902012-03-15 15:56:25 +01001040
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 icn= [HW,ISDN]
1042 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1043
David Fries0af80c02009-02-25 20:28:21 +01001044 ide-core.nodma= [HW] (E)IDE subsystem
1045 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +02001046 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1047 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +01001048 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001050 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1051 Claim all unknown PCI IDE storage controllers.
1052
Andi Kleenf039b752007-05-02 19:27:12 +02001053 idle= [X86]
Len Brown69fb3672013-02-10 01:38:39 -05001054 Format: idle=poll, idle=halt, idle=nomwait
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001055 Poll forces a polling idle loop that can slightly
1056 improve the performance of waking up a idle CPU, but
1057 will use a lot of power and make the system run hot.
1058 Not recommended.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001059 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +08001060 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001061 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -07001062
Ingo Molnar792908222006-12-06 20:40:51 -08001063 ignore_loglevel [KNL]
1064 Ignore loglevel setting - this will print /all/
1065 kernel messages to the console. Useful for debugging.
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001066 We also add it as printk module parameter, so users
1067 could change it dynamically, usually by
1068 /sys/module/printk/parameters/ignore_loglevel.
Ingo Molnar792908222006-12-06 20:40:51 -08001069
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 ihash_entries= [KNL]
1071 Set number of hash buckets for inode cache.
1072
Mimi Zohar2fe5d6d2012-02-13 10:15:05 -05001073 ima_appraise= [IMA] appraise integrity measurements
1074 Format: { "off" | "enforce" | "fix" }
1075 default: "enforce"
1076
Mimi Zohar07f6a792011-03-09 22:25:48 -05001077 ima_appraise_tcb [IMA]
1078 The builtin appraise policy appraises all files
1079 owned by uid=0.
1080
Mimi Zohar3323eec92009-02-04 09:06:58 -05001081 ima_audit= [IMA]
1082 Format: { "0" | "1" }
1083 0 -- integrity auditing messages. (Default)
1084 1 -- enable informational integrity auditing messages.
1085
1086 ima_hash= [IMA]
Stephen Hemmingera9ed83a2009-09-17 14:14:45 -07001087 Format: { "sha1" | "md5" }
Mimi Zohar3323eec92009-02-04 09:06:58 -05001088 default: "sha1"
1089
Eric Paris5789ba32009-05-21 15:47:06 -04001090 ima_tcb [IMA]
1091 Load a policy which meets the needs of the Trusted
1092 Computing Base. This means IMA will measure all
1093 programs exec'd, files mmap'd for exec, and all files
1094 opened for read by uid=0.
1095
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 init= [KNL]
1097 Format: <full_path>
1098 Run specified binary instead of /sbin/init as init
1099 process.
1100
1101 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1102 for working out where the kernel is dying during
1103 startup.
1104
1105 initrd= [BOOT] Specify the location of the initial ramdisk
1106
1107 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1108 Format: <irq>
1109
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001110 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -08001111 on
1112 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -07001113 off
1114 Disable intel iommu driver.
1115 igfx_off [Default Off]
1116 By default, gfx is mapped as normal device. If a gfx
1117 device has a dedicated DMAR unit, the DMAR unit is
1118 bypassed by not enabling DMAR with this option. In
1119 this case, gfx device will use physical address for
1120 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001121 forcedac [x86_64]
1122 With this option iommu will not optimize to look
Randy Dunlap16290242011-08-13 12:34:52 -07001123 for io virtual address below 32-bit forcing dual
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001124 address cycle on pci bus for cards supporting greater
Randy Dunlap16290242011-08-13 12:34:52 -07001125 than 32-bit addressing. The default is to look
1126 for translation below 32-bit and if not available
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -07001127 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -08001128 strict [Default Off]
1129 With this option on every unmap_single operation will
1130 result in a hardware IOTLB flush operation as opposed
1131 to batching them for performance.
Youquan Song6dd9a7c2011-05-25 19:13:49 +01001132 sp_off [Default Off]
1133 By default, super page will be supported if Intel IOMMU
1134 has the capability. With this option, super page will
1135 not be supported.
Masanari Iida2e92c7a2011-12-15 01:18:52 +09001136
1137 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1138 0 disables intel_idle and fall back on acpi_idle.
1139 1 to 6 specify maximum depth of C-state.
1140
Dirk Brandewie6be26492013-02-15 22:55:10 +01001141 intel_pstate= [X86]
1142 disable
1143 Do not enable intel_pstate as the default
1144 scaling driver for the supported processors
1145
Chris Wrightd1423d52010-07-20 11:06:49 -07001146 intremap= [X86-64, Intel-IOMMU]
Chris Wrightd1423d52010-07-20 11:06:49 -07001147 on enable Interrupt Remapping (default)
1148 off disable Interrupt Remapping
1149 nosid disable Source ID checking
Suresh Siddha41750d32011-08-23 17:05:18 -07001150 no_x2apic_optout
1151 BIOS x2APIC opt-out request will be ignored
Chris Wrightd1423d52010-07-20 11:06:49 -07001152
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001153 iomem= Disable strict checking of access to MMIO memory
1154 strict regions from userspace.
1155 relaxed
1156
1157 iommu= [x86]
1158 off
1159 force
1160 noforce
1161 biomerge
1162 panic
1163 nopanic
1164 merge
1165 nomerge
1166 forcesac
1167 soft
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001168 pt [x86, IA-64]
Alex Williamsonbcb71ab2011-10-21 15:56:24 -04001169
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001170
1171 io7= [HW] IO7 for Marvel based alpha systems
1172 See comment before marvel_specify_io7 in
1173 arch/alpha/kernel/core_marvel.c.
1174
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301175 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001176 0x80
1177 Standard port 0x80 based delay
1178 0xed
1179 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001180 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001181 Simple two microseconds delay
1182 none
1183 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001184
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185 ip= [IP_PNP]
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001186 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187
1188 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001189 See comment before ip2_setup() in
1190 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
Alan Cox200803d2005-06-28 20:45:18 -07001192 irqfixup [HW]
1193 When an interrupt is not handled search all handlers
1194 for it. Intended to get systems with badly broken
1195 firmware running.
1196
1197 irqpoll [HW]
1198 When an interrupt is not handled search all handlers
1199 for it. Also check all handlers each timer
1200 interrupt. Intended to get systems with badly broken
1201 firmware running.
1202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001204 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205
1206 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001207 Format:
1208 <cpu number>,...,<cpu number>
1209 or
Li Zefanb225d442008-11-06 12:53:39 -08001210 <cpu number>-<cpu number>
1211 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001212 or a mixture
1213 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001214
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 This option can be used to specify one or more CPUs
1216 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001217 algorithms. You can move a process onto or off an
1218 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 <cpu number> begins at 0 and the maximum value is
1220 "number of CPUs in system - 1".
1221
1222 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001223 alternative -- manually setting the CPU mask of all
1224 tasks in the system -- can cause problems and
1225 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226
Randy Dunlapa9913042005-10-23 12:57:11 -07001227 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228
1229 js= [HW,JOY] Analog joystick
1230 See Documentation/input/joystick.txt.
1231
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001232 keepinitrd [HW,ARM]
1233
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301234 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001235 specifies the amount of memory usable by the kernel
1236 for non-movable allocations. The requested amount is
1237 spread evenly throughout all nodes in the system. The
1238 remaining memory in each node is used for Movable
1239 pages. In the event, a node is too small to have both
1240 kernelcore and Movable pages, kernelcore pages will
1241 take priority and other nodes will have a larger number
1242 of kernelcore pages. The Movable zone is used for the
1243 allocation of pages that may be reclaimed or moved
1244 by the page migration subsystem. This means that
1245 HugeTLB pages may not be allocated from this zone.
1246 Note that allocations like PTEs-from-HighMem still
1247 use the HighMem zone if it exists, and the Normal
1248 zone if it does not.
1249
Jason Wessel4fe1da42010-05-20 21:04:31 -05001250 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1251 Format: <Controller#>[,poll interval]
1252 The controller # is the number of the ehci usb debug
1253 port as it is probed via PCI. The poll interval is
1254 optional and is the number seconds in between
1255 each poll cycle to the debug port in case you need
1256 the functionality for interrupting the kernel with
1257 gdb or control-c on the dbgp connection. When
1258 not using this parameter you use sysrq-g to break into
1259 the kernel debugger.
1260
Jason Wessel84c08fd2010-05-20 21:04:24 -05001261 kgdboc= [KGDB,HW] kgdb over consoles.
Jason Wesselada64e42010-05-20 21:04:24 -05001262 Requires a tty driver that supports console polling,
1263 or a supported polling keyboard driver (non-usb).
Jason Wessel65b5ac12010-08-05 09:22:33 -05001264 Serial only format: <serial_device>[,baud]
1265 keyboard only format: kbd
1266 keyboard and serial format: kbd,<serial_device>[,baud]
1267 Optional Kernel mode setting:
1268 kms, kbd format: kms,kbd
1269 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001270
Jason Wessel84c08fd2010-05-20 21:04:24 -05001271 kgdbwait [KGDB] Stop kernel execution and enter the
1272 kernel debugger at the earliest opportunity.
1273
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001274 kmac= [MIPS] korina ethernet MAC address.
1275 Configure the RouterBoard 532 series on-chip
1276 Ethernet adapter MAC address.
1277
Catalin Marinas04f70332009-06-11 13:22:39 +01001278 kmemleak= [KNL] Boot-time kmemleak enable/disable
1279 Valid arguments: on, off
1280 Default: on
1281
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301282 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001283 in oops dumps.
1284
Andre Przywarafef07aa2009-07-10 14:20:35 +02001285 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1286 Default is 0 (don't ignore, but inject #GP)
1287
Xiao Guangronga182d872010-09-20 22:17:48 +08001288 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1289 KVM MMU at runtime.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001290 Default is 0 (off)
1291
Andre Przywarafef07aa2009-07-10 14:20:35 +02001292 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Xiao Guangrong8475f942010-09-20 22:16:45 +08001293 Default is 1 (enabled)
Andre Przywarafef07aa2009-07-10 14:20:35 +02001294
1295 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1296 for all guests.
Randy Dunlap16290242011-08-13 12:34:52 -07001297 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
Andre Przywarafef07aa2009-07-10 14:20:35 +02001298
Andre Przywarafef07aa2009-07-10 14:20:35 +02001299 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1300 (virtualized MMU) support on capable Intel chips.
1301 Default is 1 (enabled)
1302
1303 kvm-intel.emulate_invalid_guest_state=
1304 [KVM,Intel] Enable emulation of invalid guest states
1305 Default is 0 (disabled)
1306
1307 kvm-intel.flexpriority=
1308 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1309 Default is 1 (enabled)
1310
Sasha Levine1a72ae2011-08-09 14:28:35 +03001311 kvm-intel.nested=
1312 [KVM,Intel] Enable VMX nesting (nVMX).
1313 Default is 0 (disabled)
1314
Andre Przywarafef07aa2009-07-10 14:20:35 +02001315 kvm-intel.unrestricted_guest=
1316 [KVM,Intel] Disable unrestricted guest feature
1317 (virtualized real and unpaged mode) on capable
1318 Intel chips. Default is 1 (enabled)
1319
1320 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1321 feature (tagged TLBs) on capable Intel chips.
1322 Default is 1 (enabled)
1323
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 l2cr= [PPC]
1325
Robert Brosea78bfbf2008-03-29 07:20:23 +11001326 l3cr= [PPC]
1327
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001328 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001329 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Suresh Siddha279f1462012-10-22 14:37:58 -07001331 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1332 value for LAPIC timer one-shot implementation. Default
1333 back to the programmable timer unit in the LAPIC.
1334
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301335 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001336 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001337
FD Camifcb71f62008-01-06 19:08:56 +01001338 libata.dma= [LIBATA] DMA control
1339 libata.dma=0 Disable all PATA and SATA DMA
1340 libata.dma=1 PATA and SATA Disk DMA only
1341 libata.dma=2 ATAPI (CDROM) DMA only
Randy Dunlap16290242011-08-13 12:34:52 -07001342 libata.dma=4 Compact Flash DMA only
FD Camifcb71f62008-01-06 19:08:56 +01001343 Combinations also work, so libata.dma=3 enables DMA
1344 for disks and CDROMs, but not CFs.
Randy Dunlap16290242011-08-13 12:34:52 -07001345
Michael Prokop20308872009-08-06 00:14:10 +02001346 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1347 libata.ignore_hpa=0 keep BIOS limits (default)
1348 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001349
Dave Jones78e70c22007-09-27 11:50:13 -04001350 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1351 when set.
1352 Format: <int>
1353
Tejun Heo33267322008-02-13 09:15:09 +09001354 libata.force= [LIBATA] Force configurations. The format is comma
1355 separated list of "[ID:]VAL" where ID is
Roman Fietze4c44f302010-04-21 12:17:12 +02001356 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
Tejun Heo33267322008-02-13 09:15:09 +09001357 matching port, link or device. Basically, it matches
1358 the ATA ID string printed on console by libata. If
1359 the whole ID part is omitted, the last PORT and DEVICE
1360 values are used. If ID hasn't been specified yet, the
1361 configuration applies to all ports, links and devices.
1362
1363 If only DEVICE is omitted, the parameter applies to
1364 the port and all links and devices behind it. DEVICE
1365 number of 0 either selects the first device or the
1366 first fan-out link behind PMP device. It does not
1367 select the host link. DEVICE number of 15 selects the
1368 host link and device attached to it.
1369
1370 The VAL specifies the configuration to force. As long
1371 as there's no ambiguity shortcut notation is allowed.
1372 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1373 The following configurations can be forced.
1374
1375 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1376 Any ID with matching PORT is used.
1377
1378 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1379
1380 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1381 udma[/][16,25,33,44,66,100,133] notation is also
1382 allowed.
1383
1384 * [no]ncq: Turn on or off NCQ.
1385
Tejun Heo05944bd2008-08-13 20:19:09 +09001386 * nohrst, nosrst, norst: suppress hard, soft
1387 and both resets.
1388
Dan Williamsca6d43b2012-06-21 23:41:41 -07001389 * rstonce: only attempt one reset during
1390 hot-unplug link recovery
1391
Tejun Heo43c9c592010-05-23 12:59:11 +02001392 * dump_id: dump IDENTIFY data.
1393
Tejun Heo33267322008-02-13 09:15:09 +09001394 If there are multiple matching configurations changing
1395 the same attribute, the last one is used.
1396
Yinghai Lu95f72d12010-07-12 14:36:09 +10001397 memblock=debug [KNL] Enable memblock debug messages.
Randy Dunlap7c4be2532009-01-06 14:42:44 -08001398
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001400 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001402 lockd.nlm_grace_period=P [NFS] Assign grace period.
1403 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001405 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1406 Format: <integer>
1407
1408 lockd.nlm_timeout=T [NFS] Assign timeout value.
1409 Format: <integer>
1410
1411 lockd.nlm_udpport=M [NFS] Assign UDP port.
1412 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413
1414 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1415 Format: <irq>
1416
1417 loglevel= All Kernel Messages with a loglevel smaller than the
1418 console loglevel will be printed to the console. It can
1419 also be changed with klogd or other programs. The
1420 loglevels are defined as follows:
1421
1422 0 (KERN_EMERG) system is unusable
1423 1 (KERN_ALERT) action must be taken immediately
1424 2 (KERN_CRIT) critical conditions
1425 3 (KERN_ERR) error conditions
1426 4 (KERN_WARNING) warning conditions
1427 5 (KERN_NOTICE) normal but significant condition
1428 6 (KERN_INFO) informational
1429 7 (KERN_DEBUG) debug-level messages
1430
Randy Dunlapc756d082011-02-20 20:08:35 -08001431 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1432 in bytes. n must be a power of two. The default
1433 size is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434
Randy Dunlapaccaa242007-10-16 01:29:37 -07001435 logo.nologo [FB] Disables display of the built-in Linux logo.
1436 This may be used to provide more screen space for
1437 kernel log messages and is useful when debugging
1438 kernel boot problems.
1439
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 lp=0 [LP] Specify parallel ports to use, e.g,
1441 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1442 lp=reset first parallel port). 'lp=0' disables the
1443 lp=auto printer driver. 'lp=reset' (which can be
1444 specified in addition to the ports) causes
1445 attached printers to be reset. Using
1446 lp=port1,port2,... specifies the parallel ports
1447 to associate lp devices with, starting with
1448 lp0. A port specification may be 'none' to skip
1449 that lp device, or a parport name such as
1450 'parport0'. Specifying 'lp=auto' instead of a
1451 port specification list means that device IDs
1452 from each port should be examined, to see if
1453 an IEEE 1284-compliant printer is attached; if
1454 so, the driver will manage that printer.
1455 See also header of drivers/char/lp.c.
1456
1457 lpj=n [KNL]
1458 Sets loops_per_jiffy to given constant, thus avoiding
1459 time-consuming boot-time autodetection (up to 250 ms per
1460 CPU). 0 enables autodetection (default). To determine
1461 the correct value for your kernel, boot with normal
1462 autodetection and see what value is printed. Note that
1463 on SMP systems the preset will be applied to all CPUs,
1464 which is likely to cause problems if your CPUs need
1465 significantly divergent settings. An incorrect value
1466 will cause delays in the kernel to be wrong, leading to
1467 unpredictable I/O errors and other breakage. Although
1468 unlikely, in the extreme case this might damage your
1469 hardware.
1470
1471 ltpc= [NET]
1472 Format: <io>,<irq>,<dma>
1473
Randy Dunlap16290242011-08-13 12:34:52 -07001474 machvec= [IA-64] Force the use of a particular machine-vector
Randy Dunlapa9913042005-10-23 12:57:11 -07001475 (machvec) in a generic kernel.
1476 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477
Wu Zhangjin3209e702009-07-02 23:27:12 +08001478 machtype= [Loongson] Share the same kernel image file between different
1479 yeeloong laptop.
1480 Example: machtype=lemote-yeeloong-2f-7inch
1481
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001482 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1483 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484
1485 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001486 should make use of. maxcpus=n : n >= 0 limits the
1487 kernel to using 'n' processors. n=0 is a special case,
1488 it is equivalent to "nosmp", which also disables
1489 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490
Kay Sieversd134b002011-07-31 22:08:04 +02001491 max_loop= [LOOP] The number of loop block devices that get
1492 (loop.max_loop) unconditionally pre-created at init time. The default
1493 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1494 of statically allocating a predefined number, loop
1495 devices can be requested on-demand with the
1496 /dev/loop-control interface.
Bob Picco2b2c3752005-06-29 18:00:00 -07001497
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001498 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499
Uwe Hermann71cced62008-10-20 09:32:21 -07001500 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001501
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 md= [HW] RAID subsystems devices and level
1503 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 mdacon= [MDA]
1506 Format: <first>,<last>
1507 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001508
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1510 Amount of memory to be used when the kernel is not able
1511 to see the whole system memory or for test.
Wen Congyangfbb97d82012-12-17 15:59:29 -08001512 [X86] Work as limiting max address. Use together
1513 with memmap= to avoid physical address space collisions.
1514 Without memmap= PCI devices could be placed at addresses
1515 belonging to unused RAM.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001517 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 memory.
1519
Paul Mundt6902aa82008-09-21 17:14:42 +09001520 memchunk=nn[KMG]
1521 [KNL,SH] Allow user to override the default size for
1522 per-device physically contiguous DMA buffers.
1523
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301524 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 E820 memory map, as specified by the user.
1526 Such memmap=exactmap lines can be constructed based on
1527 BIOS output or other requirements. See the memmap=nn@ss
1528 option description.
1529
1530 memmap=nn[KMG]@ss[KMG]
1531 [KNL] Force usage of a specific region of memory
1532 Region of memory to be used, from ss to ss+nn.
1533
1534 memmap=nn[KMG]#ss[KMG]
1535 [KNL,ACPI] Mark specific memory as ACPI data.
1536 Region of memory to be used, from ss to ss+nn.
1537
1538 memmap=nn[KMG]$ss[KMG]
1539 [KNL,ACPI] Mark specific memory as reserved.
1540 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001541 Example: Exclude memory from 0x18690000-0x1869ffff
1542 memmap=64K$0x18690000
1543 or
1544 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001546 memory_corruption_check=0/1 [X86]
1547 Some BIOSes seem to corrupt the first 64k of
1548 memory when doing things like suspend/resume.
1549 Setting this option will scan the memory
1550 looking for corruption. Enabling this will
1551 both detect corruption and prevent the kernel
1552 from using the memory being corrupted.
1553 However, its intended as a diagnostic tool; if
1554 repeatable BIOS-originated corruption always
1555 affects the same memory, you can use memmap=
1556 to prevent the kernel from using that memory.
1557
1558 memory_corruption_check_size=size [X86]
1559 By default it checks for corruption in the low
1560 64k, making this memory unavailable for normal
1561 use. Use this parameter to scan for
1562 corruption in more or less memory.
1563
1564 memory_corruption_check_period=seconds [X86]
1565 By default it checks for corruption every 60
1566 seconds. Use this parameter to check at some
1567 other rate. 0 disables periodic checking.
1568
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001569 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001570 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001571 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001572 Specifies the number of memtest passes to be
1573 performed. Each pass selects another test
1574 pattern from a given set of patterns. Memtest
1575 fills the memory with this pattern, validates
1576 memory contents and reserves bad memory
1577 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001578
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579 meye.*= [HW] Set MotionEye Camera parameters
1580 See Documentation/video4linux/meye.txt.
1581
Andres Salomon8f368812007-10-12 23:04:06 +02001582 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1583 Multi-Function General Purpose Timers on AMD Geode
1584 platforms.
1585
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001586 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1587 the BIOS has incorrectly applied a workaround. TinyBIOS
1588 version 0.98 is known to be affected, 0.99 fixes the
1589 problem by letting the user disable the workaround.
1590
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 mga= [HW,DRM]
1592
Randy Dunlap1c207f92008-11-19 15:36:16 -08001593 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1594 physical address is ignored.
1595
Michel Pollet39f45d72009-05-20 11:10:31 +01001596 mini2440= [ARM,HW,KNL]
1597 Format:[0..2][b][c][t]
1598 Default: "0tb"
1599 MINI2440 configuration specification:
1600 0 - The attached screen is the 3.5" TFT
1601 1 - The attached screen is the 7" TFT
1602 2 - The VGA Shield is attached (1024x768)
1603 Leaving out the screen size parameter will not load
1604 the TFT driver, and the framebuffer will be left
1605 unconfigured.
1606 b - Enable backlight. The TFT backlight pin will be
1607 linked to the kernel VESA blanking code and a GPIO
1608 LED. This parameter is not necessary when using the
1609 VGA shield.
1610 c - Enable the s3c camera interface.
1611 t - Reserved for enabling touchscreen support. The
1612 touchscreen support is not enabled in the mainstream
1613 kernel as of 2.6.30, a preliminary port can be found
1614 in the "bleeding edge" mini2440 support kernel at
1615 http://repo.or.cz/w/linux-2.6/mini2440.git
1616
Mel Gorman6b74ab92008-07-23 21:26:49 -07001617 mminit_loglevel=
1618 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1619 parameter allows control of the logging verbosity for
1620 the additional memory initialisation checks. A value
1621 of 0 disables mminit logging and a level of 4 will
1622 log everything. Information is printed at KERN_DEBUG
1623 so loglevel=8 may also need to be specified.
1624
Rusty Russell106a4ee2012-09-26 10:09:40 +01001625 module.sig_enforce
1626 [KNL] When CONFIG_MODULE_SIG is set, this means that
1627 modules without (valid) signatures will fail to load.
1628 Note that if CONFIG_MODULE_SIG_ENFORCE is set, that
1629 is always true, so this option does nothing.
1630
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 mousedev.tap_time=
1632 [MOUSE] Maximum time between finger touching and
1633 leaving touchpad surface for touch to be considered
1634 a tap and be reported as a left button click (for
1635 touchpads working in absolute mode only).
1636 Format: <msecs>
1637 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1638 reporting absolute coordinates, such as tablets
1639 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1640 reporting absolute coordinates, such as tablets
1641
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301642 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001643 is similar to kernelcore except it specifies the
1644 amount of memory used for migratable allocations.
1645 If both kernelcore and movablecore is specified,
1646 then kernelcore will be at *least* the specified
1647 value but may be more. If movablecore on its own
1648 is specified, the administrator must be careful
1649 that the amount of memory usable for all allocations
1650 is not too small.
1651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 MTD_Partition= [MTD]
1653 Format: <name>,<region-number>,<size>,<offset>
1654
Randy Dunlapa9913042005-10-23 12:57:11 -07001655 MTD_Region= [MTD] Format:
1656 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657
1658 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001659 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660
Will Schmidt4e89a2d2010-09-28 15:33:12 +00001661 multitce=off [PPC] This parameter disables the use of the pSeries
1662 firmware feature for updating multiple TCE entries
1663 at a time.
1664
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001665 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1666
1667 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1668
1669 boundary - index of last SLC block on Flex-OneNAND.
1670 The remaining blocks are configured as MLC blocks.
1671 lock - Configure if Flex-OneNAND boundary should be locked.
1672 Once locked, the boundary cannot be changed.
1673 1 indicates lock status, 0 indicates unlock status.
1674
Ben Dooks9db829f2008-07-03 11:24:29 +01001675 mtdset= [ARM]
1676 ARM/S3C2412 JIVE boot control
1677
1678 See arch/arm/mach-s3c2412/mach-jive.c
1679
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001681 [HW] Make the MicroTouch USB driver use raw coordinates
1682 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001684 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001685 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001686 that could hold holes aka. UC entries.
1687
1688 mtrr_gran_size=nn[KMG] [X86]
1689 Used for mtrr cleanup. It is granularity of mtrr block.
1690 Default is 1.
1691 Large value could prevent small alignment from
1692 using up MTRRs.
1693
1694 mtrr_spare_reg_nr=n [X86]
1695 Format: <integer>
1696 Range: 0,7 : spare reg number
1697 Default : 1
1698 Used for mtrr cleanup. It is spare mtrr entries number.
1699 Set to 2 or more if your graphical card needs more.
1700
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1702
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 netdev= [NET] Network devices parameters
1704 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1705 Note that mem_start is often overloaded to mean
1706 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001707 This usage is only documented in each driver source
1708 file if at all.
1709
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001710 nf_conntrack.acct=
1711 [NETFILTER] Enable connection tracking flow accounting
1712 0 to disable accounting
1713 1 to enable accounting
Tim Gardnerd70a0112010-06-25 14:46:56 +02001714 Default value is 0.
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001715
Chuck Lever306a0752010-09-17 10:54:37 -04001716 nfsaddrs= [NFS] Deprecated. Use ip= instead.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001717 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718
1719 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fieldsdc7a0812009-10-27 14:41:35 -04001720 See Documentation/filesystems/nfs/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
Chuck Lever306a0752010-09-17 10:54:37 -04001722 nfsrootdebug [NFS] enable nfsroot debugging messages.
1723 See Documentation/filesystems/nfs/nfsroot.txt.
1724
Trond Myklebusta72b4422006-01-03 09:55:41 +01001725 nfs.callback_tcpport=
1726 [NFS] set the TCP port on which the NFSv4 callback
1727 channel should listen.
1728
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001729 nfs.cache_getent=
1730 [NFS] sets the pathname to the program which is used
1731 to update the NFS client cache entries.
1732
1733 nfs.cache_getent_timeout=
1734 [NFS] sets the timeout after which an attempt to
1735 update a cache entry is deemed to have failed.
1736
Trond Myklebust58df0952006-01-03 09:55:57 +01001737 nfs.idmap_cache_timeout=
1738 [NFS] set the maximum lifetime for idmapper cache
1739 entries.
1740
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001741 nfs.enable_ino64=
1742 [NFS] enable 64-bit inode numbers.
1743 If zero, the NFS client will fake up a 32-bit inode
1744 number for the readdir() and stat() syscalls instead
1745 of returning the full 64-bit number.
1746 The default is to return 64-bit inode numbers.
1747
Trond Myklebustef159e92012-02-06 19:50:40 -05001748 nfs.max_session_slots=
1749 [NFSv4.1] Sets the maximum number of session slots
1750 the client will attempt to negotiate with the server.
1751 This limits the number of simultaneous RPC requests
1752 that the client can send to the NFSv4.1 server.
1753 Note that there is little point in setting this
1754 value higher than the max_tcp_slot_table_limit.
1755
Trond Myklebustb064eca22011-02-22 15:44:32 -08001756 nfs.nfs4_disable_idmapping=
Trond Myklebust074b1d12012-01-09 13:46:26 -05001757 [NFSv4] When set to the default of '1', this option
1758 ensures that both the RPC level authentication
1759 scheme and the NFS level operations agree to use
1760 numeric uids/gids if the mount is using the
1761 'sec=sys' security flavour. In effect it is
1762 disabling idmapping, which can make migration from
1763 legacy NFSv2/v3 systems to NFSv4 easier.
1764 Servers that do not support this mode of operation
1765 will be autodetected by the client, and it will fall
1766 back to using the idmapper.
1767 To turn off this behaviour, set the value to '0'.
Chuck Lever6f2ea7f2012-09-14 17:24:41 -04001768 nfs.nfs4_unique_id=
1769 [NFS4] Specify an additional fixed unique ident-
1770 ification string that NFSv4 clients can insert into
1771 their nfs_client_id4 string. This is typically a
1772 UUID that is generated at system install time.
Trond Myklebustb064eca22011-02-22 15:44:32 -08001773
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05001774 nfs.send_implementation_id =
1775 [NFSv4.1] Send client implementation identification
1776 information in exchange_id requests.
1777 If zero, no implementation identification information
1778 will be sent.
1779 The default is to send the implementation identification
1780 information.
1781
J. Bruce Fieldse9541ce2012-03-22 16:07:18 -04001782 nfsd.nfs4_disable_idmapping=
1783 [NFSv4] When set to the default of '1', the NFSv4
1784 server will return only numeric uids and gids to
1785 clients using auth_sys, and will accept numeric uids
1786 and gids from such clients. This is intended to ease
1787 migration from NFSv2/v3.
Weston Andros Adamsondb8ac8b2012-02-17 15:20:24 -05001788
Sachin Bhamare18d98f62012-03-19 20:47:58 -07001789 objlayoutdriver.osd_login_prog=
1790 [NFS] [OBJLAYOUT] sets the pathname to the program which
1791 is used to automatically discover and login into new
1792 osd-targets. Please see:
1793 Documentation/filesystems/pnfs.txt for more explanations
1794
Paul Mundt1e1030d2009-09-01 17:38:32 +09001795 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001796 when a NMI is triggered.
1797 Format: [state][,regs][,debounce][,die]
1798
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301799 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Don Zickusfef2c9b2011-03-22 16:34:16 -07001800 Format: [panic,][nopanic,][num]
Don Zickus5dc30552010-11-29 17:07:17 -05001801 Valid num: 0
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001802 0 - turn nmi_watchdog off
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001803 When panic is specified, panic when an NMI watchdog
Don Zickusfef2c9b2011-03-22 16:34:16 -07001804 timeout occurs (or 'nopanic' to override the opposite
1805 default).
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001806 This is useful when you use a panic=... timeout and
1807 need the box quickly up again.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808
Anton Vorontsovbff38772009-07-08 11:10:56 -07001809 netpoll.carrier_timeout=
1810 [NET] Specifies amount of time (in seconds) that
1811 netpoll should wait for a carrier. By default netpoll
1812 waits 4 seconds.
1813
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001814 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 emulation library even if a 387 maths coprocessor
1816 is present.
1817
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001818 no_console_suspend
1819 [HW] Never suspend the console
1820 Disable suspending of consoles during suspend and
1821 hibernate operations. Once disabled, debugging
1822 messages can reach various consoles while the rest
1823 of the system is being put to sleep (ie, while
1824 debugging driver suspend/resume hooks). This may
1825 not work reliably with all consoles, but is known
1826 to work with serial and VGA consoles.
Yanmin Zhang134620f2011-10-31 17:11:27 -07001827 To facilitate more flexible debugging, we also add
1828 console_suspend, a printk module parameter to control
1829 it. Users could use console_suspend (usually
1830 /sys/module/printk/parameters/console_suspend) to
1831 turn on/off it dynamically.
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001832
Christoph Lameterc1aee212007-05-31 00:40:47 -07001833 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1834 caches in the slab allocator. Saves per-node memory,
1835 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001836
Randy Dunlapa9913042005-10-23 12:57:11 -07001837 noalign [KNL,ARM]
1838
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 noapic [SMP,APIC] Tells the kernel to not make use of any
1840 IOAPICs that may be present in the system.
1841
Mike Galbraith5091faa2010-11-30 14:18:03 +01001842 noautogroup Disable scheduler automatic task group creation.
1843
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 nobats [PPC] Do not use BATs for mapping kernel lowmem
1845 on "Classic" PPC cores.
1846
1847 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001848
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001849 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1850
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001851 nodelayacct [KNL] Disable per-task delay accounting
1852
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1854
Paul Mundt6902aa82008-09-21 17:14:42 +09001855 nodsp [SH] Disable hardware DSP at boot time.
1856
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301857 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001858
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 noexec [IA-64]
1860
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301861 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001862 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001864 noexec=off: disable non-executable mappings
1865
H. Peter Anvin52b61792012-09-21 12:43:13 -07001866 nosmap [X86]
1867 Disable SMAP (Supervisor Mode Access Prevention)
1868 even if it is supported by processor.
1869
Fenghua Yude5397a2011-05-11 16:51:05 -07001870 nosmep [X86]
H. Peter Anvin52b61792012-09-21 12:43:13 -07001871 Disable SMEP (Supervisor Mode Execution Prevention)
Fenghua Yude5397a2011-05-11 16:51:05 -07001872 even if it is supported by processor.
1873
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001874 noexec32 [X86-64]
1875 This affects only 32-bit executables.
1876 noexec32=on: enable non-executable mappings (default)
1877 read doesn't imply executable mappings
1878 noexec32=off: disable non-executable mappings
1879 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880
Paul Mundt6902aa82008-09-21 17:14:42 +09001881 nofpu [SH] Disable hardware FPU at boot time.
1882
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001883 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001884 register save and restore. The kernel will only save
1885 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886
Suresh Siddha0c752a92009-05-22 12:17:45 -07001887 noxsave [BUGS=X86] Disables x86 extended register state save
1888 and restore using xsave. The kernel will fallback to
1889 enabling legacy floating-point and sse state.
1890
Suresh Siddha5d2bd702012-09-06 14:58:52 -07001891 eagerfpu= [X86]
Suresh Siddhae0022982012-09-10 10:32:32 -07001892 on enable eager fpu restore
Suresh Siddha5d2bd702012-09-06 14:58:52 -07001893 off disable eager fpu restore
Suresh Siddhae0022982012-09-10 10:32:32 -07001894 auto selects the default scheme, which automatically
1895 enables eagerfpu restore for xsaveopt.
Suresh Siddha5d2bd702012-09-06 14:58:52 -07001896
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001897 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1898 wfi(ARM) instruction doesn't work correctly and not to
1899 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001900
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001901 no_file_caps Tells the kernel not to honor file capabilities. The
1902 only way then for a file to be executed with privilege
1903 is to be setuid root or executed by root.
1904
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 nohalt [IA-64] Tells the kernel not to use the power saving
1906 function PAL_HALT_LIGHT when idle. This increases
1907 power-consumption. On the positive side, it reduces
1908 interrupt wake-up latency, which may improve performance
1909 in certain environments such as networked servers or
1910 real-time systems.
1911
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001912 nohz= [KNL] Boottime enable/disable dynamic ticks
1913 Valid arguments: on, off
1914 Default: on
1915
Paul Mundteeee7852009-04-02 12:31:16 +09001916 noiotrap [SH] Disables trapped I/O port accesses.
1917
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001918 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 disable unhandled interrupt sources.
1920
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301921 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001922 broken timer IRQ sources.
1923
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 noisapnp [ISAPNP] Disables ISA PnP code.
1925
1926 noinitrd [RAM] Tells the kernel not to load any configured
1927 initial RAM disk.
1928
Weidong Han03ea8152009-04-17 16:42:15 +08001929 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1930 remapping.
Chris Wrightd1423d52010-07-20 11:06:49 -07001931 [Deprecated - use intremap=off]
Weidong Han03ea8152009-04-17 16:42:15 +08001932
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 nointroute [IA-64]
1934
Randy Dunlap16290242011-08-13 12:34:52 -07001935 nojitter [IA-64] Disables jitter checking for ITC timers.
Tony Luck0aa366f2007-07-20 11:22:30 -07001936
Jiri Kosina9cf4c4f2010-08-16 17:51:20 +02001937 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1938
Gleb Natapovfd10cde2010-10-14 11:22:51 +02001939 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1940 fault handling.
1941
Glauber Costad910f5c2011-07-11 15:28:19 -04001942 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1943 steal time is computed, but won't influence scheduler
1944 behaviour
1945
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001946 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001948 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001949
Linus Torvalds1da177e2005-04-16 15:20:36 -07001950 noltlbs [PPC] Do not use large page/tlb entries for kernel
1951 lowmem mapping on PPC40x.
1952
Horms312f1f02006-02-22 09:57:55 +09001953 nomca [IA-64] Disable machine check abort handling
1954
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001955 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001956
Andres Salomon83d73842007-10-12 23:04:06 +02001957 nomfgpt [X86-32] Disable Multi-Function General Purpose
1958 Timer usage (for AMD Geode machines).
1959
Don Zickusbda62632011-10-13 15:14:27 -04001960 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
1961 shutdown the other cpus. Instead use the REBOOT_VECTOR
1962 irq.
1963
Dave Young02608be2012-02-01 10:33:14 +08001964 nomodule Disable module load
1965
Jiri Kosina016ddd92010-01-18 17:05:40 +01001966 nopat [X86] Disable PAT (page attribute table extension of
1967 pagetables) support.
1968
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001969 norandmaps Don't use address space randomization. Equivalent to
1970 echo 0 > /proc/sys/kernel/randomize_va_space
1971
Jiri Kosinabbff2162010-08-11 18:34:09 +02001972 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001973
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001974 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001975 with UP alternatives
1976
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977 noresidual [PPC] Don't use residual data on PReP machines.
1978
H. Peter Anvin49d859d2011-07-31 14:02:19 -07001979 nordrand [X86] Disable the direct use of the RDRAND
1980 instruction even if it is supported by the
1981 processor. RDRAND is still available to user
1982 space applications.
1983
Randy Dunlapa9913042005-10-23 12:57:11 -07001984 noresume [SWSUSP] Disables resume and restores original swap
1985 space.
1986
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 no-scroll [VGA] Disables scrollback.
1988 This is required for the Braillex ib80-piezo Braille
1989 reader made by F.H. Papenmeier (Germany).
1990
1991 nosbagart [IA-64]
1992
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001993 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001994
Len Brown61ec7562007-08-16 03:34:22 -04001995 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1996 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997
Dave Jones97842212007-07-15 23:41:05 -07001998 nosoftlockup [KNL] Disable the soft-lockup detector.
1999
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000 nosync [HW,M68K] Disables sync negotiation for all devices.
2001
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002002 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07002003
2004 nousb [USB] Disable the USB subsystem
2005
Ben Hutchings55142372011-01-02 23:02:42 +00002006 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
Don Zickus58687ac2010-05-07 17:11:44 -04002007
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07002009
Weidong Han2b2fd872009-04-17 16:42:12 +08002010 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2011
Fenghua Yuf78cff42012-11-13 11:32:38 -08002012 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2013 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2014 Some features depend on CPU0. Known dependencies are:
2015 1. Resume from suspend/hibernate depends on CPU0.
2016 Suspend/hibernate will fail if CPU0 is offline and you
2017 need to online CPU0 before suspend/hibernate.
2018 2. PIC interrupts also depend on CPU0. CPU0 can't be
2019 removed if a PIC interrupt is detected.
2020 It's said poweroff/reboot may depend on CPU0 on some
2021 machines although I haven't seen such issues so far
2022 after CPU0 is offline on a few tested machines.
2023 If the dependencies are under your control, you can
2024 turn on cpu0_hotplug.
2025
Randy Dunlap16290242011-08-13 12:34:52 -07002026 nptcg= [IA-64] Override max number of concurrent global TLB
Fenghua Yua6c75b862008-03-14 13:57:08 -07002027 purges which is reported from either PAL_VM_SUMMARY or
2028 SAL PALO.
2029
Yinghai Lu2b633e32010-02-10 01:20:37 -08002030 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2031 could support. nr_cpus=n : n >= 1 limits the kernel to
2032 supporting 'n' processors. Later in runtime you can not
2033 use hotplug cpu feature to put more cpu back to online.
2034 just like you compile the kernel NR_CPUS=n
2035
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002036 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2037
Mel Gorman1a687c22012-11-22 11:16:36 +00002038 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2039 Allowed values are enable and disable
2040
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07002041 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2042 one of ['zone', 'node', 'default'] can be specified
2043 This can be set from sysctl after boot.
2044 See Documentation/sysctl/vm.txt for details.
2045
Randy Dunlap7c4be2532009-01-06 14:42:44 -08002046 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2047 See Documentation/debugging-via-ohci1394.txt for more
2048 info.
2049
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07002050 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2051 Rather than timing out after 20 ms if an EC
2052 command is not properly ACKed, override the length
2053 of the timeout. We have interrupts disabled while
2054 waiting for the ACK, so if this is set too high
2055 interrupts *may* be lost!
2056
Tony Lindgren15ac7af2009-12-11 16:16:32 -08002057 omap_mux= [OMAP] Override bootloader pin multiplexing.
2058 Format: <mux_mode0.mode_name=value>...
2059 For example, to override I2C bus2:
2060 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2061
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062 oprofile.timer= [HW]
2063 Use timer interrupt instead of performance counters
2064
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002065 oprofile.cpu_type= Force an oprofile cpu type
2066 This might be useful if you have an older oprofile
2067 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02002068 Format: { arch_perfmon }
2069 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02002070 perfmon on Intel CPUs instead of the
2071 CPU specific event set.
Robert Richter159a80b2011-10-11 19:39:16 +02002072 timer: [X86] Force use of architectural NMI
2073 timer mode (see also oprofile.timer
2074 for generic hr timer mode)
Andreas Krebbeldd3c4672011-11-25 20:03:05 +01002075 [s390] Force legacy basic mode sampling
2076 (report cpu_type "timer")
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02002077
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002078 oops=panic Always panic on oopses. Default is to just kill the
2079 process, but there is a small probability of
2080 deadlocking the machine.
Olaf Heringd404ab02011-03-22 16:34:04 -07002081 This will also cause panics on machine check exceptions.
2082 Useful together with panic=30 to trigger a reboot.
2083
Randy Dunlapbcfde332010-06-07 17:10:38 -07002084 OSS [HW,OSS]
2085 See Documentation/sound/oss/oss-parameters.txt
2086
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002087 panic= [KNL] Kernel behaviour on panic: delay <timeout>
Hugh Dickins4302fbc2011-07-26 16:08:52 -07002088 timeout > 0: seconds before rebooting
2089 timeout = 0: wait forever
2090 timeout < 0: reboot immediately
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 Format: <timeout>
2092
2093 parkbd.port= [HW] Parallel port number the keyboard adapter is
2094 connected to, default is 0.
2095 Format: <parport#>
2096 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2097 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07002098 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099
Randy Dunlapa9913042005-10-23 12:57:11 -07002100 parport= [HW,PPT] Specify parallel ports. 0 disables.
2101 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2102 Use 'auto' to force the driver to use any
2103 IRQ/DMA settings detected (the default is to
2104 ignore detected IRQ/DMA settings because of
2105 possible conflicts). You can specify the base
2106 address, IRQ, and DMA settings; IRQ and DMA
2107 should be numbers, or 'auto' (for using detected
2108 settings on that particular port), or 'nofifo'
2109 (to avoid using a FIFO even if it is detected).
2110 Parallel ports are assigned in the order they
2111 are specified on the command line, starting
2112 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
Randy Dunlapa9913042005-10-23 12:57:11 -07002114 parport_init_mode= [HW,PPT]
2115 Configure VIA parallel port to operate in
2116 a specific mode. This is necessary on Pegasos
2117 computer where firmware has no options for setting
2118 up parallel port mode and sets it to spp.
2119 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120 Format: [spp|ps2|epp|ecp|ecpepp]
2121
Andrew Mortondd287792006-03-23 03:00:57 -08002122 pause_on_oops=
2123 Halt all CPUs after the first oops has been printed for
2124 the specified number of seconds. This is to be used if
2125 your oopses keep scrolling off the screen.
2126
Linus Torvalds1da177e2005-04-16 15:20:36 -07002127 pcbit= [HW,ISDN]
2128
2129 pcd. [PARIDE]
2130 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002131 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132
Randy Dunlapa9913042005-10-23 12:57:11 -07002133 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07002134 earlydump [X86] dump PCI config space before the kernel
2135 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02002136 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002137 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07002138 the hardware directly. Use this if your machine
2139 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002140 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07002141 hardware access methods are allowed. Use this
2142 if you experience crashes upon bootup and you
2143 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002144 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002145 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02002146 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07002147 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07002148 noaer [PCIE] If the PCIEAER kernel config parameter is
2149 enabled, this kernel boot option can be used to
2150 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04002151 nodomains [PCI] Disable support for multiple PCI
2152 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302153 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08002154 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02002155 check_enable_amd_mmconf [X86] check for and enable
2156 properly configured MMIO access to PCI
2157 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07002158 nomsi [MSI] If the PCI_MSI kernel config parameter is
2159 enabled, this kernel boot option can be used to
2160 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02002161 noioapicquirk [APIC] Disable all boot interrupt quirks.
2162 Safety option to keep boot IRQs enabled. This
2163 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02002164 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2165 primary IO-APIC for bridges that cannot disable
2166 boot IRQs. This fixes a source of spurious IRQs
2167 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02002168 noioapicreroute [APIC] Disable workaround that uses the
2169 boot IRQ equivalent of an IRQ that connects to
2170 a chipset where boot IRQs cannot be disabled.
2171 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002172 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07002173 routing table. These calls are known to be buggy
2174 on several machines and they hang the machine
2175 when used, but on other computers it's the only
2176 way to get the interrupt routing table. Try
2177 this option if the kernel is unable to allocate
2178 IRQs or discover secondary PCI buses on your
2179 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02002180 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07002181 Use with caution as certain devices share
2182 address decoders between ROMs and other
2183 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02002184 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07002185 expansion ROMs that do not already have
2186 BIOS assigned address ranges.
Mike Habeck7bd1c362010-05-12 11:14:32 -07002187 nobar [X86] Do not assign address space to the
2188 BARs that weren't assigned by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02002189 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07002190 assigned automatically to PCI devices. You can
2191 make the kernel exclude IRQs of your ISA cards
2192 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02002193 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07002194 of the PIRQ table (normally generated
2195 by the BIOS) if it is outside the
2196 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02002197 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07002198 useful if the kernel is unable to find your
2199 secondary buses and you want to tell it
2200 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02002201 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07002202 numbers ourselves, overriding
2203 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02002204 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07002205 in the BIOS $PIR table. This is needed on
2206 some systems with broken BIOSes, notably
2207 some HP Pavilion N5400 and Omnibook XE3
2208 notebooks. This will have no effect if ACPI
2209 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02002210 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07002211 or for PCI scanning.
Bjorn Helgaas7bc5e3f2010-02-23 10:24:41 -07002212 use_crs [X86] Use PCI host bridge window information
2213 from ACPI. On BIOSes from 2008 or later, this
2214 is enabled by default. If you need to use this,
2215 please report a bug.
2216 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2217 If you need to use this, please report a bug.
Randy Dunlapa9913042005-10-23 12:57:11 -07002218 routeirq Do IRQ routing for all PCI devices.
2219 This is normally done in pci_enable_device(),
2220 so this option is a temporary workaround
2221 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07002222 skip_isa_align [X86] do not align io start addr, so can
2223 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07002224 firmware [ARM] Do not re-enumerate the bus but instead
2225 just use the configuration from the
2226 bootloader. This is currently used on
2227 IXP2000 systems where the bus has to be
2228 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02002229 noearly [X86] Don't do any early type 1 scanning.
2230 This might help on some broken boards which
2231 machine check when some devices' config space
2232 is read. But various workarounds are disabled
2233 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002234 bfsort Sort PCI devices into breadth-first order.
2235 This sorting is done to get a device
2236 order compatible with older (<= 2.4) kernels.
2237 nobfsort Don't sort PCI devices into breadth-first order.
Yijing Wangfa238712013-01-30 09:40:52 +08002238 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2239 tuning and use the BIOS-configured MPS defaults.
2240 pcie_bus_safe Set every device's MPS to the largest value
2241 supported by all devices below the root complex.
2242 pcie_bus_perf Set device MPS to the largest allowable MPS
2243 based on its parent bus. Also set MRRS (Max
2244 Read Request Size) to the largest supported
2245 value (no larger than the MPS that the device
2246 or bus can support) for best performance.
2247 pcie_bus_peer2peer Set every device's MPS to 128B, which
2248 every device is guaranteed to support. This
2249 configuration allows peer-to-peer DMA between
2250 any pair of devices, possibly at the cost of
2251 reduced performance. This also guarantees
2252 that hot-added devices will work.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08002253 cbiosize=nn[KMG] The fixed amount of bus space which is
2254 reserved for the CardBus bridge's IO window.
2255 The default value is 256 bytes.
2256 cbmemsize=nn[KMG] The fixed amount of bus space which is
2257 reserved for the CardBus bridge's memory
2258 window. The default value is 64 megabytes.
Yuji Shimada32a9a6822009-03-16 17:13:39 +09002259 resource_alignment=
2260 Format:
2261 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2262 Specifies alignment and device to reassign
2263 aligned memory resources.
2264 If <order of align> is not specified,
2265 PAGE_SIZE is used as alignment.
2266 PCI-PCI bridge can be specified, if resource
2267 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06002268 ecrc= Enable/disable PCIe ECRC (transaction layer
2269 end-to-end CRC checking).
2270 bios: Use BIOS/firmware settings. This is the
2271 the default.
2272 off: Turn ECRC off
2273 on: Turn ECRC on.
Yijing Wang8c8803c2013-01-23 20:29:06 +08002274 hpiosize=nn[KMG] The fixed amount of bus space which is
2275 reserved for hotplug bridge's IO window.
2276 Default size is 256 bytes.
2277 hpmemsize=nn[KMG] The fixed amount of bus space which is
2278 reserved for hotplug bridge's memory window.
2279 Default size is 2 megabytes.
Yinghai Lub55438f2012-02-23 19:23:30 -08002280 realloc= Enable/disable reallocating PCI bridge resources
2281 if allocations done by BIOS are too small to
2282 accommodate resources required by all child
2283 devices.
2284 off: Turn realloc off
2285 on: Turn realloc on
2286 realloc same as realloc=on
Rafael J. Wysocki6748dcc2012-03-01 00:06:33 +01002287 noari do not use PCIe ARI.
Bjorn Helgaas284f5f92012-04-30 15:21:02 -06002288 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2289 only look for one device below a PCIe downstream
2290 port.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05002291
Chuck Ebberte5665a42008-09-24 20:40:34 -04002292 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2293 Management.
2294 off Disable ASPM.
2295 force Enable ASPM even on devices that claim not to support it.
2296 WARNING: Forcing ASPM on may cause system lockups.
2297
MUNEDA Takahiro7570a332012-02-02 11:09:22 -05002298 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2299 nomsi Do not use MSI for PCI Express Native Hotplug (this
2300 makes all PCIe ports use INTx for hotplug services).
2301
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002302 pcie_ports= [PCIE] PCIe ports handling:
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002303 auto Ask the BIOS whether or not to use native PCIe services
2304 associated with PCIe ports (PME, hot-plug, AER). Use
2305 them only if that is allowed by the BIOS.
2306 native Use native PCIe services associated with PCIe ports
2307 unconditionally.
Rafael J. Wysocki79dd9182010-08-21 01:51:44 +02002308 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2309 ports driver.
2310
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002311 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
Rafael J. Wysockic39fae12010-02-17 23:40:07 +01002312 nomsi Do not use MSI for native PCIe PME signaling (this makes
Rafael J. Wysocki28eb5f22010-08-21 22:02:38 +02002313 all PCIe root ports use INTx for all services).
Rafael J. Wysockic7f48652010-02-17 23:39:08 +01002314
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315 pcmv= [HW,PCMCIA] BadgePAD 4
2316
2317 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002318 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319
2320 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2321 boot time.
2322 Format: { 0 | 1 }
2323 See arch/parisc/kernel/pdc_chassis.c
2324
Tejun Heof58dc012009-08-14 15:00:50 +09002325 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09002326 Currently supported values are "embed" and "page".
2327 Archs may support subset or none of the selections.
2328 See comments in mm/percpu.c for details on each
2329 allocator. This parameter is primarily for debugging
2330 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09002331
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002333 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334
2335 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002336 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337
2338 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07002339 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340
2341 plip= [PPT,NET] Parallel port network link
2342 Format: { parport<nr> | timid | 0 }
2343 See also Documentation/parport.txt.
2344
Randy Dunlap16290242011-08-13 12:34:52 -07002345 pmtmr= [X86] Manual setup of pmtmr I/O Port.
Thomas Gleixnerde32a242008-07-12 05:33:30 +02002346 Override pmtimer IOPort with a hex value.
2347 e.g. pmtmr=0x508
2348
Bjorn Helgaas96242112011-08-11 12:14:05 -06002349 pnp.debug=1 [PNP]
2350 Enable PNP debug messages (depends on the
2351 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2352 via /sys/module/pnp/parameters/debug. We always show
2353 current resource usage; turning this on also shows
2354 possible settings and some assignment information.
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002355
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356 pnpacpi= [ACPI]
2357 { off }
2358
2359 pnpbios= [ISAPNP]
2360 { on | off | curr | res | no-curr | no-res }
2361
2362 pnp_reserve_irq=
2363 [ISAPNP] Exclude IRQs for the autoconfiguration
2364
2365 pnp_reserve_dma=
2366 [ISAPNP] Exclude DMAs for the autoconfiguration
2367
2368 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002369 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370
2371 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002372 [ISAPNP] Exclude memory regions for the
2373 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374 Ranges are in pairs (memory base and size).
2375
Randy Dunlap4af94f32009-04-17 18:30:28 -07002376 ports= [IP_VS_FTP] IPVS ftp helper module
2377 Default is 21.
2378 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2379 may be specified.
2380 Format: <port>,<port>....
2381
Ingo Molnar45807a12007-07-15 23:40:10 -07002382 print-fatal-signals=
2383 [KNL] debug: print fatal signals
Naohiro Ooiwaf84d49b2009-11-09 00:46:42 +09002384
2385 If enabled, warn about various signal handling
2386 related application anomalies: too many signals,
2387 too many POSIX.1 timers, fatal signals causing a
2388 coredump - etc.
2389
2390 If you hit the warning due to signal overflow,
2391 you might want to try "ulimit -i unlimited".
2392
Ingo Molnar45807a12007-07-15 23:40:10 -07002393 default: off.
2394
Matthew Garrettc22ab332012-03-05 14:59:10 -08002395 printk.always_kmsg_dump=
2396 Trigger kmsg_dump for cases other than kernel oops or
2397 panics
2398 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2399 default: disabled
2400
Randy Dunlape84845c2007-07-15 23:40:25 -07002401 printk.time= Show timing data prefixed to each printk message line
2402 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2403
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002404 processor.max_cstate= [HW,ACPI]
2405 Limit processor to maximum C-state
2406 max_cstate=9 overrides any DMI blacklist limit.
2407
2408 processor.nocst [HW,ACPI]
2409 Ignore the _CST method to determine C-states,
2410 instead using the legacy FADT method
2411
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002413 Format: [schedule,]<number>
2414 Param: "schedule" - profile schedule points.
2415 Param: <number> - step/bucket size as a power of 2 for
2416 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002417 Param: "sleep" - profile D-state sleeping (millisecs).
2418 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002419 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002420
Linus Torvalds1da177e2005-04-16 15:20:36 -07002421 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2422 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002423 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002424
Randy Dunlapa9913042005-10-23 12:57:11 -07002425 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2426 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2428 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002429 psmouse.resetafter= [HW,MOUSE]
2430 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002431 (0 = never).
2432 psmouse.resolution=
2433 [HW,MOUSE] Set desired mouse resolution, in dpi.
2434 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002435 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002436 0 = disabled, 1 = enabled (default).
2437
Matthew Garrettdee28e72011-07-21 16:57:55 -04002438 pstore.backend= Specify the name of the pstore backend to use
2439
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002441 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442
Kay Sieversdc8c8582007-08-15 12:25:38 +02002443 pty.legacy_count=
2444 [KNL] Number of legacy pty's. Overwrites compiled-in
2445 default number.
2446
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002447 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002448
Linus Torvalds1da177e2005-04-16 15:20:36 -07002449 r128= [HW,DRM]
2450
2451 raid= [HW,RAID]
2452 See Documentation/md.txt.
2453
Randy Dunlapa9913042005-10-23 12:57:11 -07002454 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002455 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002456
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002458 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002459
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002460 rcu_nocbs= [KNL,BOOT]
2461 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2462 the specified list of CPUs to be no-callback CPUs.
2463 Invocation of these CPUs' RCU callbacks will
2464 be offloaded to "rcuoN" kthreads created for
2465 that purpose. This reduces OS jitter on the
2466 offloaded CPUs, which can be useful for HPC and
2467 real-time workloads. It can also improve energy
2468 efficiency for asymmetric multiprocessors.
2469
Paul Gortmaker1b0048a2012-12-20 13:19:22 -08002470 rcu_nocb_poll [KNL,BOOT]
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -07002471 Rather than requiring that offloaded CPUs
2472 (specified by rcu_nocbs= above) explicitly
2473 awaken the corresponding "rcuoN" kthreads,
2474 make these kthreads poll for callbacks.
2475 This improves the real-time response for the
2476 offloaded CPUs by relieving them of the need to
2477 wake up the corresponding kthread, but degrades
2478 energy efficiency by requiring that the kthreads
2479 periodically wake up to do the polling.
2480
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07002481 rcutree.blimit= [KNL,BOOT]
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002482 Set maximum number of finished RCU callbacks to process
2483 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002484
Paul E. McKenneyf885b7f2012-04-23 15:52:53 -07002485 rcutree.fanout_leaf= [KNL,BOOT]
2486 Increase the number of CPUs assigned to each
2487 leaf rcu_node structure. Useful for very large
2488 systems.
2489
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07002490 rcutree.qhimark= [KNL,BOOT]
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002491 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002492 RCU callbacks over which batch limiting is disabled.
2493
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07002494 rcutree.qlowmark= [KNL,BOOT]
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002495 Set threshold of queued RCU callbacks below which
2496 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002497
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07002498 rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
2499 Suppress RCU CPU stall warning messages.
2500
2501 rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
2502 Set timeout for RCU CPU stall warning messages.
2503
Paul E. McKenneyd40011f2012-06-26 20:45:57 -07002504 rcutree.jiffies_till_first_fqs= [KNL,BOOT]
2505 Set delay from grace-period initialization to
2506 first attempt to force quiescent states.
2507 Units are jiffies, minimum value is zero,
2508 and maximum value is HZ.
2509
2510 rcutree.jiffies_till_next_fqs= [KNL,BOOT]
2511 Set delay between subsequent attempts to force
2512 quiescent states. Units are jiffies, minimum
2513 value is one, and maximum value is HZ.
2514
Paul E. McKenneydabb8aa2012-04-23 10:54:45 -07002515 rcutorture.fqs_duration= [KNL,BOOT]
2516 Set duration of force_quiescent_state bursts.
2517
2518 rcutorture.fqs_holdoff= [KNL,BOOT]
2519 Set holdoff time within force_quiescent_state bursts.
2520
2521 rcutorture.fqs_stutter= [KNL,BOOT]
2522 Set wait time between force_quiescent_state bursts.
2523
2524 rcutorture.irqreader= [KNL,BOOT]
2525 Test RCU readers from irq handlers.
2526
2527 rcutorture.n_barrier_cbs= [KNL,BOOT]
2528 Set callbacks/threads for rcu_barrier() testing.
2529
2530 rcutorture.nfakewriters= [KNL,BOOT]
2531 Set number of concurrent RCU writers. These just
2532 stress RCU, they don't participate in the actual
2533 test, hence the "fake".
2534
2535 rcutorture.nreaders= [KNL,BOOT]
2536 Set number of RCU readers.
2537
2538 rcutorture.onoff_holdoff= [KNL,BOOT]
2539 Set time (s) after boot for CPU-hotplug testing.
2540
2541 rcutorture.onoff_interval= [KNL,BOOT]
2542 Set time (s) between CPU-hotplug operations, or
2543 zero to disable CPU-hotplug testing.
2544
2545 rcutorture.shuffle_interval= [KNL,BOOT]
2546 Set task-shuffle interval (s). Shuffling tasks
2547 allows some CPUs to go into dyntick-idle mode
2548 during the rcutorture test.
2549
2550 rcutorture.shutdown_secs= [KNL,BOOT]
2551 Set time (s) after boot system shutdown. This
2552 is useful for hands-off automated testing.
2553
2554 rcutorture.stall_cpu= [KNL,BOOT]
2555 Duration of CPU stall (s) to test RCU CPU stall
2556 warnings, zero to disable.
2557
2558 rcutorture.stall_cpu_holdoff= [KNL,BOOT]
2559 Time to wait (s) after boot before inducing stall.
2560
2561 rcutorture.stat_interval= [KNL,BOOT]
2562 Time (s) between statistics printk()s.
2563
2564 rcutorture.stutter= [KNL,BOOT]
2565 Time (s) to stutter testing, for example, specifying
2566 five seconds causes the test to run for five seconds,
2567 wait for five seconds, and so on. This tests RCU's
2568 ability to transition abruptly to and from idle.
2569
2570 rcutorture.test_boost= [KNL,BOOT]
2571 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
2572 "Maybe" means test if the RCU implementation
2573 under test support RCU priority boosting.
2574
2575 rcutorture.test_boost_duration= [KNL,BOOT]
2576 Duration (s) of each individual boost test.
2577
2578 rcutorture.test_boost_interval= [KNL,BOOT]
2579 Interval (s) between each boost test.
2580
2581 rcutorture.test_no_idle_hz= [KNL,BOOT]
2582 Test RCU's dyntick-idle handling. See also the
2583 rcutorture.shuffle_interval parameter.
2584
2585 rcutorture.torture_type= [KNL,BOOT]
2586 Specify the RCU implementation to test.
2587
2588 rcutorture.verbose= [KNL,BOOT]
2589 Enable additional printk() statements.
2590
Olof Johanssonffdfc402005-09-06 15:17:19 -07002591 rdinit= [KNL]
2592 Format: <full_path>
2593 Run specified binary instead of /init from the ramdisk,
2594 used for early userspace startup. See initrd.
2595
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002596 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002598 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599
Paul Jackson46b6d942008-07-04 10:00:09 -07002600 relax_domain_level=
2601 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002602 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002603
Linus Torvalds1da177e2005-04-16 15:20:36 -07002604 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2605
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002606 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002607 Format: nn[KMG]
2608 Reserves a hole at the top of the kernel virtual
2609 address space.
2610
H. Peter Anvin9ea77bd2010-08-25 16:38:20 -07002611 reservelow= [X86]
2612 Format: nn[K]
2613 Set the amount of memory to reserve for BIOS at
2614 the bottom of the address space.
2615
Vivek Goyal7e962872006-09-27 01:50:44 -07002616 reset_devices [KNL] Force drivers to reset the underlying device
2617 during initialization.
2618
Randy Dunlapa9913042005-10-23 12:57:11 -07002619 resume= [SWSUSP]
2620 Specify the partition device for software suspend
Minho Ban2df83fa2012-05-14 21:45:31 +02002621 Format:
2622 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002624 resume_offset= [SWSUSP]
2625 Specify the offset from the beginning of the partition
2626 given by "resume=" at which the swap header is located,
2627 in <PAGE_SIZE> units (needed only for swap files).
2628 See Documentation/power/swsusp-and-swap-files.txt
2629
Barry Songf126f732011-10-10 23:38:41 +02002630 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2631 read the resume files
2632
Barry Song6f8d7022011-10-06 20:34:46 +02002633 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2634 Useful for devices that are detected asynchronously
2635 (e.g. USB and MMC devices).
2636
Bojan Smojverf996fc92010-09-09 23:06:23 +02002637 hibernate= [HIBERNATION]
2638 noresume Don't check if there's a hibernation image
2639 present during boot.
2640 nocompress Don't compress/decompress hibernation images.
2641
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08002642 retain_initrd [RAM] Keep initrd memory after extraction
2643
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 rhash_entries= [KNL,NET]
2645 Set number of hash buckets for route cache
2646
2647 riscom8= [HW,SERIAL]
2648 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2649
2650 ro [KNL] Mount root device read-only on boot
2651
2652 root= [KNL] Root filesystem
Will Drewryf2d34fd2011-08-03 16:21:08 -07002653 See name_to_dev_t comment in init/do_mounts.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654
2655 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2656 mount the root filesystem
2657
2658 rootflags= [KNL] Set root filesystem mount option string
2659
2660 rootfstype= [KNL] Set root filesystem type
2661
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002662 rootwait [KNL] Wait (indefinitely) for root device to show up.
2663 Useful for devices that are detected asynchronously
2664 (e.g. USB and MMC devices).
2665
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666 rw [KNL] Mount root device read-write on boot
2667
2668 S [KNL] Run init in single mode
2669
2670 sa1100ir [NET]
2671 See drivers/net/irda/sa1100_ir.c.
2672
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002674
Mike Travisf6630112009-11-17 18:22:15 -06002675 sched_debug [KNL] Enables verbose scheduler debug messages.
2676
Mike Galbraith5307c952012-05-08 12:20:58 +02002677 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
2678 xtime_lock contention on larger systems, and/or RCU lock
2679 contention on all systems with CONFIG_MAXSMP set.
2680 Format: { "0" | "1" }
2681 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
2682 1 -- enable.
2683 Note: increases power consumption, thus should only be
2684 enabled if running jitter sensitive (HPC/RT) workloads.
2685
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002686 security= [SECURITY] Choose a security module to enable at boot.
2687 If this boot parameter is not specified, only the first
2688 security module asking for security registration will be
2689 loaded. An invalid security module name will be treated
2690 as if no module has been chosen.
2691
2692 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002693 Format: { "0" | "1" }
2694 See security/selinux/Kconfig help text.
2695 0 -- disable.
2696 1 -- enable.
2697 Default value is set via kernel config option.
2698 If enabled at boot time, /selinux/disable can be used
2699 later to disable prior to initial policy load.
2700
John Johansenc1c124e2010-07-29 14:48:09 -07002701 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2702 Format: { "0" | "1" }
2703 See security/apparmor/Kconfig help text
2704 0 -- disable.
2705 1 -- enable.
2706 Default value is set via kernel config option.
2707
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002708 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002709
Linus Torvalds1da177e2005-04-16 15:20:36 -07002710 shapers= [NET]
2711 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002712
Yinghai Lub05f78f2008-08-22 01:32:50 -07002713 show_msr= [x86] show boot-time MSR settings
2714 Format: { <integer> }
2715 Show boot-time (BIOS-initialized) MSR settings.
2716 The parameter means the number of CPUs to show,
2717 for example 1 means boot CPU only.
2718
Linus Torvalds1da177e2005-04-16 15:20:36 -07002719 simeth= [IA-64]
2720 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002721
Linus Torvalds1da177e2005-04-16 15:20:36 -07002722 slram= [HW,MTD]
2723
David Rientjes3df1ccc2011-10-18 22:09:28 -07002724 slab_max_order= [MM, SLAB]
2725 Determines the maximum allowed order for slabs.
2726 A high setting may cause OOMs due to memory
2727 fragmentation. Defaults to 1 for systems with
2728 more than 32MB of RAM, 0 otherwise.
2729
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002730 slub_debug[=options[,slabs]] [MM, SLUB]
2731 Enabling slub_debug allows one to determine the
2732 culprit if slab objects become corrupted. Enabling
2733 slub_debug can create guard zones around objects and
2734 may poison objects when not in use. Also tracks the
2735 last alloc / free. For more information see
2736 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002737
2738 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002739 Determines the maximum allowed order for slabs.
2740 A high setting may cause OOMs due to memory
2741 fragmentation. For more information see
2742 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002743
2744 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002745 The minimum number of objects per slab. SLUB will
2746 increase the slab order up to slub_max_order to
2747 generate a sufficiently large slab able to contain
2748 the number of objects indicated. The higher the number
2749 of objects the smaller the overhead of tracking slabs
2750 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002751 For more information see Documentation/vm/slub.txt.
2752
2753 slub_min_order= [MM, SLUB]
Masanari Iida24775d62012-02-15 00:26:42 +09002754 Determines the minimum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002755 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002756 For more information see Documentation/vm/slub.txt.
2757
2758 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002759 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002760 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002761 allocs to different slabs. Debug options disable
2762 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002763 For more information see Documentation/vm/slub.txt.
2764
Linus Torvalds1da177e2005-04-16 15:20:36 -07002765 smart2= [HW]
2766 Format: <io1>[,<io2>[,...,<io8>]]
2767
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002768 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2769 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2770 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2771 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2772 smsc-ircc2.ircc_irq= [HW] IRQ line
2773 smsc-ircc2.ircc_dma= [HW] DMA channel
2774 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2775 0: Toshiba Satellite 1800 (GP data pin select)
2776 1: Fast pin select (default)
2777 2: ATC IRMode
2778
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002779 softlockup_panic=
2780 [KNL] Should the soft-lockup detector generate panics.
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07002781 Format: <integer>
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002782
Linus Torvalds1da177e2005-04-16 15:20:36 -07002783 sonypi.*= [HW] Sony Programmable I/O Control Device driver
Paul Bolle395cf962011-08-15 02:02:26 +02002784 See Documentation/laptops/sonypi.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -07002785
2786 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002787 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788
2789 spia_io_base= [HW,MTD]
2790 spia_fio_base=
2791 spia_pedr=
2792 spia_peddr=
2793
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002794 stacktrace [FTRACE]
2795 Enabled the stack tracer on boot up.
2796
Steven Rostedt762e1202011-12-19 22:01:00 -05002797 stacktrace_filter=[function-list]
2798 [FTRACE] Limit the functions that the stack tracer
2799 will trace at boot up. function-list is a comma separated
2800 list of functions. This list can be changed at run
2801 time by the stack_trace_filter file in the debugfs
2802 tracing directory. Note, this enables stack tracing
2803 and the stacktrace above is not needed.
2804
Linus Torvalds1da177e2005-04-16 15:20:36 -07002805 sti= [PARISC,HW]
2806 Format: <num>
2807 Set the STI (builtin display/keyboard on the HP-PARISC
2808 machines) console (graphic card) which should be used
2809 as the initial boot-console.
2810 See also comment in drivers/video/console/sticore.c.
2811
2812 sti_font= [HW]
2813 See comment in drivers/video/console/sticore.c.
2814
2815 stifb= [HW]
2816 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2817
Trond Myklebustcbf11072009-08-09 15:06:19 -04002818 sunrpc.min_resvport=
2819 sunrpc.max_resvport=
2820 [NFS,SUNRPC]
2821 SunRPC servers often require that client requests
2822 originate from a privileged port (i.e. a port in the
2823 range 0 < portnr < 1024).
2824 An administrator who wishes to reserve some of these
2825 ports for other uses may adjust the range that the
2826 kernel's sunrpc client considers to be privileged
2827 using these two parameters to set the minimum and
2828 maximum port values.
2829
Greg Banks42a7fc42007-03-06 01:42:23 -08002830 sunrpc.pool_mode=
2831 [NFS]
2832 Control how the NFS server code allocates CPUs to
2833 service thread pools. Depending on how many NICs
2834 you have and where their interrupts are bound, this
2835 option will affect which CPUs will do NFS serving.
2836 Note: this parameter cannot be changed while the
2837 NFS server is running.
2838
2839 auto the server chooses an appropriate mode
2840 automatically using heuristics
2841 global a single global pool contains all CPUs
2842 percpu one pool for each CPU
2843 pernode one pool for each NUMA node (equivalent
2844 to global on non-NUMA machines)
2845
Trond Myklebustcbf11072009-08-09 15:06:19 -04002846 sunrpc.tcp_slot_table_entries=
2847 sunrpc.udp_slot_table_entries=
2848 [NFS,SUNRPC]
2849 Sets the upper limit on the number of simultaneous
2850 RPC calls that can be sent from the client to a
2851 server. Increasing these values may allow you to
2852 improve throughput, but will also increase the
2853 amount of memory reserved for use by the client.
2854
Michal Hockoa42c3902010-11-24 12:57:08 -08002855 swapaccount[=0|1]
2856 [KNL] Enable accounting of swap in memory resource
2857 controller if no parameter or 1 is given or disable
2858 it if 0 is given (See Documentation/cgroups/memory.txt)
2859
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002861
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862 switches= [HW,M68k]
2863
Andi Kleene52eec12010-09-08 16:54:17 +02002864 sysfs.deprecated=0|1 [KNL]
2865 Enable/disable old style sysfs layout for old udev
2866 on older distributions. When this option is enabled
2867 very new udev will not work anymore. When this option
2868 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2869 in older udev will not work anymore.
2870 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2871 the kernel configuration.
2872
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002873 sysrq_always_enabled
2874 [KNL]
2875 Ignore sysrq setting - this boot parameter will
2876 neutralize any effect of /proc/sys/kernel/sysrq.
2877 Useful for debugging.
2878
Linus Torvalds1da177e2005-04-16 15:20:36 -07002879 tdfx= [HW,DRM]
2880
David Brownell77437fd2008-07-23 21:28:33 -07002881 test_suspend= [SUSPEND]
2882 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2883 standby suspend) as the system sleep state to briefly
2884 enter during system startup. The system is woken from
2885 this state using a wakeup-capable RTC alarm.
2886
Linus Torvalds1da177e2005-04-16 15:20:36 -07002887 thash_entries= [KNL,NET]
2888 Set number of hash buckets for TCP connection
2889
Len Brownf8707ec2007-08-12 00:12:54 -04002890 thermal.act= [HW,ACPI]
2891 -1: disable all active trip points in all thermal zones
2892 <degrees C>: override all lowest active trip points
2893
Len Brownc52a7412007-08-14 15:49:32 -04002894 thermal.crt= [HW,ACPI]
2895 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002896 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002897
Len Brownf5487142007-08-12 00:12:44 -04002898 thermal.nocrt= [HW,ACPI]
2899 Set to disable actions on ACPI thermal zone
2900 critical and hot trip points.
2901
Len Brown72b33ef2007-08-12 00:12:17 -04002902 thermal.off= [HW,ACPI]
2903 1: disable ACPI thermal control
2904
Len Browna70cdc52007-08-12 00:12:35 -04002905 thermal.psv= [HW,ACPI]
2906 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002907 <degrees C>: override all passive trip points to this
2908 value
Len Browna70cdc52007-08-12 00:12:35 -04002909
Len Brown730ff342007-08-12 00:12:26 -04002910 thermal.tzp= [HW,ACPI]
2911 Specify global default ACPI thermal zone polling rate
2912 <deci-seconds>: poll all this frequency
2913 0: no polling (default)
2914
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002915 threadirqs [KNL]
2916 Force threading of all interrupt handlers except those
Masanari Iida24775d62012-02-15 00:26:42 +09002917 marked explicitly IRQF_NO_THREAD.
Thomas Gleixner8d32a302011-02-23 23:52:23 +00002918
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002919 topology= [S390]
2920 Format: {off | on}
2921 Specify if the kernel should make use of the cpu
Sylvestre Ledruf65e51d2011-04-04 15:04:46 -07002922 topology information if the hardware supports this.
2923 The scheduler will make use of this information and
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002924 e.g. base its process migration decisions on it.
Heiko Carstensc9af3fa2010-10-25 16:10:43 +02002925 Default is on.
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002926
Linus Torvalds1da177e2005-04-16 15:20:36 -07002927 tp720= [HW,PS2]
2928
Rajiv Andrade225a9be2010-03-25 00:55:32 -03002929 tpm_suspend_pcr=[HW,TPM]
2930 Format: integer pcr id
2931 Specify that at suspend time, the tpm driver
2932 should extend the specified pcr with zeros,
2933 as a workaround for some chips which fail to
2934 flush the last written pcr on TPM_SaveState.
2935 This will guarantee that all the other pcrs
2936 are saved.
2937
Li Zefan9d612be2009-06-24 17:33:15 +08002938 trace_buf_size=nn[KMG]
2939 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002940
Li Zefan020e5f82009-07-01 10:47:05 +08002941 trace_event=[event-list]
2942 [FTRACE] Set and start specified trace events in order
2943 to facilitate early boot debugging.
2944 See also Documentation/trace/events.txt
2945
Steven Rostedt7bcfaf52012-11-01 22:56:07 -04002946 trace_options=[option-list]
2947 [FTRACE] Enable or disable tracer options at boot.
2948 The option-list is a comma delimited list of options
2949 that can be enabled or disabled just as if you were
2950 to echo the option name into
2951
2952 /sys/kernel/debug/tracing/trace_options
2953
2954 For example, to enable stacktrace option (to dump the
2955 stack trace of each event), add to the command line:
2956
2957 trace_options=stacktrace
2958
2959 See also Documentation/trace/ftrace.txt "trace options"
2960 section.
2961
Jiri Kosinafcf4d822012-03-21 16:34:02 -07002962 transparent_hugepage=
2963 [KNL]
2964 Format: [always|madvise|never]
2965 Can be used to control the default behavior of the system
2966 with respect to transparent hugepages.
2967 See Documentation/vm/transhuge.txt for more details.
2968
john stultzd3b8f882009-08-17 16:40:47 -07002969 tsc= Disable clocksource stability checks for TSC.
Alok Kataria395628e2008-10-24 17:22:01 -07002970 Format: <string>
2971 [x86] reliable: mark tsc clocksource as reliable, this
john stultzd3b8f882009-08-17 16:40:47 -07002972 disables clocksource verification at runtime, as well
2973 as the stability checks done at bootup. Used to enable
2974 high-resolution timer mode on older hardware, and in
2975 virtualized environment.
Venkatesh Pallipadie82b8e42010-10-04 17:03:20 -07002976 [x86] noirqtime: Do not use TSC to do irq accounting.
2977 Used to run time disable IRQ_TIME_ACCOUNTING on any
2978 platforms where RDTSC is slow and this accounting
2979 can add overhead.
Alok Kataria395628e2008-10-24 17:22:01 -07002980
Randy Dunlapa9913042005-10-23 12:57:11 -07002981 turbografx.map[2|3]= [HW,JOY]
2982 TurboGraFX parallel port interface
2983 Format:
2984 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002985 See also Documentation/input/joystick-parport.txt
2986
Christian Kujaub6935f82011-05-31 15:22:05 +00002987 udbg-immortal [PPC] When debugging early kernel crashes that
2988 happen after console_init() and before a proper
2989 console driver takes over, this boot options might
2990 help "seeing" what's going on.
2991
Eric Dumazetf86dcc52009-10-07 00:37:59 +00002992 uhash_entries= [KNL,NET]
2993 Set number of hash buckets for UDP/UDP-Lite connections
2994
Alan Stern5f8364b2006-12-05 16:29:55 -05002995 uhci-hcd.ignore_oc=
2996 [USB] Ignore overcurrent events (default N).
2997 Some badly-designed motherboards generate lots of
2998 bogus events, for ports that aren't wired to
2999 anything. Set this parameter to avoid log spamming.
3000 Note that genuine overcurrent events won't be
3001 reported either.
3002
Simon Arlotte3a61b02008-07-19 23:32:54 +01003003 unknown_nmi_panic
Randy Dunlap44a4dcf2011-04-04 15:02:24 -07003004 [X86] Cause panic on unknown NMI.
Simon Arlotte3a61b02008-07-19 23:32:54 +01003005
Carl-Daniel Hailfingerc4fc2342011-05-31 21:31:08 +02003006 usbcore.authorized_default=
3007 [USB] Default USB device authorization:
3008 (default -1 = authorized except for wireless USB,
3009 0 = not authorized, 1 = authorized)
3010
Alan Sternb5e795f2007-02-20 15:00:53 -05003011 usbcore.autosuspend=
3012 [USB] The autosuspend time delay (in seconds) used
3013 for newly-detected USB devices (default 2). This
3014 is the time required before an idle device will be
3015 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04003016 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05003017
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003018 usbcore.usbfs_snoop=
3019 [USB] Set to log all usbfs traffic (default 0 = off).
3020
3021 usbcore.blinkenlights=
3022 [USB] Set to cycle leds on hubs (default 0 = off).
3023
3024 usbcore.old_scheme_first=
3025 [USB] Start with the old device initialization
3026 scheme (default 0 = off).
3027
Alan Stern3f5eb8d2011-11-17 16:41:35 -05003028 usbcore.usbfs_memory_mb=
3029 [USB] Memory limit (in MB) for buffers allocated by
3030 usbfs (default = 16, 0 = max = 2047).
3031
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02003032 usbcore.use_both_schemes=
3033 [USB] Try the other device initialization scheme
3034 if the first one fails (default 1 = enabled).
3035
3036 usbcore.initial_descriptor_timeout=
3037 [USB] Specifies timeout for the initial 64-byte
3038 USB_REQ_GET_DESCRIPTOR request in milliseconds
3039 (default 5000 = 5.0 seconds).
3040
Linus Torvalds1da177e2005-04-16 15:20:36 -07003041 usbhid.mousepoll=
3042 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07003043
Alan Sternd4f373e2008-11-10 14:07:45 -05003044 usb-storage.delay_use=
3045 [UMS] The delay in seconds before a new device is
3046 scanned for Logical Units (default 5).
3047
3048 usb-storage.quirks=
3049 [UMS] A list of quirks entries to supplement or
3050 override the built-in unusual_devs list. List
3051 entries are separated by commas. Each entry has
3052 the form VID:PID:Flags where VID and PID are Vendor
3053 and Product ID values (4-digit hex numbers) and
3054 Flags is a set of characters, each corresponding
3055 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05003056 a = SANE_SENSE (collect more than 18 bytes
3057 of sense data);
Alan Sterna0bb1082009-12-07 16:39:16 -05003058 b = BAD_SENSE (don't collect more than 18
3059 bytes of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05003060 c = FIX_CAPACITY (decrease the reported
3061 device capacity by one sector);
Karl Relton51169012011-05-18 21:42:34 +01003062 d = NO_READ_DISC_INFO (don't use
3063 READ_DISC_INFO command);
3064 e = NO_READ_CAPACITY_16 (don't use
3065 READ_CAPACITY_16 command);
Alan Sternc838ea42008-12-15 10:40:06 -05003066 h = CAPACITY_HEURISTICS (decrease the
3067 reported device capacity by one
3068 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05003069 i = IGNORE_DEVICE (don't bind to this
3070 device);
3071 l = NOT_LOCKABLE (don't try to lock and
3072 unlock ejectable media);
3073 m = MAX_SECTORS_64 (don't transfer more
3074 than 64 sectors = 32 KB at a time);
Alan Stern21c13a42011-06-07 11:35:52 -04003075 n = INITIAL_READ10 (force a retry of the
3076 initial READ(10) command);
Alan Sternc838ea42008-12-15 10:40:06 -05003077 o = CAPACITY_OK (accept the capacity
3078 reported by the device);
Namjae Jeoneaa05df2012-07-07 23:05:28 -04003079 p = WRITE_CACHE (the device cache is ON
3080 by default);
Alan Sternd4f373e2008-11-10 14:07:45 -05003081 r = IGNORE_RESIDUE (the device reports
3082 bogus residue values);
3083 s = SINGLE_LUN (the device has only one
3084 Logical Unit);
3085 w = NO_WP_DETECT (don't test whether the
3086 medium is write-protected).
3087 Example: quirks=0419:aaf5:rl,0421:0433:rc
3088
Stephen Boydac1667d2011-08-13 12:34:50 -07003089 user_debug= [KNL,ARM]
3090 Format: <int>
3091 See arch/arm/Kconfig.debug help text.
3092 1 - undefined instruction events
3093 2 - system calls
3094 4 - invalid data aborts
3095 8 - SIGSEGV faults
3096 16 - SIGBUS faults
3097 Example: user_debug=31
3098
Ian Campbell14315592010-02-17 10:38:10 +00003099 userpte=
3100 [X86] Flags controlling user PTE allocations.
3101
3102 nohigh = do not allocate PTE pages in
3103 HIGHMEM regardless of setting
3104 of CONFIG_HIGHPTE.
3105
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05303106 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02003107 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07003108 vdso=1: enable VDSO (default)
3109 vdso=0: disable VDSO mapping
3110
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05303111 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01003112 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
3113 vdso32=1: enable 32-bit VDSO (default)
3114 vdso32=0: disable 32-bit VDSO mapping
3115
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09003116 vector= [IA-64,SMP]
3117 vector=percpu: enable percpu vector domain
3118
Linus Torvalds1da177e2005-04-16 15:20:36 -07003119 video= [FB] Frame buffer configuration
3120 See Documentation/fb/modedb.txt.
3121
Pawel Moll81a054c2012-05-09 18:30:16 +01003122 virtio_mmio.device=
3123 [VMMIO] Memory mapped virtio (platform) device.
3124
3125 <size>@<baseaddr>:<irq>[:<id>]
3126 where:
3127 <size> := size (can use standard suffixes
3128 like K, M and G)
3129 <baseaddr> := physical base address
3130 <irq> := interrupt number (as passed to
3131 request_irq())
3132 <id> := (optional) platform device id
3133 example:
3134 virtio_mmio.device=1K@0x100b0000:48:7
3135
3136 Can be used multiple times for multiple devices.
3137
Alan Coxcd4f0ef2007-07-31 00:37:59 -07003138 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05003139 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07003140 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003141 Use vga=ask for menu.
3142 This is actually a boot loader parameter; the value is
3143 passed to the kernel using a special protocol.
3144
Randy Dunlapa9913042005-10-23 12:57:11 -07003145 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07003146 size of <nn>. This can be used to increase the
3147 minimum size (128MB on x86). It can also be used to
3148 decrease the size and leave more room for directly
3149 mapped kernel RAM.
3150
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003151 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3152 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07003153
Peter Oberparleiter585c3042006-06-29 15:08:25 +02003154 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3155 Format: <command>
3156
3157 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3158 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07003159
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003160 vsyscall= [X86-64]
3161 Controls the behavior of vsyscalls (i.e. calls to
3162 fixed addresses of 0xffffffffff600x00 from legacy
3163 code). Most statically-linked binaries and older
3164 versions of glibc use these calls. Because these
3165 functions are at fixed addresses, they make nice
3166 targets for exploits that can control RIP.
3167
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003168 emulate [default] Vsyscalls turn into traps and are
3169 emulated reasonably safely.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003170
Andy Lutomirski2e57ae02011-11-07 16:33:41 -08003171 native Vsyscalls are native syscall instructions.
Andy Lutomirski3ae36652011-08-10 11:15:32 -04003172 This is a little bit faster than trapping
3173 and makes a few dynamic recompilers work
3174 better than they would in emulation mode.
3175 It also makes exploits much easier to write.
3176
3177 none Vsyscalls don't work at all. This makes
3178 them quite hard to use for exploits but
3179 might break your system.
3180
Clemens Ladisch9ea9a882009-12-15 16:45:39 -08003181 vt.cur_default= [VT] Default cursor shape.
3182 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3183 the parameters of the <Esc>[?A;B;Cc escape sequence;
3184 see VGA-softcursor.txt. Default: 2 = underline.
3185
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003186 vt.default_blu= [VT]
3187 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3188 Change the default blue palette of the console.
3189 This is a 16-member array composed of values
3190 ranging from 0-255.
3191
3192 vt.default_grn= [VT]
3193 Format: <green0>,<green1>,<green2>,...,<green15>
3194 Change the default green palette of the console.
3195 This is a 16-member array composed of values
3196 ranging from 0-255.
3197
3198 vt.default_red= [VT]
3199 Format: <red0>,<red1>,<red2>,...,<red15>
3200 Change the default red palette of the console.
3201 This is a 16-member array composed of values
3202 ranging from 0-255.
3203
3204 vt.default_utf8=
3205 [VT]
3206 Format=<0|1>
3207 Set system-wide default UTF-8 mode for all tty's.
3208 Default is 1, i.e. UTF-8 mode is enabled for all
3209 newly opened terminals.
3210
Matthew Garrettf6c06b62009-11-13 15:14:11 -05003211 vt.global_cursor_default=
3212 [VT]
3213 Format=<-1|0|1>
3214 Set system-wide default for whether a cursor
3215 is shown on new VTs. Default is -1,
3216 i.e. cursors will be created by default unless
3217 overridden by individual drivers. 0 will hide
3218 cursors, 1 will display them.
3219
Randy Dunlap4724ba572010-05-03 11:42:52 -07003220 watchdog timers [HW,WDT] For information on watchdog timers,
3221 see Documentation/watchdog/watchdog-parameters.txt
3222 or other driver-specific files in the
3223 Documentation/watchdog/ directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003224
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07003225 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3226 default x2apic cluster mode on platforms
3227 supporting x2apic.
3228
Jacob Panbb24c472009-09-02 07:37:17 -07003229 x86_mrst_timer= [X86-32,APBT]
3230 Choose timer option for x86 Moorestown MID platform.
3231 Two valid options are apbt timer only and lapic timer
3232 plus one apbt timer for broadcast timer.
3233 x86_mrst_timer=apbt_only | lapic_and_apbt
3234
Linus Torvalds1da177e2005-04-16 15:20:36 -07003235 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
3236 xd_geo= See header of drivers/block/xd.c.
3237
Stefano Stabellinic1c54132010-05-14 12:44:30 +01003238 xen_emul_unplug= [HW,X86,XEN]
3239 Unplug Xen emulated devices
3240 Format: [unplug0,][unplug1]
3241 ide-disks -- unplug primary master IDE devices
3242 aux-ide-disks -- unplug non-primary-master IDE devices
3243 nics -- unplug network devices
3244 all -- unplug all emulated devices (NICs and IDE disks)
Ian Campbell1dc7ce92010-08-23 11:59:29 +01003245 unnecessary -- unplugging emulated devices is
3246 unnecessary even if the host did not respond to
3247 the unplug protocol
Ian Campbellc93a4df2010-08-23 11:59:28 +01003248 never -- do not unplug even if version check succeeds
Stefano Stabellinic1c54132010-05-14 12:44:30 +01003249
Linus Torvalds1da177e2005-04-16 15:20:36 -07003250 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07003251 Format:
3252 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07003253
Randy Dunlapa9913042005-10-23 12:57:11 -07003254______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07003255
3256TODO:
3257
Linus Torvalds1da177e2005-04-16 15:20:36 -07003258 Add more DRM drivers.