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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Stefan Richtera901ebb2006-04-01 01:43:18 +020020This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
Stefan Richter6585fa82006-04-01 01:44:30 +020027The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100033 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020037 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080039 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070040 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070048 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070052 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070061 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070062 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070065 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070068 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070072 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070079 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070084 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090087 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070090 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700100 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
104
105In addition, the following text indicates that the option:
106
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
110
111Parameters denoted with BOOT are actually interpreted by the boot
112loader, and have no meaning to the kernel directly.
113Do not modify the syntax of boot loader parameters without extreme
114need or coordination with <Documentation/i386/boot.txt>.
115
Karsten Weiss55588702007-02-13 13:26:21 +0100116There are also arch-specific kernel-parameters not documented here.
117See for example <Documentation/x86_64/boot-options.txt>.
118
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120a trailing = on the name of any parameter states that that parameter will
121be entered as an environment variable, whereas its absence indicates that
122it will appear as a kernel argument readable via /proc/cmdline by programs
123running once the system is up.
124
jens m. noedler9c4751f2006-09-29 02:00:27 -0700125The number of kernel parameters is not limited, but the length of the
126complete command line (parameters including spaces etc.) is limited to
127a fixed number of characters. This limit depends on the architecture
128and is between 256 and 4096 characters. It is defined in the file
129./include/asm/setup.h as COMMAND_LINE_SIZE.
130
131
Bernhard Walle03d926f2007-03-06 02:29:44 -0800132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700134 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700139 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 strictly ACPI specification compliant.
141
Randy Dunlap53471122008-03-12 18:10:51 -0400142 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Len Browna1fdcc02007-03-11 03:26:14 -0400144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400148 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400149
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 acpi_sleep= [HW,ACPI] Sleep options
Shaohua Libdfe6b72008-07-23 21:28:41 -0700151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
Pavel Machek23b168d2008-02-05 19:27:12 +0100152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
160 used by default).
Randy Dunlapa9913042005-10-23 12:57:11 -0700161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700163 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
Randy Dunlapa9913042005-10-23 12:57:11 -0700165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
167 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
Randy Dunlapa9913042005-10-23 12:57:11 -0700169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
171 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
Randy Dunlapa9913042005-10-23 12:57:11 -0700173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
174 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 Format: <irq>,<irq>...
176
Randy Dunlapa9913042005-10-23 12:57:11 -0700177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 Format: <irq>,<irq>...
179
Len Brown67effe82007-07-26 00:50:06 -0400180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
181
Len Browna1f9e652006-01-25 23:47:36 -0500182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
184
Len Brownae00d812007-05-29 18:43:33 -0400185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
190 acpi_serialize [HW,ACPI] force serialization of AML methods
191
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
198 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
Zhang Ruif9891062007-04-24 13:53:22 +0800200 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700202 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Zhang Ruif9891062007-04-24 13:53:22 +0800217 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700219 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
234
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700235 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
239
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000240 agp= [AGP]
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
245
Chuck Ebbert66759a02005-09-12 18:49:25 +0200246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200250 The kernel tries to set a reasonable default.
251
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
255
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 ad1848= [HW,OSS]
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
258
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 advansys= [HW,SCSI]
260 See header of drivers/scsi/advansys.c.
261
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
264
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700268
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 aha152x= [HW,SCSI]
270 See Documentation/scsi/aha152x.txt.
271
272 aha1542= [HW,SCSI]
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
274
275 aic7xxx= [HW,SCSI]
276 See Documentation/scsi/aic7xxx.txt.
277
278 aic79xx= [HW,SCSI]
279 See Documentation/scsi/aic79xx.txt.
280
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
283 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
286 domain)
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
291
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
294 Format: <a>,<b>
295 See also Documentation/kernel/input/joystick.txt
296
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
301
Randy Dunlapa9913042005-10-23 12:57:11 -0700302 apc= [HW,SPARC]
303 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 Format: noidle
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
308
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700314
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700316 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
320
321 ataflop= [HW,M68k]
322
323 atarimouse= [HW,MOUSE] Atari Mouse
324
325 atascsi= [HW,SCSI] Atari SCSI
326
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
329
330 atkbd.reset= [HW] Reset keyboard during initialization
331
Randy Dunlapa9913042005-10-23 12:57:11 -0700332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
336 keyboards
337
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700340
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343
344 autotest [IA64]
345
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 baycom_epp= [HW,AX25]
347 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700348
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
350 Format: <io>,<mode>
351 See header of drivers/net/hamradio/baycom_par.c.
352
Randy Dunlapa9913042005-10-23 12:57:11 -0700353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
357
Randy Dunlapa9913042005-10-23 12:57:11 -0700358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
362
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
365 no delay (0).
366 Format: integer
367
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700371 bttv.radio= Most important insmod options are available as
372 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
375
376 BusLogic= [HW,SCSI]
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
379
380 c101= [NET] Moxa C101 synchronous serial card
381
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
388
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
394
James Morris20510f22007-10-16 23:31:32 -0700395 capability.disable=
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
400
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403
Paul Menage8bab8dd2008-04-04 14:29:57 -0700404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
407
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700415 Value can be changed at runtime via
416 /selinux/checkreqprot.
417
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100418 cio_ignore= [S390]
419 See Documentation/s390/CommonIO for details.
420
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700422 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200423 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700424 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200425 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 Format: { pit | tsc | cyclone | pmtmr }
427
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700428 clocksource= [GENERIC_TIME] Override the default clocksource
429 Format: <string>
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
433 the platform:
434 [all] jiffies (this is the base, fallback clocksource)
435 [ACPI] acpi_pm
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
438 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700439 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700440 scx200_hrt on Geode; cyclone on IBM x440
441 [MIPS] MIPS
442 [PARISC] cr16
443 [S390] tod
444 [SH] SuperH
445 [SPARC64] tick
446 [X86-64] hpet,tsc
447
Andi Kleenac72e782008-01-30 13:33:21 +0100448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
453 ones should be.
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
459 some critical bits.
460
Arjan van de Vena25bd942008-01-30 13:33:08 +0100461 code_bytes [IA32/X86_64] How many bytes of object code to print
462 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100463 Range: 0 - 8192
464 Default: 64
465
Andi Kleenf9262c12006-03-08 17:57:25 -0800466 disable_8254_timer
467 enable_8254_timer
468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
469 over the 8254 in addition to over the IO-APIC. The
470 kernel tries to set a sensible default.
471
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100475 force: allow force enabled of undocumented chips (ICH4,
476 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700479 Format:
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
483 Format: <io>[,<irq>]
484
Randy Dunlapa9913042005-10-23 12:57:11 -0700485 com90xx= [HW,NET]
486 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 Format: <io>[,<irq>[,<memstart>]]
488
489 condev= [HW,S390] console device
490 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700491
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 console= [KNL] Output console device and options.
493
494 tty<n> Use the virtual console device <n>.
495
496 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800497 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800504 See Documentation/serial-console.txt for more
505 information. See
506 Documentation/networking/netconsole.txt for an
507 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
515
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
518 console=brl,ttyS0
519 For now, only VisioBraille is supported.
520
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
527
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700528 no_console_suspend
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
537
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700539 Format:
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
545
Bernhard Wallefb391592007-10-18 23:41:02 -0700546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
552
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 cs4232= [HW,OSS]
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
555
556 cs89x0_dma= [HW,NET]
557 Format: <dma>
558
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700561
Randy Dunlapa9913042005-10-23 12:57:11 -0700562 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 See header of drivers/s390/block/dasd_devmap.c.
564
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
569
570 debug [KNL] Enable kernel debugging (events log level).
571
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700572 debug_locks_verbose=
573 [KNL] verbose self-tests
574 Format=<0|1>
575 Print debugging info while doing the locking API
576 self-tests.
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
580
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700581 debug_objects [KNL] Enable object debugging
582
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200583 debugpat [X86] Enable PAT debugging
584
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200585 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
588
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000589 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
593 ranging from 0-255.
594
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000595 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
599 ranging from 0-255.
600
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000601 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
606
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000607 vt.default_utf8=
608 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700609 Format=<0|1>
610 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700613
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 dhash_entries= [KNL]
615 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700616
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 digi= [HW,SERIAL]
618 IO parameters + enable/disable command.
619
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
623
Yinghai Lu95ffa242008-04-29 03:52:33 -0700624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
629
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
633
634 mtrr_gran_size=nn[KMG] [X86]
Yinghai Lu12031a62008-05-02 02:40:22 -0700635 Used for mtrr cleanup. It is granularity of mtrr block.
636 Default is 1.
637 Large value could prevent small alignment from
638 using up MTRRs.
639
640 mtrr_spare_reg_nr=n [X86]
641 Format: <integer>
642 Range: 0,7 : spare reg number
643 Default : 1
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700646
Yinghai Lu093af8d2008-01-30 13:33:32 +0100647 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 dmasound= [HW,OSS] Sound subsystem buffers
654
655 dscc4.setup= [NET]
656
657 dtc3181e= [HW,SCSI]
658
Robin Getz0ae53642007-10-09 17:24:49 +0800659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
662
Randy Dunlapa9913042005-10-23 12:57:11 -0700663 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 takes over.
665
666 Only vga or serial at a time, not both.
667
668 Currently only ttyS0 and ttyS1 are supported.
669
670 Interaction with the standard serial driver is not
671 very good.
672
673 The VGA output is eventually overwritten by the real
674 console.
675
676 eata= [HW,SCSI]
677
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700679 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
683
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700684 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
688 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
692
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700693 elfcorehdr= [X86-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700694 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
699 enforcing [SELINUX] Set initial enforcing status.
700 Format: {"0" | "1"}
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
704 Default value is 0.
705 Value can be changed at runtime via /selinux/enforce.
706
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 es1371= [HW,OSS]
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700710
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
714
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
716 Format: <io>[,<irq>]
717
Akinobu Mitade1ba092006-12-08 02:39:42 -0800718 failslab=
719 fail_page_alloc=
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 fd_mcs= [HW,SCSI]
726 See header of drivers/scsi/fd_mcs.c.
727
728 fdomain= [HW,SCSI]
729 See header of drivers/scsi/fdomain.c.
730
731 floppy= [HW]
732 See Documentation/floppy.txt.
733
Alex Chiangf13ae302008-05-08 14:03:23 -0600734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 gamecon.map[2|3]=
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
745
746 gamma= [HW,DRM]
747
Yinghai Luaaf23042008-01-30 13:33:09 +0100748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
749 Format: off | on
750 default: on
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 gdth= [HW,SCSI]
753 See header of drivers/scsi/gdth.c.
754
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
757
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 gvp11= [HW,SCSI]
759
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700763 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
766
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
769
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
774
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
777 Default: "on"
778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 hisax= [HW,ISDN]
780 See Documentation/isdn/README.HiSax.
781
Andi Kleenb4718e62008-07-23 21:27:51 -0700782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700791 default_hugepagesz=
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
797 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200800 i8042.dumbkbd [HW] Pretend that controller can only read data from
801 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 (Don't attempt to blink the leds)
803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500804 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400805 i8042.noloop [HW] Disable the AUX Loopback command while probing
806 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 i8042.nomux [HW] Don't check presence of an active multiplexing
808 controller
809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
810 controllers
811 i8042.panicblink=
812 [HW] Frequency with which keyboard LEDs should blink
813 when kernel panics (default is 0.5 sec)
814 i8042.reset [HW] Reset the controller during init and cleanup
815 i8042.unlock [HW] Unlock (ignore) the keylock
816
817 i810= [HW,DRM]
818
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
820 indicates that the driver is running on unsupported
821 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
823 does not match list of supported models.
824 i8k.power_status
825 [HW] Report power status in /proc/i8k
826 (disabled by default)
827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
828 capability is set.
829
830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
831 See Documentation/mca.txt.
832
833 icn= [HW,ISDN]
834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
835
836 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200837 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100838 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100841 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
Andi Kleenf039b752007-05-02 19:27:12 +0200843 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800844 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200845 Poll forces a polling idle loop that can slightly improves the performance
846 of waking up a idle CPU, but will use a lot of power and make the system
847 run hot. Not recommended.
848 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
849 to not use it because it doesn't save as much power as a normal idle
850 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
851 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800852 idle=halt. Halt is forced to be used for CPU idle.
853 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800854 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700855
Denis Cheng594765a2008-02-06 02:57:49 +0100856 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
857 Claim all unknown PCI IDE storage controllers.
858
Ingo Molnar792908222006-12-06 20:40:51 -0800859 ignore_loglevel [KNL]
860 Ignore loglevel setting - this will print /all/
861 kernel messages to the console. Useful for debugging.
862
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 ihash_entries= [KNL]
864 Set number of hash buckets for inode cache.
865
866 in2000= [HW,SCSI]
867 See header of drivers/scsi/in2000.c.
868
869 init= [KNL]
870 Format: <full_path>
871 Run specified binary instead of /sbin/init as init
872 process.
873
874 initcall_debug [KNL] Trace initcalls as they are executed. Useful
875 for working out where the kernel is dying during
876 startup.
877
878 initrd= [BOOT] Specify the location of the initial ramdisk
879
880 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
881 Format: <irq>
882
883 inttest= [IA64]
884
Pavel Machekb552da82008-03-19 15:58:11 +0100885 iommu= [x86]
886 off
887 force
888 noforce
889 biomerge
890 panic
891 nopanic
892 merge
893 nomerge
894 forcesac
895 soft
896
897
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700898 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
899 off
900 Disable intel iommu driver.
901 igfx_off [Default Off]
902 By default, gfx is mapped as normal device. If a gfx
903 device has a dedicated DMAR unit, the DMAR unit is
904 bypassed by not enabling DMAR with this option. In
905 this case, gfx device will use physical address for
906 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700907 forcedac [x86_64]
908 With this option iommu will not optimize to look
909 for io virtual address below 32 bit forcing dual
910 address cycle on pci bus for cards supporting greater
911 than 32 bit addressing. The default is to look
912 for translation below 32 bit and if not available
913 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800914 strict [Default Off]
915 With this option on every unmap_single operation will
916 result in a hardware IOTLB flush operation as opposed
917 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700918
Rene Hermanb02aae92008-01-30 13:30:05 +0100919 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100920 0x80
921 Standard port 0x80 based delay
922 0xed
923 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100924 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100925 Simple two microseconds delay
926 none
927 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100928
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 io7= [HW] IO7 for Marvel based alpha systems
930 See comment before marvel_specify_io7 in
931 arch/alpha/kernel/core_marvel.c.
932
933 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400934 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
936 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700937 See comment before ip2_setup() in
938 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939
940 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
941 See header of drivers/scsi/ips.c.
942
Simon Horman72c4a132006-09-13 19:57:18 -0700943 ports= [IP_VS_FTP] IPVS ftp helper module
944 Default is 21.
945 Up to 8 (IP_VS_APP_MAX_PORTS) ports
946 may be specified.
947 Format: <port>,<port>....
948
Alan Cox200803d2005-06-28 20:45:18 -0700949 irqfixup [HW]
950 When an interrupt is not handled search all handlers
951 for it. Intended to get systems with badly broken
952 firmware running.
953
954 irqpoll [HW]
955 When an interrupt is not handled search all handlers
956 for it. Also check all handlers each timer
957 interrupt. Intended to get systems with badly broken
958 firmware running.
959
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700961 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962
963 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800964 Format:
965 <cpu number>,...,<cpu number>
966 or
967 <cpu number>-<cpu number> (must be a positive range in ascending order)
968 or a mixture
969 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 This option can be used to specify one or more CPUs
971 to isolate from the general SMP balancing and scheduling
972 algorithms. The only way to move a process onto or off
973 an "isolated" CPU is via the CPU affinity syscalls.
974 <cpu number> begins at 0 and the maximum value is
975 "number of CPUs in system - 1".
976
977 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700978 alternative -- manually setting the CPU mask of all
979 tasks in the system -- can cause problems and
980 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
Randy Dunlapa9913042005-10-23 12:57:11 -0700982 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983
984 js= [HW,JOY] Analog joystick
985 See Documentation/input/joystick.txt.
986
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700987 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -0700988 specifies the amount of memory usable by the kernel
989 for non-movable allocations. The requested amount is
990 spread evenly throughout all nodes in the system. The
991 remaining memory in each node is used for Movable
992 pages. In the event, a node is too small to have both
993 kernelcore and Movable pages, kernelcore pages will
994 take priority and other nodes will have a larger number
995 of kernelcore pages. The Movable zone is used for the
996 allocation of pages that may be reclaimed or moved
997 by the page migration subsystem. This means that
998 HugeTLB pages may not be allocated from this zone.
999 Note that allocations like PTEs-from-HighMem still
1000 use the HighMem zone if it exists, and the Normal
1001 zone if it does not.
1002
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001003 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001004 is similar to kernelcore except it specifies the
1005 amount of memory used for migratable allocations.
1006 If both kernelcore and movablecore is specified,
1007 then kernelcore will be at *least* the specified
1008 value but may be more. If movablecore on its own
1009 is specified, the administrator must be careful
1010 that the amount of memory usable for all allocations
1011 is not too small.
1012
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 keepinitrd [HW,ARM]
1014
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001015 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016 in oops dumps.
1017
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001018 kgdboc= [HW] kgdb over consoles.
1019 Requires a tty driver that supports console polling.
1020 (only serial suported for now)
1021 Format: <serial_device>[,baud]
1022
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 l2cr= [PPC]
1024
Robert Brosea78bfbf2008-03-29 07:20:23 +11001025 l3cr= [PPC]
1026
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001027 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001028 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001030 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001031 C2 power state.
1032
FD Camifcb71f62008-01-06 19:08:56 +01001033 libata.dma= [LIBATA] DMA control
1034 libata.dma=0 Disable all PATA and SATA DMA
1035 libata.dma=1 PATA and SATA Disk DMA only
1036 libata.dma=2 ATAPI (CDROM) DMA only
1037 libata.dma=4 Compact Flash DMA only
1038 Combinations also work, so libata.dma=3 enables DMA
1039 for disks and CDROMs, but not CFs.
1040
Dave Jones78e70c22007-09-27 11:50:13 -04001041 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1042 when set.
1043 Format: <int>
1044
Tejun Heo33267322008-02-13 09:15:09 +09001045 libata.force= [LIBATA] Force configurations. The format is comma
1046 separated list of "[ID:]VAL" where ID is
1047 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1048 matching port, link or device. Basically, it matches
1049 the ATA ID string printed on console by libata. If
1050 the whole ID part is omitted, the last PORT and DEVICE
1051 values are used. If ID hasn't been specified yet, the
1052 configuration applies to all ports, links and devices.
1053
1054 If only DEVICE is omitted, the parameter applies to
1055 the port and all links and devices behind it. DEVICE
1056 number of 0 either selects the first device or the
1057 first fan-out link behind PMP device. It does not
1058 select the host link. DEVICE number of 15 selects the
1059 host link and device attached to it.
1060
1061 The VAL specifies the configuration to force. As long
1062 as there's no ambiguity shortcut notation is allowed.
1063 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1064 The following configurations can be forced.
1065
1066 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1067 Any ID with matching PORT is used.
1068
1069 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1070
1071 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1072 udma[/][16,25,33,44,66,100,133] notation is also
1073 allowed.
1074
1075 * [no]ncq: Turn on or off NCQ.
1076
1077 If there are multiple matching configurations changing
1078 the same attribute, the last one is used.
1079
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 load_ramdisk= [RAM] List of ramdisks to load from floppy
1081 See Documentation/ramdisk.txt.
1082
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001083 lockd.nlm_grace_period=P [NFS] Assign grace period.
1084 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001086 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1087 Format: <integer>
1088
1089 lockd.nlm_timeout=T [NFS] Assign timeout value.
1090 Format: <integer>
1091
1092 lockd.nlm_udpport=M [NFS] Assign UDP port.
1093 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094
1095 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1096 Format: <irq>
1097
1098 loglevel= All Kernel Messages with a loglevel smaller than the
1099 console loglevel will be printed to the console. It can
1100 also be changed with klogd or other programs. The
1101 loglevels are defined as follows:
1102
1103 0 (KERN_EMERG) system is unusable
1104 1 (KERN_ALERT) action must be taken immediately
1105 2 (KERN_CRIT) critical conditions
1106 3 (KERN_ERR) error conditions
1107 4 (KERN_WARNING) warning conditions
1108 5 (KERN_NOTICE) normal but significant condition
1109 6 (KERN_INFO) informational
1110 7 (KERN_DEBUG) debug-level messages
1111
1112 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001113 Format: { n | nk | nM }
1114 n must be a power of two. The default size
1115 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
Randy Dunlapaccaa242007-10-16 01:29:37 -07001117 logo.nologo [FB] Disables display of the built-in Linux logo.
1118 This may be used to provide more screen space for
1119 kernel log messages and is useful when debugging
1120 kernel boot problems.
1121
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 lp=0 [LP] Specify parallel ports to use, e.g,
1123 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1124 lp=reset first parallel port). 'lp=0' disables the
1125 lp=auto printer driver. 'lp=reset' (which can be
1126 specified in addition to the ports) causes
1127 attached printers to be reset. Using
1128 lp=port1,port2,... specifies the parallel ports
1129 to associate lp devices with, starting with
1130 lp0. A port specification may be 'none' to skip
1131 that lp device, or a parport name such as
1132 'parport0'. Specifying 'lp=auto' instead of a
1133 port specification list means that device IDs
1134 from each port should be examined, to see if
1135 an IEEE 1284-compliant printer is attached; if
1136 so, the driver will manage that printer.
1137 See also header of drivers/char/lp.c.
1138
1139 lpj=n [KNL]
1140 Sets loops_per_jiffy to given constant, thus avoiding
1141 time-consuming boot-time autodetection (up to 250 ms per
1142 CPU). 0 enables autodetection (default). To determine
1143 the correct value for your kernel, boot with normal
1144 autodetection and see what value is printed. Note that
1145 on SMP systems the preset will be applied to all CPUs,
1146 which is likely to cause problems if your CPUs need
1147 significantly divergent settings. An incorrect value
1148 will cause delays in the kernel to be wrong, leading to
1149 unpredictable I/O errors and other breakage. Although
1150 unlikely, in the extreme case this might damage your
1151 hardware.
1152
1153 ltpc= [NET]
1154 Format: <io>,<irq>,<dma>
1155
Randy Dunlapa9913042005-10-23 12:57:11 -07001156 mac5380= [HW,SCSI] Format:
1157 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158
Randy Dunlapa9913042005-10-23 12:57:11 -07001159 machvec= [IA64] Force the use of a particular machine-vector
1160 (machvec) in a generic kernel.
1161 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162
Randy Dunlapa9913042005-10-23 12:57:11 -07001163 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 be mounted
1165 Format: <1-256>
1166
1167 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001168 should make use of. maxcpus=n : n >= 0 limits the
1169 kernel to using 'n' processors. n=0 is a special case,
1170 it is equivalent to "nosmp", which also disables
1171 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
Bob Picco2b2c3752005-06-29 18:00:00 -07001173 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1174 equal to this physical address is ignored.
1175
Randy Dunlapa9913042005-10-23 12:57:11 -07001176 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 Should be between 1 and 2^32-1.
1178
1179 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001180 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 Should be between 1 and 16384.
1182
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 mcatest= [IA-64]
1184
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001185 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186
Andi Kleen909dd322007-10-17 18:04:38 +02001187 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1188
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 md= [HW] RAID subsystems devices and level
1190 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001191
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 mdacon= [MDA]
1193 Format: <first>,<last>
1194 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001195
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1197 Amount of memory to be used when the kernel is not able
1198 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001199 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 address space collisions. Without memmap= PCI devices
1201 could be placed at addresses belonging to unused RAM.
1202
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001203 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 memory.
1205
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001206 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 E820 memory map, as specified by the user.
1208 Such memmap=exactmap lines can be constructed based on
1209 BIOS output or other requirements. See the memmap=nn@ss
1210 option description.
1211
1212 memmap=nn[KMG]@ss[KMG]
1213 [KNL] Force usage of a specific region of memory
1214 Region of memory to be used, from ss to ss+nn.
1215
1216 memmap=nn[KMG]#ss[KMG]
1217 [KNL,ACPI] Mark specific memory as ACPI data.
1218 Region of memory to be used, from ss to ss+nn.
1219
1220 memmap=nn[KMG]$ss[KMG]
1221 [KNL,ACPI] Mark specific memory as reserved.
1222 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001223 Example: Exclude memory from 0x18690000-0x1869ffff
1224 memmap=64K$0x18690000
1225 or
1226 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001228 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001229 Format: <integer>
1230 range: 0,4 : pattern number
1231 default : 0 <disable>
1232
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 meye.*= [HW] Set MotionEye Camera parameters
1234 See Documentation/video4linux/meye.txt.
1235
Andres Salomon8f368812007-10-12 23:04:06 +02001236 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1237 Multi-Function General Purpose Timers on AMD Geode
1238 platforms.
1239
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001240 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1241 the BIOS has incorrectly applied a workaround. TinyBIOS
1242 version 0.98 is known to be affected, 0.99 fixes the
1243 problem by letting the user disable the workaround.
1244
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 mga= [HW,DRM]
1246
Mel Gorman6b74ab92008-07-23 21:26:49 -07001247 mminit_loglevel=
1248 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1249 parameter allows control of the logging verbosity for
1250 the additional memory initialisation checks. A value
1251 of 0 disables mminit logging and a level of 4 will
1252 log everything. Information is printed at KERN_DEBUG
1253 so loglevel=8 may also need to be specified.
1254
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 mousedev.tap_time=
1256 [MOUSE] Maximum time between finger touching and
1257 leaving touchpad surface for touch to be considered
1258 a tap and be reported as a left button click (for
1259 touchpads working in absolute mode only).
1260 Format: <msecs>
1261 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1262 reporting absolute coordinates, such as tablets
1263 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1264 reporting absolute coordinates, such as tablets
1265
1266 mpu401= [HW,OSS]
1267 Format: <io>,<irq>
1268
1269 MTD_Partition= [MTD]
1270 Format: <name>,<region-number>,<size>,<offset>
1271
Randy Dunlapa9913042005-10-23 12:57:11 -07001272 MTD_Region= [MTD] Format:
1273 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274
1275 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001276 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277
Ben Dooks9db829f2008-07-03 11:24:29 +01001278 mtdset= [ARM]
1279 ARM/S3C2412 JIVE boot control
1280
1281 See arch/arm/mach-s3c2412/mach-jive.c
1282
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001284 [HW] Make the MicroTouch USB driver use raw coordinates
1285 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286
1287 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1288
1289 NCR_D700= [HW,SCSI]
1290 See header of drivers/scsi/NCR_D700.c.
1291
1292 ncr5380= [HW,SCSI]
1293
1294 ncr53c400= [HW,SCSI]
1295
1296 ncr53c400a= [HW,SCSI]
1297
1298 ncr53c406a= [HW,SCSI]
1299
1300 ncr53c8xx= [HW,SCSI]
1301
1302 netdev= [NET] Network devices parameters
1303 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1304 Note that mem_start is often overloaded to mean
1305 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001306 This usage is only documented in each driver source
1307 file if at all.
1308
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001309 nf_conntrack.acct=
1310 [NETFILTER] Enable connection tracking flow accounting
1311 0 to disable accounting
1312 1 to enable accounting
1313 Default value depends on CONFIG_NF_CT_ACCT that is
1314 going to be removed in 2.6.29.
1315
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001317 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318
1319 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001320 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321
Trond Myklebusta72b4422006-01-03 09:55:41 +01001322 nfs.callback_tcpport=
1323 [NFS] set the TCP port on which the NFSv4 callback
1324 channel should listen.
1325
Trond Myklebust58df0952006-01-03 09:55:57 +01001326 nfs.idmap_cache_timeout=
1327 [NFS] set the maximum lifetime for idmapper cache
1328 entries.
1329
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001330 nfs.enable_ino64=
1331 [NFS] enable 64-bit inode numbers.
1332 If zero, the NFS client will fake up a 32-bit inode
1333 number for the readdir() and stat() syscalls instead
1334 of returning the full 64-bit number.
1335 The default is to return 64-bit inode numbers.
1336
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001337 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1338 when a NMI is triggered.
1339 Format: [state][,regs][,debounce][,die]
1340
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001341 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001343 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344 emulation library even if a 387 maths coprocessor
1345 is present.
1346
Christoph Lameterc1aee212007-05-31 00:40:47 -07001347 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1348 caches in the slab allocator. Saves per-node memory,
1349 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001350
Randy Dunlapa9913042005-10-23 12:57:11 -07001351 noalign [KNL,ARM]
1352
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 noapic [SMP,APIC] Tells the kernel to not make use of any
1354 IOAPICs that may be present in the system.
1355
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 nobats [PPC] Do not use BATs for mapping kernel lowmem
1357 on "Classic" PPC cores.
1358
1359 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001360
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001361 nodelayacct [KNL] Disable per-task delay accounting
1362
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1364
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001365 noefi [X86-32,X86-64] Disable EFI runtime services support.
1366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 noexec [IA-64]
1368
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001369 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001370 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001372 noexec=off: disable non-executable mappings
1373
1374 noexec32 [X86-64]
1375 This affects only 32-bit executables.
1376 noexec32=on: enable non-executable mappings (default)
1377 read doesn't imply executable mappings
1378 noexec32=off: disable non-executable mappings
1379 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001381 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001382 register save and restore. The kernel will only save
1383 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384
Andi Kleen191679f2008-01-30 13:33:21 +01001385 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1386
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001388
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001389 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 instruction doesn't work correctly and not to
1391 use it.
1392
1393 nohalt [IA-64] Tells the kernel not to use the power saving
1394 function PAL_HALT_LIGHT when idle. This increases
1395 power-consumption. On the positive side, it reduces
1396 interrupt wake-up latency, which may improve performance
1397 in certain environments such as networked servers or
1398 real-time systems.
1399
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001400 nohz= [KNL] Boottime enable/disable dynamic ticks
1401 Valid arguments: on, off
1402 Default: on
1403
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001404 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
Zachary Amsden8542b202006-12-07 02:14:09 +01001405
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001406 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407 disable unhandled interrupt sources.
1408
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001409 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001410 broken timer IRQ sources.
1411
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 noisapnp [ISAPNP] Disables ISA PnP code.
1413
1414 noinitrd [RAM] Tells the kernel not to load any configured
1415 initial RAM disk.
1416
1417 nointroute [IA-64]
1418
Tony Luck0aa366f2007-07-20 11:22:30 -07001419 nojitter [IA64] Disables jitter checking for ITC timers.
1420
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001421 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001423 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001424
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 noltlbs [PPC] Do not use large page/tlb entries for kernel
1426 lowmem mapping on PPC40x.
1427
Horms312f1f02006-02-22 09:57:55 +09001428 nomca [IA-64] Disable machine check abort handling
1429
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001430 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001431
Andres Salomon83d73842007-10-12 23:04:06 +02001432 nomfgpt [X86-32] Disable Multi-Function General Purpose
1433 Timer usage (for AMD Geode machines).
1434
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001435 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001436
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001437 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001438 with UP alternatives
1439
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 noresidual [PPC] Don't use residual data on PReP machines.
1441
Randy Dunlapa9913042005-10-23 12:57:11 -07001442 noresume [SWSUSP] Disables resume and restores original swap
1443 space.
1444
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 no-scroll [VGA] Disables scrollback.
1446 This is required for the Braillex ib80-piezo Braille
1447 reader made by F.H. Papenmeier (Germany).
1448
1449 nosbagart [IA-64]
1450
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001451 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001452
Len Brown61ec7562007-08-16 03:34:22 -04001453 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1454 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455
Dave Jones97842212007-07-15 23:41:05 -07001456 nosoftlockup [KNL] Disable the soft-lockup detector.
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 nosync [HW,M68K] Disables sync negotiation for all devices.
1459
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001460 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461
1462 nousb [USB] Disable the USB subsystem
1463
1464 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001465
Fenghua Yua6c75b862008-03-14 13:57:08 -07001466 nptcg= [IA64] Override max number of concurrent global TLB
1467 purges which is reported from either PAL_VM_SUMMARY or
1468 SAL PALO.
1469
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001470 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1471 one of ['zone', 'node', 'default'] can be specified
1472 This can be set from sysctl after boot.
1473 See Documentation/sysctl/vm.txt for details.
1474
Dave Jonesa61c2d72006-01-07 23:18:19 +00001475 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1476
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001477 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1478 Rather than timing out after 20 ms if an EC
1479 command is not properly ACKed, override the length
1480 of the timeout. We have interrupts disabled while
1481 waiting for the ACK, so if this is set too high
1482 interrupts *may* be lost!
1483
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 opl3= [HW,OSS]
1485 Format: <io>
1486
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 oprofile.timer= [HW]
1488 Use timer interrupt instead of performance counters
1489
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 osst= [HW,SCSI] SCSI Tape Driver
1491 Format: <buffer_size>,<write_threshold>
1492 See also Documentation/scsi/st.txt.
1493
1494 panic= [KNL] Kernel behaviour on panic
1495 Format: <timeout>
1496
1497 parkbd.port= [HW] Parallel port number the keyboard adapter is
1498 connected to, default is 0.
1499 Format: <parport#>
1500 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1501 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001502 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503
Randy Dunlapa9913042005-10-23 12:57:11 -07001504 parport= [HW,PPT] Specify parallel ports. 0 disables.
1505 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1506 Use 'auto' to force the driver to use any
1507 IRQ/DMA settings detected (the default is to
1508 ignore detected IRQ/DMA settings because of
1509 possible conflicts). You can specify the base
1510 address, IRQ, and DMA settings; IRQ and DMA
1511 should be numbers, or 'auto' (for using detected
1512 settings on that particular port), or 'nofifo'
1513 (to avoid using a FIFO even if it is detected).
1514 Parallel ports are assigned in the order they
1515 are specified on the command line, starting
1516 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517
Randy Dunlapa9913042005-10-23 12:57:11 -07001518 parport_init_mode= [HW,PPT]
1519 Configure VIA parallel port to operate in
1520 a specific mode. This is necessary on Pegasos
1521 computer where firmware has no options for setting
1522 up parallel port mode and sets it to spp.
1523 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 Format: [spp|ps2|epp|ecp|ecpepp]
1525
Randy Dunlapa9913042005-10-23 12:57:11 -07001526 pas2= [HW,OSS] Format:
1527 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1528
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 pas16= [HW,SCSI]
1530 See header of drivers/scsi/pas16.c.
1531
Andrew Mortondd287792006-03-23 03:00:57 -08001532 pause_on_oops=
1533 Halt all CPUs after the first oops has been printed for
1534 the specified number of seconds. This is to be used if
1535 your oopses keep scrolling off the screen.
1536
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 pcbit= [HW,ISDN]
1538
1539 pcd. [PARIDE]
1540 See header of drivers/block/paride/pcd.c.
1541 See also Documentation/paride.txt.
1542
Randy Dunlapa9913042005-10-23 12:57:11 -07001543 pci=option[,option...] [PCI] various PCI subsystem options:
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001544 off [X86-32] don't probe for the PCI bus
1545 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001546 the hardware directly. Use this if your machine
1547 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001548 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001549 hardware access methods are allowed. Use this
1550 if you experience crashes upon bootup and you
1551 suspect they are caused by the BIOS.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001552 conf1 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001553 Mechanism 1.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001554 conf2 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001555 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001556 noaer [PCIE] If the PCIEAER kernel config parameter is
1557 enabled, this kernel boot option can be used to
1558 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001559 nodomains [PCI] Disable support for multiple PCI
1560 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001561 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001562 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001563 nomsi [MSI] If the PCI_MSI kernel config parameter is
1564 enabled, this kernel boot option can be used to
1565 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001566 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001567 routing table. These calls are known to be buggy
1568 on several machines and they hang the machine
1569 when used, but on other computers it's the only
1570 way to get the interrupt routing table. Try
1571 this option if the kernel is unable to allocate
1572 IRQs or discover secondary PCI buses on your
1573 motherboard.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001574 rom [X86-32] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001575 Use with caution as certain devices share
1576 address decoders between ROMs and other
1577 resources.
Gary Hadebb71ad82008-05-12 13:57:46 -07001578 norom [X86-32,X86_64] Do not assign address space to
1579 expansion ROMs that do not already have
1580 BIOS assigned address ranges.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001581 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001582 assigned automatically to PCI devices. You can
1583 make the kernel exclude IRQs of your ISA cards
1584 this way.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001585 pirqaddr=0xAAAAA [X86-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001586 of the PIRQ table (normally generated
1587 by the BIOS) if it is outside the
1588 F0000h-100000h range.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001589 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001590 useful if the kernel is unable to find your
1591 secondary buses and you want to tell it
1592 explicitly which ones they are.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001593 assign-busses [X86-32] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001594 numbers ourselves, overriding
1595 whatever the firmware may have done.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001596 usepirqmask [X86-32] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001597 in the BIOS $PIR table. This is needed on
1598 some systems with broken BIOSes, notably
1599 some HP Pavilion N5400 and Omnibook XE3
1600 notebooks. This will have no effect if ACPI
1601 IRQ routing is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001602 noacpi [X86-32] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001603 or for PCI scanning.
Gary Hade62f420f2007-10-03 15:56:51 -07001604 use_crs [X86-32] Use _CRS for PCI resource
1605 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001606 routeirq Do IRQ routing for all PCI devices.
1607 This is normally done in pci_enable_device(),
1608 so this option is a temporary workaround
1609 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001610 skip_isa_align [X86] do not align io start addr, so can
1611 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001612 firmware [ARM] Do not re-enumerate the bus but instead
1613 just use the configuration from the
1614 bootloader. This is currently used on
1615 IXP2000 systems where the bus has to be
1616 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001617 noearly [X86] Don't do any early type 1 scanning.
1618 This might help on some broken boards which
1619 machine check when some devices' config space
1620 is read. But various workarounds are disabled
1621 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001622 bfsort Sort PCI devices into breadth-first order.
1623 This sorting is done to get a device
1624 order compatible with older (<= 2.4) kernels.
1625 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001626 cbiosize=nn[KMG] The fixed amount of bus space which is
1627 reserved for the CardBus bridge's IO window.
1628 The default value is 256 bytes.
1629 cbmemsize=nn[KMG] The fixed amount of bus space which is
1630 reserved for the CardBus bridge's memory
1631 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001632
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 pcmv= [HW,PCMCIA] BadgePAD 4
1634
1635 pd. [PARIDE]
1636 See Documentation/paride.txt.
1637
1638 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1639 boot time.
1640 Format: { 0 | 1 }
1641 See arch/parisc/kernel/pdc_chassis.c
1642
1643 pf. [PARIDE]
1644 See Documentation/paride.txt.
1645
1646 pg. [PARIDE]
1647 See Documentation/paride.txt.
1648
1649 pirq= [SMP,APIC] Manual mp-table setup
1650 See Documentation/i386/IO-APIC.txt.
1651
1652 plip= [PPT,NET] Parallel port network link
1653 Format: { parport<nr> | timid | 0 }
1654 See also Documentation/parport.txt.
1655
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001656 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1657 Override pmtimer IOPort with a hex value.
1658 e.g. pmtmr=0x508
1659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 pnpacpi= [ACPI]
1661 { off }
1662
1663 pnpbios= [ISAPNP]
1664 { on | off | curr | res | no-curr | no-res }
1665
1666 pnp_reserve_irq=
1667 [ISAPNP] Exclude IRQs for the autoconfiguration
1668
1669 pnp_reserve_dma=
1670 [ISAPNP] Exclude DMAs for the autoconfiguration
1671
1672 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001673 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674
1675 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001676 [ISAPNP] Exclude memory regions for the
1677 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 Ranges are in pairs (memory base and size).
1679
Ingo Molnar45807a12007-07-15 23:40:10 -07001680 print-fatal-signals=
1681 [KNL] debug: print fatal signals
1682 print-fatal-signals=1: print segfault info to
1683 the kernel console.
1684 default: off.
1685
Randy Dunlape84845c2007-07-15 23:40:25 -07001686 printk.time= Show timing data prefixed to each printk message line
1687 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1688
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001690 Format: [schedule,]<number>
1691 Param: "schedule" - profile schedule points.
1692 Param: <number> - step/bucket size as a power of 2 for
1693 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001694 Param: "sleep" - profile D-state sleeping (millisecs).
1695 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001696 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697
Randy Dunlapa9913042005-10-23 12:57:11 -07001698 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 Limit processor to maximum C-state
1700 max_cstate=9 overrides any DMI blacklist limit.
1701
Len Brown41c0d862005-12-28 12:43:51 -05001702 processor.nocst [HW,ACPI]
1703 Ignore the _CST method to determine C-states,
1704 instead using the legacy FADT method
1705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1707 before loading.
1708 See Documentation/ramdisk.txt.
1709
Randy Dunlapa9913042005-10-23 12:57:11 -07001710 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1711 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1713 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001714 psmouse.resetafter= [HW,MOUSE]
1715 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 (0 = never).
1717 psmouse.resolution=
1718 [HW,MOUSE] Set desired mouse resolution, in dpi.
1719 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001720 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 0 = disabled, 1 = enabled (default).
1722
1723 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001724 Format:
1725 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
1727 pt. [PARIDE]
1728 See Documentation/paride.txt.
1729
Kay Sieversdc8c8582007-08-15 12:25:38 +02001730 pty.legacy_count=
1731 [KNL] Number of legacy pty's. Overwrites compiled-in
1732 default number.
1733
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001734 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001735
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 r128= [HW,DRM]
1737
1738 raid= [HW,RAID]
1739 See Documentation/md.txt.
1740
Randy Dunlapa9913042005-10-23 12:57:11 -07001741 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 See Documentation/ramdisk.txt.
1746
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001747 rcupdate.blimit= [KNL,BOOT]
1748 Set maximum number of finished RCU callbacks to process
1749 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001750
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001751 rcupdate.qhimark= [KNL,BOOT]
1752 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001753 RCU callbacks over which batch limiting is disabled.
1754
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001755 rcupdate.qlowmark= [KNL,BOOT]
1756 Set threshold of queued RCU callbacks below which
1757 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001758
Olof Johanssonffdfc402005-09-06 15:17:19 -07001759 rdinit= [KNL]
1760 Format: <full_path>
1761 Run specified binary instead of /init from the ramdisk,
1762 used for early userspace startup. See initrd.
1763
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001764 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001766 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767
Paul Jackson46b6d942008-07-04 10:00:09 -07001768 relax_domain_level=
1769 [KNL, SMP] Set scheduler's default relax_domain_level.
1770 See Documentation/cpusets.txt.
1771
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1773
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001774 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001775 Format: nn[KMG]
1776 Reserves a hole at the top of the kernel virtual
1777 address space.
1778
Vivek Goyal7e962872006-09-27 01:50:44 -07001779 reset_devices [KNL] Force drivers to reset the underlying device
1780 during initialization.
1781
Randy Dunlapa9913042005-10-23 12:57:11 -07001782 resume= [SWSUSP]
1783 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001785 resume_offset= [SWSUSP]
1786 Specify the offset from the beginning of the partition
1787 given by "resume=" at which the swap header is located,
1788 in <PAGE_SIZE> units (needed only for swap files).
1789 See Documentation/power/swsusp-and-swap-files.txt
1790
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001791 retain_initrd [RAM] Keep initrd memory after extraction
1792
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 rhash_entries= [KNL,NET]
1794 Set number of hash buckets for route cache
1795
1796 riscom8= [HW,SERIAL]
1797 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1798
1799 ro [KNL] Mount root device read-only on boot
1800
1801 root= [KNL] Root filesystem
1802
1803 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1804 mount the root filesystem
1805
1806 rootflags= [KNL] Set root filesystem mount option string
1807
1808 rootfstype= [KNL] Set root filesystem type
1809
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001810 rootwait [KNL] Wait (indefinitely) for root device to show up.
1811 Useful for devices that are detected asynchronously
1812 (e.g. USB and MMC devices).
1813
James Morris20510f22007-10-16 23:31:32 -07001814 root_plug.vendor_id=
1815 [ROOTPLUG] Override the default vendor ID
1816
1817 root_plug.product_id=
1818 [ROOTPLUG] Override the default product ID
1819
1820 root_plug.debug=
1821 [ROOTPLUG] Enable debugging output
1822
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 rw [KNL] Mount root device read-write on boot
1824
1825 S [KNL] Run init in single mode
1826
1827 sa1100ir [NET]
1828 See drivers/net/irda/sa1100_ir.c.
1829
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001831
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1833 Format: <io>[,<timeout>[,<isapnp>]]
1834
1835 scsi_debug_*= [SCSI]
1836 See drivers/scsi/scsi_debug.c.
1837
1838 scsi_default_dev_flags=
1839 [SCSI] SCSI default device flags
1840 Format: <integer>
1841
1842 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1843 Format: <vendor>:<model>:<flags>
1844 (flags are integer value)
1845
Randy Dunlap6af66322007-11-14 16:52:25 -08001846 scsi_logging_level= [SCSI] a bit mask of logging levels
1847 See drivers/scsi/scsi_logging.h for bits. Also
1848 settable via sysctl at dev.scsi.logging_level
1849 (/proc/sys/dev/scsi/logging_level).
1850 There is also a nice 'scsi_logging_level' script in the
1851 S390-tools package, available for download at
1852 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001854 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1855 discovered. async scans them in kernel threads,
1856 allowing boot to proceed. none ignores them, expecting
1857 user space to do the scan.
1858
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 selinux [SELINUX] Disable or enable SELinux at boot time.
1860 Format: { "0" | "1" }
1861 See security/selinux/Kconfig help text.
1862 0 -- disable.
1863 1 -- enable.
1864 Default value is set via kernel config option.
1865 If enabled at boot time, /selinux/disable can be used
1866 later to disable prior to initial policy load.
1867
James Morris4e5ab4c2006-06-09 00:33:33 -07001868 selinux_compat_net =
1869 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001870 Format: { "0" | "1" }
1871 0 -- use new secmark-based packet controls
1872 1 -- use legacy packet controls
1873 Default value is 0 (preferred).
1874 Value can be changed at runtime via
1875 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001876
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001877 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879 shapers= [NET]
1880 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001881
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 sim710= [SCSI,HW]
1883 See header of drivers/scsi/sim710.c.
1884
1885 simeth= [IA-64]
1886 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001887
Linus Torvalds1da177e2005-04-16 15:20:36 -07001888 slram= [HW,MTD]
1889
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001890 slub_debug[=options[,slabs]] [MM, SLUB]
1891 Enabling slub_debug allows one to determine the
1892 culprit if slab objects become corrupted. Enabling
1893 slub_debug can create guard zones around objects and
1894 may poison objects when not in use. Also tracks the
1895 last alloc / free. For more information see
1896 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001897
1898 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001899 Determines the maximum allowed order for slabs.
1900 A high setting may cause OOMs due to memory
1901 fragmentation. For more information see
1902 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001903
1904 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001905 The minimum number of objects per slab. SLUB will
1906 increase the slab order up to slub_max_order to
1907 generate a sufficiently large slab able to contain
1908 the number of objects indicated. The higher the number
1909 of objects the smaller the overhead of tracking slabs
1910 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001911 For more information see Documentation/vm/slub.txt.
1912
1913 slub_min_order= [MM, SLUB]
1914 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001915 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001916 For more information see Documentation/vm/slub.txt.
1917
1918 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001919 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07001920 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001921 allocs to different slabs. Debug options disable
1922 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001923 For more information see Documentation/vm/slub.txt.
1924
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 smart2= [HW]
1926 Format: <io1>[,<io2>[,...,<io8>]]
1927
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001928 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001929 attempt to substitute SMP alternatives once at boot.
1930
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001931 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1932 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1933 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1934 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1935 smsc-ircc2.ircc_irq= [HW] IRQ line
1936 smsc-ircc2.ircc_dma= [HW] DMA channel
1937 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1938 0: Toshiba Satellite 1800 (GP data pin select)
1939 1: Fast pin select (default)
1940 2: ATC IRMode
1941
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942 snd-ad1816a= [HW,ALSA]
1943
1944 snd-ad1848= [HW,ALSA]
1945
1946 snd-ali5451= [HW,ALSA]
1947
1948 snd-als100= [HW,ALSA]
1949
1950 snd-als4000= [HW,ALSA]
1951
1952 snd-azt2320= [HW,ALSA]
1953
1954 snd-cmi8330= [HW,ALSA]
1955
1956 snd-cmipci= [HW,ALSA]
1957
1958 snd-cs4231= [HW,ALSA]
1959
1960 snd-cs4232= [HW,ALSA]
1961
1962 snd-cs4236= [HW,ALSA]
1963
1964 snd-cs4281= [HW,ALSA]
1965
1966 snd-cs46xx= [HW,ALSA]
1967
1968 snd-dt019x= [HW,ALSA]
1969
1970 snd-dummy= [HW,ALSA]
1971
1972 snd-emu10k1= [HW,ALSA]
1973
1974 snd-ens1370= [HW,ALSA]
1975
1976 snd-ens1371= [HW,ALSA]
1977
1978 snd-es968= [HW,ALSA]
1979
1980 snd-es1688= [HW,ALSA]
1981
1982 snd-es18xx= [HW,ALSA]
1983
1984 snd-es1938= [HW,ALSA]
1985
1986 snd-es1968= [HW,ALSA]
1987
1988 snd-fm801= [HW,ALSA]
1989
1990 snd-gusclassic= [HW,ALSA]
1991
1992 snd-gusextreme= [HW,ALSA]
1993
1994 snd-gusmax= [HW,ALSA]
1995
1996 snd-hdsp= [HW,ALSA]
1997
1998 snd-ice1712= [HW,ALSA]
1999
2000 snd-intel8x0= [HW,ALSA]
2001
2002 snd-interwave= [HW,ALSA]
2003
2004 snd-interwave-stb=
2005 [HW,ALSA]
2006
2007 snd-korg1212= [HW,ALSA]
2008
2009 snd-maestro3= [HW,ALSA]
2010
2011 snd-mpu401= [HW,ALSA]
2012
2013 snd-mtpav= [HW,ALSA]
2014
2015 snd-nm256= [HW,ALSA]
2016
2017 snd-opl3sa2= [HW,ALSA]
2018
2019 snd-opti92x-ad1848=
2020 [HW,ALSA]
2021
2022 snd-opti92x-cs4231=
2023 [HW,ALSA]
2024
2025 snd-opti93x= [HW,ALSA]
2026
2027 snd-pmac= [HW,ALSA]
2028
2029 snd-rme32= [HW,ALSA]
2030
2031 snd-rme96= [HW,ALSA]
2032
2033 snd-rme9652= [HW,ALSA]
2034
2035 snd-sb8= [HW,ALSA]
2036
2037 snd-sb16= [HW,ALSA]
2038
2039 snd-sbawe= [HW,ALSA]
2040
2041 snd-serial= [HW,ALSA]
2042
2043 snd-sgalaxy= [HW,ALSA]
2044
2045 snd-sonicvibes= [HW,ALSA]
2046
2047 snd-sun-amd7930=
2048 [HW,ALSA]
2049
2050 snd-sun-cs4231= [HW,ALSA]
2051
2052 snd-trident= [HW,ALSA]
2053
2054 snd-usb-audio= [HW,ALSA,USB]
2055
2056 snd-via82xx= [HW,ALSA]
2057
2058 snd-virmidi= [HW,ALSA]
2059
2060 snd-wavefront= [HW,ALSA]
2061
2062 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002063
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002064 softlockup_panic=
2065 [KNL] Should the soft-lockup detector generate panics.
2066
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2068 See Documentation/sonypi.txt
2069
2070 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2071 See Documentation/specialix.txt.
2072
2073 spia_io_base= [HW,MTD]
2074 spia_fio_base=
2075 spia_pedr=
2076 spia_peddr=
2077
2078 sscape= [HW,OSS]
2079 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002080
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2082 See Documentation/scsi/st.txt.
2083
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084 sti= [PARISC,HW]
2085 Format: <num>
2086 Set the STI (builtin display/keyboard on the HP-PARISC
2087 machines) console (graphic card) which should be used
2088 as the initial boot-console.
2089 See also comment in drivers/video/console/sticore.c.
2090
2091 sti_font= [HW]
2092 See comment in drivers/video/console/sticore.c.
2093
2094 stifb= [HW]
2095 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2096
Greg Banks42a7fc42007-03-06 01:42:23 -08002097 sunrpc.pool_mode=
2098 [NFS]
2099 Control how the NFS server code allocates CPUs to
2100 service thread pools. Depending on how many NICs
2101 you have and where their interrupts are bound, this
2102 option will affect which CPUs will do NFS serving.
2103 Note: this parameter cannot be changed while the
2104 NFS server is running.
2105
2106 auto the server chooses an appropriate mode
2107 automatically using heuristics
2108 global a single global pool contains all CPUs
2109 percpu one pool for each CPU
2110 pernode one pool for each NUMA node (equivalent
2111 to global on non-NUMA machines)
2112
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002114
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 switches= [HW,M68k]
2116
2117 sym53c416= [HW,SCSI]
2118 See header of drivers/scsi/sym53c416.c.
2119
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002120 sysrq_always_enabled
2121 [KNL]
2122 Ignore sysrq setting - this boot parameter will
2123 neutralize any effect of /proc/sys/kernel/sysrq.
2124 Useful for debugging.
2125
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126 t128= [HW,SCSI]
2127 See header of drivers/scsi/t128.c.
2128
2129 tdfx= [HW,DRM]
2130
David Brownell77437fd2008-07-23 21:28:33 -07002131 test_suspend= [SUSPEND]
2132 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2133 standby suspend) as the system sleep state to briefly
2134 enter during system startup. The system is woken from
2135 this state using a wakeup-capable RTC alarm.
2136
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 thash_entries= [KNL,NET]
2138 Set number of hash buckets for TCP connection
2139
Len Brownf8707ec2007-08-12 00:12:54 -04002140 thermal.act= [HW,ACPI]
2141 -1: disable all active trip points in all thermal zones
2142 <degrees C>: override all lowest active trip points
2143
Len Brownc52a7412007-08-14 15:49:32 -04002144 thermal.crt= [HW,ACPI]
2145 -1: disable all critical trip points in all thermal zones
2146 <degrees C>: lower all critical trip points
2147
Len Brownf5487142007-08-12 00:12:44 -04002148 thermal.nocrt= [HW,ACPI]
2149 Set to disable actions on ACPI thermal zone
2150 critical and hot trip points.
2151
Len Brown72b33ef2007-08-12 00:12:17 -04002152 thermal.off= [HW,ACPI]
2153 1: disable ACPI thermal control
2154
Len Browna70cdc52007-08-12 00:12:35 -04002155 thermal.psv= [HW,ACPI]
2156 -1: disable all passive trip points
2157 <degrees C>: override all passive trip points to this value
2158
Len Brown730ff342007-08-12 00:12:26 -04002159 thermal.tzp= [HW,ACPI]
2160 Specify global default ACPI thermal zone polling rate
2161 <deci-seconds>: poll all this frequency
2162 0: no polling (default)
2163
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 tmscsim= [HW,SCSI]
2165 See comment before function dc390_setup() in
2166 drivers/scsi/tmscsim.c.
2167
2168 tp720= [HW,PS2]
2169
2170 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002171 Format:
2172 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2173
Randy Dunlapa9913042005-10-23 12:57:11 -07002174 turbografx.map[2|3]= [HW,JOY]
2175 TurboGraFX parallel port interface
2176 Format:
2177 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178 See also Documentation/input/joystick-parport.txt
2179
2180 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2181 See header of drivers/scsi/u14-34f.c.
2182
2183 uart401= [HW,OSS]
2184 Format: <io>,<irq>
2185
2186 uart6850= [HW,OSS]
2187 Format: <io>,<irq>
2188
Alan Stern5f8364b2006-12-05 16:29:55 -05002189 uhci-hcd.ignore_oc=
2190 [USB] Ignore overcurrent events (default N).
2191 Some badly-designed motherboards generate lots of
2192 bogus events, for ports that aren't wired to
2193 anything. Set this parameter to avoid log spamming.
2194 Note that genuine overcurrent events won't be
2195 reported either.
2196
Simon Arlotte3a61b02008-07-19 23:32:54 +01002197 unknown_nmi_panic
2198 [X86-32,X86-64]
2199 Set unknown_nmi_panic=1 early on boot.
2200
Alan Sternb5e795f2007-02-20 15:00:53 -05002201 usbcore.autosuspend=
2202 [USB] The autosuspend time delay (in seconds) used
2203 for newly-detected USB devices (default 2). This
2204 is the time required before an idle device will be
2205 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002206 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002207
Linus Torvalds1da177e2005-04-16 15:20:36 -07002208 usbhid.mousepoll=
2209 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002210
Paul Jackson200001e2008-06-25 05:44:46 -07002211 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2212 kernel's map of available physical RAM.
2213
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002214 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002215 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002216 vdso=1: enable VDSO (default)
2217 vdso=0: disable VDSO mapping
2218
Roland McGrathaf65d642008-01-30 13:30:43 +01002219 vdso32= [X86-32,X86-64]
2220 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2221 vdso32=1: enable 32-bit VDSO (default)
2222 vdso32=0: disable 32-bit VDSO mapping
2223
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002224 vector= [IA-64,SMP]
2225 vector=percpu: enable percpu vector domain
2226
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 video= [FB] Frame buffer configuration
2228 See Documentation/fb/modedb.txt.
2229
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002230 vga= [BOOT,X86-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07002231 See Documentation/i386/boot.txt and
2232 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002233 Use vga=ask for menu.
2234 This is actually a boot loader parameter; the value is
2235 passed to the kernel using a special protocol.
2236
Randy Dunlapa9913042005-10-23 12:57:11 -07002237 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 size of <nn>. This can be used to increase the
2239 minimum size (128MB on x86). It can also be used to
2240 decrease the size and leave more room for directly
2241 mapped kernel RAM.
2242
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002243 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2244 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002246 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2247 Format: <command>
2248
2249 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2250 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002251
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 waveartist= [HW,OSS]
2253 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002254
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 wd33c93= [HW,SCSI]
2256 See header of drivers/scsi/wd33c93.c.
2257
2258 wd7000= [HW,SCSI]
2259 See header of drivers/scsi/wd7000.c.
2260
2261 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002262 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263
2264 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2265 xd_geo= See header of drivers/block/xd.c.
2266
2267 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002268 Format:
2269 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270
Andi Kleena62eaf12006-02-16 23:41:58 +01002271 norandmaps Don't use address space randomization
2272 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2273
Randy Dunlapa9913042005-10-23 12:57:11 -07002274______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002275
2276TODO:
2277
2278 Add documentation for ALSA options.
2279 Add more DRM drivers.