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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 Gorman7e63efef2007-07-17 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
Tejun Heo05944bd2008-08-13 20:19:09 +09001077 * nohrst, nosrst, norst: suppress hard, soft
1078 and both resets.
1079
Tejun Heo33267322008-02-13 09:15:09 +09001080 If there are multiple matching configurations changing
1081 the same attribute, the last one is used.
1082
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 load_ramdisk= [RAM] List of ramdisks to load from floppy
1084 See Documentation/ramdisk.txt.
1085
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001086 lockd.nlm_grace_period=P [NFS] Assign grace period.
1087 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001089 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1090 Format: <integer>
1091
1092 lockd.nlm_timeout=T [NFS] Assign timeout value.
1093 Format: <integer>
1094
1095 lockd.nlm_udpport=M [NFS] Assign UDP port.
1096 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097
1098 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1099 Format: <irq>
1100
1101 loglevel= All Kernel Messages with a loglevel smaller than the
1102 console loglevel will be printed to the console. It can
1103 also be changed with klogd or other programs. The
1104 loglevels are defined as follows:
1105
1106 0 (KERN_EMERG) system is unusable
1107 1 (KERN_ALERT) action must be taken immediately
1108 2 (KERN_CRIT) critical conditions
1109 3 (KERN_ERR) error conditions
1110 4 (KERN_WARNING) warning conditions
1111 5 (KERN_NOTICE) normal but significant condition
1112 6 (KERN_INFO) informational
1113 7 (KERN_DEBUG) debug-level messages
1114
1115 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001116 Format: { n | nk | nM }
1117 n must be a power of two. The default size
1118 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119
Randy Dunlapaccaa242007-10-16 01:29:37 -07001120 logo.nologo [FB] Disables display of the built-in Linux logo.
1121 This may be used to provide more screen space for
1122 kernel log messages and is useful when debugging
1123 kernel boot problems.
1124
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 lp=0 [LP] Specify parallel ports to use, e.g,
1126 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1127 lp=reset first parallel port). 'lp=0' disables the
1128 lp=auto printer driver. 'lp=reset' (which can be
1129 specified in addition to the ports) causes
1130 attached printers to be reset. Using
1131 lp=port1,port2,... specifies the parallel ports
1132 to associate lp devices with, starting with
1133 lp0. A port specification may be 'none' to skip
1134 that lp device, or a parport name such as
1135 'parport0'. Specifying 'lp=auto' instead of a
1136 port specification list means that device IDs
1137 from each port should be examined, to see if
1138 an IEEE 1284-compliant printer is attached; if
1139 so, the driver will manage that printer.
1140 See also header of drivers/char/lp.c.
1141
1142 lpj=n [KNL]
1143 Sets loops_per_jiffy to given constant, thus avoiding
1144 time-consuming boot-time autodetection (up to 250 ms per
1145 CPU). 0 enables autodetection (default). To determine
1146 the correct value for your kernel, boot with normal
1147 autodetection and see what value is printed. Note that
1148 on SMP systems the preset will be applied to all CPUs,
1149 which is likely to cause problems if your CPUs need
1150 significantly divergent settings. An incorrect value
1151 will cause delays in the kernel to be wrong, leading to
1152 unpredictable I/O errors and other breakage. Although
1153 unlikely, in the extreme case this might damage your
1154 hardware.
1155
1156 ltpc= [NET]
1157 Format: <io>,<irq>,<dma>
1158
Randy Dunlapa9913042005-10-23 12:57:11 -07001159 mac5380= [HW,SCSI] Format:
1160 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161
Randy Dunlapa9913042005-10-23 12:57:11 -07001162 machvec= [IA64] Force the use of a particular machine-vector
1163 (machvec) in a generic kernel.
1164 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165
Randy Dunlapa9913042005-10-23 12:57:11 -07001166 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167 be mounted
1168 Format: <1-256>
1169
1170 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001171 should make use of. maxcpus=n : n >= 0 limits the
1172 kernel to using 'n' processors. n=0 is a special case,
1173 it is equivalent to "nosmp", which also disables
1174 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
Bob Picco2b2c3752005-06-29 18:00:00 -07001176 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1177 equal to this physical address is ignored.
1178
Randy Dunlapa9913042005-10-23 12:57:11 -07001179 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 Should be between 1 and 2^32-1.
1181
1182 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001183 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 Should be between 1 and 16384.
1185
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 mcatest= [IA-64]
1187
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001188 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
Andi Kleen909dd322007-10-17 18:04:38 +02001190 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1191
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 md= [HW] RAID subsystems devices and level
1193 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001194
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 mdacon= [MDA]
1196 Format: <first>,<last>
1197 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001198
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1200 Amount of memory to be used when the kernel is not able
1201 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001202 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203 address space collisions. Without memmap= PCI devices
1204 could be placed at addresses belonging to unused RAM.
1205
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001206 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 memory.
1208
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001209 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 E820 memory map, as specified by the user.
1211 Such memmap=exactmap lines can be constructed based on
1212 BIOS output or other requirements. See the memmap=nn@ss
1213 option description.
1214
1215 memmap=nn[KMG]@ss[KMG]
1216 [KNL] Force usage of a specific region of memory
1217 Region of memory to be used, from ss to ss+nn.
1218
1219 memmap=nn[KMG]#ss[KMG]
1220 [KNL,ACPI] Mark specific memory as ACPI data.
1221 Region of memory to be used, from ss to ss+nn.
1222
1223 memmap=nn[KMG]$ss[KMG]
1224 [KNL,ACPI] Mark specific memory as reserved.
1225 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001226 Example: Exclude memory from 0x18690000-0x1869ffff
1227 memmap=64K$0x18690000
1228 or
1229 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001231 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001232 Format: <integer>
1233 range: 0,4 : pattern number
1234 default : 0 <disable>
1235
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 meye.*= [HW] Set MotionEye Camera parameters
1237 See Documentation/video4linux/meye.txt.
1238
Andres Salomon8f368812007-10-12 23:04:06 +02001239 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1240 Multi-Function General Purpose Timers on AMD Geode
1241 platforms.
1242
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001243 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1244 the BIOS has incorrectly applied a workaround. TinyBIOS
1245 version 0.98 is known to be affected, 0.99 fixes the
1246 problem by letting the user disable the workaround.
1247
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 mga= [HW,DRM]
1249
Mel Gorman6b74ab92008-07-23 21:26:49 -07001250 mminit_loglevel=
1251 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1252 parameter allows control of the logging verbosity for
1253 the additional memory initialisation checks. A value
1254 of 0 disables mminit logging and a level of 4 will
1255 log everything. Information is printed at KERN_DEBUG
1256 so loglevel=8 may also need to be specified.
1257
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 mousedev.tap_time=
1259 [MOUSE] Maximum time between finger touching and
1260 leaving touchpad surface for touch to be considered
1261 a tap and be reported as a left button click (for
1262 touchpads working in absolute mode only).
1263 Format: <msecs>
1264 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1265 reporting absolute coordinates, such as tablets
1266 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1267 reporting absolute coordinates, such as tablets
1268
1269 mpu401= [HW,OSS]
1270 Format: <io>,<irq>
1271
1272 MTD_Partition= [MTD]
1273 Format: <name>,<region-number>,<size>,<offset>
1274
Randy Dunlapa9913042005-10-23 12:57:11 -07001275 MTD_Region= [MTD] Format:
1276 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277
1278 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001279 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
Ben Dooks9db829f2008-07-03 11:24:29 +01001281 mtdset= [ARM]
1282 ARM/S3C2412 JIVE boot control
1283
1284 See arch/arm/mach-s3c2412/mach-jive.c
1285
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001287 [HW] Make the MicroTouch USB driver use raw coordinates
1288 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
1290 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1291
1292 NCR_D700= [HW,SCSI]
1293 See header of drivers/scsi/NCR_D700.c.
1294
1295 ncr5380= [HW,SCSI]
1296
1297 ncr53c400= [HW,SCSI]
1298
1299 ncr53c400a= [HW,SCSI]
1300
1301 ncr53c406a= [HW,SCSI]
1302
1303 ncr53c8xx= [HW,SCSI]
1304
1305 netdev= [NET] Network devices parameters
1306 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1307 Note that mem_start is often overloaded to mean
1308 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001309 This usage is only documented in each driver source
1310 file if at all.
1311
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001312 nf_conntrack.acct=
1313 [NETFILTER] Enable connection tracking flow accounting
1314 0 to disable accounting
1315 1 to enable accounting
1316 Default value depends on CONFIG_NF_CT_ACCT that is
1317 going to be removed in 2.6.29.
1318
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001320 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321
1322 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001323 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324
Trond Myklebusta72b4422006-01-03 09:55:41 +01001325 nfs.callback_tcpport=
1326 [NFS] set the TCP port on which the NFSv4 callback
1327 channel should listen.
1328
Trond Myklebust58df0952006-01-03 09:55:57 +01001329 nfs.idmap_cache_timeout=
1330 [NFS] set the maximum lifetime for idmapper cache
1331 entries.
1332
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001333 nfs.enable_ino64=
1334 [NFS] enable 64-bit inode numbers.
1335 If zero, the NFS client will fake up a 32-bit inode
1336 number for the readdir() and stat() syscalls instead
1337 of returning the full 64-bit number.
1338 The default is to return 64-bit inode numbers.
1339
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001340 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1341 when a NMI is triggered.
1342 Format: [state][,regs][,debounce][,die]
1343
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001344 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001346 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 emulation library even if a 387 maths coprocessor
1348 is present.
1349
Christoph Lameterc1aee212007-05-31 00:40:47 -07001350 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1351 caches in the slab allocator. Saves per-node memory,
1352 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001353
Randy Dunlapa9913042005-10-23 12:57:11 -07001354 noalign [KNL,ARM]
1355
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 noapic [SMP,APIC] Tells the kernel to not make use of any
1357 IOAPICs that may be present in the system.
1358
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 nobats [PPC] Do not use BATs for mapping kernel lowmem
1360 on "Classic" PPC cores.
1361
1362 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001363
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001364 nodelayacct [KNL] Disable per-task delay accounting
1365
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1367
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001368 noefi [X86-32,X86-64] Disable EFI runtime services support.
1369
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 noexec [IA-64]
1371
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001372 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001373 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001375 noexec=off: disable non-executable mappings
1376
1377 noexec32 [X86-64]
1378 This affects only 32-bit executables.
1379 noexec32=on: enable non-executable mappings (default)
1380 read doesn't imply executable mappings
1381 noexec32=off: disable non-executable mappings
1382 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001384 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001385 register save and restore. The kernel will only save
1386 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387
Andi Kleen191679f2008-01-30 13:33:21 +01001388 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001391
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001392 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 instruction doesn't work correctly and not to
1394 use it.
1395
1396 nohalt [IA-64] Tells the kernel not to use the power saving
1397 function PAL_HALT_LIGHT when idle. This increases
1398 power-consumption. On the positive side, it reduces
1399 interrupt wake-up latency, which may improve performance
1400 in certain environments such as networked servers or
1401 real-time systems.
1402
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001403 nohz= [KNL] Boottime enable/disable dynamic ticks
1404 Valid arguments: on, off
1405 Default: on
1406
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001407 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
Zachary Amsden8542b202006-12-07 02:14:09 +01001408
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001409 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 disable unhandled interrupt sources.
1411
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001412 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001413 broken timer IRQ sources.
1414
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 noisapnp [ISAPNP] Disables ISA PnP code.
1416
1417 noinitrd [RAM] Tells the kernel not to load any configured
1418 initial RAM disk.
1419
1420 nointroute [IA-64]
1421
Tony Luck0aa366f2007-07-20 11:22:30 -07001422 nojitter [IA64] Disables jitter checking for ITC timers.
1423
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001424 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001426 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001427
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 noltlbs [PPC] Do not use large page/tlb entries for kernel
1429 lowmem mapping on PPC40x.
1430
Horms312f1f02006-02-22 09:57:55 +09001431 nomca [IA-64] Disable machine check abort handling
1432
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001433 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001434
Andres Salomon83d73842007-10-12 23:04:06 +02001435 nomfgpt [X86-32] Disable Multi-Function General Purpose
1436 Timer usage (for AMD Geode machines).
1437
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001438 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001439
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001440 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001441 with UP alternatives
1442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 noresidual [PPC] Don't use residual data on PReP machines.
1444
Randy Dunlapa9913042005-10-23 12:57:11 -07001445 noresume [SWSUSP] Disables resume and restores original swap
1446 space.
1447
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 no-scroll [VGA] Disables scrollback.
1449 This is required for the Braillex ib80-piezo Braille
1450 reader made by F.H. Papenmeier (Germany).
1451
1452 nosbagart [IA-64]
1453
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001454 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001455
Len Brown61ec7562007-08-16 03:34:22 -04001456 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1457 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458
Dave Jones97842212007-07-15 23:41:05 -07001459 nosoftlockup [KNL] Disable the soft-lockup detector.
1460
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461 nosync [HW,M68K] Disables sync negotiation for all devices.
1462
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001463 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464
1465 nousb [USB] Disable the USB subsystem
1466
1467 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001468
Fenghua Yua6c75b862008-03-14 13:57:08 -07001469 nptcg= [IA64] Override max number of concurrent global TLB
1470 purges which is reported from either PAL_VM_SUMMARY or
1471 SAL PALO.
1472
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001473 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1474 one of ['zone', 'node', 'default'] can be specified
1475 This can be set from sysctl after boot.
1476 See Documentation/sysctl/vm.txt for details.
1477
Dave Jonesa61c2d72006-01-07 23:18:19 +00001478 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1479
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001480 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1481 Rather than timing out after 20 ms if an EC
1482 command is not properly ACKed, override the length
1483 of the timeout. We have interrupts disabled while
1484 waiting for the ACK, so if this is set too high
1485 interrupts *may* be lost!
1486
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 opl3= [HW,OSS]
1488 Format: <io>
1489
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 oprofile.timer= [HW]
1491 Use timer interrupt instead of performance counters
1492
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 osst= [HW,SCSI] SCSI Tape Driver
1494 Format: <buffer_size>,<write_threshold>
1495 See also Documentation/scsi/st.txt.
1496
1497 panic= [KNL] Kernel behaviour on panic
1498 Format: <timeout>
1499
1500 parkbd.port= [HW] Parallel port number the keyboard adapter is
1501 connected to, default is 0.
1502 Format: <parport#>
1503 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1504 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001505 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506
Randy Dunlapa9913042005-10-23 12:57:11 -07001507 parport= [HW,PPT] Specify parallel ports. 0 disables.
1508 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1509 Use 'auto' to force the driver to use any
1510 IRQ/DMA settings detected (the default is to
1511 ignore detected IRQ/DMA settings because of
1512 possible conflicts). You can specify the base
1513 address, IRQ, and DMA settings; IRQ and DMA
1514 should be numbers, or 'auto' (for using detected
1515 settings on that particular port), or 'nofifo'
1516 (to avoid using a FIFO even if it is detected).
1517 Parallel ports are assigned in the order they
1518 are specified on the command line, starting
1519 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520
Randy Dunlapa9913042005-10-23 12:57:11 -07001521 parport_init_mode= [HW,PPT]
1522 Configure VIA parallel port to operate in
1523 a specific mode. This is necessary on Pegasos
1524 computer where firmware has no options for setting
1525 up parallel port mode and sets it to spp.
1526 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 Format: [spp|ps2|epp|ecp|ecpepp]
1528
Randy Dunlapa9913042005-10-23 12:57:11 -07001529 pas2= [HW,OSS] Format:
1530 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1531
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532 pas16= [HW,SCSI]
1533 See header of drivers/scsi/pas16.c.
1534
Andrew Mortondd287792006-03-23 03:00:57 -08001535 pause_on_oops=
1536 Halt all CPUs after the first oops has been printed for
1537 the specified number of seconds. This is to be used if
1538 your oopses keep scrolling off the screen.
1539
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 pcbit= [HW,ISDN]
1541
1542 pcd. [PARIDE]
1543 See header of drivers/block/paride/pcd.c.
1544 See also Documentation/paride.txt.
1545
Randy Dunlapa9913042005-10-23 12:57:11 -07001546 pci=option[,option...] [PCI] various PCI subsystem options:
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001547 off [X86-32] don't probe for the PCI bus
1548 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001549 the hardware directly. Use this if your machine
1550 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001551 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001552 hardware access methods are allowed. Use this
1553 if you experience crashes upon bootup and you
1554 suspect they are caused by the BIOS.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001555 conf1 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001556 Mechanism 1.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001557 conf2 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001558 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001559 noaer [PCIE] If the PCIEAER kernel config parameter is
1560 enabled, this kernel boot option can be used to
1561 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001562 nodomains [PCI] Disable support for multiple PCI
1563 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001564 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001565 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001566 nomsi [MSI] If the PCI_MSI kernel config parameter is
1567 enabled, this kernel boot option can be used to
1568 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001569 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001570 routing table. These calls are known to be buggy
1571 on several machines and they hang the machine
1572 when used, but on other computers it's the only
1573 way to get the interrupt routing table. Try
1574 this option if the kernel is unable to allocate
1575 IRQs or discover secondary PCI buses on your
1576 motherboard.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001577 rom [X86-32] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001578 Use with caution as certain devices share
1579 address decoders between ROMs and other
1580 resources.
Gary Hadebb71ad82008-05-12 13:57:46 -07001581 norom [X86-32,X86_64] Do not assign address space to
1582 expansion ROMs that do not already have
1583 BIOS assigned address ranges.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001584 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001585 assigned automatically to PCI devices. You can
1586 make the kernel exclude IRQs of your ISA cards
1587 this way.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001588 pirqaddr=0xAAAAA [X86-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001589 of the PIRQ table (normally generated
1590 by the BIOS) if it is outside the
1591 F0000h-100000h range.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001592 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001593 useful if the kernel is unable to find your
1594 secondary buses and you want to tell it
1595 explicitly which ones they are.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001596 assign-busses [X86-32] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001597 numbers ourselves, overriding
1598 whatever the firmware may have done.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001599 usepirqmask [X86-32] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001600 in the BIOS $PIR table. This is needed on
1601 some systems with broken BIOSes, notably
1602 some HP Pavilion N5400 and Omnibook XE3
1603 notebooks. This will have no effect if ACPI
1604 IRQ routing is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001605 noacpi [X86-32] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001606 or for PCI scanning.
Gary Hade62f420f2007-10-03 15:56:51 -07001607 use_crs [X86-32] Use _CRS for PCI resource
1608 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001609 routeirq Do IRQ routing for all PCI devices.
1610 This is normally done in pci_enable_device(),
1611 so this option is a temporary workaround
1612 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001613 skip_isa_align [X86] do not align io start addr, so can
1614 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001615 firmware [ARM] Do not re-enumerate the bus but instead
1616 just use the configuration from the
1617 bootloader. This is currently used on
1618 IXP2000 systems where the bus has to be
1619 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001620 noearly [X86] Don't do any early type 1 scanning.
1621 This might help on some broken boards which
1622 machine check when some devices' config space
1623 is read. But various workarounds are disabled
1624 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001625 bfsort Sort PCI devices into breadth-first order.
1626 This sorting is done to get a device
1627 order compatible with older (<= 2.4) kernels.
1628 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001629 cbiosize=nn[KMG] The fixed amount of bus space which is
1630 reserved for the CardBus bridge's IO window.
1631 The default value is 256 bytes.
1632 cbmemsize=nn[KMG] The fixed amount of bus space which is
1633 reserved for the CardBus bridge's memory
1634 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001635
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636 pcmv= [HW,PCMCIA] BadgePAD 4
1637
1638 pd. [PARIDE]
1639 See Documentation/paride.txt.
1640
1641 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1642 boot time.
1643 Format: { 0 | 1 }
1644 See arch/parisc/kernel/pdc_chassis.c
1645
1646 pf. [PARIDE]
1647 See Documentation/paride.txt.
1648
1649 pg. [PARIDE]
1650 See Documentation/paride.txt.
1651
1652 pirq= [SMP,APIC] Manual mp-table setup
1653 See Documentation/i386/IO-APIC.txt.
1654
1655 plip= [PPT,NET] Parallel port network link
1656 Format: { parport<nr> | timid | 0 }
1657 See also Documentation/parport.txt.
1658
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001659 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1660 Override pmtimer IOPort with a hex value.
1661 e.g. pmtmr=0x508
1662
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 pnpacpi= [ACPI]
1664 { off }
1665
1666 pnpbios= [ISAPNP]
1667 { on | off | curr | res | no-curr | no-res }
1668
1669 pnp_reserve_irq=
1670 [ISAPNP] Exclude IRQs for the autoconfiguration
1671
1672 pnp_reserve_dma=
1673 [ISAPNP] Exclude DMAs for the autoconfiguration
1674
1675 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001676 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677
1678 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001679 [ISAPNP] Exclude memory regions for the
1680 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 Ranges are in pairs (memory base and size).
1682
Ingo Molnar45807a12007-07-15 23:40:10 -07001683 print-fatal-signals=
1684 [KNL] debug: print fatal signals
1685 print-fatal-signals=1: print segfault info to
1686 the kernel console.
1687 default: off.
1688
Randy Dunlape84845c2007-07-15 23:40:25 -07001689 printk.time= Show timing data prefixed to each printk message line
1690 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1691
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001693 Format: [schedule,]<number>
1694 Param: "schedule" - profile schedule points.
1695 Param: <number> - step/bucket size as a power of 2 for
1696 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001697 Param: "sleep" - profile D-state sleeping (millisecs).
1698 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001699 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700
Randy Dunlapa9913042005-10-23 12:57:11 -07001701 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 Limit processor to maximum C-state
1703 max_cstate=9 overrides any DMI blacklist limit.
1704
Len Brown41c0d862005-12-28 12:43:51 -05001705 processor.nocst [HW,ACPI]
1706 Ignore the _CST method to determine C-states,
1707 instead using the legacy FADT method
1708
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1710 before loading.
1711 See Documentation/ramdisk.txt.
1712
Randy Dunlapa9913042005-10-23 12:57:11 -07001713 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1714 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1716 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001717 psmouse.resetafter= [HW,MOUSE]
1718 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 (0 = never).
1720 psmouse.resolution=
1721 [HW,MOUSE] Set desired mouse resolution, in dpi.
1722 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001723 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724 0 = disabled, 1 = enabled (default).
1725
1726 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001727 Format:
1728 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
1730 pt. [PARIDE]
1731 See Documentation/paride.txt.
1732
Kay Sieversdc8c8582007-08-15 12:25:38 +02001733 pty.legacy_count=
1734 [KNL] Number of legacy pty's. Overwrites compiled-in
1735 default number.
1736
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001737 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001738
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 r128= [HW,DRM]
1740
1741 raid= [HW,RAID]
1742 See Documentation/md.txt.
1743
Randy Dunlapa9913042005-10-23 12:57:11 -07001744 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001746
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 See Documentation/ramdisk.txt.
1749
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001750 rcupdate.blimit= [KNL,BOOT]
1751 Set maximum number of finished RCU callbacks to process
1752 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001753
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001754 rcupdate.qhimark= [KNL,BOOT]
1755 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001756 RCU callbacks over which batch limiting is disabled.
1757
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001758 rcupdate.qlowmark= [KNL,BOOT]
1759 Set threshold of queued RCU callbacks below which
1760 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001761
Olof Johanssonffdfc402005-09-06 15:17:19 -07001762 rdinit= [KNL]
1763 Format: <full_path>
1764 Run specified binary instead of /init from the ramdisk,
1765 used for early userspace startup. See initrd.
1766
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001767 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001769 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770
Paul Jackson46b6d942008-07-04 10:00:09 -07001771 relax_domain_level=
1772 [KNL, SMP] Set scheduler's default relax_domain_level.
1773 See Documentation/cpusets.txt.
1774
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1776
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001777 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07001778 Format: nn[KMG]
1779 Reserves a hole at the top of the kernel virtual
1780 address space.
1781
Vivek Goyal7e962872006-09-27 01:50:44 -07001782 reset_devices [KNL] Force drivers to reset the underlying device
1783 during initialization.
1784
Randy Dunlapa9913042005-10-23 12:57:11 -07001785 resume= [SWSUSP]
1786 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001788 resume_offset= [SWSUSP]
1789 Specify the offset from the beginning of the partition
1790 given by "resume=" at which the swap header is located,
1791 in <PAGE_SIZE> units (needed only for swap files).
1792 See Documentation/power/swsusp-and-swap-files.txt
1793
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001794 retain_initrd [RAM] Keep initrd memory after extraction
1795
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 rhash_entries= [KNL,NET]
1797 Set number of hash buckets for route cache
1798
1799 riscom8= [HW,SERIAL]
1800 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1801
1802 ro [KNL] Mount root device read-only on boot
1803
1804 root= [KNL] Root filesystem
1805
1806 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1807 mount the root filesystem
1808
1809 rootflags= [KNL] Set root filesystem mount option string
1810
1811 rootfstype= [KNL] Set root filesystem type
1812
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001813 rootwait [KNL] Wait (indefinitely) for root device to show up.
1814 Useful for devices that are detected asynchronously
1815 (e.g. USB and MMC devices).
1816
James Morris20510f22007-10-16 23:31:32 -07001817 root_plug.vendor_id=
1818 [ROOTPLUG] Override the default vendor ID
1819
1820 root_plug.product_id=
1821 [ROOTPLUG] Override the default product ID
1822
1823 root_plug.debug=
1824 [ROOTPLUG] Enable debugging output
1825
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 rw [KNL] Mount root device read-write on boot
1827
1828 S [KNL] Run init in single mode
1829
1830 sa1100ir [NET]
1831 See drivers/net/irda/sa1100_ir.c.
1832
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001834
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1836 Format: <io>[,<timeout>[,<isapnp>]]
1837
1838 scsi_debug_*= [SCSI]
1839 See drivers/scsi/scsi_debug.c.
1840
1841 scsi_default_dev_flags=
1842 [SCSI] SCSI default device flags
1843 Format: <integer>
1844
1845 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1846 Format: <vendor>:<model>:<flags>
1847 (flags are integer value)
1848
Randy Dunlap6af66322007-11-14 16:52:25 -08001849 scsi_logging_level= [SCSI] a bit mask of logging levels
1850 See drivers/scsi/scsi_logging.h for bits. Also
1851 settable via sysctl at dev.scsi.logging_level
1852 (/proc/sys/dev/scsi/logging_level).
1853 There is also a nice 'scsi_logging_level' script in the
1854 S390-tools package, available for download at
1855 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001857 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1858 discovered. async scans them in kernel threads,
1859 allowing boot to proceed. none ignores them, expecting
1860 user space to do the scan.
1861
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 selinux [SELINUX] Disable or enable SELinux at boot time.
1863 Format: { "0" | "1" }
1864 See security/selinux/Kconfig help text.
1865 0 -- disable.
1866 1 -- enable.
1867 Default value is set via kernel config option.
1868 If enabled at boot time, /selinux/disable can be used
1869 later to disable prior to initial policy load.
1870
James Morris4e5ab4c2006-06-09 00:33:33 -07001871 selinux_compat_net =
1872 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001873 Format: { "0" | "1" }
1874 0 -- use new secmark-based packet controls
1875 1 -- use legacy packet controls
1876 Default value is 0 (preferred).
1877 Value can be changed at runtime via
1878 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001879
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001880 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 shapers= [NET]
1883 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001884
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885 sim710= [SCSI,HW]
1886 See header of drivers/scsi/sim710.c.
1887
1888 simeth= [IA-64]
1889 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001890
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891 slram= [HW,MTD]
1892
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001893 slub_debug[=options[,slabs]] [MM, SLUB]
1894 Enabling slub_debug allows one to determine the
1895 culprit if slab objects become corrupted. Enabling
1896 slub_debug can create guard zones around objects and
1897 may poison objects when not in use. Also tracks the
1898 last alloc / free. For more information see
1899 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001900
1901 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001902 Determines the maximum allowed order for slabs.
1903 A high setting may cause OOMs due to memory
1904 fragmentation. For more information see
1905 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001906
1907 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001908 The minimum number of objects per slab. SLUB will
1909 increase the slab order up to slub_max_order to
1910 generate a sufficiently large slab able to contain
1911 the number of objects indicated. The higher the number
1912 of objects the smaller the overhead of tracking slabs
1913 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001914 For more information see Documentation/vm/slub.txt.
1915
1916 slub_min_order= [MM, SLUB]
1917 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001918 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001919 For more information see Documentation/vm/slub.txt.
1920
1921 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001922 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07001923 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001924 allocs to different slabs. Debug options disable
1925 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001926 For more information see Documentation/vm/slub.txt.
1927
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 smart2= [HW]
1929 Format: <io1>[,<io2>[,...,<io8>]]
1930
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001931 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001932 attempt to substitute SMP alternatives once at boot.
1933
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001934 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1935 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1936 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1937 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1938 smsc-ircc2.ircc_irq= [HW] IRQ line
1939 smsc-ircc2.ircc_dma= [HW] DMA channel
1940 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1941 0: Toshiba Satellite 1800 (GP data pin select)
1942 1: Fast pin select (default)
1943 2: ATC IRMode
1944
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 snd-ad1816a= [HW,ALSA]
1946
1947 snd-ad1848= [HW,ALSA]
1948
1949 snd-ali5451= [HW,ALSA]
1950
1951 snd-als100= [HW,ALSA]
1952
1953 snd-als4000= [HW,ALSA]
1954
1955 snd-azt2320= [HW,ALSA]
1956
1957 snd-cmi8330= [HW,ALSA]
1958
1959 snd-cmipci= [HW,ALSA]
1960
1961 snd-cs4231= [HW,ALSA]
1962
1963 snd-cs4232= [HW,ALSA]
1964
1965 snd-cs4236= [HW,ALSA]
1966
1967 snd-cs4281= [HW,ALSA]
1968
1969 snd-cs46xx= [HW,ALSA]
1970
1971 snd-dt019x= [HW,ALSA]
1972
1973 snd-dummy= [HW,ALSA]
1974
1975 snd-emu10k1= [HW,ALSA]
1976
1977 snd-ens1370= [HW,ALSA]
1978
1979 snd-ens1371= [HW,ALSA]
1980
1981 snd-es968= [HW,ALSA]
1982
1983 snd-es1688= [HW,ALSA]
1984
1985 snd-es18xx= [HW,ALSA]
1986
1987 snd-es1938= [HW,ALSA]
1988
1989 snd-es1968= [HW,ALSA]
1990
1991 snd-fm801= [HW,ALSA]
1992
1993 snd-gusclassic= [HW,ALSA]
1994
1995 snd-gusextreme= [HW,ALSA]
1996
1997 snd-gusmax= [HW,ALSA]
1998
1999 snd-hdsp= [HW,ALSA]
2000
2001 snd-ice1712= [HW,ALSA]
2002
2003 snd-intel8x0= [HW,ALSA]
2004
2005 snd-interwave= [HW,ALSA]
2006
2007 snd-interwave-stb=
2008 [HW,ALSA]
2009
2010 snd-korg1212= [HW,ALSA]
2011
2012 snd-maestro3= [HW,ALSA]
2013
2014 snd-mpu401= [HW,ALSA]
2015
2016 snd-mtpav= [HW,ALSA]
2017
2018 snd-nm256= [HW,ALSA]
2019
2020 snd-opl3sa2= [HW,ALSA]
2021
2022 snd-opti92x-ad1848=
2023 [HW,ALSA]
2024
2025 snd-opti92x-cs4231=
2026 [HW,ALSA]
2027
2028 snd-opti93x= [HW,ALSA]
2029
2030 snd-pmac= [HW,ALSA]
2031
2032 snd-rme32= [HW,ALSA]
2033
2034 snd-rme96= [HW,ALSA]
2035
2036 snd-rme9652= [HW,ALSA]
2037
2038 snd-sb8= [HW,ALSA]
2039
2040 snd-sb16= [HW,ALSA]
2041
2042 snd-sbawe= [HW,ALSA]
2043
2044 snd-serial= [HW,ALSA]
2045
2046 snd-sgalaxy= [HW,ALSA]
2047
2048 snd-sonicvibes= [HW,ALSA]
2049
2050 snd-sun-amd7930=
2051 [HW,ALSA]
2052
2053 snd-sun-cs4231= [HW,ALSA]
2054
2055 snd-trident= [HW,ALSA]
2056
2057 snd-usb-audio= [HW,ALSA,USB]
2058
2059 snd-via82xx= [HW,ALSA]
2060
2061 snd-virmidi= [HW,ALSA]
2062
2063 snd-wavefront= [HW,ALSA]
2064
2065 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002066
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002067 softlockup_panic=
2068 [KNL] Should the soft-lockup detector generate panics.
2069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2071 See Documentation/sonypi.txt
2072
2073 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2074 See Documentation/specialix.txt.
2075
2076 spia_io_base= [HW,MTD]
2077 spia_fio_base=
2078 spia_pedr=
2079 spia_peddr=
2080
2081 sscape= [HW,OSS]
2082 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002083
Linus Torvalds1da177e2005-04-16 15:20:36 -07002084 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2085 See Documentation/scsi/st.txt.
2086
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 sti= [PARISC,HW]
2088 Format: <num>
2089 Set the STI (builtin display/keyboard on the HP-PARISC
2090 machines) console (graphic card) which should be used
2091 as the initial boot-console.
2092 See also comment in drivers/video/console/sticore.c.
2093
2094 sti_font= [HW]
2095 See comment in drivers/video/console/sticore.c.
2096
2097 stifb= [HW]
2098 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2099
Greg Banks42a7fc42007-03-06 01:42:23 -08002100 sunrpc.pool_mode=
2101 [NFS]
2102 Control how the NFS server code allocates CPUs to
2103 service thread pools. Depending on how many NICs
2104 you have and where their interrupts are bound, this
2105 option will affect which CPUs will do NFS serving.
2106 Note: this parameter cannot be changed while the
2107 NFS server is running.
2108
2109 auto the server chooses an appropriate mode
2110 automatically using heuristics
2111 global a single global pool contains all CPUs
2112 percpu one pool for each CPU
2113 pernode one pool for each NUMA node (equivalent
2114 to global on non-NUMA machines)
2115
Linus Torvalds1da177e2005-04-16 15:20:36 -07002116 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002117
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 switches= [HW,M68k]
2119
2120 sym53c416= [HW,SCSI]
2121 See header of drivers/scsi/sym53c416.c.
2122
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002123 sysrq_always_enabled
2124 [KNL]
2125 Ignore sysrq setting - this boot parameter will
2126 neutralize any effect of /proc/sys/kernel/sysrq.
2127 Useful for debugging.
2128
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 t128= [HW,SCSI]
2130 See header of drivers/scsi/t128.c.
2131
2132 tdfx= [HW,DRM]
2133
David Brownell77437fd2008-07-23 21:28:33 -07002134 test_suspend= [SUSPEND]
2135 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2136 standby suspend) as the system sleep state to briefly
2137 enter during system startup. The system is woken from
2138 this state using a wakeup-capable RTC alarm.
2139
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 thash_entries= [KNL,NET]
2141 Set number of hash buckets for TCP connection
2142
Len Brownf8707ec2007-08-12 00:12:54 -04002143 thermal.act= [HW,ACPI]
2144 -1: disable all active trip points in all thermal zones
2145 <degrees C>: override all lowest active trip points
2146
Len Brownc52a7412007-08-14 15:49:32 -04002147 thermal.crt= [HW,ACPI]
2148 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002149 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002150
Len Brownf5487142007-08-12 00:12:44 -04002151 thermal.nocrt= [HW,ACPI]
2152 Set to disable actions on ACPI thermal zone
2153 critical and hot trip points.
2154
Len Brown72b33ef2007-08-12 00:12:17 -04002155 thermal.off= [HW,ACPI]
2156 1: disable ACPI thermal control
2157
Len Browna70cdc52007-08-12 00:12:35 -04002158 thermal.psv= [HW,ACPI]
2159 -1: disable all passive trip points
2160 <degrees C>: override all passive trip points to this value
2161
Len Brown730ff342007-08-12 00:12:26 -04002162 thermal.tzp= [HW,ACPI]
2163 Specify global default ACPI thermal zone polling rate
2164 <deci-seconds>: poll all this frequency
2165 0: no polling (default)
2166
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 tmscsim= [HW,SCSI]
2168 See comment before function dc390_setup() in
2169 drivers/scsi/tmscsim.c.
2170
2171 tp720= [HW,PS2]
2172
2173 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002174 Format:
2175 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2176
Randy Dunlapa9913042005-10-23 12:57:11 -07002177 turbografx.map[2|3]= [HW,JOY]
2178 TurboGraFX parallel port interface
2179 Format:
2180 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 See also Documentation/input/joystick-parport.txt
2182
2183 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2184 See header of drivers/scsi/u14-34f.c.
2185
2186 uart401= [HW,OSS]
2187 Format: <io>,<irq>
2188
2189 uart6850= [HW,OSS]
2190 Format: <io>,<irq>
2191
Alan Stern5f8364b2006-12-05 16:29:55 -05002192 uhci-hcd.ignore_oc=
2193 [USB] Ignore overcurrent events (default N).
2194 Some badly-designed motherboards generate lots of
2195 bogus events, for ports that aren't wired to
2196 anything. Set this parameter to avoid log spamming.
2197 Note that genuine overcurrent events won't be
2198 reported either.
2199
Simon Arlotte3a61b02008-07-19 23:32:54 +01002200 unknown_nmi_panic
2201 [X86-32,X86-64]
2202 Set unknown_nmi_panic=1 early on boot.
2203
Alan Sternb5e795f2007-02-20 15:00:53 -05002204 usbcore.autosuspend=
2205 [USB] The autosuspend time delay (in seconds) used
2206 for newly-detected USB devices (default 2). This
2207 is the time required before an idle device will be
2208 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002209 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002210
Linus Torvalds1da177e2005-04-16 15:20:36 -07002211 usbhid.mousepoll=
2212 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002213
Paul Jackson200001e2008-06-25 05:44:46 -07002214 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2215 kernel's map of available physical RAM.
2216
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002217 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002218 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002219 vdso=1: enable VDSO (default)
2220 vdso=0: disable VDSO mapping
2221
Roland McGrathaf65d642008-01-30 13:30:43 +01002222 vdso32= [X86-32,X86-64]
2223 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2224 vdso32=1: enable 32-bit VDSO (default)
2225 vdso32=0: disable 32-bit VDSO mapping
2226
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002227 vector= [IA-64,SMP]
2228 vector=percpu: enable percpu vector domain
2229
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230 video= [FB] Frame buffer configuration
2231 See Documentation/fb/modedb.txt.
2232
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002233 vga= [BOOT,X86-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07002234 See Documentation/i386/boot.txt and
2235 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002236 Use vga=ask for menu.
2237 This is actually a boot loader parameter; the value is
2238 passed to the kernel using a special protocol.
2239
Randy Dunlapa9913042005-10-23 12:57:11 -07002240 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 size of <nn>. This can be used to increase the
2242 minimum size (128MB on x86). It can also be used to
2243 decrease the size and leave more room for directly
2244 mapped kernel RAM.
2245
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002246 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2247 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002249 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2250 Format: <command>
2251
2252 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2253 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002254
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 waveartist= [HW,OSS]
2256 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002257
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 wd33c93= [HW,SCSI]
2259 See header of drivers/scsi/wd33c93.c.
2260
2261 wd7000= [HW,SCSI]
2262 See header of drivers/scsi/wd7000.c.
2263
2264 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002265 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266
2267 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2268 xd_geo= See header of drivers/block/xd.c.
2269
2270 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002271 Format:
2272 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273
Andi Kleena62eaf12006-02-16 23:41:58 +01002274 norandmaps Don't use address space randomization
2275 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2276
Randy Dunlapa9913042005-10-23 12:57:11 -07002277______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278
2279TODO:
2280
2281 Add documentation for ALSA options.
2282 Add more DRM drivers.