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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.
Randy Dunlapa9913042005-10-23 12:57:11 -070090 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -070099 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
103
104In addition, the following text indicates that the option:
105
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
109
110Parameters denoted with BOOT are actually interpreted by the boot
111loader, and have no meaning to the kernel directly.
112Do not modify the syntax of boot loader parameters without extreme
113need or coordination with <Documentation/i386/boot.txt>.
114
Karsten Weiss55588702007-02-13 13:26:21 +0100115There are also arch-specific kernel-parameters not documented here.
116See for example <Documentation/x86_64/boot-options.txt>.
117
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119a trailing = on the name of any parameter states that that parameter will
120be entered as an environment variable, whereas its absence indicates that
121it will appear as a kernel argument readable via /proc/cmdline by programs
122running once the system is up.
123
jens m. noedler9c4751f2006-09-29 02:00:27 -0700124The number of kernel parameters is not limited, but the length of the
125complete command line (parameters including spaces etc.) is limited to
126a fixed number of characters. This limit depends on the architecture
127and is between 256 and 4096 characters. It is defined in the file
128./include/asm/setup.h as COMMAND_LINE_SIZE.
129
130
Bernhard Walle03d926f2007-03-06 02:29:44 -0800131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700133 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700138 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 strictly ACPI specification compliant.
140
Randy Dunlap53471122008-03-12 18:10:51 -0400141 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
Len Browna1fdcc02007-03-11 03:26:14 -0400143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400147 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400148
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 acpi_sleep= [HW,ACPI] Sleep options
Pavel Machek23b168d2008-02-05 19:27:12 +0100150 Format: { s3_bios, s3_mode, s3_beep }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
Randy Dunlapa9913042005-10-23 12:57:11 -0700154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700156 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Randy Dunlapa9913042005-10-23 12:57:11 -0700158 acpi_irq_balance [HW,ACPI]
159 ACPI will balance active IRQs
160 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Randy Dunlapa9913042005-10-23 12:57:11 -0700162 acpi_irq_nobalance [HW,ACPI]
163 ACPI will not move active IRQs (default)
164 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Randy Dunlapa9913042005-10-23 12:57:11 -0700166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
167 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 Format: <irq>,<irq>...
169
Randy Dunlapa9913042005-10-23 12:57:11 -0700170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 Format: <irq>,<irq>...
172
Len Brown67effe82007-07-26 00:50:06 -0400173 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
174
Len Browna1f9e652006-01-25 23:47:36 -0500175 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
176 Format: To spoof as Windows 98: ="Microsoft Windows"
177
Len Brownae00d812007-05-29 18:43:33 -0400178 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
179 acpi_osi="string1" # add string1 -- only one string
180 acpi_osi="!string2" # remove built-in string2
181 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
183 acpi_serialize [HW,ACPI] force serialization of AML methods
184
185 acpi_skip_timer_override [HW,ACPI]
186 Recognize and ignore IRQ0/pin2 Interrupt Override.
187 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100188 acpi_use_timer_override [HW,ACPI}
189 Use timer override. For some broken Nvidia NF5 boards
190 that require a timer override, but don't have
191 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
Zhang Ruif9891062007-04-24 13:53:22 +0800193 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700195 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 1: enable, 0: disable. It is useful for boot time
197 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800198 via /sys/module/acpi/parameters/debug_layer.
199 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
200 Available bits (add the numbers together) to enable debug output
201 for specific parts of the ACPI subsystem:
202 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
203 0x10 namespace 0x20 parser 0x40 dispatcher
204 0x80 executer 0x100 resources 0x200 acpica debugger
205 0x400 os services 0x800 acpica disassembler.
206 The number can be in decimal or prefixed with 0x in hex.
207 Warning: Many of these options can produce a lot of
208 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
Zhang Ruif9891062007-04-24 13:53:22 +0800210 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700212 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 1: enable, 0: disable. It is useful for boot time
214 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800215 via /sys/module/acpi/parameters/debug_level.
216 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
217 Available bits (add the numbers together) to enable different
218 debug output levels of the ACPI subsystem:
219 0x01 error 0x02 warn 0x04 init 0x08 debug object
220 0x10 info 0x20 init names 0x40 parse 0x80 load
221 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
222 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
223 0x10000 resources 0x20000 user requests 0x40000 package.
224 The number can be in decimal or prefixed with 0x in hex.
225 Warning: Many of these options can produce a lot of
226 output and make your system unusable. Be very careful.
227
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700228 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000233 agp= [AGP]
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
238
Chuck Ebbert66759a02005-09-12 18:49:25 +0200239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200243 The kernel tries to set a reasonable default.
244
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
248
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 ad1848= [HW,OSS]
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
251
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 advansys= [HW,SCSI]
253 See header of drivers/scsi/advansys.c.
254
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
257
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700261
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 aha152x= [HW,SCSI]
263 See Documentation/scsi/aha152x.txt.
264
265 aha1542= [HW,SCSI]
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
267
268 aic7xxx= [HW,SCSI]
269 See Documentation/scsi/aic7xxx.txt.
270
271 aic79xx= [HW,SCSI]
272 See Documentation/scsi/aic79xx.txt.
273
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
276 Format: <a>,<b>
277 See also Documentation/kernel/input/joystick.txt
278
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
283
Randy Dunlapa9913042005-10-23 12:57:11 -0700284 apc= [HW,SPARC]
285 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 Format: noidle
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
290
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700296
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
299
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
302
303 ataflop= [HW,M68k]
304
305 atarimouse= [HW,MOUSE] Atari Mouse
306
307 atascsi= [HW,SCSI] Atari SCSI
308
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
311
312 atkbd.reset= [HW] Reset keyboard during initialization
313
Randy Dunlapa9913042005-10-23 12:57:11 -0700314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 keyboards
319
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700322
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
326 autotest [IA64]
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 baycom_epp= [HW,AX25]
329 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
332 Format: <io>,<mode>
333 See header of drivers/net/hamradio/baycom_par.c.
334
Randy Dunlapa9913042005-10-23 12:57:11 -0700335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
339
Randy Dunlapa9913042005-10-23 12:57:11 -0700340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
344
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700345 boot_delay= Milliseconds to delay each printk during boot.
346 Values larger than 10 seconds (10000) are changed to
347 no delay (0).
348 Format: integer
349
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700351 bttv.radio= Most important insmod options are available as
352 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
355
356 BusLogic= [HW,SCSI]
357 See drivers/scsi/BusLogic.c, comment before function
358 BusLogic_ParseDriverOptions().
359
360 c101= [NET] Moxa C101 synchronous serial card
361
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 Sometimes CPU hardware bugs make them report the cache
364 size incorrectly. The kernel will attempt work arounds
365 to fix known problems, but for some CPUs it is not
366 possible to determine what the correct size should be.
367 This option provides an override for these situations.
368
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200369 security= [SECURITY] Choose a security module to enable at boot.
370 If this boot parameter is not specified, only the first
371 security module asking for security registration will be
372 loaded. An invalid security module name will be treated
373 as if no module has been chosen.
374
James Morris20510f22007-10-16 23:31:32 -0700375 capability.disable=
376 [SECURITY] Disable capabilities. This would normally
377 be used only if an alternative security model is to be
378 configured. Potentially dangerous and should only be
379 used if you are entirely sure of the consequences.
380
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100381 ccw_timeout_log [S390]
382 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
Paul Menage8bab8dd2008-04-04 14:29:57 -0700384 cgroup_disable= [KNL] Disable a particular controller
385 Format: {name of the controller(s) to disable}
386 {Currently supported controllers - "memory"}
387
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 checkreqprot [SELINUX] Set initial checkreqprot flag value.
389 Format: { "0" | "1" }
390 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700391 0 -- check protection applied by kernel (includes
392 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 1 -- check protection requested by application.
394 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700395 Value can be changed at runtime via
396 /selinux/checkreqprot.
397
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100398 cio_ignore= [S390]
399 See Documentation/s390/CommonIO for details.
400
401 cio_msg= [S390]
402 See Documentation/s390/CommonIO for details.
403
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700404 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700405 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200406 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700407 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200408 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 Format: { pit | tsc | cyclone | pmtmr }
410
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700411 clocksource= [GENERIC_TIME] Override the default clocksource
412 Format: <string>
413 Override the default clocksource and use the clocksource
414 with the name specified.
415 Some clocksource names to choose from, depending on
416 the platform:
417 [all] jiffies (this is the base, fallback clocksource)
418 [ACPI] acpi_pm
419 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
420 pxa_timer,timer3,32k_counter,timer0_1
421 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700422 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700423 scx200_hrt on Geode; cyclone on IBM x440
424 [MIPS] MIPS
425 [PARISC] cr16
426 [S390] tod
427 [SH] SuperH
428 [SPARC64] tick
429 [X86-64] hpet,tsc
430
Andi Kleenac72e782008-01-30 13:33:21 +0100431 clearcpuid=BITNUM [X86]
432 Disable CPUID feature X for the kernel. See
433 include/asm-x86/cpufeature.h for the valid bit numbers.
434 Note the Linux specific bits are not necessarily
435 stable over kernel options, but the vendor specific
436 ones should be.
437 Also note that user programs calling CPUID directly
438 or using the feature without checking anything
439 will still see it. This just prevents it from
440 being used by the kernel or shown in /proc/cpuinfo.
441 Also note the kernel might malfunction if you disable
442 some critical bits.
443
Arjan van de Vena25bd942008-01-30 13:33:08 +0100444 code_bytes [IA32/X86_64] How many bytes of object code to print
445 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100446 Range: 0 - 8192
447 Default: 64
448
Andi Kleenf9262c12006-03-08 17:57:25 -0800449 disable_8254_timer
450 enable_8254_timer
451 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
452 over the 8254 in addition to over the IO-APIC. The
453 kernel tries to set a sensible default.
454
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200455 hpet= [X86-32,HPET] option to control HPET usage
456 Format: { enable (default) | disable | force }
457 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100458 force: allow force enabled of undocumented chips (ICH4,
459 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700462 Format:
463 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464
465 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
466 Format: <io>[,<irq>]
467
Randy Dunlapa9913042005-10-23 12:57:11 -0700468 com90xx= [HW,NET]
469 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 Format: <io>[,<irq>[,<memstart>]]
471
472 condev= [HW,S390] console device
473 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700474
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 console= [KNL] Output console device and options.
476
477 tty<n> Use the virtual console device <n>.
478
479 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800480 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800482 the form "bbbbpnf", where "bbbb" is the baud rate,
483 "p" is parity ("n", "o", or "e"), "n" is number of
484 bits, and "f" is flow control ("r" for RTS or
485 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800487 See Documentation/serial-console.txt for more
488 information. See
489 Documentation/networking/netconsole.txt for an
490 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700492 uart[8250],io,<addr>[,options]
493 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 Start an early, polled-mode console on the 8250/16550
495 UART at the specified I/O port or MMIO address,
496 switching to the matching ttyS device later. The
497 options are the same as for ttyS, above.
498
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700499 earlycon= [KNL] Output early console device and options.
500 uart[8250],io,<addr>[,options]
501 uart[8250],mmio,<addr>[,options]
502 Start an early, polled-mode console on the 8250/16550
503 UART at the specified I/O port or MMIO address.
504 The options are the same as for ttyS, above.
505
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700506 no_console_suspend
507 [HW] Never suspend the console
508 Disable suspending of consoles during suspend and
509 hibernate operations. Once disabled, debugging
510 messages can reach various consoles while the rest
511 of the system is being put to sleep (ie, while
512 debugging driver suspend/resume hooks). This may
513 not work reliably with all consoles, but is known
514 to work with serial and VGA consoles.
515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700517 Format:
518 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700520 crashkernel=nn[KMG]@ss[KMG]
521 [KNL] Reserve a chunk of physical memory to
522 hold a kernel to switch to with kexec on panic.
523
Bernhard Wallefb391592007-10-18 23:41:02 -0700524 crashkernel=range1:size1[,range2:size2,...][@offset]
525 [KNL] Same as above, but depends on the memory
526 in the running system. The syntax of range is
527 start-[end] where start and end are both
528 a memory unit (amount[KMG]). See also
529 Documentation/kdump/kdump.txt for a example.
530
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 cs4232= [HW,OSS]
532 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
533
534 cs89x0_dma= [HW,NET]
535 Format: <dma>
536
537 cs89x0_media= [HW,NET]
538 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700539
Randy Dunlapa9913042005-10-23 12:57:11 -0700540 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 See header of drivers/s390/block/dasd_devmap.c.
542
543 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
544 (one device per port)
545 Format: <port#>,<type>
546 See also Documentation/input/joystick-parport.txt
547
548 debug [KNL] Enable kernel debugging (events log level).
549
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700550 debug_locks_verbose=
551 [KNL] verbose self-tests
552 Format=<0|1>
553 Print debugging info while doing the locking API
554 self-tests.
555 We default to 0 (no extra messages), setting it to
556 1 will print _a lot_ more information - normally
557 only useful to kernel developers.
558
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200559 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 Format: <area>[,<node>]
561 See also Documentation/networking/decnet.txt.
562
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000563 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700564 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
565 Change the default blue palette of the console.
566 This is a 16-member array composed of values
567 ranging from 0-255.
568
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000569 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700570 Format: <green0>,<green1>,<green2>,...,<green15>
571 Change the default green palette of the console.
572 This is a 16-member array composed of values
573 ranging from 0-255.
574
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000575 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700576 Format: <red0>,<red1>,<red2>,...,<red15>
577 Change the default red palette of the console.
578 This is a 16-member array composed of values
579 ranging from 0-255.
580
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000581 vt.default_utf8=
582 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700583 Format=<0|1>
584 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000585 Default is 1, i.e. UTF-8 mode is enabled for all
586 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700587
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 dhash_entries= [KNL]
589 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700590
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 digi= [HW,SERIAL]
592 IO parameters + enable/disable command.
593
594 digiepca= [HW,SERIAL]
595 See drivers/char/README.epca and
596 Documentation/digiepca.txt.
597
Yinghai Lu093af8d2008-01-30 13:33:32 +0100598 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100599 By default the kernel will trim any uncacheable
600 memory out of your available memory pool based on
601 MTRR settings. This parameter disables that behavior,
602 possibly causing your machine to run very slowly.
603
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 dmasound= [HW,OSS] Sound subsystem buffers
605
606 dscc4.setup= [NET]
607
608 dtc3181e= [HW,SCSI]
609
Robin Getz0ae53642007-10-09 17:24:49 +0800610 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 earlyprintk=vga
612 earlyprintk=serial[,ttySn[,baudrate]]
613
Randy Dunlapa9913042005-10-23 12:57:11 -0700614 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 takes over.
616
617 Only vga or serial at a time, not both.
618
619 Currently only ttyS0 and ttyS1 are supported.
620
621 Interaction with the standard serial driver is not
622 very good.
623
624 The VGA output is eventually overwritten by the real
625 console.
626
627 eata= [HW,SCSI]
628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 edd= [EDD]
630 Format: {"of[f]" | "sk[ipmbr]"}
631 See comment in arch/i386/boot/edd.S
632
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 eisa_irq_edge= [PARISC,HW]
634 See header of drivers/parisc/eisa.c.
635
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700636 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 See comment before function elanfreq_setup() in
638 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
639
640 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800641 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700642 See Documentation/block/as-iosched.txt and
643 Documentation/block/deadline-iosched.txt for details.
644
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700645 elfcorehdr= [X86-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700646 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800647 image elf header. Generally kexec loader will
648 pass this option to capture kernel.
649 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650
651 enforcing [SELINUX] Set initial enforcing status.
652 Format: {"0" | "1"}
653 See security/selinux/Kconfig help text.
654 0 -- permissive (log only, no denials).
655 1 -- enforcing (deny and log).
656 Default value is 0.
657 Value can be changed at runtime via /selinux/enforce.
658
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 es1371= [HW,OSS]
660 Format: <spdif>,[<nomix>,[<amplifier>]]
661 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700662
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 ether= [HW,NET] Ethernet cards parameters
664 This option is obsoleted by the "netdev=" option, which
665 has equivalent usage. See its documentation for details.
666
667 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
668 Format: <io>[,<irq>]
669
Akinobu Mitade1ba092006-12-08 02:39:42 -0800670 failslab=
671 fail_page_alloc=
672 fail_make_request=[KNL]
673 General fault injection mechanism.
674 Format: <interval>,<probability>,<space>,<times>
675 See also /Documentation/fault-injection/.
676
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 fd_mcs= [HW,SCSI]
678 See header of drivers/scsi/fd_mcs.c.
679
680 fdomain= [HW,SCSI]
681 See header of drivers/scsi/fdomain.c.
682
683 floppy= [HW]
684 See Documentation/floppy.txt.
685
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 gamecon.map[2|3]=
687 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
688 support via parallel port (up to 5 devices per port)
689 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
690 See also Documentation/input/joystick-parport.txt
691
692 gamma= [HW,DRM]
693
Yinghai Luaaf23042008-01-30 13:33:09 +0100694 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
695 Format: off | on
696 default: on
697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 gdth= [HW,SCSI]
699 See header of drivers/scsi/gdth.c.
700
701 gpt [EFI] Forces disk with valid GPT signature but
702 invalid Protective MBR to be treated as GPT.
703
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 gvp11= [HW,SCSI]
705
706 hashdist= [KNL,NUMA] Large hashes allocated during boot
707 are distributed across NUMA nodes. Defaults on
708 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700709 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710
711 hcl= [IA-64] SGI's Hardware Graph compatibility layer
712
713 hd= [EIDE] (E)IDE hard drive subsystem geometry
714 Format: <cyl>,<head>,<sect>
715
716 hd?= [HW] (E)IDE subsystem
Randy Dunlap1c10e932008-03-07 21:53:50 +0100717 hd?lun= See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718
719 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
720 size of <nn>. This works even on boxes that have no
721 highmem otherwise. This also works to reduce highmem
722 size on bigger boxes.
723
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800724 highres= [KNL] Enable/disable high resolution timer mode.
725 Valid parameters: "on", "off"
726 Default: "on"
727
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 hisax= [HW,ISDN]
729 See Documentation/isdn/README.HiSax.
730
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700731 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
Jon Tollefson4ec161c2008-01-04 09:59:50 +1100732 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200735 i8042.dumbkbd [HW] Pretend that controller can only read data from
736 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 (Don't attempt to blink the leds)
738 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500739 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400740 i8042.noloop [HW] Disable the AUX Loopback command while probing
741 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 i8042.nomux [HW] Don't check presence of an active multiplexing
743 controller
744 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
745 controllers
746 i8042.panicblink=
747 [HW] Frequency with which keyboard LEDs should blink
748 when kernel panics (default is 0.5 sec)
749 i8042.reset [HW] Reset the controller during init and cleanup
750 i8042.unlock [HW] Unlock (ignore) the keylock
751
752 i810= [HW,DRM]
753
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700754 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
755 indicates that the driver is running on unsupported
756 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
758 does not match list of supported models.
759 i8k.power_status
760 [HW] Report power status in /proc/i8k
761 (disabled by default)
762 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
763 capability is set.
764
765 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
766 See Documentation/mca.txt.
767
768 icn= [HW,ISDN]
769 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
770
771 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200772 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100773 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
775 ide?= [HW] (E)IDE subsystem
Bartlomiej Zolnierkiewiczf01674e2008-04-18 00:46:35 +0200776 Format: ide?=ata66 or chipset specific parameters.
Randy Dunlap1c10e932008-03-07 21:53:50 +0100777 See Documentation/ide/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100780 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
Andi Kleenf039b752007-05-02 19:27:12 +0200782 idle= [X86]
783 Format: idle=poll or idle=mwait
784 Poll forces a polling idle loop that can slightly improves the performance
785 of waking up a idle CPU, but will use a lot of power and make the system
786 run hot. Not recommended.
787 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
788 to not use it because it doesn't save as much power as a normal idle
789 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
790 as idle=poll.
Randy Dunlapa9913042005-10-23 12:57:11 -0700791
Denis Cheng594765a2008-02-06 02:57:49 +0100792 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
793 Claim all unknown PCI IDE storage controllers.
794
Ingo Molnar792908222006-12-06 20:40:51 -0800795 ignore_loglevel [KNL]
796 Ignore loglevel setting - this will print /all/
797 kernel messages to the console. Useful for debugging.
798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 ihash_entries= [KNL]
800 Set number of hash buckets for inode cache.
801
802 in2000= [HW,SCSI]
803 See header of drivers/scsi/in2000.c.
804
805 init= [KNL]
806 Format: <full_path>
807 Run specified binary instead of /sbin/init as init
808 process.
809
810 initcall_debug [KNL] Trace initcalls as they are executed. Useful
811 for working out where the kernel is dying during
812 startup.
813
814 initrd= [BOOT] Specify the location of the initial ramdisk
815
816 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
817 Format: <irq>
818
819 inttest= [IA64]
820
Pavel Machekb552da82008-03-19 15:58:11 +0100821 iommu= [x86]
822 off
823 force
824 noforce
825 biomerge
826 panic
827 nopanic
828 merge
829 nomerge
830 forcesac
831 soft
832
833
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700834 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
835 off
836 Disable intel iommu driver.
837 igfx_off [Default Off]
838 By default, gfx is mapped as normal device. If a gfx
839 device has a dedicated DMAR unit, the DMAR unit is
840 bypassed by not enabling DMAR with this option. In
841 this case, gfx device will use physical address for
842 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700843 forcedac [x86_64]
844 With this option iommu will not optimize to look
845 for io virtual address below 32 bit forcing dual
846 address cycle on pci bus for cards supporting greater
847 than 32 bit addressing. The default is to look
848 for translation below 32 bit and if not available
849 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800850 strict [Default Off]
851 With this option on every unmap_single operation will
852 result in a hardware IOTLB flush operation as opposed
853 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700854
Rene Hermanb02aae92008-01-30 13:30:05 +0100855 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100856 0x80
857 Standard port 0x80 based delay
858 0xed
859 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100860 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100861 Simple two microseconds delay
862 none
863 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100864
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 io7= [HW] IO7 for Marvel based alpha systems
866 See comment before marvel_specify_io7 in
867 arch/alpha/kernel/core_marvel.c.
868
869 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400870 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871
872 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700873 See comment before ip2_setup() in
874 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875
876 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
877 See header of drivers/scsi/ips.c.
878
Simon Horman72c4a132006-09-13 19:57:18 -0700879 ports= [IP_VS_FTP] IPVS ftp helper module
880 Default is 21.
881 Up to 8 (IP_VS_APP_MAX_PORTS) ports
882 may be specified.
883 Format: <port>,<port>....
884
Alan Cox200803d2005-06-28 20:45:18 -0700885 irqfixup [HW]
886 When an interrupt is not handled search all handlers
887 for it. Intended to get systems with badly broken
888 firmware running.
889
890 irqpoll [HW]
891 When an interrupt is not handled search all handlers
892 for it. Also check all handlers each timer
893 interrupt. Intended to get systems with badly broken
894 firmware running.
895
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700897 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898
899 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800900 Format:
901 <cpu number>,...,<cpu number>
902 or
903 <cpu number>-<cpu number> (must be a positive range in ascending order)
904 or a mixture
905 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 This option can be used to specify one or more CPUs
907 to isolate from the general SMP balancing and scheduling
908 algorithms. The only way to move a process onto or off
909 an "isolated" CPU is via the CPU affinity syscalls.
910 <cpu number> begins at 0 and the maximum value is
911 "number of CPUs in system - 1".
912
913 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700914 alternative -- manually setting the CPU mask of all
915 tasks in the system -- can cause problems and
916 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917
Randy Dunlapa9913042005-10-23 12:57:11 -0700918 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919
920 js= [HW,JOY] Analog joystick
921 See Documentation/input/joystick.txt.
922
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700923 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -0700924 specifies the amount of memory usable by the kernel
925 for non-movable allocations. The requested amount is
926 spread evenly throughout all nodes in the system. The
927 remaining memory in each node is used for Movable
928 pages. In the event, a node is too small to have both
929 kernelcore and Movable pages, kernelcore pages will
930 take priority and other nodes will have a larger number
931 of kernelcore pages. The Movable zone is used for the
932 allocation of pages that may be reclaimed or moved
933 by the page migration subsystem. This means that
934 HugeTLB pages may not be allocated from this zone.
935 Note that allocations like PTEs-from-HighMem still
936 use the HighMem zone if it exists, and the Normal
937 zone if it does not.
938
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700939 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -0700940 is similar to kernelcore except it specifies the
941 amount of memory used for migratable allocations.
942 If both kernelcore and movablecore is specified,
943 then kernelcore will be at *least* the specified
944 value but may be more. If movablecore on its own
945 is specified, the administrator must be careful
946 that the amount of memory usable for all allocations
947 is not too small.
948
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 keepinitrd [HW,ARM]
950
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700951 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 in oops dumps.
953
Jason Wessel6cdf6e02008-04-17 20:05:38 +0200954 kgdboc= [HW] kgdb over consoles.
955 Requires a tty driver that supports console polling.
956 (only serial suported for now)
957 Format: <serial_device>[,baud]
958
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 l2cr= [PPC]
960
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700961 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -0700962 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700964 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +0100965 C2 power state.
966
FD Camifcb71f62008-01-06 19:08:56 +0100967 libata.dma= [LIBATA] DMA control
968 libata.dma=0 Disable all PATA and SATA DMA
969 libata.dma=1 PATA and SATA Disk DMA only
970 libata.dma=2 ATAPI (CDROM) DMA only
971 libata.dma=4 Compact Flash DMA only
972 Combinations also work, so libata.dma=3 enables DMA
973 for disks and CDROMs, but not CFs.
974
Dave Jones78e70c22007-09-27 11:50:13 -0400975 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
976 when set.
977 Format: <int>
978
Tejun Heo33267322008-02-13 09:15:09 +0900979 libata.force= [LIBATA] Force configurations. The format is comma
980 separated list of "[ID:]VAL" where ID is
981 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
982 matching port, link or device. Basically, it matches
983 the ATA ID string printed on console by libata. If
984 the whole ID part is omitted, the last PORT and DEVICE
985 values are used. If ID hasn't been specified yet, the
986 configuration applies to all ports, links and devices.
987
988 If only DEVICE is omitted, the parameter applies to
989 the port and all links and devices behind it. DEVICE
990 number of 0 either selects the first device or the
991 first fan-out link behind PMP device. It does not
992 select the host link. DEVICE number of 15 selects the
993 host link and device attached to it.
994
995 The VAL specifies the configuration to force. As long
996 as there's no ambiguity shortcut notation is allowed.
997 For example, both 1.5 and 1.5G would work for 1.5Gbps.
998 The following configurations can be forced.
999
1000 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1001 Any ID with matching PORT is used.
1002
1003 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1004
1005 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1006 udma[/][16,25,33,44,66,100,133] notation is also
1007 allowed.
1008
1009 * [no]ncq: Turn on or off NCQ.
1010
1011 If there are multiple matching configurations changing
1012 the same attribute, the last one is used.
1013
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 load_ramdisk= [RAM] List of ramdisks to load from floppy
1015 See Documentation/ramdisk.txt.
1016
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001017 lockd.nlm_grace_period=P [NFS] Assign grace period.
1018 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001020 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1021 Format: <integer>
1022
1023 lockd.nlm_timeout=T [NFS] Assign timeout value.
1024 Format: <integer>
1025
1026 lockd.nlm_udpport=M [NFS] Assign UDP port.
1027 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028
1029 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1030 Format: <irq>
1031
1032 loglevel= All Kernel Messages with a loglevel smaller than the
1033 console loglevel will be printed to the console. It can
1034 also be changed with klogd or other programs. The
1035 loglevels are defined as follows:
1036
1037 0 (KERN_EMERG) system is unusable
1038 1 (KERN_ALERT) action must be taken immediately
1039 2 (KERN_CRIT) critical conditions
1040 3 (KERN_ERR) error conditions
1041 4 (KERN_WARNING) warning conditions
1042 5 (KERN_NOTICE) normal but significant condition
1043 6 (KERN_INFO) informational
1044 7 (KERN_DEBUG) debug-level messages
1045
1046 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001047 Format: { n | nk | nM }
1048 n must be a power of two. The default size
1049 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
Randy Dunlapaccaa242007-10-16 01:29:37 -07001051 logo.nologo [FB] Disables display of the built-in Linux logo.
1052 This may be used to provide more screen space for
1053 kernel log messages and is useful when debugging
1054 kernel boot problems.
1055
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 lp=0 [LP] Specify parallel ports to use, e.g,
1057 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1058 lp=reset first parallel port). 'lp=0' disables the
1059 lp=auto printer driver. 'lp=reset' (which can be
1060 specified in addition to the ports) causes
1061 attached printers to be reset. Using
1062 lp=port1,port2,... specifies the parallel ports
1063 to associate lp devices with, starting with
1064 lp0. A port specification may be 'none' to skip
1065 that lp device, or a parport name such as
1066 'parport0'. Specifying 'lp=auto' instead of a
1067 port specification list means that device IDs
1068 from each port should be examined, to see if
1069 an IEEE 1284-compliant printer is attached; if
1070 so, the driver will manage that printer.
1071 See also header of drivers/char/lp.c.
1072
1073 lpj=n [KNL]
1074 Sets loops_per_jiffy to given constant, thus avoiding
1075 time-consuming boot-time autodetection (up to 250 ms per
1076 CPU). 0 enables autodetection (default). To determine
1077 the correct value for your kernel, boot with normal
1078 autodetection and see what value is printed. Note that
1079 on SMP systems the preset will be applied to all CPUs,
1080 which is likely to cause problems if your CPUs need
1081 significantly divergent settings. An incorrect value
1082 will cause delays in the kernel to be wrong, leading to
1083 unpredictable I/O errors and other breakage. Although
1084 unlikely, in the extreme case this might damage your
1085 hardware.
1086
1087 ltpc= [NET]
1088 Format: <io>,<irq>,<dma>
1089
Randy Dunlapa9913042005-10-23 12:57:11 -07001090 mac5380= [HW,SCSI] Format:
1091 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092
Randy Dunlapa9913042005-10-23 12:57:11 -07001093 mac53c9x= [HW,SCSI] Format:
1094 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
Randy Dunlapa9913042005-10-23 12:57:11 -07001096 machvec= [IA64] Force the use of a particular machine-vector
1097 (machvec) in a generic kernel.
1098 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
Randy Dunlapa9913042005-10-23 12:57:11 -07001100 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 be mounted
1102 Format: <1-256>
1103
1104 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001105 should make use of. maxcpus=n : n >= 0 limits the
1106 kernel to using 'n' processors. n=0 is a special case,
1107 it is equivalent to "nosmp", which also disables
1108 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109
Bob Picco2b2c3752005-06-29 18:00:00 -07001110 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1111 equal to this physical address is ignored.
1112
Randy Dunlapa9913042005-10-23 12:57:11 -07001113 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 Should be between 1 and 2^32-1.
1115
1116 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001117 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 Should be between 1 and 16384.
1119
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 mcatest= [IA-64]
1121
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001122 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123
Andi Kleen909dd322007-10-17 18:04:38 +02001124 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1125
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 md= [HW] RAID subsystems devices and level
1127 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001128
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 mdacon= [MDA]
1130 Format: <first>,<last>
1131 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001132
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1134 Amount of memory to be used when the kernel is not able
1135 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001136 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 address space collisions. Without memmap= PCI devices
1138 could be placed at addresses belonging to unused RAM.
1139
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001140 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 memory.
1142
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001143 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144 E820 memory map, as specified by the user.
1145 Such memmap=exactmap lines can be constructed based on
1146 BIOS output or other requirements. See the memmap=nn@ss
1147 option description.
1148
1149 memmap=nn[KMG]@ss[KMG]
1150 [KNL] Force usage of a specific region of memory
1151 Region of memory to be used, from ss to ss+nn.
1152
1153 memmap=nn[KMG]#ss[KMG]
1154 [KNL,ACPI] Mark specific memory as ACPI data.
1155 Region of memory to be used, from ss to ss+nn.
1156
1157 memmap=nn[KMG]$ss[KMG]
1158 [KNL,ACPI] Mark specific memory as reserved.
1159 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001160 Example: Exclude memory from 0x18690000-0x1869ffff
1161 memmap=64K$0x18690000
1162 or
1163 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164
Yinghai Luc64df702008-03-21 18:56:19 -07001165 memtest= [KNL,X86_64] Enable memtest
1166 Format: <integer>
1167 range: 0,4 : pattern number
1168 default : 0 <disable>
1169
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 meye.*= [HW] Set MotionEye Camera parameters
1171 See Documentation/video4linux/meye.txt.
1172
Andres Salomon8f368812007-10-12 23:04:06 +02001173 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1174 Multi-Function General Purpose Timers on AMD Geode
1175 platforms.
1176
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001177 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1178 the BIOS has incorrectly applied a workaround. TinyBIOS
1179 version 0.98 is known to be affected, 0.99 fixes the
1180 problem by letting the user disable the workaround.
1181
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182 mga= [HW,DRM]
1183
1184 mousedev.tap_time=
1185 [MOUSE] Maximum time between finger touching and
1186 leaving touchpad surface for touch to be considered
1187 a tap and be reported as a left button click (for
1188 touchpads working in absolute mode only).
1189 Format: <msecs>
1190 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1191 reporting absolute coordinates, such as tablets
1192 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1193 reporting absolute coordinates, such as tablets
1194
1195 mpu401= [HW,OSS]
1196 Format: <io>,<irq>
1197
1198 MTD_Partition= [MTD]
1199 Format: <name>,<region-number>,<size>,<offset>
1200
Randy Dunlapa9913042005-10-23 12:57:11 -07001201 MTD_Region= [MTD] Format:
1202 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203
1204 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001205 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
1207 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001208 [HW] Make the MicroTouch USB driver use raw coordinates
1209 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210
1211 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1212
1213 NCR_D700= [HW,SCSI]
1214 See header of drivers/scsi/NCR_D700.c.
1215
1216 ncr5380= [HW,SCSI]
1217
1218 ncr53c400= [HW,SCSI]
1219
1220 ncr53c400a= [HW,SCSI]
1221
1222 ncr53c406a= [HW,SCSI]
1223
1224 ncr53c8xx= [HW,SCSI]
1225
1226 netdev= [NET] Network devices parameters
1227 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1228 Note that mem_start is often overloaded to mean
1229 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001230 This usage is only documented in each driver source
1231 file if at all.
1232
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001234 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235
1236 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001237 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238
Trond Myklebusta72b4422006-01-03 09:55:41 +01001239 nfs.callback_tcpport=
1240 [NFS] set the TCP port on which the NFSv4 callback
1241 channel should listen.
1242
Trond Myklebust58df0952006-01-03 09:55:57 +01001243 nfs.idmap_cache_timeout=
1244 [NFS] set the maximum lifetime for idmapper cache
1245 entries.
1246
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001247 nfs.enable_ino64=
1248 [NFS] enable 64-bit inode numbers.
1249 If zero, the NFS client will fake up a 32-bit inode
1250 number for the readdir() and stat() syscalls instead
1251 of returning the full 64-bit number.
1252 The default is to return 64-bit inode numbers.
1253
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001254 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1255 when a NMI is triggered.
1256 Format: [state][,regs][,debounce][,die]
1257
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001258 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001260 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 emulation library even if a 387 maths coprocessor
1262 is present.
1263
Christoph Lameterc1aee212007-05-31 00:40:47 -07001264 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1265 caches in the slab allocator. Saves per-node memory,
1266 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001267
Randy Dunlapa9913042005-10-23 12:57:11 -07001268 noalign [KNL,ARM]
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 noapic [SMP,APIC] Tells the kernel to not make use of any
1271 IOAPICs that may be present in the system.
1272
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 nobats [PPC] Do not use BATs for mapping kernel lowmem
1274 on "Classic" PPC cores.
1275
1276 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001277
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001278 nodelayacct [KNL] Disable per-task delay accounting
1279
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1281
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001282 noefi [X86-32,X86-64] Disable EFI runtime services support.
1283
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284 noexec [IA-64]
1285
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001286 noexec [X86-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 noexec=on: enable non-executable mappings (default)
1288 noexec=off: disable nn-executable mappings
1289
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001290 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001291 register save and restore. The kernel will only save
1292 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
Andi Kleen191679f2008-01-30 13:33:21 +01001294 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1295
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001297
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001298 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 instruction doesn't work correctly and not to
1300 use it.
1301
1302 nohalt [IA-64] Tells the kernel not to use the power saving
1303 function PAL_HALT_LIGHT when idle. This increases
1304 power-consumption. On the positive side, it reduces
1305 interrupt wake-up latency, which may improve performance
1306 in certain environments such as networked servers or
1307 real-time systems.
1308
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001309 nohz= [KNL] Boottime enable/disable dynamic ticks
1310 Valid arguments: on, off
1311 Default: on
1312
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001313 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
Zachary Amsden8542b202006-12-07 02:14:09 +01001314
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001315 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 disable unhandled interrupt sources.
1317
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001318 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001319 broken timer IRQ sources.
1320
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321 noisapnp [ISAPNP] Disables ISA PnP code.
1322
1323 noinitrd [RAM] Tells the kernel not to load any configured
1324 initial RAM disk.
1325
1326 nointroute [IA-64]
1327
Tony Luck0aa366f2007-07-20 11:22:30 -07001328 nojitter [IA64] Disables jitter checking for ITC timers.
1329
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001330 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001332 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001333
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 noltlbs [PPC] Do not use large page/tlb entries for kernel
1335 lowmem mapping on PPC40x.
1336
Horms312f1f02006-02-22 09:57:55 +09001337 nomca [IA-64] Disable machine check abort handling
1338
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001339 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001340
Andres Salomon83d73842007-10-12 23:04:06 +02001341 nomfgpt [X86-32] Disable Multi-Function General Purpose
1342 Timer usage (for AMD Geode machines).
1343
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001344 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001345
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001346 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001347 with UP alternatives
1348
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 noresidual [PPC] Don't use residual data on PReP machines.
1350
Randy Dunlapa9913042005-10-23 12:57:11 -07001351 noresume [SWSUSP] Disables resume and restores original swap
1352 space.
1353
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 no-scroll [VGA] Disables scrollback.
1355 This is required for the Braillex ib80-piezo Braille
1356 reader made by F.H. Papenmeier (Germany).
1357
1358 nosbagart [IA-64]
1359
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001360 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001361
Len Brown61ec7562007-08-16 03:34:22 -04001362 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1363 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364
Dave Jones97842212007-07-15 23:41:05 -07001365 nosoftlockup [KNL] Disable the soft-lockup detector.
1366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 nosync [HW,M68K] Disables sync negotiation for all devices.
1368
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001369 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370
1371 nousb [USB] Disable the USB subsystem
1372
1373 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001374
Fenghua Yua6c75b862008-03-14 13:57:08 -07001375 nptcg= [IA64] Override max number of concurrent global TLB
1376 purges which is reported from either PAL_VM_SUMMARY or
1377 SAL PALO.
1378
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001379 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1380 one of ['zone', 'node', 'default'] can be specified
1381 This can be set from sysctl after boot.
1382 See Documentation/sysctl/vm.txt for details.
1383
Dave Jonesa61c2d72006-01-07 23:18:19 +00001384 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 opl3= [HW,OSS]
1387 Format: <io>
1388
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 oprofile.timer= [HW]
1390 Use timer interrupt instead of performance counters
1391
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 osst= [HW,SCSI] SCSI Tape Driver
1393 Format: <buffer_size>,<write_threshold>
1394 See also Documentation/scsi/st.txt.
1395
1396 panic= [KNL] Kernel behaviour on panic
1397 Format: <timeout>
1398
1399 parkbd.port= [HW] Parallel port number the keyboard adapter is
1400 connected to, default is 0.
1401 Format: <parport#>
1402 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1403 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001404 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405
Randy Dunlapa9913042005-10-23 12:57:11 -07001406 parport= [HW,PPT] Specify parallel ports. 0 disables.
1407 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1408 Use 'auto' to force the driver to use any
1409 IRQ/DMA settings detected (the default is to
1410 ignore detected IRQ/DMA settings because of
1411 possible conflicts). You can specify the base
1412 address, IRQ, and DMA settings; IRQ and DMA
1413 should be numbers, or 'auto' (for using detected
1414 settings on that particular port), or 'nofifo'
1415 (to avoid using a FIFO even if it is detected).
1416 Parallel ports are assigned in the order they
1417 are specified on the command line, starting
1418 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419
Randy Dunlapa9913042005-10-23 12:57:11 -07001420 parport_init_mode= [HW,PPT]
1421 Configure VIA parallel port to operate in
1422 a specific mode. This is necessary on Pegasos
1423 computer where firmware has no options for setting
1424 up parallel port mode and sets it to spp.
1425 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426 Format: [spp|ps2|epp|ecp|ecpepp]
1427
Randy Dunlapa9913042005-10-23 12:57:11 -07001428 pas2= [HW,OSS] Format:
1429 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1430
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 pas16= [HW,SCSI]
1432 See header of drivers/scsi/pas16.c.
1433
Andrew Mortondd287792006-03-23 03:00:57 -08001434 pause_on_oops=
1435 Halt all CPUs after the first oops has been printed for
1436 the specified number of seconds. This is to be used if
1437 your oopses keep scrolling off the screen.
1438
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 pcbit= [HW,ISDN]
1440
1441 pcd. [PARIDE]
1442 See header of drivers/block/paride/pcd.c.
1443 See also Documentation/paride.txt.
1444
Randy Dunlapa9913042005-10-23 12:57:11 -07001445 pci=option[,option...] [PCI] various PCI subsystem options:
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001446 off [X86-32] don't probe for the PCI bus
1447 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001448 the hardware directly. Use this if your machine
1449 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001450 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001451 hardware access methods are allowed. Use this
1452 if you experience crashes upon bootup and you
1453 suspect they are caused by the BIOS.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001454 conf1 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001455 Mechanism 1.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001456 conf2 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001457 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001458 noaer [PCIE] If the PCIEAER kernel config parameter is
1459 enabled, this kernel boot option can be used to
1460 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001461 nodomains [PCI] Disable support for multiple PCI
1462 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001463 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001464 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001465 nomsi [MSI] If the PCI_MSI kernel config parameter is
1466 enabled, this kernel boot option can be used to
1467 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001468 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001469 routing table. These calls are known to be buggy
1470 on several machines and they hang the machine
1471 when used, but on other computers it's the only
1472 way to get the interrupt routing table. Try
1473 this option if the kernel is unable to allocate
1474 IRQs or discover secondary PCI buses on your
1475 motherboard.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001476 rom [X86-32] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001477 Use with caution as certain devices share
1478 address decoders between ROMs and other
1479 resources.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001480 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001481 assigned automatically to PCI devices. You can
1482 make the kernel exclude IRQs of your ISA cards
1483 this way.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001484 pirqaddr=0xAAAAA [X86-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001485 of the PIRQ table (normally generated
1486 by the BIOS) if it is outside the
1487 F0000h-100000h range.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001488 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001489 useful if the kernel is unable to find your
1490 secondary buses and you want to tell it
1491 explicitly which ones they are.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001492 assign-busses [X86-32] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001493 numbers ourselves, overriding
1494 whatever the firmware may have done.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001495 usepirqmask [X86-32] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001496 in the BIOS $PIR table. This is needed on
1497 some systems with broken BIOSes, notably
1498 some HP Pavilion N5400 and Omnibook XE3
1499 notebooks. This will have no effect if ACPI
1500 IRQ routing is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001501 noacpi [X86-32] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001502 or for PCI scanning.
Gary Hade62f420f2007-10-03 15:56:51 -07001503 use_crs [X86-32] Use _CRS for PCI resource
1504 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001505 routeirq Do IRQ routing for all PCI devices.
1506 This is normally done in pci_enable_device(),
1507 so this option is a temporary workaround
1508 for broken drivers that don't call it.
1509 firmware [ARM] Do not re-enumerate the bus but instead
1510 just use the configuration from the
1511 bootloader. This is currently used on
1512 IXP2000 systems where the bus has to be
1513 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001514 noearly [X86] Don't do any early type 1 scanning.
1515 This might help on some broken boards which
1516 machine check when some devices' config space
1517 is read. But various workarounds are disabled
1518 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001519 bfsort Sort PCI devices into breadth-first order.
1520 This sorting is done to get a device
1521 order compatible with older (<= 2.4) kernels.
1522 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001523 cbiosize=nn[KMG] The fixed amount of bus space which is
1524 reserved for the CardBus bridge's IO window.
1525 The default value is 256 bytes.
1526 cbmemsize=nn[KMG] The fixed amount of bus space which is
1527 reserved for the CardBus bridge's memory
1528 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001529
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530 pcmv= [HW,PCMCIA] BadgePAD 4
1531
1532 pd. [PARIDE]
1533 See Documentation/paride.txt.
1534
1535 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1536 boot time.
1537 Format: { 0 | 1 }
1538 See arch/parisc/kernel/pdc_chassis.c
1539
1540 pf. [PARIDE]
1541 See Documentation/paride.txt.
1542
1543 pg. [PARIDE]
1544 See Documentation/paride.txt.
1545
1546 pirq= [SMP,APIC] Manual mp-table setup
1547 See Documentation/i386/IO-APIC.txt.
1548
1549 plip= [PPT,NET] Parallel port network link
1550 Format: { parport<nr> | timid | 0 }
1551 See also Documentation/parport.txt.
1552
1553 pnpacpi= [ACPI]
1554 { off }
1555
1556 pnpbios= [ISAPNP]
1557 { on | off | curr | res | no-curr | no-res }
1558
1559 pnp_reserve_irq=
1560 [ISAPNP] Exclude IRQs for the autoconfiguration
1561
1562 pnp_reserve_dma=
1563 [ISAPNP] Exclude DMAs for the autoconfiguration
1564
1565 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001566 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567
1568 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001569 [ISAPNP] Exclude memory regions for the
1570 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 Ranges are in pairs (memory base and size).
1572
Ingo Molnar45807a12007-07-15 23:40:10 -07001573 print-fatal-signals=
1574 [KNL] debug: print fatal signals
1575 print-fatal-signals=1: print segfault info to
1576 the kernel console.
1577 default: off.
1578
Randy Dunlape84845c2007-07-15 23:40:25 -07001579 printk.time= Show timing data prefixed to each printk message line
1580 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1581
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001583 Format: [schedule,]<number>
1584 Param: "schedule" - profile schedule points.
1585 Param: <number> - step/bucket size as a power of 2 for
1586 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001587 Param: "sleep" - profile D-state sleeping (millisecs).
1588 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001589 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590
Randy Dunlapa9913042005-10-23 12:57:11 -07001591 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 Limit processor to maximum C-state
1593 max_cstate=9 overrides any DMI blacklist limit.
1594
Len Brown41c0d862005-12-28 12:43:51 -05001595 processor.nocst [HW,ACPI]
1596 Ignore the _CST method to determine C-states,
1597 instead using the legacy FADT method
1598
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1600 before loading.
1601 See Documentation/ramdisk.txt.
1602
Randy Dunlapa9913042005-10-23 12:57:11 -07001603 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1604 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1606 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001607 psmouse.resetafter= [HW,MOUSE]
1608 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 (0 = never).
1610 psmouse.resolution=
1611 [HW,MOUSE] Set desired mouse resolution, in dpi.
1612 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001613 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 0 = disabled, 1 = enabled (default).
1615
1616 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001617 Format:
1618 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001619
1620 pt. [PARIDE]
1621 See Documentation/paride.txt.
1622
Kay Sieversdc8c8582007-08-15 12:25:38 +02001623 pty.legacy_count=
1624 [KNL] Number of legacy pty's. Overwrites compiled-in
1625 default number.
1626
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001627 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001628
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 r128= [HW,DRM]
1630
1631 raid= [HW,RAID]
1632 See Documentation/md.txt.
1633
Randy Dunlapa9913042005-10-23 12:57:11 -07001634 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 See Documentation/ramdisk.txt.
1639
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001640 rcupdate.blimit= [KNL,BOOT]
1641 Set maximum number of finished RCU callbacks to process
1642 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001643
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001644 rcupdate.qhimark= [KNL,BOOT]
1645 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001646 RCU callbacks over which batch limiting is disabled.
1647
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001648 rcupdate.qlowmark= [KNL,BOOT]
1649 Set threshold of queued RCU callbacks below which
1650 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001651
Olof Johanssonffdfc402005-09-06 15:17:19 -07001652 rdinit= [KNL]
1653 Format: <full_path>
1654 Run specified binary instead of /init from the ramdisk,
1655 used for early userspace startup. See initrd.
1656
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001657 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001659 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660
1661 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1662
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001663 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001664 Format: nn[KMG]
1665 Reserves a hole at the top of the kernel virtual
1666 address space.
1667
Vivek Goyal7e962872006-09-27 01:50:44 -07001668 reset_devices [KNL] Force drivers to reset the underlying device
1669 during initialization.
1670
Randy Dunlapa9913042005-10-23 12:57:11 -07001671 resume= [SWSUSP]
1672 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001674 resume_offset= [SWSUSP]
1675 Specify the offset from the beginning of the partition
1676 given by "resume=" at which the swap header is located,
1677 in <PAGE_SIZE> units (needed only for swap files).
1678 See Documentation/power/swsusp-and-swap-files.txt
1679
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001680 retain_initrd [RAM] Keep initrd memory after extraction
1681
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 rhash_entries= [KNL,NET]
1683 Set number of hash buckets for route cache
1684
1685 riscom8= [HW,SERIAL]
1686 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1687
1688 ro [KNL] Mount root device read-only on boot
1689
1690 root= [KNL] Root filesystem
1691
1692 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1693 mount the root filesystem
1694
1695 rootflags= [KNL] Set root filesystem mount option string
1696
1697 rootfstype= [KNL] Set root filesystem type
1698
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001699 rootwait [KNL] Wait (indefinitely) for root device to show up.
1700 Useful for devices that are detected asynchronously
1701 (e.g. USB and MMC devices).
1702
James Morris20510f22007-10-16 23:31:32 -07001703 root_plug.vendor_id=
1704 [ROOTPLUG] Override the default vendor ID
1705
1706 root_plug.product_id=
1707 [ROOTPLUG] Override the default product ID
1708
1709 root_plug.debug=
1710 [ROOTPLUG] Enable debugging output
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 rw [KNL] Mount root device read-write on boot
1713
1714 S [KNL] Run init in single mode
1715
1716 sa1100ir [NET]
1717 See drivers/net/irda/sa1100_ir.c.
1718
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001720
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1722 Format: <io>[,<timeout>[,<isapnp>]]
1723
1724 scsi_debug_*= [SCSI]
1725 See drivers/scsi/scsi_debug.c.
1726
1727 scsi_default_dev_flags=
1728 [SCSI] SCSI default device flags
1729 Format: <integer>
1730
1731 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1732 Format: <vendor>:<model>:<flags>
1733 (flags are integer value)
1734
Randy Dunlap6af66322007-11-14 16:52:25 -08001735 scsi_logging_level= [SCSI] a bit mask of logging levels
1736 See drivers/scsi/scsi_logging.h for bits. Also
1737 settable via sysctl at dev.scsi.logging_level
1738 (/proc/sys/dev/scsi/logging_level).
1739 There is also a nice 'scsi_logging_level' script in the
1740 S390-tools package, available for download at
1741 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001743 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1744 discovered. async scans them in kernel threads,
1745 allowing boot to proceed. none ignores them, expecting
1746 user space to do the scan.
1747
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 selinux [SELINUX] Disable or enable SELinux at boot time.
1749 Format: { "0" | "1" }
1750 See security/selinux/Kconfig help text.
1751 0 -- disable.
1752 1 -- enable.
1753 Default value is set via kernel config option.
1754 If enabled at boot time, /selinux/disable can be used
1755 later to disable prior to initial policy load.
1756
James Morris4e5ab4c2006-06-09 00:33:33 -07001757 selinux_compat_net =
1758 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001759 Format: { "0" | "1" }
1760 0 -- use new secmark-based packet controls
1761 1 -- use legacy packet controls
1762 Default value is 0 (preferred).
1763 Value can be changed at runtime via
1764 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001765
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001766 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 shapers= [NET]
1769 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001770
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 sim710= [SCSI,HW]
1772 See header of drivers/scsi/sim710.c.
1773
1774 simeth= [IA-64]
1775 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001776
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 slram= [HW,MTD]
1778
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001779 slub_debug[=options[,slabs]] [MM, SLUB]
1780 Enabling slub_debug allows one to determine the
1781 culprit if slab objects become corrupted. Enabling
1782 slub_debug can create guard zones around objects and
1783 may poison objects when not in use. Also tracks the
1784 last alloc / free. For more information see
1785 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001786
1787 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001788 Determines the maximum allowed order for slabs.
1789 A high setting may cause OOMs due to memory
1790 fragmentation. For more information see
1791 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001792
1793 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001794 The minimum number of objects per slab. SLUB will
1795 increase the slab order up to slub_max_order to
1796 generate a sufficiently large slab able to contain
1797 the number of objects indicated. The higher the number
1798 of objects the smaller the overhead of tracking slabs
1799 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001800 For more information see Documentation/vm/slub.txt.
1801
1802 slub_min_order= [MM, SLUB]
1803 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001804 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001805 For more information see Documentation/vm/slub.txt.
1806
1807 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001808 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07001809 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001810 allocs to different slabs. Debug options disable
1811 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001812 For more information see Documentation/vm/slub.txt.
1813
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 smart2= [HW]
1815 Format: <io1>[,<io2>[,...,<io8>]]
1816
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001817 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001818 attempt to substitute SMP alternatives once at boot.
1819
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001820 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1821 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1822 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1823 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1824 smsc-ircc2.ircc_irq= [HW] IRQ line
1825 smsc-ircc2.ircc_dma= [HW] DMA channel
1826 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1827 0: Toshiba Satellite 1800 (GP data pin select)
1828 1: Fast pin select (default)
1829 2: ATC IRMode
1830
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 snd-ad1816a= [HW,ALSA]
1832
1833 snd-ad1848= [HW,ALSA]
1834
1835 snd-ali5451= [HW,ALSA]
1836
1837 snd-als100= [HW,ALSA]
1838
1839 snd-als4000= [HW,ALSA]
1840
1841 snd-azt2320= [HW,ALSA]
1842
1843 snd-cmi8330= [HW,ALSA]
1844
1845 snd-cmipci= [HW,ALSA]
1846
1847 snd-cs4231= [HW,ALSA]
1848
1849 snd-cs4232= [HW,ALSA]
1850
1851 snd-cs4236= [HW,ALSA]
1852
1853 snd-cs4281= [HW,ALSA]
1854
1855 snd-cs46xx= [HW,ALSA]
1856
1857 snd-dt019x= [HW,ALSA]
1858
1859 snd-dummy= [HW,ALSA]
1860
1861 snd-emu10k1= [HW,ALSA]
1862
1863 snd-ens1370= [HW,ALSA]
1864
1865 snd-ens1371= [HW,ALSA]
1866
1867 snd-es968= [HW,ALSA]
1868
1869 snd-es1688= [HW,ALSA]
1870
1871 snd-es18xx= [HW,ALSA]
1872
1873 snd-es1938= [HW,ALSA]
1874
1875 snd-es1968= [HW,ALSA]
1876
1877 snd-fm801= [HW,ALSA]
1878
1879 snd-gusclassic= [HW,ALSA]
1880
1881 snd-gusextreme= [HW,ALSA]
1882
1883 snd-gusmax= [HW,ALSA]
1884
1885 snd-hdsp= [HW,ALSA]
1886
1887 snd-ice1712= [HW,ALSA]
1888
1889 snd-intel8x0= [HW,ALSA]
1890
1891 snd-interwave= [HW,ALSA]
1892
1893 snd-interwave-stb=
1894 [HW,ALSA]
1895
1896 snd-korg1212= [HW,ALSA]
1897
1898 snd-maestro3= [HW,ALSA]
1899
1900 snd-mpu401= [HW,ALSA]
1901
1902 snd-mtpav= [HW,ALSA]
1903
1904 snd-nm256= [HW,ALSA]
1905
1906 snd-opl3sa2= [HW,ALSA]
1907
1908 snd-opti92x-ad1848=
1909 [HW,ALSA]
1910
1911 snd-opti92x-cs4231=
1912 [HW,ALSA]
1913
1914 snd-opti93x= [HW,ALSA]
1915
1916 snd-pmac= [HW,ALSA]
1917
1918 snd-rme32= [HW,ALSA]
1919
1920 snd-rme96= [HW,ALSA]
1921
1922 snd-rme9652= [HW,ALSA]
1923
1924 snd-sb8= [HW,ALSA]
1925
1926 snd-sb16= [HW,ALSA]
1927
1928 snd-sbawe= [HW,ALSA]
1929
1930 snd-serial= [HW,ALSA]
1931
1932 snd-sgalaxy= [HW,ALSA]
1933
1934 snd-sonicvibes= [HW,ALSA]
1935
1936 snd-sun-amd7930=
1937 [HW,ALSA]
1938
1939 snd-sun-cs4231= [HW,ALSA]
1940
1941 snd-trident= [HW,ALSA]
1942
1943 snd-usb-audio= [HW,ALSA,USB]
1944
1945 snd-via82xx= [HW,ALSA]
1946
1947 snd-virmidi= [HW,ALSA]
1948
1949 snd-wavefront= [HW,ALSA]
1950
1951 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001952
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1954 See Documentation/sonypi.txt
1955
1956 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1957 See Documentation/specialix.txt.
1958
1959 spia_io_base= [HW,MTD]
1960 spia_fio_base=
1961 spia_pedr=
1962 spia_peddr=
1963
1964 sscape= [HW,OSS]
1965 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001966
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1968 See Documentation/scsi/st.txt.
1969
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 sti= [PARISC,HW]
1971 Format: <num>
1972 Set the STI (builtin display/keyboard on the HP-PARISC
1973 machines) console (graphic card) which should be used
1974 as the initial boot-console.
1975 See also comment in drivers/video/console/sticore.c.
1976
1977 sti_font= [HW]
1978 See comment in drivers/video/console/sticore.c.
1979
1980 stifb= [HW]
1981 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1982
Greg Banks42a7fc42007-03-06 01:42:23 -08001983 sunrpc.pool_mode=
1984 [NFS]
1985 Control how the NFS server code allocates CPUs to
1986 service thread pools. Depending on how many NICs
1987 you have and where their interrupts are bound, this
1988 option will affect which CPUs will do NFS serving.
1989 Note: this parameter cannot be changed while the
1990 NFS server is running.
1991
1992 auto the server chooses an appropriate mode
1993 automatically using heuristics
1994 global a single global pool contains all CPUs
1995 percpu one pool for each CPU
1996 pernode one pool for each NUMA node (equivalent
1997 to global on non-NUMA machines)
1998
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002000
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 switches= [HW,M68k]
2002
2003 sym53c416= [HW,SCSI]
2004 See header of drivers/scsi/sym53c416.c.
2005
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002006 sysrq_always_enabled
2007 [KNL]
2008 Ignore sysrq setting - this boot parameter will
2009 neutralize any effect of /proc/sys/kernel/sysrq.
2010 Useful for debugging.
2011
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012 t128= [HW,SCSI]
2013 See header of drivers/scsi/t128.c.
2014
2015 tdfx= [HW,DRM]
2016
2017 thash_entries= [KNL,NET]
2018 Set number of hash buckets for TCP connection
2019
Len Brownf8707ec2007-08-12 00:12:54 -04002020 thermal.act= [HW,ACPI]
2021 -1: disable all active trip points in all thermal zones
2022 <degrees C>: override all lowest active trip points
2023
Len Brownc52a7412007-08-14 15:49:32 -04002024 thermal.crt= [HW,ACPI]
2025 -1: disable all critical trip points in all thermal zones
2026 <degrees C>: lower all critical trip points
2027
Len Brownf5487142007-08-12 00:12:44 -04002028 thermal.nocrt= [HW,ACPI]
2029 Set to disable actions on ACPI thermal zone
2030 critical and hot trip points.
2031
Len Brown72b33ef2007-08-12 00:12:17 -04002032 thermal.off= [HW,ACPI]
2033 1: disable ACPI thermal control
2034
Len Browna70cdc52007-08-12 00:12:35 -04002035 thermal.psv= [HW,ACPI]
2036 -1: disable all passive trip points
2037 <degrees C>: override all passive trip points to this value
2038
Len Brown730ff342007-08-12 00:12:26 -04002039 thermal.tzp= [HW,ACPI]
2040 Specify global default ACPI thermal zone polling rate
2041 <deci-seconds>: poll all this frequency
2042 0: no polling (default)
2043
Linus Torvalds1da177e2005-04-16 15:20:36 -07002044 tipar.timeout= [HW,PPT]
2045 Set communications timeout in tenths of a second
2046 (default 15).
2047
2048 tipar.delay= [HW,PPT]
2049 Set inter-bit delay in microseconds (default 10).
2050
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051 tmscsim= [HW,SCSI]
2052 See comment before function dc390_setup() in
2053 drivers/scsi/tmscsim.c.
2054
2055 tp720= [HW,PS2]
2056
2057 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002058 Format:
2059 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2060
Randy Dunlapa9913042005-10-23 12:57:11 -07002061 turbografx.map[2|3]= [HW,JOY]
2062 TurboGraFX parallel port interface
2063 Format:
2064 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065 See also Documentation/input/joystick-parport.txt
2066
2067 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2068 See header of drivers/scsi/u14-34f.c.
2069
2070 uart401= [HW,OSS]
2071 Format: <io>,<irq>
2072
2073 uart6850= [HW,OSS]
2074 Format: <io>,<irq>
2075
Alan Stern5f8364b2006-12-05 16:29:55 -05002076 uhci-hcd.ignore_oc=
2077 [USB] Ignore overcurrent events (default N).
2078 Some badly-designed motherboards generate lots of
2079 bogus events, for ports that aren't wired to
2080 anything. Set this parameter to avoid log spamming.
2081 Note that genuine overcurrent events won't be
2082 reported either.
2083
Alan Sternb5e795f2007-02-20 15:00:53 -05002084 usbcore.autosuspend=
2085 [USB] The autosuspend time delay (in seconds) used
2086 for newly-detected USB devices (default 2). This
2087 is the time required before an idle device will be
2088 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002089 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002090
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 usbhid.mousepoll=
2092 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002093
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002094 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002095 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002096 vdso=1: enable VDSO (default)
2097 vdso=0: disable VDSO mapping
2098
Roland McGrathaf65d642008-01-30 13:30:43 +01002099 vdso32= [X86-32,X86-64]
2100 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2101 vdso32=1: enable 32-bit VDSO (default)
2102 vdso32=0: disable 32-bit VDSO mapping
2103
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002104 vector= [IA-64,SMP]
2105 vector=percpu: enable percpu vector domain
2106
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 video= [FB] Frame buffer configuration
2108 See Documentation/fb/modedb.txt.
2109
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002110 vga= [BOOT,X86-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07002111 See Documentation/i386/boot.txt and
2112 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 Use vga=ask for menu.
2114 This is actually a boot loader parameter; the value is
2115 passed to the kernel using a special protocol.
2116
Randy Dunlapa9913042005-10-23 12:57:11 -07002117 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 size of <nn>. This can be used to increase the
2119 minimum size (128MB on x86). It can also be used to
2120 decrease the size and leave more room for directly
2121 mapped kernel RAM.
2122
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002123 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2124 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002126 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2127 Format: <command>
2128
2129 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2130 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002131
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132 waveartist= [HW,OSS]
2133 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002134
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135 wd33c93= [HW,SCSI]
2136 See header of drivers/scsi/wd33c93.c.
2137
2138 wd7000= [HW,SCSI]
2139 See header of drivers/scsi/wd7000.c.
2140
2141 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002142 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
2144 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2145 xd_geo= See header of drivers/block/xd.c.
2146
2147 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002148 Format:
2149 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150
Andi Kleena62eaf12006-02-16 23:41:58 +01002151 norandmaps Don't use address space randomization
2152 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2153
Randy Dunlapa9913042005-10-23 12:57:11 -07002154______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155
2156TODO:
2157
2158 Add documentation for ALSA options.
2159 Add more DRM drivers.