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Stefan Richter0ee9d712006-04-01 01:42:29 +02001 Kernel Parameters
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 ~~~~~~~~~~~~~~~~~
3
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.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070038 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070047 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070051 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070060 MSI Message Signaled Interrupts (PCI).
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070064 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PARIDE The ParIDE subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
79 Documentation/scsi/.
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090082 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 SMP The kernel is an SMP kernel.
84 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070085 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 TS Appropriate touchscreen support is enabled.
87 USB USB support is enabled.
88 USBHID USB Human Interface Device support is enabled.
89 V4L Video For Linux support is enabled.
90 VGA The VGA console has been enabled.
91 VT Virtual terminal support is enabled.
92 WDT Watchdog support is enabled.
93 XT IBM PC/XT MFM hard disk support is enabled.
94 X86-64 X86-64 architecture is enabled.
95 More X86-64 boot options can be found in
96 Documentation/x86_64/boot-options.txt .
97
98In addition, the following text indicates that the option:
99
100 BUGS= Relates to possible processor bugs on the said processor.
101 KNL Is a kernel start-up parameter.
102 BOOT Is a boot loader parameter.
103
104Parameters denoted with BOOT are actually interpreted by the boot
105loader, and have no meaning to the kernel directly.
106Do not modify the syntax of boot loader parameters without extreme
107need or coordination with <Documentation/i386/boot.txt>.
108
Karsten Weiss55588702007-02-13 13:26:21 +0100109There are also arch-specific kernel-parameters not documented here.
110See for example <Documentation/x86_64/boot-options.txt>.
111
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
113a trailing = on the name of any parameter states that that parameter will
114be entered as an environment variable, whereas its absence indicates that
115it will appear as a kernel argument readable via /proc/cmdline by programs
116running once the system is up.
117
jens m. noedler9c4751f2006-09-29 02:00:27 -0700118The number of kernel parameters is not limited, but the length of the
119complete command line (parameters including spaces etc.) is limited to
120a fixed number of characters. This limit depends on the architecture
121and is between 256 and 4096 characters. It is defined in the file
122./include/asm/setup.h as COMMAND_LINE_SIZE.
123
124
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 53c7xx= [HW,SCSI] Amiga SCSI controllers
126 See header of drivers/scsi/53c7xx.c.
127 See also Documentation/scsi/ncr53c7xx.txt.
128
Bernhard Walle03d926f2007-03-06 02:29:44 -0800129 acpi= [HW,ACPI,X86-64,i386]
130 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700131 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 force -- enable ACPI if default was off
133 off -- disable ACPI if default was on
134 noirq -- do not use ACPI for IRQ routing
135 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700136 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 strictly ACPI specification compliant.
138
139 See also Documentation/pm.txt, pci=noacpi
140
Len Browna1fdcc02007-03-11 03:26:14 -0400141 acpi_apic_instance= [ACPI, IOAPIC]
142 Format: <int>
143 2: use 2nd APIC table, if available
144 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400145 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400146
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 acpi_sleep= [HW,ACPI] Sleep options
148 Format: { s3_bios, s3_mode }
149 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700150
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700152 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
Randy Dunlapa9913042005-10-23 12:57:11 -0700154 acpi_irq_balance [HW,ACPI]
155 ACPI will balance active IRQs
156 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Randy Dunlapa9913042005-10-23 12:57:11 -0700158 acpi_irq_nobalance [HW,ACPI]
159 ACPI will not move active IRQs (default)
160 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Randy Dunlapa9913042005-10-23 12:57:11 -0700162 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
163 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 Format: <irq>,<irq>...
165
Randy Dunlapa9913042005-10-23 12:57:11 -0700166 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 Format: <irq>,<irq>...
168
Len Browna1f9e652006-01-25 23:47:36 -0500169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
170 Format: To spoof as Windows 98: ="Microsoft Windows"
171
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 acpi_osi= [HW,ACPI] empty param disables _OSI
173
174 acpi_serialize [HW,ACPI] force serialization of AML methods
175
176 acpi_skip_timer_override [HW,ACPI]
177 Recognize and ignore IRQ0/pin2 Interrupt Override.
178 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100179 acpi_use_timer_override [HW,ACPI}
180 Use timer override. For some broken Nvidia NF5 boards
181 that require a timer override, but don't have
182 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Zhang Ruif9891062007-04-24 13:53:22 +0800184 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700186 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 1: enable, 0: disable. It is useful for boot time
188 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800189 via /sys/module/acpi/parameters/debug_layer.
190 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
191 Available bits (add the numbers together) to enable debug output
192 for specific parts of the ACPI subsystem:
193 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
194 0x10 namespace 0x20 parser 0x40 dispatcher
195 0x80 executer 0x100 resources 0x200 acpica debugger
196 0x400 os services 0x800 acpica disassembler.
197 The number can be in decimal or prefixed with 0x in hex.
198 Warning: Many of these options can produce a lot of
199 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Zhang Ruif9891062007-04-24 13:53:22 +0800201 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700203 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800206 via /sys/module/acpi/parameters/debug_level.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable different
209 debug output levels of the ACPI subsystem:
210 0x01 error 0x02 warn 0x04 init 0x08 debug object
211 0x10 info 0x20 init names 0x40 parse 0x80 load
212 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
213 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
214 0x10000 resources 0x20000 user requests 0x40000 package.
215 The number can be in decimal or prefixed with 0x in hex.
216 Warning: Many of these options can produce a lot of
217 output and make your system unusable. Be very careful.
218
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
220 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
221
Luming Yu30e332f2005-08-12 00:31:00 -0400222 acpi_generic_hotkey [HW,ACPI]
223 Allow consolidated generic hotkey driver to
Randy Dunlapa9913042005-10-23 12:57:11 -0700224 override platform specific driver.
Luming Yu30e332f2005-08-12 00:31:00 -0400225 See also Documentation/acpi-hotkey.txt.
226
john stultz5d0cf412006-06-26 00:25:12 -0700227 acpi_pm_good [IA-32,X86-64]
228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
231
Chuck Ebbert66759a02005-09-12 18:49:25 +0200232 enable_timer_pin_1 [i386,x86-64]
233 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700234 Can be useful to work around chipset bugs
235 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200236 The kernel tries to set a reasonable default.
237
238 disable_timer_pin_1 [i386,x86-64]
239 Disable PIN 1 of APIC timer
240 Can be useful to work around chipset bugs.
241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 ad1816= [HW,OSS]
243 Format: <io>,<irq>,<dma>,<dma2>
244 See also Documentation/sound/oss/AD1816.
245
246 ad1848= [HW,OSS]
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
248
249 adlib= [HW,OSS]
250 Format: <io>
Randy Dunlapa9913042005-10-23 12:57:11 -0700251
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 Dunlapa9913042005-10-23 12:57:11 -0700291 apic= [APIC,i386] Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 Format: { quiet (default) | verbose | debug }
293 Change the amount of debugging information output
294 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700295
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 apm= [APM] Advanced Power Management
297 See header of arch/i386/kernel/apm.c.
298
299 applicom= [HW]
300 Format: <mem>,<irq>
Randy Dunlapa9913042005-10-23 12:57:11 -0700301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
303 Format: <io>,<irq>,<nodeID>
304
305 ataflop= [HW,M68k]
306
307 atarimouse= [HW,MOUSE] Atari Mouse
308
309 atascsi= [HW,SCSI] Atari SCSI
310
311 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
312 EzKey and similar keyboards
313
314 atkbd.reset= [HW] Reset keyboard during initialization
315
Randy Dunlapa9913042005-10-23 12:57:11 -0700316 atkbd.set= [HW] Select keyboard code set
317 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318
319 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
320 keyboards
321
322 atkbd.softraw= [HW] Choose between synthetic and real raw mode
323 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700324
325 atkbd.softrepeat= [HW]
326 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327
328 autotest [IA64]
329
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 aztcd= [HW,CD] Aztech CD268 CDROM driver
331 Format: <io>,0x79 (?)
332
333 baycom_epp= [HW,AX25]
334 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
337 Format: <io>,<mode>
338 See header of drivers/net/hamradio/baycom_par.c.
339
Randy Dunlapa9913042005-10-23 12:57:11 -0700340 baycom_ser_fdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 Format: <io>,<irq>,<mode>[,<baud>]
343 See header of drivers/net/hamradio/baycom_ser_fdx.c.
344
Randy Dunlapa9913042005-10-23 12:57:11 -0700345 baycom_ser_hdx= [HW,AX25]
346 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 Format: <io>,<irq>,<mode>
348 See header of drivers/net/hamradio/baycom_ser_hdx.c.
349
350 blkmtd_device= [HW,MTD]
351 blkmtd_erasesz=
352 blkmtd_ro=
353 blkmtd_bs=
354 blkmtd_count=
355
356 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700357 bttv.radio= Most important insmod options are available as
358 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
360 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
361
362 BusLogic= [HW,SCSI]
363 See drivers/scsi/BusLogic.c, comment before function
364 BusLogic_ParseDriverOptions().
365
366 c101= [NET] Moxa C101 synchronous serial card
367
368 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
369 Sometimes CPU hardware bugs make them report the cache
370 size incorrectly. The kernel will attempt work arounds
371 to fix known problems, but for some CPUs it is not
372 possible to determine what the correct size should be.
373 This option provides an override for these situations.
374
375 cdu31a= [HW,CD]
376 Format: <io>,<irq>[,PAS]
377 See header of drivers/cdrom/cdu31a.c.
378
379 chandev= [HW,NET] Generic channel device initialisation
380
381 checkreqprot [SELINUX] Set initial checkreqprot flag value.
382 Format: { "0" | "1" }
383 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700384 0 -- check protection applied by kernel (includes
385 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 1 -- check protection requested by application.
387 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700388 Value can be changed at runtime via
389 /selinux/checkreqprot.
390
john stultz734efb42006-06-26 00:25:05 -0700391 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
392 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200393 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700394 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200395 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 Format: { pit | tsc | cyclone | pmtmr }
397
Chuck Ebbert86c41832007-02-13 13:26:25 +0100398 code_bytes [IA32] How many bytes of object code to print in an
399 oops report.
400 Range: 0 - 8192
401 Default: 64
402
Andi Kleenf9262c12006-03-08 17:57:25 -0800403 disable_8254_timer
404 enable_8254_timer
405 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
406 over the 8254 in addition to over the IO-APIC. The
407 kernel tries to set a sensible default.
408
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 hpet= [IA-32,HPET] option to disable HPET and use PIT.
410 Format: disable
411
412 cm206= [HW,CD]
413 Format: { auto | [<io>,][<irq>] }
414
415 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700416 Format:
417 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
419 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
420 Format: <io>[,<irq>]
421
Randy Dunlapa9913042005-10-23 12:57:11 -0700422 com90xx= [HW,NET]
423 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 Format: <io>[,<irq>[,<memstart>]]
425
426 condev= [HW,S390] console device
427 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700428
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 console= [KNL] Output console device and options.
430
431 tty<n> Use the virtual console device <n>.
432
433 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800434 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800436 the form "bbbbpnf", where "bbbb" is the baud rate,
437 "p" is parity ("n", "o", or "e"), "n" is number of
438 bits, and "f" is flow control ("r" for RTS or
439 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800441 See Documentation/serial-console.txt for more
442 information. See
443 Documentation/networking/netconsole.txt for an
444 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445
446 uart,io,<addr>[,options]
447 uart,mmio,<addr>[,options]
448 Start an early, polled-mode console on the 8250/16550
449 UART at the specified I/O port or MMIO address,
450 switching to the matching ttyS device later. The
451 options are the same as for ttyS, above.
452
453 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700454 Format:
455 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456
457 cpia_pp= [HW,PPT]
458 Format: { parport<nr> | auto | none }
459
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700460 crashkernel=nn[KMG]@ss[KMG]
461 [KNL] Reserve a chunk of physical memory to
462 hold a kernel to switch to with kexec on panic.
463
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 cs4232= [HW,OSS]
465 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
466
467 cs89x0_dma= [HW,NET]
468 Format: <dma>
469
470 cs89x0_media= [HW,NET]
471 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700472
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
Randy Dunlapa9913042005-10-23 12:57:11 -0700474
475 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 See header of drivers/s390/block/dasd_devmap.c.
477
478 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
479 (one device per port)
480 Format: <port#>,<type>
481 See also Documentation/input/joystick-parport.txt
482
483 debug [KNL] Enable kernel debugging (events log level).
484
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700485 debug_locks_verbose=
486 [KNL] verbose self-tests
487 Format=<0|1>
488 Print debugging info while doing the locking API
489 self-tests.
490 We default to 0 (no extra messages), setting it to
491 1 will print _a lot_ more information - normally
492 only useful to kernel developers.
493
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 decnet= [HW,NET]
495 Format: <area>[,<node>]
496 See also Documentation/networking/decnet.txt.
497
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 dhash_entries= [KNL]
499 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700500
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 digi= [HW,SERIAL]
502 IO parameters + enable/disable command.
503
504 digiepca= [HW,SERIAL]
505 See drivers/char/README.epca and
506 Documentation/digiepca.txt.
507
508 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
509 support available.
510 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
511
512 dmasound= [HW,OSS] Sound subsystem buffers
513
514 dscc4.setup= [NET]
515
516 dtc3181e= [HW,SCSI]
517
Paul Mundte523d932007-02-28 18:30:01 +0900518 earlyprintk= [IA-32,X86-64,SH]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 earlyprintk=vga
520 earlyprintk=serial[,ttySn[,baudrate]]
521
Randy Dunlapa9913042005-10-23 12:57:11 -0700522 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 takes over.
524
525 Only vga or serial at a time, not both.
526
527 Currently only ttyS0 and ttyS1 are supported.
528
529 Interaction with the standard serial driver is not
530 very good.
531
532 The VGA output is eventually overwritten by the real
533 console.
534
535 eata= [HW,SCSI]
536
Len Brown53f11d42005-12-05 16:46:36 -0500537 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
538 Format: <int>
539 0: polling mode
540 non-0: interrupt mode (default)
541
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 eda= [HW,PS2]
543
544 edb= [HW,PS2]
545
546 edd= [EDD]
547 Format: {"of[f]" | "sk[ipmbr]"}
548 See comment in arch/i386/boot/edd.S
549
Randy Dunlapa9913042005-10-23 12:57:11 -0700550 eicon= [HW,ISDN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 Format: <id>,<membase>,<irq>
552
553 eisa_irq_edge= [PARISC,HW]
554 See header of drivers/parisc/eisa.c.
555
556 elanfreq= [IA-32]
557 See comment before function elanfreq_setup() in
558 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
559
560 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800561 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700562 See Documentation/block/as-iosched.txt and
563 Documentation/block/deadline-iosched.txt for details.
564
Vivek Goyalaac04b32006-01-09 20:51:47 -0800565 elfcorehdr= [IA-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700566 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800567 image elf header. Generally kexec loader will
568 pass this option to capture kernel.
569 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
571 enforcing [SELINUX] Set initial enforcing status.
572 Format: {"0" | "1"}
573 See security/selinux/Kconfig help text.
574 0 -- permissive (log only, no denials).
575 1 -- enforcing (deny and log).
576 Default value is 0.
577 Value can be changed at runtime via /selinux/enforce.
578
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 es1371= [HW,OSS]
580 Format: <spdif>,[<nomix>,[<amplifier>]]
581 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700582
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 ether= [HW,NET] Ethernet cards parameters
584 This option is obsoleted by the "netdev=" option, which
585 has equivalent usage. See its documentation for details.
586
587 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
588 Format: <io>[,<irq>]
589
Akinobu Mitade1ba092006-12-08 02:39:42 -0800590 failslab=
591 fail_page_alloc=
592 fail_make_request=[KNL]
593 General fault injection mechanism.
594 Format: <interval>,<probability>,<space>,<times>
595 See also /Documentation/fault-injection/.
596
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 fd_mcs= [HW,SCSI]
598 See header of drivers/scsi/fd_mcs.c.
599
600 fdomain= [HW,SCSI]
601 See header of drivers/scsi/fdomain.c.
602
603 floppy= [HW]
604 See Documentation/floppy.txt.
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 gamecon.map[2|3]=
607 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
608 support via parallel port (up to 5 devices per port)
609 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
610 See also Documentation/input/joystick-parport.txt
611
612 gamma= [HW,DRM]
613
614 gdth= [HW,SCSI]
615 See header of drivers/scsi/gdth.c.
616
617 gpt [EFI] Forces disk with valid GPT signature but
618 invalid Protective MBR to be treated as GPT.
619
620 gscd= [HW,CD]
621 Format: <io>
622
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 gvp11= [HW,SCSI]
624
625 hashdist= [KNL,NUMA] Large hashes allocated during boot
626 are distributed across NUMA nodes. Defaults on
627 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700628 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629
630 hcl= [IA-64] SGI's Hardware Graph compatibility layer
631
632 hd= [EIDE] (E)IDE hard drive subsystem geometry
633 Format: <cyl>,<head>,<sect>
634
635 hd?= [HW] (E)IDE subsystem
636 hd?lun= See Documentation/ide.txt.
637
638 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
639 size of <nn>. This works even on boxes that have no
640 highmem otherwise. This also works to reduce highmem
641 size on bigger boxes.
642
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800643 highres= [KNL] Enable/disable high resolution timer mode.
644 Valid parameters: "on", "off"
645 Default: "on"
646
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 hisax= [HW,ISDN]
648 See Documentation/isdn/README.HiSax.
649
650 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
651
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200653 i8042.dumbkbd [HW] Pretend that controller can only read data from
654 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 (Don't attempt to blink the leds)
656 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500657 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 i8042.nomux [HW] Don't check presence of an active multiplexing
659 controller
660 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
661 controllers
662 i8042.panicblink=
663 [HW] Frequency with which keyboard LEDs should blink
664 when kernel panics (default is 0.5 sec)
665 i8042.reset [HW] Reset the controller during init and cleanup
666 i8042.unlock [HW] Unlock (ignore) the keylock
667
668 i810= [HW,DRM]
669
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700670 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
671 indicates that the driver is running on unsupported
672 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
674 does not match list of supported models.
675 i8k.power_status
676 [HW] Report power status in /proc/i8k
677 (disabled by default)
678 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
679 capability is set.
680
681 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
682 See Documentation/mca.txt.
683
684 icn= [HW,ISDN]
685 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
686
687 ide= [HW] (E)IDE subsystem
688 Format: ide=nodma or ide=doubler or ide=reverse
689 See Documentation/ide.txt.
690
691 ide?= [HW] (E)IDE subsystem
692 Format: ide?=noprobe or chipset specific parameters.
693 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
696 See Documentation/ide.txt.
697
698 idle= [HW]
699 Format: idle=poll or idle=halt
Randy Dunlapa9913042005-10-23 12:57:11 -0700700
Ingo Molnar792908222006-12-06 20:40:51 -0800701 ignore_loglevel [KNL]
702 Ignore loglevel setting - this will print /all/
703 kernel messages to the console. Useful for debugging.
704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 ihash_entries= [KNL]
706 Set number of hash buckets for inode cache.
707
708 in2000= [HW,SCSI]
709 See header of drivers/scsi/in2000.c.
710
711 init= [KNL]
712 Format: <full_path>
713 Run specified binary instead of /sbin/init as init
714 process.
715
716 initcall_debug [KNL] Trace initcalls as they are executed. Useful
717 for working out where the kernel is dying during
718 startup.
719
720 initrd= [BOOT] Specify the location of the initial ramdisk
721
722 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
723 Format: <irq>
724
Jesse Barnes2bd0fa32005-12-13 03:05:03 -0500725 combined_mode= [HW] control which driver uses IDE ports in combined
726 mode: legacy IDE driver, libata, or both
727 (in the libata case, libata.atapi_enabled=1 may be
728 useful as well). Note that using the ide or libata
729 options may affect your device naming (e.g. by
730 changing hdc to sdb).
731 Format: combined (default), ide, or libata
732
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 inttest= [IA64]
734
735 io7= [HW] IO7 for Marvel based alpha systems
736 See comment before marvel_specify_io7 in
737 arch/alpha/kernel/core_marvel.c.
738
739 ip= [IP_PNP]
740 See Documentation/nfsroot.txt.
741
742 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
743 See comment before ip2_setup() in drivers/char/ip2.c.
744
745 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
746 See header of drivers/scsi/ips.c.
747
Simon Horman72c4a132006-09-13 19:57:18 -0700748 ports= [IP_VS_FTP] IPVS ftp helper module
749 Default is 21.
750 Up to 8 (IP_VS_APP_MAX_PORTS) ports
751 may be specified.
752 Format: <port>,<port>....
753
Alan Cox200803d2005-06-28 20:45:18 -0700754 irqfixup [HW]
755 When an interrupt is not handled search all handlers
756 for it. Intended to get systems with badly broken
757 firmware running.
758
759 irqpoll [HW]
760 When an interrupt is not handled search all handlers
761 for it. Also check all handlers each timer
762 interrupt. Intended to get systems with badly broken
763 firmware running.
764
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700766 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767
768 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800769 Format:
770 <cpu number>,...,<cpu number>
771 or
772 <cpu number>-<cpu number> (must be a positive range in ascending order)
773 or a mixture
774 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 This option can be used to specify one or more CPUs
776 to isolate from the general SMP balancing and scheduling
777 algorithms. The only way to move a process onto or off
778 an "isolated" CPU is via the CPU affinity syscalls.
779 <cpu number> begins at 0 and the maximum value is
780 "number of CPUs in system - 1".
781
782 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700783 alternative -- manually setting the CPU mask of all
784 tasks in the system -- can cause problems and
785 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
787 isp16= [HW,CD]
788 Format: <io>,<irq>,<dma>,<setup>
789
Randy Dunlapa9913042005-10-23 12:57:11 -0700790 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791
792 js= [HW,JOY] Analog joystick
793 See Documentation/input/joystick.txt.
794
795 keepinitrd [HW,ARM]
796
Randy Dunlapa9913042005-10-23 12:57:11 -0700797 kstack=N [IA-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 in oops dumps.
799
800 l2cr= [PPC]
801
Randy Dunlapa9913042005-10-23 12:57:11 -0700802 lapic [IA-32,APIC] Enable the local APIC even if BIOS
803 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
Linus Torvalds2e7c2832007-03-23 11:32:31 -0700805 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +0100806 C2 power state.
807
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
809 Format: addr:<io>,irq:<irq>
810
Randy Dunlapa9913042005-10-23 12:57:11 -0700811 llsc*= [IA64] See function print_params() in
812 arch/ia64/sn/kernel/llsc4.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813
814 load_ramdisk= [RAM] List of ramdisks to load from floppy
815 See Documentation/ramdisk.txt.
816
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800817 lockd.nlm_grace_period=P [NFS] Assign grace period.
818 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800820 lockd.nlm_tcpport=N [NFS] Assign TCP port.
821 Format: <integer>
822
823 lockd.nlm_timeout=T [NFS] Assign timeout value.
824 Format: <integer>
825
826 lockd.nlm_udpport=M [NFS] Assign UDP port.
827 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828
829 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
830 Format: <irq>
831
832 loglevel= All Kernel Messages with a loglevel smaller than the
833 console loglevel will be printed to the console. It can
834 also be changed with klogd or other programs. The
835 loglevels are defined as follows:
836
837 0 (KERN_EMERG) system is unusable
838 1 (KERN_ALERT) action must be taken immediately
839 2 (KERN_CRIT) critical conditions
840 3 (KERN_ERR) error conditions
841 4 (KERN_WARNING) warning conditions
842 5 (KERN_NOTICE) normal but significant condition
843 6 (KERN_INFO) informational
844 7 (KERN_DEBUG) debug-level messages
845
846 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700847 Format: { n | nk | nM }
848 n must be a power of two. The default size
849 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
851 lp=0 [LP] Specify parallel ports to use, e.g,
852 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
853 lp=reset first parallel port). 'lp=0' disables the
854 lp=auto printer driver. 'lp=reset' (which can be
855 specified in addition to the ports) causes
856 attached printers to be reset. Using
857 lp=port1,port2,... specifies the parallel ports
858 to associate lp devices with, starting with
859 lp0. A port specification may be 'none' to skip
860 that lp device, or a parport name such as
861 'parport0'. Specifying 'lp=auto' instead of a
862 port specification list means that device IDs
863 from each port should be examined, to see if
864 an IEEE 1284-compliant printer is attached; if
865 so, the driver will manage that printer.
866 See also header of drivers/char/lp.c.
867
868 lpj=n [KNL]
869 Sets loops_per_jiffy to given constant, thus avoiding
870 time-consuming boot-time autodetection (up to 250 ms per
871 CPU). 0 enables autodetection (default). To determine
872 the correct value for your kernel, boot with normal
873 autodetection and see what value is printed. Note that
874 on SMP systems the preset will be applied to all CPUs,
875 which is likely to cause problems if your CPUs need
876 significantly divergent settings. An incorrect value
877 will cause delays in the kernel to be wrong, leading to
878 unpredictable I/O errors and other breakage. Although
879 unlikely, in the extreme case this might damage your
880 hardware.
881
882 ltpc= [NET]
883 Format: <io>,<irq>,<dma>
884
Randy Dunlapa9913042005-10-23 12:57:11 -0700885 mac5380= [HW,SCSI] Format:
886 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887
Randy Dunlapa9913042005-10-23 12:57:11 -0700888 mac53c9x= [HW,SCSI] Format:
889 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890
Randy Dunlapa9913042005-10-23 12:57:11 -0700891 machvec= [IA64] Force the use of a particular machine-vector
892 (machvec) in a generic kernel.
893 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894
Randy Dunlapa9913042005-10-23 12:57:11 -0700895 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 be mounted
897 Format: <1-256>
898
899 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Randy Dunlap78f92a82007-02-17 19:58:30 +0100900 should make use of.
901 Using "nosmp" or "maxcpus=0" will disable SMP
902 entirely (the MPS table probe still happens, though).
903 A command-line option of "maxcpus=<NUM>", where <NUM>
904 is an integer greater than 0, limits the maximum number
905 of CPUs activated in SMP mode to <NUM>.
906 Using "maxcpus=1" on an SMP kernel is the trivial
907 case of an SMP kernel with only one CPU.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908
Bob Picco2b2c3752005-06-29 18:00:00 -0700909 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
910 equal to this physical address is ignored.
911
Randy Dunlapa9913042005-10-23 12:57:11 -0700912 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 Should be between 1 and 2^32-1.
914
915 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -0700916 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 Should be between 1 and 16384.
918
919 mca-pentium [BUGS=IA-32]
920
921 mcatest= [IA-64]
922
923 mcd= [HW,CD]
924 Format: <port>,<irq>,<mitsumi_bug_93_wait>
925
926 mcdx= [HW,CD]
927
928 mce [IA-32] Machine Check Exception
929
930 md= [HW] RAID subsystems devices and level
931 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700932
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 mdacon= [MDA]
934 Format: <first>,<last>
935 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -0700936
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
938 Amount of memory to be used when the kernel is not able
939 to see the whole system memory or for test.
940 [IA-32] Use together with memmap= to avoid physical
941 address space collisions. Without memmap= PCI devices
942 could be placed at addresses belonging to unused RAM.
943
944 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
945 memory.
946
akpm@osdl.org69cda7b2006-01-09 20:51:46 -0800947 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 E820 memory map, as specified by the user.
949 Such memmap=exactmap lines can be constructed based on
950 BIOS output or other requirements. See the memmap=nn@ss
951 option description.
952
953 memmap=nn[KMG]@ss[KMG]
954 [KNL] Force usage of a specific region of memory
955 Region of memory to be used, from ss to ss+nn.
956
957 memmap=nn[KMG]#ss[KMG]
958 [KNL,ACPI] Mark specific memory as ACPI data.
959 Region of memory to be used, from ss to ss+nn.
960
961 memmap=nn[KMG]$ss[KMG]
962 [KNL,ACPI] Mark specific memory as reserved.
963 Region of memory to be used, from ss to ss+nn.
964
965 meye.*= [HW] Set MotionEye Camera parameters
966 See Documentation/video4linux/meye.txt.
967
968 mga= [HW,DRM]
969
akpm@osdl.org198e2f12006-01-12 01:05:30 -0800970 migration_cost=
971 [KNL,SMP] debug: override scheduler migration costs
972 Format: <level-1-usecs>,<level-2-usecs>,...
973 This debugging option can be used to override the
974 default scheduler migration cost matrix. The numbers
975 are indexed by 'CPU domain distance'.
976 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
977 box will set up an intra-core migration cost of
978 1 msec, an inter-core migration cost of 2 msecs,
979 and an inter-node migration cost of 3 msecs.
980
981 WARNING: using the wrong values here can break
982 scheduler performance, so it's only for scheduler
983 development purposes, not production environments.
984
985 migration_debug=
986 [KNL,SMP] migration cost auto-detect verbosity
987 Format=<0|1|2>
988 If a system's migration matrix reported at bootup
989 seems erroneous then this option can be used to
990 increase verbosity of the detection process.
991 We default to 0 (no extra messages), 1 will print
992 some more information, and 2 will be really
993 verbose (probably only useful if you also have a
994 serial console attached to the system).
995
996 migration_factor=
997 [KNL,SMP] multiply/divide migration costs by a factor
998 Format=<percent>
999 This debug option can be used to proportionally
1000 increase or decrease the auto-detected migration
1001 costs for all entries of the migration matrix.
1002 E.g. migration_factor=150 will increase migration
1003 costs by 50%. (and thus the scheduler will be less
1004 eager migrating cache-hot tasks)
1005 migration_factor=80 will decrease migration costs
1006 by 20%. (thus the scheduler will be more eager to
1007 migrate tasks)
1008
1009 WARNING: using the wrong values here can break
1010 scheduler performance, so it's only for scheduler
1011 development purposes, not production environments.
1012
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 mousedev.tap_time=
1014 [MOUSE] Maximum time between finger touching and
1015 leaving touchpad surface for touch to be considered
1016 a tap and be reported as a left button click (for
1017 touchpads working in absolute mode only).
1018 Format: <msecs>
1019 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1020 reporting absolute coordinates, such as tablets
1021 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1022 reporting absolute coordinates, such as tablets
1023
1024 mpu401= [HW,OSS]
1025 Format: <io>,<irq>
1026
1027 MTD_Partition= [MTD]
1028 Format: <name>,<region-number>,<size>,<offset>
1029
Randy Dunlapa9913042005-10-23 12:57:11 -07001030 MTD_Region= [MTD] Format:
1031 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032
1033 mtdparts= [MTD]
1034 See drivers/mtd/cmdline.c.
1035
1036 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001037 [HW] Make the MicroTouch USB driver use raw coordinates
1038 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039
1040 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1041
1042 NCR_D700= [HW,SCSI]
1043 See header of drivers/scsi/NCR_D700.c.
1044
1045 ncr5380= [HW,SCSI]
1046
1047 ncr53c400= [HW,SCSI]
1048
1049 ncr53c400a= [HW,SCSI]
1050
1051 ncr53c406a= [HW,SCSI]
1052
1053 ncr53c8xx= [HW,SCSI]
1054
1055 netdev= [NET] Network devices parameters
1056 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1057 Note that mem_start is often overloaded to mean
1058 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001059 This usage is only documented in each driver source
1060 file if at all.
1061
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 nfsaddrs= [NFS]
1063 See Documentation/nfsroot.txt.
1064
1065 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1066 See Documentation/nfsroot.txt.
1067
Trond Myklebusta72b4422006-01-03 09:55:41 +01001068 nfs.callback_tcpport=
1069 [NFS] set the TCP port on which the NFSv4 callback
1070 channel should listen.
1071
Trond Myklebust58df0952006-01-03 09:55:57 +01001072 nfs.idmap_cache_timeout=
1073 [NFS] set the maximum lifetime for idmapper cache
1074 entries.
1075
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1077
1078 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1079 emulation library even if a 387 maths coprocessor
1080 is present.
1081
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -07001082 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1083 when set.
1084 Format: <int>
1085
Paul Menage3395ee02006-12-06 20:32:16 -08001086 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1087 the slab allocator. Saves per-node memory, but will
1088 impact performance on real NUMA hardware.
1089
Randy Dunlapa9913042005-10-23 12:57:11 -07001090 noalign [KNL,ARM]
1091
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 noapic [SMP,APIC] Tells the kernel to not make use of any
1093 IOAPICs that may be present in the system.
1094
1095 noasync [HW,M68K] Disables async and sync negotiation for
1096 all devices.
1097
1098 nobats [PPC] Do not use BATs for mapping kernel lowmem
1099 on "Classic" PPC cores.
1100
1101 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001102
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001103 nodelayacct [KNL] Disable per-task delay accounting
1104
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1106
1107 noexec [IA-64]
1108
Randy Dunlapa9913042005-10-23 12:57:11 -07001109 noexec [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 noexec=on: enable non-executable mappings (default)
1111 noexec=off: disable nn-executable mappings
1112
Chuck Ebbert4f886512006-03-23 02:59:34 -08001113 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1114 register save and restore. The kernel will only save
1115 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
1117 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001118
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1120 instruction doesn't work correctly and not to
1121 use it.
1122
1123 nohalt [IA-64] Tells the kernel not to use the power saving
1124 function PAL_HALT_LIGHT when idle. This increases
1125 power-consumption. On the positive side, it reduces
1126 interrupt wake-up latency, which may improve performance
1127 in certain environments such as networked servers or
1128 real-time systems.
1129
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001130 nohz= [KNL] Boottime enable/disable dynamic ticks
1131 Valid arguments: on, off
1132 Default: on
1133
Zachary Amsden8542b202006-12-07 02:14:09 +01001134 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1135
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 noirqdebug [IA-32] Disables the code which attempts to detect and
1137 disable unhandled interrupt sources.
1138
Zachary Amsden8542b202006-12-07 02:14:09 +01001139 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1140 broken timer IRQ sources.
1141
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 noisapnp [ISAPNP] Disables ISA PnP code.
1143
1144 noinitrd [RAM] Tells the kernel not to load any configured
1145 initial RAM disk.
1146
1147 nointroute [IA-64]
1148
1149 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1150
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001151 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1152
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 noltlbs [PPC] Do not use large page/tlb entries for kernel
1154 lowmem mapping on PPC40x.
1155
Horms312f1f02006-02-22 09:57:55 +09001156 nomca [IA-64] Disable machine check abort handling
1157
Hormsabe37e52006-04-01 01:36:09 +02001158 nomce [IA-32] Machine Check Exception
1159
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160 noresidual [PPC] Don't use residual data on PReP machines.
1161
Randy Dunlapa9913042005-10-23 12:57:11 -07001162 noresume [SWSUSP] Disables resume and restores original swap
1163 space.
1164
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 no-scroll [VGA] Disables scrollback.
1166 This is required for the Braillex ib80-piezo Braille
1167 reader made by F.H. Papenmeier (Germany).
1168
1169 nosbagart [IA-64]
1170
Chuck Ebbert4f886512006-03-23 02:59:34 -08001171 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1172
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1174
1175 nosync [HW,M68K] Disables sync negotiation for all devices.
1176
1177 notsc [BUGS=IA-32] Disable Time Stamp Counter
1178
1179 nousb [USB] Disable the USB subsystem
1180
1181 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001182
Dave Jonesa61c2d72006-01-07 23:18:19 +00001183 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1184
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185 opl3= [HW,OSS]
1186 Format: <io>
1187
Randy Dunlapa9913042005-10-23 12:57:11 -07001188 opl3sa2= [HW,OSS] Format:
1189 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1190
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 oprofile.timer= [HW]
1192 Use timer interrupt instead of performance counters
1193
1194 optcd= [HW,CD]
1195 Format: <io>
1196
1197 osst= [HW,SCSI] SCSI Tape Driver
1198 Format: <buffer_size>,<write_threshold>
1199 See also Documentation/scsi/st.txt.
1200
1201 panic= [KNL] Kernel behaviour on panic
1202 Format: <timeout>
1203
1204 parkbd.port= [HW] Parallel port number the keyboard adapter is
1205 connected to, default is 0.
1206 Format: <parport#>
1207 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1208 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001209 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210
Randy Dunlapa9913042005-10-23 12:57:11 -07001211 parport= [HW,PPT] Specify parallel ports. 0 disables.
1212 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1213 Use 'auto' to force the driver to use any
1214 IRQ/DMA settings detected (the default is to
1215 ignore detected IRQ/DMA settings because of
1216 possible conflicts). You can specify the base
1217 address, IRQ, and DMA settings; IRQ and DMA
1218 should be numbers, or 'auto' (for using detected
1219 settings on that particular port), or 'nofifo'
1220 (to avoid using a FIFO even if it is detected).
1221 Parallel ports are assigned in the order they
1222 are specified on the command line, starting
1223 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224
Randy Dunlapa9913042005-10-23 12:57:11 -07001225 parport_init_mode= [HW,PPT]
1226 Configure VIA parallel port to operate in
1227 a specific mode. This is necessary on Pegasos
1228 computer where firmware has no options for setting
1229 up parallel port mode and sets it to spp.
1230 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 Format: [spp|ps2|epp|ecp|ecpepp]
1232
Randy Dunlapa9913042005-10-23 12:57:11 -07001233 pas2= [HW,OSS] Format:
1234 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1235
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 pas16= [HW,SCSI]
1237 See header of drivers/scsi/pas16.c.
1238
Andrew Mortondd287792006-03-23 03:00:57 -08001239 pause_on_oops=
1240 Halt all CPUs after the first oops has been printed for
1241 the specified number of seconds. This is to be used if
1242 your oopses keep scrolling off the screen.
1243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 pcbit= [HW,ISDN]
1245
1246 pcd. [PARIDE]
1247 See header of drivers/block/paride/pcd.c.
1248 See also Documentation/paride.txt.
1249
Randy Dunlapa9913042005-10-23 12:57:11 -07001250 pci=option[,option...] [PCI] various PCI subsystem options:
1251 off [IA-32] don't probe for the PCI bus
1252 bios [IA-32] force use of PCI BIOS, don't access
1253 the hardware directly. Use this if your machine
1254 has a non-standard PCI host bridge.
1255 nobios [IA-32] disallow use of PCI BIOS, only direct
1256 hardware access methods are allowed. Use this
1257 if you experience crashes upon bootup and you
1258 suspect they are caused by the BIOS.
1259 conf1 [IA-32] Force use of PCI Configuration
1260 Mechanism 1.
1261 conf2 [IA-32] Force use of PCI Configuration
1262 Mechanism 2.
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001263 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1264 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001265 nomsi [MSI] If the PCI_MSI kernel config parameter is
1266 enabled, this kernel boot option can be used to
1267 disable the use of MSI interrupts system-wide.
Randy Dunlapa9913042005-10-23 12:57:11 -07001268 nosort [IA-32] Don't sort PCI devices according to
1269 order given by the PCI BIOS. This sorting is
1270 done to get a device order compatible with
1271 older kernels.
1272 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1273 routing table. These calls are known to be buggy
1274 on several machines and they hang the machine
1275 when used, but on other computers it's the only
1276 way to get the interrupt routing table. Try
1277 this option if the kernel is unable to allocate
1278 IRQs or discover secondary PCI buses on your
1279 motherboard.
1280 rom [IA-32] Assign address space to expansion ROMs.
1281 Use with caution as certain devices share
1282 address decoders between ROMs and other
1283 resources.
1284 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1285 assigned automatically to PCI devices. You can
1286 make the kernel exclude IRQs of your ISA cards
1287 this way.
jayalk@intworks.biz120bb422005-03-21 20:20:42 -08001288 pirqaddr=0xAAAAA [IA-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001289 of the PIRQ table (normally generated
1290 by the BIOS) if it is outside the
1291 F0000h-100000h range.
1292 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1293 useful if the kernel is unable to find your
1294 secondary buses and you want to tell it
1295 explicitly which ones they are.
1296 assign-busses [IA-32] Always assign all PCI bus
1297 numbers ourselves, overriding
1298 whatever the firmware may have done.
1299 usepirqmask [IA-32] Honor the possible IRQ mask stored
1300 in the BIOS $PIR table. This is needed on
1301 some systems with broken BIOSes, notably
1302 some HP Pavilion N5400 and Omnibook XE3
1303 notebooks. This will have no effect if ACPI
1304 IRQ routing is enabled.
1305 noacpi [IA-32] Do not use ACPI for IRQ routing
1306 or for PCI scanning.
1307 routeirq Do IRQ routing for all PCI devices.
1308 This is normally done in pci_enable_device(),
1309 so this option is a temporary workaround
1310 for broken drivers that don't call it.
1311 firmware [ARM] Do not re-enumerate the bus but instead
1312 just use the configuration from the
1313 bootloader. This is currently used on
1314 IXP2000 systems where the bus has to be
1315 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001316 noearly [X86] Don't do any early type 1 scanning.
1317 This might help on some broken boards which
1318 machine check when some devices' config space
1319 is read. But various workarounds are disabled
1320 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001321 bfsort Sort PCI devices into breadth-first order.
1322 This sorting is done to get a device
1323 order compatible with older (<= 2.4) kernels.
1324 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001325 cbiosize=nn[KMG] The fixed amount of bus space which is
1326 reserved for the CardBus bridge's IO window.
1327 The default value is 256 bytes.
1328 cbmemsize=nn[KMG] The fixed amount of bus space which is
1329 reserved for the CardBus bridge's memory
1330 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001331
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 pcmv= [HW,PCMCIA] BadgePAD 4
1333
1334 pd. [PARIDE]
1335 See Documentation/paride.txt.
1336
1337 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1338 boot time.
1339 Format: { 0 | 1 }
1340 See arch/parisc/kernel/pdc_chassis.c
1341
1342 pf. [PARIDE]
1343 See Documentation/paride.txt.
1344
1345 pg. [PARIDE]
1346 See Documentation/paride.txt.
1347
1348 pirq= [SMP,APIC] Manual mp-table setup
1349 See Documentation/i386/IO-APIC.txt.
1350
1351 plip= [PPT,NET] Parallel port network link
1352 Format: { parport<nr> | timid | 0 }
1353 See also Documentation/parport.txt.
1354
1355 pnpacpi= [ACPI]
1356 { off }
1357
1358 pnpbios= [ISAPNP]
1359 { on | off | curr | res | no-curr | no-res }
1360
1361 pnp_reserve_irq=
1362 [ISAPNP] Exclude IRQs for the autoconfiguration
1363
1364 pnp_reserve_dma=
1365 [ISAPNP] Exclude DMAs for the autoconfiguration
1366
1367 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001368 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369
1370 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001371 [ISAPNP] Exclude memory regions for the
1372 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 Ranges are in pairs (memory base and size).
1374
1375 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001376 Format: [schedule,]<number>
1377 Param: "schedule" - profile schedule points.
1378 Param: <number> - step/bucket size as a power of 2 for
1379 statistical time based profiling.
Ingo Molnarece8a682006-12-06 20:37:24 -08001380 Param: "sleep" - profile D-state sleeping (millisecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381
Randy Dunlapa9913042005-10-23 12:57:11 -07001382 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 Limit processor to maximum C-state
1384 max_cstate=9 overrides any DMI blacklist limit.
1385
Len Brown41c0d862005-12-28 12:43:51 -05001386 processor.nocst [HW,ACPI]
1387 Ignore the _CST method to determine C-states,
1388 instead using the legacy FADT method
1389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1391 before loading.
1392 See Documentation/ramdisk.txt.
1393
Randy Dunlapa9913042005-10-23 12:57:11 -07001394 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1395 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1397 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001398 psmouse.resetafter= [HW,MOUSE]
1399 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 (0 = never).
1401 psmouse.resolution=
1402 [HW,MOUSE] Set desired mouse resolution, in dpi.
1403 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001404 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 0 = disabled, 1 = enabled (default).
1406
1407 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001408 Format:
1409 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410
1411 pt. [PARIDE]
1412 See Documentation/paride.txt.
1413
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001414 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001415
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 r128= [HW,DRM]
1417
1418 raid= [HW,RAID]
1419 See Documentation/md.txt.
1420
1421 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1422 See Documentation/ramdisk.txt.
1423
Randy Dunlapa9913042005-10-23 12:57:11 -07001424 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001426
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1428 New name for the ramdisk parameter.
1429 See Documentation/ramdisk.txt.
1430
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001431 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1432 RCU callbacks to process in one batch.
1433
1434 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1435 RCU callbacks over which batch limiting is disabled.
1436
1437 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1438 RCU callbacks below which batch limiting is re-enabled.
1439
Olof Johanssonffdfc402005-09-06 15:17:19 -07001440 rdinit= [KNL]
1441 Format: <full_path>
1442 Run specified binary instead of /init from the ramdisk,
1443 used for early userspace startup. See initrd.
1444
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1446 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Michael Opdenackerf3e299f2006-10-03 23:19:24 +02001447 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
1449 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1450
Zachary Amsden461a9af2006-09-25 23:32:25 -07001451 reservetop= [IA-32]
1452 Format: nn[KMG]
1453 Reserves a hole at the top of the kernel virtual
1454 address space.
1455
Vivek Goyal7e962872006-09-27 01:50:44 -07001456 reset_devices [KNL] Force drivers to reset the underlying device
1457 during initialization.
1458
Randy Dunlapa9913042005-10-23 12:57:11 -07001459 resume= [SWSUSP]
1460 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001462 resume_offset= [SWSUSP]
1463 Specify the offset from the beginning of the partition
1464 given by "resume=" at which the swap header is located,
1465 in <PAGE_SIZE> units (needed only for swap files).
1466 See Documentation/power/swsusp-and-swap-files.txt
1467
Michael Neuling0a7b35c2007-02-10 01:44:33 -08001468 retain_initrd [RAM] Keep initrd memory after extraction
1469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 rhash_entries= [KNL,NET]
1471 Set number of hash buckets for route cache
1472
1473 riscom8= [HW,SERIAL]
1474 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1475
1476 ro [KNL] Mount root device read-only on boot
1477
1478 root= [KNL] Root filesystem
1479
1480 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1481 mount the root filesystem
1482
1483 rootflags= [KNL] Set root filesystem mount option string
1484
1485 rootfstype= [KNL] Set root filesystem type
1486
1487 rw [KNL] Mount root device read-write on boot
1488
1489 S [KNL] Run init in single mode
1490
1491 sa1100ir [NET]
1492 See drivers/net/irda/sa1100_ir.c.
1493
1494 sb= [HW,OSS]
1495 Format: <io>,<irq>,<dma>,<dma2>
1496
1497 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001498
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 sbpcd= [HW,CD] Soundblaster CD adapter
1500 Format: <io>,<type>
1501 See a comment before function sbpcd_setup() in
1502 drivers/cdrom/sbpcd.c.
1503
1504 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1505 Format: <io>[,<timeout>[,<isapnp>]]
1506
1507 scsi_debug_*= [SCSI]
1508 See drivers/scsi/scsi_debug.c.
1509
1510 scsi_default_dev_flags=
1511 [SCSI] SCSI default device flags
1512 Format: <integer>
1513
1514 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1515 Format: <vendor>:<model>:<flags>
1516 (flags are integer value)
1517
1518 scsi_logging= [SCSI]
1519
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001520 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1521 discovered. async scans them in kernel threads,
1522 allowing boot to proceed. none ignores them, expecting
1523 user space to do the scan.
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 selinux [SELINUX] Disable or enable SELinux at boot time.
1526 Format: { "0" | "1" }
1527 See security/selinux/Kconfig help text.
1528 0 -- disable.
1529 1 -- enable.
1530 Default value is set via kernel config option.
1531 If enabled at boot time, /selinux/disable can be used
1532 later to disable prior to initial policy load.
1533
James Morris4e5ab4c2006-06-09 00:33:33 -07001534 selinux_compat_net =
1535 [SELINUX] Set initial selinux_compat_net flag value.
1536 Format: { "0" | "1" }
1537 0 -- use new secmark-based packet controls
1538 1 -- use legacy packet controls
1539 Default value is 0 (preferred).
1540 Value can be changed at runtime via
1541 /selinux/compat_net.
1542
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 serialnumber [BUGS=IA-32]
1544
Randy Dunlapa9913042005-10-23 12:57:11 -07001545 sg_def_reserved_size= [SCSI]
1546
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 shapers= [NET]
1548 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001549
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 sim710= [SCSI,HW]
1551 See header of drivers/scsi/sim710.c.
1552
1553 simeth= [IA-64]
1554 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 sjcd= [HW,CD]
1557 Format: <io>,<irq>,<dma>
1558 See header of drivers/cdrom/sjcd.c.
1559
1560 slram= [HW,MTD]
1561
1562 smart2= [HW]
1563 Format: <io1>[,<io2>[,...,<io8>]]
1564
1565 snd-ad1816a= [HW,ALSA]
1566
1567 snd-ad1848= [HW,ALSA]
1568
1569 snd-ali5451= [HW,ALSA]
1570
1571 snd-als100= [HW,ALSA]
1572
1573 snd-als4000= [HW,ALSA]
1574
1575 snd-azt2320= [HW,ALSA]
1576
1577 snd-cmi8330= [HW,ALSA]
1578
1579 snd-cmipci= [HW,ALSA]
1580
1581 snd-cs4231= [HW,ALSA]
1582
1583 snd-cs4232= [HW,ALSA]
1584
1585 snd-cs4236= [HW,ALSA]
1586
1587 snd-cs4281= [HW,ALSA]
1588
1589 snd-cs46xx= [HW,ALSA]
1590
1591 snd-dt019x= [HW,ALSA]
1592
1593 snd-dummy= [HW,ALSA]
1594
1595 snd-emu10k1= [HW,ALSA]
1596
1597 snd-ens1370= [HW,ALSA]
1598
1599 snd-ens1371= [HW,ALSA]
1600
1601 snd-es968= [HW,ALSA]
1602
1603 snd-es1688= [HW,ALSA]
1604
1605 snd-es18xx= [HW,ALSA]
1606
1607 snd-es1938= [HW,ALSA]
1608
1609 snd-es1968= [HW,ALSA]
1610
1611 snd-fm801= [HW,ALSA]
1612
1613 snd-gusclassic= [HW,ALSA]
1614
1615 snd-gusextreme= [HW,ALSA]
1616
1617 snd-gusmax= [HW,ALSA]
1618
1619 snd-hdsp= [HW,ALSA]
1620
1621 snd-ice1712= [HW,ALSA]
1622
1623 snd-intel8x0= [HW,ALSA]
1624
1625 snd-interwave= [HW,ALSA]
1626
1627 snd-interwave-stb=
1628 [HW,ALSA]
1629
1630 snd-korg1212= [HW,ALSA]
1631
1632 snd-maestro3= [HW,ALSA]
1633
1634 snd-mpu401= [HW,ALSA]
1635
1636 snd-mtpav= [HW,ALSA]
1637
1638 snd-nm256= [HW,ALSA]
1639
1640 snd-opl3sa2= [HW,ALSA]
1641
1642 snd-opti92x-ad1848=
1643 [HW,ALSA]
1644
1645 snd-opti92x-cs4231=
1646 [HW,ALSA]
1647
1648 snd-opti93x= [HW,ALSA]
1649
1650 snd-pmac= [HW,ALSA]
1651
1652 snd-rme32= [HW,ALSA]
1653
1654 snd-rme96= [HW,ALSA]
1655
1656 snd-rme9652= [HW,ALSA]
1657
1658 snd-sb8= [HW,ALSA]
1659
1660 snd-sb16= [HW,ALSA]
1661
1662 snd-sbawe= [HW,ALSA]
1663
1664 snd-serial= [HW,ALSA]
1665
1666 snd-sgalaxy= [HW,ALSA]
1667
1668 snd-sonicvibes= [HW,ALSA]
1669
1670 snd-sun-amd7930=
1671 [HW,ALSA]
1672
1673 snd-sun-cs4231= [HW,ALSA]
1674
1675 snd-trident= [HW,ALSA]
1676
1677 snd-usb-audio= [HW,ALSA,USB]
1678
1679 snd-via82xx= [HW,ALSA]
1680
1681 snd-virmidi= [HW,ALSA]
1682
1683 snd-wavefront= [HW,ALSA]
1684
1685 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 sonycd535= [HW,CD]
1688 Format: <io>[,<irq>]
1689
1690 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1691 See Documentation/sonypi.txt
1692
1693 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1694 See Documentation/specialix.txt.
1695
1696 spia_io_base= [HW,MTD]
1697 spia_fio_base=
1698 spia_pedr=
1699 spia_peddr=
1700
1701 sscape= [HW,OSS]
1702 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1705 See Documentation/scsi/st.txt.
1706
1707 st0x= [HW,SCSI]
1708 See header of drivers/scsi/seagate.c.
1709
1710 sti= [PARISC,HW]
1711 Format: <num>
1712 Set the STI (builtin display/keyboard on the HP-PARISC
1713 machines) console (graphic card) which should be used
1714 as the initial boot-console.
1715 See also comment in drivers/video/console/sticore.c.
1716
1717 sti_font= [HW]
1718 See comment in drivers/video/console/sticore.c.
1719
1720 stifb= [HW]
1721 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1722
Greg Banks42a7fc42007-03-06 01:42:23 -08001723 sunrpc.pool_mode=
1724 [NFS]
1725 Control how the NFS server code allocates CPUs to
1726 service thread pools. Depending on how many NICs
1727 you have and where their interrupts are bound, this
1728 option will affect which CPUs will do NFS serving.
1729 Note: this parameter cannot be changed while the
1730 NFS server is running.
1731
1732 auto the server chooses an appropriate mode
1733 automatically using heuristics
1734 global a single global pool contains all CPUs
1735 percpu one pool for each CPU
1736 pernode one pool for each NUMA node (equivalent
1737 to global on non-NUMA machines)
1738
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 switches= [HW,M68k]
1742
1743 sym53c416= [HW,SCSI]
1744 See header of drivers/scsi/sym53c416.c.
1745
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001746 sysrq_always_enabled
1747 [KNL]
1748 Ignore sysrq setting - this boot parameter will
1749 neutralize any effect of /proc/sys/kernel/sysrq.
1750 Useful for debugging.
1751
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752 t128= [HW,SCSI]
1753 See header of drivers/scsi/t128.c.
1754
1755 tdfx= [HW,DRM]
1756
1757 thash_entries= [KNL,NET]
1758 Set number of hash buckets for TCP connection
1759
1760 time Show timing data prefixed to each printk message line
1761
john stultz734efb42006-06-26 00:25:05 -07001762 clocksource= [GENERIC_TIME] Override the default clocksource
1763 Override the default clocksource and use the clocksource
1764 with the name specified.
1765
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 tipar.timeout= [HW,PPT]
1767 Set communications timeout in tenths of a second
1768 (default 15).
1769
1770 tipar.delay= [HW,PPT]
1771 Set inter-bit delay in microseconds (default 10).
1772
1773 tmc8xx= [HW,SCSI]
1774 See header of drivers/scsi/seagate.c.
1775
1776 tmscsim= [HW,SCSI]
1777 See comment before function dc390_setup() in
1778 drivers/scsi/tmscsim.c.
1779
1780 tp720= [HW,PS2]
1781
1782 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001783 Format:
1784 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1785
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 tsdev.xres= [TS] Horizontal screen resolution.
1787 tsdev.yres= [TS] Vertical screen resolution.
1788
Randy Dunlapa9913042005-10-23 12:57:11 -07001789 turbografx.map[2|3]= [HW,JOY]
1790 TurboGraFX parallel port interface
1791 Format:
1792 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 See also Documentation/input/joystick-parport.txt
1794
1795 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1796 See header of drivers/scsi/u14-34f.c.
1797
1798 uart401= [HW,OSS]
1799 Format: <io>,<irq>
1800
1801 uart6850= [HW,OSS]
1802 Format: <io>,<irq>
1803
Alan Stern5f8364b2006-12-05 16:29:55 -05001804 uhci-hcd.ignore_oc=
1805 [USB] Ignore overcurrent events (default N).
1806 Some badly-designed motherboards generate lots of
1807 bogus events, for ports that aren't wired to
1808 anything. Set this parameter to avoid log spamming.
1809 Note that genuine overcurrent events won't be
1810 reported either.
1811
Alan Sternb5e795f2007-02-20 15:00:53 -05001812 usbcore.autosuspend=
1813 [USB] The autosuspend time delay (in seconds) used
1814 for newly-detected USB devices (default 2). This
1815 is the time required before an idle device will be
1816 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04001817 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05001818
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819 usbhid.mousepoll=
1820 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07001821
Paul Mundte523d932007-02-28 18:30:01 +09001822 vdso= [IA-32,SH]
Ingo Molnare6e54942006-06-27 02:53:50 -07001823 vdso=1: enable VDSO (default)
1824 vdso=0: disable VDSO mapping
1825
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 video= [FB] Frame buffer configuration
1827 See Documentation/fb/modedb.txt.
1828
1829 vga= [BOOT,IA-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07001830 See Documentation/i386/boot.txt and
1831 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 Use vga=ask for menu.
1833 This is actually a boot loader parameter; the value is
1834 passed to the kernel using a special protocol.
1835
Randy Dunlapa9913042005-10-23 12:57:11 -07001836 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837 size of <nn>. This can be used to increase the
1838 minimum size (128MB on x86). It can also be used to
1839 decrease the size and leave more room for directly
1840 mapped kernel RAM.
1841
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001842 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1843 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001845 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1846 Format: <command>
1847
1848 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1849 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07001850
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851 waveartist= [HW,OSS]
1852 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07001853
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 wd33c93= [HW,SCSI]
1855 See header of drivers/scsi/wd33c93.c.
1856
1857 wd7000= [HW,SCSI]
1858 See header of drivers/scsi/wd7000.c.
1859
1860 wdt= [WDT] Watchdog
1861 See Documentation/watchdog/watchdog.txt.
1862
1863 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1864 xd_geo= See header of drivers/block/xd.c.
1865
1866 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001867 Format:
1868 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869
Andi Kleena62eaf12006-02-16 23:41:58 +01001870 norandmaps Don't use address space randomization
1871 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1872
Jan Beulich6d0185e2006-12-07 02:14:13 +01001873 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1874 This is useful to get more information why
1875 you got a "dwarf2 unwinder stuck"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876
Randy Dunlapa9913042005-10-23 12:57:11 -07001877______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878
1879TODO:
1880
1881 Add documentation for ALSA options.
1882 Add more DRM drivers.