blob: 6e92ba61f7c0ea18b86557eec2bd17f2ece5d9ca [file] [log] [blame]
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.
82 SMP The kernel is an SMP kernel.
83 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070084 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 TS Appropriate touchscreen support is enabled.
86 USB USB support is enabled.
87 USBHID USB Human Interface Device support is enabled.
88 V4L Video For Linux support is enabled.
89 VGA The VGA console has been enabled.
90 VT Virtual terminal support is enabled.
91 WDT Watchdog support is enabled.
92 XT IBM PC/XT MFM hard disk support is enabled.
93 X86-64 X86-64 architecture is enabled.
94 More X86-64 boot options can be found in
95 Documentation/x86_64/boot-options.txt .
96
97In addition, the following text indicates that the option:
98
99 BUGS= Relates to possible processor bugs on the said processor.
100 KNL Is a kernel start-up parameter.
101 BOOT Is a boot loader parameter.
102
103Parameters denoted with BOOT are actually interpreted by the boot
104loader, and have no meaning to the kernel directly.
105Do not modify the syntax of boot loader parameters without extreme
106need or coordination with <Documentation/i386/boot.txt>.
107
Karsten Weiss55588702007-02-13 13:26:21 +0100108There are also arch-specific kernel-parameters not documented here.
109See for example <Documentation/x86_64/boot-options.txt>.
110
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
112a trailing = on the name of any parameter states that that parameter will
113be entered as an environment variable, whereas its absence indicates that
114it will appear as a kernel argument readable via /proc/cmdline by programs
115running once the system is up.
116
jens m. noedler9c4751f2006-09-29 02:00:27 -0700117The number of kernel parameters is not limited, but the length of the
118complete command line (parameters including spaces etc.) is limited to
119a fixed number of characters. This limit depends on the architecture
120and is between 256 and 4096 characters. It is defined in the file
121./include/asm/setup.h as COMMAND_LINE_SIZE.
122
123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 53c7xx= [HW,SCSI] Amiga SCSI controllers
125 See header of drivers/scsi/53c7xx.c.
126 See also Documentation/scsi/ncr53c7xx.txt.
127
Randy Dunlapa9913042005-10-23 12:57:11 -0700128 acpi= [HW,ACPI] Advanced Configuration and Power Interface
129 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 force -- enable ACPI if default was off
131 off -- disable ACPI if default was on
132 noirq -- do not use ACPI for IRQ routing
133 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700134 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 strictly ACPI specification compliant.
136
137 See also Documentation/pm.txt, pci=noacpi
138
139 acpi_sleep= [HW,ACPI] Sleep options
140 Format: { s3_bios, s3_mode }
141 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700142
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700144 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Randy Dunlapa9913042005-10-23 12:57:11 -0700146 acpi_irq_balance [HW,ACPI]
147 ACPI will balance active IRQs
148 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
Randy Dunlapa9913042005-10-23 12:57:11 -0700150 acpi_irq_nobalance [HW,ACPI]
151 ACPI will not move active IRQs (default)
152 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
Randy Dunlapa9913042005-10-23 12:57:11 -0700154 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
155 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 Format: <irq>,<irq>...
157
Randy Dunlapa9913042005-10-23 12:57:11 -0700158 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 Format: <irq>,<irq>...
160
Len Browna1f9e652006-01-25 23:47:36 -0500161 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
162 Format: To spoof as Windows 98: ="Microsoft Windows"
163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 acpi_osi= [HW,ACPI] empty param disables _OSI
165
166 acpi_serialize [HW,ACPI] force serialization of AML methods
167
168 acpi_skip_timer_override [HW,ACPI]
169 Recognize and ignore IRQ0/pin2 Interrupt Override.
170 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100171 acpi_use_timer_override [HW,ACPI}
172 Use timer override. For some broken Nvidia NF5 boards
173 that require a timer override, but don't have
174 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
176 acpi_dbg_layer= [HW,ACPI]
177 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700178 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 1: enable, 0: disable. It is useful for boot time
180 debugging. After system has booted up, it can be set
181 via /proc/acpi/debug_layer.
182
183 acpi_dbg_level= [HW,ACPI]
184 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700185 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 1: enable, 0: disable. It is useful for boot time
187 debugging. After system has booted up, it can be set
188 via /proc/acpi/debug_level.
189
190 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
191
Luming Yu30e332f2005-08-12 00:31:00 -0400192 acpi_generic_hotkey [HW,ACPI]
193 Allow consolidated generic hotkey driver to
Randy Dunlapa9913042005-10-23 12:57:11 -0700194 override platform specific driver.
Luming Yu30e332f2005-08-12 00:31:00 -0400195 See also Documentation/acpi-hotkey.txt.
196
john stultz5d0cf412006-06-26 00:25:12 -0700197 acpi_pm_good [IA-32,X86-64]
198 Override the pmtimer bug detection: force the kernel
199 to assume that this machine's pmtimer latches its value
200 and always returns good values.
201
Chuck Ebbert66759a02005-09-12 18:49:25 +0200202 enable_timer_pin_1 [i386,x86-64]
203 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700204 Can be useful to work around chipset bugs
205 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200206 The kernel tries to set a reasonable default.
207
208 disable_timer_pin_1 [i386,x86-64]
209 Disable PIN 1 of APIC timer
210 Can be useful to work around chipset bugs.
211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 ad1816= [HW,OSS]
213 Format: <io>,<irq>,<dma>,<dma2>
214 See also Documentation/sound/oss/AD1816.
215
216 ad1848= [HW,OSS]
217 Format: <io>,<irq>,<dma>,<dma2>,<type>
218
219 adlib= [HW,OSS]
220 Format: <io>
Randy Dunlapa9913042005-10-23 12:57:11 -0700221
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 advansys= [HW,SCSI]
223 See header of drivers/scsi/advansys.c.
224
225 advwdt= [HW,WDT] Advantech WDT
226 Format: <iostart>,<iostop>
227
228 aedsp16= [HW,OSS] Audio Excel DSP 16
229 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
230 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700231
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 aha152x= [HW,SCSI]
233 See Documentation/scsi/aha152x.txt.
234
235 aha1542= [HW,SCSI]
236 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
237
238 aic7xxx= [HW,SCSI]
239 See Documentation/scsi/aic7xxx.txt.
240
241 aic79xx= [HW,SCSI]
242 See Documentation/scsi/aic79xx.txt.
243
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 amijoy.map= [HW,JOY] Amiga joystick support
245 Map of devices attached to JOY0DAT and JOY1DAT
246 Format: <a>,<b>
247 See also Documentation/kernel/input/joystick.txt
248
249 analog.map= [HW,JOY] Analog joystick and gamepad support
250 Specifies type or capabilities of an analog joystick
251 connected to one of 16 gameports
252 Format: <type1>,<type2>,..<type16>
253
Randy Dunlapa9913042005-10-23 12:57:11 -0700254 apc= [HW,SPARC]
255 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 Format: noidle
257 Disable APC CPU standby support. SPARCstation-Fox does
258 not play well with APC CPU idle - disable it if you have
259 APC and your system crashes randomly.
260
Randy Dunlapa9913042005-10-23 12:57:11 -0700261 apic= [APIC,i386] Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 Format: { quiet (default) | verbose | debug }
263 Change the amount of debugging information output
264 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700265
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 apm= [APM] Advanced Power Management
267 See header of arch/i386/kernel/apm.c.
268
269 applicom= [HW]
270 Format: <mem>,<irq>
Randy Dunlapa9913042005-10-23 12:57:11 -0700271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
273 Format: <io>,<irq>,<nodeID>
274
275 ataflop= [HW,M68k]
276
277 atarimouse= [HW,MOUSE] Atari Mouse
278
279 atascsi= [HW,SCSI] Atari SCSI
280
281 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
282 EzKey and similar keyboards
283
284 atkbd.reset= [HW] Reset keyboard during initialization
285
Randy Dunlapa9913042005-10-23 12:57:11 -0700286 atkbd.set= [HW] Select keyboard code set
287 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288
289 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
290 keyboards
291
292 atkbd.softraw= [HW] Choose between synthetic and real raw mode
293 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700294
295 atkbd.softrepeat= [HW]
296 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297
298 autotest [IA64]
299
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 aztcd= [HW,CD] Aztech CD268 CDROM driver
301 Format: <io>,0x79 (?)
302
303 baycom_epp= [HW,AX25]
304 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
307 Format: <io>,<mode>
308 See header of drivers/net/hamradio/baycom_par.c.
309
Randy Dunlapa9913042005-10-23 12:57:11 -0700310 baycom_ser_fdx= [HW,AX25]
311 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 Format: <io>,<irq>,<mode>[,<baud>]
313 See header of drivers/net/hamradio/baycom_ser_fdx.c.
314
Randy Dunlapa9913042005-10-23 12:57:11 -0700315 baycom_ser_hdx= [HW,AX25]
316 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 Format: <io>,<irq>,<mode>
318 See header of drivers/net/hamradio/baycom_ser_hdx.c.
319
320 blkmtd_device= [HW,MTD]
321 blkmtd_erasesz=
322 blkmtd_ro=
323 blkmtd_bs=
324 blkmtd_count=
325
326 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700327 bttv.radio= Most important insmod options are available as
328 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
330 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
331
332 BusLogic= [HW,SCSI]
333 See drivers/scsi/BusLogic.c, comment before function
334 BusLogic_ParseDriverOptions().
335
336 c101= [NET] Moxa C101 synchronous serial card
337
338 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
339 Sometimes CPU hardware bugs make them report the cache
340 size incorrectly. The kernel will attempt work arounds
341 to fix known problems, but for some CPUs it is not
342 possible to determine what the correct size should be.
343 This option provides an override for these situations.
344
345 cdu31a= [HW,CD]
346 Format: <io>,<irq>[,PAS]
347 See header of drivers/cdrom/cdu31a.c.
348
349 chandev= [HW,NET] Generic channel device initialisation
350
351 checkreqprot [SELINUX] Set initial checkreqprot flag value.
352 Format: { "0" | "1" }
353 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700354 0 -- check protection applied by kernel (includes
355 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 1 -- check protection requested by application.
357 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700358 Value can be changed at runtime via
359 /selinux/checkreqprot.
360
john stultz734efb42006-06-26 00:25:05 -0700361 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
362 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200363 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700364 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200365 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 Format: { pit | tsc | cyclone | pmtmr }
367
Chuck Ebbert86c41832007-02-13 13:26:25 +0100368 code_bytes [IA32] How many bytes of object code to print in an
369 oops report.
370 Range: 0 - 8192
371 Default: 64
372
Andi Kleenf9262c12006-03-08 17:57:25 -0800373 disable_8254_timer
374 enable_8254_timer
375 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
376 over the 8254 in addition to over the IO-APIC. The
377 kernel tries to set a sensible default.
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 hpet= [IA-32,HPET] option to disable HPET and use PIT.
380 Format: disable
381
382 cm206= [HW,CD]
383 Format: { auto | [<io>,][<irq>] }
384
385 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700386 Format:
387 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
390 Format: <io>[,<irq>]
391
Randy Dunlapa9913042005-10-23 12:57:11 -0700392 com90xx= [HW,NET]
393 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 Format: <io>[,<irq>[,<memstart>]]
395
396 condev= [HW,S390] console device
397 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 console= [KNL] Output console device and options.
400
401 tty<n> Use the virtual console device <n>.
402
403 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800404 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800406 the form "bbbbpnf", where "bbbb" is the baud rate,
407 "p" is parity ("n", "o", or "e"), "n" is number of
408 bits, and "f" is flow control ("r" for RTS or
409 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800411 See Documentation/serial-console.txt for more
412 information. See
413 Documentation/networking/netconsole.txt for an
414 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415
416 uart,io,<addr>[,options]
417 uart,mmio,<addr>[,options]
418 Start an early, polled-mode console on the 8250/16550
419 UART at the specified I/O port or MMIO address,
420 switching to the matching ttyS device later. The
421 options are the same as for ttyS, above.
422
423 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700424 Format:
425 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426
427 cpia_pp= [HW,PPT]
428 Format: { parport<nr> | auto | none }
429
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700430 crashkernel=nn[KMG]@ss[KMG]
431 [KNL] Reserve a chunk of physical memory to
432 hold a kernel to switch to with kexec on panic.
433
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 cs4232= [HW,OSS]
435 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
436
437 cs89x0_dma= [HW,NET]
438 Format: <dma>
439
440 cs89x0_media= [HW,NET]
441 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700442
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
Randy Dunlapa9913042005-10-23 12:57:11 -0700444
445 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 See header of drivers/s390/block/dasd_devmap.c.
447
448 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
449 (one device per port)
450 Format: <port#>,<type>
451 See also Documentation/input/joystick-parport.txt
452
453 debug [KNL] Enable kernel debugging (events log level).
454
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700455 debug_locks_verbose=
456 [KNL] verbose self-tests
457 Format=<0|1>
458 Print debugging info while doing the locking API
459 self-tests.
460 We default to 0 (no extra messages), setting it to
461 1 will print _a lot_ more information - normally
462 only useful to kernel developers.
463
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 decnet= [HW,NET]
465 Format: <area>[,<node>]
466 See also Documentation/networking/decnet.txt.
467
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 dhash_entries= [KNL]
469 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700470
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 digi= [HW,SERIAL]
472 IO parameters + enable/disable command.
473
474 digiepca= [HW,SERIAL]
475 See drivers/char/README.epca and
476 Documentation/digiepca.txt.
477
478 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
479 support available.
480 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
481
482 dmasound= [HW,OSS] Sound subsystem buffers
483
484 dscc4.setup= [NET]
485
486 dtc3181e= [HW,SCSI]
487
Randy Dunlapa9913042005-10-23 12:57:11 -0700488 earlyprintk= [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 earlyprintk=vga
490 earlyprintk=serial[,ttySn[,baudrate]]
491
Randy Dunlapa9913042005-10-23 12:57:11 -0700492 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 takes over.
494
495 Only vga or serial at a time, not both.
496
497 Currently only ttyS0 and ttyS1 are supported.
498
499 Interaction with the standard serial driver is not
500 very good.
501
502 The VGA output is eventually overwritten by the real
503 console.
504
505 eata= [HW,SCSI]
506
Len Brown53f11d42005-12-05 16:46:36 -0500507 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
508 Format: <int>
509 0: polling mode
510 non-0: interrupt mode (default)
511
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 eda= [HW,PS2]
513
514 edb= [HW,PS2]
515
516 edd= [EDD]
517 Format: {"of[f]" | "sk[ipmbr]"}
518 See comment in arch/i386/boot/edd.S
519
Randy Dunlapa9913042005-10-23 12:57:11 -0700520 eicon= [HW,ISDN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 Format: <id>,<membase>,<irq>
522
523 eisa_irq_edge= [PARISC,HW]
524 See header of drivers/parisc/eisa.c.
525
526 elanfreq= [IA-32]
527 See comment before function elanfreq_setup() in
528 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
529
530 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800531 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700532 See Documentation/block/as-iosched.txt and
533 Documentation/block/deadline-iosched.txt for details.
534
Vivek Goyalaac04b32006-01-09 20:51:47 -0800535 elfcorehdr= [IA-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700536 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800537 image elf header. Generally kexec loader will
538 pass this option to capture kernel.
539 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
541 enforcing [SELINUX] Set initial enforcing status.
542 Format: {"0" | "1"}
543 See security/selinux/Kconfig help text.
544 0 -- permissive (log only, no denials).
545 1 -- enforcing (deny and log).
546 Default value is 0.
547 Value can be changed at runtime via /selinux/enforce.
548
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 es1371= [HW,OSS]
550 Format: <spdif>,[<nomix>,[<amplifier>]]
551 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700552
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 ether= [HW,NET] Ethernet cards parameters
554 This option is obsoleted by the "netdev=" option, which
555 has equivalent usage. See its documentation for details.
556
557 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
558 Format: <io>[,<irq>]
559
Akinobu Mitade1ba092006-12-08 02:39:42 -0800560 failslab=
561 fail_page_alloc=
562 fail_make_request=[KNL]
563 General fault injection mechanism.
564 Format: <interval>,<probability>,<space>,<times>
565 See also /Documentation/fault-injection/.
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 fd_mcs= [HW,SCSI]
568 See header of drivers/scsi/fd_mcs.c.
569
570 fdomain= [HW,SCSI]
571 See header of drivers/scsi/fdomain.c.
572
573 floppy= [HW]
574 See Documentation/floppy.txt.
575
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 gamecon.map[2|3]=
577 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
578 support via parallel port (up to 5 devices per port)
579 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
580 See also Documentation/input/joystick-parport.txt
581
582 gamma= [HW,DRM]
583
584 gdth= [HW,SCSI]
585 See header of drivers/scsi/gdth.c.
586
587 gpt [EFI] Forces disk with valid GPT signature but
588 invalid Protective MBR to be treated as GPT.
589
590 gscd= [HW,CD]
591 Format: <io>
592
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 gvp11= [HW,SCSI]
594
595 hashdist= [KNL,NUMA] Large hashes allocated during boot
596 are distributed across NUMA nodes. Defaults on
597 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700598 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599
600 hcl= [IA-64] SGI's Hardware Graph compatibility layer
601
602 hd= [EIDE] (E)IDE hard drive subsystem geometry
603 Format: <cyl>,<head>,<sect>
604
605 hd?= [HW] (E)IDE subsystem
606 hd?lun= See Documentation/ide.txt.
607
608 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
609 size of <nn>. This works even on boxes that have no
610 highmem otherwise. This also works to reduce highmem
611 size on bigger boxes.
612
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800613 highres= [KNL] Enable/disable high resolution timer mode.
614 Valid parameters: "on", "off"
615 Default: "on"
616
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 hisax= [HW,ISDN]
618 See Documentation/isdn/README.HiSax.
619
620 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200623 i8042.dumbkbd [HW] Pretend that controller can only read data from
624 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 (Don't attempt to blink the leds)
626 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500627 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 i8042.nomux [HW] Don't check presence of an active multiplexing
629 controller
630 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
631 controllers
632 i8042.panicblink=
633 [HW] Frequency with which keyboard LEDs should blink
634 when kernel panics (default is 0.5 sec)
635 i8042.reset [HW] Reset the controller during init and cleanup
636 i8042.unlock [HW] Unlock (ignore) the keylock
637
638 i810= [HW,DRM]
639
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700640 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
641 indicates that the driver is running on unsupported
642 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
644 does not match list of supported models.
645 i8k.power_status
646 [HW] Report power status in /proc/i8k
647 (disabled by default)
648 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
649 capability is set.
650
651 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
652 See Documentation/mca.txt.
653
654 icn= [HW,ISDN]
655 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
656
657 ide= [HW] (E)IDE subsystem
658 Format: ide=nodma or ide=doubler or ide=reverse
659 See Documentation/ide.txt.
660
661 ide?= [HW] (E)IDE subsystem
662 Format: ide?=noprobe or chipset specific parameters.
663 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700664
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
666 See Documentation/ide.txt.
667
668 idle= [HW]
669 Format: idle=poll or idle=halt
Randy Dunlapa9913042005-10-23 12:57:11 -0700670
Ingo Molnar792908222006-12-06 20:40:51 -0800671 ignore_loglevel [KNL]
672 Ignore loglevel setting - this will print /all/
673 kernel messages to the console. Useful for debugging.
674
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 ihash_entries= [KNL]
676 Set number of hash buckets for inode cache.
677
678 in2000= [HW,SCSI]
679 See header of drivers/scsi/in2000.c.
680
681 init= [KNL]
682 Format: <full_path>
683 Run specified binary instead of /sbin/init as init
684 process.
685
686 initcall_debug [KNL] Trace initcalls as they are executed. Useful
687 for working out where the kernel is dying during
688 startup.
689
690 initrd= [BOOT] Specify the location of the initial ramdisk
691
692 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
693 Format: <irq>
694
Jesse Barnes2bd0fa32005-12-13 03:05:03 -0500695 combined_mode= [HW] control which driver uses IDE ports in combined
696 mode: legacy IDE driver, libata, or both
697 (in the libata case, libata.atapi_enabled=1 may be
698 useful as well). Note that using the ide or libata
699 options may affect your device naming (e.g. by
700 changing hdc to sdb).
701 Format: combined (default), ide, or libata
702
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 inttest= [IA64]
704
705 io7= [HW] IO7 for Marvel based alpha systems
706 See comment before marvel_specify_io7 in
707 arch/alpha/kernel/core_marvel.c.
708
709 ip= [IP_PNP]
710 See Documentation/nfsroot.txt.
711
712 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
713 See comment before ip2_setup() in drivers/char/ip2.c.
714
715 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
716 See header of drivers/scsi/ips.c.
717
Simon Horman72c4a132006-09-13 19:57:18 -0700718 ports= [IP_VS_FTP] IPVS ftp helper module
719 Default is 21.
720 Up to 8 (IP_VS_APP_MAX_PORTS) ports
721 may be specified.
722 Format: <port>,<port>....
723
Alan Cox200803d2005-06-28 20:45:18 -0700724 irqfixup [HW]
725 When an interrupt is not handled search all handlers
726 for it. Intended to get systems with badly broken
727 firmware running.
728
729 irqpoll [HW]
730 When an interrupt is not handled search all handlers
731 for it. Also check all handlers each timer
732 interrupt. Intended to get systems with badly broken
733 firmware running.
734
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700736 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737
738 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800739 Format:
740 <cpu number>,...,<cpu number>
741 or
742 <cpu number>-<cpu number> (must be a positive range in ascending order)
743 or a mixture
744 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 This option can be used to specify one or more CPUs
746 to isolate from the general SMP balancing and scheduling
747 algorithms. The only way to move a process onto or off
748 an "isolated" CPU is via the CPU affinity syscalls.
749 <cpu number> begins at 0 and the maximum value is
750 "number of CPUs in system - 1".
751
752 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700753 alternative -- manually setting the CPU mask of all
754 tasks in the system -- can cause problems and
755 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756
757 isp16= [HW,CD]
758 Format: <io>,<irq>,<dma>,<setup>
759
Randy Dunlapa9913042005-10-23 12:57:11 -0700760 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761
762 js= [HW,JOY] Analog joystick
763 See Documentation/input/joystick.txt.
764
765 keepinitrd [HW,ARM]
766
Randy Dunlapa9913042005-10-23 12:57:11 -0700767 kstack=N [IA-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 in oops dumps.
769
770 l2cr= [PPC]
771
Randy Dunlapa9913042005-10-23 12:57:11 -0700772 lapic [IA-32,APIC] Enable the local APIC even if BIOS
773 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
775 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
776 Format: addr:<io>,irq:<irq>
777
Randy Dunlapa9913042005-10-23 12:57:11 -0700778 llsc*= [IA64] See function print_params() in
779 arch/ia64/sn/kernel/llsc4.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780
781 load_ramdisk= [RAM] List of ramdisks to load from floppy
782 See Documentation/ramdisk.txt.
783
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800784 lockd.nlm_grace_period=P [NFS] Assign grace period.
785 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800787 lockd.nlm_tcpport=N [NFS] Assign TCP port.
788 Format: <integer>
789
790 lockd.nlm_timeout=T [NFS] Assign timeout value.
791 Format: <integer>
792
793 lockd.nlm_udpport=M [NFS] Assign UDP port.
794 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795
796 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
797 Format: <irq>
798
799 loglevel= All Kernel Messages with a loglevel smaller than the
800 console loglevel will be printed to the console. It can
801 also be changed with klogd or other programs. The
802 loglevels are defined as follows:
803
804 0 (KERN_EMERG) system is unusable
805 1 (KERN_ALERT) action must be taken immediately
806 2 (KERN_CRIT) critical conditions
807 3 (KERN_ERR) error conditions
808 4 (KERN_WARNING) warning conditions
809 5 (KERN_NOTICE) normal but significant condition
810 6 (KERN_INFO) informational
811 7 (KERN_DEBUG) debug-level messages
812
813 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700814 Format: { n | nk | nM }
815 n must be a power of two. The default size
816 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817
818 lp=0 [LP] Specify parallel ports to use, e.g,
819 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
820 lp=reset first parallel port). 'lp=0' disables the
821 lp=auto printer driver. 'lp=reset' (which can be
822 specified in addition to the ports) causes
823 attached printers to be reset. Using
824 lp=port1,port2,... specifies the parallel ports
825 to associate lp devices with, starting with
826 lp0. A port specification may be 'none' to skip
827 that lp device, or a parport name such as
828 'parport0'. Specifying 'lp=auto' instead of a
829 port specification list means that device IDs
830 from each port should be examined, to see if
831 an IEEE 1284-compliant printer is attached; if
832 so, the driver will manage that printer.
833 See also header of drivers/char/lp.c.
834
835 lpj=n [KNL]
836 Sets loops_per_jiffy to given constant, thus avoiding
837 time-consuming boot-time autodetection (up to 250 ms per
838 CPU). 0 enables autodetection (default). To determine
839 the correct value for your kernel, boot with normal
840 autodetection and see what value is printed. Note that
841 on SMP systems the preset will be applied to all CPUs,
842 which is likely to cause problems if your CPUs need
843 significantly divergent settings. An incorrect value
844 will cause delays in the kernel to be wrong, leading to
845 unpredictable I/O errors and other breakage. Although
846 unlikely, in the extreme case this might damage your
847 hardware.
848
849 ltpc= [NET]
850 Format: <io>,<irq>,<dma>
851
Randy Dunlapa9913042005-10-23 12:57:11 -0700852 mac5380= [HW,SCSI] Format:
853 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854
Randy Dunlapa9913042005-10-23 12:57:11 -0700855 mac53c9x= [HW,SCSI] Format:
856 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
Randy Dunlapa9913042005-10-23 12:57:11 -0700858 machvec= [IA64] Force the use of a particular machine-vector
859 (machvec) in a generic kernel.
860 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861
Randy Dunlapa9913042005-10-23 12:57:11 -0700862 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 be mounted
864 Format: <1-256>
865
866 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Randy Dunlap78f92a82007-02-17 19:58:30 +0100867 should make use of.
868 Using "nosmp" or "maxcpus=0" will disable SMP
869 entirely (the MPS table probe still happens, though).
870 A command-line option of "maxcpus=<NUM>", where <NUM>
871 is an integer greater than 0, limits the maximum number
872 of CPUs activated in SMP mode to <NUM>.
873 Using "maxcpus=1" on an SMP kernel is the trivial
874 case of an SMP kernel with only one CPU.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875
Bob Picco2b2c3752005-06-29 18:00:00 -0700876 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
877 equal to this physical address is ignored.
878
Randy Dunlapa9913042005-10-23 12:57:11 -0700879 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 Should be between 1 and 2^32-1.
881
882 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -0700883 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 Should be between 1 and 16384.
885
886 mca-pentium [BUGS=IA-32]
887
888 mcatest= [IA-64]
889
890 mcd= [HW,CD]
891 Format: <port>,<irq>,<mitsumi_bug_93_wait>
892
893 mcdx= [HW,CD]
894
895 mce [IA-32] Machine Check Exception
896
897 md= [HW] RAID subsystems devices and level
898 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700899
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 mdacon= [MDA]
901 Format: <first>,<last>
902 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -0700903
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
905 Amount of memory to be used when the kernel is not able
906 to see the whole system memory or for test.
907 [IA-32] Use together with memmap= to avoid physical
908 address space collisions. Without memmap= PCI devices
909 could be placed at addresses belonging to unused RAM.
910
911 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
912 memory.
913
akpm@osdl.org69cda7b2006-01-09 20:51:46 -0800914 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 E820 memory map, as specified by the user.
916 Such memmap=exactmap lines can be constructed based on
917 BIOS output or other requirements. See the memmap=nn@ss
918 option description.
919
920 memmap=nn[KMG]@ss[KMG]
921 [KNL] Force usage of a specific region of memory
922 Region of memory to be used, from ss to ss+nn.
923
924 memmap=nn[KMG]#ss[KMG]
925 [KNL,ACPI] Mark specific memory as ACPI data.
926 Region of memory to be used, from ss to ss+nn.
927
928 memmap=nn[KMG]$ss[KMG]
929 [KNL,ACPI] Mark specific memory as reserved.
930 Region of memory to be used, from ss to ss+nn.
931
932 meye.*= [HW] Set MotionEye Camera parameters
933 See Documentation/video4linux/meye.txt.
934
935 mga= [HW,DRM]
936
akpm@osdl.org198e2f12006-01-12 01:05:30 -0800937 migration_cost=
938 [KNL,SMP] debug: override scheduler migration costs
939 Format: <level-1-usecs>,<level-2-usecs>,...
940 This debugging option can be used to override the
941 default scheduler migration cost matrix. The numbers
942 are indexed by 'CPU domain distance'.
943 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
944 box will set up an intra-core migration cost of
945 1 msec, an inter-core migration cost of 2 msecs,
946 and an inter-node migration cost of 3 msecs.
947
948 WARNING: using the wrong values here can break
949 scheduler performance, so it's only for scheduler
950 development purposes, not production environments.
951
952 migration_debug=
953 [KNL,SMP] migration cost auto-detect verbosity
954 Format=<0|1|2>
955 If a system's migration matrix reported at bootup
956 seems erroneous then this option can be used to
957 increase verbosity of the detection process.
958 We default to 0 (no extra messages), 1 will print
959 some more information, and 2 will be really
960 verbose (probably only useful if you also have a
961 serial console attached to the system).
962
963 migration_factor=
964 [KNL,SMP] multiply/divide migration costs by a factor
965 Format=<percent>
966 This debug option can be used to proportionally
967 increase or decrease the auto-detected migration
968 costs for all entries of the migration matrix.
969 E.g. migration_factor=150 will increase migration
970 costs by 50%. (and thus the scheduler will be less
971 eager migrating cache-hot tasks)
972 migration_factor=80 will decrease migration costs
973 by 20%. (thus the scheduler will be more eager to
974 migrate tasks)
975
976 WARNING: using the wrong values here can break
977 scheduler performance, so it's only for scheduler
978 development purposes, not production environments.
979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 mousedev.tap_time=
981 [MOUSE] Maximum time between finger touching and
982 leaving touchpad surface for touch to be considered
983 a tap and be reported as a left button click (for
984 touchpads working in absolute mode only).
985 Format: <msecs>
986 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
987 reporting absolute coordinates, such as tablets
988 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
989 reporting absolute coordinates, such as tablets
990
991 mpu401= [HW,OSS]
992 Format: <io>,<irq>
993
994 MTD_Partition= [MTD]
995 Format: <name>,<region-number>,<size>,<offset>
996
Randy Dunlapa9913042005-10-23 12:57:11 -0700997 MTD_Region= [MTD] Format:
998 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999
1000 mtdparts= [MTD]
1001 See drivers/mtd/cmdline.c.
1002
1003 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001004 [HW] Make the MicroTouch USB driver use raw coordinates
1005 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
1007 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1008
1009 NCR_D700= [HW,SCSI]
1010 See header of drivers/scsi/NCR_D700.c.
1011
1012 ncr5380= [HW,SCSI]
1013
1014 ncr53c400= [HW,SCSI]
1015
1016 ncr53c400a= [HW,SCSI]
1017
1018 ncr53c406a= [HW,SCSI]
1019
1020 ncr53c8xx= [HW,SCSI]
1021
1022 netdev= [NET] Network devices parameters
1023 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1024 Note that mem_start is often overloaded to mean
1025 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001026 This usage is only documented in each driver source
1027 file if at all.
1028
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 nfsaddrs= [NFS]
1030 See Documentation/nfsroot.txt.
1031
1032 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1033 See Documentation/nfsroot.txt.
1034
Trond Myklebusta72b4422006-01-03 09:55:41 +01001035 nfs.callback_tcpport=
1036 [NFS] set the TCP port on which the NFSv4 callback
1037 channel should listen.
1038
Trond Myklebust58df0952006-01-03 09:55:57 +01001039 nfs.idmap_cache_timeout=
1040 [NFS] set the maximum lifetime for idmapper cache
1041 entries.
1042
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1044
1045 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1046 emulation library even if a 387 maths coprocessor
1047 is present.
1048
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -07001049 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1050 when set.
1051 Format: <int>
1052
Paul Menage3395ee02006-12-06 20:32:16 -08001053 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1054 the slab allocator. Saves per-node memory, but will
1055 impact performance on real NUMA hardware.
1056
Randy Dunlapa9913042005-10-23 12:57:11 -07001057 noalign [KNL,ARM]
1058
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 noapic [SMP,APIC] Tells the kernel to not make use of any
1060 IOAPICs that may be present in the system.
1061
1062 noasync [HW,M68K] Disables async and sync negotiation for
1063 all devices.
1064
1065 nobats [PPC] Do not use BATs for mapping kernel lowmem
1066 on "Classic" PPC cores.
1067
1068 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001069
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001070 nodelayacct [KNL] Disable per-task delay accounting
1071
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1073
1074 noexec [IA-64]
1075
Randy Dunlapa9913042005-10-23 12:57:11 -07001076 noexec [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 noexec=on: enable non-executable mappings (default)
1078 noexec=off: disable nn-executable mappings
1079
Chuck Ebbert4f886512006-03-23 02:59:34 -08001080 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1081 register save and restore. The kernel will only save
1082 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
1084 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001085
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1087 instruction doesn't work correctly and not to
1088 use it.
1089
1090 nohalt [IA-64] Tells the kernel not to use the power saving
1091 function PAL_HALT_LIGHT when idle. This increases
1092 power-consumption. On the positive side, it reduces
1093 interrupt wake-up latency, which may improve performance
1094 in certain environments such as networked servers or
1095 real-time systems.
1096
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001097 nohz= [KNL] Boottime enable/disable dynamic ticks
1098 Valid arguments: on, off
1099 Default: on
1100
Zachary Amsden8542b202006-12-07 02:14:09 +01001101 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1102
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 noirqdebug [IA-32] Disables the code which attempts to detect and
1104 disable unhandled interrupt sources.
1105
Zachary Amsden8542b202006-12-07 02:14:09 +01001106 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1107 broken timer IRQ sources.
1108
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 noisapnp [ISAPNP] Disables ISA PnP code.
1110
1111 noinitrd [RAM] Tells the kernel not to load any configured
1112 initial RAM disk.
1113
1114 nointroute [IA-64]
1115
1116 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1117
1118 noltlbs [PPC] Do not use large page/tlb entries for kernel
1119 lowmem mapping on PPC40x.
1120
Horms312f1f02006-02-22 09:57:55 +09001121 nomca [IA-64] Disable machine check abort handling
1122
Hormsabe37e52006-04-01 01:36:09 +02001123 nomce [IA-32] Machine Check Exception
1124
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 noresidual [PPC] Don't use residual data on PReP machines.
1126
Randy Dunlapa9913042005-10-23 12:57:11 -07001127 noresume [SWSUSP] Disables resume and restores original swap
1128 space.
1129
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 no-scroll [VGA] Disables scrollback.
1131 This is required for the Braillex ib80-piezo Braille
1132 reader made by F.H. Papenmeier (Germany).
1133
1134 nosbagart [IA-64]
1135
Chuck Ebbert4f886512006-03-23 02:59:34 -08001136 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1137
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1139
1140 nosync [HW,M68K] Disables sync negotiation for all devices.
1141
1142 notsc [BUGS=IA-32] Disable Time Stamp Counter
1143
1144 nousb [USB] Disable the USB subsystem
1145
1146 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001147
Dave Jonesa61c2d72006-01-07 23:18:19 +00001148 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1149
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150 opl3= [HW,OSS]
1151 Format: <io>
1152
Randy Dunlapa9913042005-10-23 12:57:11 -07001153 opl3sa2= [HW,OSS] Format:
1154 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1155
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 oprofile.timer= [HW]
1157 Use timer interrupt instead of performance counters
1158
1159 optcd= [HW,CD]
1160 Format: <io>
1161
1162 osst= [HW,SCSI] SCSI Tape Driver
1163 Format: <buffer_size>,<write_threshold>
1164 See also Documentation/scsi/st.txt.
1165
1166 panic= [KNL] Kernel behaviour on panic
1167 Format: <timeout>
1168
1169 parkbd.port= [HW] Parallel port number the keyboard adapter is
1170 connected to, default is 0.
1171 Format: <parport#>
1172 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1173 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001174 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
Randy Dunlapa9913042005-10-23 12:57:11 -07001176 parport= [HW,PPT] Specify parallel ports. 0 disables.
1177 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1178 Use 'auto' to force the driver to use any
1179 IRQ/DMA settings detected (the default is to
1180 ignore detected IRQ/DMA settings because of
1181 possible conflicts). You can specify the base
1182 address, IRQ, and DMA settings; IRQ and DMA
1183 should be numbers, or 'auto' (for using detected
1184 settings on that particular port), or 'nofifo'
1185 (to avoid using a FIFO even if it is detected).
1186 Parallel ports are assigned in the order they
1187 are specified on the command line, starting
1188 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
Randy Dunlapa9913042005-10-23 12:57:11 -07001190 parport_init_mode= [HW,PPT]
1191 Configure VIA parallel port to operate in
1192 a specific mode. This is necessary on Pegasos
1193 computer where firmware has no options for setting
1194 up parallel port mode and sets it to spp.
1195 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 Format: [spp|ps2|epp|ecp|ecpepp]
1197
Randy Dunlapa9913042005-10-23 12:57:11 -07001198 pas2= [HW,OSS] Format:
1199 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1200
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 pas16= [HW,SCSI]
1202 See header of drivers/scsi/pas16.c.
1203
Andrew Mortondd287792006-03-23 03:00:57 -08001204 pause_on_oops=
1205 Halt all CPUs after the first oops has been printed for
1206 the specified number of seconds. This is to be used if
1207 your oopses keep scrolling off the screen.
1208
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 pcbit= [HW,ISDN]
1210
1211 pcd. [PARIDE]
1212 See header of drivers/block/paride/pcd.c.
1213 See also Documentation/paride.txt.
1214
Randy Dunlapa9913042005-10-23 12:57:11 -07001215 pci=option[,option...] [PCI] various PCI subsystem options:
1216 off [IA-32] don't probe for the PCI bus
1217 bios [IA-32] force use of PCI BIOS, don't access
1218 the hardware directly. Use this if your machine
1219 has a non-standard PCI host bridge.
1220 nobios [IA-32] disallow use of PCI BIOS, only direct
1221 hardware access methods are allowed. Use this
1222 if you experience crashes upon bootup and you
1223 suspect they are caused by the BIOS.
1224 conf1 [IA-32] Force use of PCI Configuration
1225 Mechanism 1.
1226 conf2 [IA-32] Force use of PCI Configuration
1227 Mechanism 2.
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001228 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1229 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001230 nomsi [MSI] If the PCI_MSI kernel config parameter is
1231 enabled, this kernel boot option can be used to
1232 disable the use of MSI interrupts system-wide.
Randy Dunlapa9913042005-10-23 12:57:11 -07001233 nosort [IA-32] Don't sort PCI devices according to
1234 order given by the PCI BIOS. This sorting is
1235 done to get a device order compatible with
1236 older kernels.
1237 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1238 routing table. These calls are known to be buggy
1239 on several machines and they hang the machine
1240 when used, but on other computers it's the only
1241 way to get the interrupt routing table. Try
1242 this option if the kernel is unable to allocate
1243 IRQs or discover secondary PCI buses on your
1244 motherboard.
1245 rom [IA-32] Assign address space to expansion ROMs.
1246 Use with caution as certain devices share
1247 address decoders between ROMs and other
1248 resources.
1249 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1250 assigned automatically to PCI devices. You can
1251 make the kernel exclude IRQs of your ISA cards
1252 this way.
jayalk@intworks.biz120bb422005-03-21 20:20:42 -08001253 pirqaddr=0xAAAAA [IA-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001254 of the PIRQ table (normally generated
1255 by the BIOS) if it is outside the
1256 F0000h-100000h range.
1257 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1258 useful if the kernel is unable to find your
1259 secondary buses and you want to tell it
1260 explicitly which ones they are.
1261 assign-busses [IA-32] Always assign all PCI bus
1262 numbers ourselves, overriding
1263 whatever the firmware may have done.
1264 usepirqmask [IA-32] Honor the possible IRQ mask stored
1265 in the BIOS $PIR table. This is needed on
1266 some systems with broken BIOSes, notably
1267 some HP Pavilion N5400 and Omnibook XE3
1268 notebooks. This will have no effect if ACPI
1269 IRQ routing is enabled.
1270 noacpi [IA-32] Do not use ACPI for IRQ routing
1271 or for PCI scanning.
1272 routeirq Do IRQ routing for all PCI devices.
1273 This is normally done in pci_enable_device(),
1274 so this option is a temporary workaround
1275 for broken drivers that don't call it.
1276 firmware [ARM] Do not re-enumerate the bus but instead
1277 just use the configuration from the
1278 bootloader. This is currently used on
1279 IXP2000 systems where the bus has to be
1280 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001281 noearly [X86] Don't do any early type 1 scanning.
1282 This might help on some broken boards which
1283 machine check when some devices' config space
1284 is read. But various workarounds are disabled
1285 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001286 bfsort Sort PCI devices into breadth-first order.
1287 This sorting is done to get a device
1288 order compatible with older (<= 2.4) kernels.
1289 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001290 cbiosize=nn[KMG] The fixed amount of bus space which is
1291 reserved for the CardBus bridge's IO window.
1292 The default value is 256 bytes.
1293 cbmemsize=nn[KMG] The fixed amount of bus space which is
1294 reserved for the CardBus bridge's memory
1295 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001296
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 pcmv= [HW,PCMCIA] BadgePAD 4
1298
1299 pd. [PARIDE]
1300 See Documentation/paride.txt.
1301
1302 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1303 boot time.
1304 Format: { 0 | 1 }
1305 See arch/parisc/kernel/pdc_chassis.c
1306
1307 pf. [PARIDE]
1308 See Documentation/paride.txt.
1309
1310 pg. [PARIDE]
1311 See Documentation/paride.txt.
1312
1313 pirq= [SMP,APIC] Manual mp-table setup
1314 See Documentation/i386/IO-APIC.txt.
1315
1316 plip= [PPT,NET] Parallel port network link
1317 Format: { parport<nr> | timid | 0 }
1318 See also Documentation/parport.txt.
1319
1320 pnpacpi= [ACPI]
1321 { off }
1322
1323 pnpbios= [ISAPNP]
1324 { on | off | curr | res | no-curr | no-res }
1325
1326 pnp_reserve_irq=
1327 [ISAPNP] Exclude IRQs for the autoconfiguration
1328
1329 pnp_reserve_dma=
1330 [ISAPNP] Exclude DMAs for the autoconfiguration
1331
1332 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001333 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
1335 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001336 [ISAPNP] Exclude memory regions for the
1337 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 Ranges are in pairs (memory base and size).
1339
1340 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001341 Format: [schedule,]<number>
1342 Param: "schedule" - profile schedule points.
1343 Param: <number> - step/bucket size as a power of 2 for
1344 statistical time based profiling.
Ingo Molnarece8a682006-12-06 20:37:24 -08001345 Param: "sleep" - profile D-state sleeping (millisecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346
Randy Dunlapa9913042005-10-23 12:57:11 -07001347 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 Limit processor to maximum C-state
1349 max_cstate=9 overrides any DMI blacklist limit.
1350
Len Brown41c0d862005-12-28 12:43:51 -05001351 processor.nocst [HW,ACPI]
1352 Ignore the _CST method to determine C-states,
1353 instead using the legacy FADT method
1354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1356 before loading.
1357 See Documentation/ramdisk.txt.
1358
Randy Dunlapa9913042005-10-23 12:57:11 -07001359 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1360 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1362 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001363 psmouse.resetafter= [HW,MOUSE]
1364 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 (0 = never).
1366 psmouse.resolution=
1367 [HW,MOUSE] Set desired mouse resolution, in dpi.
1368 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001369 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 0 = disabled, 1 = enabled (default).
1371
1372 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001373 Format:
1374 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375
1376 pt. [PARIDE]
1377 See Documentation/paride.txt.
1378
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001379 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001380
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 r128= [HW,DRM]
1382
1383 raid= [HW,RAID]
1384 See Documentation/md.txt.
1385
1386 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1387 See Documentation/ramdisk.txt.
1388
Randy Dunlapa9913042005-10-23 12:57:11 -07001389 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001391
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1393 New name for the ramdisk parameter.
1394 See Documentation/ramdisk.txt.
1395
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001396 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1397 RCU callbacks to process in one batch.
1398
1399 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1400 RCU callbacks over which batch limiting is disabled.
1401
1402 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1403 RCU callbacks below which batch limiting is re-enabled.
1404
Olof Johanssonffdfc402005-09-06 15:17:19 -07001405 rdinit= [KNL]
1406 Format: <full_path>
1407 Run specified binary instead of /init from the ramdisk,
1408 used for early userspace startup. See initrd.
1409
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1411 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Michael Opdenackerf3e299f2006-10-03 23:19:24 +02001412 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413
1414 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1415
Zachary Amsden461a9aff2006-09-25 23:32:25 -07001416 reservetop= [IA-32]
1417 Format: nn[KMG]
1418 Reserves a hole at the top of the kernel virtual
1419 address space.
1420
Vivek Goyal7e962872006-09-27 01:50:44 -07001421 reset_devices [KNL] Force drivers to reset the underlying device
1422 during initialization.
1423
Randy Dunlapa9913042005-10-23 12:57:11 -07001424 resume= [SWSUSP]
1425 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001427 resume_offset= [SWSUSP]
1428 Specify the offset from the beginning of the partition
1429 given by "resume=" at which the swap header is located,
1430 in <PAGE_SIZE> units (needed only for swap files).
1431 See Documentation/power/swsusp-and-swap-files.txt
1432
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001433 retain_initrd [RAM] Keep initrd memory after extraction
1434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 rhash_entries= [KNL,NET]
1436 Set number of hash buckets for route cache
1437
1438 riscom8= [HW,SERIAL]
1439 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1440
1441 ro [KNL] Mount root device read-only on boot
1442
1443 root= [KNL] Root filesystem
1444
1445 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1446 mount the root filesystem
1447
1448 rootflags= [KNL] Set root filesystem mount option string
1449
1450 rootfstype= [KNL] Set root filesystem type
1451
1452 rw [KNL] Mount root device read-write on boot
1453
1454 S [KNL] Run init in single mode
1455
1456 sa1100ir [NET]
1457 See drivers/net/irda/sa1100_ir.c.
1458
1459 sb= [HW,OSS]
1460 Format: <io>,<irq>,<dma>,<dma2>
1461
1462 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001463
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 sbpcd= [HW,CD] Soundblaster CD adapter
1465 Format: <io>,<type>
1466 See a comment before function sbpcd_setup() in
1467 drivers/cdrom/sbpcd.c.
1468
1469 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1470 Format: <io>[,<timeout>[,<isapnp>]]
1471
1472 scsi_debug_*= [SCSI]
1473 See drivers/scsi/scsi_debug.c.
1474
1475 scsi_default_dev_flags=
1476 [SCSI] SCSI default device flags
1477 Format: <integer>
1478
1479 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1480 Format: <vendor>:<model>:<flags>
1481 (flags are integer value)
1482
1483 scsi_logging= [SCSI]
1484
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001485 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1486 discovered. async scans them in kernel threads,
1487 allowing boot to proceed. none ignores them, expecting
1488 user space to do the scan.
1489
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 selinux [SELINUX] Disable or enable SELinux at boot time.
1491 Format: { "0" | "1" }
1492 See security/selinux/Kconfig help text.
1493 0 -- disable.
1494 1 -- enable.
1495 Default value is set via kernel config option.
1496 If enabled at boot time, /selinux/disable can be used
1497 later to disable prior to initial policy load.
1498
James Morris4e5ab4c2006-06-09 00:33:33 -07001499 selinux_compat_net =
1500 [SELINUX] Set initial selinux_compat_net flag value.
1501 Format: { "0" | "1" }
1502 0 -- use new secmark-based packet controls
1503 1 -- use legacy packet controls
1504 Default value is 0 (preferred).
1505 Value can be changed at runtime via
1506 /selinux/compat_net.
1507
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 serialnumber [BUGS=IA-32]
1509
Randy Dunlapa9913042005-10-23 12:57:11 -07001510 sg_def_reserved_size= [SCSI]
1511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 shapers= [NET]
1513 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001514
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 sim710= [SCSI,HW]
1516 See header of drivers/scsi/sim710.c.
1517
1518 simeth= [IA-64]
1519 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001520
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521 sjcd= [HW,CD]
1522 Format: <io>,<irq>,<dma>
1523 See header of drivers/cdrom/sjcd.c.
1524
1525 slram= [HW,MTD]
1526
1527 smart2= [HW]
1528 Format: <io1>[,<io2>[,...,<io8>]]
1529
1530 snd-ad1816a= [HW,ALSA]
1531
1532 snd-ad1848= [HW,ALSA]
1533
1534 snd-ali5451= [HW,ALSA]
1535
1536 snd-als100= [HW,ALSA]
1537
1538 snd-als4000= [HW,ALSA]
1539
1540 snd-azt2320= [HW,ALSA]
1541
1542 snd-cmi8330= [HW,ALSA]
1543
1544 snd-cmipci= [HW,ALSA]
1545
1546 snd-cs4231= [HW,ALSA]
1547
1548 snd-cs4232= [HW,ALSA]
1549
1550 snd-cs4236= [HW,ALSA]
1551
1552 snd-cs4281= [HW,ALSA]
1553
1554 snd-cs46xx= [HW,ALSA]
1555
1556 snd-dt019x= [HW,ALSA]
1557
1558 snd-dummy= [HW,ALSA]
1559
1560 snd-emu10k1= [HW,ALSA]
1561
1562 snd-ens1370= [HW,ALSA]
1563
1564 snd-ens1371= [HW,ALSA]
1565
1566 snd-es968= [HW,ALSA]
1567
1568 snd-es1688= [HW,ALSA]
1569
1570 snd-es18xx= [HW,ALSA]
1571
1572 snd-es1938= [HW,ALSA]
1573
1574 snd-es1968= [HW,ALSA]
1575
1576 snd-fm801= [HW,ALSA]
1577
1578 snd-gusclassic= [HW,ALSA]
1579
1580 snd-gusextreme= [HW,ALSA]
1581
1582 snd-gusmax= [HW,ALSA]
1583
1584 snd-hdsp= [HW,ALSA]
1585
1586 snd-ice1712= [HW,ALSA]
1587
1588 snd-intel8x0= [HW,ALSA]
1589
1590 snd-interwave= [HW,ALSA]
1591
1592 snd-interwave-stb=
1593 [HW,ALSA]
1594
1595 snd-korg1212= [HW,ALSA]
1596
1597 snd-maestro3= [HW,ALSA]
1598
1599 snd-mpu401= [HW,ALSA]
1600
1601 snd-mtpav= [HW,ALSA]
1602
1603 snd-nm256= [HW,ALSA]
1604
1605 snd-opl3sa2= [HW,ALSA]
1606
1607 snd-opti92x-ad1848=
1608 [HW,ALSA]
1609
1610 snd-opti92x-cs4231=
1611 [HW,ALSA]
1612
1613 snd-opti93x= [HW,ALSA]
1614
1615 snd-pmac= [HW,ALSA]
1616
1617 snd-rme32= [HW,ALSA]
1618
1619 snd-rme96= [HW,ALSA]
1620
1621 snd-rme9652= [HW,ALSA]
1622
1623 snd-sb8= [HW,ALSA]
1624
1625 snd-sb16= [HW,ALSA]
1626
1627 snd-sbawe= [HW,ALSA]
1628
1629 snd-serial= [HW,ALSA]
1630
1631 snd-sgalaxy= [HW,ALSA]
1632
1633 snd-sonicvibes= [HW,ALSA]
1634
1635 snd-sun-amd7930=
1636 [HW,ALSA]
1637
1638 snd-sun-cs4231= [HW,ALSA]
1639
1640 snd-trident= [HW,ALSA]
1641
1642 snd-usb-audio= [HW,ALSA,USB]
1643
1644 snd-via82xx= [HW,ALSA]
1645
1646 snd-virmidi= [HW,ALSA]
1647
1648 snd-wavefront= [HW,ALSA]
1649
1650 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 sonycd535= [HW,CD]
1653 Format: <io>[,<irq>]
1654
1655 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1656 See Documentation/sonypi.txt
1657
1658 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1659 See Documentation/specialix.txt.
1660
1661 spia_io_base= [HW,MTD]
1662 spia_fio_base=
1663 spia_pedr=
1664 spia_peddr=
1665
1666 sscape= [HW,OSS]
1667 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001668
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1670 See Documentation/scsi/st.txt.
1671
1672 st0x= [HW,SCSI]
1673 See header of drivers/scsi/seagate.c.
1674
1675 sti= [PARISC,HW]
1676 Format: <num>
1677 Set the STI (builtin display/keyboard on the HP-PARISC
1678 machines) console (graphic card) which should be used
1679 as the initial boot-console.
1680 See also comment in drivers/video/console/sticore.c.
1681
1682 sti_font= [HW]
1683 See comment in drivers/video/console/sticore.c.
1684
1685 stifb= [HW]
1686 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1687
Greg Banks42a7fc42007-03-06 01:42:23 -08001688 sunrpc.pool_mode=
1689 [NFS]
1690 Control how the NFS server code allocates CPUs to
1691 service thread pools. Depending on how many NICs
1692 you have and where their interrupts are bound, this
1693 option will affect which CPUs will do NFS serving.
1694 Note: this parameter cannot be changed while the
1695 NFS server is running.
1696
1697 auto the server chooses an appropriate mode
1698 automatically using heuristics
1699 global a single global pool contains all CPUs
1700 percpu one pool for each CPU
1701 pernode one pool for each NUMA node (equivalent
1702 to global on non-NUMA machines)
1703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 switches= [HW,M68k]
1707
1708 sym53c416= [HW,SCSI]
1709 See header of drivers/scsi/sym53c416.c.
1710
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001711 sysrq_always_enabled
1712 [KNL]
1713 Ignore sysrq setting - this boot parameter will
1714 neutralize any effect of /proc/sys/kernel/sysrq.
1715 Useful for debugging.
1716
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 t128= [HW,SCSI]
1718 See header of drivers/scsi/t128.c.
1719
1720 tdfx= [HW,DRM]
1721
1722 thash_entries= [KNL,NET]
1723 Set number of hash buckets for TCP connection
1724
1725 time Show timing data prefixed to each printk message line
1726
john stultz734efb42006-06-26 00:25:05 -07001727 clocksource= [GENERIC_TIME] Override the default clocksource
1728 Override the default clocksource and use the clocksource
1729 with the name specified.
1730
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 tipar.timeout= [HW,PPT]
1732 Set communications timeout in tenths of a second
1733 (default 15).
1734
1735 tipar.delay= [HW,PPT]
1736 Set inter-bit delay in microseconds (default 10).
1737
1738 tmc8xx= [HW,SCSI]
1739 See header of drivers/scsi/seagate.c.
1740
1741 tmscsim= [HW,SCSI]
1742 See comment before function dc390_setup() in
1743 drivers/scsi/tmscsim.c.
1744
1745 tp720= [HW,PS2]
1746
1747 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001748 Format:
1749 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1750
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 tsdev.xres= [TS] Horizontal screen resolution.
1752 tsdev.yres= [TS] Vertical screen resolution.
1753
Randy Dunlapa9913042005-10-23 12:57:11 -07001754 turbografx.map[2|3]= [HW,JOY]
1755 TurboGraFX parallel port interface
1756 Format:
1757 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 See also Documentation/input/joystick-parport.txt
1759
1760 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1761 See header of drivers/scsi/u14-34f.c.
1762
1763 uart401= [HW,OSS]
1764 Format: <io>,<irq>
1765
1766 uart6850= [HW,OSS]
1767 Format: <io>,<irq>
1768
Alan Stern5f8364b2006-12-05 16:29:55 -05001769 uhci-hcd.ignore_oc=
1770 [USB] Ignore overcurrent events (default N).
1771 Some badly-designed motherboards generate lots of
1772 bogus events, for ports that aren't wired to
1773 anything. Set this parameter to avoid log spamming.
1774 Note that genuine overcurrent events won't be
1775 reported either.
1776
Alan Sternb5e795f2007-02-20 15:00:53 -05001777 usbcore.autosuspend=
1778 [USB] The autosuspend time delay (in seconds) used
1779 for newly-detected USB devices (default 2). This
1780 is the time required before an idle device will be
1781 autosuspended. Devices for which the delay is set
1782 to 0 won't be autosuspended at all.
1783
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 usbhid.mousepoll=
1785 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07001786
Ingo Molnare6e54942006-06-27 02:53:50 -07001787 vdso= [IA-32]
1788 vdso=1: enable VDSO (default)
1789 vdso=0: disable VDSO mapping
1790
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 video= [FB] Frame buffer configuration
1792 See Documentation/fb/modedb.txt.
1793
1794 vga= [BOOT,IA-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07001795 See Documentation/i386/boot.txt and
1796 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001797 Use vga=ask for menu.
1798 This is actually a boot loader parameter; the value is
1799 passed to the kernel using a special protocol.
1800
Randy Dunlapa9913042005-10-23 12:57:11 -07001801 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802 size of <nn>. This can be used to increase the
1803 minimum size (128MB on x86). It can also be used to
1804 decrease the size and leave more room for directly
1805 mapped kernel RAM.
1806
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001807 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1808 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001810 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1811 Format: <command>
1812
1813 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1814 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07001815
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 waveartist= [HW,OSS]
1817 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07001818
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819 wd33c93= [HW,SCSI]
1820 See header of drivers/scsi/wd33c93.c.
1821
1822 wd7000= [HW,SCSI]
1823 See header of drivers/scsi/wd7000.c.
1824
1825 wdt= [WDT] Watchdog
1826 See Documentation/watchdog/watchdog.txt.
1827
1828 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1829 xd_geo= See header of drivers/block/xd.c.
1830
1831 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001832 Format:
1833 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834
Andi Kleena62eaf12006-02-16 23:41:58 +01001835 norandmaps Don't use address space randomization
1836 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1837
Jan Beulich6d0185e2006-12-07 02:14:13 +01001838 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1839 This is useful to get more information why
1840 you got a "dwarf2 unwinder stuck"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841
Randy Dunlapa9913042005-10-23 12:57:11 -07001842______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843
1844TODO:
1845
1846 Add documentation for ALSA options.
1847 Add more DRM drivers.