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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.
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070059 MSI Message Signaled Interrupts (PCI).
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 MTD MTD support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070063 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PARIDE The ParIDE subsystem is enabled.
67 PARISC The PA-RISC architecture is enabled.
68 PCI PCI bus support is enabled.
69 PCMCIA The PCMCIA subsystem is enabled.
70 PNP Plug & Play support is enabled.
71 PPC PowerPC architecture is enabled.
72 PPT Parallel port support is enabled.
73 PS2 Appropriate PS/2 support is enabled.
74 RAM RAM disk support is enabled.
75 S390 S390 architecture is enabled.
76 SCSI Appropriate SCSI support is enabled.
77 A lot of drivers has their options described inside of
78 Documentation/scsi/.
79 SELINUX SELinux support is enabled.
80 SERIAL Serial support is enabled.
81 SMP The kernel is an SMP kernel.
82 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070083 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 TS Appropriate touchscreen support is enabled.
85 USB USB support is enabled.
86 USBHID USB Human Interface Device support is enabled.
87 V4L Video For Linux support is enabled.
88 VGA The VGA console has been enabled.
89 VT Virtual terminal support is enabled.
90 WDT Watchdog support is enabled.
91 XT IBM PC/XT MFM hard disk support is enabled.
92 X86-64 X86-64 architecture is enabled.
93 More X86-64 boot options can be found in
94 Documentation/x86_64/boot-options.txt .
95
96In addition, the following text indicates that the option:
97
98 BUGS= Relates to possible processor bugs on the said processor.
99 KNL Is a kernel start-up parameter.
100 BOOT Is a boot loader parameter.
101
102Parameters denoted with BOOT are actually interpreted by the boot
103loader, and have no meaning to the kernel directly.
104Do not modify the syntax of boot loader parameters without extreme
105need or coordination with <Documentation/i386/boot.txt>.
106
107Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
108a trailing = on the name of any parameter states that that parameter will
109be entered as an environment variable, whereas its absence indicates that
110it will appear as a kernel argument readable via /proc/cmdline by programs
111running once the system is up.
112
jens m. noedler9c4751f2006-09-29 02:00:27 -0700113The number of kernel parameters is not limited, but the length of the
114complete command line (parameters including spaces etc.) is limited to
115a fixed number of characters. This limit depends on the architecture
116and is between 256 and 4096 characters. It is defined in the file
117./include/asm/setup.h as COMMAND_LINE_SIZE.
118
119
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 53c7xx= [HW,SCSI] Amiga SCSI controllers
121 See header of drivers/scsi/53c7xx.c.
122 See also Documentation/scsi/ncr53c7xx.txt.
123
Randy Dunlapa9913042005-10-23 12:57:11 -0700124 acpi= [HW,ACPI] Advanced Configuration and Power Interface
125 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 force -- enable ACPI if default was off
127 off -- disable ACPI if default was on
128 noirq -- do not use ACPI for IRQ routing
129 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700130 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 strictly ACPI specification compliant.
132
133 See also Documentation/pm.txt, pci=noacpi
134
135 acpi_sleep= [HW,ACPI] Sleep options
136 Format: { s3_bios, s3_mode }
137 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700138
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700140 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
Randy Dunlapa9913042005-10-23 12:57:11 -0700142 acpi_irq_balance [HW,ACPI]
143 ACPI will balance active IRQs
144 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Randy Dunlapa9913042005-10-23 12:57:11 -0700146 acpi_irq_nobalance [HW,ACPI]
147 ACPI will not move active IRQs (default)
148 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
Randy Dunlapa9913042005-10-23 12:57:11 -0700150 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
151 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 Format: <irq>,<irq>...
153
Randy Dunlapa9913042005-10-23 12:57:11 -0700154 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 Format: <irq>,<irq>...
156
Len Browna1f9e652006-01-25 23:47:36 -0500157 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
158 Format: To spoof as Windows 98: ="Microsoft Windows"
159
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 acpi_osi= [HW,ACPI] empty param disables _OSI
161
162 acpi_serialize [HW,ACPI] force serialization of AML methods
163
164 acpi_skip_timer_override [HW,ACPI]
165 Recognize and ignore IRQ0/pin2 Interrupt Override.
166 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100167 acpi_use_timer_override [HW,ACPI}
168 Use timer override. For some broken Nvidia NF5 boards
169 that require a timer override, but don't have
170 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
172 acpi_dbg_layer= [HW,ACPI]
173 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700174 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 1: enable, 0: disable. It is useful for boot time
176 debugging. After system has booted up, it can be set
177 via /proc/acpi/debug_layer.
178
179 acpi_dbg_level= [HW,ACPI]
180 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700181 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 1: enable, 0: disable. It is useful for boot time
183 debugging. After system has booted up, it can be set
184 via /proc/acpi/debug_level.
185
186 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
187
Luming Yu30e332f2005-08-12 00:31:00 -0400188 acpi_generic_hotkey [HW,ACPI]
189 Allow consolidated generic hotkey driver to
Randy Dunlapa9913042005-10-23 12:57:11 -0700190 override platform specific driver.
Luming Yu30e332f2005-08-12 00:31:00 -0400191 See also Documentation/acpi-hotkey.txt.
192
john stultz5d0cf412006-06-26 00:25:12 -0700193 acpi_pm_good [IA-32,X86-64]
194 Override the pmtimer bug detection: force the kernel
195 to assume that this machine's pmtimer latches its value
196 and always returns good values.
197
Chuck Ebbert66759a02005-09-12 18:49:25 +0200198 enable_timer_pin_1 [i386,x86-64]
199 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700200 Can be useful to work around chipset bugs
201 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200202 The kernel tries to set a reasonable default.
203
204 disable_timer_pin_1 [i386,x86-64]
205 Disable PIN 1 of APIC timer
206 Can be useful to work around chipset bugs.
207
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 ad1816= [HW,OSS]
209 Format: <io>,<irq>,<dma>,<dma2>
210 See also Documentation/sound/oss/AD1816.
211
212 ad1848= [HW,OSS]
213 Format: <io>,<irq>,<dma>,<dma2>,<type>
214
215 adlib= [HW,OSS]
216 Format: <io>
Randy Dunlapa9913042005-10-23 12:57:11 -0700217
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 advansys= [HW,SCSI]
219 See header of drivers/scsi/advansys.c.
220
221 advwdt= [HW,WDT] Advantech WDT
222 Format: <iostart>,<iostop>
223
224 aedsp16= [HW,OSS] Audio Excel DSP 16
225 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
226 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700227
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 aha152x= [HW,SCSI]
229 See Documentation/scsi/aha152x.txt.
230
231 aha1542= [HW,SCSI]
232 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
233
234 aic7xxx= [HW,SCSI]
235 See Documentation/scsi/aic7xxx.txt.
236
237 aic79xx= [HW,SCSI]
238 See Documentation/scsi/aic79xx.txt.
239
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 amijoy.map= [HW,JOY] Amiga joystick support
241 Map of devices attached to JOY0DAT and JOY1DAT
242 Format: <a>,<b>
243 See also Documentation/kernel/input/joystick.txt
244
245 analog.map= [HW,JOY] Analog joystick and gamepad support
246 Specifies type or capabilities of an analog joystick
247 connected to one of 16 gameports
248 Format: <type1>,<type2>,..<type16>
249
Randy Dunlapa9913042005-10-23 12:57:11 -0700250 apc= [HW,SPARC]
251 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 Format: noidle
253 Disable APC CPU standby support. SPARCstation-Fox does
254 not play well with APC CPU idle - disable it if you have
255 APC and your system crashes randomly.
256
Randy Dunlapa9913042005-10-23 12:57:11 -0700257 apic= [APIC,i386] Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 Format: { quiet (default) | verbose | debug }
259 Change the amount of debugging information output
260 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700261
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 apm= [APM] Advanced Power Management
263 See header of arch/i386/kernel/apm.c.
264
265 applicom= [HW]
266 Format: <mem>,<irq>
Randy Dunlapa9913042005-10-23 12:57:11 -0700267
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
269 Format: <io>,<irq>,<nodeID>
270
271 ataflop= [HW,M68k]
272
273 atarimouse= [HW,MOUSE] Atari Mouse
274
275 atascsi= [HW,SCSI] Atari SCSI
276
277 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
278 EzKey and similar keyboards
279
280 atkbd.reset= [HW] Reset keyboard during initialization
281
Randy Dunlapa9913042005-10-23 12:57:11 -0700282 atkbd.set= [HW] Select keyboard code set
283 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
285 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
286 keyboards
287
288 atkbd.softraw= [HW] Choose between synthetic and real raw mode
289 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700290
291 atkbd.softrepeat= [HW]
292 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
294 autotest [IA64]
295
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 aztcd= [HW,CD] Aztech CD268 CDROM driver
297 Format: <io>,0x79 (?)
298
299 baycom_epp= [HW,AX25]
300 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
303 Format: <io>,<mode>
304 See header of drivers/net/hamradio/baycom_par.c.
305
Randy Dunlapa9913042005-10-23 12:57:11 -0700306 baycom_ser_fdx= [HW,AX25]
307 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 Format: <io>,<irq>,<mode>[,<baud>]
309 See header of drivers/net/hamradio/baycom_ser_fdx.c.
310
Randy Dunlapa9913042005-10-23 12:57:11 -0700311 baycom_ser_hdx= [HW,AX25]
312 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 Format: <io>,<irq>,<mode>
314 See header of drivers/net/hamradio/baycom_ser_hdx.c.
315
316 blkmtd_device= [HW,MTD]
317 blkmtd_erasesz=
318 blkmtd_ro=
319 blkmtd_bs=
320 blkmtd_count=
321
322 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700323 bttv.radio= Most important insmod options are available as
324 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
326 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
327
328 BusLogic= [HW,SCSI]
329 See drivers/scsi/BusLogic.c, comment before function
330 BusLogic_ParseDriverOptions().
331
332 c101= [NET] Moxa C101 synchronous serial card
333
334 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
335 Sometimes CPU hardware bugs make them report the cache
336 size incorrectly. The kernel will attempt work arounds
337 to fix known problems, but for some CPUs it is not
338 possible to determine what the correct size should be.
339 This option provides an override for these situations.
340
341 cdu31a= [HW,CD]
342 Format: <io>,<irq>[,PAS]
343 See header of drivers/cdrom/cdu31a.c.
344
345 chandev= [HW,NET] Generic channel device initialisation
346
347 checkreqprot [SELINUX] Set initial checkreqprot flag value.
348 Format: { "0" | "1" }
349 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700350 0 -- check protection applied by kernel (includes
351 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 1 -- check protection requested by application.
353 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700354 Value can be changed at runtime via
355 /selinux/checkreqprot.
356
john stultz734efb42006-06-26 00:25:05 -0700357 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
358 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200359 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700360 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200361 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 Format: { pit | tsc | cyclone | pmtmr }
363
Andi Kleenf9262c12006-03-08 17:57:25 -0800364 disable_8254_timer
365 enable_8254_timer
366 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
367 over the 8254 in addition to over the IO-APIC. The
368 kernel tries to set a sensible default.
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 hpet= [IA-32,HPET] option to disable HPET and use PIT.
371 Format: disable
372
373 cm206= [HW,CD]
374 Format: { auto | [<io>,][<irq>] }
375
376 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700377 Format:
378 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
381 Format: <io>[,<irq>]
382
Randy Dunlapa9913042005-10-23 12:57:11 -0700383 com90xx= [HW,NET]
384 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 Format: <io>[,<irq>[,<memstart>]]
386
387 condev= [HW,S390] console device
388 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700389
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 console= [KNL] Output console device and options.
391
392 tty<n> Use the virtual console device <n>.
393
394 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800395 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800397 the form "bbbbpnf", where "bbbb" is the baud rate,
398 "p" is parity ("n", "o", or "e"), "n" is number of
399 bits, and "f" is flow control ("r" for RTS or
400 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800402 See Documentation/serial-console.txt for more
403 information. See
404 Documentation/networking/netconsole.txt for an
405 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406
407 uart,io,<addr>[,options]
408 uart,mmio,<addr>[,options]
409 Start an early, polled-mode console on the 8250/16550
410 UART at the specified I/O port or MMIO address,
411 switching to the matching ttyS device later. The
412 options are the same as for ttyS, above.
413
414 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700415 Format:
416 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417
418 cpia_pp= [HW,PPT]
419 Format: { parport<nr> | auto | none }
420
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700421 crashkernel=nn[KMG]@ss[KMG]
422 [KNL] Reserve a chunk of physical memory to
423 hold a kernel to switch to with kexec on panic.
424
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 cs4232= [HW,OSS]
426 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
427
428 cs89x0_dma= [HW,NET]
429 Format: <dma>
430
431 cs89x0_media= [HW,NET]
432 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700433
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
Randy Dunlapa9913042005-10-23 12:57:11 -0700435
436 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 See header of drivers/s390/block/dasd_devmap.c.
438
439 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
440 (one device per port)
441 Format: <port#>,<type>
442 See also Documentation/input/joystick-parport.txt
443
444 debug [KNL] Enable kernel debugging (events log level).
445
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700446 debug_locks_verbose=
447 [KNL] verbose self-tests
448 Format=<0|1>
449 Print debugging info while doing the locking API
450 self-tests.
451 We default to 0 (no extra messages), setting it to
452 1 will print _a lot_ more information - normally
453 only useful to kernel developers.
454
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 decnet= [HW,NET]
456 Format: <area>[,<node>]
457 See also Documentation/networking/decnet.txt.
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 dhash_entries= [KNL]
460 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700461
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 digi= [HW,SERIAL]
463 IO parameters + enable/disable command.
464
465 digiepca= [HW,SERIAL]
466 See drivers/char/README.epca and
467 Documentation/digiepca.txt.
468
469 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
470 support available.
471 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
472
473 dmasound= [HW,OSS] Sound subsystem buffers
474
475 dscc4.setup= [NET]
476
477 dtc3181e= [HW,SCSI]
478
Randy Dunlapa9913042005-10-23 12:57:11 -0700479 earlyprintk= [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 earlyprintk=vga
481 earlyprintk=serial[,ttySn[,baudrate]]
482
Randy Dunlapa9913042005-10-23 12:57:11 -0700483 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 takes over.
485
486 Only vga or serial at a time, not both.
487
488 Currently only ttyS0 and ttyS1 are supported.
489
490 Interaction with the standard serial driver is not
491 very good.
492
493 The VGA output is eventually overwritten by the real
494 console.
495
496 eata= [HW,SCSI]
497
Len Brown53f11d42005-12-05 16:46:36 -0500498 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
499 Format: <int>
500 0: polling mode
501 non-0: interrupt mode (default)
502
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 eda= [HW,PS2]
504
505 edb= [HW,PS2]
506
507 edd= [EDD]
508 Format: {"of[f]" | "sk[ipmbr]"}
509 See comment in arch/i386/boot/edd.S
510
Randy Dunlapa9913042005-10-23 12:57:11 -0700511 eicon= [HW,ISDN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 Format: <id>,<membase>,<irq>
513
514 eisa_irq_edge= [PARISC,HW]
515 See header of drivers/parisc/eisa.c.
516
517 elanfreq= [IA-32]
518 See comment before function elanfreq_setup() in
519 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
520
521 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800522 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700523 See Documentation/block/as-iosched.txt and
524 Documentation/block/deadline-iosched.txt for details.
525
Vivek Goyalaac04b32006-01-09 20:51:47 -0800526 elfcorehdr= [IA-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700527 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800528 image elf header. Generally kexec loader will
529 pass this option to capture kernel.
530 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531
532 enforcing [SELINUX] Set initial enforcing status.
533 Format: {"0" | "1"}
534 See security/selinux/Kconfig help text.
535 0 -- permissive (log only, no denials).
536 1 -- enforcing (deny and log).
537 Default value is 0.
538 Value can be changed at runtime via /selinux/enforce.
539
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 es1371= [HW,OSS]
541 Format: <spdif>,[<nomix>,[<amplifier>]]
542 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 ether= [HW,NET] Ethernet cards parameters
545 This option is obsoleted by the "netdev=" option, which
546 has equivalent usage. See its documentation for details.
547
548 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
549 Format: <io>[,<irq>]
550
Akinobu Mitade1ba092006-12-08 02:39:42 -0800551 failslab=
552 fail_page_alloc=
553 fail_make_request=[KNL]
554 General fault injection mechanism.
555 Format: <interval>,<probability>,<space>,<times>
556 See also /Documentation/fault-injection/.
557
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 fd_mcs= [HW,SCSI]
559 See header of drivers/scsi/fd_mcs.c.
560
561 fdomain= [HW,SCSI]
562 See header of drivers/scsi/fdomain.c.
563
564 floppy= [HW]
565 See Documentation/floppy.txt.
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 gamecon.map[2|3]=
568 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
569 support via parallel port (up to 5 devices per port)
570 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
571 See also Documentation/input/joystick-parport.txt
572
573 gamma= [HW,DRM]
574
575 gdth= [HW,SCSI]
576 See header of drivers/scsi/gdth.c.
577
578 gpt [EFI] Forces disk with valid GPT signature but
579 invalid Protective MBR to be treated as GPT.
580
581 gscd= [HW,CD]
582 Format: <io>
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 gvp11= [HW,SCSI]
585
586 hashdist= [KNL,NUMA] Large hashes allocated during boot
587 are distributed across NUMA nodes. Defaults on
588 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700589 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
591 hcl= [IA-64] SGI's Hardware Graph compatibility layer
592
593 hd= [EIDE] (E)IDE hard drive subsystem geometry
594 Format: <cyl>,<head>,<sect>
595
596 hd?= [HW] (E)IDE subsystem
597 hd?lun= See Documentation/ide.txt.
598
599 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
600 size of <nn>. This works even on boxes that have no
601 highmem otherwise. This also works to reduce highmem
602 size on bigger boxes.
603
604 hisax= [HW,ISDN]
605 See Documentation/isdn/README.HiSax.
606
607 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200610 i8042.dumbkbd [HW] Pretend that controller can only read data from
611 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 (Don't attempt to blink the leds)
613 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500614 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 i8042.nomux [HW] Don't check presence of an active multiplexing
616 controller
617 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
618 controllers
619 i8042.panicblink=
620 [HW] Frequency with which keyboard LEDs should blink
621 when kernel panics (default is 0.5 sec)
622 i8042.reset [HW] Reset the controller during init and cleanup
623 i8042.unlock [HW] Unlock (ignore) the keylock
624
625 i810= [HW,DRM]
626
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700627 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
628 indicates that the driver is running on unsupported
629 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
631 does not match list of supported models.
632 i8k.power_status
633 [HW] Report power status in /proc/i8k
634 (disabled by default)
635 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
636 capability is set.
637
638 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
639 See Documentation/mca.txt.
640
641 icn= [HW,ISDN]
642 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
643
644 ide= [HW] (E)IDE subsystem
645 Format: ide=nodma or ide=doubler or ide=reverse
646 See Documentation/ide.txt.
647
648 ide?= [HW] (E)IDE subsystem
649 Format: ide?=noprobe or chipset specific parameters.
650 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700651
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
653 See Documentation/ide.txt.
654
655 idle= [HW]
656 Format: idle=poll or idle=halt
Randy Dunlapa9913042005-10-23 12:57:11 -0700657
Ingo Molnar792908222006-12-06 20:40:51 -0800658 ignore_loglevel [KNL]
659 Ignore loglevel setting - this will print /all/
660 kernel messages to the console. Useful for debugging.
661
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 ihash_entries= [KNL]
663 Set number of hash buckets for inode cache.
664
665 in2000= [HW,SCSI]
666 See header of drivers/scsi/in2000.c.
667
668 init= [KNL]
669 Format: <full_path>
670 Run specified binary instead of /sbin/init as init
671 process.
672
673 initcall_debug [KNL] Trace initcalls as they are executed. Useful
674 for working out where the kernel is dying during
675 startup.
676
677 initrd= [BOOT] Specify the location of the initial ramdisk
678
679 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
680 Format: <irq>
681
Jesse Barnes2bd0fa32005-12-13 03:05:03 -0500682 combined_mode= [HW] control which driver uses IDE ports in combined
683 mode: legacy IDE driver, libata, or both
684 (in the libata case, libata.atapi_enabled=1 may be
685 useful as well). Note that using the ide or libata
686 options may affect your device naming (e.g. by
687 changing hdc to sdb).
688 Format: combined (default), ide, or libata
689
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 inttest= [IA64]
691
692 io7= [HW] IO7 for Marvel based alpha systems
693 See comment before marvel_specify_io7 in
694 arch/alpha/kernel/core_marvel.c.
695
696 ip= [IP_PNP]
697 See Documentation/nfsroot.txt.
698
699 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
700 See comment before ip2_setup() in drivers/char/ip2.c.
701
702 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
703 See header of drivers/scsi/ips.c.
704
Simon Horman72c4a132006-09-13 19:57:18 -0700705 ports= [IP_VS_FTP] IPVS ftp helper module
706 Default is 21.
707 Up to 8 (IP_VS_APP_MAX_PORTS) ports
708 may be specified.
709 Format: <port>,<port>....
710
Alan Cox200803d2005-06-28 20:45:18 -0700711 irqfixup [HW]
712 When an interrupt is not handled search all handlers
713 for it. Intended to get systems with badly broken
714 firmware running.
715
716 irqpoll [HW]
717 When an interrupt is not handled search all handlers
718 for it. Also check all handlers each timer
719 interrupt. Intended to get systems with badly broken
720 firmware running.
721
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700723 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724
725 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800726 Format:
727 <cpu number>,...,<cpu number>
728 or
729 <cpu number>-<cpu number> (must be a positive range in ascending order)
730 or a mixture
731 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 This option can be used to specify one or more CPUs
733 to isolate from the general SMP balancing and scheduling
734 algorithms. The only way to move a process onto or off
735 an "isolated" CPU is via the CPU affinity syscalls.
736 <cpu number> begins at 0 and the maximum value is
737 "number of CPUs in system - 1".
738
739 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700740 alternative -- manually setting the CPU mask of all
741 tasks in the system -- can cause problems and
742 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743
744 isp16= [HW,CD]
745 Format: <io>,<irq>,<dma>,<setup>
746
Randy Dunlapa9913042005-10-23 12:57:11 -0700747 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
749 js= [HW,JOY] Analog joystick
750 See Documentation/input/joystick.txt.
751
752 keepinitrd [HW,ARM]
753
Randy Dunlapa9913042005-10-23 12:57:11 -0700754 kstack=N [IA-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 in oops dumps.
756
757 l2cr= [PPC]
758
Randy Dunlapa9913042005-10-23 12:57:11 -0700759 lapic [IA-32,APIC] Enable the local APIC even if BIOS
760 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761
762 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
763 Format: addr:<io>,irq:<irq>
764
Randy Dunlapa9913042005-10-23 12:57:11 -0700765 llsc*= [IA64] See function print_params() in
766 arch/ia64/sn/kernel/llsc4.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767
768 load_ramdisk= [RAM] List of ramdisks to load from floppy
769 See Documentation/ramdisk.txt.
770
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800771 lockd.nlm_grace_period=P [NFS] Assign grace period.
772 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800774 lockd.nlm_tcpport=N [NFS] Assign TCP port.
775 Format: <integer>
776
777 lockd.nlm_timeout=T [NFS] Assign timeout value.
778 Format: <integer>
779
780 lockd.nlm_udpport=M [NFS] Assign UDP port.
781 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782
783 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
784 Format: <irq>
785
786 loglevel= All Kernel Messages with a loglevel smaller than the
787 console loglevel will be printed to the console. It can
788 also be changed with klogd or other programs. The
789 loglevels are defined as follows:
790
791 0 (KERN_EMERG) system is unusable
792 1 (KERN_ALERT) action must be taken immediately
793 2 (KERN_CRIT) critical conditions
794 3 (KERN_ERR) error conditions
795 4 (KERN_WARNING) warning conditions
796 5 (KERN_NOTICE) normal but significant condition
797 6 (KERN_INFO) informational
798 7 (KERN_DEBUG) debug-level messages
799
800 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700801 Format: { n | nk | nM }
802 n must be a power of two. The default size
803 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
805 lp=0 [LP] Specify parallel ports to use, e.g,
806 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
807 lp=reset first parallel port). 'lp=0' disables the
808 lp=auto printer driver. 'lp=reset' (which can be
809 specified in addition to the ports) causes
810 attached printers to be reset. Using
811 lp=port1,port2,... specifies the parallel ports
812 to associate lp devices with, starting with
813 lp0. A port specification may be 'none' to skip
814 that lp device, or a parport name such as
815 'parport0'. Specifying 'lp=auto' instead of a
816 port specification list means that device IDs
817 from each port should be examined, to see if
818 an IEEE 1284-compliant printer is attached; if
819 so, the driver will manage that printer.
820 See also header of drivers/char/lp.c.
821
822 lpj=n [KNL]
823 Sets loops_per_jiffy to given constant, thus avoiding
824 time-consuming boot-time autodetection (up to 250 ms per
825 CPU). 0 enables autodetection (default). To determine
826 the correct value for your kernel, boot with normal
827 autodetection and see what value is printed. Note that
828 on SMP systems the preset will be applied to all CPUs,
829 which is likely to cause problems if your CPUs need
830 significantly divergent settings. An incorrect value
831 will cause delays in the kernel to be wrong, leading to
832 unpredictable I/O errors and other breakage. Although
833 unlikely, in the extreme case this might damage your
834 hardware.
835
836 ltpc= [NET]
837 Format: <io>,<irq>,<dma>
838
Randy Dunlapa9913042005-10-23 12:57:11 -0700839 mac5380= [HW,SCSI] Format:
840 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
Randy Dunlapa9913042005-10-23 12:57:11 -0700842 mac53c9x= [HW,SCSI] Format:
843 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
Randy Dunlapa9913042005-10-23 12:57:11 -0700845 machvec= [IA64] Force the use of a particular machine-vector
846 (machvec) in a generic kernel.
847 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848
Randy Dunlapa9913042005-10-23 12:57:11 -0700849 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 be mounted
851 Format: <1-256>
852
853 maxcpus= [SMP] Maximum number of processors that an SMP kernel
854 should make use of
855
Bob Picco2b2c3752005-06-29 18:00:00 -0700856 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
857 equal to this physical address is ignored.
858
Randy Dunlapa9913042005-10-23 12:57:11 -0700859 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 Should be between 1 and 2^32-1.
861
862 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -0700863 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 Should be between 1 and 16384.
865
866 mca-pentium [BUGS=IA-32]
867
868 mcatest= [IA-64]
869
870 mcd= [HW,CD]
871 Format: <port>,<irq>,<mitsumi_bug_93_wait>
872
873 mcdx= [HW,CD]
874
875 mce [IA-32] Machine Check Exception
876
877 md= [HW] RAID subsystems devices and level
878 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700879
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 mdacon= [MDA]
881 Format: <first>,<last>
882 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -0700883
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
885 Amount of memory to be used when the kernel is not able
886 to see the whole system memory or for test.
887 [IA-32] Use together with memmap= to avoid physical
888 address space collisions. Without memmap= PCI devices
889 could be placed at addresses belonging to unused RAM.
890
891 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
892 memory.
893
akpm@osdl.org69cda7b2006-01-09 20:51:46 -0800894 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 E820 memory map, as specified by the user.
896 Such memmap=exactmap lines can be constructed based on
897 BIOS output or other requirements. See the memmap=nn@ss
898 option description.
899
900 memmap=nn[KMG]@ss[KMG]
901 [KNL] Force usage of a specific region of memory
902 Region of memory to be used, from ss to ss+nn.
903
904 memmap=nn[KMG]#ss[KMG]
905 [KNL,ACPI] Mark specific memory as ACPI data.
906 Region of memory to be used, from ss to ss+nn.
907
908 memmap=nn[KMG]$ss[KMG]
909 [KNL,ACPI] Mark specific memory as reserved.
910 Region of memory to be used, from ss to ss+nn.
911
912 meye.*= [HW] Set MotionEye Camera parameters
913 See Documentation/video4linux/meye.txt.
914
915 mga= [HW,DRM]
916
akpm@osdl.org198e2f12006-01-12 01:05:30 -0800917 migration_cost=
918 [KNL,SMP] debug: override scheduler migration costs
919 Format: <level-1-usecs>,<level-2-usecs>,...
920 This debugging option can be used to override the
921 default scheduler migration cost matrix. The numbers
922 are indexed by 'CPU domain distance'.
923 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
924 box will set up an intra-core migration cost of
925 1 msec, an inter-core migration cost of 2 msecs,
926 and an inter-node migration cost of 3 msecs.
927
928 WARNING: using the wrong values here can break
929 scheduler performance, so it's only for scheduler
930 development purposes, not production environments.
931
932 migration_debug=
933 [KNL,SMP] migration cost auto-detect verbosity
934 Format=<0|1|2>
935 If a system's migration matrix reported at bootup
936 seems erroneous then this option can be used to
937 increase verbosity of the detection process.
938 We default to 0 (no extra messages), 1 will print
939 some more information, and 2 will be really
940 verbose (probably only useful if you also have a
941 serial console attached to the system).
942
943 migration_factor=
944 [KNL,SMP] multiply/divide migration costs by a factor
945 Format=<percent>
946 This debug option can be used to proportionally
947 increase or decrease the auto-detected migration
948 costs for all entries of the migration matrix.
949 E.g. migration_factor=150 will increase migration
950 costs by 50%. (and thus the scheduler will be less
951 eager migrating cache-hot tasks)
952 migration_factor=80 will decrease migration costs
953 by 20%. (thus the scheduler will be more eager to
954 migrate tasks)
955
956 WARNING: using the wrong values here can break
957 scheduler performance, so it's only for scheduler
958 development purposes, not production environments.
959
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960 mousedev.tap_time=
961 [MOUSE] Maximum time between finger touching and
962 leaving touchpad surface for touch to be considered
963 a tap and be reported as a left button click (for
964 touchpads working in absolute mode only).
965 Format: <msecs>
966 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
967 reporting absolute coordinates, such as tablets
968 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
969 reporting absolute coordinates, such as tablets
970
971 mpu401= [HW,OSS]
972 Format: <io>,<irq>
973
974 MTD_Partition= [MTD]
975 Format: <name>,<region-number>,<size>,<offset>
976
Randy Dunlapa9913042005-10-23 12:57:11 -0700977 MTD_Region= [MTD] Format:
978 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979
980 mtdparts= [MTD]
981 See drivers/mtd/cmdline.c.
982
983 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -0700984 [HW] Make the MicroTouch USB driver use raw coordinates
985 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986
987 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
988
989 NCR_D700= [HW,SCSI]
990 See header of drivers/scsi/NCR_D700.c.
991
992 ncr5380= [HW,SCSI]
993
994 ncr53c400= [HW,SCSI]
995
996 ncr53c400a= [HW,SCSI]
997
998 ncr53c406a= [HW,SCSI]
999
1000 ncr53c8xx= [HW,SCSI]
1001
1002 netdev= [NET] Network devices parameters
1003 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1004 Note that mem_start is often overloaded to mean
1005 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001006 This usage is only documented in each driver source
1007 file if at all.
1008
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 nfsaddrs= [NFS]
1010 See Documentation/nfsroot.txt.
1011
1012 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1013 See Documentation/nfsroot.txt.
1014
Trond Myklebusta72b4422006-01-03 09:55:41 +01001015 nfs.callback_tcpport=
1016 [NFS] set the TCP port on which the NFSv4 callback
1017 channel should listen.
1018
Trond Myklebust58df0952006-01-03 09:55:57 +01001019 nfs.idmap_cache_timeout=
1020 [NFS] set the maximum lifetime for idmapper cache
1021 entries.
1022
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1024
1025 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1026 emulation library even if a 387 maths coprocessor
1027 is present.
1028
Paul Menage3395ee02006-12-06 20:32:16 -08001029 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1030 the slab allocator. Saves per-node memory, but will
1031 impact performance on real NUMA hardware.
1032
Randy Dunlapa9913042005-10-23 12:57:11 -07001033 noalign [KNL,ARM]
1034
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 noapic [SMP,APIC] Tells the kernel to not make use of any
1036 IOAPICs that may be present in the system.
1037
1038 noasync [HW,M68K] Disables async and sync negotiation for
1039 all devices.
1040
1041 nobats [PPC] Do not use BATs for mapping kernel lowmem
1042 on "Classic" PPC cores.
1043
1044 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001045
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001046 nodelayacct [KNL] Disable per-task delay accounting
1047
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1049
1050 noexec [IA-64]
1051
Randy Dunlapa9913042005-10-23 12:57:11 -07001052 noexec [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 noexec=on: enable non-executable mappings (default)
1054 noexec=off: disable nn-executable mappings
1055
Chuck Ebbert4f886512006-03-23 02:59:34 -08001056 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1057 register save and restore. The kernel will only save
1058 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059
1060 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001061
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1063 instruction doesn't work correctly and not to
1064 use it.
1065
1066 nohalt [IA-64] Tells the kernel not to use the power saving
1067 function PAL_HALT_LIGHT when idle. This increases
1068 power-consumption. On the positive side, it reduces
1069 interrupt wake-up latency, which may improve performance
1070 in certain environments such as networked servers or
1071 real-time systems.
1072
Zachary Amsden8542b202006-12-07 02:14:09 +01001073 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1074
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 noirqdebug [IA-32] Disables the code which attempts to detect and
1076 disable unhandled interrupt sources.
1077
Zachary Amsden8542b202006-12-07 02:14:09 +01001078 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1079 broken timer IRQ sources.
1080
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 noisapnp [ISAPNP] Disables ISA PnP code.
1082
1083 noinitrd [RAM] Tells the kernel not to load any configured
1084 initial RAM disk.
1085
1086 nointroute [IA-64]
1087
1088 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1089
1090 noltlbs [PPC] Do not use large page/tlb entries for kernel
1091 lowmem mapping on PPC40x.
1092
Horms312f1f02006-02-22 09:57:55 +09001093 nomca [IA-64] Disable machine check abort handling
1094
Hormsabe37e52006-04-01 01:36:09 +02001095 nomce [IA-32] Machine Check Exception
1096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 noresidual [PPC] Don't use residual data on PReP machines.
1098
Randy Dunlapa9913042005-10-23 12:57:11 -07001099 noresume [SWSUSP] Disables resume and restores original swap
1100 space.
1101
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 no-scroll [VGA] Disables scrollback.
1103 This is required for the Braillex ib80-piezo Braille
1104 reader made by F.H. Papenmeier (Germany).
1105
1106 nosbagart [IA-64]
1107
Chuck Ebbert4f886512006-03-23 02:59:34 -08001108 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1109
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1111
1112 nosync [HW,M68K] Disables sync negotiation for all devices.
1113
1114 notsc [BUGS=IA-32] Disable Time Stamp Counter
1115
1116 nousb [USB] Disable the USB subsystem
1117
1118 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001119
Dave Jonesa61c2d72006-01-07 23:18:19 +00001120 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1121
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 opl3= [HW,OSS]
1123 Format: <io>
1124
Randy Dunlapa9913042005-10-23 12:57:11 -07001125 opl3sa2= [HW,OSS] Format:
1126 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1127
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 oprofile.timer= [HW]
1129 Use timer interrupt instead of performance counters
1130
1131 optcd= [HW,CD]
1132 Format: <io>
1133
1134 osst= [HW,SCSI] SCSI Tape Driver
1135 Format: <buffer_size>,<write_threshold>
1136 See also Documentation/scsi/st.txt.
1137
1138 panic= [KNL] Kernel behaviour on panic
1139 Format: <timeout>
1140
1141 parkbd.port= [HW] Parallel port number the keyboard adapter is
1142 connected to, default is 0.
1143 Format: <parport#>
1144 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1145 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001146 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147
Randy Dunlapa9913042005-10-23 12:57:11 -07001148 parport= [HW,PPT] Specify parallel ports. 0 disables.
1149 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1150 Use 'auto' to force the driver to use any
1151 IRQ/DMA settings detected (the default is to
1152 ignore detected IRQ/DMA settings because of
1153 possible conflicts). You can specify the base
1154 address, IRQ, and DMA settings; IRQ and DMA
1155 should be numbers, or 'auto' (for using detected
1156 settings on that particular port), or 'nofifo'
1157 (to avoid using a FIFO even if it is detected).
1158 Parallel ports are assigned in the order they
1159 are specified on the command line, starting
1160 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161
Randy Dunlapa9913042005-10-23 12:57:11 -07001162 parport_init_mode= [HW,PPT]
1163 Configure VIA parallel port to operate in
1164 a specific mode. This is necessary on Pegasos
1165 computer where firmware has no options for setting
1166 up parallel port mode and sets it to spp.
1167 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168 Format: [spp|ps2|epp|ecp|ecpepp]
1169
Randy Dunlapa9913042005-10-23 12:57:11 -07001170 pas2= [HW,OSS] Format:
1171 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1172
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 pas16= [HW,SCSI]
1174 See header of drivers/scsi/pas16.c.
1175
Andrew Mortondd287792006-03-23 03:00:57 -08001176 pause_on_oops=
1177 Halt all CPUs after the first oops has been printed for
1178 the specified number of seconds. This is to be used if
1179 your oopses keep scrolling off the screen.
1180
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 pcbit= [HW,ISDN]
1182
1183 pcd. [PARIDE]
1184 See header of drivers/block/paride/pcd.c.
1185 See also Documentation/paride.txt.
1186
Randy Dunlapa9913042005-10-23 12:57:11 -07001187 pci=option[,option...] [PCI] various PCI subsystem options:
1188 off [IA-32] don't probe for the PCI bus
1189 bios [IA-32] force use of PCI BIOS, don't access
1190 the hardware directly. Use this if your machine
1191 has a non-standard PCI host bridge.
1192 nobios [IA-32] disallow use of PCI BIOS, only direct
1193 hardware access methods are allowed. Use this
1194 if you experience crashes upon bootup and you
1195 suspect they are caused by the BIOS.
1196 conf1 [IA-32] Force use of PCI Configuration
1197 Mechanism 1.
1198 conf2 [IA-32] Force use of PCI Configuration
1199 Mechanism 2.
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001200 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1201 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001202 nomsi [MSI] If the PCI_MSI kernel config parameter is
1203 enabled, this kernel boot option can be used to
1204 disable the use of MSI interrupts system-wide.
Randy Dunlapa9913042005-10-23 12:57:11 -07001205 nosort [IA-32] Don't sort PCI devices according to
1206 order given by the PCI BIOS. This sorting is
1207 done to get a device order compatible with
1208 older kernels.
1209 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1210 routing table. These calls are known to be buggy
1211 on several machines and they hang the machine
1212 when used, but on other computers it's the only
1213 way to get the interrupt routing table. Try
1214 this option if the kernel is unable to allocate
1215 IRQs or discover secondary PCI buses on your
1216 motherboard.
1217 rom [IA-32] Assign address space to expansion ROMs.
1218 Use with caution as certain devices share
1219 address decoders between ROMs and other
1220 resources.
1221 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1222 assigned automatically to PCI devices. You can
1223 make the kernel exclude IRQs of your ISA cards
1224 this way.
jayalk@intworks.biz120bb422005-03-21 20:20:42 -08001225 pirqaddr=0xAAAAA [IA-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001226 of the PIRQ table (normally generated
1227 by the BIOS) if it is outside the
1228 F0000h-100000h range.
1229 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1230 useful if the kernel is unable to find your
1231 secondary buses and you want to tell it
1232 explicitly which ones they are.
1233 assign-busses [IA-32] Always assign all PCI bus
1234 numbers ourselves, overriding
1235 whatever the firmware may have done.
1236 usepirqmask [IA-32] Honor the possible IRQ mask stored
1237 in the BIOS $PIR table. This is needed on
1238 some systems with broken BIOSes, notably
1239 some HP Pavilion N5400 and Omnibook XE3
1240 notebooks. This will have no effect if ACPI
1241 IRQ routing is enabled.
1242 noacpi [IA-32] Do not use ACPI for IRQ routing
1243 or for PCI scanning.
1244 routeirq Do IRQ routing for all PCI devices.
1245 This is normally done in pci_enable_device(),
1246 so this option is a temporary workaround
1247 for broken drivers that don't call it.
1248 firmware [ARM] Do not re-enumerate the bus but instead
1249 just use the configuration from the
1250 bootloader. This is currently used on
1251 IXP2000 systems where the bus has to be
1252 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001253 noearly [X86] Don't do any early type 1 scanning.
1254 This might help on some broken boards which
1255 machine check when some devices' config space
1256 is read. But various workarounds are disabled
1257 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001258 bfsort Sort PCI devices into breadth-first order.
1259 This sorting is done to get a device
1260 order compatible with older (<= 2.4) kernels.
1261 nobfsort Don't sort PCI devices into breadth-first order.
1262
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 pcmv= [HW,PCMCIA] BadgePAD 4
1264
1265 pd. [PARIDE]
1266 See Documentation/paride.txt.
1267
1268 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1269 boot time.
1270 Format: { 0 | 1 }
1271 See arch/parisc/kernel/pdc_chassis.c
1272
1273 pf. [PARIDE]
1274 See Documentation/paride.txt.
1275
1276 pg. [PARIDE]
1277 See Documentation/paride.txt.
1278
1279 pirq= [SMP,APIC] Manual mp-table setup
1280 See Documentation/i386/IO-APIC.txt.
1281
1282 plip= [PPT,NET] Parallel port network link
1283 Format: { parport<nr> | timid | 0 }
1284 See also Documentation/parport.txt.
1285
1286 pnpacpi= [ACPI]
1287 { off }
1288
1289 pnpbios= [ISAPNP]
1290 { on | off | curr | res | no-curr | no-res }
1291
1292 pnp_reserve_irq=
1293 [ISAPNP] Exclude IRQs for the autoconfiguration
1294
1295 pnp_reserve_dma=
1296 [ISAPNP] Exclude DMAs for the autoconfiguration
1297
1298 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001299 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300
1301 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001302 [ISAPNP] Exclude memory regions for the
1303 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 Ranges are in pairs (memory base and size).
1305
1306 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001307 Format: [schedule,]<number>
1308 Param: "schedule" - profile schedule points.
1309 Param: <number> - step/bucket size as a power of 2 for
1310 statistical time based profiling.
Ingo Molnarece8a682006-12-06 20:37:24 -08001311 Param: "sleep" - profile D-state sleeping (millisecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312
Randy Dunlapa9913042005-10-23 12:57:11 -07001313 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 Limit processor to maximum C-state
1315 max_cstate=9 overrides any DMI blacklist limit.
1316
Len Brown41c0d862005-12-28 12:43:51 -05001317 processor.nocst [HW,ACPI]
1318 Ignore the _CST method to determine C-states,
1319 instead using the legacy FADT method
1320
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1322 before loading.
1323 See Documentation/ramdisk.txt.
1324
Randy Dunlapa9913042005-10-23 12:57:11 -07001325 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1326 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1328 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001329 psmouse.resetafter= [HW,MOUSE]
1330 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331 (0 = never).
1332 psmouse.resolution=
1333 [HW,MOUSE] Set desired mouse resolution, in dpi.
1334 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001335 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 0 = disabled, 1 = enabled (default).
1337
1338 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001339 Format:
1340 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341
1342 pt. [PARIDE]
1343 See Documentation/paride.txt.
1344
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001345 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001346
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 r128= [HW,DRM]
1348
1349 raid= [HW,RAID]
1350 See Documentation/md.txt.
1351
1352 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1353 See Documentation/ramdisk.txt.
1354
Randy Dunlapa9913042005-10-23 12:57:11 -07001355 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001357
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1359 New name for the ramdisk parameter.
1360 See Documentation/ramdisk.txt.
1361
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001362 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1363 RCU callbacks to process in one batch.
1364
1365 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1366 RCU callbacks over which batch limiting is disabled.
1367
1368 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1369 RCU callbacks below which batch limiting is re-enabled.
1370
Olof Johanssonffdfc402005-09-06 15:17:19 -07001371 rdinit= [KNL]
1372 Format: <full_path>
1373 Run specified binary instead of /init from the ramdisk,
1374 used for early userspace startup. See initrd.
1375
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1377 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Michael Opdenackerf3e299f2006-10-03 23:19:24 +02001378 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
1380 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1381
Zachary Amsden461a9af2006-09-25 23:32:25 -07001382 reservetop= [IA-32]
1383 Format: nn[KMG]
1384 Reserves a hole at the top of the kernel virtual
1385 address space.
1386
Vivek Goyal7e962872006-09-27 01:50:44 -07001387 reset_devices [KNL] Force drivers to reset the underlying device
1388 during initialization.
1389
Randy Dunlapa9913042005-10-23 12:57:11 -07001390 resume= [SWSUSP]
1391 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001393 resume_offset= [SWSUSP]
1394 Specify the offset from the beginning of the partition
1395 given by "resume=" at which the swap header is located,
1396 in <PAGE_SIZE> units (needed only for swap files).
1397 See Documentation/power/swsusp-and-swap-files.txt
1398
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 rhash_entries= [KNL,NET]
1400 Set number of hash buckets for route cache
1401
1402 riscom8= [HW,SERIAL]
1403 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1404
1405 ro [KNL] Mount root device read-only on boot
1406
1407 root= [KNL] Root filesystem
1408
1409 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1410 mount the root filesystem
1411
1412 rootflags= [KNL] Set root filesystem mount option string
1413
1414 rootfstype= [KNL] Set root filesystem type
1415
1416 rw [KNL] Mount root device read-write on boot
1417
1418 S [KNL] Run init in single mode
1419
1420 sa1100ir [NET]
1421 See drivers/net/irda/sa1100_ir.c.
1422
1423 sb= [HW,OSS]
1424 Format: <io>,<irq>,<dma>,<dma2>
1425
1426 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001427
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 sbpcd= [HW,CD] Soundblaster CD adapter
1429 Format: <io>,<type>
1430 See a comment before function sbpcd_setup() in
1431 drivers/cdrom/sbpcd.c.
1432
1433 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1434 Format: <io>[,<timeout>[,<isapnp>]]
1435
1436 scsi_debug_*= [SCSI]
1437 See drivers/scsi/scsi_debug.c.
1438
1439 scsi_default_dev_flags=
1440 [SCSI] SCSI default device flags
1441 Format: <integer>
1442
1443 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1444 Format: <vendor>:<model>:<flags>
1445 (flags are integer value)
1446
1447 scsi_logging= [SCSI]
1448
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001449 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1450 discovered. async scans them in kernel threads,
1451 allowing boot to proceed. none ignores them, expecting
1452 user space to do the scan.
1453
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454 selinux [SELINUX] Disable or enable SELinux at boot time.
1455 Format: { "0" | "1" }
1456 See security/selinux/Kconfig help text.
1457 0 -- disable.
1458 1 -- enable.
1459 Default value is set via kernel config option.
1460 If enabled at boot time, /selinux/disable can be used
1461 later to disable prior to initial policy load.
1462
James Morris4e5ab4c2006-06-09 00:33:33 -07001463 selinux_compat_net =
1464 [SELINUX] Set initial selinux_compat_net flag value.
1465 Format: { "0" | "1" }
1466 0 -- use new secmark-based packet controls
1467 1 -- use legacy packet controls
1468 Default value is 0 (preferred).
1469 Value can be changed at runtime via
1470 /selinux/compat_net.
1471
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 serialnumber [BUGS=IA-32]
1473
Randy Dunlapa9913042005-10-23 12:57:11 -07001474 sg_def_reserved_size= [SCSI]
1475
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476 shapers= [NET]
1477 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 sim710= [SCSI,HW]
1480 See header of drivers/scsi/sim710.c.
1481
1482 simeth= [IA-64]
1483 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001484
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 sjcd= [HW,CD]
1486 Format: <io>,<irq>,<dma>
1487 See header of drivers/cdrom/sjcd.c.
1488
1489 slram= [HW,MTD]
1490
1491 smart2= [HW]
1492 Format: <io1>[,<io2>[,...,<io8>]]
1493
1494 snd-ad1816a= [HW,ALSA]
1495
1496 snd-ad1848= [HW,ALSA]
1497
1498 snd-ali5451= [HW,ALSA]
1499
1500 snd-als100= [HW,ALSA]
1501
1502 snd-als4000= [HW,ALSA]
1503
1504 snd-azt2320= [HW,ALSA]
1505
1506 snd-cmi8330= [HW,ALSA]
1507
1508 snd-cmipci= [HW,ALSA]
1509
1510 snd-cs4231= [HW,ALSA]
1511
1512 snd-cs4232= [HW,ALSA]
1513
1514 snd-cs4236= [HW,ALSA]
1515
1516 snd-cs4281= [HW,ALSA]
1517
1518 snd-cs46xx= [HW,ALSA]
1519
1520 snd-dt019x= [HW,ALSA]
1521
1522 snd-dummy= [HW,ALSA]
1523
1524 snd-emu10k1= [HW,ALSA]
1525
1526 snd-ens1370= [HW,ALSA]
1527
1528 snd-ens1371= [HW,ALSA]
1529
1530 snd-es968= [HW,ALSA]
1531
1532 snd-es1688= [HW,ALSA]
1533
1534 snd-es18xx= [HW,ALSA]
1535
1536 snd-es1938= [HW,ALSA]
1537
1538 snd-es1968= [HW,ALSA]
1539
1540 snd-fm801= [HW,ALSA]
1541
1542 snd-gusclassic= [HW,ALSA]
1543
1544 snd-gusextreme= [HW,ALSA]
1545
1546 snd-gusmax= [HW,ALSA]
1547
1548 snd-hdsp= [HW,ALSA]
1549
1550 snd-ice1712= [HW,ALSA]
1551
1552 snd-intel8x0= [HW,ALSA]
1553
1554 snd-interwave= [HW,ALSA]
1555
1556 snd-interwave-stb=
1557 [HW,ALSA]
1558
1559 snd-korg1212= [HW,ALSA]
1560
1561 snd-maestro3= [HW,ALSA]
1562
1563 snd-mpu401= [HW,ALSA]
1564
1565 snd-mtpav= [HW,ALSA]
1566
1567 snd-nm256= [HW,ALSA]
1568
1569 snd-opl3sa2= [HW,ALSA]
1570
1571 snd-opti92x-ad1848=
1572 [HW,ALSA]
1573
1574 snd-opti92x-cs4231=
1575 [HW,ALSA]
1576
1577 snd-opti93x= [HW,ALSA]
1578
1579 snd-pmac= [HW,ALSA]
1580
1581 snd-rme32= [HW,ALSA]
1582
1583 snd-rme96= [HW,ALSA]
1584
1585 snd-rme9652= [HW,ALSA]
1586
1587 snd-sb8= [HW,ALSA]
1588
1589 snd-sb16= [HW,ALSA]
1590
1591 snd-sbawe= [HW,ALSA]
1592
1593 snd-serial= [HW,ALSA]
1594
1595 snd-sgalaxy= [HW,ALSA]
1596
1597 snd-sonicvibes= [HW,ALSA]
1598
1599 snd-sun-amd7930=
1600 [HW,ALSA]
1601
1602 snd-sun-cs4231= [HW,ALSA]
1603
1604 snd-trident= [HW,ALSA]
1605
1606 snd-usb-audio= [HW,ALSA,USB]
1607
1608 snd-via82xx= [HW,ALSA]
1609
1610 snd-virmidi= [HW,ALSA]
1611
1612 snd-wavefront= [HW,ALSA]
1613
1614 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001615
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 sonycd535= [HW,CD]
1617 Format: <io>[,<irq>]
1618
1619 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1620 See Documentation/sonypi.txt
1621
1622 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1623 See Documentation/specialix.txt.
1624
1625 spia_io_base= [HW,MTD]
1626 spia_fio_base=
1627 spia_pedr=
1628 spia_peddr=
1629
1630 sscape= [HW,OSS]
1631 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001632
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1634 See Documentation/scsi/st.txt.
1635
1636 st0x= [HW,SCSI]
1637 See header of drivers/scsi/seagate.c.
1638
1639 sti= [PARISC,HW]
1640 Format: <num>
1641 Set the STI (builtin display/keyboard on the HP-PARISC
1642 machines) console (graphic card) which should be used
1643 as the initial boot-console.
1644 See also comment in drivers/video/console/sticore.c.
1645
1646 sti_font= [HW]
1647 See comment in drivers/video/console/sticore.c.
1648
1649 stifb= [HW]
1650 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001653
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654 switches= [HW,M68k]
1655
1656 sym53c416= [HW,SCSI]
1657 See header of drivers/scsi/sym53c416.c.
1658
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001659 sysrq_always_enabled
1660 [KNL]
1661 Ignore sysrq setting - this boot parameter will
1662 neutralize any effect of /proc/sys/kernel/sysrq.
1663 Useful for debugging.
1664
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 t128= [HW,SCSI]
1666 See header of drivers/scsi/t128.c.
1667
1668 tdfx= [HW,DRM]
1669
1670 thash_entries= [KNL,NET]
1671 Set number of hash buckets for TCP connection
1672
1673 time Show timing data prefixed to each printk message line
1674
john stultz734efb42006-06-26 00:25:05 -07001675 clocksource= [GENERIC_TIME] Override the default clocksource
1676 Override the default clocksource and use the clocksource
1677 with the name specified.
1678
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 tipar.timeout= [HW,PPT]
1680 Set communications timeout in tenths of a second
1681 (default 15).
1682
1683 tipar.delay= [HW,PPT]
1684 Set inter-bit delay in microseconds (default 10).
1685
1686 tmc8xx= [HW,SCSI]
1687 See header of drivers/scsi/seagate.c.
1688
1689 tmscsim= [HW,SCSI]
1690 See comment before function dc390_setup() in
1691 drivers/scsi/tmscsim.c.
1692
1693 tp720= [HW,PS2]
1694
1695 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001696 Format:
1697 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1698
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 tsdev.xres= [TS] Horizontal screen resolution.
1700 tsdev.yres= [TS] Vertical screen resolution.
1701
Randy Dunlapa9913042005-10-23 12:57:11 -07001702 turbografx.map[2|3]= [HW,JOY]
1703 TurboGraFX parallel port interface
1704 Format:
1705 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706 See also Documentation/input/joystick-parport.txt
1707
1708 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1709 See header of drivers/scsi/u14-34f.c.
1710
1711 uart401= [HW,OSS]
1712 Format: <io>,<irq>
1713
1714 uart6850= [HW,OSS]
1715 Format: <io>,<irq>
1716
Alan Stern5f8364b2006-12-05 16:29:55 -05001717 uhci-hcd.ignore_oc=
1718 [USB] Ignore overcurrent events (default N).
1719 Some badly-designed motherboards generate lots of
1720 bogus events, for ports that aren't wired to
1721 anything. Set this parameter to avoid log spamming.
1722 Note that genuine overcurrent events won't be
1723 reported either.
1724
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 usbhid.mousepoll=
1726 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07001727
Ingo Molnare6e54942006-06-27 02:53:50 -07001728 vdso= [IA-32]
1729 vdso=1: enable VDSO (default)
1730 vdso=0: disable VDSO mapping
1731
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 video= [FB] Frame buffer configuration
1733 See Documentation/fb/modedb.txt.
1734
1735 vga= [BOOT,IA-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07001736 See Documentation/i386/boot.txt and
1737 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738 Use vga=ask for menu.
1739 This is actually a boot loader parameter; the value is
1740 passed to the kernel using a special protocol.
1741
Randy Dunlapa9913042005-10-23 12:57:11 -07001742 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 size of <nn>. This can be used to increase the
1744 minimum size (128MB on x86). It can also be used to
1745 decrease the size and leave more room for directly
1746 mapped kernel RAM.
1747
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001748 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1749 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001751 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1752 Format: <command>
1753
1754 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1755 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07001756
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 waveartist= [HW,OSS]
1758 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07001759
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 wd33c93= [HW,SCSI]
1761 See header of drivers/scsi/wd33c93.c.
1762
1763 wd7000= [HW,SCSI]
1764 See header of drivers/scsi/wd7000.c.
1765
1766 wdt= [WDT] Watchdog
1767 See Documentation/watchdog/watchdog.txt.
1768
1769 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1770 xd_geo= See header of drivers/block/xd.c.
1771
1772 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001773 Format:
1774 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775
Andi Kleena62eaf12006-02-16 23:41:58 +01001776 norandmaps Don't use address space randomization
1777 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1778
Jan Beulich6d0185e2006-12-07 02:14:13 +01001779 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1780 This is useful to get more information why
1781 you got a "dwarf2 unwinder stuck"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782
Randy Dunlapa9913042005-10-23 12:57:11 -07001783______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784
1785TODO:
1786
1787 Add documentation for ALSA options.
1788 Add more DRM drivers.