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Stefan Richter0ee9d712006-04-01 01:42:29 +02001 Kernel Parameters
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 ~~~~~~~~~~~~~~~~~
3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Stefan Richtera901ebb2006-04-01 01:43:18 +020020This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
Stefan Richter6585fa82006-04-01 01:44:30 +020027The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070038 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070047 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070051 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070060 MSI Message Signaled Interrupts (PCI).
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070064 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PARIDE The ParIDE subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
79 Documentation/scsi/.
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090082 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 SMP The kernel is an SMP kernel.
84 SPARC Sparc architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070085 SWSUSP Software suspend is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 TS Appropriate touchscreen support is enabled.
87 USB USB support is enabled.
88 USBHID USB Human Interface Device support is enabled.
89 V4L Video For Linux support is enabled.
90 VGA The VGA console has been enabled.
91 VT Virtual terminal support is enabled.
92 WDT Watchdog support is enabled.
93 XT IBM PC/XT MFM hard disk support is enabled.
94 X86-64 X86-64 architecture is enabled.
95 More X86-64 boot options can be found in
96 Documentation/x86_64/boot-options.txt .
97
98In addition, the following text indicates that the option:
99
100 BUGS= Relates to possible processor bugs on the said processor.
101 KNL Is a kernel start-up parameter.
102 BOOT Is a boot loader parameter.
103
104Parameters denoted with BOOT are actually interpreted by the boot
105loader, and have no meaning to the kernel directly.
106Do not modify the syntax of boot loader parameters without extreme
107need or coordination with <Documentation/i386/boot.txt>.
108
Karsten Weiss55588702007-02-13 13:26:21 +0100109There are also arch-specific kernel-parameters not documented here.
110See for example <Documentation/x86_64/boot-options.txt>.
111
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
113a trailing = on the name of any parameter states that that parameter will
114be entered as an environment variable, whereas its absence indicates that
115it will appear as a kernel argument readable via /proc/cmdline by programs
116running once the system is up.
117
jens m. noedler9c4751f2006-09-29 02:00:27 -0700118The number of kernel parameters is not limited, but the length of the
119complete command line (parameters including spaces etc.) is limited to
120a fixed number of characters. This limit depends on the architecture
121and is between 256 and 4096 characters. It is defined in the file
122./include/asm/setup.h as COMMAND_LINE_SIZE.
123
124
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 53c7xx= [HW,SCSI] Amiga SCSI controllers
126 See header of drivers/scsi/53c7xx.c.
127 See also Documentation/scsi/ncr53c7xx.txt.
128
Bernhard Walle03d926f2007-03-06 02:29:44 -0800129 acpi= [HW,ACPI,X86-64,i386]
130 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700131 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 force -- enable ACPI if default was off
133 off -- disable ACPI if default was on
134 noirq -- do not use ACPI for IRQ routing
135 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700136 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 strictly ACPI specification compliant.
138
139 See also Documentation/pm.txt, pci=noacpi
140
Len Browna1fdcc02007-03-11 03:26:14 -0400141 acpi_apic_instance= [ACPI, IOAPIC]
142 Format: <int>
143 2: use 2nd APIC table, if available
144 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400145 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400146
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 acpi_sleep= [HW,ACPI] Sleep options
148 Format: { s3_bios, s3_mode }
149 See Documentation/power/video.txt
Randy Dunlapa9913042005-10-23 12:57:11 -0700150
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700152 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
Randy Dunlapa9913042005-10-23 12:57:11 -0700154 acpi_irq_balance [HW,ACPI]
155 ACPI will balance active IRQs
156 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
Randy Dunlapa9913042005-10-23 12:57:11 -0700158 acpi_irq_nobalance [HW,ACPI]
159 ACPI will not move active IRQs (default)
160 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Randy Dunlapa9913042005-10-23 12:57:11 -0700162 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
163 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 Format: <irq>,<irq>...
165
Randy Dunlapa9913042005-10-23 12:57:11 -0700166 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 Format: <irq>,<irq>...
168
Len Browna1f9e652006-01-25 23:47:36 -0500169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
170 Format: To spoof as Windows 98: ="Microsoft Windows"
171
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 acpi_osi= [HW,ACPI] empty param disables _OSI
173
174 acpi_serialize [HW,ACPI] force serialization of AML methods
175
176 acpi_skip_timer_override [HW,ACPI]
177 Recognize and ignore IRQ0/pin2 Interrupt Override.
178 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100179 acpi_use_timer_override [HW,ACPI}
180 Use timer override. For some broken Nvidia NF5 boards
181 that require a timer override, but don't have
182 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
184 acpi_dbg_layer= [HW,ACPI]
185 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700186 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 1: enable, 0: disable. It is useful for boot time
188 debugging. After system has booted up, it can be set
189 via /proc/acpi/debug_layer.
190
191 acpi_dbg_level= [HW,ACPI]
192 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700193 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 1: enable, 0: disable. It is useful for boot time
195 debugging. After system has booted up, it can be set
196 via /proc/acpi/debug_level.
197
198 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
199
Luming Yu30e332f2005-08-12 00:31:00 -0400200 acpi_generic_hotkey [HW,ACPI]
201 Allow consolidated generic hotkey driver to
Randy Dunlapa9913042005-10-23 12:57:11 -0700202 override platform specific driver.
Luming Yu30e332f2005-08-12 00:31:00 -0400203 See also Documentation/acpi-hotkey.txt.
204
john stultz5d0cf412006-06-26 00:25:12 -0700205 acpi_pm_good [IA-32,X86-64]
206 Override the pmtimer bug detection: force the kernel
207 to assume that this machine's pmtimer latches its value
208 and always returns good values.
209
Chuck Ebbert66759a02005-09-12 18:49:25 +0200210 enable_timer_pin_1 [i386,x86-64]
211 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700212 Can be useful to work around chipset bugs
213 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200214 The kernel tries to set a reasonable default.
215
216 disable_timer_pin_1 [i386,x86-64]
217 Disable PIN 1 of APIC timer
218 Can be useful to work around chipset bugs.
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 ad1816= [HW,OSS]
221 Format: <io>,<irq>,<dma>,<dma2>
222 See also Documentation/sound/oss/AD1816.
223
224 ad1848= [HW,OSS]
225 Format: <io>,<irq>,<dma>,<dma2>,<type>
226
227 adlib= [HW,OSS]
228 Format: <io>
Randy Dunlapa9913042005-10-23 12:57:11 -0700229
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 advansys= [HW,SCSI]
231 See header of drivers/scsi/advansys.c.
232
233 advwdt= [HW,WDT] Advantech WDT
234 Format: <iostart>,<iostop>
235
236 aedsp16= [HW,OSS] Audio Excel DSP 16
237 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
238 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700239
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 aha152x= [HW,SCSI]
241 See Documentation/scsi/aha152x.txt.
242
243 aha1542= [HW,SCSI]
244 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
245
246 aic7xxx= [HW,SCSI]
247 See Documentation/scsi/aic7xxx.txt.
248
249 aic79xx= [HW,SCSI]
250 See Documentation/scsi/aic79xx.txt.
251
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 amijoy.map= [HW,JOY] Amiga joystick support
253 Map of devices attached to JOY0DAT and JOY1DAT
254 Format: <a>,<b>
255 See also Documentation/kernel/input/joystick.txt
256
257 analog.map= [HW,JOY] Analog joystick and gamepad support
258 Specifies type or capabilities of an analog joystick
259 connected to one of 16 gameports
260 Format: <type1>,<type2>,..<type16>
261
Randy Dunlapa9913042005-10-23 12:57:11 -0700262 apc= [HW,SPARC]
263 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 Format: noidle
265 Disable APC CPU standby support. SPARCstation-Fox does
266 not play well with APC CPU idle - disable it if you have
267 APC and your system crashes randomly.
268
Randy Dunlapa9913042005-10-23 12:57:11 -0700269 apic= [APIC,i386] Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 Format: { quiet (default) | verbose | debug }
271 Change the amount of debugging information output
272 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700273
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 apm= [APM] Advanced Power Management
275 See header of arch/i386/kernel/apm.c.
276
277 applicom= [HW]
278 Format: <mem>,<irq>
Randy Dunlapa9913042005-10-23 12:57:11 -0700279
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
281 Format: <io>,<irq>,<nodeID>
282
283 ataflop= [HW,M68k]
284
285 atarimouse= [HW,MOUSE] Atari Mouse
286
287 atascsi= [HW,SCSI] Atari SCSI
288
289 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
290 EzKey and similar keyboards
291
292 atkbd.reset= [HW] Reset keyboard during initialization
293
Randy Dunlapa9913042005-10-23 12:57:11 -0700294 atkbd.set= [HW] Select keyboard code set
295 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
297 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
298 keyboards
299
300 atkbd.softraw= [HW] Choose between synthetic and real raw mode
301 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700302
303 atkbd.softrepeat= [HW]
304 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306 autotest [IA64]
307
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 aztcd= [HW,CD] Aztech CD268 CDROM driver
309 Format: <io>,0x79 (?)
310
311 baycom_epp= [HW,AX25]
312 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700313
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
315 Format: <io>,<mode>
316 See header of drivers/net/hamradio/baycom_par.c.
317
Randy Dunlapa9913042005-10-23 12:57:11 -0700318 baycom_ser_fdx= [HW,AX25]
319 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 Format: <io>,<irq>,<mode>[,<baud>]
321 See header of drivers/net/hamradio/baycom_ser_fdx.c.
322
Randy Dunlapa9913042005-10-23 12:57:11 -0700323 baycom_ser_hdx= [HW,AX25]
324 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 Format: <io>,<irq>,<mode>
326 See header of drivers/net/hamradio/baycom_ser_hdx.c.
327
328 blkmtd_device= [HW,MTD]
329 blkmtd_erasesz=
330 blkmtd_ro=
331 blkmtd_bs=
332 blkmtd_count=
333
334 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700335 bttv.radio= Most important insmod options are available as
336 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
338 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
339
340 BusLogic= [HW,SCSI]
341 See drivers/scsi/BusLogic.c, comment before function
342 BusLogic_ParseDriverOptions().
343
344 c101= [NET] Moxa C101 synchronous serial card
345
346 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
347 Sometimes CPU hardware bugs make them report the cache
348 size incorrectly. The kernel will attempt work arounds
349 to fix known problems, but for some CPUs it is not
350 possible to determine what the correct size should be.
351 This option provides an override for these situations.
352
353 cdu31a= [HW,CD]
354 Format: <io>,<irq>[,PAS]
355 See header of drivers/cdrom/cdu31a.c.
356
357 chandev= [HW,NET] Generic channel device initialisation
358
359 checkreqprot [SELINUX] Set initial checkreqprot flag value.
360 Format: { "0" | "1" }
361 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700362 0 -- check protection applied by kernel (includes
363 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 1 -- check protection requested by application.
365 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700366 Value can be changed at runtime via
367 /selinux/checkreqprot.
368
john stultz734efb42006-06-26 00:25:05 -0700369 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
370 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200371 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700372 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200373 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 Format: { pit | tsc | cyclone | pmtmr }
375
Chuck Ebbert86c41832007-02-13 13:26:25 +0100376 code_bytes [IA32] How many bytes of object code to print in an
377 oops report.
378 Range: 0 - 8192
379 Default: 64
380
Andi Kleenf9262c12006-03-08 17:57:25 -0800381 disable_8254_timer
382 enable_8254_timer
383 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
384 over the 8254 in addition to over the IO-APIC. The
385 kernel tries to set a sensible default.
386
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 hpet= [IA-32,HPET] option to disable HPET and use PIT.
388 Format: disable
389
390 cm206= [HW,CD]
391 Format: { auto | [<io>,][<irq>] }
392
393 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700394 Format:
395 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
397 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
398 Format: <io>[,<irq>]
399
Randy Dunlapa9913042005-10-23 12:57:11 -0700400 com90xx= [HW,NET]
401 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 Format: <io>[,<irq>[,<memstart>]]
403
404 condev= [HW,S390] console device
405 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700406
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 console= [KNL] Output console device and options.
408
409 tty<n> Use the virtual console device <n>.
410
411 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800412 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800414 the form "bbbbpnf", where "bbbb" is the baud rate,
415 "p" is parity ("n", "o", or "e"), "n" is number of
416 bits, and "f" is flow control ("r" for RTS or
417 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800419 See Documentation/serial-console.txt for more
420 information. See
421 Documentation/networking/netconsole.txt for an
422 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423
424 uart,io,<addr>[,options]
425 uart,mmio,<addr>[,options]
426 Start an early, polled-mode console on the 8250/16550
427 UART at the specified I/O port or MMIO address,
428 switching to the matching ttyS device later. The
429 options are the same as for ttyS, above.
430
431 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700432 Format:
433 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434
435 cpia_pp= [HW,PPT]
436 Format: { parport<nr> | auto | none }
437
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700438 crashkernel=nn[KMG]@ss[KMG]
439 [KNL] Reserve a chunk of physical memory to
440 hold a kernel to switch to with kexec on panic.
441
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 cs4232= [HW,OSS]
443 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
444
445 cs89x0_dma= [HW,NET]
446 Format: <dma>
447
448 cs89x0_media= [HW,NET]
449 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700450
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
Randy Dunlapa9913042005-10-23 12:57:11 -0700452
453 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 See header of drivers/s390/block/dasd_devmap.c.
455
456 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
457 (one device per port)
458 Format: <port#>,<type>
459 See also Documentation/input/joystick-parport.txt
460
461 debug [KNL] Enable kernel debugging (events log level).
462
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700463 debug_locks_verbose=
464 [KNL] verbose self-tests
465 Format=<0|1>
466 Print debugging info while doing the locking API
467 self-tests.
468 We default to 0 (no extra messages), setting it to
469 1 will print _a lot_ more information - normally
470 only useful to kernel developers.
471
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 decnet= [HW,NET]
473 Format: <area>[,<node>]
474 See also Documentation/networking/decnet.txt.
475
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 dhash_entries= [KNL]
477 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700478
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 digi= [HW,SERIAL]
480 IO parameters + enable/disable command.
481
482 digiepca= [HW,SERIAL]
483 See drivers/char/README.epca and
484 Documentation/digiepca.txt.
485
486 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
487 support available.
488 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
489
490 dmasound= [HW,OSS] Sound subsystem buffers
491
492 dscc4.setup= [NET]
493
494 dtc3181e= [HW,SCSI]
495
Paul Mundte523d932007-02-28 18:30:01 +0900496 earlyprintk= [IA-32,X86-64,SH]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 earlyprintk=vga
498 earlyprintk=serial[,ttySn[,baudrate]]
499
Randy Dunlapa9913042005-10-23 12:57:11 -0700500 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 takes over.
502
503 Only vga or serial at a time, not both.
504
505 Currently only ttyS0 and ttyS1 are supported.
506
507 Interaction with the standard serial driver is not
508 very good.
509
510 The VGA output is eventually overwritten by the real
511 console.
512
513 eata= [HW,SCSI]
514
Len Brown53f11d42005-12-05 16:46:36 -0500515 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
516 Format: <int>
517 0: polling mode
518 non-0: interrupt mode (default)
519
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 eda= [HW,PS2]
521
522 edb= [HW,PS2]
523
524 edd= [EDD]
525 Format: {"of[f]" | "sk[ipmbr]"}
526 See comment in arch/i386/boot/edd.S
527
Randy Dunlapa9913042005-10-23 12:57:11 -0700528 eicon= [HW,ISDN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 Format: <id>,<membase>,<irq>
530
531 eisa_irq_edge= [PARISC,HW]
532 See header of drivers/parisc/eisa.c.
533
534 elanfreq= [IA-32]
535 See comment before function elanfreq_setup() in
536 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
537
538 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800539 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700540 See Documentation/block/as-iosched.txt and
541 Documentation/block/deadline-iosched.txt for details.
542
Vivek Goyalaac04b32006-01-09 20:51:47 -0800543 elfcorehdr= [IA-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700544 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800545 image elf header. Generally kexec loader will
546 pass this option to capture kernel.
547 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
549 enforcing [SELINUX] Set initial enforcing status.
550 Format: {"0" | "1"}
551 See security/selinux/Kconfig help text.
552 0 -- permissive (log only, no denials).
553 1 -- enforcing (deny and log).
554 Default value is 0.
555 Value can be changed at runtime via /selinux/enforce.
556
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 es1371= [HW,OSS]
558 Format: <spdif>,[<nomix>,[<amplifier>]]
559 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700560
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 ether= [HW,NET] Ethernet cards parameters
562 This option is obsoleted by the "netdev=" option, which
563 has equivalent usage. See its documentation for details.
564
565 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
566 Format: <io>[,<irq>]
567
Akinobu Mitade1ba092006-12-08 02:39:42 -0800568 failslab=
569 fail_page_alloc=
570 fail_make_request=[KNL]
571 General fault injection mechanism.
572 Format: <interval>,<probability>,<space>,<times>
573 See also /Documentation/fault-injection/.
574
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 fd_mcs= [HW,SCSI]
576 See header of drivers/scsi/fd_mcs.c.
577
578 fdomain= [HW,SCSI]
579 See header of drivers/scsi/fdomain.c.
580
581 floppy= [HW]
582 See Documentation/floppy.txt.
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 gamecon.map[2|3]=
585 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
586 support via parallel port (up to 5 devices per port)
587 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
588 See also Documentation/input/joystick-parport.txt
589
590 gamma= [HW,DRM]
591
592 gdth= [HW,SCSI]
593 See header of drivers/scsi/gdth.c.
594
595 gpt [EFI] Forces disk with valid GPT signature but
596 invalid Protective MBR to be treated as GPT.
597
598 gscd= [HW,CD]
599 Format: <io>
600
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 gvp11= [HW,SCSI]
602
603 hashdist= [KNL,NUMA] Large hashes allocated during boot
604 are distributed across NUMA nodes. Defaults on
605 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700606 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607
608 hcl= [IA-64] SGI's Hardware Graph compatibility layer
609
610 hd= [EIDE] (E)IDE hard drive subsystem geometry
611 Format: <cyl>,<head>,<sect>
612
613 hd?= [HW] (E)IDE subsystem
614 hd?lun= See Documentation/ide.txt.
615
616 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
617 size of <nn>. This works even on boxes that have no
618 highmem otherwise. This also works to reduce highmem
619 size on bigger boxes.
620
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800621 highres= [KNL] Enable/disable high resolution timer mode.
622 Valid parameters: "on", "off"
623 Default: "on"
624
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 hisax= [HW,ISDN]
626 See Documentation/isdn/README.HiSax.
627
628 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200631 i8042.dumbkbd [HW] Pretend that controller can only read data from
632 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 (Don't attempt to blink the leds)
634 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500635 i8042.nokbd [HW] Don't check/create keyboard port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 i8042.nomux [HW] Don't check presence of an active multiplexing
637 controller
638 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
639 controllers
640 i8042.panicblink=
641 [HW] Frequency with which keyboard LEDs should blink
642 when kernel panics (default is 0.5 sec)
643 i8042.reset [HW] Reset the controller during init and cleanup
644 i8042.unlock [HW] Unlock (ignore) the keylock
645
646 i810= [HW,DRM]
647
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700648 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
649 indicates that the driver is running on unsupported
650 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
652 does not match list of supported models.
653 i8k.power_status
654 [HW] Report power status in /proc/i8k
655 (disabled by default)
656 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
657 capability is set.
658
659 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
660 See Documentation/mca.txt.
661
662 icn= [HW,ISDN]
663 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
664
665 ide= [HW] (E)IDE subsystem
666 Format: ide=nodma or ide=doubler or ide=reverse
667 See Documentation/ide.txt.
668
669 ide?= [HW] (E)IDE subsystem
670 Format: ide?=noprobe or chipset specific parameters.
671 See Documentation/ide.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700672
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
674 See Documentation/ide.txt.
675
676 idle= [HW]
677 Format: idle=poll or idle=halt
Randy Dunlapa9913042005-10-23 12:57:11 -0700678
Ingo Molnar792908222006-12-06 20:40:51 -0800679 ignore_loglevel [KNL]
680 Ignore loglevel setting - this will print /all/
681 kernel messages to the console. Useful for debugging.
682
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 ihash_entries= [KNL]
684 Set number of hash buckets for inode cache.
685
686 in2000= [HW,SCSI]
687 See header of drivers/scsi/in2000.c.
688
689 init= [KNL]
690 Format: <full_path>
691 Run specified binary instead of /sbin/init as init
692 process.
693
694 initcall_debug [KNL] Trace initcalls as they are executed. Useful
695 for working out where the kernel is dying during
696 startup.
697
698 initrd= [BOOT] Specify the location of the initial ramdisk
699
700 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
701 Format: <irq>
702
Jesse Barnes2bd0fa32005-12-13 03:05:03 -0500703 combined_mode= [HW] control which driver uses IDE ports in combined
704 mode: legacy IDE driver, libata, or both
705 (in the libata case, libata.atapi_enabled=1 may be
706 useful as well). Note that using the ide or libata
707 options may affect your device naming (e.g. by
708 changing hdc to sdb).
709 Format: combined (default), ide, or libata
710
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 inttest= [IA64]
712
713 io7= [HW] IO7 for Marvel based alpha systems
714 See comment before marvel_specify_io7 in
715 arch/alpha/kernel/core_marvel.c.
716
717 ip= [IP_PNP]
718 See Documentation/nfsroot.txt.
719
720 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
721 See comment before ip2_setup() in drivers/char/ip2.c.
722
723 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
724 See header of drivers/scsi/ips.c.
725
Simon Horman72c4a132006-09-13 19:57:18 -0700726 ports= [IP_VS_FTP] IPVS ftp helper module
727 Default is 21.
728 Up to 8 (IP_VS_APP_MAX_PORTS) ports
729 may be specified.
730 Format: <port>,<port>....
731
Alan Cox200803d2005-06-28 20:45:18 -0700732 irqfixup [HW]
733 When an interrupt is not handled search all handlers
734 for it. Intended to get systems with badly broken
735 firmware running.
736
737 irqpoll [HW]
738 When an interrupt is not handled search all handlers
739 for it. Also check all handlers each timer
740 interrupt. Intended to get systems with badly broken
741 firmware running.
742
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700744 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745
746 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800747 Format:
748 <cpu number>,...,<cpu number>
749 or
750 <cpu number>-<cpu number> (must be a positive range in ascending order)
751 or a mixture
752 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 This option can be used to specify one or more CPUs
754 to isolate from the general SMP balancing and scheduling
755 algorithms. The only way to move a process onto or off
756 an "isolated" CPU is via the CPU affinity syscalls.
757 <cpu number> begins at 0 and the maximum value is
758 "number of CPUs in system - 1".
759
760 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700761 alternative -- manually setting the CPU mask of all
762 tasks in the system -- can cause problems and
763 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765 isp16= [HW,CD]
766 Format: <io>,<irq>,<dma>,<setup>
767
Randy Dunlapa9913042005-10-23 12:57:11 -0700768 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769
770 js= [HW,JOY] Analog joystick
771 See Documentation/input/joystick.txt.
772
773 keepinitrd [HW,ARM]
774
Randy Dunlapa9913042005-10-23 12:57:11 -0700775 kstack=N [IA-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 in oops dumps.
777
778 l2cr= [PPC]
779
Randy Dunlapa9913042005-10-23 12:57:11 -0700780 lapic [IA-32,APIC] Enable the local APIC even if BIOS
781 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782
Linus Torvalds2e7c2832007-03-23 11:32:31 -0700783 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +0100784 C2 power state.
785
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
787 Format: addr:<io>,irq:<irq>
788
Randy Dunlapa9913042005-10-23 12:57:11 -0700789 llsc*= [IA64] See function print_params() in
790 arch/ia64/sn/kernel/llsc4.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791
792 load_ramdisk= [RAM] List of ramdisks to load from floppy
793 See Documentation/ramdisk.txt.
794
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800795 lockd.nlm_grace_period=P [NFS] Assign grace period.
796 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
Randy Dunlapa6b25b62006-01-14 13:21:19 -0800798 lockd.nlm_tcpport=N [NFS] Assign TCP port.
799 Format: <integer>
800
801 lockd.nlm_timeout=T [NFS] Assign timeout value.
802 Format: <integer>
803
804 lockd.nlm_udpport=M [NFS] Assign UDP port.
805 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806
807 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
808 Format: <irq>
809
810 loglevel= All Kernel Messages with a loglevel smaller than the
811 console loglevel will be printed to the console. It can
812 also be changed with klogd or other programs. The
813 loglevels are defined as follows:
814
815 0 (KERN_EMERG) system is unusable
816 1 (KERN_ALERT) action must be taken immediately
817 2 (KERN_CRIT) critical conditions
818 3 (KERN_ERR) error conditions
819 4 (KERN_WARNING) warning conditions
820 5 (KERN_NOTICE) normal but significant condition
821 6 (KERN_INFO) informational
822 7 (KERN_DEBUG) debug-level messages
823
824 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -0700825 Format: { n | nk | nM }
826 n must be a power of two. The default size
827 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828
829 lp=0 [LP] Specify parallel ports to use, e.g,
830 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
831 lp=reset first parallel port). 'lp=0' disables the
832 lp=auto printer driver. 'lp=reset' (which can be
833 specified in addition to the ports) causes
834 attached printers to be reset. Using
835 lp=port1,port2,... specifies the parallel ports
836 to associate lp devices with, starting with
837 lp0. A port specification may be 'none' to skip
838 that lp device, or a parport name such as
839 'parport0'. Specifying 'lp=auto' instead of a
840 port specification list means that device IDs
841 from each port should be examined, to see if
842 an IEEE 1284-compliant printer is attached; if
843 so, the driver will manage that printer.
844 See also header of drivers/char/lp.c.
845
846 lpj=n [KNL]
847 Sets loops_per_jiffy to given constant, thus avoiding
848 time-consuming boot-time autodetection (up to 250 ms per
849 CPU). 0 enables autodetection (default). To determine
850 the correct value for your kernel, boot with normal
851 autodetection and see what value is printed. Note that
852 on SMP systems the preset will be applied to all CPUs,
853 which is likely to cause problems if your CPUs need
854 significantly divergent settings. An incorrect value
855 will cause delays in the kernel to be wrong, leading to
856 unpredictable I/O errors and other breakage. Although
857 unlikely, in the extreme case this might damage your
858 hardware.
859
860 ltpc= [NET]
861 Format: <io>,<irq>,<dma>
862
Randy Dunlapa9913042005-10-23 12:57:11 -0700863 mac5380= [HW,SCSI] Format:
864 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865
Randy Dunlapa9913042005-10-23 12:57:11 -0700866 mac53c9x= [HW,SCSI] Format:
867 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868
Randy Dunlapa9913042005-10-23 12:57:11 -0700869 machvec= [IA64] Force the use of a particular machine-vector
870 (machvec) in a generic kernel.
871 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872
Randy Dunlapa9913042005-10-23 12:57:11 -0700873 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 be mounted
875 Format: <1-256>
876
877 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Randy Dunlap78f92a82007-02-17 19:58:30 +0100878 should make use of.
879 Using "nosmp" or "maxcpus=0" will disable SMP
880 entirely (the MPS table probe still happens, though).
881 A command-line option of "maxcpus=<NUM>", where <NUM>
882 is an integer greater than 0, limits the maximum number
883 of CPUs activated in SMP mode to <NUM>.
884 Using "maxcpus=1" on an SMP kernel is the trivial
885 case of an SMP kernel with only one CPU.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886
Bob Picco2b2c3752005-06-29 18:00:00 -0700887 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
888 equal to this physical address is ignored.
889
Randy Dunlapa9913042005-10-23 12:57:11 -0700890 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 Should be between 1 and 2^32-1.
892
893 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -0700894 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 Should be between 1 and 16384.
896
897 mca-pentium [BUGS=IA-32]
898
899 mcatest= [IA-64]
900
901 mcd= [HW,CD]
902 Format: <port>,<irq>,<mitsumi_bug_93_wait>
903
904 mcdx= [HW,CD]
905
906 mce [IA-32] Machine Check Exception
907
908 md= [HW] RAID subsystems devices and level
909 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -0700910
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 mdacon= [MDA]
912 Format: <first>,<last>
913 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -0700914
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
916 Amount of memory to be used when the kernel is not able
917 to see the whole system memory or for test.
918 [IA-32] Use together with memmap= to avoid physical
919 address space collisions. Without memmap= PCI devices
920 could be placed at addresses belonging to unused RAM.
921
922 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
923 memory.
924
akpm@osdl.org69cda7b2006-01-09 20:51:46 -0800925 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 E820 memory map, as specified by the user.
927 Such memmap=exactmap lines can be constructed based on
928 BIOS output or other requirements. See the memmap=nn@ss
929 option description.
930
931 memmap=nn[KMG]@ss[KMG]
932 [KNL] Force usage of a specific region of memory
933 Region of memory to be used, from ss to ss+nn.
934
935 memmap=nn[KMG]#ss[KMG]
936 [KNL,ACPI] Mark specific memory as ACPI data.
937 Region of memory to be used, from ss to ss+nn.
938
939 memmap=nn[KMG]$ss[KMG]
940 [KNL,ACPI] Mark specific memory as reserved.
941 Region of memory to be used, from ss to ss+nn.
942
943 meye.*= [HW] Set MotionEye Camera parameters
944 See Documentation/video4linux/meye.txt.
945
946 mga= [HW,DRM]
947
akpm@osdl.org198e2f12006-01-12 01:05:30 -0800948 migration_cost=
949 [KNL,SMP] debug: override scheduler migration costs
950 Format: <level-1-usecs>,<level-2-usecs>,...
951 This debugging option can be used to override the
952 default scheduler migration cost matrix. The numbers
953 are indexed by 'CPU domain distance'.
954 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
955 box will set up an intra-core migration cost of
956 1 msec, an inter-core migration cost of 2 msecs,
957 and an inter-node migration cost of 3 msecs.
958
959 WARNING: using the wrong values here can break
960 scheduler performance, so it's only for scheduler
961 development purposes, not production environments.
962
963 migration_debug=
964 [KNL,SMP] migration cost auto-detect verbosity
965 Format=<0|1|2>
966 If a system's migration matrix reported at bootup
967 seems erroneous then this option can be used to
968 increase verbosity of the detection process.
969 We default to 0 (no extra messages), 1 will print
970 some more information, and 2 will be really
971 verbose (probably only useful if you also have a
972 serial console attached to the system).
973
974 migration_factor=
975 [KNL,SMP] multiply/divide migration costs by a factor
976 Format=<percent>
977 This debug option can be used to proportionally
978 increase or decrease the auto-detected migration
979 costs for all entries of the migration matrix.
980 E.g. migration_factor=150 will increase migration
981 costs by 50%. (and thus the scheduler will be less
982 eager migrating cache-hot tasks)
983 migration_factor=80 will decrease migration costs
984 by 20%. (thus the scheduler will be more eager to
985 migrate tasks)
986
987 WARNING: using the wrong values here can break
988 scheduler performance, so it's only for scheduler
989 development purposes, not production environments.
990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 mousedev.tap_time=
992 [MOUSE] Maximum time between finger touching and
993 leaving touchpad surface for touch to be considered
994 a tap and be reported as a left button click (for
995 touchpads working in absolute mode only).
996 Format: <msecs>
997 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
998 reporting absolute coordinates, such as tablets
999 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1000 reporting absolute coordinates, such as tablets
1001
1002 mpu401= [HW,OSS]
1003 Format: <io>,<irq>
1004
1005 MTD_Partition= [MTD]
1006 Format: <name>,<region-number>,<size>,<offset>
1007
Randy Dunlapa9913042005-10-23 12:57:11 -07001008 MTD_Region= [MTD] Format:
1009 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
1011 mtdparts= [MTD]
1012 See drivers/mtd/cmdline.c.
1013
1014 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001015 [HW] Make the MicroTouch USB driver use raw coordinates
1016 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
1018 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1019
1020 NCR_D700= [HW,SCSI]
1021 See header of drivers/scsi/NCR_D700.c.
1022
1023 ncr5380= [HW,SCSI]
1024
1025 ncr53c400= [HW,SCSI]
1026
1027 ncr53c400a= [HW,SCSI]
1028
1029 ncr53c406a= [HW,SCSI]
1030
1031 ncr53c8xx= [HW,SCSI]
1032
1033 netdev= [NET] Network devices parameters
1034 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1035 Note that mem_start is often overloaded to mean
1036 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001037 This usage is only documented in each driver source
1038 file if at all.
1039
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 nfsaddrs= [NFS]
1041 See Documentation/nfsroot.txt.
1042
1043 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1044 See Documentation/nfsroot.txt.
1045
Trond Myklebusta72b4422006-01-03 09:55:41 +01001046 nfs.callback_tcpport=
1047 [NFS] set the TCP port on which the NFSv4 callback
1048 channel should listen.
1049
Trond Myklebust58df0952006-01-03 09:55:57 +01001050 nfs.idmap_cache_timeout=
1051 [NFS] set the maximum lifetime for idmapper cache
1052 entries.
1053
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1055
1056 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1057 emulation library even if a 387 maths coprocessor
1058 is present.
1059
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -07001060 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1061 when set.
1062 Format: <int>
1063
Paul Menage3395ee02006-12-06 20:32:16 -08001064 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1065 the slab allocator. Saves per-node memory, but will
1066 impact performance on real NUMA hardware.
1067
Randy Dunlapa9913042005-10-23 12:57:11 -07001068 noalign [KNL,ARM]
1069
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 noapic [SMP,APIC] Tells the kernel to not make use of any
1071 IOAPICs that may be present in the system.
1072
1073 noasync [HW,M68K] Disables async and sync negotiation for
1074 all devices.
1075
1076 nobats [PPC] Do not use BATs for mapping kernel lowmem
1077 on "Classic" PPC cores.
1078
1079 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001080
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001081 nodelayacct [KNL] Disable per-task delay accounting
1082
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1084
1085 noexec [IA-64]
1086
Randy Dunlapa9913042005-10-23 12:57:11 -07001087 noexec [IA-32,X86-64]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 noexec=on: enable non-executable mappings (default)
1089 noexec=off: disable nn-executable mappings
1090
Chuck Ebbert4f886512006-03-23 02:59:34 -08001091 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1092 register save and restore. The kernel will only save
1093 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094
1095 nohlt [BUGS=ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1098 instruction doesn't work correctly and not to
1099 use it.
1100
1101 nohalt [IA-64] Tells the kernel not to use the power saving
1102 function PAL_HALT_LIGHT when idle. This increases
1103 power-consumption. On the positive side, it reduces
1104 interrupt wake-up latency, which may improve performance
1105 in certain environments such as networked servers or
1106 real-time systems.
1107
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001108 nohz= [KNL] Boottime enable/disable dynamic ticks
1109 Valid arguments: on, off
1110 Default: on
1111
Zachary Amsden8542b202006-12-07 02:14:09 +01001112 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1113
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 noirqdebug [IA-32] Disables the code which attempts to detect and
1115 disable unhandled interrupt sources.
1116
Zachary Amsden8542b202006-12-07 02:14:09 +01001117 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1118 broken timer IRQ sources.
1119
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 noisapnp [ISAPNP] Disables ISA PnP code.
1121
1122 noinitrd [RAM] Tells the kernel not to load any configured
1123 initial RAM disk.
1124
1125 nointroute [IA-64]
1126
1127 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1128
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001129 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1130
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 noltlbs [PPC] Do not use large page/tlb entries for kernel
1132 lowmem mapping on PPC40x.
1133
Horms312f1f02006-02-22 09:57:55 +09001134 nomca [IA-64] Disable machine check abort handling
1135
Hormsabe37e52006-04-01 01:36:09 +02001136 nomce [IA-32] Machine Check Exception
1137
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 noresidual [PPC] Don't use residual data on PReP machines.
1139
Randy Dunlapa9913042005-10-23 12:57:11 -07001140 noresume [SWSUSP] Disables resume and restores original swap
1141 space.
1142
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 no-scroll [VGA] Disables scrollback.
1144 This is required for the Braillex ib80-piezo Braille
1145 reader made by F.H. Papenmeier (Germany).
1146
1147 nosbagart [IA-64]
1148
Chuck Ebbert4f886512006-03-23 02:59:34 -08001149 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1150
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1152
1153 nosync [HW,M68K] Disables sync negotiation for all devices.
1154
1155 notsc [BUGS=IA-32] Disable Time Stamp Counter
1156
1157 nousb [USB] Disable the USB subsystem
1158
1159 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001160
Dave Jonesa61c2d72006-01-07 23:18:19 +00001161 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1162
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 opl3= [HW,OSS]
1164 Format: <io>
1165
Randy Dunlapa9913042005-10-23 12:57:11 -07001166 opl3sa2= [HW,OSS] Format:
1167 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1168
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 oprofile.timer= [HW]
1170 Use timer interrupt instead of performance counters
1171
1172 optcd= [HW,CD]
1173 Format: <io>
1174
1175 osst= [HW,SCSI] SCSI Tape Driver
1176 Format: <buffer_size>,<write_threshold>
1177 See also Documentation/scsi/st.txt.
1178
1179 panic= [KNL] Kernel behaviour on panic
1180 Format: <timeout>
1181
1182 parkbd.port= [HW] Parallel port number the keyboard adapter is
1183 connected to, default is 0.
1184 Format: <parport#>
1185 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1186 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001187 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188
Randy Dunlapa9913042005-10-23 12:57:11 -07001189 parport= [HW,PPT] Specify parallel ports. 0 disables.
1190 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1191 Use 'auto' to force the driver to use any
1192 IRQ/DMA settings detected (the default is to
1193 ignore detected IRQ/DMA settings because of
1194 possible conflicts). You can specify the base
1195 address, IRQ, and DMA settings; IRQ and DMA
1196 should be numbers, or 'auto' (for using detected
1197 settings on that particular port), or 'nofifo'
1198 (to avoid using a FIFO even if it is detected).
1199 Parallel ports are assigned in the order they
1200 are specified on the command line, starting
1201 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202
Randy Dunlapa9913042005-10-23 12:57:11 -07001203 parport_init_mode= [HW,PPT]
1204 Configure VIA parallel port to operate in
1205 a specific mode. This is necessary on Pegasos
1206 computer where firmware has no options for setting
1207 up parallel port mode and sets it to spp.
1208 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 Format: [spp|ps2|epp|ecp|ecpepp]
1210
Randy Dunlapa9913042005-10-23 12:57:11 -07001211 pas2= [HW,OSS] Format:
1212 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1213
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 pas16= [HW,SCSI]
1215 See header of drivers/scsi/pas16.c.
1216
Andrew Mortondd287792006-03-23 03:00:57 -08001217 pause_on_oops=
1218 Halt all CPUs after the first oops has been printed for
1219 the specified number of seconds. This is to be used if
1220 your oopses keep scrolling off the screen.
1221
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 pcbit= [HW,ISDN]
1223
1224 pcd. [PARIDE]
1225 See header of drivers/block/paride/pcd.c.
1226 See also Documentation/paride.txt.
1227
Randy Dunlapa9913042005-10-23 12:57:11 -07001228 pci=option[,option...] [PCI] various PCI subsystem options:
1229 off [IA-32] don't probe for the PCI bus
1230 bios [IA-32] force use of PCI BIOS, don't access
1231 the hardware directly. Use this if your machine
1232 has a non-standard PCI host bridge.
1233 nobios [IA-32] disallow use of PCI BIOS, only direct
1234 hardware access methods are allowed. Use this
1235 if you experience crashes upon bootup and you
1236 suspect they are caused by the BIOS.
1237 conf1 [IA-32] Force use of PCI Configuration
1238 Mechanism 1.
1239 conf2 [IA-32] Force use of PCI Configuration
1240 Mechanism 2.
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001241 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1242 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001243 nomsi [MSI] If the PCI_MSI kernel config parameter is
1244 enabled, this kernel boot option can be used to
1245 disable the use of MSI interrupts system-wide.
Randy Dunlapa9913042005-10-23 12:57:11 -07001246 nosort [IA-32] Don't sort PCI devices according to
1247 order given by the PCI BIOS. This sorting is
1248 done to get a device order compatible with
1249 older kernels.
1250 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1251 routing table. These calls are known to be buggy
1252 on several machines and they hang the machine
1253 when used, but on other computers it's the only
1254 way to get the interrupt routing table. Try
1255 this option if the kernel is unable to allocate
1256 IRQs or discover secondary PCI buses on your
1257 motherboard.
1258 rom [IA-32] Assign address space to expansion ROMs.
1259 Use with caution as certain devices share
1260 address decoders between ROMs and other
1261 resources.
1262 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1263 assigned automatically to PCI devices. You can
1264 make the kernel exclude IRQs of your ISA cards
1265 this way.
jayalk@intworks.biz120bb422005-03-21 20:20:42 -08001266 pirqaddr=0xAAAAA [IA-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001267 of the PIRQ table (normally generated
1268 by the BIOS) if it is outside the
1269 F0000h-100000h range.
1270 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1271 useful if the kernel is unable to find your
1272 secondary buses and you want to tell it
1273 explicitly which ones they are.
1274 assign-busses [IA-32] Always assign all PCI bus
1275 numbers ourselves, overriding
1276 whatever the firmware may have done.
1277 usepirqmask [IA-32] Honor the possible IRQ mask stored
1278 in the BIOS $PIR table. This is needed on
1279 some systems with broken BIOSes, notably
1280 some HP Pavilion N5400 and Omnibook XE3
1281 notebooks. This will have no effect if ACPI
1282 IRQ routing is enabled.
1283 noacpi [IA-32] Do not use ACPI for IRQ routing
1284 or for PCI scanning.
1285 routeirq Do IRQ routing for all PCI devices.
1286 This is normally done in pci_enable_device(),
1287 so this option is a temporary workaround
1288 for broken drivers that don't call it.
1289 firmware [ARM] Do not re-enumerate the bus but instead
1290 just use the configuration from the
1291 bootloader. This is currently used on
1292 IXP2000 systems where the bus has to be
1293 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001294 noearly [X86] Don't do any early type 1 scanning.
1295 This might help on some broken boards which
1296 machine check when some devices' config space
1297 is read. But various workarounds are disabled
1298 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001299 bfsort Sort PCI devices into breadth-first order.
1300 This sorting is done to get a device
1301 order compatible with older (<= 2.4) kernels.
1302 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001303 cbiosize=nn[KMG] The fixed amount of bus space which is
1304 reserved for the CardBus bridge's IO window.
1305 The default value is 256 bytes.
1306 cbmemsize=nn[KMG] The fixed amount of bus space which is
1307 reserved for the CardBus bridge's memory
1308 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001309
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 pcmv= [HW,PCMCIA] BadgePAD 4
1311
1312 pd. [PARIDE]
1313 See Documentation/paride.txt.
1314
1315 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1316 boot time.
1317 Format: { 0 | 1 }
1318 See arch/parisc/kernel/pdc_chassis.c
1319
1320 pf. [PARIDE]
1321 See Documentation/paride.txt.
1322
1323 pg. [PARIDE]
1324 See Documentation/paride.txt.
1325
1326 pirq= [SMP,APIC] Manual mp-table setup
1327 See Documentation/i386/IO-APIC.txt.
1328
1329 plip= [PPT,NET] Parallel port network link
1330 Format: { parport<nr> | timid | 0 }
1331 See also Documentation/parport.txt.
1332
1333 pnpacpi= [ACPI]
1334 { off }
1335
1336 pnpbios= [ISAPNP]
1337 { on | off | curr | res | no-curr | no-res }
1338
1339 pnp_reserve_irq=
1340 [ISAPNP] Exclude IRQs for the autoconfiguration
1341
1342 pnp_reserve_dma=
1343 [ISAPNP] Exclude DMAs for the autoconfiguration
1344
1345 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001346 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347
1348 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001349 [ISAPNP] Exclude memory regions for the
1350 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 Ranges are in pairs (memory base and size).
1352
1353 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001354 Format: [schedule,]<number>
1355 Param: "schedule" - profile schedule points.
1356 Param: <number> - step/bucket size as a power of 2 for
1357 statistical time based profiling.
Ingo Molnarece8a682006-12-06 20:37:24 -08001358 Param: "sleep" - profile D-state sleeping (millisecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359
Randy Dunlapa9913042005-10-23 12:57:11 -07001360 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 Limit processor to maximum C-state
1362 max_cstate=9 overrides any DMI blacklist limit.
1363
Len Brown41c0d862005-12-28 12:43:51 -05001364 processor.nocst [HW,ACPI]
1365 Ignore the _CST method to determine C-states,
1366 instead using the legacy FADT method
1367
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1369 before loading.
1370 See Documentation/ramdisk.txt.
1371
Randy Dunlapa9913042005-10-23 12:57:11 -07001372 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1373 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1375 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001376 psmouse.resetafter= [HW,MOUSE]
1377 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 (0 = never).
1379 psmouse.resolution=
1380 [HW,MOUSE] Set desired mouse resolution, in dpi.
1381 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001382 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 0 = disabled, 1 = enabled (default).
1384
1385 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001386 Format:
1387 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388
1389 pt. [PARIDE]
1390 See Documentation/paride.txt.
1391
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001392 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001393
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 r128= [HW,DRM]
1395
1396 raid= [HW,RAID]
1397 See Documentation/md.txt.
1398
1399 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1400 See Documentation/ramdisk.txt.
1401
Randy Dunlapa9913042005-10-23 12:57:11 -07001402 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001404
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1406 New name for the ramdisk parameter.
1407 See Documentation/ramdisk.txt.
1408
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001409 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1410 RCU callbacks to process in one batch.
1411
1412 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1413 RCU callbacks over which batch limiting is disabled.
1414
1415 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1416 RCU callbacks below which batch limiting is re-enabled.
1417
Olof Johanssonffdfc402005-09-06 15:17:19 -07001418 rdinit= [KNL]
1419 Format: <full_path>
1420 Run specified binary instead of /init from the ramdisk,
1421 used for early userspace startup. See initrd.
1422
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1424 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Michael Opdenackerf3e299f2006-10-03 23:19:24 +02001425 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
1427 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1428
Zachary Amsden461a9af2006-09-25 23:32:25 -07001429 reservetop= [IA-32]
1430 Format: nn[KMG]
1431 Reserves a hole at the top of the kernel virtual
1432 address space.
1433
Vivek Goyal7e962872006-09-27 01:50:44 -07001434 reset_devices [KNL] Force drivers to reset the underlying device
1435 during initialization.
1436
Randy Dunlapa9913042005-10-23 12:57:11 -07001437 resume= [SWSUSP]
1438 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001440 resume_offset= [SWSUSP]
1441 Specify the offset from the beginning of the partition
1442 given by "resume=" at which the swap header is located,
1443 in <PAGE_SIZE> units (needed only for swap files).
1444 See Documentation/power/swsusp-and-swap-files.txt
1445
Michael Neuling0a7b35c2007-02-10 01:44:33 -08001446 retain_initrd [RAM] Keep initrd memory after extraction
1447
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 rhash_entries= [KNL,NET]
1449 Set number of hash buckets for route cache
1450
1451 riscom8= [HW,SERIAL]
1452 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1453
1454 ro [KNL] Mount root device read-only on boot
1455
1456 root= [KNL] Root filesystem
1457
1458 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1459 mount the root filesystem
1460
1461 rootflags= [KNL] Set root filesystem mount option string
1462
1463 rootfstype= [KNL] Set root filesystem type
1464
1465 rw [KNL] Mount root device read-write on boot
1466
1467 S [KNL] Run init in single mode
1468
1469 sa1100ir [NET]
1470 See drivers/net/irda/sa1100_ir.c.
1471
1472 sb= [HW,OSS]
1473 Format: <io>,<irq>,<dma>,<dma2>
1474
1475 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001476
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 sbpcd= [HW,CD] Soundblaster CD adapter
1478 Format: <io>,<type>
1479 See a comment before function sbpcd_setup() in
1480 drivers/cdrom/sbpcd.c.
1481
1482 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1483 Format: <io>[,<timeout>[,<isapnp>]]
1484
1485 scsi_debug_*= [SCSI]
1486 See drivers/scsi/scsi_debug.c.
1487
1488 scsi_default_dev_flags=
1489 [SCSI] SCSI default device flags
1490 Format: <integer>
1491
1492 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1493 Format: <vendor>:<model>:<flags>
1494 (flags are integer value)
1495
1496 scsi_logging= [SCSI]
1497
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001498 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1499 discovered. async scans them in kernel threads,
1500 allowing boot to proceed. none ignores them, expecting
1501 user space to do the scan.
1502
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 selinux [SELINUX] Disable or enable SELinux at boot time.
1504 Format: { "0" | "1" }
1505 See security/selinux/Kconfig help text.
1506 0 -- disable.
1507 1 -- enable.
1508 Default value is set via kernel config option.
1509 If enabled at boot time, /selinux/disable can be used
1510 later to disable prior to initial policy load.
1511
James Morris4e5ab4c2006-06-09 00:33:33 -07001512 selinux_compat_net =
1513 [SELINUX] Set initial selinux_compat_net flag value.
1514 Format: { "0" | "1" }
1515 0 -- use new secmark-based packet controls
1516 1 -- use legacy packet controls
1517 Default value is 0 (preferred).
1518 Value can be changed at runtime via
1519 /selinux/compat_net.
1520
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521 serialnumber [BUGS=IA-32]
1522
Randy Dunlapa9913042005-10-23 12:57:11 -07001523 sg_def_reserved_size= [SCSI]
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 shapers= [NET]
1526 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001527
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528 sim710= [SCSI,HW]
1529 See header of drivers/scsi/sim710.c.
1530
1531 simeth= [IA-64]
1532 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001533
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 sjcd= [HW,CD]
1535 Format: <io>,<irq>,<dma>
1536 See header of drivers/cdrom/sjcd.c.
1537
1538 slram= [HW,MTD]
1539
1540 smart2= [HW]
1541 Format: <io1>[,<io2>[,...,<io8>]]
1542
1543 snd-ad1816a= [HW,ALSA]
1544
1545 snd-ad1848= [HW,ALSA]
1546
1547 snd-ali5451= [HW,ALSA]
1548
1549 snd-als100= [HW,ALSA]
1550
1551 snd-als4000= [HW,ALSA]
1552
1553 snd-azt2320= [HW,ALSA]
1554
1555 snd-cmi8330= [HW,ALSA]
1556
1557 snd-cmipci= [HW,ALSA]
1558
1559 snd-cs4231= [HW,ALSA]
1560
1561 snd-cs4232= [HW,ALSA]
1562
1563 snd-cs4236= [HW,ALSA]
1564
1565 snd-cs4281= [HW,ALSA]
1566
1567 snd-cs46xx= [HW,ALSA]
1568
1569 snd-dt019x= [HW,ALSA]
1570
1571 snd-dummy= [HW,ALSA]
1572
1573 snd-emu10k1= [HW,ALSA]
1574
1575 snd-ens1370= [HW,ALSA]
1576
1577 snd-ens1371= [HW,ALSA]
1578
1579 snd-es968= [HW,ALSA]
1580
1581 snd-es1688= [HW,ALSA]
1582
1583 snd-es18xx= [HW,ALSA]
1584
1585 snd-es1938= [HW,ALSA]
1586
1587 snd-es1968= [HW,ALSA]
1588
1589 snd-fm801= [HW,ALSA]
1590
1591 snd-gusclassic= [HW,ALSA]
1592
1593 snd-gusextreme= [HW,ALSA]
1594
1595 snd-gusmax= [HW,ALSA]
1596
1597 snd-hdsp= [HW,ALSA]
1598
1599 snd-ice1712= [HW,ALSA]
1600
1601 snd-intel8x0= [HW,ALSA]
1602
1603 snd-interwave= [HW,ALSA]
1604
1605 snd-interwave-stb=
1606 [HW,ALSA]
1607
1608 snd-korg1212= [HW,ALSA]
1609
1610 snd-maestro3= [HW,ALSA]
1611
1612 snd-mpu401= [HW,ALSA]
1613
1614 snd-mtpav= [HW,ALSA]
1615
1616 snd-nm256= [HW,ALSA]
1617
1618 snd-opl3sa2= [HW,ALSA]
1619
1620 snd-opti92x-ad1848=
1621 [HW,ALSA]
1622
1623 snd-opti92x-cs4231=
1624 [HW,ALSA]
1625
1626 snd-opti93x= [HW,ALSA]
1627
1628 snd-pmac= [HW,ALSA]
1629
1630 snd-rme32= [HW,ALSA]
1631
1632 snd-rme96= [HW,ALSA]
1633
1634 snd-rme9652= [HW,ALSA]
1635
1636 snd-sb8= [HW,ALSA]
1637
1638 snd-sb16= [HW,ALSA]
1639
1640 snd-sbawe= [HW,ALSA]
1641
1642 snd-serial= [HW,ALSA]
1643
1644 snd-sgalaxy= [HW,ALSA]
1645
1646 snd-sonicvibes= [HW,ALSA]
1647
1648 snd-sun-amd7930=
1649 [HW,ALSA]
1650
1651 snd-sun-cs4231= [HW,ALSA]
1652
1653 snd-trident= [HW,ALSA]
1654
1655 snd-usb-audio= [HW,ALSA,USB]
1656
1657 snd-via82xx= [HW,ALSA]
1658
1659 snd-virmidi= [HW,ALSA]
1660
1661 snd-wavefront= [HW,ALSA]
1662
1663 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001664
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 sonycd535= [HW,CD]
1666 Format: <io>[,<irq>]
1667
1668 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1669 See Documentation/sonypi.txt
1670
1671 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1672 See Documentation/specialix.txt.
1673
1674 spia_io_base= [HW,MTD]
1675 spia_fio_base=
1676 spia_pedr=
1677 spia_peddr=
1678
1679 sscape= [HW,OSS]
1680 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07001681
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1683 See Documentation/scsi/st.txt.
1684
1685 st0x= [HW,SCSI]
1686 See header of drivers/scsi/seagate.c.
1687
1688 sti= [PARISC,HW]
1689 Format: <num>
1690 Set the STI (builtin display/keyboard on the HP-PARISC
1691 machines) console (graphic card) which should be used
1692 as the initial boot-console.
1693 See also comment in drivers/video/console/sticore.c.
1694
1695 sti_font= [HW]
1696 See comment in drivers/video/console/sticore.c.
1697
1698 stifb= [HW]
1699 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1700
Greg Banks42a7fc42007-03-06 01:42:23 -08001701 sunrpc.pool_mode=
1702 [NFS]
1703 Control how the NFS server code allocates CPUs to
1704 service thread pools. Depending on how many NICs
1705 you have and where their interrupts are bound, this
1706 option will affect which CPUs will do NFS serving.
1707 Note: this parameter cannot be changed while the
1708 NFS server is running.
1709
1710 auto the server chooses an appropriate mode
1711 automatically using heuristics
1712 global a single global pool contains all CPUs
1713 percpu one pool for each CPU
1714 pernode one pool for each NUMA node (equivalent
1715 to global on non-NUMA machines)
1716
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07001718
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 switches= [HW,M68k]
1720
1721 sym53c416= [HW,SCSI]
1722 See header of drivers/scsi/sym53c416.c.
1723
Ingo Molnar5d6f6472006-12-13 00:34:36 -08001724 sysrq_always_enabled
1725 [KNL]
1726 Ignore sysrq setting - this boot parameter will
1727 neutralize any effect of /proc/sys/kernel/sysrq.
1728 Useful for debugging.
1729
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 t128= [HW,SCSI]
1731 See header of drivers/scsi/t128.c.
1732
1733 tdfx= [HW,DRM]
1734
1735 thash_entries= [KNL,NET]
1736 Set number of hash buckets for TCP connection
1737
1738 time Show timing data prefixed to each printk message line
1739
john stultz734efb42006-06-26 00:25:05 -07001740 clocksource= [GENERIC_TIME] Override the default clocksource
1741 Override the default clocksource and use the clocksource
1742 with the name specified.
1743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 tipar.timeout= [HW,PPT]
1745 Set communications timeout in tenths of a second
1746 (default 15).
1747
1748 tipar.delay= [HW,PPT]
1749 Set inter-bit delay in microseconds (default 10).
1750
1751 tmc8xx= [HW,SCSI]
1752 See header of drivers/scsi/seagate.c.
1753
1754 tmscsim= [HW,SCSI]
1755 See comment before function dc390_setup() in
1756 drivers/scsi/tmscsim.c.
1757
1758 tp720= [HW,PS2]
1759
1760 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07001761 Format:
1762 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1763
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 tsdev.xres= [TS] Horizontal screen resolution.
1765 tsdev.yres= [TS] Vertical screen resolution.
1766
Randy Dunlapa9913042005-10-23 12:57:11 -07001767 turbografx.map[2|3]= [HW,JOY]
1768 TurboGraFX parallel port interface
1769 Format:
1770 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 See also Documentation/input/joystick-parport.txt
1772
1773 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1774 See header of drivers/scsi/u14-34f.c.
1775
1776 uart401= [HW,OSS]
1777 Format: <io>,<irq>
1778
1779 uart6850= [HW,OSS]
1780 Format: <io>,<irq>
1781
Alan Stern5f8364b2006-12-05 16:29:55 -05001782 uhci-hcd.ignore_oc=
1783 [USB] Ignore overcurrent events (default N).
1784 Some badly-designed motherboards generate lots of
1785 bogus events, for ports that aren't wired to
1786 anything. Set this parameter to avoid log spamming.
1787 Note that genuine overcurrent events won't be
1788 reported either.
1789
Alan Sternb5e795f2007-02-20 15:00:53 -05001790 usbcore.autosuspend=
1791 [USB] The autosuspend time delay (in seconds) used
1792 for newly-detected USB devices (default 2). This
1793 is the time required before an idle device will be
1794 autosuspended. Devices for which the delay is set
1795 to 0 won't be autosuspended at all.
1796
Linus Torvalds1da177e2005-04-16 15:20:36 -07001797 usbhid.mousepoll=
1798 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07001799
Paul Mundte523d932007-02-28 18:30:01 +09001800 vdso= [IA-32,SH]
Ingo Molnare6e54942006-06-27 02:53:50 -07001801 vdso=1: enable VDSO (default)
1802 vdso=0: disable VDSO mapping
1803
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 video= [FB] Frame buffer configuration
1805 See Documentation/fb/modedb.txt.
1806
1807 vga= [BOOT,IA-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07001808 See Documentation/i386/boot.txt and
1809 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 Use vga=ask for menu.
1811 This is actually a boot loader parameter; the value is
1812 passed to the kernel using a special protocol.
1813
Randy Dunlapa9913042005-10-23 12:57:11 -07001814 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 size of <nn>. This can be used to increase the
1816 minimum size (128MB on x86). It can also be used to
1817 decrease the size and leave more room for directly
1818 mapped kernel RAM.
1819
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001820 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1821 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822
Peter Oberparleiter585c3042006-06-29 15:08:25 +02001823 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1824 Format: <command>
1825
1826 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1827 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07001828
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829 waveartist= [HW,OSS]
1830 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07001831
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 wd33c93= [HW,SCSI]
1833 See header of drivers/scsi/wd33c93.c.
1834
1835 wd7000= [HW,SCSI]
1836 See header of drivers/scsi/wd7000.c.
1837
1838 wdt= [WDT] Watchdog
1839 See Documentation/watchdog/watchdog.txt.
1840
1841 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1842 xd_geo= See header of drivers/block/xd.c.
1843
1844 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07001845 Format:
1846 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847
Andi Kleena62eaf12006-02-16 23:41:58 +01001848 norandmaps Don't use address space randomization
1849 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1850
Jan Beulich6d0185e2006-12-07 02:14:13 +01001851 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1852 This is useful to get more information why
1853 you got a "dwarf2 unwinder stuck"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854
Randy Dunlapa9913042005-10-23 12:57:11 -07001855______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856
1857TODO:
1858
1859 Add documentation for ALSA options.
1860 Add more DRM drivers.