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0ee9d71f 1 Kernel Parameters
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2 ~~~~~~~~~~~~~~~~~
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
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20This 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
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27The 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:
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31
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.
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38 DEVFS devfs support is enabled.
39 DRM Direct Rendering Management support is enabled.
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40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
45 IA-32 IA-32 aka i386 architecture is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 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.
309e57df 60 MSI Message Signaled Interrupts (PCI).
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61 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
734efb46 64 GENERIC_TIME The generic timeofday code is enabled.
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65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PARIDE The ParIDE subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
79 Documentation/scsi/.
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
82 SMP The kernel is an SMP kernel.
83 SPARC Sparc architecture is enabled.
a9913044 84 SWSUSP Software suspend is enabled.
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85 TS Appropriate touchscreen support is enabled.
86 USB USB support is enabled.
87 USBHID USB Human Interface Device support is enabled.
88 V4L Video For Linux support is enabled.
89 VGA The VGA console has been enabled.
90 VT Virtual terminal support is enabled.
91 WDT Watchdog support is enabled.
92 XT IBM PC/XT MFM hard disk support is enabled.
93 X86-64 X86-64 architecture is enabled.
94 More X86-64 boot options can be found in
95 Documentation/x86_64/boot-options.txt .
96
97In addition, the following text indicates that the option:
98
99 BUGS= Relates to possible processor bugs on the said processor.
100 KNL Is a kernel start-up parameter.
101 BOOT Is a boot loader parameter.
102
103Parameters denoted with BOOT are actually interpreted by the boot
104loader, and have no meaning to the kernel directly.
105Do not modify the syntax of boot loader parameters without extreme
106need or coordination with <Documentation/i386/boot.txt>.
107
108Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
109a trailing = on the name of any parameter states that that parameter will
110be entered as an environment variable, whereas its absence indicates that
111it will appear as a kernel argument readable via /proc/cmdline by programs
112running once the system is up.
113
114 53c7xx= [HW,SCSI] Amiga SCSI controllers
115 See header of drivers/scsi/53c7xx.c.
116 See also Documentation/scsi/ncr53c7xx.txt.
117
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118 acpi= [HW,ACPI] Advanced Configuration and Power Interface
119 Format: { force | off | ht | strict | noirq }
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120 force -- enable ACPI if default was off
121 off -- disable ACPI if default was on
122 noirq -- do not use ACPI for IRQ routing
123 ht -- run only enough ACPI to enable Hyper Threading
a9913044 124 strict -- Be less tolerant of platforms that are not
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125 strictly ACPI specification compliant.
126
127 See also Documentation/pm.txt, pci=noacpi
128
129 acpi_sleep= [HW,ACPI] Sleep options
130 Format: { s3_bios, s3_mode }
131 See Documentation/power/video.txt
a9913044 132
1da177e4 133 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 134 Format: { level | edge | high | low }
1da177e4 135
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136 acpi_irq_balance [HW,ACPI]
137 ACPI will balance active IRQs
138 default in APIC mode
1da177e4 139
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140 acpi_irq_nobalance [HW,ACPI]
141 ACPI will not move active IRQs (default)
142 default in PIC mode
1da177e4 143
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144 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
145 use by PCI
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146 Format: <irq>,<irq>...
147
a9913044 148 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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149 Format: <irq>,<irq>...
150
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151 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
152 Format: To spoof as Windows 98: ="Microsoft Windows"
153
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154 acpi_osi= [HW,ACPI] empty param disables _OSI
155
156 acpi_serialize [HW,ACPI] force serialization of AML methods
157
158 acpi_skip_timer_override [HW,ACPI]
159 Recognize and ignore IRQ0/pin2 Interrupt Override.
160 For broken nForce2 BIOS resulting in XT-PIC timer.
161
162 acpi_dbg_layer= [HW,ACPI]
163 Format: <int>
a9913044 164 Each bit of the <int> indicates an ACPI debug layer,
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165 1: enable, 0: disable. It is useful for boot time
166 debugging. After system has booted up, it can be set
167 via /proc/acpi/debug_layer.
168
169 acpi_dbg_level= [HW,ACPI]
170 Format: <int>
a9913044 171 Each bit of the <int> indicates an ACPI debug level,
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172 1: enable, 0: disable. It is useful for boot time
173 debugging. After system has booted up, it can be set
174 via /proc/acpi/debug_level.
175
176 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
177
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178 acpi_generic_hotkey [HW,ACPI]
179 Allow consolidated generic hotkey driver to
a9913044 180 override platform specific driver.
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181 See also Documentation/acpi-hotkey.txt.
182
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183 acpi_pm_good [IA-32,X86-64]
184 Override the pmtimer bug detection: force the kernel
185 to assume that this machine's pmtimer latches its value
186 and always returns good values.
187
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188 enable_timer_pin_1 [i386,x86-64]
189 Enable PIN 1 of APIC timer
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190 Can be useful to work around chipset bugs
191 (in particular on some ATI chipsets).
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192 The kernel tries to set a reasonable default.
193
194 disable_timer_pin_1 [i386,x86-64]
195 Disable PIN 1 of APIC timer
196 Can be useful to work around chipset bugs.
197
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198 ad1816= [HW,OSS]
199 Format: <io>,<irq>,<dma>,<dma2>
200 See also Documentation/sound/oss/AD1816.
201
202 ad1848= [HW,OSS]
203 Format: <io>,<irq>,<dma>,<dma2>,<type>
204
205 adlib= [HW,OSS]
206 Format: <io>
a9913044 207
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208 advansys= [HW,SCSI]
209 See header of drivers/scsi/advansys.c.
210
211 advwdt= [HW,WDT] Advantech WDT
212 Format: <iostart>,<iostop>
213
214 aedsp16= [HW,OSS] Audio Excel DSP 16
215 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
216 See also header of sound/oss/aedsp16.c.
a9913044 217
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218 aha152x= [HW,SCSI]
219 See Documentation/scsi/aha152x.txt.
220
221 aha1542= [HW,SCSI]
222 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
223
224 aic7xxx= [HW,SCSI]
225 See Documentation/scsi/aic7xxx.txt.
226
227 aic79xx= [HW,SCSI]
228 See Documentation/scsi/aic79xx.txt.
229
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230 amijoy.map= [HW,JOY] Amiga joystick support
231 Map of devices attached to JOY0DAT and JOY1DAT
232 Format: <a>,<b>
233 See also Documentation/kernel/input/joystick.txt
234
235 analog.map= [HW,JOY] Analog joystick and gamepad support
236 Specifies type or capabilities of an analog joystick
237 connected to one of 16 gameports
238 Format: <type1>,<type2>,..<type16>
239
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240 apc= [HW,SPARC]
241 Power management functions (SPARCstation-4/5 + deriv.)
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242 Format: noidle
243 Disable APC CPU standby support. SPARCstation-Fox does
244 not play well with APC CPU idle - disable it if you have
245 APC and your system crashes randomly.
246
a9913044 247 apic= [APIC,i386] Change the output verbosity whilst booting
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248 Format: { quiet (default) | verbose | debug }
249 Change the amount of debugging information output
250 when initialising the APIC and IO-APIC components.
a9913044 251
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252 apm= [APM] Advanced Power Management
253 See header of arch/i386/kernel/apm.c.
254
255 applicom= [HW]
256 Format: <mem>,<irq>
a9913044 257
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258 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
259 Format: <io>,<irq>,<nodeID>
260
261 ataflop= [HW,M68k]
262
263 atarimouse= [HW,MOUSE] Atari Mouse
264
265 atascsi= [HW,SCSI] Atari SCSI
266
267 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
268 EzKey and similar keyboards
269
270 atkbd.reset= [HW] Reset keyboard during initialization
271
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272 atkbd.set= [HW] Select keyboard code set
273 Format: <int> (2 = AT (default), 3 = PS/2)
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274
275 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
276 keyboards
277
278 atkbd.softraw= [HW] Choose between synthetic and real raw mode
279 Format: <bool> (0 = real, 1 = synthetic (default))
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280
281 atkbd.softrepeat= [HW]
282 Use software keyboard repeat
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283
284 autotest [IA64]
285
286 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
287 Format: <io>,<memsize>,<isapnp>
a9913044 288
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289 aztcd= [HW,CD] Aztech CD268 CDROM driver
290 Format: <io>,0x79 (?)
291
292 baycom_epp= [HW,AX25]
293 Format: <io>,<mode>
a9913044 294
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295 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
296 Format: <io>,<mode>
297 See header of drivers/net/hamradio/baycom_par.c.
298
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299 baycom_ser_fdx= [HW,AX25]
300 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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301 Format: <io>,<irq>,<mode>[,<baud>]
302 See header of drivers/net/hamradio/baycom_ser_fdx.c.
303
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304 baycom_ser_hdx= [HW,AX25]
305 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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306 Format: <io>,<irq>,<mode>
307 See header of drivers/net/hamradio/baycom_ser_hdx.c.
308
309 blkmtd_device= [HW,MTD]
310 blkmtd_erasesz=
311 blkmtd_ro=
312 blkmtd_bs=
313 blkmtd_count=
314
315 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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316 bttv.radio= Most important insmod options are available as
317 kernel args too.
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318 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
319 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
320
321 BusLogic= [HW,SCSI]
322 See drivers/scsi/BusLogic.c, comment before function
323 BusLogic_ParseDriverOptions().
324
325 c101= [NET] Moxa C101 synchronous serial card
326
327 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
328 Sometimes CPU hardware bugs make them report the cache
329 size incorrectly. The kernel will attempt work arounds
330 to fix known problems, but for some CPUs it is not
331 possible to determine what the correct size should be.
332 This option provides an override for these situations.
333
334 cdu31a= [HW,CD]
335 Format: <io>,<irq>[,PAS]
336 See header of drivers/cdrom/cdu31a.c.
337
338 chandev= [HW,NET] Generic channel device initialisation
339
340 checkreqprot [SELINUX] Set initial checkreqprot flag value.
341 Format: { "0" | "1" }
342 See security/selinux/Kconfig help text.
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343 0 -- check protection applied by kernel (includes
344 any implied execute protection).
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345 1 -- check protection requested by application.
346 Default value is set via a kernel config option.
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347 Value can be changed at runtime via
348 /selinux/checkreqprot.
349
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350 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
351 [Deprecated]
352 Forces specified clocksource (if avaliable) to be used
353 when calculating gettimeofday(). If specified
354 clocksource is not avalible, it defaults to PIT.
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355 Format: { pit | tsc | cyclone | pmtmr }
356
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357 disable_8254_timer
358 enable_8254_timer
359 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
360 over the 8254 in addition to over the IO-APIC. The
361 kernel tries to set a sensible default.
362
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363 hpet= [IA-32,HPET] option to disable HPET and use PIT.
364 Format: disable
365
366 cm206= [HW,CD]
367 Format: { auto | [<io>,][<irq>] }
368
369 com20020= [HW,NET] ARCnet - COM20020 chipset
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370 Format:
371 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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372
373 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
374 Format: <io>[,<irq>]
375
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376 com90xx= [HW,NET]
377 ARCnet - COM90xx chipset (memory-mapped buffers)
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378 Format: <io>[,<irq>[,<memstart>]]
379
380 condev= [HW,S390] console device
381 conmode=
a9913044 382
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383 console= [KNL] Output console device and options.
384
385 tty<n> Use the virtual console device <n>.
386
387 ttyS<n>[,options]
f1a1c2dc 388 ttyUSB0[,options]
1da177e4 389 Use the specified serial port. The options are of
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390 the form "bbbbpnf", where "bbbb" is the baud rate,
391 "p" is parity ("n", "o", or "e"), "n" is number of
392 bits, and "f" is flow control ("r" for RTS or
393 omit it). Default is "9600n8".
394
395 See Documentation/serial-console.txt for more
396 information. See
397 Documentation/networking/netconsole.txt for an
398 alternative.
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399
400 uart,io,<addr>[,options]
401 uart,mmio,<addr>[,options]
402 Start an early, polled-mode console on the 8250/16550
403 UART at the specified I/O port or MMIO address,
404 switching to the matching ttyS device later. The
405 options are the same as for ttyS, above.
406
407 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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408 Format:
409 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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410
411 cpia_pp= [HW,PPT]
412 Format: { parport<nr> | auto | none }
413
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414 crashkernel=nn[KMG]@ss[KMG]
415 [KNL] Reserve a chunk of physical memory to
416 hold a kernel to switch to with kexec on panic.
417
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418 cs4232= [HW,OSS]
419 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
420
421 cs89x0_dma= [HW,NET]
422 Format: <dma>
423
424 cs89x0_media= [HW,NET]
425 Format: { rj45 | aui | bnc }
a9913044 426
1da177e4 427 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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428
429 dasd= [HW,NET]
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430 See header of drivers/s390/block/dasd_devmap.c.
431
432 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
433 (one device per port)
434 Format: <port#>,<type>
435 See also Documentation/input/joystick-parport.txt
436
437 debug [KNL] Enable kernel debugging (events log level).
438
439 decnet= [HW,NET]
440 Format: <area>[,<node>]
441 See also Documentation/networking/decnet.txt.
442
443 devfs= [DEVFS]
444 See Documentation/filesystems/devfs/boot-options.
445
446 dhash_entries= [KNL]
447 Set number of hash buckets for dentry cache.
a9913044 448
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449 digi= [HW,SERIAL]
450 IO parameters + enable/disable command.
451
452 digiepca= [HW,SERIAL]
453 See drivers/char/README.epca and
454 Documentation/digiepca.txt.
455
456 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
457 support available.
458 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
459
460 dmasound= [HW,OSS] Sound subsystem buffers
461
462 dscc4.setup= [NET]
463
464 dtc3181e= [HW,SCSI]
465
a9913044 466 earlyprintk= [IA-32,X86-64]
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467 earlyprintk=vga
468 earlyprintk=serial[,ttySn[,baudrate]]
469
a9913044 470 Append ",keep" to not disable it when the real console
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471 takes over.
472
473 Only vga or serial at a time, not both.
474
475 Currently only ttyS0 and ttyS1 are supported.
476
477 Interaction with the standard serial driver is not
478 very good.
479
480 The VGA output is eventually overwritten by the real
481 console.
482
483 eata= [HW,SCSI]
484
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485 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
486 Format: <int>
487 0: polling mode
488 non-0: interrupt mode (default)
489
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490 eda= [HW,PS2]
491
492 edb= [HW,PS2]
493
494 edd= [EDD]
495 Format: {"of[f]" | "sk[ipmbr]"}
496 See comment in arch/i386/boot/edd.S
497
a9913044 498 eicon= [HW,ISDN]
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499 Format: <id>,<membase>,<irq>
500
501 eisa_irq_edge= [PARISC,HW]
502 See header of drivers/parisc/eisa.c.
503
504 elanfreq= [IA-32]
505 See comment before function elanfreq_setup() in
506 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
507
508 elevator= [IOSCHED]
16ab3adf 509 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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510 See Documentation/block/as-iosched.txt and
511 Documentation/block/deadline-iosched.txt for details.
512
aac04b32 513 elfcorehdr= [IA-32, X86_64]
a9913044 514 Specifies physical address of start of kernel core
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515 image elf header. Generally kexec loader will
516 pass this option to capture kernel.
517 See Documentation/kdump/kdump.txt for details.
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518
519 enforcing [SELINUX] Set initial enforcing status.
520 Format: {"0" | "1"}
521 See security/selinux/Kconfig help text.
522 0 -- permissive (log only, no denials).
523 1 -- enforcing (deny and log).
524 Default value is 0.
525 Value can be changed at runtime via /selinux/enforce.
526
527 es1370= [HW,OSS]
528 Format: <lineout>[,<micbias>]
529 See also header of sound/oss/es1370.c.
530
531 es1371= [HW,OSS]
532 Format: <spdif>,[<nomix>,[<amplifier>]]
533 See also header of sound/oss/es1371.c.
a9913044 534
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535 ether= [HW,NET] Ethernet cards parameters
536 This option is obsoleted by the "netdev=" option, which
537 has equivalent usage. See its documentation for details.
538
539 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
540 Format: <io>[,<irq>]
541
542 fd_mcs= [HW,SCSI]
543 See header of drivers/scsi/fd_mcs.c.
544
545 fdomain= [HW,SCSI]
546 See header of drivers/scsi/fdomain.c.
547
548 floppy= [HW]
549 See Documentation/floppy.txt.
550
551 ftape= [HW] Floppy Tape subsystem debugging options.
552 See Documentation/ftape.txt.
553
554 gamecon.map[2|3]=
555 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
556 support via parallel port (up to 5 devices per port)
557 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
558 See also Documentation/input/joystick-parport.txt
559
560 gamma= [HW,DRM]
561
562 gdth= [HW,SCSI]
563 See header of drivers/scsi/gdth.c.
564
565 gpt [EFI] Forces disk with valid GPT signature but
566 invalid Protective MBR to be treated as GPT.
567
568 gscd= [HW,CD]
569 Format: <io>
570
571 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
572
573 gus= [HW,OSS]
574 Format: <io>,<irq>,<dma>,<dma16>
a9913044 575
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576 gvp11= [HW,SCSI]
577
578 hashdist= [KNL,NUMA] Large hashes allocated during boot
579 are distributed across NUMA nodes. Defaults on
580 for IA-64, off otherwise.
a9913044 581 Format: 0 | 1 (for off | on)
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582
583 hcl= [IA-64] SGI's Hardware Graph compatibility layer
584
585 hd= [EIDE] (E)IDE hard drive subsystem geometry
586 Format: <cyl>,<head>,<sect>
587
588 hd?= [HW] (E)IDE subsystem
589 hd?lun= See Documentation/ide.txt.
590
591 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
592 size of <nn>. This works even on boxes that have no
593 highmem otherwise. This also works to reduce highmem
594 size on bigger boxes.
595
596 hisax= [HW,ISDN]
597 See Documentation/isdn/README.HiSax.
598
599 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
600
601 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
602
603 i8042.direct [HW] Put keyboard port into non-translated mode
604 i8042.dumbkbd [HW] Pretend that controlled can only read data from
605 keyboard and can not control its state
606 (Don't attempt to blink the leds)
607 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 608 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
609 i8042.nomux [HW] Don't check presence of an active multiplexing
610 controller
611 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
612 controllers
613 i8042.panicblink=
614 [HW] Frequency with which keyboard LEDs should blink
615 when kernel panics (default is 0.5 sec)
616 i8042.reset [HW] Reset the controller during init and cleanup
617 i8042.unlock [HW] Unlock (ignore) the keylock
618
619 i810= [HW,DRM]
620
e70c9d5e
DT
621 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
622 indicates that the driver is running on unsupported
623 hardware.
1da177e4
LT
624 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
625 does not match list of supported models.
626 i8k.power_status
627 [HW] Report power status in /proc/i8k
628 (disabled by default)
629 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
630 capability is set.
631
632 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
633 See Documentation/mca.txt.
634
635 icn= [HW,ISDN]
636 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
637
638 ide= [HW] (E)IDE subsystem
639 Format: ide=nodma or ide=doubler or ide=reverse
640 See Documentation/ide.txt.
641
642 ide?= [HW] (E)IDE subsystem
643 Format: ide?=noprobe or chipset specific parameters.
644 See Documentation/ide.txt.
a9913044 645
1da177e4
LT
646 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
647 See Documentation/ide.txt.
648
649 idle= [HW]
650 Format: idle=poll or idle=halt
a9913044 651
1da177e4
LT
652 ihash_entries= [KNL]
653 Set number of hash buckets for inode cache.
654
655 in2000= [HW,SCSI]
656 See header of drivers/scsi/in2000.c.
657
658 init= [KNL]
659 Format: <full_path>
660 Run specified binary instead of /sbin/init as init
661 process.
662
663 initcall_debug [KNL] Trace initcalls as they are executed. Useful
664 for working out where the kernel is dying during
665 startup.
666
667 initrd= [BOOT] Specify the location of the initial ramdisk
668
669 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
670 Format: <irq>
671
2bd0fa3b
JB
672 combined_mode= [HW] control which driver uses IDE ports in combined
673 mode: legacy IDE driver, libata, or both
674 (in the libata case, libata.atapi_enabled=1 may be
675 useful as well). Note that using the ide or libata
676 options may affect your device naming (e.g. by
677 changing hdc to sdb).
678 Format: combined (default), ide, or libata
679
1da177e4
LT
680 inttest= [IA64]
681
682 io7= [HW] IO7 for Marvel based alpha systems
683 See comment before marvel_specify_io7 in
684 arch/alpha/kernel/core_marvel.c.
685
686 ip= [IP_PNP]
687 See Documentation/nfsroot.txt.
688
689 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
690 See comment before ip2_setup() in drivers/char/ip2.c.
691
692 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
693 See header of drivers/scsi/ips.c.
694
200803df
AC
695 irqfixup [HW]
696 When an interrupt is not handled search all handlers
697 for it. Intended to get systems with badly broken
698 firmware running.
699
700 irqpoll [HW]
701 When an interrupt is not handled search all handlers
702 for it. Also check all handlers each timer
703 interrupt. Intended to get systems with badly broken
704 firmware running.
705
1da177e4 706 isapnp= [ISAPNP]
a9913044 707 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
708
709 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
710 Format: <cpu number>,...,<cpu number>
711 This option can be used to specify one or more CPUs
712 to isolate from the general SMP balancing and scheduling
713 algorithms. The only way to move a process onto or off
714 an "isolated" CPU is via the CPU affinity syscalls.
715 <cpu number> begins at 0 and the maximum value is
716 "number of CPUs in system - 1".
717
718 This option is the preferred way to isolate CPUs. The
a9913044
RD
719 alternative -- manually setting the CPU mask of all
720 tasks in the system -- can cause problems and
721 suboptimal load balancer performance.
1da177e4
LT
722
723 isp16= [HW,CD]
724 Format: <io>,<irq>,<dma>,<setup>
725
a9913044 726 iucv= [HW,NET]
1da177e4
LT
727
728 js= [HW,JOY] Analog joystick
729 See Documentation/input/joystick.txt.
730
731 keepinitrd [HW,ARM]
732
a9913044 733 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
734 in oops dumps.
735
736 l2cr= [PPC]
737
a9913044
RD
738 lapic [IA-32,APIC] Enable the local APIC even if BIOS
739 disabled it.
1da177e4
LT
740
741 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
742 Format: addr:<io>,irq:<irq>
743
a9913044
RD
744 llsc*= [IA64] See function print_params() in
745 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
746
747 load_ramdisk= [RAM] List of ramdisks to load from floppy
748 See Documentation/ramdisk.txt.
749
a6b25b67
RD
750 lockd.nlm_grace_period=P [NFS] Assign grace period.
751 Format: <integer>
1da177e4 752
a6b25b67
RD
753 lockd.nlm_tcpport=N [NFS] Assign TCP port.
754 Format: <integer>
755
756 lockd.nlm_timeout=T [NFS] Assign timeout value.
757 Format: <integer>
758
759 lockd.nlm_udpport=M [NFS] Assign UDP port.
760 Format: <integer>
1da177e4
LT
761
762 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
763 Format: <irq>
764
765 loglevel= All Kernel Messages with a loglevel smaller than the
766 console loglevel will be printed to the console. It can
767 also be changed with klogd or other programs. The
768 loglevels are defined as follows:
769
770 0 (KERN_EMERG) system is unusable
771 1 (KERN_ALERT) action must be taken immediately
772 2 (KERN_CRIT) critical conditions
773 3 (KERN_ERR) error conditions
774 4 (KERN_WARNING) warning conditions
775 5 (KERN_NOTICE) normal but significant condition
776 6 (KERN_INFO) informational
777 7 (KERN_DEBUG) debug-level messages
778
779 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
780 Format: { n | nk | nM }
781 n must be a power of two. The default size
782 is set in the kernel config file.
1da177e4
LT
783
784 lp=0 [LP] Specify parallel ports to use, e.g,
785 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
786 lp=reset first parallel port). 'lp=0' disables the
787 lp=auto printer driver. 'lp=reset' (which can be
788 specified in addition to the ports) causes
789 attached printers to be reset. Using
790 lp=port1,port2,... specifies the parallel ports
791 to associate lp devices with, starting with
792 lp0. A port specification may be 'none' to skip
793 that lp device, or a parport name such as
794 'parport0'. Specifying 'lp=auto' instead of a
795 port specification list means that device IDs
796 from each port should be examined, to see if
797 an IEEE 1284-compliant printer is attached; if
798 so, the driver will manage that printer.
799 See also header of drivers/char/lp.c.
800
801 lpj=n [KNL]
802 Sets loops_per_jiffy to given constant, thus avoiding
803 time-consuming boot-time autodetection (up to 250 ms per
804 CPU). 0 enables autodetection (default). To determine
805 the correct value for your kernel, boot with normal
806 autodetection and see what value is printed. Note that
807 on SMP systems the preset will be applied to all CPUs,
808 which is likely to cause problems if your CPUs need
809 significantly divergent settings. An incorrect value
810 will cause delays in the kernel to be wrong, leading to
811 unpredictable I/O errors and other breakage. Although
812 unlikely, in the extreme case this might damage your
813 hardware.
814
815 ltpc= [NET]
816 Format: <io>,<irq>,<dma>
817
a9913044
RD
818 mac5380= [HW,SCSI] Format:
819 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 820
a9913044
RD
821 mac53c9x= [HW,SCSI] Format:
822 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 823
a9913044
RD
824 machvec= [IA64] Force the use of a particular machine-vector
825 (machvec) in a generic kernel.
826 Example: machvec=hpzx1_swiotlb
1da177e4 827
a9913044
RD
828 mad16= [HW,OSS] Format:
829 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
830
831 maui= [HW,OSS]
832 Format: <io>,<irq>
a9913044
RD
833
834 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
835 be mounted
836 Format: <1-256>
837
838 maxcpus= [SMP] Maximum number of processors that an SMP kernel
839 should make use of
840
2b2c3750
BP
841 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
842 equal to this physical address is ignored.
843
a9913044 844 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
845 Should be between 1 and 2^32-1.
846
847 max_report_luns=
a9913044 848 [SCSI] Maximum number of LUNs received.
1da177e4
LT
849 Should be between 1 and 16384.
850
851 mca-pentium [BUGS=IA-32]
852
853 mcatest= [IA-64]
854
855 mcd= [HW,CD]
856 Format: <port>,<irq>,<mitsumi_bug_93_wait>
857
858 mcdx= [HW,CD]
859
860 mce [IA-32] Machine Check Exception
861
862 md= [HW] RAID subsystems devices and level
863 See Documentation/md.txt.
a9913044 864
1da177e4
LT
865 mdacon= [MDA]
866 Format: <first>,<last>
867 Specifies range of consoles to be captured by the MDA.
a9913044 868
1da177e4
LT
869 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
870 Amount of memory to be used when the kernel is not able
871 to see the whole system memory or for test.
872 [IA-32] Use together with memmap= to avoid physical
873 address space collisions. Without memmap= PCI devices
874 could be placed at addresses belonging to unused RAM.
875
876 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
877 memory.
878
69cda7b1 879 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
880 E820 memory map, as specified by the user.
881 Such memmap=exactmap lines can be constructed based on
882 BIOS output or other requirements. See the memmap=nn@ss
883 option description.
884
885 memmap=nn[KMG]@ss[KMG]
886 [KNL] Force usage of a specific region of memory
887 Region of memory to be used, from ss to ss+nn.
888
889 memmap=nn[KMG]#ss[KMG]
890 [KNL,ACPI] Mark specific memory as ACPI data.
891 Region of memory to be used, from ss to ss+nn.
892
893 memmap=nn[KMG]$ss[KMG]
894 [KNL,ACPI] Mark specific memory as reserved.
895 Region of memory to be used, from ss to ss+nn.
896
897 meye.*= [HW] Set MotionEye Camera parameters
898 See Documentation/video4linux/meye.txt.
899
900 mga= [HW,DRM]
901
198e2f18
AM
902 migration_cost=
903 [KNL,SMP] debug: override scheduler migration costs
904 Format: <level-1-usecs>,<level-2-usecs>,...
905 This debugging option can be used to override the
906 default scheduler migration cost matrix. The numbers
907 are indexed by 'CPU domain distance'.
908 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
909 box will set up an intra-core migration cost of
910 1 msec, an inter-core migration cost of 2 msecs,
911 and an inter-node migration cost of 3 msecs.
912
913 WARNING: using the wrong values here can break
914 scheduler performance, so it's only for scheduler
915 development purposes, not production environments.
916
917 migration_debug=
918 [KNL,SMP] migration cost auto-detect verbosity
919 Format=<0|1|2>
920 If a system's migration matrix reported at bootup
921 seems erroneous then this option can be used to
922 increase verbosity of the detection process.
923 We default to 0 (no extra messages), 1 will print
924 some more information, and 2 will be really
925 verbose (probably only useful if you also have a
926 serial console attached to the system).
927
928 migration_factor=
929 [KNL,SMP] multiply/divide migration costs by a factor
930 Format=<percent>
931 This debug option can be used to proportionally
932 increase or decrease the auto-detected migration
933 costs for all entries of the migration matrix.
934 E.g. migration_factor=150 will increase migration
935 costs by 50%. (and thus the scheduler will be less
936 eager migrating cache-hot tasks)
937 migration_factor=80 will decrease migration costs
938 by 20%. (thus the scheduler will be more eager to
939 migrate tasks)
940
941 WARNING: using the wrong values here can break
942 scheduler performance, so it's only for scheduler
943 development purposes, not production environments.
944
1da177e4
LT
945 mousedev.tap_time=
946 [MOUSE] Maximum time between finger touching and
947 leaving touchpad surface for touch to be considered
948 a tap and be reported as a left button click (for
949 touchpads working in absolute mode only).
950 Format: <msecs>
951 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
952 reporting absolute coordinates, such as tablets
953 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
954 reporting absolute coordinates, such as tablets
955
956 mpu401= [HW,OSS]
957 Format: <io>,<irq>
958
959 MTD_Partition= [MTD]
960 Format: <name>,<region-number>,<size>,<offset>
961
a9913044
RD
962 MTD_Region= [MTD] Format:
963 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
964
965 mtdparts= [MTD]
966 See drivers/mtd/cmdline.c.
967
968 mtouchusb.raw_coordinates=
a9913044
RD
969 [HW] Make the MicroTouch USB driver use raw coordinates
970 ('y', default) or cooked coordinates ('n')
1da177e4
LT
971
972 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
973
974 NCR_D700= [HW,SCSI]
975 See header of drivers/scsi/NCR_D700.c.
976
977 ncr5380= [HW,SCSI]
978
979 ncr53c400= [HW,SCSI]
980
981 ncr53c400a= [HW,SCSI]
982
983 ncr53c406a= [HW,SCSI]
984
985 ncr53c8xx= [HW,SCSI]
986
987 netdev= [NET] Network devices parameters
988 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
989 Note that mem_start is often overloaded to mean
990 something different and driver-specific.
a9913044
RD
991 This usage is only documented in each driver source
992 file if at all.
993
1da177e4
LT
994 nfsaddrs= [NFS]
995 See Documentation/nfsroot.txt.
996
997 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
998 See Documentation/nfsroot.txt.
999
a72b4422
TM
1000 nfs.callback_tcpport=
1001 [NFS] set the TCP port on which the NFSv4 callback
1002 channel should listen.
1003
58df095b
TM
1004 nfs.idmap_cache_timeout=
1005 [NFS] set the maximum lifetime for idmapper cache
1006 entries.
1007
1da177e4
LT
1008 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1009
1010 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1011 emulation library even if a 387 maths coprocessor
1012 is present.
1013
a9913044
RD
1014 noalign [KNL,ARM]
1015
1da177e4
LT
1016 noapic [SMP,APIC] Tells the kernel to not make use of any
1017 IOAPICs that may be present in the system.
1018
1019 noasync [HW,M68K] Disables async and sync negotiation for
1020 all devices.
1021
1022 nobats [PPC] Do not use BATs for mapping kernel lowmem
1023 on "Classic" PPC cores.
1024
1025 nocache [ARM]
a9913044 1026
1da177e4
LT
1027 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1028
1029 noexec [IA-64]
1030
a9913044 1031 noexec [IA-32,X86-64]
1da177e4
LT
1032 noexec=on: enable non-executable mappings (default)
1033 noexec=off: disable nn-executable mappings
1034
4f886511
CE
1035 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1036 register save and restore. The kernel will only save
1037 legacy floating-point registers on task switch.
1da177e4
LT
1038
1039 nohlt [BUGS=ARM]
a9913044 1040
1da177e4
LT
1041 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1042 instruction doesn't work correctly and not to
1043 use it.
1044
1045 nohalt [IA-64] Tells the kernel not to use the power saving
1046 function PAL_HALT_LIGHT when idle. This increases
1047 power-consumption. On the positive side, it reduces
1048 interrupt wake-up latency, which may improve performance
1049 in certain environments such as networked servers or
1050 real-time systems.
1051
1052 noirqdebug [IA-32] Disables the code which attempts to detect and
1053 disable unhandled interrupt sources.
1054
1055 noisapnp [ISAPNP] Disables ISA PnP code.
1056
1057 noinitrd [RAM] Tells the kernel not to load any configured
1058 initial RAM disk.
1059
1060 nointroute [IA-64]
1061
1062 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1063
1064 noltlbs [PPC] Do not use large page/tlb entries for kernel
1065 lowmem mapping on PPC40x.
1066
312f1f01
H
1067 nomca [IA-64] Disable machine check abort handling
1068
abe37e5a
H
1069 nomce [IA-32] Machine Check Exception
1070
1da177e4
LT
1071 noresidual [PPC] Don't use residual data on PReP machines.
1072
a9913044
RD
1073 noresume [SWSUSP] Disables resume and restores original swap
1074 space.
1075
1da177e4
LT
1076 no-scroll [VGA] Disables scrollback.
1077 This is required for the Braillex ib80-piezo Braille
1078 reader made by F.H. Papenmeier (Germany).
1079
1080 nosbagart [IA-64]
1081
4f886511
CE
1082 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1083
1da177e4
LT
1084 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1085
1086 nosync [HW,M68K] Disables sync negotiation for all devices.
1087
1088 notsc [BUGS=IA-32] Disable Time Stamp Counter
1089
1090 nousb [USB] Disable the USB subsystem
1091
1092 nowb [ARM]
a9913044 1093
a61c2d78
DJ
1094 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1095
1da177e4
LT
1096 opl3= [HW,OSS]
1097 Format: <io>
1098
1099 opl3sa= [HW,OSS]
1100 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1101
a9913044
RD
1102 opl3sa2= [HW,OSS] Format:
1103 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1104
1da177e4
LT
1105 oprofile.timer= [HW]
1106 Use timer interrupt instead of performance counters
1107
1108 optcd= [HW,CD]
1109 Format: <io>
1110
1111 osst= [HW,SCSI] SCSI Tape Driver
1112 Format: <buffer_size>,<write_threshold>
1113 See also Documentation/scsi/st.txt.
1114
1115 panic= [KNL] Kernel behaviour on panic
1116 Format: <timeout>
1117
1118 parkbd.port= [HW] Parallel port number the keyboard adapter is
1119 connected to, default is 0.
1120 Format: <parport#>
1121 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1122 0 for XT, 1 for AT (default is AT).
a9913044
RD
1123 Format: <mode>
1124
1125 parport= [HW,PPT] Specify parallel ports. 0 disables.
1126 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1127 Use 'auto' to force the driver to use any
1128 IRQ/DMA settings detected (the default is to
1129 ignore detected IRQ/DMA settings because of
1130 possible conflicts). You can specify the base
1131 address, IRQ, and DMA settings; IRQ and DMA
1132 should be numbers, or 'auto' (for using detected
1133 settings on that particular port), or 'nofifo'
1134 (to avoid using a FIFO even if it is detected).
1135 Parallel ports are assigned in the order they
1136 are specified on the command line, starting
1137 with parport0.
1138
1139 parport_init_mode= [HW,PPT]
1140 Configure VIA parallel port to operate in
1141 a specific mode. This is necessary on Pegasos
1142 computer where firmware has no options for setting
1143 up parallel port mode and sets it to spp.
1144 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1145 Format: [spp|ps2|epp|ecp|ecpepp]
1146
a9913044
RD
1147 pas2= [HW,OSS] Format:
1148 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1149
1da177e4
LT
1150 pas16= [HW,SCSI]
1151 See header of drivers/scsi/pas16.c.
1152
dd287796
AM
1153 pause_on_oops=
1154 Halt all CPUs after the first oops has been printed for
1155 the specified number of seconds. This is to be used if
1156 your oopses keep scrolling off the screen.
1157
1da177e4
LT
1158 pcbit= [HW,ISDN]
1159
1160 pcd. [PARIDE]
1161 See header of drivers/block/paride/pcd.c.
1162 See also Documentation/paride.txt.
1163
a9913044
RD
1164 pci=option[,option...] [PCI] various PCI subsystem options:
1165 off [IA-32] don't probe for the PCI bus
1166 bios [IA-32] force use of PCI BIOS, don't access
1167 the hardware directly. Use this if your machine
1168 has a non-standard PCI host bridge.
1169 nobios [IA-32] disallow use of PCI BIOS, only direct
1170 hardware access methods are allowed. Use this
1171 if you experience crashes upon bootup and you
1172 suspect they are caused by the BIOS.
1173 conf1 [IA-32] Force use of PCI Configuration
1174 Mechanism 1.
1175 conf2 [IA-32] Force use of PCI Configuration
1176 Mechanism 2.
61be6d66
BH
1177 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1178 Configuration
309e57df
MW
1179 nomsi [MSI] If the PCI_MSI kernel config parameter is
1180 enabled, this kernel boot option can be used to
1181 disable the use of MSI interrupts system-wide.
a9913044
RD
1182 nosort [IA-32] Don't sort PCI devices according to
1183 order given by the PCI BIOS. This sorting is
1184 done to get a device order compatible with
1185 older kernels.
1186 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1187 routing table. These calls are known to be buggy
1188 on several machines and they hang the machine
1189 when used, but on other computers it's the only
1190 way to get the interrupt routing table. Try
1191 this option if the kernel is unable to allocate
1192 IRQs or discover secondary PCI buses on your
1193 motherboard.
1194 rom [IA-32] Assign address space to expansion ROMs.
1195 Use with caution as certain devices share
1196 address decoders between ROMs and other
1197 resources.
1198 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1199 assigned automatically to PCI devices. You can
1200 make the kernel exclude IRQs of your ISA cards
1201 this way.
120bb424 1202 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1203 of the PIRQ table (normally generated
1204 by the BIOS) if it is outside the
1205 F0000h-100000h range.
1206 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1207 useful if the kernel is unable to find your
1208 secondary buses and you want to tell it
1209 explicitly which ones they are.
1210 assign-busses [IA-32] Always assign all PCI bus
1211 numbers ourselves, overriding
1212 whatever the firmware may have done.
1213 usepirqmask [IA-32] Honor the possible IRQ mask stored
1214 in the BIOS $PIR table. This is needed on
1215 some systems with broken BIOSes, notably
1216 some HP Pavilion N5400 and Omnibook XE3
1217 notebooks. This will have no effect if ACPI
1218 IRQ routing is enabled.
1219 noacpi [IA-32] Do not use ACPI for IRQ routing
1220 or for PCI scanning.
1221 routeirq Do IRQ routing for all PCI devices.
1222 This is normally done in pci_enable_device(),
1223 so this option is a temporary workaround
1224 for broken drivers that don't call it.
1225 firmware [ARM] Do not re-enumerate the bus but instead
1226 just use the configuration from the
1227 bootloader. This is currently used on
1228 IXP2000 systems where the bus has to be
1229 configured a certain way for adjunct CPUs.
1da177e4
LT
1230
1231 pcmv= [HW,PCMCIA] BadgePAD 4
1232
1233 pd. [PARIDE]
1234 See Documentation/paride.txt.
1235
1236 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1237 boot time.
1238 Format: { 0 | 1 }
1239 See arch/parisc/kernel/pdc_chassis.c
1240
1241 pf. [PARIDE]
1242 See Documentation/paride.txt.
1243
1244 pg. [PARIDE]
1245 See Documentation/paride.txt.
1246
1247 pirq= [SMP,APIC] Manual mp-table setup
1248 See Documentation/i386/IO-APIC.txt.
1249
1250 plip= [PPT,NET] Parallel port network link
1251 Format: { parport<nr> | timid | 0 }
1252 See also Documentation/parport.txt.
1253
1254 pnpacpi= [ACPI]
1255 { off }
1256
1257 pnpbios= [ISAPNP]
1258 { on | off | curr | res | no-curr | no-res }
1259
1260 pnp_reserve_irq=
1261 [ISAPNP] Exclude IRQs for the autoconfiguration
1262
1263 pnp_reserve_dma=
1264 [ISAPNP] Exclude DMAs for the autoconfiguration
1265
1266 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1267 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1268
1269 pnp_reserve_mem=
a9913044
RD
1270 [ISAPNP] Exclude memory regions for the
1271 autoconfiguration.
1da177e4
LT
1272 Ranges are in pairs (memory base and size).
1273
1274 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1275 Format: [schedule,]<number>
1276 Param: "schedule" - profile schedule points.
1277 Param: <number> - step/bucket size as a power of 2 for
1278 statistical time based profiling.
1da177e4 1279
a9913044 1280 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1281 Limit processor to maximum C-state
1282 max_cstate=9 overrides any DMI blacklist limit.
1283
41c0d868
LB
1284 processor.nocst [HW,ACPI]
1285 Ignore the _CST method to determine C-states,
1286 instead using the legacy FADT method
1287
1da177e4
LT
1288 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1289 before loading.
1290 See Documentation/ramdisk.txt.
1291
a9913044
RD
1292 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1293 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1294 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1295 per second.
a9913044
RD
1296 psmouse.resetafter= [HW,MOUSE]
1297 Try to reset the device after so many bad packets
1da177e4
LT
1298 (0 = never).
1299 psmouse.resolution=
1300 [HW,MOUSE] Set desired mouse resolution, in dpi.
1301 psmouse.smartscroll=
a9913044 1302 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1303 0 = disabled, 1 = enabled (default).
1304
1305 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1306 Format:
1307 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1308
1309 pt. [PARIDE]
1310 See Documentation/paride.txt.
1311
1312 quiet= [KNL] Disable log messages
a9913044 1313
1da177e4
LT
1314 r128= [HW,DRM]
1315
1316 raid= [HW,RAID]
1317 See Documentation/md.txt.
1318
1319 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1320 See Documentation/ramdisk.txt.
1321
a9913044 1322 ramdisk_blocksize= [RAM]
1da177e4 1323 See Documentation/ramdisk.txt.
a9913044 1324
1da177e4
LT
1325 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1326 New name for the ramdisk parameter.
1327 See Documentation/ramdisk.txt.
1328
21a1ea9e
DS
1329 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1330 RCU callbacks to process in one batch.
1331
1332 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1333 RCU callbacks over which batch limiting is disabled.
1334
1335 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1336 RCU callbacks below which batch limiting is re-enabled.
1337
1338 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1339 RCU callbacks to queued before forcing reschedule
1340 on all cpus.
1341
ffdfc409
OJ
1342 rdinit= [KNL]
1343 Format: <full_path>
1344 Run specified binary instead of /init from the ramdisk,
1345 used for early userspace startup. See initrd.
1346
1da177e4
LT
1347 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1348 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1349 See arch/*/kernel/reboot.c.
1350
1351 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1352
a9913044
RD
1353 resume= [SWSUSP]
1354 Specify the partition device for software suspend
1da177e4
LT
1355
1356 rhash_entries= [KNL,NET]
1357 Set number of hash buckets for route cache
1358
1359 riscom8= [HW,SERIAL]
1360 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1361
1362 ro [KNL] Mount root device read-only on boot
1363
1364 root= [KNL] Root filesystem
1365
1366 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1367 mount the root filesystem
1368
1369 rootflags= [KNL] Set root filesystem mount option string
1370
1371 rootfstype= [KNL] Set root filesystem type
1372
1373 rw [KNL] Mount root device read-write on boot
1374
1375 S [KNL] Run init in single mode
1376
1377 sa1100ir [NET]
1378 See drivers/net/irda/sa1100_ir.c.
1379
1380 sb= [HW,OSS]
1381 Format: <io>,<irq>,<dma>,<dma2>
1382
1383 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1384
1da177e4
LT
1385 sbpcd= [HW,CD] Soundblaster CD adapter
1386 Format: <io>,<type>
1387 See a comment before function sbpcd_setup() in
1388 drivers/cdrom/sbpcd.c.
1389
1390 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1391 Format: <io>[,<timeout>[,<isapnp>]]
1392
1393 scsi_debug_*= [SCSI]
1394 See drivers/scsi/scsi_debug.c.
1395
1396 scsi_default_dev_flags=
1397 [SCSI] SCSI default device flags
1398 Format: <integer>
1399
1400 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1401 Format: <vendor>:<model>:<flags>
1402 (flags are integer value)
1403
1404 scsi_logging= [SCSI]
1405
1406 selinux [SELINUX] Disable or enable SELinux at boot time.
1407 Format: { "0" | "1" }
1408 See security/selinux/Kconfig help text.
1409 0 -- disable.
1410 1 -- enable.
1411 Default value is set via kernel config option.
1412 If enabled at boot time, /selinux/disable can be used
1413 later to disable prior to initial policy load.
1414
4e5ab4cb
JM
1415 selinux_compat_net =
1416 [SELINUX] Set initial selinux_compat_net flag value.
1417 Format: { "0" | "1" }
1418 0 -- use new secmark-based packet controls
1419 1 -- use legacy packet controls
1420 Default value is 0 (preferred).
1421 Value can be changed at runtime via
1422 /selinux/compat_net.
1423
1da177e4
LT
1424 serialnumber [BUGS=IA-32]
1425
a9913044
RD
1426 sg_def_reserved_size= [SCSI]
1427
1da177e4
LT
1428 sgalaxy= [HW,OSS]
1429 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1430
1431 shapers= [NET]
1432 Maximal number of shapers.
a9913044 1433
1da177e4
LT
1434 sim710= [SCSI,HW]
1435 See header of drivers/scsi/sim710.c.
1436
1437 simeth= [IA-64]
1438 simscsi=
a9913044 1439
1da177e4
LT
1440 sjcd= [HW,CD]
1441 Format: <io>,<irq>,<dma>
1442 See header of drivers/cdrom/sjcd.c.
1443
1444 slram= [HW,MTD]
1445
1446 smart2= [HW]
1447 Format: <io1>[,<io2>[,...,<io8>]]
1448
1449 snd-ad1816a= [HW,ALSA]
1450
1451 snd-ad1848= [HW,ALSA]
1452
1453 snd-ali5451= [HW,ALSA]
1454
1455 snd-als100= [HW,ALSA]
1456
1457 snd-als4000= [HW,ALSA]
1458
1459 snd-azt2320= [HW,ALSA]
1460
1461 snd-cmi8330= [HW,ALSA]
1462
1463 snd-cmipci= [HW,ALSA]
1464
1465 snd-cs4231= [HW,ALSA]
1466
1467 snd-cs4232= [HW,ALSA]
1468
1469 snd-cs4236= [HW,ALSA]
1470
1471 snd-cs4281= [HW,ALSA]
1472
1473 snd-cs46xx= [HW,ALSA]
1474
1475 snd-dt019x= [HW,ALSA]
1476
1477 snd-dummy= [HW,ALSA]
1478
1479 snd-emu10k1= [HW,ALSA]
1480
1481 snd-ens1370= [HW,ALSA]
1482
1483 snd-ens1371= [HW,ALSA]
1484
1485 snd-es968= [HW,ALSA]
1486
1487 snd-es1688= [HW,ALSA]
1488
1489 snd-es18xx= [HW,ALSA]
1490
1491 snd-es1938= [HW,ALSA]
1492
1493 snd-es1968= [HW,ALSA]
1494
1495 snd-fm801= [HW,ALSA]
1496
1497 snd-gusclassic= [HW,ALSA]
1498
1499 snd-gusextreme= [HW,ALSA]
1500
1501 snd-gusmax= [HW,ALSA]
1502
1503 snd-hdsp= [HW,ALSA]
1504
1505 snd-ice1712= [HW,ALSA]
1506
1507 snd-intel8x0= [HW,ALSA]
1508
1509 snd-interwave= [HW,ALSA]
1510
1511 snd-interwave-stb=
1512 [HW,ALSA]
1513
1514 snd-korg1212= [HW,ALSA]
1515
1516 snd-maestro3= [HW,ALSA]
1517
1518 snd-mpu401= [HW,ALSA]
1519
1520 snd-mtpav= [HW,ALSA]
1521
1522 snd-nm256= [HW,ALSA]
1523
1524 snd-opl3sa2= [HW,ALSA]
1525
1526 snd-opti92x-ad1848=
1527 [HW,ALSA]
1528
1529 snd-opti92x-cs4231=
1530 [HW,ALSA]
1531
1532 snd-opti93x= [HW,ALSA]
1533
1534 snd-pmac= [HW,ALSA]
1535
1536 snd-rme32= [HW,ALSA]
1537
1538 snd-rme96= [HW,ALSA]
1539
1540 snd-rme9652= [HW,ALSA]
1541
1542 snd-sb8= [HW,ALSA]
1543
1544 snd-sb16= [HW,ALSA]
1545
1546 snd-sbawe= [HW,ALSA]
1547
1548 snd-serial= [HW,ALSA]
1549
1550 snd-sgalaxy= [HW,ALSA]
1551
1552 snd-sonicvibes= [HW,ALSA]
1553
1554 snd-sun-amd7930=
1555 [HW,ALSA]
1556
1557 snd-sun-cs4231= [HW,ALSA]
1558
1559 snd-trident= [HW,ALSA]
1560
1561 snd-usb-audio= [HW,ALSA,USB]
1562
1563 snd-via82xx= [HW,ALSA]
1564
1565 snd-virmidi= [HW,ALSA]
1566
1567 snd-wavefront= [HW,ALSA]
1568
1569 snd-ymfpci= [HW,ALSA]
a9913044 1570
1da177e4
LT
1571 sonicvibes= [HW,OSS]
1572 Format: <reverb>
a9913044 1573
1da177e4
LT
1574 sonycd535= [HW,CD]
1575 Format: <io>[,<irq>]
1576
1577 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1578 See Documentation/sonypi.txt
1579
1580 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1581 See Documentation/specialix.txt.
1582
1583 spia_io_base= [HW,MTD]
1584 spia_fio_base=
1585 spia_pedr=
1586 spia_peddr=
1587
1588 sscape= [HW,OSS]
1589 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1590
1da177e4
LT
1591 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1592 See Documentation/scsi/st.txt.
1593
1594 st0x= [HW,SCSI]
1595 See header of drivers/scsi/seagate.c.
1596
1597 sti= [PARISC,HW]
1598 Format: <num>
1599 Set the STI (builtin display/keyboard on the HP-PARISC
1600 machines) console (graphic card) which should be used
1601 as the initial boot-console.
1602 See also comment in drivers/video/console/sticore.c.
1603
1604 sti_font= [HW]
1605 See comment in drivers/video/console/sticore.c.
1606
1607 stifb= [HW]
1608 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1609
1da177e4 1610 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1611
1da177e4
LT
1612 switches= [HW,M68k]
1613
1614 sym53c416= [HW,SCSI]
1615 See header of drivers/scsi/sym53c416.c.
1616
1617 t128= [HW,SCSI]
1618 See header of drivers/scsi/t128.c.
1619
1620 tdfx= [HW,DRM]
1621
1622 thash_entries= [KNL,NET]
1623 Set number of hash buckets for TCP connection
1624
1625 time Show timing data prefixed to each printk message line
1626
734efb46
JS
1627 clocksource= [GENERIC_TIME] Override the default clocksource
1628 Override the default clocksource and use the clocksource
1629 with the name specified.
1630
1da177e4
LT
1631 tipar.timeout= [HW,PPT]
1632 Set communications timeout in tenths of a second
1633 (default 15).
1634
1635 tipar.delay= [HW,PPT]
1636 Set inter-bit delay in microseconds (default 10).
1637
1638 tmc8xx= [HW,SCSI]
1639 See header of drivers/scsi/seagate.c.
1640
1641 tmscsim= [HW,SCSI]
1642 See comment before function dc390_setup() in
1643 drivers/scsi/tmscsim.c.
1644
1645 tp720= [HW,PS2]
1646
1647 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1648 Format:
1649 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1650
1da177e4
LT
1651 tsdev.xres= [TS] Horizontal screen resolution.
1652 tsdev.yres= [TS] Vertical screen resolution.
1653
a9913044
RD
1654 turbografx.map[2|3]= [HW,JOY]
1655 TurboGraFX parallel port interface
1656 Format:
1657 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1658 See also Documentation/input/joystick-parport.txt
1659
1660 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1661 See header of drivers/scsi/u14-34f.c.
1662
1663 uart401= [HW,OSS]
1664 Format: <io>,<irq>
1665
1666 uart6850= [HW,OSS]
1667 Format: <io>,<irq>
1668
1da177e4
LT
1669 usbhid.mousepoll=
1670 [USBHID] The interval which mice are to be polled at.
a9913044 1671
e6e5494c
IM
1672 vdso= [IA-32]
1673 vdso=1: enable VDSO (default)
1674 vdso=0: disable VDSO mapping
1675
1da177e4
LT
1676 video= [FB] Frame buffer configuration
1677 See Documentation/fb/modedb.txt.
1678
1679 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1680 See Documentation/i386/boot.txt and
1681 Documentation/svga.txt.
1da177e4
LT
1682 Use vga=ask for menu.
1683 This is actually a boot loader parameter; the value is
1684 passed to the kernel using a special protocol.
1685
a9913044 1686 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1687 size of <nn>. This can be used to increase the
1688 minimum size (128MB on x86). It can also be used to
1689 decrease the size and leave more room for directly
1690 mapped kernel RAM.
1691
1692 vmhalt= [KNL,S390]
1693
a9913044
RD
1694 vmpoff= [KNL,S390]
1695
1da177e4
LT
1696 waveartist= [HW,OSS]
1697 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1698
1da177e4
LT
1699 wd33c93= [HW,SCSI]
1700 See header of drivers/scsi/wd33c93.c.
1701
1702 wd7000= [HW,SCSI]
1703 See header of drivers/scsi/wd7000.c.
1704
1705 wdt= [WDT] Watchdog
1706 See Documentation/watchdog/watchdog.txt.
1707
1708 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1709 xd_geo= See header of drivers/block/xd.c.
1710
1711 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1712 Format:
1713 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1714
a62eaf15
AK
1715 norandmaps Don't use address space randomization
1716 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1717
1da177e4 1718
a9913044 1719______________________________________________________________________
1da177e4
LT
1720
1721TODO:
1722
1723 Add documentation for ALSA options.
1724 Add more DRM drivers.