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1February 2003 Kernel Parameters v2.5.59
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
a9913044 20The text in square brackets at the beginning of the description states the
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21restrictions on the kernel for the said kernel parameter to be valid. The
22restrictions referred to are that the relevant option is valid if:
23
24 ACPI ACPI support is enabled.
25 ALSA ALSA sound support is enabled.
26 APIC APIC support is enabled.
27 APM Advanced Power Management support is enabled.
28 AX25 Appropriate AX.25 support is enabled.
29 CD Appropriate CD support is enabled.
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30 DEVFS devfs support is enabled.
31 DRM Direct Rendering Management support is enabled.
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32 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
33 EFI EFI Partitioning (GPT) is enabled
34 EIDE EIDE/ATAPI support is enabled.
35 FB The frame buffer device is enabled.
36 HW Appropriate hardware is enabled.
37 IA-32 IA-32 aka i386 architecture is enabled.
38 IA-64 IA-64 architecture is enabled.
39 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 40 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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41 ISAPNP ISA PnP code is enabled.
42 ISDN Appropriate ISDN support is enabled.
43 JOY Appropriate joystick support is enabled.
44 LP Printer support is enabled.
45 LOOP Loopback device support is enabled.
46 M68k M68k architecture is enabled.
47 These options have more detailed description inside of
48 Documentation/m68k/kernel-options.txt.
49 MCA MCA bus support is enabled.
50 MDA MDA console support is enabled.
51 MOUSE Appropriate mouse support is enabled.
52 MTD MTD support is enabled.
53 NET Appropriate network support is enabled.
54 NUMA NUMA support is enabled.
55 NFS Appropriate NFS support is enabled.
56 OSS OSS sound support is enabled.
57 PARIDE The ParIDE subsystem is enabled.
58 PARISC The PA-RISC architecture is enabled.
59 PCI PCI bus support is enabled.
60 PCMCIA The PCMCIA subsystem is enabled.
61 PNP Plug & Play support is enabled.
62 PPC PowerPC architecture is enabled.
63 PPT Parallel port support is enabled.
64 PS2 Appropriate PS/2 support is enabled.
65 RAM RAM disk support is enabled.
66 S390 S390 architecture is enabled.
67 SCSI Appropriate SCSI support is enabled.
68 A lot of drivers has their options described inside of
69 Documentation/scsi/.
70 SELINUX SELinux support is enabled.
71 SERIAL Serial support is enabled.
72 SMP The kernel is an SMP kernel.
73 SPARC Sparc architecture is enabled.
a9913044 74 SWSUSP Software suspend is enabled.
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75 TS Appropriate touchscreen support is enabled.
76 USB USB support is enabled.
77 USBHID USB Human Interface Device support is enabled.
78 V4L Video For Linux support is enabled.
79 VGA The VGA console has been enabled.
80 VT Virtual terminal support is enabled.
81 WDT Watchdog support is enabled.
82 XT IBM PC/XT MFM hard disk support is enabled.
83 X86-64 X86-64 architecture is enabled.
84 More X86-64 boot options can be found in
85 Documentation/x86_64/boot-options.txt .
86
87In addition, the following text indicates that the option:
88
89 BUGS= Relates to possible processor bugs on the said processor.
90 KNL Is a kernel start-up parameter.
91 BOOT Is a boot loader parameter.
92
93Parameters denoted with BOOT are actually interpreted by the boot
94loader, and have no meaning to the kernel directly.
95Do not modify the syntax of boot loader parameters without extreme
96need or coordination with <Documentation/i386/boot.txt>.
97
98Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
99a trailing = on the name of any parameter states that that parameter will
100be entered as an environment variable, whereas its absence indicates that
101it will appear as a kernel argument readable via /proc/cmdline by programs
102running once the system is up.
103
104 53c7xx= [HW,SCSI] Amiga SCSI controllers
105 See header of drivers/scsi/53c7xx.c.
106 See also Documentation/scsi/ncr53c7xx.txt.
107
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108 acpi= [HW,ACPI] Advanced Configuration and Power Interface
109 Format: { force | off | ht | strict | noirq }
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110 force -- enable ACPI if default was off
111 off -- disable ACPI if default was on
112 noirq -- do not use ACPI for IRQ routing
113 ht -- run only enough ACPI to enable Hyper Threading
a9913044 114 strict -- Be less tolerant of platforms that are not
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115 strictly ACPI specification compliant.
116
117 See also Documentation/pm.txt, pci=noacpi
118
119 acpi_sleep= [HW,ACPI] Sleep options
120 Format: { s3_bios, s3_mode }
121 See Documentation/power/video.txt
a9913044 122
1da177e4 123 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 124 Format: { level | edge | high | low }
1da177e4 125
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126 acpi_irq_balance [HW,ACPI]
127 ACPI will balance active IRQs
128 default in APIC mode
1da177e4 129
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130 acpi_irq_nobalance [HW,ACPI]
131 ACPI will not move active IRQs (default)
132 default in PIC mode
1da177e4 133
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134 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
135 use by PCI
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136 Format: <irq>,<irq>...
137
a9913044 138 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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139 Format: <irq>,<irq>...
140
141 acpi_osi= [HW,ACPI] empty param disables _OSI
142
143 acpi_serialize [HW,ACPI] force serialization of AML methods
144
145 acpi_skip_timer_override [HW,ACPI]
146 Recognize and ignore IRQ0/pin2 Interrupt Override.
147 For broken nForce2 BIOS resulting in XT-PIC timer.
148
149 acpi_dbg_layer= [HW,ACPI]
150 Format: <int>
a9913044 151 Each bit of the <int> indicates an ACPI debug layer,
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152 1: enable, 0: disable. It is useful for boot time
153 debugging. After system has booted up, it can be set
154 via /proc/acpi/debug_layer.
155
156 acpi_dbg_level= [HW,ACPI]
157 Format: <int>
a9913044 158 Each bit of the <int> indicates an ACPI debug level,
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159 1: enable, 0: disable. It is useful for boot time
160 debugging. After system has booted up, it can be set
161 via /proc/acpi/debug_level.
162
163 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
164
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165 acpi_generic_hotkey [HW,ACPI]
166 Allow consolidated generic hotkey driver to
a9913044 167 override platform specific driver.
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168 See also Documentation/acpi-hotkey.txt.
169
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170 enable_timer_pin_1 [i386,x86-64]
171 Enable PIN 1 of APIC timer
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172 Can be useful to work around chipset bugs
173 (in particular on some ATI chipsets).
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174 The kernel tries to set a reasonable default.
175
176 disable_timer_pin_1 [i386,x86-64]
177 Disable PIN 1 of APIC timer
178 Can be useful to work around chipset bugs.
179
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180 ad1816= [HW,OSS]
181 Format: <io>,<irq>,<dma>,<dma2>
182 See also Documentation/sound/oss/AD1816.
183
184 ad1848= [HW,OSS]
185 Format: <io>,<irq>,<dma>,<dma2>,<type>
186
187 adlib= [HW,OSS]
188 Format: <io>
a9913044 189
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190 advansys= [HW,SCSI]
191 See header of drivers/scsi/advansys.c.
192
193 advwdt= [HW,WDT] Advantech WDT
194 Format: <iostart>,<iostop>
195
196 aedsp16= [HW,OSS] Audio Excel DSP 16
197 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
198 See also header of sound/oss/aedsp16.c.
a9913044 199
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200 aha152x= [HW,SCSI]
201 See Documentation/scsi/aha152x.txt.
202
203 aha1542= [HW,SCSI]
204 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
205
206 aic7xxx= [HW,SCSI]
207 See Documentation/scsi/aic7xxx.txt.
208
209 aic79xx= [HW,SCSI]
210 See Documentation/scsi/aic79xx.txt.
211
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212 amijoy.map= [HW,JOY] Amiga joystick support
213 Map of devices attached to JOY0DAT and JOY1DAT
214 Format: <a>,<b>
215 See also Documentation/kernel/input/joystick.txt
216
217 analog.map= [HW,JOY] Analog joystick and gamepad support
218 Specifies type or capabilities of an analog joystick
219 connected to one of 16 gameports
220 Format: <type1>,<type2>,..<type16>
221
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222 apc= [HW,SPARC]
223 Power management functions (SPARCstation-4/5 + deriv.)
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224 Format: noidle
225 Disable APC CPU standby support. SPARCstation-Fox does
226 not play well with APC CPU idle - disable it if you have
227 APC and your system crashes randomly.
228
a9913044 229 apic= [APIC,i386] Change the output verbosity whilst booting
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230 Format: { quiet (default) | verbose | debug }
231 Change the amount of debugging information output
232 when initialising the APIC and IO-APIC components.
a9913044 233
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234 apm= [APM] Advanced Power Management
235 See header of arch/i386/kernel/apm.c.
236
237 applicom= [HW]
238 Format: <mem>,<irq>
a9913044 239
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240 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
241 Format: <io>,<irq>,<nodeID>
242
243 ataflop= [HW,M68k]
244
245 atarimouse= [HW,MOUSE] Atari Mouse
246
247 atascsi= [HW,SCSI] Atari SCSI
248
249 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
250 EzKey and similar keyboards
251
252 atkbd.reset= [HW] Reset keyboard during initialization
253
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254 atkbd.set= [HW] Select keyboard code set
255 Format: <int> (2 = AT (default), 3 = PS/2)
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256
257 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
258 keyboards
259
260 atkbd.softraw= [HW] Choose between synthetic and real raw mode
261 Format: <bool> (0 = real, 1 = synthetic (default))
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262
263 atkbd.softrepeat= [HW]
264 Use software keyboard repeat
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265
266 autotest [IA64]
267
268 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
269 Format: <io>,<memsize>,<isapnp>
a9913044 270
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271 aztcd= [HW,CD] Aztech CD268 CDROM driver
272 Format: <io>,0x79 (?)
273
274 baycom_epp= [HW,AX25]
275 Format: <io>,<mode>
a9913044 276
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277 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
278 Format: <io>,<mode>
279 See header of drivers/net/hamradio/baycom_par.c.
280
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281 baycom_ser_fdx= [HW,AX25]
282 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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283 Format: <io>,<irq>,<mode>[,<baud>]
284 See header of drivers/net/hamradio/baycom_ser_fdx.c.
285
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286 baycom_ser_hdx= [HW,AX25]
287 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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288 Format: <io>,<irq>,<mode>
289 See header of drivers/net/hamradio/baycom_ser_hdx.c.
290
291 blkmtd_device= [HW,MTD]
292 blkmtd_erasesz=
293 blkmtd_ro=
294 blkmtd_bs=
295 blkmtd_count=
296
297 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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298 bttv.radio= Most important insmod options are available as
299 kernel args too.
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300 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
301 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
302
303 BusLogic= [HW,SCSI]
304 See drivers/scsi/BusLogic.c, comment before function
305 BusLogic_ParseDriverOptions().
306
307 c101= [NET] Moxa C101 synchronous serial card
308
309 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
310 Sometimes CPU hardware bugs make them report the cache
311 size incorrectly. The kernel will attempt work arounds
312 to fix known problems, but for some CPUs it is not
313 possible to determine what the correct size should be.
314 This option provides an override for these situations.
315
316 cdu31a= [HW,CD]
317 Format: <io>,<irq>[,PAS]
318 See header of drivers/cdrom/cdu31a.c.
319
320 chandev= [HW,NET] Generic channel device initialisation
321
322 checkreqprot [SELINUX] Set initial checkreqprot flag value.
323 Format: { "0" | "1" }
324 See security/selinux/Kconfig help text.
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325 0 -- check protection applied by kernel (includes
326 any implied execute protection).
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327 1 -- check protection requested by application.
328 Default value is set via a kernel config option.
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329 Value can be changed at runtime via
330 /selinux/checkreqprot.
331
332 clock= [BUGS=IA-32,HW] gettimeofday timesource override.
1da177e4 333 Forces specified timesource (if avaliable) to be used
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334 when calculating gettimeofday(). If specicified
335 timesource is not avalible, it defaults to PIT.
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336 Format: { pit | tsc | cyclone | pmtmr }
337
338 hpet= [IA-32,HPET] option to disable HPET and use PIT.
339 Format: disable
340
341 cm206= [HW,CD]
342 Format: { auto | [<io>,][<irq>] }
343
344 com20020= [HW,NET] ARCnet - COM20020 chipset
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345 Format:
346 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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347
348 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
349 Format: <io>[,<irq>]
350
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351 com90xx= [HW,NET]
352 ARCnet - COM90xx chipset (memory-mapped buffers)
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353 Format: <io>[,<irq>[,<memstart>]]
354
355 condev= [HW,S390] console device
356 conmode=
a9913044 357
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358 console= [KNL] Output console device and options.
359
360 tty<n> Use the virtual console device <n>.
361
362 ttyS<n>[,options]
363 Use the specified serial port. The options are of
364 the form "bbbbpn", where "bbbb" is the baud rate,
365 "p" is parity ("n", "o", or "e"), and "n" is bits.
366 Default is "9600n8".
367
368 See also Documentation/serial-console.txt.
369
370 uart,io,<addr>[,options]
371 uart,mmio,<addr>[,options]
372 Start an early, polled-mode console on the 8250/16550
373 UART at the specified I/O port or MMIO address,
374 switching to the matching ttyS device later. The
375 options are the same as for ttyS, above.
376
377 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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378 Format:
379 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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380
381 cpia_pp= [HW,PPT]
382 Format: { parport<nr> | auto | none }
383
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384 crashkernel=nn[KMG]@ss[KMG]
385 [KNL] Reserve a chunk of physical memory to
386 hold a kernel to switch to with kexec on panic.
387
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388 cs4232= [HW,OSS]
389 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
390
391 cs89x0_dma= [HW,NET]
392 Format: <dma>
393
394 cs89x0_media= [HW,NET]
395 Format: { rj45 | aui | bnc }
a9913044 396
1da177e4 397 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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398
399 dasd= [HW,NET]
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400 See header of drivers/s390/block/dasd_devmap.c.
401
402 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
403 (one device per port)
404 Format: <port#>,<type>
405 See also Documentation/input/joystick-parport.txt
406
407 debug [KNL] Enable kernel debugging (events log level).
408
409 decnet= [HW,NET]
410 Format: <area>[,<node>]
411 See also Documentation/networking/decnet.txt.
412
413 devfs= [DEVFS]
414 See Documentation/filesystems/devfs/boot-options.
415
416 dhash_entries= [KNL]
417 Set number of hash buckets for dentry cache.
a9913044 418
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419 digi= [HW,SERIAL]
420 IO parameters + enable/disable command.
421
422 digiepca= [HW,SERIAL]
423 See drivers/char/README.epca and
424 Documentation/digiepca.txt.
425
426 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
427 support available.
428 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
429
430 dmasound= [HW,OSS] Sound subsystem buffers
431
432 dscc4.setup= [NET]
433
434 dtc3181e= [HW,SCSI]
435
a9913044 436 earlyprintk= [IA-32,X86-64]
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437 earlyprintk=vga
438 earlyprintk=serial[,ttySn[,baudrate]]
439
a9913044 440 Append ",keep" to not disable it when the real console
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441 takes over.
442
443 Only vga or serial at a time, not both.
444
445 Currently only ttyS0 and ttyS1 are supported.
446
447 Interaction with the standard serial driver is not
448 very good.
449
450 The VGA output is eventually overwritten by the real
451 console.
452
453 eata= [HW,SCSI]
454
455 eda= [HW,PS2]
456
457 edb= [HW,PS2]
458
459 edd= [EDD]
460 Format: {"of[f]" | "sk[ipmbr]"}
461 See comment in arch/i386/boot/edd.S
462
a9913044 463 eicon= [HW,ISDN]
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464 Format: <id>,<membase>,<irq>
465
466 eisa_irq_edge= [PARISC,HW]
467 See header of drivers/parisc/eisa.c.
468
469 elanfreq= [IA-32]
470 See comment before function elanfreq_setup() in
471 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
472
473 elevator= [IOSCHED]
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474 Format: {"as" | "cfq" | "deadline" | "noop"}
475 See Documentation/block/as-iosched.txt and
476 Documentation/block/deadline-iosched.txt for details.
477
aac04b32 478 elfcorehdr= [IA-32, X86_64]
a9913044 479 Specifies physical address of start of kernel core
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480 image elf header. Generally kexec loader will
481 pass this option to capture kernel.
482 See Documentation/kdump/kdump.txt for details.
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483
484 enforcing [SELINUX] Set initial enforcing status.
485 Format: {"0" | "1"}
486 See security/selinux/Kconfig help text.
487 0 -- permissive (log only, no denials).
488 1 -- enforcing (deny and log).
489 Default value is 0.
490 Value can be changed at runtime via /selinux/enforce.
491
492 es1370= [HW,OSS]
493 Format: <lineout>[,<micbias>]
494 See also header of sound/oss/es1370.c.
495
496 es1371= [HW,OSS]
497 Format: <spdif>,[<nomix>,[<amplifier>]]
498 See also header of sound/oss/es1371.c.
a9913044 499
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500 ether= [HW,NET] Ethernet cards parameters
501 This option is obsoleted by the "netdev=" option, which
502 has equivalent usage. See its documentation for details.
503
504 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
505 Format: <io>[,<irq>]
506
507 fd_mcs= [HW,SCSI]
508 See header of drivers/scsi/fd_mcs.c.
509
510 fdomain= [HW,SCSI]
511 See header of drivers/scsi/fdomain.c.
512
513 floppy= [HW]
514 See Documentation/floppy.txt.
515
516 ftape= [HW] Floppy Tape subsystem debugging options.
517 See Documentation/ftape.txt.
518
519 gamecon.map[2|3]=
520 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
521 support via parallel port (up to 5 devices per port)
522 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
523 See also Documentation/input/joystick-parport.txt
524
525 gamma= [HW,DRM]
526
527 gdth= [HW,SCSI]
528 See header of drivers/scsi/gdth.c.
529
530 gpt [EFI] Forces disk with valid GPT signature but
531 invalid Protective MBR to be treated as GPT.
532
533 gscd= [HW,CD]
534 Format: <io>
535
536 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
537
538 gus= [HW,OSS]
539 Format: <io>,<irq>,<dma>,<dma16>
a9913044 540
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541 gvp11= [HW,SCSI]
542
543 hashdist= [KNL,NUMA] Large hashes allocated during boot
544 are distributed across NUMA nodes. Defaults on
545 for IA-64, off otherwise.
a9913044 546 Format: 0 | 1 (for off | on)
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547
548 hcl= [IA-64] SGI's Hardware Graph compatibility layer
549
550 hd= [EIDE] (E)IDE hard drive subsystem geometry
551 Format: <cyl>,<head>,<sect>
552
553 hd?= [HW] (E)IDE subsystem
554 hd?lun= See Documentation/ide.txt.
555
556 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
557 size of <nn>. This works even on boxes that have no
558 highmem otherwise. This also works to reduce highmem
559 size on bigger boxes.
560
561 hisax= [HW,ISDN]
562 See Documentation/isdn/README.HiSax.
563
564 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
565
566 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
567
568 i8042.direct [HW] Put keyboard port into non-translated mode
569 i8042.dumbkbd [HW] Pretend that controlled can only read data from
570 keyboard and can not control its state
571 (Don't attempt to blink the leds)
572 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 573 i8042.nokbd [HW] Don't check/create keyboard port
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574 i8042.nomux [HW] Don't check presence of an active multiplexing
575 controller
576 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
577 controllers
578 i8042.panicblink=
579 [HW] Frequency with which keyboard LEDs should blink
580 when kernel panics (default is 0.5 sec)
581 i8042.reset [HW] Reset the controller during init and cleanup
582 i8042.unlock [HW] Unlock (ignore) the keylock
583
584 i810= [HW,DRM]
585
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586 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
587 indicates that the driver is running on unsupported
588 hardware.
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589 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
590 does not match list of supported models.
591 i8k.power_status
592 [HW] Report power status in /proc/i8k
593 (disabled by default)
594 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
595 capability is set.
596
597 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
598 See Documentation/mca.txt.
599
600 icn= [HW,ISDN]
601 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
602
603 ide= [HW] (E)IDE subsystem
604 Format: ide=nodma or ide=doubler or ide=reverse
605 See Documentation/ide.txt.
606
607 ide?= [HW] (E)IDE subsystem
608 Format: ide?=noprobe or chipset specific parameters.
609 See Documentation/ide.txt.
a9913044 610
1da177e4
LT
611 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
612 See Documentation/ide.txt.
613
614 idle= [HW]
615 Format: idle=poll or idle=halt
a9913044 616
1da177e4
LT
617 ihash_entries= [KNL]
618 Set number of hash buckets for inode cache.
619
620 in2000= [HW,SCSI]
621 See header of drivers/scsi/in2000.c.
622
623 init= [KNL]
624 Format: <full_path>
625 Run specified binary instead of /sbin/init as init
626 process.
627
628 initcall_debug [KNL] Trace initcalls as they are executed. Useful
629 for working out where the kernel is dying during
630 startup.
631
632 initrd= [BOOT] Specify the location of the initial ramdisk
633
634 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
635 Format: <irq>
636
2bd0fa3b
JB
637 combined_mode= [HW] control which driver uses IDE ports in combined
638 mode: legacy IDE driver, libata, or both
639 (in the libata case, libata.atapi_enabled=1 may be
640 useful as well). Note that using the ide or libata
641 options may affect your device naming (e.g. by
642 changing hdc to sdb).
643 Format: combined (default), ide, or libata
644
1da177e4
LT
645 inttest= [IA64]
646
647 io7= [HW] IO7 for Marvel based alpha systems
648 See comment before marvel_specify_io7 in
649 arch/alpha/kernel/core_marvel.c.
650
651 ip= [IP_PNP]
652 See Documentation/nfsroot.txt.
653
654 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
655 See comment before ip2_setup() in drivers/char/ip2.c.
656
657 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
658 See header of drivers/scsi/ips.c.
659
200803df
AC
660 irqfixup [HW]
661 When an interrupt is not handled search all handlers
662 for it. Intended to get systems with badly broken
663 firmware running.
664
665 irqpoll [HW]
666 When an interrupt is not handled search all handlers
667 for it. Also check all handlers each timer
668 interrupt. Intended to get systems with badly broken
669 firmware running.
670
1da177e4 671 isapnp= [ISAPNP]
a9913044 672 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
673
674 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
675 Format: <cpu number>,...,<cpu number>
676 This option can be used to specify one or more CPUs
677 to isolate from the general SMP balancing and scheduling
678 algorithms. The only way to move a process onto or off
679 an "isolated" CPU is via the CPU affinity syscalls.
680 <cpu number> begins at 0 and the maximum value is
681 "number of CPUs in system - 1".
682
683 This option is the preferred way to isolate CPUs. The
a9913044
RD
684 alternative -- manually setting the CPU mask of all
685 tasks in the system -- can cause problems and
686 suboptimal load balancer performance.
1da177e4
LT
687
688 isp16= [HW,CD]
689 Format: <io>,<irq>,<dma>,<setup>
690
a9913044 691 iucv= [HW,NET]
1da177e4
LT
692
693 js= [HW,JOY] Analog joystick
694 See Documentation/input/joystick.txt.
695
696 keepinitrd [HW,ARM]
697
a9913044 698 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
699 in oops dumps.
700
701 l2cr= [PPC]
702
a9913044
RD
703 lapic [IA-32,APIC] Enable the local APIC even if BIOS
704 disabled it.
1da177e4
LT
705
706 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
707 Format: addr:<io>,irq:<irq>
708
a9913044
RD
709 llsc*= [IA64] See function print_params() in
710 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
711
712 load_ramdisk= [RAM] List of ramdisks to load from floppy
713 See Documentation/ramdisk.txt.
714
a6b25b67
RD
715 lockd.nlm_grace_period=P [NFS] Assign grace period.
716 Format: <integer>
1da177e4 717
a6b25b67
RD
718 lockd.nlm_tcpport=N [NFS] Assign TCP port.
719 Format: <integer>
720
721 lockd.nlm_timeout=T [NFS] Assign timeout value.
722 Format: <integer>
723
724 lockd.nlm_udpport=M [NFS] Assign UDP port.
725 Format: <integer>
1da177e4
LT
726
727 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
728 Format: <irq>
729
730 loglevel= All Kernel Messages with a loglevel smaller than the
731 console loglevel will be printed to the console. It can
732 also be changed with klogd or other programs. The
733 loglevels are defined as follows:
734
735 0 (KERN_EMERG) system is unusable
736 1 (KERN_ALERT) action must be taken immediately
737 2 (KERN_CRIT) critical conditions
738 3 (KERN_ERR) error conditions
739 4 (KERN_WARNING) warning conditions
740 5 (KERN_NOTICE) normal but significant condition
741 6 (KERN_INFO) informational
742 7 (KERN_DEBUG) debug-level messages
743
744 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
745 Format: { n | nk | nM }
746 n must be a power of two. The default size
747 is set in the kernel config file.
1da177e4
LT
748
749 lp=0 [LP] Specify parallel ports to use, e.g,
750 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
751 lp=reset first parallel port). 'lp=0' disables the
752 lp=auto printer driver. 'lp=reset' (which can be
753 specified in addition to the ports) causes
754 attached printers to be reset. Using
755 lp=port1,port2,... specifies the parallel ports
756 to associate lp devices with, starting with
757 lp0. A port specification may be 'none' to skip
758 that lp device, or a parport name such as
759 'parport0'. Specifying 'lp=auto' instead of a
760 port specification list means that device IDs
761 from each port should be examined, to see if
762 an IEEE 1284-compliant printer is attached; if
763 so, the driver will manage that printer.
764 See also header of drivers/char/lp.c.
765
766 lpj=n [KNL]
767 Sets loops_per_jiffy to given constant, thus avoiding
768 time-consuming boot-time autodetection (up to 250 ms per
769 CPU). 0 enables autodetection (default). To determine
770 the correct value for your kernel, boot with normal
771 autodetection and see what value is printed. Note that
772 on SMP systems the preset will be applied to all CPUs,
773 which is likely to cause problems if your CPUs need
774 significantly divergent settings. An incorrect value
775 will cause delays in the kernel to be wrong, leading to
776 unpredictable I/O errors and other breakage. Although
777 unlikely, in the extreme case this might damage your
778 hardware.
779
780 ltpc= [NET]
781 Format: <io>,<irq>,<dma>
782
a9913044
RD
783 mac5380= [HW,SCSI] Format:
784 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 785
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RD
786 mac53c9x= [HW,SCSI] Format:
787 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 788
a9913044
RD
789 machvec= [IA64] Force the use of a particular machine-vector
790 (machvec) in a generic kernel.
791 Example: machvec=hpzx1_swiotlb
1da177e4 792
a9913044
RD
793 mad16= [HW,OSS] Format:
794 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
795
796 maui= [HW,OSS]
797 Format: <io>,<irq>
a9913044
RD
798
799 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
800 be mounted
801 Format: <1-256>
802
803 maxcpus= [SMP] Maximum number of processors that an SMP kernel
804 should make use of
805
2b2c3750
BP
806 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
807 equal to this physical address is ignored.
808
a9913044 809 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
810 Should be between 1 and 2^32-1.
811
812 max_report_luns=
a9913044 813 [SCSI] Maximum number of LUNs received.
1da177e4
LT
814 Should be between 1 and 16384.
815
816 mca-pentium [BUGS=IA-32]
817
818 mcatest= [IA-64]
819
820 mcd= [HW,CD]
821 Format: <port>,<irq>,<mitsumi_bug_93_wait>
822
823 mcdx= [HW,CD]
824
825 mce [IA-32] Machine Check Exception
826
827 md= [HW] RAID subsystems devices and level
828 See Documentation/md.txt.
a9913044 829
1da177e4
LT
830 mdacon= [MDA]
831 Format: <first>,<last>
832 Specifies range of consoles to be captured by the MDA.
a9913044 833
1da177e4
LT
834 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
835 Amount of memory to be used when the kernel is not able
836 to see the whole system memory or for test.
837 [IA-32] Use together with memmap= to avoid physical
838 address space collisions. Without memmap= PCI devices
839 could be placed at addresses belonging to unused RAM.
840
841 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
842 memory.
843
69cda7b1 844 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
845 E820 memory map, as specified by the user.
846 Such memmap=exactmap lines can be constructed based on
847 BIOS output or other requirements. See the memmap=nn@ss
848 option description.
849
850 memmap=nn[KMG]@ss[KMG]
851 [KNL] Force usage of a specific region of memory
852 Region of memory to be used, from ss to ss+nn.
853
854 memmap=nn[KMG]#ss[KMG]
855 [KNL,ACPI] Mark specific memory as ACPI data.
856 Region of memory to be used, from ss to ss+nn.
857
858 memmap=nn[KMG]$ss[KMG]
859 [KNL,ACPI] Mark specific memory as reserved.
860 Region of memory to be used, from ss to ss+nn.
861
862 meye.*= [HW] Set MotionEye Camera parameters
863 See Documentation/video4linux/meye.txt.
864
865 mga= [HW,DRM]
866
198e2f18
AM
867 migration_cost=
868 [KNL,SMP] debug: override scheduler migration costs
869 Format: <level-1-usecs>,<level-2-usecs>,...
870 This debugging option can be used to override the
871 default scheduler migration cost matrix. The numbers
872 are indexed by 'CPU domain distance'.
873 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
874 box will set up an intra-core migration cost of
875 1 msec, an inter-core migration cost of 2 msecs,
876 and an inter-node migration cost of 3 msecs.
877
878 WARNING: using the wrong values here can break
879 scheduler performance, so it's only for scheduler
880 development purposes, not production environments.
881
882 migration_debug=
883 [KNL,SMP] migration cost auto-detect verbosity
884 Format=<0|1|2>
885 If a system's migration matrix reported at bootup
886 seems erroneous then this option can be used to
887 increase verbosity of the detection process.
888 We default to 0 (no extra messages), 1 will print
889 some more information, and 2 will be really
890 verbose (probably only useful if you also have a
891 serial console attached to the system).
892
893 migration_factor=
894 [KNL,SMP] multiply/divide migration costs by a factor
895 Format=<percent>
896 This debug option can be used to proportionally
897 increase or decrease the auto-detected migration
898 costs for all entries of the migration matrix.
899 E.g. migration_factor=150 will increase migration
900 costs by 50%. (and thus the scheduler will be less
901 eager migrating cache-hot tasks)
902 migration_factor=80 will decrease migration costs
903 by 20%. (thus the scheduler will be more eager to
904 migrate tasks)
905
906 WARNING: using the wrong values here can break
907 scheduler performance, so it's only for scheduler
908 development purposes, not production environments.
909
1da177e4
LT
910 mousedev.tap_time=
911 [MOUSE] Maximum time between finger touching and
912 leaving touchpad surface for touch to be considered
913 a tap and be reported as a left button click (for
914 touchpads working in absolute mode only).
915 Format: <msecs>
916 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
917 reporting absolute coordinates, such as tablets
918 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
919 reporting absolute coordinates, such as tablets
920
921 mpu401= [HW,OSS]
922 Format: <io>,<irq>
923
924 MTD_Partition= [MTD]
925 Format: <name>,<region-number>,<size>,<offset>
926
a9913044
RD
927 MTD_Region= [MTD] Format:
928 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
929
930 mtdparts= [MTD]
931 See drivers/mtd/cmdline.c.
932
933 mtouchusb.raw_coordinates=
a9913044
RD
934 [HW] Make the MicroTouch USB driver use raw coordinates
935 ('y', default) or cooked coordinates ('n')
1da177e4
LT
936
937 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
938
939 NCR_D700= [HW,SCSI]
940 See header of drivers/scsi/NCR_D700.c.
941
942 ncr5380= [HW,SCSI]
943
944 ncr53c400= [HW,SCSI]
945
946 ncr53c400a= [HW,SCSI]
947
948 ncr53c406a= [HW,SCSI]
949
950 ncr53c8xx= [HW,SCSI]
951
952 netdev= [NET] Network devices parameters
953 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
954 Note that mem_start is often overloaded to mean
955 something different and driver-specific.
a9913044
RD
956 This usage is only documented in each driver source
957 file if at all.
958
1da177e4
LT
959 nfsaddrs= [NFS]
960 See Documentation/nfsroot.txt.
961
962 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
963 See Documentation/nfsroot.txt.
964
a72b4422
TM
965 nfs.callback_tcpport=
966 [NFS] set the TCP port on which the NFSv4 callback
967 channel should listen.
968
58df095b
TM
969 nfs.idmap_cache_timeout=
970 [NFS] set the maximum lifetime for idmapper cache
971 entries.
972
1da177e4
LT
973 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
974
975 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
976 emulation library even if a 387 maths coprocessor
977 is present.
978
a9913044
RD
979 noalign [KNL,ARM]
980
1da177e4
LT
981 noapic [SMP,APIC] Tells the kernel to not make use of any
982 IOAPICs that may be present in the system.
983
984 noasync [HW,M68K] Disables async and sync negotiation for
985 all devices.
986
987 nobats [PPC] Do not use BATs for mapping kernel lowmem
988 on "Classic" PPC cores.
989
990 nocache [ARM]
a9913044 991
1da177e4
LT
992 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
993
994 noexec [IA-64]
995
a9913044 996 noexec [IA-32,X86-64]
1da177e4
LT
997 noexec=on: enable non-executable mappings (default)
998 noexec=off: disable nn-executable mappings
999
1000 nofxsr [BUGS=IA-32]
1001
1002 nohlt [BUGS=ARM]
a9913044 1003
1da177e4
LT
1004 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1005 instruction doesn't work correctly and not to
1006 use it.
1007
1008 nohalt [IA-64] Tells the kernel not to use the power saving
1009 function PAL_HALT_LIGHT when idle. This increases
1010 power-consumption. On the positive side, it reduces
1011 interrupt wake-up latency, which may improve performance
1012 in certain environments such as networked servers or
1013 real-time systems.
1014
1015 noirqdebug [IA-32] Disables the code which attempts to detect and
1016 disable unhandled interrupt sources.
1017
1018 noisapnp [ISAPNP] Disables ISA PnP code.
1019
1020 noinitrd [RAM] Tells the kernel not to load any configured
1021 initial RAM disk.
1022
1023 nointroute [IA-64]
1024
1025 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1026
1027 noltlbs [PPC] Do not use large page/tlb entries for kernel
1028 lowmem mapping on PPC40x.
1029
1030 nomce [IA-32] Machine Check Exception
1031
1032 noresidual [PPC] Don't use residual data on PReP machines.
1033
a9913044
RD
1034 noresume [SWSUSP] Disables resume and restores original swap
1035 space.
1036
1da177e4
LT
1037 no-scroll [VGA] Disables scrollback.
1038 This is required for the Braillex ib80-piezo Braille
1039 reader made by F.H. Papenmeier (Germany).
1040
1041 nosbagart [IA-64]
1042
1043 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1044
1045 nosync [HW,M68K] Disables sync negotiation for all devices.
1046
1047 notsc [BUGS=IA-32] Disable Time Stamp Counter
1048
1049 nousb [USB] Disable the USB subsystem
1050
1051 nowb [ARM]
a9913044 1052
a61c2d78
DJ
1053 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1054
1da177e4
LT
1055 opl3= [HW,OSS]
1056 Format: <io>
1057
1058 opl3sa= [HW,OSS]
1059 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1060
a9913044
RD
1061 opl3sa2= [HW,OSS] Format:
1062 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1063
1da177e4
LT
1064 oprofile.timer= [HW]
1065 Use timer interrupt instead of performance counters
1066
1067 optcd= [HW,CD]
1068 Format: <io>
1069
1070 osst= [HW,SCSI] SCSI Tape Driver
1071 Format: <buffer_size>,<write_threshold>
1072 See also Documentation/scsi/st.txt.
1073
1074 panic= [KNL] Kernel behaviour on panic
1075 Format: <timeout>
1076
1077 parkbd.port= [HW] Parallel port number the keyboard adapter is
1078 connected to, default is 0.
1079 Format: <parport#>
1080 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1081 0 for XT, 1 for AT (default is AT).
a9913044
RD
1082 Format: <mode>
1083
1084 parport= [HW,PPT] Specify parallel ports. 0 disables.
1085 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1086 Use 'auto' to force the driver to use any
1087 IRQ/DMA settings detected (the default is to
1088 ignore detected IRQ/DMA settings because of
1089 possible conflicts). You can specify the base
1090 address, IRQ, and DMA settings; IRQ and DMA
1091 should be numbers, or 'auto' (for using detected
1092 settings on that particular port), or 'nofifo'
1093 (to avoid using a FIFO even if it is detected).
1094 Parallel ports are assigned in the order they
1095 are specified on the command line, starting
1096 with parport0.
1097
1098 parport_init_mode= [HW,PPT]
1099 Configure VIA parallel port to operate in
1100 a specific mode. This is necessary on Pegasos
1101 computer where firmware has no options for setting
1102 up parallel port mode and sets it to spp.
1103 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1104 Format: [spp|ps2|epp|ecp|ecpepp]
1105
a9913044
RD
1106 pas2= [HW,OSS] Format:
1107 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1108
1da177e4
LT
1109 pas16= [HW,SCSI]
1110 See header of drivers/scsi/pas16.c.
1111
1112 pcbit= [HW,ISDN]
1113
1114 pcd. [PARIDE]
1115 See header of drivers/block/paride/pcd.c.
1116 See also Documentation/paride.txt.
1117
a9913044
RD
1118 pci=option[,option...] [PCI] various PCI subsystem options:
1119 off [IA-32] don't probe for the PCI bus
1120 bios [IA-32] force use of PCI BIOS, don't access
1121 the hardware directly. Use this if your machine
1122 has a non-standard PCI host bridge.
1123 nobios [IA-32] disallow use of PCI BIOS, only direct
1124 hardware access methods are allowed. Use this
1125 if you experience crashes upon bootup and you
1126 suspect they are caused by the BIOS.
1127 conf1 [IA-32] Force use of PCI Configuration
1128 Mechanism 1.
1129 conf2 [IA-32] Force use of PCI Configuration
1130 Mechanism 2.
1131 nosort [IA-32] Don't sort PCI devices according to
1132 order given by the PCI BIOS. This sorting is
1133 done to get a device order compatible with
1134 older kernels.
1135 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1136 routing table. These calls are known to be buggy
1137 on several machines and they hang the machine
1138 when used, but on other computers it's the only
1139 way to get the interrupt routing table. Try
1140 this option if the kernel is unable to allocate
1141 IRQs or discover secondary PCI buses on your
1142 motherboard.
1143 rom [IA-32] Assign address space to expansion ROMs.
1144 Use with caution as certain devices share
1145 address decoders between ROMs and other
1146 resources.
1147 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1148 assigned automatically to PCI devices. You can
1149 make the kernel exclude IRQs of your ISA cards
1150 this way.
120bb424 1151 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1152 of the PIRQ table (normally generated
1153 by the BIOS) if it is outside the
1154 F0000h-100000h range.
1155 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1156 useful if the kernel is unable to find your
1157 secondary buses and you want to tell it
1158 explicitly which ones they are.
1159 assign-busses [IA-32] Always assign all PCI bus
1160 numbers ourselves, overriding
1161 whatever the firmware may have done.
1162 usepirqmask [IA-32] Honor the possible IRQ mask stored
1163 in the BIOS $PIR table. This is needed on
1164 some systems with broken BIOSes, notably
1165 some HP Pavilion N5400 and Omnibook XE3
1166 notebooks. This will have no effect if ACPI
1167 IRQ routing is enabled.
1168 noacpi [IA-32] Do not use ACPI for IRQ routing
1169 or for PCI scanning.
1170 routeirq Do IRQ routing for all PCI devices.
1171 This is normally done in pci_enable_device(),
1172 so this option is a temporary workaround
1173 for broken drivers that don't call it.
1174 firmware [ARM] Do not re-enumerate the bus but instead
1175 just use the configuration from the
1176 bootloader. This is currently used on
1177 IXP2000 systems where the bus has to be
1178 configured a certain way for adjunct CPUs.
1da177e4
LT
1179
1180 pcmv= [HW,PCMCIA] BadgePAD 4
1181
1182 pd. [PARIDE]
1183 See Documentation/paride.txt.
1184
1185 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1186 boot time.
1187 Format: { 0 | 1 }
1188 See arch/parisc/kernel/pdc_chassis.c
1189
1190 pf. [PARIDE]
1191 See Documentation/paride.txt.
1192
1193 pg. [PARIDE]
1194 See Documentation/paride.txt.
1195
1196 pirq= [SMP,APIC] Manual mp-table setup
1197 See Documentation/i386/IO-APIC.txt.
1198
1199 plip= [PPT,NET] Parallel port network link
1200 Format: { parport<nr> | timid | 0 }
1201 See also Documentation/parport.txt.
1202
1203 pnpacpi= [ACPI]
1204 { off }
1205
1206 pnpbios= [ISAPNP]
1207 { on | off | curr | res | no-curr | no-res }
1208
1209 pnp_reserve_irq=
1210 [ISAPNP] Exclude IRQs for the autoconfiguration
1211
1212 pnp_reserve_dma=
1213 [ISAPNP] Exclude DMAs for the autoconfiguration
1214
1215 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1216 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1217
1218 pnp_reserve_mem=
a9913044
RD
1219 [ISAPNP] Exclude memory regions for the
1220 autoconfiguration.
1da177e4
LT
1221 Ranges are in pairs (memory base and size).
1222
1223 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1224 Format: [schedule,]<number>
1225 Param: "schedule" - profile schedule points.
1226 Param: <number> - step/bucket size as a power of 2 for
1227 statistical time based profiling.
1da177e4 1228
a9913044 1229 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1230 Limit processor to maximum C-state
1231 max_cstate=9 overrides any DMI blacklist limit.
1232
41c0d868
LB
1233 processor.nocst [HW,ACPI]
1234 Ignore the _CST method to determine C-states,
1235 instead using the legacy FADT method
1236
1da177e4
LT
1237 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1238 before loading.
1239 See Documentation/ramdisk.txt.
1240
a9913044
RD
1241 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1242 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1243 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1244 per second.
a9913044
RD
1245 psmouse.resetafter= [HW,MOUSE]
1246 Try to reset the device after so many bad packets
1da177e4
LT
1247 (0 = never).
1248 psmouse.resolution=
1249 [HW,MOUSE] Set desired mouse resolution, in dpi.
1250 psmouse.smartscroll=
a9913044 1251 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1252 0 = disabled, 1 = enabled (default).
1253
1254 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1255 Format:
1256 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1257
1258 pt. [PARIDE]
1259 See Documentation/paride.txt.
1260
1261 quiet= [KNL] Disable log messages
a9913044 1262
1da177e4
LT
1263 r128= [HW,DRM]
1264
1265 raid= [HW,RAID]
1266 See Documentation/md.txt.
1267
1268 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1269 See Documentation/ramdisk.txt.
1270
a9913044 1271 ramdisk_blocksize= [RAM]
1da177e4 1272 See Documentation/ramdisk.txt.
a9913044 1273
1da177e4
LT
1274 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1275 New name for the ramdisk parameter.
1276 See Documentation/ramdisk.txt.
1277
ffdfc409
OJ
1278 rdinit= [KNL]
1279 Format: <full_path>
1280 Run specified binary instead of /init from the ramdisk,
1281 used for early userspace startup. See initrd.
1282
1da177e4
LT
1283 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1284 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1285 See arch/*/kernel/reboot.c.
1286
1287 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1288
a9913044
RD
1289 resume= [SWSUSP]
1290 Specify the partition device for software suspend
1da177e4
LT
1291
1292 rhash_entries= [KNL,NET]
1293 Set number of hash buckets for route cache
1294
1295 riscom8= [HW,SERIAL]
1296 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1297
1298 ro [KNL] Mount root device read-only on boot
1299
1300 root= [KNL] Root filesystem
1301
1302 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1303 mount the root filesystem
1304
1305 rootflags= [KNL] Set root filesystem mount option string
1306
1307 rootfstype= [KNL] Set root filesystem type
1308
1309 rw [KNL] Mount root device read-write on boot
1310
1311 S [KNL] Run init in single mode
1312
1313 sa1100ir [NET]
1314 See drivers/net/irda/sa1100_ir.c.
1315
1316 sb= [HW,OSS]
1317 Format: <io>,<irq>,<dma>,<dma2>
1318
1319 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1320
1da177e4
LT
1321 sbpcd= [HW,CD] Soundblaster CD adapter
1322 Format: <io>,<type>
1323 See a comment before function sbpcd_setup() in
1324 drivers/cdrom/sbpcd.c.
1325
1326 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1327 Format: <io>[,<timeout>[,<isapnp>]]
1328
1329 scsi_debug_*= [SCSI]
1330 See drivers/scsi/scsi_debug.c.
1331
1332 scsi_default_dev_flags=
1333 [SCSI] SCSI default device flags
1334 Format: <integer>
1335
1336 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1337 Format: <vendor>:<model>:<flags>
1338 (flags are integer value)
1339
1340 scsi_logging= [SCSI]
1341
1342 selinux [SELINUX] Disable or enable SELinux at boot time.
1343 Format: { "0" | "1" }
1344 See security/selinux/Kconfig help text.
1345 0 -- disable.
1346 1 -- enable.
1347 Default value is set via kernel config option.
1348 If enabled at boot time, /selinux/disable can be used
1349 later to disable prior to initial policy load.
1350
1351 serialnumber [BUGS=IA-32]
1352
a9913044
RD
1353 sg_def_reserved_size= [SCSI]
1354
1da177e4
LT
1355 sgalaxy= [HW,OSS]
1356 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1357
1358 shapers= [NET]
1359 Maximal number of shapers.
a9913044 1360
1da177e4
LT
1361 sim710= [SCSI,HW]
1362 See header of drivers/scsi/sim710.c.
1363
1364 simeth= [IA-64]
1365 simscsi=
a9913044 1366
1da177e4
LT
1367 sjcd= [HW,CD]
1368 Format: <io>,<irq>,<dma>
1369 See header of drivers/cdrom/sjcd.c.
1370
1371 slram= [HW,MTD]
1372
1373 smart2= [HW]
1374 Format: <io1>[,<io2>[,...,<io8>]]
1375
1376 snd-ad1816a= [HW,ALSA]
1377
1378 snd-ad1848= [HW,ALSA]
1379
1380 snd-ali5451= [HW,ALSA]
1381
1382 snd-als100= [HW,ALSA]
1383
1384 snd-als4000= [HW,ALSA]
1385
1386 snd-azt2320= [HW,ALSA]
1387
1388 snd-cmi8330= [HW,ALSA]
1389
1390 snd-cmipci= [HW,ALSA]
1391
1392 snd-cs4231= [HW,ALSA]
1393
1394 snd-cs4232= [HW,ALSA]
1395
1396 snd-cs4236= [HW,ALSA]
1397
1398 snd-cs4281= [HW,ALSA]
1399
1400 snd-cs46xx= [HW,ALSA]
1401
1402 snd-dt019x= [HW,ALSA]
1403
1404 snd-dummy= [HW,ALSA]
1405
1406 snd-emu10k1= [HW,ALSA]
1407
1408 snd-ens1370= [HW,ALSA]
1409
1410 snd-ens1371= [HW,ALSA]
1411
1412 snd-es968= [HW,ALSA]
1413
1414 snd-es1688= [HW,ALSA]
1415
1416 snd-es18xx= [HW,ALSA]
1417
1418 snd-es1938= [HW,ALSA]
1419
1420 snd-es1968= [HW,ALSA]
1421
1422 snd-fm801= [HW,ALSA]
1423
1424 snd-gusclassic= [HW,ALSA]
1425
1426 snd-gusextreme= [HW,ALSA]
1427
1428 snd-gusmax= [HW,ALSA]
1429
1430 snd-hdsp= [HW,ALSA]
1431
1432 snd-ice1712= [HW,ALSA]
1433
1434 snd-intel8x0= [HW,ALSA]
1435
1436 snd-interwave= [HW,ALSA]
1437
1438 snd-interwave-stb=
1439 [HW,ALSA]
1440
1441 snd-korg1212= [HW,ALSA]
1442
1443 snd-maestro3= [HW,ALSA]
1444
1445 snd-mpu401= [HW,ALSA]
1446
1447 snd-mtpav= [HW,ALSA]
1448
1449 snd-nm256= [HW,ALSA]
1450
1451 snd-opl3sa2= [HW,ALSA]
1452
1453 snd-opti92x-ad1848=
1454 [HW,ALSA]
1455
1456 snd-opti92x-cs4231=
1457 [HW,ALSA]
1458
1459 snd-opti93x= [HW,ALSA]
1460
1461 snd-pmac= [HW,ALSA]
1462
1463 snd-rme32= [HW,ALSA]
1464
1465 snd-rme96= [HW,ALSA]
1466
1467 snd-rme9652= [HW,ALSA]
1468
1469 snd-sb8= [HW,ALSA]
1470
1471 snd-sb16= [HW,ALSA]
1472
1473 snd-sbawe= [HW,ALSA]
1474
1475 snd-serial= [HW,ALSA]
1476
1477 snd-sgalaxy= [HW,ALSA]
1478
1479 snd-sonicvibes= [HW,ALSA]
1480
1481 snd-sun-amd7930=
1482 [HW,ALSA]
1483
1484 snd-sun-cs4231= [HW,ALSA]
1485
1486 snd-trident= [HW,ALSA]
1487
1488 snd-usb-audio= [HW,ALSA,USB]
1489
1490 snd-via82xx= [HW,ALSA]
1491
1492 snd-virmidi= [HW,ALSA]
1493
1494 snd-wavefront= [HW,ALSA]
1495
1496 snd-ymfpci= [HW,ALSA]
a9913044 1497
1da177e4
LT
1498 sonicvibes= [HW,OSS]
1499 Format: <reverb>
a9913044 1500
1da177e4
LT
1501 sonycd535= [HW,CD]
1502 Format: <io>[,<irq>]
1503
1504 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1505 See Documentation/sonypi.txt
1506
1507 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1508 See Documentation/specialix.txt.
1509
1510 spia_io_base= [HW,MTD]
1511 spia_fio_base=
1512 spia_pedr=
1513 spia_peddr=
1514
1515 sscape= [HW,OSS]
1516 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1517
1da177e4
LT
1518 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1519 See Documentation/scsi/st.txt.
1520
1521 st0x= [HW,SCSI]
1522 See header of drivers/scsi/seagate.c.
1523
1524 sti= [PARISC,HW]
1525 Format: <num>
1526 Set the STI (builtin display/keyboard on the HP-PARISC
1527 machines) console (graphic card) which should be used
1528 as the initial boot-console.
1529 See also comment in drivers/video/console/sticore.c.
1530
1531 sti_font= [HW]
1532 See comment in drivers/video/console/sticore.c.
1533
1534 stifb= [HW]
1535 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1536
1da177e4 1537 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1538
1da177e4
LT
1539 switches= [HW,M68k]
1540
1541 sym53c416= [HW,SCSI]
1542 See header of drivers/scsi/sym53c416.c.
1543
1544 t128= [HW,SCSI]
1545 See header of drivers/scsi/t128.c.
1546
1547 tdfx= [HW,DRM]
1548
1549 thash_entries= [KNL,NET]
1550 Set number of hash buckets for TCP connection
1551
1552 time Show timing data prefixed to each printk message line
1553
1554 tipar.timeout= [HW,PPT]
1555 Set communications timeout in tenths of a second
1556 (default 15).
1557
1558 tipar.delay= [HW,PPT]
1559 Set inter-bit delay in microseconds (default 10).
1560
1561 tmc8xx= [HW,SCSI]
1562 See header of drivers/scsi/seagate.c.
1563
1564 tmscsim= [HW,SCSI]
1565 See comment before function dc390_setup() in
1566 drivers/scsi/tmscsim.c.
1567
1568 tp720= [HW,PS2]
1569
1570 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1571 Format:
1572 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1573
1da177e4
LT
1574 tsdev.xres= [TS] Horizontal screen resolution.
1575 tsdev.yres= [TS] Vertical screen resolution.
1576
a9913044
RD
1577 turbografx.map[2|3]= [HW,JOY]
1578 TurboGraFX parallel port interface
1579 Format:
1580 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1581 See also Documentation/input/joystick-parport.txt
1582
1583 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1584 See header of drivers/scsi/u14-34f.c.
1585
1586 uart401= [HW,OSS]
1587 Format: <io>,<irq>
1588
1589 uart6850= [HW,OSS]
1590 Format: <io>,<irq>
1591
1da177e4
LT
1592 usbhid.mousepoll=
1593 [USBHID] The interval which mice are to be polled at.
a9913044 1594
1da177e4
LT
1595 video= [FB] Frame buffer configuration
1596 See Documentation/fb/modedb.txt.
1597
1598 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1599 See Documentation/i386/boot.txt and
1600 Documentation/svga.txt.
1da177e4
LT
1601 Use vga=ask for menu.
1602 This is actually a boot loader parameter; the value is
1603 passed to the kernel using a special protocol.
1604
a9913044 1605 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1606 size of <nn>. This can be used to increase the
1607 minimum size (128MB on x86). It can also be used to
1608 decrease the size and leave more room for directly
1609 mapped kernel RAM.
1610
1611 vmhalt= [KNL,S390]
1612
a9913044
RD
1613 vmpoff= [KNL,S390]
1614
1da177e4
LT
1615 waveartist= [HW,OSS]
1616 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1617
1da177e4
LT
1618 wd33c93= [HW,SCSI]
1619 See header of drivers/scsi/wd33c93.c.
1620
1621 wd7000= [HW,SCSI]
1622 See header of drivers/scsi/wd7000.c.
1623
1624 wdt= [WDT] Watchdog
1625 See Documentation/watchdog/watchdog.txt.
1626
1627 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1628 xd_geo= See header of drivers/block/xd.c.
1629
1630 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1631 Format:
1632 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4
LT
1633
1634
a9913044 1635______________________________________________________________________
1da177e4
LT
1636Changelog:
1637
a9913044 16382000-06-?? Mr. Unknown
1da177e4 1639 The last known update (for 2.4.0) - the changelog was not kept before.
1da177e4 1640
a9913044
RD
16412002-11-24 Petr Baudis <pasky@ucw.cz>
1642 Randy Dunlap <randy.dunlap@verizon.net>
1da177e4
LT
1643 Update for 2.5.49, description for most of the options introduced,
1644 references to other documentation (C files, READMEs, ..), added S390,
1645 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1646 reformatting.
a9913044
RD
1647
16482005-10-19 Randy Dunlap <rdunlap@xenotime.net>
1649 Lots of typos, whitespace, some reformatting.
1da177e4
LT
1650
1651TODO:
1652
1653 Add documentation for ALSA options.
1654 Add more DRM drivers.