[PATCH] Time: i386 Conversion - part 4: Remove Old timer_opts Code
[linux-2.6-block.git] / Documentation / kernel-parameters.txt
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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 enable_timer_pin_1 [i386,x86-64]
184 Enable PIN 1 of APIC timer
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185 Can be useful to work around chipset bugs
186 (in particular on some ATI chipsets).
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187 The kernel tries to set a reasonable default.
188
189 disable_timer_pin_1 [i386,x86-64]
190 Disable PIN 1 of APIC timer
191 Can be useful to work around chipset bugs.
192
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193 ad1816= [HW,OSS]
194 Format: <io>,<irq>,<dma>,<dma2>
195 See also Documentation/sound/oss/AD1816.
196
197 ad1848= [HW,OSS]
198 Format: <io>,<irq>,<dma>,<dma2>,<type>
199
200 adlib= [HW,OSS]
201 Format: <io>
a9913044 202
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203 advansys= [HW,SCSI]
204 See header of drivers/scsi/advansys.c.
205
206 advwdt= [HW,WDT] Advantech WDT
207 Format: <iostart>,<iostop>
208
209 aedsp16= [HW,OSS] Audio Excel DSP 16
210 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
211 See also header of sound/oss/aedsp16.c.
a9913044 212
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213 aha152x= [HW,SCSI]
214 See Documentation/scsi/aha152x.txt.
215
216 aha1542= [HW,SCSI]
217 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
218
219 aic7xxx= [HW,SCSI]
220 See Documentation/scsi/aic7xxx.txt.
221
222 aic79xx= [HW,SCSI]
223 See Documentation/scsi/aic79xx.txt.
224
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225 amijoy.map= [HW,JOY] Amiga joystick support
226 Map of devices attached to JOY0DAT and JOY1DAT
227 Format: <a>,<b>
228 See also Documentation/kernel/input/joystick.txt
229
230 analog.map= [HW,JOY] Analog joystick and gamepad support
231 Specifies type or capabilities of an analog joystick
232 connected to one of 16 gameports
233 Format: <type1>,<type2>,..<type16>
234
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235 apc= [HW,SPARC]
236 Power management functions (SPARCstation-4/5 + deriv.)
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237 Format: noidle
238 Disable APC CPU standby support. SPARCstation-Fox does
239 not play well with APC CPU idle - disable it if you have
240 APC and your system crashes randomly.
241
a9913044 242 apic= [APIC,i386] Change the output verbosity whilst booting
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243 Format: { quiet (default) | verbose | debug }
244 Change the amount of debugging information output
245 when initialising the APIC and IO-APIC components.
a9913044 246
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247 apm= [APM] Advanced Power Management
248 See header of arch/i386/kernel/apm.c.
249
250 applicom= [HW]
251 Format: <mem>,<irq>
a9913044 252
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253 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
254 Format: <io>,<irq>,<nodeID>
255
256 ataflop= [HW,M68k]
257
258 atarimouse= [HW,MOUSE] Atari Mouse
259
260 atascsi= [HW,SCSI] Atari SCSI
261
262 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
263 EzKey and similar keyboards
264
265 atkbd.reset= [HW] Reset keyboard during initialization
266
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267 atkbd.set= [HW] Select keyboard code set
268 Format: <int> (2 = AT (default), 3 = PS/2)
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269
270 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
271 keyboards
272
273 atkbd.softraw= [HW] Choose between synthetic and real raw mode
274 Format: <bool> (0 = real, 1 = synthetic (default))
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275
276 atkbd.softrepeat= [HW]
277 Use software keyboard repeat
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278
279 autotest [IA64]
280
281 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
282 Format: <io>,<memsize>,<isapnp>
a9913044 283
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284 aztcd= [HW,CD] Aztech CD268 CDROM driver
285 Format: <io>,0x79 (?)
286
287 baycom_epp= [HW,AX25]
288 Format: <io>,<mode>
a9913044 289
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290 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
291 Format: <io>,<mode>
292 See header of drivers/net/hamradio/baycom_par.c.
293
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294 baycom_ser_fdx= [HW,AX25]
295 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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296 Format: <io>,<irq>,<mode>[,<baud>]
297 See header of drivers/net/hamradio/baycom_ser_fdx.c.
298
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299 baycom_ser_hdx= [HW,AX25]
300 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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301 Format: <io>,<irq>,<mode>
302 See header of drivers/net/hamradio/baycom_ser_hdx.c.
303
304 blkmtd_device= [HW,MTD]
305 blkmtd_erasesz=
306 blkmtd_ro=
307 blkmtd_bs=
308 blkmtd_count=
309
310 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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311 bttv.radio= Most important insmod options are available as
312 kernel args too.
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313 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
314 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
315
316 BusLogic= [HW,SCSI]
317 See drivers/scsi/BusLogic.c, comment before function
318 BusLogic_ParseDriverOptions().
319
320 c101= [NET] Moxa C101 synchronous serial card
321
322 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
323 Sometimes CPU hardware bugs make them report the cache
324 size incorrectly. The kernel will attempt work arounds
325 to fix known problems, but for some CPUs it is not
326 possible to determine what the correct size should be.
327 This option provides an override for these situations.
328
329 cdu31a= [HW,CD]
330 Format: <io>,<irq>[,PAS]
331 See header of drivers/cdrom/cdu31a.c.
332
333 chandev= [HW,NET] Generic channel device initialisation
334
335 checkreqprot [SELINUX] Set initial checkreqprot flag value.
336 Format: { "0" | "1" }
337 See security/selinux/Kconfig help text.
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338 0 -- check protection applied by kernel (includes
339 any implied execute protection).
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340 1 -- check protection requested by application.
341 Default value is set via a kernel config option.
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342 Value can be changed at runtime via
343 /selinux/checkreqprot.
344
734efb46 345 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
346 [Deprecated]
347 Forces specified clocksource (if avaliable) to be used
348 when calculating gettimeofday(). If specified
349 clocksource is not avalible, it defaults to PIT.
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350 Format: { pit | tsc | cyclone | pmtmr }
351
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352 disable_8254_timer
353 enable_8254_timer
354 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
355 over the 8254 in addition to over the IO-APIC. The
356 kernel tries to set a sensible default.
357
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358 hpet= [IA-32,HPET] option to disable HPET and use PIT.
359 Format: disable
360
361 cm206= [HW,CD]
362 Format: { auto | [<io>,][<irq>] }
363
364 com20020= [HW,NET] ARCnet - COM20020 chipset
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365 Format:
366 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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367
368 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
369 Format: <io>[,<irq>]
370
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371 com90xx= [HW,NET]
372 ARCnet - COM90xx chipset (memory-mapped buffers)
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373 Format: <io>[,<irq>[,<memstart>]]
374
375 condev= [HW,S390] console device
376 conmode=
a9913044 377
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378 console= [KNL] Output console device and options.
379
380 tty<n> Use the virtual console device <n>.
381
382 ttyS<n>[,options]
f1a1c2dc 383 ttyUSB0[,options]
1da177e4 384 Use the specified serial port. The options are of
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385 the form "bbbbpnf", where "bbbb" is the baud rate,
386 "p" is parity ("n", "o", or "e"), "n" is number of
387 bits, and "f" is flow control ("r" for RTS or
388 omit it). Default is "9600n8".
389
390 See Documentation/serial-console.txt for more
391 information. See
392 Documentation/networking/netconsole.txt for an
393 alternative.
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394
395 uart,io,<addr>[,options]
396 uart,mmio,<addr>[,options]
397 Start an early, polled-mode console on the 8250/16550
398 UART at the specified I/O port or MMIO address,
399 switching to the matching ttyS device later. The
400 options are the same as for ttyS, above.
401
402 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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403 Format:
404 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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405
406 cpia_pp= [HW,PPT]
407 Format: { parport<nr> | auto | none }
408
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409 crashkernel=nn[KMG]@ss[KMG]
410 [KNL] Reserve a chunk of physical memory to
411 hold a kernel to switch to with kexec on panic.
412
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413 cs4232= [HW,OSS]
414 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
415
416 cs89x0_dma= [HW,NET]
417 Format: <dma>
418
419 cs89x0_media= [HW,NET]
420 Format: { rj45 | aui | bnc }
a9913044 421
1da177e4 422 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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423
424 dasd= [HW,NET]
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425 See header of drivers/s390/block/dasd_devmap.c.
426
427 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
428 (one device per port)
429 Format: <port#>,<type>
430 See also Documentation/input/joystick-parport.txt
431
432 debug [KNL] Enable kernel debugging (events log level).
433
434 decnet= [HW,NET]
435 Format: <area>[,<node>]
436 See also Documentation/networking/decnet.txt.
437
438 devfs= [DEVFS]
439 See Documentation/filesystems/devfs/boot-options.
440
441 dhash_entries= [KNL]
442 Set number of hash buckets for dentry cache.
a9913044 443
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444 digi= [HW,SERIAL]
445 IO parameters + enable/disable command.
446
447 digiepca= [HW,SERIAL]
448 See drivers/char/README.epca and
449 Documentation/digiepca.txt.
450
451 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
452 support available.
453 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
454
455 dmasound= [HW,OSS] Sound subsystem buffers
456
457 dscc4.setup= [NET]
458
459 dtc3181e= [HW,SCSI]
460
a9913044 461 earlyprintk= [IA-32,X86-64]
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462 earlyprintk=vga
463 earlyprintk=serial[,ttySn[,baudrate]]
464
a9913044 465 Append ",keep" to not disable it when the real console
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466 takes over.
467
468 Only vga or serial at a time, not both.
469
470 Currently only ttyS0 and ttyS1 are supported.
471
472 Interaction with the standard serial driver is not
473 very good.
474
475 The VGA output is eventually overwritten by the real
476 console.
477
478 eata= [HW,SCSI]
479
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480 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
481 Format: <int>
482 0: polling mode
483 non-0: interrupt mode (default)
484
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485 eda= [HW,PS2]
486
487 edb= [HW,PS2]
488
489 edd= [EDD]
490 Format: {"of[f]" | "sk[ipmbr]"}
491 See comment in arch/i386/boot/edd.S
492
a9913044 493 eicon= [HW,ISDN]
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494 Format: <id>,<membase>,<irq>
495
496 eisa_irq_edge= [PARISC,HW]
497 See header of drivers/parisc/eisa.c.
498
499 elanfreq= [IA-32]
500 See comment before function elanfreq_setup() in
501 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
502
503 elevator= [IOSCHED]
16ab3adf 504 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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505 See Documentation/block/as-iosched.txt and
506 Documentation/block/deadline-iosched.txt for details.
507
aac04b32 508 elfcorehdr= [IA-32, X86_64]
a9913044 509 Specifies physical address of start of kernel core
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510 image elf header. Generally kexec loader will
511 pass this option to capture kernel.
512 See Documentation/kdump/kdump.txt for details.
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513
514 enforcing [SELINUX] Set initial enforcing status.
515 Format: {"0" | "1"}
516 See security/selinux/Kconfig help text.
517 0 -- permissive (log only, no denials).
518 1 -- enforcing (deny and log).
519 Default value is 0.
520 Value can be changed at runtime via /selinux/enforce.
521
522 es1370= [HW,OSS]
523 Format: <lineout>[,<micbias>]
524 See also header of sound/oss/es1370.c.
525
526 es1371= [HW,OSS]
527 Format: <spdif>,[<nomix>,[<amplifier>]]
528 See also header of sound/oss/es1371.c.
a9913044 529
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530 ether= [HW,NET] Ethernet cards parameters
531 This option is obsoleted by the "netdev=" option, which
532 has equivalent usage. See its documentation for details.
533
534 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
535 Format: <io>[,<irq>]
536
537 fd_mcs= [HW,SCSI]
538 See header of drivers/scsi/fd_mcs.c.
539
540 fdomain= [HW,SCSI]
541 See header of drivers/scsi/fdomain.c.
542
543 floppy= [HW]
544 See Documentation/floppy.txt.
545
546 ftape= [HW] Floppy Tape subsystem debugging options.
547 See Documentation/ftape.txt.
548
549 gamecon.map[2|3]=
550 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
551 support via parallel port (up to 5 devices per port)
552 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
553 See also Documentation/input/joystick-parport.txt
554
555 gamma= [HW,DRM]
556
557 gdth= [HW,SCSI]
558 See header of drivers/scsi/gdth.c.
559
560 gpt [EFI] Forces disk with valid GPT signature but
561 invalid Protective MBR to be treated as GPT.
562
563 gscd= [HW,CD]
564 Format: <io>
565
566 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
567
568 gus= [HW,OSS]
569 Format: <io>,<irq>,<dma>,<dma16>
a9913044 570
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571 gvp11= [HW,SCSI]
572
573 hashdist= [KNL,NUMA] Large hashes allocated during boot
574 are distributed across NUMA nodes. Defaults on
575 for IA-64, off otherwise.
a9913044 576 Format: 0 | 1 (for off | on)
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577
578 hcl= [IA-64] SGI's Hardware Graph compatibility layer
579
580 hd= [EIDE] (E)IDE hard drive subsystem geometry
581 Format: <cyl>,<head>,<sect>
582
583 hd?= [HW] (E)IDE subsystem
584 hd?lun= See Documentation/ide.txt.
585
586 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
587 size of <nn>. This works even on boxes that have no
588 highmem otherwise. This also works to reduce highmem
589 size on bigger boxes.
590
591 hisax= [HW,ISDN]
592 See Documentation/isdn/README.HiSax.
593
594 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
595
596 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
597
598 i8042.direct [HW] Put keyboard port into non-translated mode
599 i8042.dumbkbd [HW] Pretend that controlled can only read data from
600 keyboard and can not control its state
601 (Don't attempt to blink the leds)
602 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 603 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
604 i8042.nomux [HW] Don't check presence of an active multiplexing
605 controller
606 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
607 controllers
608 i8042.panicblink=
609 [HW] Frequency with which keyboard LEDs should blink
610 when kernel panics (default is 0.5 sec)
611 i8042.reset [HW] Reset the controller during init and cleanup
612 i8042.unlock [HW] Unlock (ignore) the keylock
613
614 i810= [HW,DRM]
615
e70c9d5e
DT
616 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
617 indicates that the driver is running on unsupported
618 hardware.
1da177e4
LT
619 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
620 does not match list of supported models.
621 i8k.power_status
622 [HW] Report power status in /proc/i8k
623 (disabled by default)
624 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
625 capability is set.
626
627 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
628 See Documentation/mca.txt.
629
630 icn= [HW,ISDN]
631 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
632
633 ide= [HW] (E)IDE subsystem
634 Format: ide=nodma or ide=doubler or ide=reverse
635 See Documentation/ide.txt.
636
637 ide?= [HW] (E)IDE subsystem
638 Format: ide?=noprobe or chipset specific parameters.
639 See Documentation/ide.txt.
a9913044 640
1da177e4
LT
641 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
642 See Documentation/ide.txt.
643
644 idle= [HW]
645 Format: idle=poll or idle=halt
a9913044 646
1da177e4
LT
647 ihash_entries= [KNL]
648 Set number of hash buckets for inode cache.
649
650 in2000= [HW,SCSI]
651 See header of drivers/scsi/in2000.c.
652
653 init= [KNL]
654 Format: <full_path>
655 Run specified binary instead of /sbin/init as init
656 process.
657
658 initcall_debug [KNL] Trace initcalls as they are executed. Useful
659 for working out where the kernel is dying during
660 startup.
661
662 initrd= [BOOT] Specify the location of the initial ramdisk
663
664 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
665 Format: <irq>
666
2bd0fa3b
JB
667 combined_mode= [HW] control which driver uses IDE ports in combined
668 mode: legacy IDE driver, libata, or both
669 (in the libata case, libata.atapi_enabled=1 may be
670 useful as well). Note that using the ide or libata
671 options may affect your device naming (e.g. by
672 changing hdc to sdb).
673 Format: combined (default), ide, or libata
674
1da177e4
LT
675 inttest= [IA64]
676
677 io7= [HW] IO7 for Marvel based alpha systems
678 See comment before marvel_specify_io7 in
679 arch/alpha/kernel/core_marvel.c.
680
681 ip= [IP_PNP]
682 See Documentation/nfsroot.txt.
683
684 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
685 See comment before ip2_setup() in drivers/char/ip2.c.
686
687 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
688 See header of drivers/scsi/ips.c.
689
200803df
AC
690 irqfixup [HW]
691 When an interrupt is not handled search all handlers
692 for it. Intended to get systems with badly broken
693 firmware running.
694
695 irqpoll [HW]
696 When an interrupt is not handled search all handlers
697 for it. Also check all handlers each timer
698 interrupt. Intended to get systems with badly broken
699 firmware running.
700
1da177e4 701 isapnp= [ISAPNP]
a9913044 702 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
703
704 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
705 Format: <cpu number>,...,<cpu number>
706 This option can be used to specify one or more CPUs
707 to isolate from the general SMP balancing and scheduling
708 algorithms. The only way to move a process onto or off
709 an "isolated" CPU is via the CPU affinity syscalls.
710 <cpu number> begins at 0 and the maximum value is
711 "number of CPUs in system - 1".
712
713 This option is the preferred way to isolate CPUs. The
a9913044
RD
714 alternative -- manually setting the CPU mask of all
715 tasks in the system -- can cause problems and
716 suboptimal load balancer performance.
1da177e4
LT
717
718 isp16= [HW,CD]
719 Format: <io>,<irq>,<dma>,<setup>
720
a9913044 721 iucv= [HW,NET]
1da177e4
LT
722
723 js= [HW,JOY] Analog joystick
724 See Documentation/input/joystick.txt.
725
726 keepinitrd [HW,ARM]
727
a9913044 728 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
729 in oops dumps.
730
731 l2cr= [PPC]
732
a9913044
RD
733 lapic [IA-32,APIC] Enable the local APIC even if BIOS
734 disabled it.
1da177e4
LT
735
736 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
737 Format: addr:<io>,irq:<irq>
738
a9913044
RD
739 llsc*= [IA64] See function print_params() in
740 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
741
742 load_ramdisk= [RAM] List of ramdisks to load from floppy
743 See Documentation/ramdisk.txt.
744
a6b25b67
RD
745 lockd.nlm_grace_period=P [NFS] Assign grace period.
746 Format: <integer>
1da177e4 747
a6b25b67
RD
748 lockd.nlm_tcpport=N [NFS] Assign TCP port.
749 Format: <integer>
750
751 lockd.nlm_timeout=T [NFS] Assign timeout value.
752 Format: <integer>
753
754 lockd.nlm_udpport=M [NFS] Assign UDP port.
755 Format: <integer>
1da177e4
LT
756
757 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
758 Format: <irq>
759
760 loglevel= All Kernel Messages with a loglevel smaller than the
761 console loglevel will be printed to the console. It can
762 also be changed with klogd or other programs. The
763 loglevels are defined as follows:
764
765 0 (KERN_EMERG) system is unusable
766 1 (KERN_ALERT) action must be taken immediately
767 2 (KERN_CRIT) critical conditions
768 3 (KERN_ERR) error conditions
769 4 (KERN_WARNING) warning conditions
770 5 (KERN_NOTICE) normal but significant condition
771 6 (KERN_INFO) informational
772 7 (KERN_DEBUG) debug-level messages
773
774 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
775 Format: { n | nk | nM }
776 n must be a power of two. The default size
777 is set in the kernel config file.
1da177e4
LT
778
779 lp=0 [LP] Specify parallel ports to use, e.g,
780 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
781 lp=reset first parallel port). 'lp=0' disables the
782 lp=auto printer driver. 'lp=reset' (which can be
783 specified in addition to the ports) causes
784 attached printers to be reset. Using
785 lp=port1,port2,... specifies the parallel ports
786 to associate lp devices with, starting with
787 lp0. A port specification may be 'none' to skip
788 that lp device, or a parport name such as
789 'parport0'. Specifying 'lp=auto' instead of a
790 port specification list means that device IDs
791 from each port should be examined, to see if
792 an IEEE 1284-compliant printer is attached; if
793 so, the driver will manage that printer.
794 See also header of drivers/char/lp.c.
795
796 lpj=n [KNL]
797 Sets loops_per_jiffy to given constant, thus avoiding
798 time-consuming boot-time autodetection (up to 250 ms per
799 CPU). 0 enables autodetection (default). To determine
800 the correct value for your kernel, boot with normal
801 autodetection and see what value is printed. Note that
802 on SMP systems the preset will be applied to all CPUs,
803 which is likely to cause problems if your CPUs need
804 significantly divergent settings. An incorrect value
805 will cause delays in the kernel to be wrong, leading to
806 unpredictable I/O errors and other breakage. Although
807 unlikely, in the extreme case this might damage your
808 hardware.
809
810 ltpc= [NET]
811 Format: <io>,<irq>,<dma>
812
a9913044
RD
813 mac5380= [HW,SCSI] Format:
814 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 815
a9913044
RD
816 mac53c9x= [HW,SCSI] Format:
817 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 818
a9913044
RD
819 machvec= [IA64] Force the use of a particular machine-vector
820 (machvec) in a generic kernel.
821 Example: machvec=hpzx1_swiotlb
1da177e4 822
a9913044
RD
823 mad16= [HW,OSS] Format:
824 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
825
826 maui= [HW,OSS]
827 Format: <io>,<irq>
a9913044
RD
828
829 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
830 be mounted
831 Format: <1-256>
832
833 maxcpus= [SMP] Maximum number of processors that an SMP kernel
834 should make use of
835
2b2c3750
BP
836 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
837 equal to this physical address is ignored.
838
a9913044 839 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
840 Should be between 1 and 2^32-1.
841
842 max_report_luns=
a9913044 843 [SCSI] Maximum number of LUNs received.
1da177e4
LT
844 Should be between 1 and 16384.
845
846 mca-pentium [BUGS=IA-32]
847
848 mcatest= [IA-64]
849
850 mcd= [HW,CD]
851 Format: <port>,<irq>,<mitsumi_bug_93_wait>
852
853 mcdx= [HW,CD]
854
855 mce [IA-32] Machine Check Exception
856
857 md= [HW] RAID subsystems devices and level
858 See Documentation/md.txt.
a9913044 859
1da177e4
LT
860 mdacon= [MDA]
861 Format: <first>,<last>
862 Specifies range of consoles to be captured by the MDA.
a9913044 863
1da177e4
LT
864 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
865 Amount of memory to be used when the kernel is not able
866 to see the whole system memory or for test.
867 [IA-32] Use together with memmap= to avoid physical
868 address space collisions. Without memmap= PCI devices
869 could be placed at addresses belonging to unused RAM.
870
871 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
872 memory.
873
69cda7b1 874 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
875 E820 memory map, as specified by the user.
876 Such memmap=exactmap lines can be constructed based on
877 BIOS output or other requirements. See the memmap=nn@ss
878 option description.
879
880 memmap=nn[KMG]@ss[KMG]
881 [KNL] Force usage of a specific region of memory
882 Region of memory to be used, from ss to ss+nn.
883
884 memmap=nn[KMG]#ss[KMG]
885 [KNL,ACPI] Mark specific memory as ACPI data.
886 Region of memory to be used, from ss to ss+nn.
887
888 memmap=nn[KMG]$ss[KMG]
889 [KNL,ACPI] Mark specific memory as reserved.
890 Region of memory to be used, from ss to ss+nn.
891
892 meye.*= [HW] Set MotionEye Camera parameters
893 See Documentation/video4linux/meye.txt.
894
895 mga= [HW,DRM]
896
198e2f18 897 migration_cost=
898 [KNL,SMP] debug: override scheduler migration costs
899 Format: <level-1-usecs>,<level-2-usecs>,...
900 This debugging option can be used to override the
901 default scheduler migration cost matrix. The numbers
902 are indexed by 'CPU domain distance'.
903 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
904 box will set up an intra-core migration cost of
905 1 msec, an inter-core migration cost of 2 msecs,
906 and an inter-node migration cost of 3 msecs.
907
908 WARNING: using the wrong values here can break
909 scheduler performance, so it's only for scheduler
910 development purposes, not production environments.
911
912 migration_debug=
913 [KNL,SMP] migration cost auto-detect verbosity
914 Format=<0|1|2>
915 If a system's migration matrix reported at bootup
916 seems erroneous then this option can be used to
917 increase verbosity of the detection process.
918 We default to 0 (no extra messages), 1 will print
919 some more information, and 2 will be really
920 verbose (probably only useful if you also have a
921 serial console attached to the system).
922
923 migration_factor=
924 [KNL,SMP] multiply/divide migration costs by a factor
925 Format=<percent>
926 This debug option can be used to proportionally
927 increase or decrease the auto-detected migration
928 costs for all entries of the migration matrix.
929 E.g. migration_factor=150 will increase migration
930 costs by 50%. (and thus the scheduler will be less
931 eager migrating cache-hot tasks)
932 migration_factor=80 will decrease migration costs
933 by 20%. (thus the scheduler will be more eager to
934 migrate tasks)
935
936 WARNING: using the wrong values here can break
937 scheduler performance, so it's only for scheduler
938 development purposes, not production environments.
939
1da177e4
LT
940 mousedev.tap_time=
941 [MOUSE] Maximum time between finger touching and
942 leaving touchpad surface for touch to be considered
943 a tap and be reported as a left button click (for
944 touchpads working in absolute mode only).
945 Format: <msecs>
946 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
947 reporting absolute coordinates, such as tablets
948 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
949 reporting absolute coordinates, such as tablets
950
951 mpu401= [HW,OSS]
952 Format: <io>,<irq>
953
954 MTD_Partition= [MTD]
955 Format: <name>,<region-number>,<size>,<offset>
956
a9913044
RD
957 MTD_Region= [MTD] Format:
958 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
959
960 mtdparts= [MTD]
961 See drivers/mtd/cmdline.c.
962
963 mtouchusb.raw_coordinates=
a9913044
RD
964 [HW] Make the MicroTouch USB driver use raw coordinates
965 ('y', default) or cooked coordinates ('n')
1da177e4
LT
966
967 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
968
969 NCR_D700= [HW,SCSI]
970 See header of drivers/scsi/NCR_D700.c.
971
972 ncr5380= [HW,SCSI]
973
974 ncr53c400= [HW,SCSI]
975
976 ncr53c400a= [HW,SCSI]
977
978 ncr53c406a= [HW,SCSI]
979
980 ncr53c8xx= [HW,SCSI]
981
982 netdev= [NET] Network devices parameters
983 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
984 Note that mem_start is often overloaded to mean
985 something different and driver-specific.
a9913044
RD
986 This usage is only documented in each driver source
987 file if at all.
988
1da177e4
LT
989 nfsaddrs= [NFS]
990 See Documentation/nfsroot.txt.
991
992 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
993 See Documentation/nfsroot.txt.
994
a72b4422
TM
995 nfs.callback_tcpport=
996 [NFS] set the TCP port on which the NFSv4 callback
997 channel should listen.
998
58df095b
TM
999 nfs.idmap_cache_timeout=
1000 [NFS] set the maximum lifetime for idmapper cache
1001 entries.
1002
1da177e4
LT
1003 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1004
1005 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1006 emulation library even if a 387 maths coprocessor
1007 is present.
1008
a9913044
RD
1009 noalign [KNL,ARM]
1010
1da177e4
LT
1011 noapic [SMP,APIC] Tells the kernel to not make use of any
1012 IOAPICs that may be present in the system.
1013
1014 noasync [HW,M68K] Disables async and sync negotiation for
1015 all devices.
1016
1017 nobats [PPC] Do not use BATs for mapping kernel lowmem
1018 on "Classic" PPC cores.
1019
1020 nocache [ARM]
a9913044 1021
1da177e4
LT
1022 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1023
1024 noexec [IA-64]
1025
a9913044 1026 noexec [IA-32,X86-64]
1da177e4
LT
1027 noexec=on: enable non-executable mappings (default)
1028 noexec=off: disable nn-executable mappings
1029
4f886511
CE
1030 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1031 register save and restore. The kernel will only save
1032 legacy floating-point registers on task switch.
1da177e4
LT
1033
1034 nohlt [BUGS=ARM]
a9913044 1035
1da177e4
LT
1036 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1037 instruction doesn't work correctly and not to
1038 use it.
1039
1040 nohalt [IA-64] Tells the kernel not to use the power saving
1041 function PAL_HALT_LIGHT when idle. This increases
1042 power-consumption. On the positive side, it reduces
1043 interrupt wake-up latency, which may improve performance
1044 in certain environments such as networked servers or
1045 real-time systems.
1046
1047 noirqdebug [IA-32] Disables the code which attempts to detect and
1048 disable unhandled interrupt sources.
1049
1050 noisapnp [ISAPNP] Disables ISA PnP code.
1051
1052 noinitrd [RAM] Tells the kernel not to load any configured
1053 initial RAM disk.
1054
1055 nointroute [IA-64]
1056
1057 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1058
1059 noltlbs [PPC] Do not use large page/tlb entries for kernel
1060 lowmem mapping on PPC40x.
1061
312f1f01
H
1062 nomca [IA-64] Disable machine check abort handling
1063
abe37e5a
H
1064 nomce [IA-32] Machine Check Exception
1065
1da177e4
LT
1066 noresidual [PPC] Don't use residual data on PReP machines.
1067
a9913044
RD
1068 noresume [SWSUSP] Disables resume and restores original swap
1069 space.
1070
1da177e4
LT
1071 no-scroll [VGA] Disables scrollback.
1072 This is required for the Braillex ib80-piezo Braille
1073 reader made by F.H. Papenmeier (Germany).
1074
1075 nosbagart [IA-64]
1076
4f886511
CE
1077 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1078
1da177e4
LT
1079 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1080
1081 nosync [HW,M68K] Disables sync negotiation for all devices.
1082
1083 notsc [BUGS=IA-32] Disable Time Stamp Counter
1084
1085 nousb [USB] Disable the USB subsystem
1086
1087 nowb [ARM]
a9913044 1088
a61c2d78
DJ
1089 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1090
1da177e4
LT
1091 opl3= [HW,OSS]
1092 Format: <io>
1093
1094 opl3sa= [HW,OSS]
1095 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1096
a9913044
RD
1097 opl3sa2= [HW,OSS] Format:
1098 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1099
1da177e4
LT
1100 oprofile.timer= [HW]
1101 Use timer interrupt instead of performance counters
1102
1103 optcd= [HW,CD]
1104 Format: <io>
1105
1106 osst= [HW,SCSI] SCSI Tape Driver
1107 Format: <buffer_size>,<write_threshold>
1108 See also Documentation/scsi/st.txt.
1109
1110 panic= [KNL] Kernel behaviour on panic
1111 Format: <timeout>
1112
1113 parkbd.port= [HW] Parallel port number the keyboard adapter is
1114 connected to, default is 0.
1115 Format: <parport#>
1116 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1117 0 for XT, 1 for AT (default is AT).
a9913044
RD
1118 Format: <mode>
1119
1120 parport= [HW,PPT] Specify parallel ports. 0 disables.
1121 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1122 Use 'auto' to force the driver to use any
1123 IRQ/DMA settings detected (the default is to
1124 ignore detected IRQ/DMA settings because of
1125 possible conflicts). You can specify the base
1126 address, IRQ, and DMA settings; IRQ and DMA
1127 should be numbers, or 'auto' (for using detected
1128 settings on that particular port), or 'nofifo'
1129 (to avoid using a FIFO even if it is detected).
1130 Parallel ports are assigned in the order they
1131 are specified on the command line, starting
1132 with parport0.
1133
1134 parport_init_mode= [HW,PPT]
1135 Configure VIA parallel port to operate in
1136 a specific mode. This is necessary on Pegasos
1137 computer where firmware has no options for setting
1138 up parallel port mode and sets it to spp.
1139 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1140 Format: [spp|ps2|epp|ecp|ecpepp]
1141
a9913044
RD
1142 pas2= [HW,OSS] Format:
1143 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1144
1da177e4
LT
1145 pas16= [HW,SCSI]
1146 See header of drivers/scsi/pas16.c.
1147
dd287796
AM
1148 pause_on_oops=
1149 Halt all CPUs after the first oops has been printed for
1150 the specified number of seconds. This is to be used if
1151 your oopses keep scrolling off the screen.
1152
1da177e4
LT
1153 pcbit= [HW,ISDN]
1154
1155 pcd. [PARIDE]
1156 See header of drivers/block/paride/pcd.c.
1157 See also Documentation/paride.txt.
1158
a9913044
RD
1159 pci=option[,option...] [PCI] various PCI subsystem options:
1160 off [IA-32] don't probe for the PCI bus
1161 bios [IA-32] force use of PCI BIOS, don't access
1162 the hardware directly. Use this if your machine
1163 has a non-standard PCI host bridge.
1164 nobios [IA-32] disallow use of PCI BIOS, only direct
1165 hardware access methods are allowed. Use this
1166 if you experience crashes upon bootup and you
1167 suspect they are caused by the BIOS.
1168 conf1 [IA-32] Force use of PCI Configuration
1169 Mechanism 1.
1170 conf2 [IA-32] Force use of PCI Configuration
1171 Mechanism 2.
61be6d66
BH
1172 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1173 Configuration
309e57df
MW
1174 nomsi [MSI] If the PCI_MSI kernel config parameter is
1175 enabled, this kernel boot option can be used to
1176 disable the use of MSI interrupts system-wide.
a9913044
RD
1177 nosort [IA-32] Don't sort PCI devices according to
1178 order given by the PCI BIOS. This sorting is
1179 done to get a device order compatible with
1180 older kernels.
1181 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1182 routing table. These calls are known to be buggy
1183 on several machines and they hang the machine
1184 when used, but on other computers it's the only
1185 way to get the interrupt routing table. Try
1186 this option if the kernel is unable to allocate
1187 IRQs or discover secondary PCI buses on your
1188 motherboard.
1189 rom [IA-32] Assign address space to expansion ROMs.
1190 Use with caution as certain devices share
1191 address decoders between ROMs and other
1192 resources.
1193 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1194 assigned automatically to PCI devices. You can
1195 make the kernel exclude IRQs of your ISA cards
1196 this way.
120bb424 1197 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1198 of the PIRQ table (normally generated
1199 by the BIOS) if it is outside the
1200 F0000h-100000h range.
1201 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1202 useful if the kernel is unable to find your
1203 secondary buses and you want to tell it
1204 explicitly which ones they are.
1205 assign-busses [IA-32] Always assign all PCI bus
1206 numbers ourselves, overriding
1207 whatever the firmware may have done.
1208 usepirqmask [IA-32] Honor the possible IRQ mask stored
1209 in the BIOS $PIR table. This is needed on
1210 some systems with broken BIOSes, notably
1211 some HP Pavilion N5400 and Omnibook XE3
1212 notebooks. This will have no effect if ACPI
1213 IRQ routing is enabled.
1214 noacpi [IA-32] Do not use ACPI for IRQ routing
1215 or for PCI scanning.
1216 routeirq Do IRQ routing for all PCI devices.
1217 This is normally done in pci_enable_device(),
1218 so this option is a temporary workaround
1219 for broken drivers that don't call it.
1220 firmware [ARM] Do not re-enumerate the bus but instead
1221 just use the configuration from the
1222 bootloader. This is currently used on
1223 IXP2000 systems where the bus has to be
1224 configured a certain way for adjunct CPUs.
1da177e4
LT
1225
1226 pcmv= [HW,PCMCIA] BadgePAD 4
1227
1228 pd. [PARIDE]
1229 See Documentation/paride.txt.
1230
1231 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1232 boot time.
1233 Format: { 0 | 1 }
1234 See arch/parisc/kernel/pdc_chassis.c
1235
1236 pf. [PARIDE]
1237 See Documentation/paride.txt.
1238
1239 pg. [PARIDE]
1240 See Documentation/paride.txt.
1241
1242 pirq= [SMP,APIC] Manual mp-table setup
1243 See Documentation/i386/IO-APIC.txt.
1244
1245 plip= [PPT,NET] Parallel port network link
1246 Format: { parport<nr> | timid | 0 }
1247 See also Documentation/parport.txt.
1248
1249 pnpacpi= [ACPI]
1250 { off }
1251
1252 pnpbios= [ISAPNP]
1253 { on | off | curr | res | no-curr | no-res }
1254
1255 pnp_reserve_irq=
1256 [ISAPNP] Exclude IRQs for the autoconfiguration
1257
1258 pnp_reserve_dma=
1259 [ISAPNP] Exclude DMAs for the autoconfiguration
1260
1261 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1262 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1263
1264 pnp_reserve_mem=
a9913044
RD
1265 [ISAPNP] Exclude memory regions for the
1266 autoconfiguration.
1da177e4
LT
1267 Ranges are in pairs (memory base and size).
1268
1269 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1270 Format: [schedule,]<number>
1271 Param: "schedule" - profile schedule points.
1272 Param: <number> - step/bucket size as a power of 2 for
1273 statistical time based profiling.
1da177e4 1274
a9913044 1275 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1276 Limit processor to maximum C-state
1277 max_cstate=9 overrides any DMI blacklist limit.
1278
41c0d868
LB
1279 processor.nocst [HW,ACPI]
1280 Ignore the _CST method to determine C-states,
1281 instead using the legacy FADT method
1282
1da177e4
LT
1283 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1284 before loading.
1285 See Documentation/ramdisk.txt.
1286
a9913044
RD
1287 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1288 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1289 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1290 per second.
a9913044
RD
1291 psmouse.resetafter= [HW,MOUSE]
1292 Try to reset the device after so many bad packets
1da177e4
LT
1293 (0 = never).
1294 psmouse.resolution=
1295 [HW,MOUSE] Set desired mouse resolution, in dpi.
1296 psmouse.smartscroll=
a9913044 1297 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1298 0 = disabled, 1 = enabled (default).
1299
1300 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1301 Format:
1302 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1303
1304 pt. [PARIDE]
1305 See Documentation/paride.txt.
1306
1307 quiet= [KNL] Disable log messages
a9913044 1308
1da177e4
LT
1309 r128= [HW,DRM]
1310
1311 raid= [HW,RAID]
1312 See Documentation/md.txt.
1313
1314 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1315 See Documentation/ramdisk.txt.
1316
a9913044 1317 ramdisk_blocksize= [RAM]
1da177e4 1318 See Documentation/ramdisk.txt.
a9913044 1319
1da177e4
LT
1320 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1321 New name for the ramdisk parameter.
1322 See Documentation/ramdisk.txt.
1323
21a1ea9e
DS
1324 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1325 RCU callbacks to process in one batch.
1326
1327 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1328 RCU callbacks over which batch limiting is disabled.
1329
1330 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1331 RCU callbacks below which batch limiting is re-enabled.
1332
1333 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1334 RCU callbacks to queued before forcing reschedule
1335 on all cpus.
1336
ffdfc409
OJ
1337 rdinit= [KNL]
1338 Format: <full_path>
1339 Run specified binary instead of /init from the ramdisk,
1340 used for early userspace startup. See initrd.
1341
1da177e4
LT
1342 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1343 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1344 See arch/*/kernel/reboot.c.
1345
1346 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1347
a9913044
RD
1348 resume= [SWSUSP]
1349 Specify the partition device for software suspend
1da177e4
LT
1350
1351 rhash_entries= [KNL,NET]
1352 Set number of hash buckets for route cache
1353
1354 riscom8= [HW,SERIAL]
1355 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1356
1357 ro [KNL] Mount root device read-only on boot
1358
1359 root= [KNL] Root filesystem
1360
1361 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1362 mount the root filesystem
1363
1364 rootflags= [KNL] Set root filesystem mount option string
1365
1366 rootfstype= [KNL] Set root filesystem type
1367
1368 rw [KNL] Mount root device read-write on boot
1369
1370 S [KNL] Run init in single mode
1371
1372 sa1100ir [NET]
1373 See drivers/net/irda/sa1100_ir.c.
1374
1375 sb= [HW,OSS]
1376 Format: <io>,<irq>,<dma>,<dma2>
1377
1378 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1379
1da177e4
LT
1380 sbpcd= [HW,CD] Soundblaster CD adapter
1381 Format: <io>,<type>
1382 See a comment before function sbpcd_setup() in
1383 drivers/cdrom/sbpcd.c.
1384
1385 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1386 Format: <io>[,<timeout>[,<isapnp>]]
1387
1388 scsi_debug_*= [SCSI]
1389 See drivers/scsi/scsi_debug.c.
1390
1391 scsi_default_dev_flags=
1392 [SCSI] SCSI default device flags
1393 Format: <integer>
1394
1395 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1396 Format: <vendor>:<model>:<flags>
1397 (flags are integer value)
1398
1399 scsi_logging= [SCSI]
1400
1401 selinux [SELINUX] Disable or enable SELinux at boot time.
1402 Format: { "0" | "1" }
1403 See security/selinux/Kconfig help text.
1404 0 -- disable.
1405 1 -- enable.
1406 Default value is set via kernel config option.
1407 If enabled at boot time, /selinux/disable can be used
1408 later to disable prior to initial policy load.
1409
4e5ab4cb
JM
1410 selinux_compat_net =
1411 [SELINUX] Set initial selinux_compat_net flag value.
1412 Format: { "0" | "1" }
1413 0 -- use new secmark-based packet controls
1414 1 -- use legacy packet controls
1415 Default value is 0 (preferred).
1416 Value can be changed at runtime via
1417 /selinux/compat_net.
1418
1da177e4
LT
1419 serialnumber [BUGS=IA-32]
1420
a9913044
RD
1421 sg_def_reserved_size= [SCSI]
1422
1da177e4
LT
1423 sgalaxy= [HW,OSS]
1424 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1425
1426 shapers= [NET]
1427 Maximal number of shapers.
a9913044 1428
1da177e4
LT
1429 sim710= [SCSI,HW]
1430 See header of drivers/scsi/sim710.c.
1431
1432 simeth= [IA-64]
1433 simscsi=
a9913044 1434
1da177e4
LT
1435 sjcd= [HW,CD]
1436 Format: <io>,<irq>,<dma>
1437 See header of drivers/cdrom/sjcd.c.
1438
1439 slram= [HW,MTD]
1440
1441 smart2= [HW]
1442 Format: <io1>[,<io2>[,...,<io8>]]
1443
1444 snd-ad1816a= [HW,ALSA]
1445
1446 snd-ad1848= [HW,ALSA]
1447
1448 snd-ali5451= [HW,ALSA]
1449
1450 snd-als100= [HW,ALSA]
1451
1452 snd-als4000= [HW,ALSA]
1453
1454 snd-azt2320= [HW,ALSA]
1455
1456 snd-cmi8330= [HW,ALSA]
1457
1458 snd-cmipci= [HW,ALSA]
1459
1460 snd-cs4231= [HW,ALSA]
1461
1462 snd-cs4232= [HW,ALSA]
1463
1464 snd-cs4236= [HW,ALSA]
1465
1466 snd-cs4281= [HW,ALSA]
1467
1468 snd-cs46xx= [HW,ALSA]
1469
1470 snd-dt019x= [HW,ALSA]
1471
1472 snd-dummy= [HW,ALSA]
1473
1474 snd-emu10k1= [HW,ALSA]
1475
1476 snd-ens1370= [HW,ALSA]
1477
1478 snd-ens1371= [HW,ALSA]
1479
1480 snd-es968= [HW,ALSA]
1481
1482 snd-es1688= [HW,ALSA]
1483
1484 snd-es18xx= [HW,ALSA]
1485
1486 snd-es1938= [HW,ALSA]
1487
1488 snd-es1968= [HW,ALSA]
1489
1490 snd-fm801= [HW,ALSA]
1491
1492 snd-gusclassic= [HW,ALSA]
1493
1494 snd-gusextreme= [HW,ALSA]
1495
1496 snd-gusmax= [HW,ALSA]
1497
1498 snd-hdsp= [HW,ALSA]
1499
1500 snd-ice1712= [HW,ALSA]
1501
1502 snd-intel8x0= [HW,ALSA]
1503
1504 snd-interwave= [HW,ALSA]
1505
1506 snd-interwave-stb=
1507 [HW,ALSA]
1508
1509 snd-korg1212= [HW,ALSA]
1510
1511 snd-maestro3= [HW,ALSA]
1512
1513 snd-mpu401= [HW,ALSA]
1514
1515 snd-mtpav= [HW,ALSA]
1516
1517 snd-nm256= [HW,ALSA]
1518
1519 snd-opl3sa2= [HW,ALSA]
1520
1521 snd-opti92x-ad1848=
1522 [HW,ALSA]
1523
1524 snd-opti92x-cs4231=
1525 [HW,ALSA]
1526
1527 snd-opti93x= [HW,ALSA]
1528
1529 snd-pmac= [HW,ALSA]
1530
1531 snd-rme32= [HW,ALSA]
1532
1533 snd-rme96= [HW,ALSA]
1534
1535 snd-rme9652= [HW,ALSA]
1536
1537 snd-sb8= [HW,ALSA]
1538
1539 snd-sb16= [HW,ALSA]
1540
1541 snd-sbawe= [HW,ALSA]
1542
1543 snd-serial= [HW,ALSA]
1544
1545 snd-sgalaxy= [HW,ALSA]
1546
1547 snd-sonicvibes= [HW,ALSA]
1548
1549 snd-sun-amd7930=
1550 [HW,ALSA]
1551
1552 snd-sun-cs4231= [HW,ALSA]
1553
1554 snd-trident= [HW,ALSA]
1555
1556 snd-usb-audio= [HW,ALSA,USB]
1557
1558 snd-via82xx= [HW,ALSA]
1559
1560 snd-virmidi= [HW,ALSA]
1561
1562 snd-wavefront= [HW,ALSA]
1563
1564 snd-ymfpci= [HW,ALSA]
a9913044 1565
1da177e4
LT
1566 sonicvibes= [HW,OSS]
1567 Format: <reverb>
a9913044 1568
1da177e4
LT
1569 sonycd535= [HW,CD]
1570 Format: <io>[,<irq>]
1571
1572 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1573 See Documentation/sonypi.txt
1574
1575 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1576 See Documentation/specialix.txt.
1577
1578 spia_io_base= [HW,MTD]
1579 spia_fio_base=
1580 spia_pedr=
1581 spia_peddr=
1582
1583 sscape= [HW,OSS]
1584 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1585
1da177e4
LT
1586 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1587 See Documentation/scsi/st.txt.
1588
1589 st0x= [HW,SCSI]
1590 See header of drivers/scsi/seagate.c.
1591
1592 sti= [PARISC,HW]
1593 Format: <num>
1594 Set the STI (builtin display/keyboard on the HP-PARISC
1595 machines) console (graphic card) which should be used
1596 as the initial boot-console.
1597 See also comment in drivers/video/console/sticore.c.
1598
1599 sti_font= [HW]
1600 See comment in drivers/video/console/sticore.c.
1601
1602 stifb= [HW]
1603 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1604
1da177e4 1605 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1606
1da177e4
LT
1607 switches= [HW,M68k]
1608
1609 sym53c416= [HW,SCSI]
1610 See header of drivers/scsi/sym53c416.c.
1611
1612 t128= [HW,SCSI]
1613 See header of drivers/scsi/t128.c.
1614
1615 tdfx= [HW,DRM]
1616
1617 thash_entries= [KNL,NET]
1618 Set number of hash buckets for TCP connection
1619
1620 time Show timing data prefixed to each printk message line
1621
734efb46 1622 clocksource= [GENERIC_TIME] Override the default clocksource
1623 Override the default clocksource and use the clocksource
1624 with the name specified.
1625
1da177e4
LT
1626 tipar.timeout= [HW,PPT]
1627 Set communications timeout in tenths of a second
1628 (default 15).
1629
1630 tipar.delay= [HW,PPT]
1631 Set inter-bit delay in microseconds (default 10).
1632
1633 tmc8xx= [HW,SCSI]
1634 See header of drivers/scsi/seagate.c.
1635
1636 tmscsim= [HW,SCSI]
1637 See comment before function dc390_setup() in
1638 drivers/scsi/tmscsim.c.
1639
1640 tp720= [HW,PS2]
1641
1642 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1643 Format:
1644 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1645
1da177e4
LT
1646 tsdev.xres= [TS] Horizontal screen resolution.
1647 tsdev.yres= [TS] Vertical screen resolution.
1648
a9913044
RD
1649 turbografx.map[2|3]= [HW,JOY]
1650 TurboGraFX parallel port interface
1651 Format:
1652 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1653 See also Documentation/input/joystick-parport.txt
1654
1655 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1656 See header of drivers/scsi/u14-34f.c.
1657
1658 uart401= [HW,OSS]
1659 Format: <io>,<irq>
1660
1661 uart6850= [HW,OSS]
1662 Format: <io>,<irq>
1663
1da177e4
LT
1664 usbhid.mousepoll=
1665 [USBHID] The interval which mice are to be polled at.
a9913044 1666
1da177e4
LT
1667 video= [FB] Frame buffer configuration
1668 See Documentation/fb/modedb.txt.
1669
1670 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1671 See Documentation/i386/boot.txt and
1672 Documentation/svga.txt.
1da177e4
LT
1673 Use vga=ask for menu.
1674 This is actually a boot loader parameter; the value is
1675 passed to the kernel using a special protocol.
1676
a9913044 1677 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1678 size of <nn>. This can be used to increase the
1679 minimum size (128MB on x86). It can also be used to
1680 decrease the size and leave more room for directly
1681 mapped kernel RAM.
1682
1683 vmhalt= [KNL,S390]
1684
a9913044
RD
1685 vmpoff= [KNL,S390]
1686
1da177e4
LT
1687 waveartist= [HW,OSS]
1688 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1689
1da177e4
LT
1690 wd33c93= [HW,SCSI]
1691 See header of drivers/scsi/wd33c93.c.
1692
1693 wd7000= [HW,SCSI]
1694 See header of drivers/scsi/wd7000.c.
1695
1696 wdt= [WDT] Watchdog
1697 See Documentation/watchdog/watchdog.txt.
1698
1699 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1700 xd_geo= See header of drivers/block/xd.c.
1701
1702 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1703 Format:
1704 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1705
a62eaf15
AK
1706 norandmaps Don't use address space randomization
1707 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1708
1da177e4 1709
a9913044 1710______________________________________________________________________
1da177e4
LT
1711
1712TODO:
1713
1714 Add documentation for ALSA options.
1715 Add more DRM drivers.